Merge branch 'sb/object-store-alloc'
authorJunio C Hamano <gitster@pobox.com>
Mon, 25 Jun 2018 20:22:38 +0000 (13:22 -0700)
committerJunio C Hamano <gitster@pobox.com>
Mon, 25 Jun 2018 20:22:38 +0000 (13:22 -0700)
The conversion to pass "the_repository" and then "a_repository"
throughout the object access API continues.

* sb/object-store-alloc:
alloc: allow arbitrary repositories for alloc functions
object: allow create_object to handle arbitrary repositories
object: allow grow_object_hash to handle arbitrary repositories
alloc: add repository argument to alloc_commit_index
alloc: add repository argument to alloc_report
alloc: add repository argument to alloc_object_node
alloc: add repository argument to alloc_tag_node
alloc: add repository argument to alloc_commit_node
alloc: add repository argument to alloc_tree_node
alloc: add repository argument to alloc_blob_node
object: add repository argument to grow_object_hash
object: add repository argument to create_object
repository: introduce parsed objects field

1  2 
alloc.c
blame.c
cache.h
commit.c
commit.h
merge-recursive.c
object.c
object.h
repository.c
repository.h
tree.c
diff --combined alloc.c
index e8ab14f4a12bc65eb32152192af1faf719e3423c,714df633169df5a2502b27474192c59b24b336a3..c2fc5d68886bf3f74a1f013a3a36c7b5dcad2258
+++ b/alloc.c
@@@ -4,8 -4,7 +4,7 @@@
   * Copyright (C) 2006 Linus Torvalds
   *
   * The standard malloc/free wastes too much space for objects, partly because
-  * it maintains all the allocation infrastructure (which isn't needed, since
-  * we never free an object descriptor anyway), but even more because it ends
+  * it maintains all the allocation infrastructure, but even more because it ends
   * up with maximal alignment because it doesn't know what the object alignment
   * for the new allocation is.
   */
@@@ -15,6 -14,7 +14,7 @@@
  #include "tree.h"
  #include "commit.h"
  #include "tag.h"
+ #include "alloc.h"
  
  #define BLOCKING 1024
  
@@@ -30,8 -30,27 +30,27 @@@ struct alloc_state 
        int count; /* total number of nodes allocated */
        int nr;    /* number of nodes left in current allocation */
        void *p;   /* first free node in current allocation */
+       /* bookkeeping of allocations */
+       void **slabs;
+       int slab_nr, slab_alloc;
  };
  
+ void *allocate_alloc_state(void)
+ {
+       return xcalloc(1, sizeof(struct alloc_state));
+ }
+ void clear_alloc_state(struct alloc_state *s)
+ {
+       while (s->slab_nr > 0) {
+               s->slab_nr--;
+               free(s->slabs[s->slab_nr]);
+       }
+       FREE_AND_NULL(s->slabs);
+ }
  static inline void *alloc_node(struct alloc_state *s, size_t node_size)
  {
        void *ret;
        if (!s->nr) {
                s->nr = BLOCKING;
                s->p = xmalloc(BLOCKING * node_size);
+               ALLOC_GROW(s->slabs, s->slab_nr + 1, s->slab_alloc);
+               s->slabs[s->slab_nr++] = s->p;
        }
        s->nr--;
        s->count++;
        ret = s->p;
        s->p = (char *)s->p + node_size;
        memset(ret, 0, node_size);
        return ret;
  }
  
- static struct alloc_state blob_state;
- void *alloc_blob_node(void)
+ void *alloc_blob_node(struct repository *r)
  {
-       struct blob *b = alloc_node(&blob_state, sizeof(struct blob));
+       struct blob *b = alloc_node(r->parsed_objects->blob_state, sizeof(struct blob));
        b->object.type = OBJ_BLOB;
        return b;
  }
  
- static struct alloc_state tree_state;
- void *alloc_tree_node(void)
+ void *alloc_tree_node(struct repository *r)
  {
-       struct tree *t = alloc_node(&tree_state, sizeof(struct tree));
+       struct tree *t = alloc_node(r->parsed_objects->tree_state, sizeof(struct tree));
        t->object.type = OBJ_TREE;
        return t;
  }
  
- static struct alloc_state tag_state;
- void *alloc_tag_node(void)
+ void *alloc_tag_node(struct repository *r)
  {
-       struct tag *t = alloc_node(&tag_state, sizeof(struct tag));
+       struct tag *t = alloc_node(r->parsed_objects->tag_state, sizeof(struct tag));
        t->object.type = OBJ_TAG;
        return t;
  }
  
- static struct alloc_state object_state;
- void *alloc_object_node(void)
+ void *alloc_object_node(struct repository *r)
  {
-       struct object *obj = alloc_node(&object_state, sizeof(union any_object));
+       struct object *obj = alloc_node(r->parsed_objects->object_state, sizeof(union any_object));
        obj->type = OBJ_NONE;
        return obj;
  }
  
- static struct alloc_state commit_state;
- unsigned int alloc_commit_index(void)
+ unsigned int alloc_commit_index(struct repository *r)
  {
-       static unsigned int count;
-       return count++;
+       return r->parsed_objects->commit_count++;
  }
  
- void *alloc_commit_node(void)
+ void *alloc_commit_node(struct repository *r)
  {
-       struct commit *c = alloc_node(&commit_state, sizeof(struct commit));
+       struct commit *c = alloc_node(r->parsed_objects->commit_state, sizeof(struct commit));
        c->object.type = OBJ_COMMIT;
-       c->index = alloc_commit_index();
+       c->index = alloc_commit_index(r);
 +      c->graph_pos = COMMIT_NOT_FROM_GRAPH;
 +      c->generation = GENERATION_NUMBER_INFINITY;
        return c;
  }
  
@@@ -105,9 -119,10 +121,10 @@@ static void report(const char *name, un
  }
  
  #define REPORT(name, type)    \
-     report(#name, name##_state.count, name##_state.count * sizeof(type) >> 10)
+     report(#name, r->parsed_objects->name##_state->count, \
+                 r->parsed_objects->name##_state->count * sizeof(type) >> 10)
  
- void alloc_report(void)
+ void alloc_report(struct repository *r)
  {
        REPORT(blob, struct blob);
        REPORT(tree, struct tree);
diff --combined blame.c
index ba1b33c7f4e92c432d4cbdcb43b8d061e436f027,3a11f1ce52baebfedbd6ff11633a402eca2b2745..a5c9bd78ab09ce1d1ce40f82ccf13fcc8d973eec
+++ b/blame.c
@@@ -6,24 -6,7 +6,25 @@@
  #include "diffcore.h"
  #include "tag.h"
  #include "blame.h"
+ #include "alloc.h"
 +#include "commit-slab.h"
 +
 +define_commit_slab(blame_suspects, struct blame_origin *);
 +static struct blame_suspects blame_suspects;
 +
 +struct blame_origin *get_blame_suspects(struct commit *commit)
 +{
 +      struct blame_origin **result;
 +
 +      result = blame_suspects_peek(&blame_suspects, commit);
 +
 +      return result ? *result : NULL;
 +}
 +
 +static void set_blame_suspects(struct commit *commit, struct blame_origin *origin)
 +{
 +      *blame_suspects_at(&blame_suspects, commit) = origin;
 +}
  
  void blame_origin_decref(struct blame_origin *o)
  {
                        blame_origin_decref(o->previous);
                free(o->file.ptr);
                /* Should be present exactly once in commit chain */
 -              for (p = o->commit->util; p; l = p, p = p->next) {
 +              for (p = get_blame_suspects(o->commit); p; l = p, p = p->next) {
                        if (p == o) {
                                if (l)
                                        l->next = p->next;
                                else
 -                                      o->commit->util = p->next;
 +                                      set_blame_suspects(o->commit, p->next);
                                free(o);
                                return;
                        }
@@@ -59,8 -42,8 +60,8 @@@ static struct blame_origin *make_origin
        FLEX_ALLOC_STR(o, path, path);
        o->commit = commit;
        o->refcnt = 1;
 -      o->next = commit->util;
 -      commit->util = o;
 +      o->next = get_blame_suspects(commit);
 +      set_blame_suspects(commit, o);
        return o;
  }
  
@@@ -72,13 -55,13 +73,13 @@@ static struct blame_origin *get_origin(
  {
        struct blame_origin *o, *l;
  
 -      for (o = commit->util, l = NULL; o; l = o, o = o->next) {
 +      for (o = get_blame_suspects(commit), l = NULL; o; l = o, o = o->next) {
                if (!strcmp(o->path, path)) {
                        /* bump to front */
                        if (l) {
                                l->next = o->next;
 -                              o->next = commit->util;
 -                              commit->util = o;
 +                              o->next = get_blame_suspects(commit);
 +                              set_blame_suspects(commit, o);
                        }
                        return blame_origin_incref(o);
                }
@@@ -179,7 -162,7 +180,7 @@@ static struct commit *fake_working_tree
  
        read_cache();
        time(&now);
-       commit = alloc_commit_node();
+       commit = alloc_commit_node(the_repository);
        commit->object.parsed = 1;
        commit->date = now;
        parent_tail = &commit->parents;
@@@ -496,7 -479,7 +497,7 @@@ static void queue_blames(struct blame_s
                porigin->suspects = blame_merge(porigin->suspects, sorted);
        else {
                struct blame_origin *o;
 -              for (o = porigin->commit->util; o; o = o->next) {
 +              for (o = get_blame_suspects(porigin->commit); o; o = o->next) {
                        if (o->suspects) {
                                porigin->suspects = sorted;
                                return;
@@@ -543,7 -526,7 +544,7 @@@ static struct blame_origin *find_origin
        const char *paths[2];
  
        /* First check any existing origins */
 -      for (porigin = parent->util; porigin; porigin = porigin->next)
 +      for (porigin = get_blame_suspects(parent); porigin; porigin = porigin->next)
                if (!strcmp(porigin->path, origin->path)) {
                        /*
                         * The same path between origin and its parent
        diff_setup_done(&diff_opts);
  
        if (is_null_oid(&origin->commit->object.oid))
 -              do_diff_cache(&parent->tree->object.oid, &diff_opts);
 +              do_diff_cache(get_commit_tree_oid(parent), &diff_opts);
        else
 -              diff_tree_oid(&parent->tree->object.oid,
 -                            &origin->commit->tree->object.oid,
 +              diff_tree_oid(get_commit_tree_oid(parent),
 +                            get_commit_tree_oid(origin->commit),
                              "", &diff_opts);
        diffcore_std(&diff_opts);
  
@@@ -638,10 -621,10 +639,10 @@@ static struct blame_origin *find_rename
        diff_setup_done(&diff_opts);
  
        if (is_null_oid(&origin->commit->object.oid))
 -              do_diff_cache(&parent->tree->object.oid, &diff_opts);
 +              do_diff_cache(get_commit_tree_oid(parent), &diff_opts);
        else
 -              diff_tree_oid(&parent->tree->object.oid,
 -                            &origin->commit->tree->object.oid,
 +              diff_tree_oid(get_commit_tree_oid(parent),
 +                            get_commit_tree_oid(origin->commit),
                              "", &diff_opts);
        diffcore_std(&diff_opts);
  
@@@ -1273,10 -1256,10 +1274,10 @@@ static void find_copy_in_parent(struct 
                diff_opts.flags.find_copies_harder = 1;
  
        if (is_null_oid(&target->commit->object.oid))
 -              do_diff_cache(&parent->tree->object.oid, &diff_opts);
 +              do_diff_cache(get_commit_tree_oid(parent), &diff_opts);
        else
 -              diff_tree_oid(&parent->tree->object.oid,
 -                            &target->commit->tree->object.oid,
 +              diff_tree_oid(get_commit_tree_oid(parent),
 +                            get_commit_tree_oid(target->commit),
                              "", &diff_opts);
  
        if (!diff_opts.flags.find_copies_harder)
@@@ -1568,7 -1551,7 +1569,7 @@@ void assign_blame(struct blame_scoreboa
  
        while (commit) {
                struct blame_entry *ent;
 -              struct blame_origin *suspect = commit->util;
 +              struct blame_origin *suspect = get_blame_suspects(commit);
  
                /* find one suspect to break down */
                while (suspect && !suspect->suspects)
@@@ -1770,8 -1753,6 +1771,8 @@@ void setup_scoreboard(struct blame_scor
        struct commit *final_commit = NULL;
        enum object_type type;
  
 +      init_blame_suspects(&blame_suspects);
 +
        if (sb->reverse && sb->contents_from)
                die(_("--contents and --reverse do not blend well."));
  
                        l->item = c;
                        if (add_decoration(&sb->revs->children,
                                           &c->parents->item->object, l))
 -                              die("BUG: not unique item in first-parent chain");
 +                              BUG("not unique item in first-parent chain");
                        c = c->parents->item;
                }
  
        }
  
        if (is_null_oid(&sb->final->object.oid)) {
 -              o = sb->final->util;
 +              o = get_blame_suspects(sb->final);
                sb->final_buf = xmemdupz(o->file.ptr, o->file.size);
                sb->final_buf_size = o->file.size;
        }
diff --combined cache.h
index 89a107a7f79175c600eb2a9689982912541ae4e7,c75559b7d38a2230078754db212ab0e04abc487d..d49092d94d1970cc7e07ade8064793fa64d8f362
+++ b/cache.h
@@@ -324,7 -324,7 +324,7 @@@ struct index_state 
                 drop_cache_tree : 1;
        struct hashmap name_hash;
        struct hashmap dir_hash;
 -      unsigned char sha1[20];
 +      struct object_id oid;
        struct untracked_cache *untracked;
        uint64_t fsmonitor_last_update;
        struct ewah_bitmap *fsmonitor_dirty;
@@@ -373,13 -373,6 +373,13 @@@ extern void free_name_hash(struct index
  #define read_blob_data_from_cache(path, sz) read_blob_data_from_index(&the_index, (path), (sz))
  #endif
  
 +#define TYPE_BITS 3
 +
 +/*
 + * Values in this enum (except those outside the 3 bit range) are part
 + * of pack file format. See Documentation/technical/pack-format.txt
 + * for more information.
 + */
  enum object_type {
        OBJ_BAD = -1,
        OBJ_NONE = 0,
@@@ -435,7 -428,6 +435,7 @@@ static inline enum object_type object_t
  #define GIT_ICASE_PATHSPECS_ENVIRONMENT "GIT_ICASE_PATHSPECS"
  #define GIT_QUARANTINE_ENVIRONMENT "GIT_QUARANTINE_PATH"
  #define GIT_OPTIONAL_LOCKS_ENVIRONMENT "GIT_OPTIONAL_LOCKS"
 +#define GIT_TEXT_DOMAIN_DIR_ENVIRONMENT "GIT_TEXTDOMAINDIR"
  
  /*
   * Environment variable used in handshaking the wire protocol.
@@@ -485,7 -477,7 +485,7 @@@ extern const char *get_git_common_dir(v
  extern char *get_object_directory(void);
  extern char *get_index_file(void);
  extern char *get_graft_file(void);
 -extern int set_git_dir(const char *path);
 +extern void set_git_dir(const char *path);
  extern int get_common_dir_noenv(struct strbuf *sb, const char *gitdir);
  extern int get_common_dir(struct strbuf *sb, const char *gitdir);
  extern const char *get_git_namespace(void);
@@@ -642,7 -634,7 +642,7 @@@ extern int unmerged_index(const struct 
   */
  extern int index_has_changes(struct strbuf *sb);
  
 -extern int verify_path(const char *path);
 +extern int verify_path(const char *path, unsigned mode);
  extern int strcmp_offset(const char *s1, const char *s2, size_t *first_change);
  extern int index_dir_exists(struct index_state *istate, const char *name, int namelen);
  extern void adjust_dirname_case(struct index_state *istate, char *name);
@@@ -813,7 -805,6 +813,7 @@@ extern char *git_replace_ref_base
  
  extern int fsync_object_files;
  extern int core_preload_index;
 +extern int core_commit_graph;
  extern int core_apply_sparse_checkout;
  extern int precomposed_unicode;
  extern int protect_hfs;
@@@ -1017,10 -1008,21 +1017,10 @@@ static inline void oidclr(struct object
        memset(oid->hash, 0, GIT_MAX_RAWSZ);
  }
  
 -
 -#define EMPTY_TREE_SHA1_HEX \
 -      "4b825dc642cb6eb9a060e54bf8d69288fbee4904"
 -#define EMPTY_TREE_SHA1_BIN_LITERAL \
 -       "\x4b\x82\x5d\xc6\x42\xcb\x6e\xb9\xa0\x60" \
 -       "\xe5\x4b\xf8\xd6\x92\x88\xfb\xee\x49\x04"
 -extern const struct object_id empty_tree_oid;
 -#define EMPTY_TREE_SHA1_BIN (empty_tree_oid.hash)
 -
 -#define EMPTY_BLOB_SHA1_HEX \
 -      "e69de29bb2d1d6434b8b29ae775ad8c2e48c5391"
 -#define EMPTY_BLOB_SHA1_BIN_LITERAL \
 -      "\xe6\x9d\xe2\x9b\xb2\xd1\xd6\x43\x4b\x8b" \
 -      "\x29\xae\x77\x5a\xd8\xc2\xe4\x8c\x53\x91"
 -extern const struct object_id empty_blob_oid;
 +static inline void oidread(struct object_id *oid, const unsigned char *hash)
 +{
 +      memcpy(oid->hash, hash, the_hash_algo->rawsz);
 +}
  
  static inline int is_empty_blob_sha1(const unsigned char *sha1)
  {
@@@ -1042,9 -1044,6 +1042,9 @@@ static inline int is_empty_tree_oid(con
        return !oidcmp(oid, the_hash_algo->empty_tree);
  }
  
 +const char *empty_tree_oid_hex(void);
 +const char *empty_blob_oid_hex(void);
 +
  /* set default permissions by passing mode arguments to open(2) */
  int git_mkstemps_mode(char *pattern, int suffix_len, int mode);
  int git_mkstemp_mode(char *pattern, int mode);
@@@ -1160,15 -1159,7 +1160,15 @@@ int normalize_path_copy(char *dst, cons
  int longest_ancestor_length(const char *path, struct string_list *prefixes);
  char *strip_path_suffix(const char *path, const char *suffix);
  int daemon_avoid_alias(const char *path);
 -extern int is_ntfs_dotgit(const char *name);
 +
 +/*
 + * These functions match their is_hfs_dotgit() counterparts; see utf8.h for
 + * details.
 + */
 +int is_ntfs_dotgit(const char *name);
 +int is_ntfs_dotgitmodules(const char *name);
 +int is_ntfs_dotgitignore(const char *name);
 +int is_ntfs_dotgitattributes(const char *name);
  
  /*
   * Returns true iff "str" could be confused as a command-line option when
@@@ -1260,7 -1251,7 +1260,7 @@@ extern int has_object_file_with_flags(c
   * with the specified name.  This function does not respect replace
   * references.
   */
 -extern int has_loose_object_nonlocal(const unsigned char *sha1);
 +extern int has_loose_object_nonlocal(const struct object_id *oid);
  
  extern void assert_oid_type(const struct object_id *oid, enum object_type expect);
  
@@@ -1291,6 -1282,7 +1291,6 @@@ static inline int hex2chr(const char *s
  #define FALLBACK_DEFAULT_ABBREV 7
  
  struct object_context {
 -      unsigned char tree[20];
        unsigned mode;
        /*
         * symlink_path is only used by get_tree_entry_follow_symlinks,
@@@ -1557,6 -1549,7 +1557,6 @@@ struct pack_window 
  
  struct pack_entry {
        off_t offset;
 -      unsigned char sha1[20];
        struct packed_git *p;
  };
  
@@@ -1770,15 -1763,6 +1770,6 @@@ extern const char *excludes_file
  int decode_85(char *dst, const char *line, int linelen);
  void encode_85(char *buf, const unsigned char *data, int bytes);
  
- /* alloc.c */
- extern void *alloc_blob_node(void);
- extern void *alloc_tree_node(void);
- extern void *alloc_commit_node(void);
- extern void *alloc_tag_node(void);
- extern void *alloc_object_node(void);
- extern void alloc_report(void);
- extern unsigned int alloc_commit_index(void);
  /* pkt-line.c */
  void packet_trace_identity(const char *prog);
  
@@@ -1826,6 -1810,11 +1817,6 @@@ extern int ws_blank_line(const char *li
  void overlay_tree_on_index(struct index_state *istate,
                           const char *tree_name, const char *prefix);
  
 -char *alias_lookup(const char *alias);
 -int split_cmdline(char *cmdline, const char ***argv);
 -/* Takes a negative value returned by split_cmdline */
 -const char *split_cmdline_strerror(int cmdline_errno);
 -
  /* setup.c */
  struct startup_info {
        int have_repository;
diff --combined commit.c
index 298ad747c6e0d8b1e800b5e643ab0fa6f67cd491,5eb4d2f08f8d093e871072035b0ad8024e583cba..0c3b75aeffea75956adf2190e763b0d753c848c5
+++ b/commit.c
@@@ -1,19 -1,18 +1,20 @@@
  #include "cache.h"
  #include "tag.h"
  #include "commit.h"
 +#include "commit-graph.h"
  #include "pkt-line.h"
  #include "utf8.h"
  #include "diff.h"
  #include "revision.h"
  #include "notes.h"
+ #include "alloc.h"
  #include "gpg-interface.h"
  #include "mergesort.h"
  #include "commit-slab.h"
  #include "prio-queue.h"
  #include "sha1-lookup.h"
  #include "wt-status.h"
 +#include "advice.h"
  
  static struct commit_extra_header *read_commit_extra_header_lines(const char *buf, size_t len, const char **);
  
@@@ -52,7 -51,8 +53,8 @@@ struct commit *lookup_commit(const stru
  {
        struct object *obj = lookup_object(oid->hash);
        if (!obj)
-               return create_object(oid->hash, alloc_commit_node());
+               return create_object(the_repository, oid->hash,
+                                    alloc_commit_node(the_repository));
        return object_as_type(obj, OBJ_COMMIT, 0);
  }
  
@@@ -178,15 -178,6 +180,15 @@@ static int read_graft_file(const char *
        struct strbuf buf = STRBUF_INIT;
        if (!fp)
                return -1;
 +      if (advice_graft_file_deprecated)
 +              advise(_("Support for <GIT_DIR>/info/grafts is deprecated\n"
 +                       "and will be removed in a future Git version.\n"
 +                       "\n"
 +                       "Please use \"git replace --convert-graft-file\"\n"
 +                       "to convert the grafts into replace refs.\n"
 +                       "\n"
 +                       "Turn this message off by running\n"
 +                       "\"git config advice.graftFileDeprecated false\""));
        while (!strbuf_getwholeline(&buf, fp, '\n')) {
                /* The format is just "Commit Parent1 Parent2 ...\n" */
                struct commit_graft *graft = read_graft_line(&buf);
@@@ -207,9 -198,6 +209,9 @@@ static void prepare_commit_graft(void
  
        if (commit_graft_prepared)
                return;
 +      if (!startup_info->have_repository)
 +              return;
 +
        graft_file = get_graft_file();
        read_graft_file(graft_file);
        /* make sure shallows are read */
@@@ -309,22 -297,17 +311,33 @@@ void free_commit_buffer(struct commit *
        }
  }
  
 -      c->tree = NULL;
 +struct tree *get_commit_tree(const struct commit *commit)
 +{
 +      if (commit->maybe_tree || !commit->object.parsed)
 +              return commit->maybe_tree;
 +
 +      if (commit->graph_pos == COMMIT_NOT_FROM_GRAPH)
 +              BUG("commit has NULL tree, but was not loaded from commit-graph");
 +
 +      return get_commit_tree_in_graph(commit);
 +}
 +
 +struct object_id *get_commit_tree_oid(const struct commit *commit)
 +{
 +      return &get_commit_tree(commit)->object.oid;
 +}
 +
+ void release_commit_memory(struct commit *c)
+ {
++      c->maybe_tree = NULL;
+       c->index = 0;
+       free_commit_buffer(c);
+       free_commit_list(c->parents);
+       /* TODO: what about commit->util? */
+       c->object.parsed = 0;
+ }
  const void *detach_commit_buffer(struct commit *commit, unsigned long *sizep)
  {
        struct commit_buffer *v = buffer_slab_peek(&buffer_slab, commit);
        return ret;
  }
  
 -int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size)
 +int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size, int check_graph)
  {
        const char *tail = buffer;
        const char *bufptr = buffer;
        if (tail <= bufptr + tree_entry_len + 1 || memcmp(bufptr, "tree ", 5) ||
                        bufptr[tree_entry_len] != '\n')
                return error("bogus commit object %s", oid_to_hex(&item->object.oid));
 -      if (get_sha1_hex(bufptr + 5, parent.hash) < 0)
 +      if (get_oid_hex(bufptr + 5, &parent) < 0)
                return error("bad tree pointer in commit %s",
                             oid_to_hex(&item->object.oid));
 -      item->tree = lookup_tree(&parent);
 +      item->maybe_tree = lookup_tree(&parent);
        bufptr += tree_entry_len + 1; /* "tree " + "hex sha1" + "\n" */
        pptr = &item->parents;
  
                struct commit *new_parent;
  
                if (tail <= bufptr + parent_entry_len + 1 ||
 -                  get_sha1_hex(bufptr + 7, parent.hash) ||
 +                  get_oid_hex(bufptr + 7, &parent) ||
                    bufptr[parent_entry_len] != '\n')
                        return error("bad parents in commit %s", oid_to_hex(&item->object.oid));
                bufptr += parent_entry_len + 1;
        }
        item->date = parse_commit_date(bufptr, tail);
  
 +      if (check_graph)
 +              load_commit_graph_info(item);
 +
        return 0;
  }
  
@@@ -416,8 -396,6 +429,8 @@@ int parse_commit_gently(struct commit *
                return -1;
        if (item->object.parsed)
                return 0;
 +      if (parse_commit_in_graph(item))
 +              return 0;
        buffer = read_object_file(&item->object.oid, &type, &size);
        if (!buffer)
                return quiet_on_missing ? -1 :
                return error("Object %s not a commit",
                             oid_to_hex(&item->object.oid));
        }
 -      ret = parse_commit_buffer(item, buffer, size);
 +      ret = parse_commit_buffer(item, buffer, size, 0);
        if (save_commit_buffer && !ret) {
                set_commit_buffer(item, buffer, size);
                return 0;
@@@ -656,24 -634,6 +669,24 @@@ static int compare_commits_by_author_da
        return 0;
  }
  
 +int compare_commits_by_gen_then_commit_date(const void *a_, const void *b_, void *unused)
 +{
 +      const struct commit *a = a_, *b = b_;
 +
 +      /* newer commits first */
 +      if (a->generation < b->generation)
 +              return 1;
 +      else if (a->generation > b->generation)
 +              return -1;
 +
 +      /* use date as a heuristic when generations are equal */
 +      if (a->date < b->date)
 +              return 1;
 +      else if (a->date > b->date)
 +              return -1;
 +      return 0;
 +}
 +
  int compare_commits_by_commit_date(const void *a_, const void *b_, void *unused)
  {
        const struct commit *a = a_, *b = b_;
@@@ -821,14 -781,11 +834,14 @@@ static int queue_has_nonstale(struct pr
  }
  
  /* all input commits in one and twos[] must have been parsed! */
 -static struct commit_list *paint_down_to_common(struct commit *one, int n, struct commit **twos)
 +static struct commit_list *paint_down_to_common(struct commit *one, int n,
 +                                              struct commit **twos,
 +                                              int min_generation)
  {
 -      struct prio_queue queue = { compare_commits_by_commit_date };
 +      struct prio_queue queue = { compare_commits_by_gen_then_commit_date };
        struct commit_list *result = NULL;
        int i;
 +      uint32_t last_gen = GENERATION_NUMBER_INFINITY;
  
        one->object.flags |= PARENT1;
        if (!n) {
                struct commit_list *parents;
                int flags;
  
 +              if (commit->generation > last_gen)
 +                      BUG("bad generation skip %8x > %8x at %s",
 +                          commit->generation, last_gen,
 +                          oid_to_hex(&commit->object.oid));
 +              last_gen = commit->generation;
 +
 +              if (commit->generation < min_generation)
 +                      break;
 +
                flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
                if (flags == (PARENT1 | PARENT2)) {
                        if (!(commit->object.flags & RESULT)) {
@@@ -904,7 -852,7 +917,7 @@@ static struct commit_list *merge_bases_
                        return NULL;
        }
  
 -      list = paint_down_to_common(one, n, twos);
 +      list = paint_down_to_common(one, n, twos, 0);
  
        while (list) {
                struct commit *commit = pop_commit(&list);
@@@ -962,7 -910,6 +975,7 @@@ static int remove_redundant(struct comm
                parse_commit(array[i]);
        for (i = 0; i < cnt; i++) {
                struct commit_list *common;
 +              uint32_t min_generation = array[i]->generation;
  
                if (redundant[i])
                        continue;
                                continue;
                        filled_index[filled] = j;
                        work[filled++] = array[j];
 +
 +                      if (array[j]->generation < min_generation)
 +                              min_generation = array[j]->generation;
                }
 -              common = paint_down_to_common(array[i], filled, work);
 +              common = paint_down_to_common(array[i], filled, work,
 +                                            min_generation);
                if (array[i]->object.flags & PARENT2)
                        redundant[i] = 1;
                for (j = 0; j < filled; j++)
@@@ -1086,21 -1029,14 +1099,21 @@@ int in_merge_bases_many(struct commit *
  {
        struct commit_list *bases;
        int ret = 0, i;
 +      uint32_t min_generation = GENERATION_NUMBER_INFINITY;
  
        if (parse_commit(commit))
                return ret;
 -      for (i = 0; i < nr_reference; i++)
 +      for (i = 0; i < nr_reference; i++) {
                if (parse_commit(reference[i]))
                        return ret;
 +              if (reference[i]->generation < min_generation)
 +                      min_generation = reference[i]->generation;
 +      }
 +
 +      if (commit->generation > min_generation)
 +              return ret;
  
 -      bases = paint_down_to_common(commit, nr_reference, reference);
 +      bases = paint_down_to_common(commit, nr_reference, reference, commit->generation);
        if (commit->object.flags & PARENT2)
                ret = 1;
        clear_commit_marks(commit, all_flags);
@@@ -1365,19 -1301,17 +1378,19 @@@ struct commit_extra_header *read_commit
        return extra;
  }
  
 -void for_each_mergetag(each_mergetag_fn fn, struct commit *commit, void *data)
 +int for_each_mergetag(each_mergetag_fn fn, struct commit *commit, void *data)
  {
        struct commit_extra_header *extra, *to_free;
 +      int res = 0;
  
        to_free = read_commit_extra_headers(commit, NULL);
 -      for (extra = to_free; extra; extra = extra->next) {
 +      for (extra = to_free; !res && extra; extra = extra->next) {
                if (strcmp(extra->key, "mergetag"))
                        continue; /* not a merge tag */
 -              fn(commit, extra, data);
 +              res = fn(commit, extra, data);
        }
        free_commit_extra_headers(to_free);
 +      return res;
  }
  
  static inline int standard_header_field(const char *field, size_t len)
        return result;
  }
  
 +define_commit_slab(merge_desc_slab, struct merge_remote_desc *);
 +static struct merge_desc_slab merge_desc_slab = COMMIT_SLAB_INIT(1, merge_desc_slab);
 +
 +struct merge_remote_desc *merge_remote_util(struct commit *commit)
 +{
 +      return *merge_desc_slab_at(&merge_desc_slab, commit);
 +}
 +
  void set_merge_remote_desc(struct commit *commit,
                           const char *name, struct object *obj)
  {
        struct merge_remote_desc *desc;
        FLEX_ALLOC_STR(desc, name, name);
        desc->obj = obj;
 -      commit->util = desc;
 +      *merge_desc_slab_at(&merge_desc_slab, commit) = desc;
  }
  
  struct commit *get_merge_parent(const char *name)
                return NULL;
        obj = parse_object(&oid);
        commit = (struct commit *)peel_to_type(name, 0, obj, OBJ_COMMIT);
 -      if (commit && !commit->util)
 +      if (commit && !merge_remote_util(commit))
                set_merge_remote_desc(commit, name, obj);
        return commit;
  }
diff --combined commit.h
index cb943013d06a58f2e0427a33f5ab718df23e730f,2d764ab7d8e63536e06a83d78a13952fc8b7ebbe..3ad07c2e3d092a97e3bc20091566f4b967b6bc8c
+++ b/commit.h
@@@ -9,35 -9,18 +9,35 @@@
  #include "string-list.h"
  #include "pretty.h"
  
 +#define COMMIT_NOT_FROM_GRAPH 0xFFFFFFFF
 +#define GENERATION_NUMBER_INFINITY 0xFFFFFFFF
 +#define GENERATION_NUMBER_MAX 0x3FFFFFFF
 +#define GENERATION_NUMBER_ZERO 0
 +
  struct commit_list {
        struct commit *item;
        struct commit_list *next;
  };
  
 +/*
 + * The size of this struct matters in full repo walk operations like
 + * 'git clone' or 'git gc'. Consider using commit-slab to attach data
 + * to a commit instead of adding new fields here.
 + */
  struct commit {
        struct object object;
 -      void *util;
 -      unsigned int index;
        timestamp_t date;
        struct commit_list *parents;
 -      struct tree *tree;
 +
 +      /*
 +       * If the commit is loaded from the commit-graph file, then this
 +       * member may be NULL. Only access it through get_commit_tree()
 +       * or get_commit_tree_oid().
 +       */
 +      struct tree *maybe_tree;
 +      uint32_t graph_pos;
 +      uint32_t generation;
 +      unsigned int index;
  };
  
  extern int save_commit_buffer;
@@@ -76,7 -59,7 +76,7 @@@ struct commit *lookup_commit_reference_
   */
  struct commit *lookup_commit_or_die(const struct object_id *oid, const char *ref_name);
  
 -int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size);
 +int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size, int check_graph);
  int parse_commit_gently(struct commit *item, int quiet_on_missing);
  static inline int parse_commit(struct commit *item)
  {
@@@ -116,9 -99,12 +116,15 @@@ void unuse_commit_buffer(const struct c
   */
  void free_commit_buffer(struct commit *);
  
 +struct tree *get_commit_tree(const struct commit *);
 +struct object_id *get_commit_tree_oid(const struct commit *);
 +
+ /*
+  * Release memory related to a commit, including the parent list and
+  * any cached object buffer.
+  */
+ void release_commit_memory(struct commit *c);
  /*
   * Disassociate any cached object buffer from the commit, but do not free it.
   * The buffer (or NULL, if none) is returned.
@@@ -311,16 -297,16 +317,16 @@@ extern const char *find_commit_header(c
  /* Find the end of the log message, the right place for a new trailer. */
  extern int ignore_non_trailer(const char *buf, size_t len);
  
 -typedef void (*each_mergetag_fn)(struct commit *commit, struct commit_extra_header *extra,
 +typedef int (*each_mergetag_fn)(struct commit *commit, struct commit_extra_header *extra,
                                 void *cb_data);
  
 -extern void for_each_mergetag(each_mergetag_fn fn, struct commit *commit, void *data);
 +extern int for_each_mergetag(each_mergetag_fn fn, struct commit *commit, void *data);
  
  struct merge_remote_desc {
        struct object *obj; /* the named object, could be a tag */
        char name[FLEX_ARRAY];
  };
 -#define merge_remote_util(commit) ((struct merge_remote_desc *)((commit)->util))
 +extern struct merge_remote_desc *merge_remote_util(struct commit *);
  extern void set_merge_remote_desc(struct commit *commit,
                                  const char *name, struct object *obj);
  
@@@ -345,7 -331,6 +351,7 @@@ extern int remove_signature(struct strb
  extern int check_commit_signature(const struct commit *commit, struct signature_check *sigc);
  
  int compare_commits_by_commit_date(const void *a_, const void *b_, void *unused);
 +int compare_commits_by_gen_then_commit_date(const void *a_, const void *b_, void *unused);
  
  LAST_ARG_MUST_BE_NULL
  extern int run_commit_hook(int editor_is_used, const char *index_file, const char *name, ...);
diff --combined merge-recursive.c
index 404f050cafe919023ec86d14230a0f6455714538,cbded673c282fd888f239202878ad452e18a3cdf..bed4a5be02404ef512ba5cfcd9bb33ac04a4ca47
@@@ -15,6 -15,7 +15,7 @@@
  #include "diff.h"
  #include "diffcore.h"
  #include "tag.h"
+ #include "alloc.h"
  #include "unpack-trees.h"
  #include "string-list.h"
  #include "xdiff-interface.h"
@@@ -23,7 -24,6 +24,7 @@@
  #include "merge-recursive.h"
  #include "dir.h"
  #include "submodule.h"
 +#include "revision.h"
  
  struct path_hashmap_entry {
        struct hashmap_entry e;
@@@ -50,67 -50,6 +51,67 @@@ static unsigned int path_hash(const cha
        return ignore_case ? strihash(path) : strhash(path);
  }
  
 +static struct dir_rename_entry *dir_rename_find_entry(struct hashmap *hashmap,
 +                                                    char *dir)
 +{
 +      struct dir_rename_entry key;
 +
 +      if (dir == NULL)
 +              return NULL;
 +      hashmap_entry_init(&key, strhash(dir));
 +      key.dir = dir;
 +      return hashmap_get(hashmap, &key, NULL);
 +}
 +
 +static int dir_rename_cmp(const void *unused_cmp_data,
 +                        const void *entry,
 +                        const void *entry_or_key,
 +                        const void *unused_keydata)
 +{
 +      const struct dir_rename_entry *e1 = entry;
 +      const struct dir_rename_entry *e2 = entry_or_key;
 +
 +      return strcmp(e1->dir, e2->dir);
 +}
 +
 +static void dir_rename_init(struct hashmap *map)
 +{
 +      hashmap_init(map, dir_rename_cmp, NULL, 0);
 +}
 +
 +static void dir_rename_entry_init(struct dir_rename_entry *entry,
 +                                char *directory)
 +{
 +      hashmap_entry_init(entry, strhash(directory));
 +      entry->dir = directory;
 +      entry->non_unique_new_dir = 0;
 +      strbuf_init(&entry->new_dir, 0);
 +      string_list_init(&entry->possible_new_dirs, 0);
 +}
 +
 +static struct collision_entry *collision_find_entry(struct hashmap *hashmap,
 +                                                  char *target_file)
 +{
 +      struct collision_entry key;
 +
 +      hashmap_entry_init(&key, strhash(target_file));
 +      key.target_file = target_file;
 +      return hashmap_get(hashmap, &key, NULL);
 +}
 +
 +static int collision_cmp(void *unused_cmp_data,
 +                       const struct collision_entry *e1,
 +                       const struct collision_entry *e2,
 +                       const void *unused_keydata)
 +{
 +      return strcmp(e1->target_file, e2->target_file);
 +}
 +
 +static void collision_init(struct hashmap *map)
 +{
 +      hashmap_init(map, (hashmap_cmp_fn) collision_cmp, NULL, 0);
 +}
 +
  static void flush_output(struct merge_options *o)
  {
        if (o->buffer_output < 2 && o->obuf.len) {
@@@ -160,10 -99,10 +161,10 @@@ static struct tree *shift_tree_object(s
  
  static struct commit *make_virtual_commit(struct tree *tree, const char *comment)
  {
-       struct commit *commit = alloc_commit_node();
+       struct commit *commit = alloc_commit_node(the_repository);
  
        set_merge_remote_desc(commit, comment, (struct object *)commit);
 -      commit->tree = tree;
 +      commit->maybe_tree = tree;
        commit->object.parsed = 1;
        return commit;
  }
@@@ -181,7 -120,6 +182,7 @@@ static int oid_eq(const struct object_i
  
  enum rename_type {
        RENAME_NORMAL = 0,
 +      RENAME_DIR,
        RENAME_DELETE,
        RENAME_ONE_FILE_TO_ONE,
        RENAME_ONE_FILE_TO_TWO,
@@@ -286,12 -224,10 +287,12 @@@ static void output(struct merge_option
  
  static void output_commit_title(struct merge_options *o, struct commit *commit)
  {
 +      struct merge_remote_desc *desc;
 +
        strbuf_addchars(&o->obuf, ' ', o->call_depth * 2);
 -      if (commit->util)
 -              strbuf_addf(&o->obuf, "virtual %s\n",
 -                      merge_remote_util(commit)->name);
 +      desc = merge_remote_util(commit);
 +      if (desc)
 +              strbuf_addf(&o->obuf, "virtual %s\n", desc->name);
        else {
                strbuf_add_unique_abbrev(&o->obuf, &commit->object.oid,
                                         DEFAULT_ABBREV);
@@@ -319,7 -255,7 +320,7 @@@ static int add_cacheinfo(struct merge_o
  
        ce = make_cache_entry(mode, oid ? oid->hash : null_sha1, path, stage, 0);
        if (!ce)
 -              return err(o, _("addinfo_cache failed for path '%s'"), path);
 +              return err(o, _("add_cacheinfo failed for path '%s'; merge aborting."), path);
  
        ret = add_cache_entry(ce, options);
        if (refresh) {
  
                nce = refresh_cache_entry(ce, CE_MATCH_REFRESH | CE_MATCH_IGNORE_MISSING);
                if (!nce)
 -                      return err(o, _("addinfo_cache failed for path '%s'"), path);
 +                      return err(o, _("add_cacheinfo failed to refresh for path '%s'; merge aborting."), path);
                if (nce != ce)
                        ret = add_cache_entry(nce, options);
        }
@@@ -340,54 -276,36 +341,54 @@@ static void init_tree_desc_from_tree(st
        init_tree_desc(desc, tree->buffer, tree->size);
  }
  
 -static int git_merge_trees(int index_only,
 -                         struct tree *common,
 -                         struct tree *head,
 -                         struct tree *merge)
 +static int unpack_trees_start(struct merge_options *o,
 +                            struct tree *common,
 +                            struct tree *head,
 +                            struct tree *merge)
  {
        int rc;
        struct tree_desc t[3];
 -      struct unpack_trees_options opts;
 +      struct index_state tmp_index = { NULL };
  
 -      memset(&opts, 0, sizeof(opts));
 -      if (index_only)
 -              opts.index_only = 1;
 +      memset(&o->unpack_opts, 0, sizeof(o->unpack_opts));
 +      if (o->call_depth)
 +              o->unpack_opts.index_only = 1;
        else
 -              opts.update = 1;
 -      opts.merge = 1;
 -      opts.head_idx = 2;
 -      opts.fn = threeway_merge;
 -      opts.src_index = &the_index;
 -      opts.dst_index = &the_index;
 -      setup_unpack_trees_porcelain(&opts, "merge");
 +              o->unpack_opts.update = 1;
 +      o->unpack_opts.merge = 1;
 +      o->unpack_opts.head_idx = 2;
 +      o->unpack_opts.fn = threeway_merge;
 +      o->unpack_opts.src_index = &the_index;
 +      o->unpack_opts.dst_index = &tmp_index;
 +      o->unpack_opts.aggressive = !merge_detect_rename(o);
 +      setup_unpack_trees_porcelain(&o->unpack_opts, "merge");
  
        init_tree_desc_from_tree(t+0, common);
        init_tree_desc_from_tree(t+1, head);
        init_tree_desc_from_tree(t+2, merge);
  
 -      rc = unpack_trees(3, t, &opts);
 +      rc = unpack_trees(3, t, &o->unpack_opts);
        cache_tree_free(&active_cache_tree);
 +
 +      /*
 +       * Update the_index to match the new results, AFTER saving a copy
 +       * in o->orig_index.  Update src_index to point to the saved copy.
 +       * (verify_uptodate() checks src_index, and the original index is
 +       * the one that had the necessary modification timestamps.)
 +       */
 +      o->orig_index = the_index;
 +      the_index = tmp_index;
 +      o->unpack_opts.src_index = &o->orig_index;
 +
        return rc;
  }
  
 +static void unpack_trees_finish(struct merge_options *o)
 +{
 +      discard_index(&o->orig_index);
 +      clear_unpack_trees_porcelain(&o->unpack_opts);
 +}
 +
  struct tree *write_tree_from_memory(struct merge_options *o)
  {
        struct tree *result = NULL;
                                fprintf(stderr, "BUG: %d %.*s\n", ce_stage(ce),
                                        (int)ce_namelen(ce), ce->name);
                }
 -              die("BUG: unmerged index entries in merge-recursive.c");
 +              BUG("unmerged index entries in merge-recursive.c");
        }
  
        if (!active_cache_tree)
@@@ -443,21 -361,6 +444,21 @@@ static void get_files_dirs(struct merge
        read_tree_recursive(tree, "", 0, 0, &match_all, save_files_dirs, o);
  }
  
 +static int get_tree_entry_if_blob(const struct object_id *tree,
 +                                const char *path,
 +                                struct object_id *hashy,
 +                                unsigned int *mode_o)
 +{
 +      int ret;
 +
 +      ret = get_tree_entry(tree, path, hashy, mode_o);
 +      if (S_ISDIR(*mode_o)) {
 +              oidcpy(hashy, &null_oid);
 +              *mode_o = 0;
 +      }
 +      return ret;
 +}
 +
  /*
   * Returns an index_entry instance which doesn't have to correspond to
   * a real cache entry in Git's index.
@@@ -468,12 -371,12 +469,12 @@@ static struct stage_data *insert_stage_
  {
        struct string_list_item *item;
        struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
 -      get_tree_entry(&o->object.oid, path,
 -                      &e->stages[1].oid, &e->stages[1].mode);
 -      get_tree_entry(&a->object.oid, path,
 -                      &e->stages[2].oid, &e->stages[2].mode);
 -      get_tree_entry(&b->object.oid, path,
 -                      &e->stages[3].oid, &e->stages[3].mode);
 +      get_tree_entry_if_blob(&o->object.oid, path,
 +                             &e->stages[1].oid, &e->stages[1].mode);
 +      get_tree_entry_if_blob(&a->object.oid, path,
 +                             &e->stages[2].oid, &e->stages[2].mode);
 +      get_tree_entry_if_blob(&b->object.oid, path,
 +                             &e->stages[3].oid, &e->stages[3].mode);
        item = string_list_insert(entries, path);
        item->util = e;
        return e;
@@@ -632,10 -535,78 +633,10 @@@ struct rename 
         */
        struct stage_data *src_entry;
        struct stage_data *dst_entry;
 +      unsigned add_turned_into_rename:1;
        unsigned processed:1;
  };
  
 -/*
 - * Get information of all renames which occurred between 'o_tree' and
 - * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
 - * 'b_tree') to be able to associate the correct cache entries with
 - * the rename information. 'tree' is always equal to either a_tree or b_tree.
 - */
 -static struct string_list *get_renames(struct merge_options *o,
 -                                     struct tree *tree,
 -                                     struct tree *o_tree,
 -                                     struct tree *a_tree,
 -                                     struct tree *b_tree,
 -                                     struct string_list *entries)
 -{
 -      int i;
 -      struct string_list *renames;
 -      struct diff_options opts;
 -
 -      renames = xcalloc(1, sizeof(struct string_list));
 -      if (!o->detect_rename)
 -              return renames;
 -
 -      diff_setup(&opts);
 -      opts.flags.recursive = 1;
 -      opts.flags.rename_empty = 0;
 -      opts.detect_rename = DIFF_DETECT_RENAME;
 -      opts.rename_limit = o->merge_rename_limit >= 0 ? o->merge_rename_limit :
 -                          o->diff_rename_limit >= 0 ? o->diff_rename_limit :
 -                          1000;
 -      opts.rename_score = o->rename_score;
 -      opts.show_rename_progress = o->show_rename_progress;
 -      opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 -      diff_setup_done(&opts);
 -      diff_tree_oid(&o_tree->object.oid, &tree->object.oid, "", &opts);
 -      diffcore_std(&opts);
 -      if (opts.needed_rename_limit > o->needed_rename_limit)
 -              o->needed_rename_limit = opts.needed_rename_limit;
 -      for (i = 0; i < diff_queued_diff.nr; ++i) {
 -              struct string_list_item *item;
 -              struct rename *re;
 -              struct diff_filepair *pair = diff_queued_diff.queue[i];
 -              if (pair->status != 'R') {
 -                      diff_free_filepair(pair);
 -                      continue;
 -              }
 -              re = xmalloc(sizeof(*re));
 -              re->processed = 0;
 -              re->pair = pair;
 -              item = string_list_lookup(entries, re->pair->one->path);
 -              if (!item)
 -                      re->src_entry = insert_stage_data(re->pair->one->path,
 -                                      o_tree, a_tree, b_tree, entries);
 -              else
 -                      re->src_entry = item->util;
 -
 -              item = string_list_lookup(entries, re->pair->two->path);
 -              if (!item)
 -                      re->dst_entry = insert_stage_data(re->pair->two->path,
 -                                      o_tree, a_tree, b_tree, entries);
 -              else
 -                      re->dst_entry = item->util;
 -              item = string_list_insert(renames, pair->one->path);
 -              item->util = re;
 -      }
 -      opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 -      diff_queued_diff.nr = 0;
 -      diff_flush(&opts);
 -      return renames;
 -}
 -
  static int update_stages(struct merge_options *opt, const char *path,
                         const struct diff_filespec *o,
                         const struct diff_filespec *a,
        return 0;
  }
  
 +static int update_stages_for_stage_data(struct merge_options *opt,
 +                                      const char *path,
 +                                      const struct stage_data *stage_data)
 +{
 +      struct diff_filespec o, a, b;
 +
 +      o.mode = stage_data->stages[1].mode;
 +      oidcpy(&o.oid, &stage_data->stages[1].oid);
 +
 +      a.mode = stage_data->stages[2].mode;
 +      oidcpy(&a.oid, &stage_data->stages[2].oid);
 +
 +      b.mode = stage_data->stages[3].mode;
 +      oidcpy(&b.oid, &stage_data->stages[3].oid);
 +
 +      return update_stages(opt, path,
 +                           is_null_oid(&o.oid) ? NULL : &o,
 +                           is_null_oid(&a.oid) ? NULL : &a,
 +                           is_null_oid(&b.oid) ? NULL : &b);
 +}
 +
  static void update_entry(struct stage_data *entry,
                         struct diff_filespec *o,
                         struct diff_filespec *a,
@@@ -789,92 -739,31 +790,92 @@@ static int dir_in_way(const char *path
                !(empty_ok && is_empty_dir(path));
  }
  
 -static int was_tracked(const char *path)
 +/*
 + * Returns whether path was tracked in the index before the merge started,
 + * and its oid and mode match the specified values
 + */
 +static int was_tracked_and_matches(struct merge_options *o, const char *path,
 +                                 const struct object_id *oid, unsigned mode)
  {
 -      int pos = cache_name_pos(path, strlen(path));
 +      int pos = index_name_pos(&o->orig_index, path, strlen(path));
 +      struct cache_entry *ce;
 +
 +      if (0 > pos)
 +              /* we were not tracking this path before the merge */
 +              return 0;
 +
 +      /* See if the file we were tracking before matches */
 +      ce = o->orig_index.cache[pos];
 +      return (oid_eq(&ce->oid, oid) && ce->ce_mode == mode);
 +}
 +
 +/*
 + * Returns whether path was tracked in the index before the merge started
 + */
 +static int was_tracked(struct merge_options *o, const char *path)
 +{
 +      int pos = index_name_pos(&o->orig_index, path, strlen(path));
  
        if (0 <= pos)
 -              /* we have been tracking this path */
 +              /* we were tracking this path before the merge */
                return 1;
  
 -      /*
 -       * Look for an unmerged entry for the path,
 -       * specifically stage #2, which would indicate
 -       * that "our" side before the merge started
 -       * had the path tracked (and resulted in a conflict).
 -       */
 -      for (pos = -1 - pos;
 -           pos < active_nr && !strcmp(path, active_cache[pos]->name);
 -           pos++)
 -              if (ce_stage(active_cache[pos]) == 2)
 -                      return 1;
        return 0;
  }
  
  static int would_lose_untracked(const char *path)
  {
 -      return !was_tracked(path) && file_exists(path);
 +      /*
 +       * This may look like it can be simplified to:
 +       *   return !was_tracked(o, path) && file_exists(path)
 +       * but it can't.  This function needs to know whether path was in
 +       * the working tree due to EITHER having been tracked in the index
 +       * before the merge OR having been put into the working copy and
 +       * index by unpack_trees().  Due to that either-or requirement, we
 +       * check the current index instead of the original one.
 +       *
 +       * Note that we do not need to worry about merge-recursive itself
 +       * updating the index after unpack_trees() and before calling this
 +       * function, because we strictly require all code paths in
 +       * merge-recursive to update the working tree first and the index
 +       * second.  Doing otherwise would break
 +       * update_file()/would_lose_untracked(); see every comment in this
 +       * file which mentions "update_stages".
 +       */
 +      int pos = cache_name_pos(path, strlen(path));
 +
 +      if (pos < 0)
 +              pos = -1 - pos;
 +      while (pos < active_nr &&
 +             !strcmp(path, active_cache[pos]->name)) {
 +              /*
 +               * If stage #0, it is definitely tracked.
 +               * If it has stage #2 then it was tracked
 +               * before this merge started.  All other
 +               * cases the path was not tracked.
 +               */
 +              switch (ce_stage(active_cache[pos])) {
 +              case 0:
 +              case 2:
 +                      return 0;
 +              }
 +              pos++;
 +      }
 +      return file_exists(path);
 +}
 +
 +static int was_dirty(struct merge_options *o, const char *path)
 +{
 +      struct cache_entry *ce;
 +      int dirty = 1;
 +
 +      if (o->call_depth || !was_tracked(o, path))
 +              return !dirty;
 +
 +      ce = index_file_exists(o->unpack_opts.src_index,
 +                             path, strlen(path), ignore_case);
 +      dirty = verify_uptodate(ce, &o->unpack_opts) != 0;
 +      return dirty;
  }
  
  static int make_room_for_path(struct merge_options *o, const char *path)
@@@ -1005,9 -894,7 +1006,9 @@@ static int update_file_flags(struct mer
        }
   update_index:
        if (!ret && update_cache)
 -              add_cacheinfo(o, mode, oid, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
 +              if (add_cacheinfo(o, mode, oid, path, 0, update_wd,
 +                                ADD_CACHE_OK_TO_ADD))
 +                      return -1;
        return ret;
  }
  
@@@ -1091,193 -978,13 +1092,193 @@@ static int merge_3way(struct merge_opti
        return merge_status;
  }
  
 +static int find_first_merges(struct object_array *result, const char *path,
 +              struct commit *a, struct commit *b)
 +{
 +      int i, j;
 +      struct object_array merges = OBJECT_ARRAY_INIT;
 +      struct commit *commit;
 +      int contains_another;
 +
 +      char merged_revision[42];
 +      const char *rev_args[] = { "rev-list", "--merges", "--ancestry-path",
 +                                 "--all", merged_revision, NULL };
 +      struct rev_info revs;
 +      struct setup_revision_opt rev_opts;
 +
 +      memset(result, 0, sizeof(struct object_array));
 +      memset(&rev_opts, 0, sizeof(rev_opts));
 +
 +      /* get all revisions that merge commit a */
 +      xsnprintf(merged_revision, sizeof(merged_revision), "^%s",
 +                      oid_to_hex(&a->object.oid));
 +      init_revisions(&revs, NULL);
 +      rev_opts.submodule = path;
 +      /* FIXME: can't handle linked worktrees in submodules yet */
 +      revs.single_worktree = path != NULL;
 +      setup_revisions(ARRAY_SIZE(rev_args)-1, rev_args, &revs, &rev_opts);
 +
 +      /* save all revisions from the above list that contain b */
 +      if (prepare_revision_walk(&revs))
 +              die("revision walk setup failed");
 +      while ((commit = get_revision(&revs)) != NULL) {
 +              struct object *o = &(commit->object);
 +              if (in_merge_bases(b, commit))
 +                      add_object_array(o, NULL, &merges);
 +      }
 +      reset_revision_walk();
 +
 +      /* Now we've got all merges that contain a and b. Prune all
 +       * merges that contain another found merge and save them in
 +       * result.
 +       */
 +      for (i = 0; i < merges.nr; i++) {
 +              struct commit *m1 = (struct commit *) merges.objects[i].item;
 +
 +              contains_another = 0;
 +              for (j = 0; j < merges.nr; j++) {
 +                      struct commit *m2 = (struct commit *) merges.objects[j].item;
 +                      if (i != j && in_merge_bases(m2, m1)) {
 +                              contains_another = 1;
 +                              break;
 +                      }
 +              }
 +
 +              if (!contains_another)
 +                      add_object_array(merges.objects[i].item, NULL, result);
 +      }
 +
 +      object_array_clear(&merges);
 +      return result->nr;
 +}
 +
 +static void print_commit(struct commit *commit)
 +{
 +      struct strbuf sb = STRBUF_INIT;
 +      struct pretty_print_context ctx = {0};
 +      ctx.date_mode.type = DATE_NORMAL;
 +      format_commit_message(commit, " %h: %m %s", &sb, &ctx);
 +      fprintf(stderr, "%s\n", sb.buf);
 +      strbuf_release(&sb);
 +}
 +
 +static int merge_submodule(struct merge_options *o,
 +                         struct object_id *result, const char *path,
 +                         const struct object_id *base, const struct object_id *a,
 +                         const struct object_id *b)
 +{
 +      struct commit *commit_base, *commit_a, *commit_b;
 +      int parent_count;
 +      struct object_array merges;
 +
 +      int i;
 +      int search = !o->call_depth;
 +
 +      /* store a in result in case we fail */
 +      oidcpy(result, a);
 +
 +      /* we can not handle deletion conflicts */
 +      if (is_null_oid(base))
 +              return 0;
 +      if (is_null_oid(a))
 +              return 0;
 +      if (is_null_oid(b))
 +              return 0;
 +
 +      if (add_submodule_odb(path)) {
 +              output(o, 1, _("Failed to merge submodule %s (not checked out)"), path);
 +              return 0;
 +      }
 +
 +      if (!(commit_base = lookup_commit_reference(base)) ||
 +          !(commit_a = lookup_commit_reference(a)) ||
 +          !(commit_b = lookup_commit_reference(b))) {
 +              output(o, 1, _("Failed to merge submodule %s (commits not present)"), path);
 +              return 0;
 +      }
 +
 +      /* check whether both changes are forward */
 +      if (!in_merge_bases(commit_base, commit_a) ||
 +          !in_merge_bases(commit_base, commit_b)) {
 +              output(o, 1, _("Failed to merge submodule %s (commits don't follow merge-base)"), path);
 +              return 0;
 +      }
 +
 +      /* Case #1: a is contained in b or vice versa */
 +      if (in_merge_bases(commit_a, commit_b)) {
 +              oidcpy(result, b);
 +              if (show(o, 3)) {
 +                      output(o, 3, _("Fast-forwarding submodule %s to the following commit:"), path);
 +                      output_commit_title(o, commit_b);
 +              } else if (show(o, 2))
 +                      output(o, 2, _("Fast-forwarding submodule %s"), path);
 +              else
 +                      ; /* no output */
 +
 +              return 1;
 +      }
 +      if (in_merge_bases(commit_b, commit_a)) {
 +              oidcpy(result, a);
 +              if (show(o, 3)) {
 +                      output(o, 3, _("Fast-forwarding submodule %s to the following commit:"), path);
 +                      output_commit_title(o, commit_a);
 +              } else if (show(o, 2))
 +                      output(o, 2, _("Fast-forwarding submodule %s"), path);
 +              else
 +                      ; /* no output */
 +
 +              return 1;
 +      }
 +
 +      /*
 +       * Case #2: There are one or more merges that contain a and b in
 +       * the submodule. If there is only one, then present it as a
 +       * suggestion to the user, but leave it marked unmerged so the
 +       * user needs to confirm the resolution.
 +       */
 +
 +      /* Skip the search if makes no sense to the calling context.  */
 +      if (!search)
 +              return 0;
 +
 +      /* find commit which merges them */
 +      parent_count = find_first_merges(&merges, path, commit_a, commit_b);
 +      switch (parent_count) {
 +      case 0:
 +              output(o, 1, _("Failed to merge submodule %s (merge following commits not found)"), path);
 +              break;
 +
 +      case 1:
 +              output(o, 1, _("Failed to merge submodule %s (not fast-forward)"), path);
 +              output(o, 2, _("Found a possible merge resolution for the submodule:\n"));
 +              print_commit((struct commit *) merges.objects[0].item);
 +              output(o, 2, _(
 +                      "If this is correct simply add it to the index "
 +                      "for example\n"
 +                      "by using:\n\n"
 +                      "  git update-index --cacheinfo 160000 %s \"%s\"\n\n"
 +                      "which will accept this suggestion.\n"),
 +                      oid_to_hex(&merges.objects[0].item->oid), path);
 +              break;
 +
 +      default:
 +              output(o, 1, _("Failed to merge submodule %s (multiple merges found)"), path);
 +              for (i = 0; i < merges.nr; i++)
 +                      print_commit((struct commit *) merges.objects[i].item);
 +      }
 +
 +      object_array_clear(&merges);
 +      return 0;
 +}
 +
  static int merge_file_1(struct merge_options *o,
 -                                         const struct diff_filespec *one,
 -                                         const struct diff_filespec *a,
 -                                         const struct diff_filespec *b,
 -                                         const char *branch1,
 -                                         const char *branch2,
 -                                         struct merge_file_info *result)
 +                      const struct diff_filespec *one,
 +                      const struct diff_filespec *a,
 +                      const struct diff_filespec *b,
 +                      const char *filename,
 +                      const char *branch1,
 +                      const char *branch2,
 +                      struct merge_file_info *result)
  {
        result->merge = 0;
        result->clean = 1;
                                return ret;
                        result->clean = (merge_status == 0);
                } else if (S_ISGITLINK(a->mode)) {
 -                      result->clean = merge_submodule(&result->oid,
 +                      result->clean = merge_submodule(o, &result->oid,
                                                       one->path,
                                                       &one->oid,
                                                       &a->oid,
 -                                                     &b->oid,
 -                                                     !o->call_depth);
 +                                                     &b->oid);
                } else if (S_ISLNK(a->mode)) {
                        switch (o->recursive_variant) {
                        case MERGE_RECURSIVE_NORMAL:
                                break;
                        }
                } else
 -                      die("BUG: unsupported object type in the tree");
 +                      BUG("unsupported object type in the tree");
        }
  
 +      if (result->merge)
 +              output(o, 2, _("Auto-merging %s"), filename);
 +
        return 0;
  }
  
  static int merge_file_special_markers(struct merge_options *o,
 -                         const struct diff_filespec *one,
 -                         const struct diff_filespec *a,
 -                         const struct diff_filespec *b,
 -                         const char *branch1,
 -                         const char *filename1,
 -                         const char *branch2,
 -                         const char *filename2,
 -                         struct merge_file_info *mfi)
 +                                    const struct diff_filespec *one,
 +                                    const struct diff_filespec *a,
 +                                    const struct diff_filespec *b,
 +                                    const char *target_filename,
 +                                    const char *branch1,
 +                                    const char *filename1,
 +                                    const char *branch2,
 +                                    const char *filename2,
 +                                    struct merge_file_info *mfi)
  {
        char *side1 = NULL;
        char *side2 = NULL;
        if (filename2)
                side2 = xstrfmt("%s:%s", branch2, filename2);
  
 -      ret = merge_file_1(o, one, a, b,
 +      ret = merge_file_1(o, one, a, b, target_filename,
                           side1 ? side1 : branch1,
                           side2 ? side2 : branch2, mfi);
 +
        free(side1);
        free(side2);
        return ret;
  }
  
  static int merge_file_one(struct merge_options *o,
 -                                       const char *path,
 -                                       const struct object_id *o_oid, int o_mode,
 -                                       const struct object_id *a_oid, int a_mode,
 -                                       const struct object_id *b_oid, int b_mode,
 -                                       const char *branch1,
 -                                       const char *branch2,
 -                                       struct merge_file_info *mfi)
 +                        const char *path,
 +                        const struct object_id *o_oid, int o_mode,
 +                        const struct object_id *a_oid, int a_mode,
 +                        const struct object_id *b_oid, int b_mode,
 +                        const char *branch1,
 +                        const char *branch2,
 +                        struct merge_file_info *mfi)
  {
        struct diff_filespec one, a, b;
  
        a.mode = a_mode;
        oidcpy(&b.oid, b_oid);
        b.mode = b_mode;
 -      return merge_file_1(o, &one, &a, &b, branch1, branch2, mfi);
 +      return merge_file_1(o, &one, &a, &b, path, branch1, branch2, mfi);
 +}
 +
 +static int conflict_rename_dir(struct merge_options *o,
 +                             struct diff_filepair *pair,
 +                             const char *rename_branch,
 +                             const char *other_branch)
 +{
 +      const struct diff_filespec *dest = pair->two;
 +
 +      if (!o->call_depth && would_lose_untracked(dest->path)) {
 +              char *alt_path = unique_path(o, dest->path, rename_branch);
 +
 +              output(o, 1, _("Error: Refusing to lose untracked file at %s; "
 +                             "writing to %s instead."),
 +                     dest->path, alt_path);
 +              /*
 +               * Write the file in worktree at alt_path, but not in the
 +               * index.  Instead, write to dest->path for the index but
 +               * only at the higher appropriate stage.
 +               */
 +              if (update_file(o, 0, &dest->oid, dest->mode, alt_path))
 +                      return -1;
 +              free(alt_path);
 +              return update_stages(o, dest->path, NULL,
 +                                   rename_branch == o->branch1 ? dest : NULL,
 +                                   rename_branch == o->branch1 ? NULL : dest);
 +      }
 +
 +      /* Update dest->path both in index and in worktree */
 +      if (update_file(o, 1, &dest->oid, dest->mode, dest->path))
 +              return -1;
 +      return 0;
  }
  
  static int handle_change_delete(struct merge_options *o,
        const char *update_path = path;
        int ret = 0;
  
 -      if (dir_in_way(path, !o->call_depth, 0)) {
 +      if (dir_in_way(path, !o->call_depth, 0) ||
 +          (!o->call_depth && would_lose_untracked(path))) {
                update_path = alt_path = unique_path(o, path, change_branch);
        }
  
@@@ -1573,34 -1243,17 +1574,34 @@@ static int handle_file(struct merge_opt
  
        add = filespec_from_entry(&other, dst_entry, stage ^ 1);
        if (add) {
 +              int ren_src_was_dirty = was_dirty(o, rename->path);
                char *add_name = unique_path(o, rename->path, other_branch);
                if (update_file(o, 0, &add->oid, add->mode, add_name))
                        return -1;
  
 -              remove_file(o, 0, rename->path, 0);
 +              if (ren_src_was_dirty) {
 +                      output(o, 1, _("Refusing to lose dirty file at %s"),
 +                             rename->path);
 +              }
 +              /*
 +               * Because the double negatives somehow keep confusing me...
 +               *    1) update_wd iff !ren_src_was_dirty.
 +               *    2) no_wd iff !update_wd
 +               *    3) so, no_wd == !!ren_src_was_dirty == ren_src_was_dirty
 +               */
 +              remove_file(o, 0, rename->path, ren_src_was_dirty);
                dst_name = unique_path(o, rename->path, cur_branch);
        } else {
                if (dir_in_way(rename->path, !o->call_depth, 0)) {
                        dst_name = unique_path(o, rename->path, cur_branch);
                        output(o, 1, _("%s is a directory in %s adding as %s instead"),
                               rename->path, other_branch, dst_name);
 +              } else if (!o->call_depth &&
 +                         would_lose_untracked(rename->path)) {
 +                      dst_name = unique_path(o, rename->path, cur_branch);
 +                      output(o, 1, _("Refusing to lose untracked file at %s; "
 +                                     "adding as %s instead"),
 +                             rename->path, dst_name);
                }
        }
        if ((ret = update_file(o, 0, &rename->oid, rename->mode, dst_name)))
@@@ -1687,8 -1340,6 +1688,8 @@@ static int conflict_rename_rename_2to1(
        struct diff_filespec *c1 = ci->pair1->two;
        struct diff_filespec *c2 = ci->pair2->two;
        char *path = c1->path; /* == c2->path */
 +      char *path_side_1_desc;
 +      char *path_side_2_desc;
        struct merge_file_info mfi_c1;
        struct merge_file_info mfi_c2;
        int ret;
        remove_file(o, 1, a->path, o->call_depth || would_lose_untracked(a->path));
        remove_file(o, 1, b->path, o->call_depth || would_lose_untracked(b->path));
  
 +      path_side_1_desc = xstrfmt("%s (was %s)", path, a->path);
 +      path_side_2_desc = xstrfmt("%s (was %s)", path, b->path);
        if (merge_file_special_markers(o, a, c1, &ci->ren1_other,
 +                                     path_side_1_desc,
                                       o->branch1, c1->path,
                                       o->branch2, ci->ren1_other.path, &mfi_c1) ||
            merge_file_special_markers(o, b, &ci->ren2_other, c2,
 +                                     path_side_2_desc,
                                       o->branch1, ci->ren2_other.path,
                                       o->branch2, c2->path, &mfi_c2))
                return -1;
 +      free(path_side_1_desc);
 +      free(path_side_2_desc);
  
        if (o->call_depth) {
                /*
                char *new_path2 = unique_path(o, path, ci->branch2);
                output(o, 1, _("Renaming %s to %s and %s to %s instead"),
                       a->path, new_path1, b->path, new_path2);
 -              remove_file(o, 0, path, 0);
 +              if (was_dirty(o, path))
 +                      output(o, 1, _("Refusing to lose dirty file at %s"),
 +                             path);
 +              else if (would_lose_untracked(path))
 +                      /*
 +                       * Only way we get here is if both renames were from
 +                       * a directory rename AND user had an untracked file
 +                       * at the location where both files end up after the
 +                       * two directory renames.  See testcase 10d of t6043.
 +                       */
 +                      output(o, 1, _("Refusing to lose untracked file at "
 +                                     "%s, even though it's in the way."),
 +                             path);
 +              else
 +                      remove_file(o, 0, path, 0);
                ret = update_file(o, 0, &mfi_c1.oid, mfi_c1.mode, new_path1);
                if (!ret)
                        ret = update_file(o, 0, &mfi_c2.oid, mfi_c2.mode,
                                          new_path2);
 +              /*
 +               * unpack_trees() actually populates the index for us for
 +               * "normal" rename/rename(2to1) situtations so that the
 +               * correct entries are at the higher stages, which would
 +               * make the call below to update_stages_for_stage_data
 +               * unnecessary.  However, if either of the renames came
 +               * from a directory rename, then unpack_trees() will not
 +               * have gotten the right data loaded into the index, so we
 +               * need to do so now.  (While it'd be tempting to move this
 +               * call to update_stages_for_stage_data() to
 +               * apply_directory_rename_modifications(), that would break
 +               * our intermediate calls to would_lose_untracked() since
 +               * those rely on the current in-memory index.  See also the
 +               * big "NOTE" in update_stages()).
 +               */
 +              if (update_stages_for_stage_data(o, path, ci->dst_entry1))
 +                      ret = -1;
 +
                free(new_path2);
                free(new_path1);
        }
        return ret;
  }
  
 -static int process_renames(struct merge_options *o,
 -                         struct string_list *a_renames,
 -                         struct string_list *b_renames)
 +/*
 + * Get the diff_filepairs changed between o_tree and tree.
 + */
 +static struct diff_queue_struct *get_diffpairs(struct merge_options *o,
 +                                             struct tree *o_tree,
 +                                             struct tree *tree)
  {
 -      int clean_merge = 1, i, j;
 -      struct string_list a_by_dst = STRING_LIST_INIT_NODUP;
 -      struct string_list b_by_dst = STRING_LIST_INIT_NODUP;
 -      const struct rename *sre;
 -
 -      for (i = 0; i < a_renames->nr; i++) {
 -              sre = a_renames->items[i].util;
 -              string_list_insert(&a_by_dst, sre->pair->two->path)->util
 -                      = (void *)sre;
 -      }
 -      for (i = 0; i < b_renames->nr; i++) {
 -              sre = b_renames->items[i].util;
 -              string_list_insert(&b_by_dst, sre->pair->two->path)->util
 -                      = (void *)sre;
 -      }
 -
 -      for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
 -              struct string_list *renames1, *renames2Dst;
 -              struct rename *ren1 = NULL, *ren2 = NULL;
 -              const char *branch1, *branch2;
 -              const char *ren1_src, *ren1_dst;
 -              struct string_list_item *lookup;
 +      struct diff_queue_struct *ret;
 +      struct diff_options opts;
  
 -              if (i >= a_renames->nr) {
 -                      ren2 = b_renames->items[j++].util;
 -              } else if (j >= b_renames->nr) {
 -                      ren1 = a_renames->items[i++].util;
 -              } else {
 -                      int compare = strcmp(a_renames->items[i].string,
 -                                           b_renames->items[j].string);
 +      diff_setup(&opts);
 +      opts.flags.recursive = 1;
 +      opts.flags.rename_empty = 0;
 +      opts.detect_rename = merge_detect_rename(o);
 +      /*
 +       * We do not have logic to handle the detection of copies.  In
 +       * fact, it may not even make sense to add such logic: would we
 +       * really want a change to a base file to be propagated through
 +       * multiple other files by a merge?
 +       */
 +      if (opts.detect_rename > DIFF_DETECT_RENAME)
 +              opts.detect_rename = DIFF_DETECT_RENAME;
 +      opts.rename_limit = o->merge_rename_limit >= 0 ? o->merge_rename_limit :
 +                          o->diff_rename_limit >= 0 ? o->diff_rename_limit :
 +                          1000;
 +      opts.rename_score = o->rename_score;
 +      opts.show_rename_progress = o->show_rename_progress;
 +      opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 +      diff_setup_done(&opts);
 +      diff_tree_oid(&o_tree->object.oid, &tree->object.oid, "", &opts);
 +      diffcore_std(&opts);
 +      if (opts.needed_rename_limit > o->needed_rename_limit)
 +              o->needed_rename_limit = opts.needed_rename_limit;
 +
 +      ret = xmalloc(sizeof(*ret));
 +      *ret = diff_queued_diff;
 +
 +      opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 +      diff_queued_diff.nr = 0;
 +      diff_queued_diff.queue = NULL;
 +      diff_flush(&opts);
 +      return ret;
 +}
 +
 +static int tree_has_path(struct tree *tree, const char *path)
 +{
 +      struct object_id hashy;
 +      unsigned int mode_o;
 +
 +      return !get_tree_entry(&tree->object.oid, path,
 +                             &hashy, &mode_o);
 +}
 +
 +/*
 + * Return a new string that replaces the beginning portion (which matches
 + * entry->dir), with entry->new_dir.  In perl-speak:
 + *   new_path_name = (old_path =~ s/entry->dir/entry->new_dir/);
 + * NOTE:
 + *   Caller must ensure that old_path starts with entry->dir + '/'.
 + */
 +static char *apply_dir_rename(struct dir_rename_entry *entry,
 +                            const char *old_path)
 +{
 +      struct strbuf new_path = STRBUF_INIT;
 +      int oldlen, newlen;
 +
 +      if (entry->non_unique_new_dir)
 +              return NULL;
 +
 +      oldlen = strlen(entry->dir);
 +      newlen = entry->new_dir.len + (strlen(old_path) - oldlen) + 1;
 +      strbuf_grow(&new_path, newlen);
 +      strbuf_addbuf(&new_path, &entry->new_dir);
 +      strbuf_addstr(&new_path, &old_path[oldlen]);
 +
 +      return strbuf_detach(&new_path, NULL);
 +}
 +
 +static void get_renamed_dir_portion(const char *old_path, const char *new_path,
 +                                  char **old_dir, char **new_dir)
 +{
 +      char *end_of_old, *end_of_new;
 +      int old_len, new_len;
 +
 +      *old_dir = NULL;
 +      *new_dir = NULL;
 +
 +      /*
 +       * For
 +       *    "a/b/c/d/e/foo.c" -> "a/b/some/thing/else/e/foo.c"
 +       * the "e/foo.c" part is the same, we just want to know that
 +       *    "a/b/c/d" was renamed to "a/b/some/thing/else"
 +       * so, for this example, this function returns "a/b/c/d" in
 +       * *old_dir and "a/b/some/thing/else" in *new_dir.
 +       *
 +       * Also, if the basename of the file changed, we don't care.  We
 +       * want to know which portion of the directory, if any, changed.
 +       */
 +      end_of_old = strrchr(old_path, '/');
 +      end_of_new = strrchr(new_path, '/');
 +
 +      if (end_of_old == NULL || end_of_new == NULL)
 +              return;
 +      while (*--end_of_new == *--end_of_old &&
 +             end_of_old != old_path &&
 +             end_of_new != new_path)
 +              ; /* Do nothing; all in the while loop */
 +      /*
 +       * We've found the first non-matching character in the directory
 +       * paths.  That means the current directory we were comparing
 +       * represents the rename.  Move end_of_old and end_of_new back
 +       * to the full directory name.
 +       */
 +      if (*end_of_old == '/')
 +              end_of_old++;
 +      if (*end_of_old != '/')
 +              end_of_new++;
 +      end_of_old = strchr(end_of_old, '/');
 +      end_of_new = strchr(end_of_new, '/');
 +
 +      /*
 +       * It may have been the case that old_path and new_path were the same
 +       * directory all along.  Don't claim a rename if they're the same.
 +       */
 +      old_len = end_of_old - old_path;
 +      new_len = end_of_new - new_path;
 +
 +      if (old_len != new_len || strncmp(old_path, new_path, old_len)) {
 +              *old_dir = xstrndup(old_path, old_len);
 +              *new_dir = xstrndup(new_path, new_len);
 +      }
 +}
 +
 +static void remove_hashmap_entries(struct hashmap *dir_renames,
 +                                 struct string_list *items_to_remove)
 +{
 +      int i;
 +      struct dir_rename_entry *entry;
 +
 +      for (i = 0; i < items_to_remove->nr; i++) {
 +              entry = items_to_remove->items[i].util;
 +              hashmap_remove(dir_renames, entry, NULL);
 +      }
 +      string_list_clear(items_to_remove, 0);
 +}
 +
 +/*
 + * See if there is a directory rename for path, and if there are any file
 + * level conflicts for the renamed location.  If there is a rename and
 + * there are no conflicts, return the new name.  Otherwise, return NULL.
 + */
 +static char *handle_path_level_conflicts(struct merge_options *o,
 +                                       const char *path,
 +                                       struct dir_rename_entry *entry,
 +                                       struct hashmap *collisions,
 +                                       struct tree *tree)
 +{
 +      char *new_path = NULL;
 +      struct collision_entry *collision_ent;
 +      int clean = 1;
 +      struct strbuf collision_paths = STRBUF_INIT;
 +
 +      /*
 +       * entry has the mapping of old directory name to new directory name
 +       * that we want to apply to path.
 +       */
 +      new_path = apply_dir_rename(entry, path);
 +
 +      if (!new_path) {
 +              /* This should only happen when entry->non_unique_new_dir set */
 +              if (!entry->non_unique_new_dir)
 +                      BUG("entry->non_unqiue_dir not set and !new_path");
 +              output(o, 1, _("CONFLICT (directory rename split): "
 +                             "Unclear where to place %s because directory "
 +                             "%s was renamed to multiple other directories, "
 +                             "with no destination getting a majority of the "
 +                             "files."),
 +                     path, entry->dir);
 +              clean = 0;
 +              return NULL;
 +      }
 +
 +      /*
 +       * The caller needs to have ensured that it has pre-populated
 +       * collisions with all paths that map to new_path.  Do a quick check
 +       * to ensure that's the case.
 +       */
 +      collision_ent = collision_find_entry(collisions, new_path);
 +      if (collision_ent == NULL)
 +              BUG("collision_ent is NULL");
 +
 +      /*
 +       * Check for one-sided add/add/.../add conflicts, i.e.
 +       * where implicit renames from the other side doing
 +       * directory rename(s) can affect this side of history
 +       * to put multiple paths into the same location.  Warn
 +       * and bail on directory renames for such paths.
 +       */
 +      if (collision_ent->reported_already) {
 +              clean = 0;
 +      } else if (tree_has_path(tree, new_path)) {
 +              collision_ent->reported_already = 1;
 +              strbuf_add_separated_string_list(&collision_paths, ", ",
 +                                               &collision_ent->source_files);
 +              output(o, 1, _("CONFLICT (implicit dir rename): Existing "
 +                             "file/dir at %s in the way of implicit "
 +                             "directory rename(s) putting the following "
 +                             "path(s) there: %s."),
 +                     new_path, collision_paths.buf);
 +              clean = 0;
 +      } else if (collision_ent->source_files.nr > 1) {
 +              collision_ent->reported_already = 1;
 +              strbuf_add_separated_string_list(&collision_paths, ", ",
 +                                               &collision_ent->source_files);
 +              output(o, 1, _("CONFLICT (implicit dir rename): Cannot map "
 +                             "more than one path to %s; implicit directory "
 +                             "renames tried to put these paths there: %s"),
 +                     new_path, collision_paths.buf);
 +              clean = 0;
 +      }
 +
 +      /* Free memory we no longer need */
 +      strbuf_release(&collision_paths);
 +      if (!clean && new_path) {
 +              free(new_path);
 +              return NULL;
 +      }
 +
 +      return new_path;
 +}
 +
 +/*
 + * There are a couple things we want to do at the directory level:
 + *   1. Check for both sides renaming to the same thing, in order to avoid
 + *      implicit renaming of files that should be left in place.  (See
 + *      testcase 6b in t6043 for details.)
 + *   2. Prune directory renames if there are still files left in the
 + *      the original directory.  These represent a partial directory rename,
 + *      i.e. a rename where only some of the files within the directory
 + *      were renamed elsewhere.  (Technically, this could be done earlier
 + *      in get_directory_renames(), except that would prevent us from
 + *      doing the previous check and thus failing testcase 6b.)
 + *   3. Check for rename/rename(1to2) conflicts (at the directory level).
 + *      In the future, we could potentially record this info as well and
 + *      omit reporting rename/rename(1to2) conflicts for each path within
 + *      the affected directories, thus cleaning up the merge output.
 + *   NOTE: We do NOT check for rename/rename(2to1) conflicts at the
 + *         directory level, because merging directories is fine.  If it
 + *         causes conflicts for files within those merged directories, then
 + *         that should be detected at the individual path level.
 + */
 +static void handle_directory_level_conflicts(struct merge_options *o,
 +                                           struct hashmap *dir_re_head,
 +                                           struct tree *head,
 +                                           struct hashmap *dir_re_merge,
 +                                           struct tree *merge)
 +{
 +      struct hashmap_iter iter;
 +      struct dir_rename_entry *head_ent;
 +      struct dir_rename_entry *merge_ent;
 +
 +      struct string_list remove_from_head = STRING_LIST_INIT_NODUP;
 +      struct string_list remove_from_merge = STRING_LIST_INIT_NODUP;
 +
 +      hashmap_iter_init(dir_re_head, &iter);
 +      while ((head_ent = hashmap_iter_next(&iter))) {
 +              merge_ent = dir_rename_find_entry(dir_re_merge, head_ent->dir);
 +              if (merge_ent &&
 +                  !head_ent->non_unique_new_dir &&
 +                  !merge_ent->non_unique_new_dir &&
 +                  !strbuf_cmp(&head_ent->new_dir, &merge_ent->new_dir)) {
 +                      /* 1. Renamed identically; remove it from both sides */
 +                      string_list_append(&remove_from_head,
 +                                         head_ent->dir)->util = head_ent;
 +                      strbuf_release(&head_ent->new_dir);
 +                      string_list_append(&remove_from_merge,
 +                                         merge_ent->dir)->util = merge_ent;
 +                      strbuf_release(&merge_ent->new_dir);
 +              } else if (tree_has_path(head, head_ent->dir)) {
 +                      /* 2. This wasn't a directory rename after all */
 +                      string_list_append(&remove_from_head,
 +                                         head_ent->dir)->util = head_ent;
 +                      strbuf_release(&head_ent->new_dir);
 +              }
 +      }
 +
 +      remove_hashmap_entries(dir_re_head, &remove_from_head);
 +      remove_hashmap_entries(dir_re_merge, &remove_from_merge);
 +
 +      hashmap_iter_init(dir_re_merge, &iter);
 +      while ((merge_ent = hashmap_iter_next(&iter))) {
 +              head_ent = dir_rename_find_entry(dir_re_head, merge_ent->dir);
 +              if (tree_has_path(merge, merge_ent->dir)) {
 +                      /* 2. This wasn't a directory rename after all */
 +                      string_list_append(&remove_from_merge,
 +                                         merge_ent->dir)->util = merge_ent;
 +              } else if (head_ent &&
 +                         !head_ent->non_unique_new_dir &&
 +                         !merge_ent->non_unique_new_dir) {
 +                      /* 3. rename/rename(1to2) */
 +                      /*
 +                       * We can assume it's not rename/rename(1to1) because
 +                       * that was case (1), already checked above.  So we
 +                       * know that head_ent->new_dir and merge_ent->new_dir
 +                       * are different strings.
 +                       */
 +                      output(o, 1, _("CONFLICT (rename/rename): "
 +                                     "Rename directory %s->%s in %s. "
 +                                     "Rename directory %s->%s in %s"),
 +                             head_ent->dir, head_ent->new_dir.buf, o->branch1,
 +                             head_ent->dir, merge_ent->new_dir.buf, o->branch2);
 +                      string_list_append(&remove_from_head,
 +                                         head_ent->dir)->util = head_ent;
 +                      strbuf_release(&head_ent->new_dir);
 +                      string_list_append(&remove_from_merge,
 +                                         merge_ent->dir)->util = merge_ent;
 +                      strbuf_release(&merge_ent->new_dir);
 +              }
 +      }
 +
 +      remove_hashmap_entries(dir_re_head, &remove_from_head);
 +      remove_hashmap_entries(dir_re_merge, &remove_from_merge);
 +}
 +
 +static struct hashmap *get_directory_renames(struct diff_queue_struct *pairs,
 +                                           struct tree *tree)
 +{
 +      struct hashmap *dir_renames;
 +      struct hashmap_iter iter;
 +      struct dir_rename_entry *entry;
 +      int i;
 +
 +      /*
 +       * Typically, we think of a directory rename as all files from a
 +       * certain directory being moved to a target directory.  However,
 +       * what if someone first moved two files from the original
 +       * directory in one commit, and then renamed the directory
 +       * somewhere else in a later commit?  At merge time, we just know
 +       * that files from the original directory went to two different
 +       * places, and that the bulk of them ended up in the same place.
 +       * We want each directory rename to represent where the bulk of the
 +       * files from that directory end up; this function exists to find
 +       * where the bulk of the files went.
 +       *
 +       * The first loop below simply iterates through the list of file
 +       * renames, finding out how often each directory rename pair
 +       * possibility occurs.
 +       */
 +      dir_renames = xmalloc(sizeof(*dir_renames));
 +      dir_rename_init(dir_renames);
 +      for (i = 0; i < pairs->nr; ++i) {
 +              struct string_list_item *item;
 +              int *count;
 +              struct diff_filepair *pair = pairs->queue[i];
 +              char *old_dir, *new_dir;
 +
 +              /* File not part of directory rename if it wasn't renamed */
 +              if (pair->status != 'R')
 +                      continue;
 +
 +              get_renamed_dir_portion(pair->one->path, pair->two->path,
 +                                      &old_dir,        &new_dir);
 +              if (!old_dir)
 +                      /* Directory didn't change at all; ignore this one. */
 +                      continue;
 +
 +              entry = dir_rename_find_entry(dir_renames, old_dir);
 +              if (!entry) {
 +                      entry = xmalloc(sizeof(*entry));
 +                      dir_rename_entry_init(entry, old_dir);
 +                      hashmap_put(dir_renames, entry);
 +              } else {
 +                      free(old_dir);
 +              }
 +              item = string_list_lookup(&entry->possible_new_dirs, new_dir);
 +              if (!item) {
 +                      item = string_list_insert(&entry->possible_new_dirs,
 +                                                new_dir);
 +                      item->util = xcalloc(1, sizeof(int));
 +              } else {
 +                      free(new_dir);
 +              }
 +              count = item->util;
 +              *count += 1;
 +      }
 +
 +      /*
 +       * For each directory with files moved out of it, we find out which
 +       * target directory received the most files so we can declare it to
 +       * be the "winning" target location for the directory rename.  This
 +       * winner gets recorded in new_dir.  If there is no winner
 +       * (multiple target directories received the same number of files),
 +       * we set non_unique_new_dir.  Once we've determined the winner (or
 +       * that there is no winner), we no longer need possible_new_dirs.
 +       */
 +      hashmap_iter_init(dir_renames, &iter);
 +      while ((entry = hashmap_iter_next(&iter))) {
 +              int max = 0;
 +              int bad_max = 0;
 +              char *best = NULL;
 +
 +              for (i = 0; i < entry->possible_new_dirs.nr; i++) {
 +                      int *count = entry->possible_new_dirs.items[i].util;
 +
 +                      if (*count == max)
 +                              bad_max = max;
 +                      else if (*count > max) {
 +                              max = *count;
 +                              best = entry->possible_new_dirs.items[i].string;
 +                      }
 +              }
 +              if (bad_max == max)
 +                      entry->non_unique_new_dir = 1;
 +              else {
 +                      assert(entry->new_dir.len == 0);
 +                      strbuf_addstr(&entry->new_dir, best);
 +              }
 +              /*
 +               * The relevant directory sub-portion of the original full
 +               * filepaths were xstrndup'ed before inserting into
 +               * possible_new_dirs, and instead of manually iterating the
 +               * list and free'ing each, just lie and tell
 +               * possible_new_dirs that it did the strdup'ing so that it
 +               * will free them for us.
 +               */
 +              entry->possible_new_dirs.strdup_strings = 1;
 +              string_list_clear(&entry->possible_new_dirs, 1);
 +      }
 +
 +      return dir_renames;
 +}
 +
 +static struct dir_rename_entry *check_dir_renamed(const char *path,
 +                                                struct hashmap *dir_renames)
 +{
 +      char *temp = xstrdup(path);
 +      char *end;
 +      struct dir_rename_entry *entry = NULL;;
 +
 +      while ((end = strrchr(temp, '/'))) {
 +              *end = '\0';
 +              entry = dir_rename_find_entry(dir_renames, temp);
 +              if (entry)
 +                      break;
 +      }
 +      free(temp);
 +      return entry;
 +}
 +
 +static void compute_collisions(struct hashmap *collisions,
 +                             struct hashmap *dir_renames,
 +                             struct diff_queue_struct *pairs)
 +{
 +      int i;
 +
 +      /*
 +       * Multiple files can be mapped to the same path due to directory
 +       * renames done by the other side of history.  Since that other
 +       * side of history could have merged multiple directories into one,
 +       * if our side of history added the same file basename to each of
 +       * those directories, then all N of them would get implicitly
 +       * renamed by the directory rename detection into the same path,
 +       * and we'd get an add/add/.../add conflict, and all those adds
 +       * from *this* side of history.  This is not representable in the
 +       * index, and users aren't going to easily be able to make sense of
 +       * it.  So we need to provide a good warning about what's
 +       * happening, and fall back to no-directory-rename detection
 +       * behavior for those paths.
 +       *
 +       * See testcases 9e and all of section 5 from t6043 for examples.
 +       */
 +      collision_init(collisions);
 +
 +      for (i = 0; i < pairs->nr; ++i) {
 +              struct dir_rename_entry *dir_rename_ent;
 +              struct collision_entry *collision_ent;
 +              char *new_path;
 +              struct diff_filepair *pair = pairs->queue[i];
 +
 +              if (pair->status != 'A' && pair->status != 'R')
 +                      continue;
 +              dir_rename_ent = check_dir_renamed(pair->two->path,
 +                                                 dir_renames);
 +              if (!dir_rename_ent)
 +                      continue;
 +
 +              new_path = apply_dir_rename(dir_rename_ent, pair->two->path);
 +              if (!new_path)
 +                      /*
 +                       * dir_rename_ent->non_unique_new_path is true, which
 +                       * means there is no directory rename for us to use,
 +                       * which means it won't cause us any additional
 +                       * collisions.
 +                       */
 +                      continue;
 +              collision_ent = collision_find_entry(collisions, new_path);
 +              if (!collision_ent) {
 +                      collision_ent = xcalloc(1,
 +                                              sizeof(struct collision_entry));
 +                      hashmap_entry_init(collision_ent, strhash(new_path));
 +                      hashmap_put(collisions, collision_ent);
 +                      collision_ent->target_file = new_path;
 +              } else {
 +                      free(new_path);
 +              }
 +              string_list_insert(&collision_ent->source_files,
 +                                 pair->two->path);
 +      }
 +}
 +
 +static char *check_for_directory_rename(struct merge_options *o,
 +                                      const char *path,
 +                                      struct tree *tree,
 +                                      struct hashmap *dir_renames,
 +                                      struct hashmap *dir_rename_exclusions,
 +                                      struct hashmap *collisions,
 +                                      int *clean_merge)
 +{
 +      char *new_path = NULL;
 +      struct dir_rename_entry *entry = check_dir_renamed(path, dir_renames);
 +      struct dir_rename_entry *oentry = NULL;
 +
 +      if (!entry)
 +              return new_path;
 +
 +      /*
 +       * This next part is a little weird.  We do not want to do an
 +       * implicit rename into a directory we renamed on our side, because
 +       * that will result in a spurious rename/rename(1to2) conflict.  An
 +       * example:
 +       *   Base commit: dumbdir/afile, otherdir/bfile
 +       *   Side 1:      smrtdir/afile, otherdir/bfile
 +       *   Side 2:      dumbdir/afile, dumbdir/bfile
 +       * Here, while working on Side 1, we could notice that otherdir was
 +       * renamed/merged to dumbdir, and change the diff_filepair for
 +       * otherdir/bfile into a rename into dumbdir/bfile.  However, Side
 +       * 2 will notice the rename from dumbdir to smrtdir, and do the
 +       * transitive rename to move it from dumbdir/bfile to
 +       * smrtdir/bfile.  That gives us bfile in dumbdir vs being in
 +       * smrtdir, a rename/rename(1to2) conflict.  We really just want
 +       * the file to end up in smrtdir.  And the way to achieve that is
 +       * to not let Side1 do the rename to dumbdir, since we know that is
 +       * the source of one of our directory renames.
 +       *
 +       * That's why oentry and dir_rename_exclusions is here.
 +       *
 +       * As it turns out, this also prevents N-way transient rename
 +       * confusion; See testcases 9c and 9d of t6043.
 +       */
 +      oentry = dir_rename_find_entry(dir_rename_exclusions, entry->new_dir.buf);
 +      if (oentry) {
 +              output(o, 1, _("WARNING: Avoiding applying %s -> %s rename "
 +                             "to %s, because %s itself was renamed."),
 +                     entry->dir, entry->new_dir.buf, path, entry->new_dir.buf);
 +      } else {
 +              new_path = handle_path_level_conflicts(o, path, entry,
 +                                                     collisions, tree);
 +              *clean_merge &= (new_path != NULL);
 +      }
 +
 +      return new_path;
 +}
 +
 +static void apply_directory_rename_modifications(struct merge_options *o,
 +                                               struct diff_filepair *pair,
 +                                               char *new_path,
 +                                               struct rename *re,
 +                                               struct tree *tree,
 +                                               struct tree *o_tree,
 +                                               struct tree *a_tree,
 +                                               struct tree *b_tree,
 +                                               struct string_list *entries,
 +                                               int *clean)
 +{
 +      struct string_list_item *item;
 +      int stage = (tree == a_tree ? 2 : 3);
 +      int update_wd;
 +
 +      /*
 +       * In all cases where we can do directory rename detection,
 +       * unpack_trees() will have read pair->two->path into the
 +       * index and the working copy.  We need to remove it so that
 +       * we can instead place it at new_path.  It is guaranteed to
 +       * not be untracked (unpack_trees() would have errored out
 +       * saying the file would have been overwritten), but it might
 +       * be dirty, though.
 +       */
 +      update_wd = !was_dirty(o, pair->two->path);
 +      if (!update_wd)
 +              output(o, 1, _("Refusing to lose dirty file at %s"),
 +                     pair->two->path);
 +      remove_file(o, 1, pair->two->path, !update_wd);
 +
 +      /* Find or create a new re->dst_entry */
 +      item = string_list_lookup(entries, new_path);
 +      if (item) {
 +              /*
 +               * Since we're renaming on this side of history, and it's
 +               * due to a directory rename on the other side of history
 +               * (which we only allow when the directory in question no
 +               * longer exists on the other side of history), the
 +               * original entry for re->dst_entry is no longer
 +               * necessary...
 +               */
 +              re->dst_entry->processed = 1;
 +
 +              /*
 +               * ...because we'll be using this new one.
 +               */
 +              re->dst_entry = item->util;
 +      } else {
 +              /*
 +               * re->dst_entry is for the before-dir-rename path, and we
 +               * need it to hold information for the after-dir-rename
 +               * path.  Before creating a new entry, we need to mark the
 +               * old one as unnecessary (...unless it is shared by
 +               * src_entry, i.e. this didn't use to be a rename, in which
 +               * case we can just allow the normal processing to happen
 +               * for it).
 +               */
 +              if (pair->status == 'R')
 +                      re->dst_entry->processed = 1;
 +
 +              re->dst_entry = insert_stage_data(new_path,
 +                                                o_tree, a_tree, b_tree,
 +                                                entries);
 +              item = string_list_insert(entries, new_path);
 +              item->util = re->dst_entry;
 +      }
 +
 +      /*
 +       * Update the stage_data with the information about the path we are
 +       * moving into place.  That slot will be empty and available for us
 +       * to write to because of the collision checks in
 +       * handle_path_level_conflicts().  In other words,
 +       * re->dst_entry->stages[stage].oid will be the null_oid, so it's
 +       * open for us to write to.
 +       *
 +       * It may be tempting to actually update the index at this point as
 +       * well, using update_stages_for_stage_data(), but as per the big
 +       * "NOTE" in update_stages(), doing so will modify the current
 +       * in-memory index which will break calls to would_lose_untracked()
 +       * that we need to make.  Instead, we need to just make sure that
 +       * the various conflict_rename_*() functions update the index
 +       * explicitly rather than relying on unpack_trees() to have done it.
 +       */
 +      get_tree_entry(&tree->object.oid,
 +                     pair->two->path,
 +                     &re->dst_entry->stages[stage].oid,
 +                     &re->dst_entry->stages[stage].mode);
 +
 +      /* Update pair status */
 +      if (pair->status == 'A') {
 +              /*
 +               * Recording rename information for this add makes it look
 +               * like a rename/delete conflict.  Make sure we can
 +               * correctly handle this as an add that was moved to a new
 +               * directory instead of reporting a rename/delete conflict.
 +               */
 +              re->add_turned_into_rename = 1;
 +      }
 +      /*
 +       * We don't actually look at pair->status again, but it seems
 +       * pedagogically correct to adjust it.
 +       */
 +      pair->status = 'R';
 +
 +      /*
 +       * Finally, record the new location.
 +       */
 +      pair->two->path = new_path;
 +}
 +
 +/*
 + * Get information of all renames which occurred in 'pairs', making use of
 + * any implicit directory renames inferred from the other side of history.
 + * We need the three trees in the merge ('o_tree', 'a_tree' and 'b_tree')
 + * to be able to associate the correct cache entries with the rename
 + * information; tree is always equal to either a_tree or b_tree.
 + */
 +static struct string_list *get_renames(struct merge_options *o,
 +                                     struct diff_queue_struct *pairs,
 +                                     struct hashmap *dir_renames,
 +                                     struct hashmap *dir_rename_exclusions,
 +                                     struct tree *tree,
 +                                     struct tree *o_tree,
 +                                     struct tree *a_tree,
 +                                     struct tree *b_tree,
 +                                     struct string_list *entries,
 +                                     int *clean_merge)
 +{
 +      int i;
 +      struct hashmap collisions;
 +      struct hashmap_iter iter;
 +      struct collision_entry *e;
 +      struct string_list *renames;
 +
 +      compute_collisions(&collisions, dir_renames, pairs);
 +      renames = xcalloc(1, sizeof(struct string_list));
 +
 +      for (i = 0; i < pairs->nr; ++i) {
 +              struct string_list_item *item;
 +              struct rename *re;
 +              struct diff_filepair *pair = pairs->queue[i];
 +              char *new_path; /* non-NULL only with directory renames */
 +
 +              if (pair->status != 'A' && pair->status != 'R') {
 +                      diff_free_filepair(pair);
 +                      continue;
 +              }
 +              new_path = check_for_directory_rename(o, pair->two->path, tree,
 +                                                    dir_renames,
 +                                                    dir_rename_exclusions,
 +                                                    &collisions,
 +                                                    clean_merge);
 +              if (pair->status != 'R' && !new_path) {
 +                      diff_free_filepair(pair);
 +                      continue;
 +              }
 +
 +              re = xmalloc(sizeof(*re));
 +              re->processed = 0;
 +              re->add_turned_into_rename = 0;
 +              re->pair = pair;
 +              item = string_list_lookup(entries, re->pair->one->path);
 +              if (!item)
 +                      re->src_entry = insert_stage_data(re->pair->one->path,
 +                                      o_tree, a_tree, b_tree, entries);
 +              else
 +                      re->src_entry = item->util;
 +
 +              item = string_list_lookup(entries, re->pair->two->path);
 +              if (!item)
 +                      re->dst_entry = insert_stage_data(re->pair->two->path,
 +                                      o_tree, a_tree, b_tree, entries);
 +              else
 +                      re->dst_entry = item->util;
 +              item = string_list_insert(renames, pair->one->path);
 +              item->util = re;
 +              if (new_path)
 +                      apply_directory_rename_modifications(o, pair, new_path,
 +                                                           re, tree, o_tree,
 +                                                           a_tree, b_tree,
 +                                                           entries,
 +                                                           clean_merge);
 +      }
 +
 +      hashmap_iter_init(&collisions, &iter);
 +      while ((e = hashmap_iter_next(&iter))) {
 +              free(e->target_file);
 +              string_list_clear(&e->source_files, 0);
 +      }
 +      hashmap_free(&collisions, 1);
 +      return renames;
 +}
 +
 +static int process_renames(struct merge_options *o,
 +                         struct string_list *a_renames,
 +                         struct string_list *b_renames)
 +{
 +      int clean_merge = 1, i, j;
 +      struct string_list a_by_dst = STRING_LIST_INIT_NODUP;
 +      struct string_list b_by_dst = STRING_LIST_INIT_NODUP;
 +      const struct rename *sre;
 +
 +      for (i = 0; i < a_renames->nr; i++) {
 +              sre = a_renames->items[i].util;
 +              string_list_insert(&a_by_dst, sre->pair->two->path)->util
 +                      = (void *)sre;
 +      }
 +      for (i = 0; i < b_renames->nr; i++) {
 +              sre = b_renames->items[i].util;
 +              string_list_insert(&b_by_dst, sre->pair->two->path)->util
 +                      = (void *)sre;
 +      }
 +
 +      for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
 +              struct string_list *renames1, *renames2Dst;
 +              struct rename *ren1 = NULL, *ren2 = NULL;
 +              const char *branch1, *branch2;
 +              const char *ren1_src, *ren1_dst;
 +              struct string_list_item *lookup;
 +
 +              if (i >= a_renames->nr) {
 +                      ren2 = b_renames->items[j++].util;
 +              } else if (j >= b_renames->nr) {
 +                      ren1 = a_renames->items[i++].util;
 +              } else {
 +                      int compare = strcmp(a_renames->items[i].string,
 +                                           b_renames->items[j].string);
                        if (compare <= 0)
                                ren1 = a_renames->items[i++].util;
                        if (compare >= 0)
                        const char *ren2_dst = ren2->pair->two->path;
                        enum rename_type rename_type;
                        if (strcmp(ren1_src, ren2_src) != 0)
 -                              die("BUG: ren1_src != ren2_src");
 +                              BUG("ren1_src != ren2_src");
                        ren2->dst_entry->processed = 1;
                        ren2->processed = 1;
                        if (strcmp(ren1_dst, ren2_dst) != 0) {
                        ren2 = lookup->util;
                        ren2_dst = ren2->pair->two->path;
                        if (strcmp(ren1_dst, ren2_dst) != 0)
 -                              die("BUG: ren1_dst != ren2_dst");
 +                              BUG("ren1_dst != ren2_dst");
  
                        clean_merge = 0;
                        ren2->processed = 1;
                         * add-source case).
                         */
                        remove_file(o, 1, ren1_src,
 -                                  renamed_stage == 2 || !was_tracked(ren1_src));
 +                                  renamed_stage == 2 || !was_tracked(o, ren1_src));
  
                        oidcpy(&src_other.oid,
                               &ren1->src_entry->stages[other_stage].oid);
                        dst_other.mode = ren1->dst_entry->stages[other_stage].mode;
                        try_merge = 0;
  
 -                      if (oid_eq(&src_other.oid, &null_oid)) {
 +                      if (oid_eq(&src_other.oid, &null_oid) &&
 +                          ren1->add_turned_into_rename) {
 +                              setup_rename_conflict_info(RENAME_DIR,
 +                                                         ren1->pair,
 +                                                         NULL,
 +                                                         branch1,
 +                                                         branch2,
 +                                                         ren1->dst_entry,
 +                                                         NULL,
 +                                                         o,
 +                                                         NULL,
 +                                                         NULL);
 +                      } else if (oid_eq(&src_other.oid, &null_oid)) {
                                setup_rename_conflict_info(RENAME_DELETE,
                                                           ren1->pair,
                                                           NULL,
@@@ -2801,105 -1646,6 +2802,105 @@@ cleanup_and_return
        return clean_merge;
  }
  
 +struct rename_info {
 +      struct string_list *head_renames;
 +      struct string_list *merge_renames;
 +};
 +
 +static void initial_cleanup_rename(struct diff_queue_struct *pairs,
 +                                 struct hashmap *dir_renames)
 +{
 +      struct hashmap_iter iter;
 +      struct dir_rename_entry *e;
 +
 +      hashmap_iter_init(dir_renames, &iter);
 +      while ((e = hashmap_iter_next(&iter))) {
 +              free(e->dir);
 +              strbuf_release(&e->new_dir);
 +              /* possible_new_dirs already cleared in get_directory_renames */
 +      }
 +      hashmap_free(dir_renames, 1);
 +      free(dir_renames);
 +
 +      free(pairs->queue);
 +      free(pairs);
 +}
 +
 +static int handle_renames(struct merge_options *o,
 +                        struct tree *common,
 +                        struct tree *head,
 +                        struct tree *merge,
 +                        struct string_list *entries,
 +                        struct rename_info *ri)
 +{
 +      struct diff_queue_struct *head_pairs, *merge_pairs;
 +      struct hashmap *dir_re_head, *dir_re_merge;
 +      int clean = 1;
 +
 +      ri->head_renames = NULL;
 +      ri->merge_renames = NULL;
 +
 +      if (!merge_detect_rename(o))
 +              return 1;
 +
 +      head_pairs = get_diffpairs(o, common, head);
 +      merge_pairs = get_diffpairs(o, common, merge);
 +
 +      dir_re_head = get_directory_renames(head_pairs, head);
 +      dir_re_merge = get_directory_renames(merge_pairs, merge);
 +
 +      handle_directory_level_conflicts(o,
 +                                       dir_re_head, head,
 +                                       dir_re_merge, merge);
 +
 +      ri->head_renames  = get_renames(o, head_pairs,
 +                                      dir_re_merge, dir_re_head, head,
 +                                      common, head, merge, entries,
 +                                      &clean);
 +      if (clean < 0)
 +              goto cleanup;
 +      ri->merge_renames = get_renames(o, merge_pairs,
 +                                      dir_re_head, dir_re_merge, merge,
 +                                      common, head, merge, entries,
 +                                      &clean);
 +      if (clean < 0)
 +              goto cleanup;
 +      clean &= process_renames(o, ri->head_renames, ri->merge_renames);
 +
 +cleanup:
 +      /*
 +       * Some cleanup is deferred until cleanup_renames() because the
 +       * data structures are still needed and referenced in
 +       * process_entry().  But there are a few things we can free now.
 +       */
 +      initial_cleanup_rename(head_pairs, dir_re_head);
 +      initial_cleanup_rename(merge_pairs, dir_re_merge);
 +
 +      return clean;
 +}
 +
 +static void final_cleanup_rename(struct string_list *rename)
 +{
 +      const struct rename *re;
 +      int i;
 +
 +      if (rename == NULL)
 +              return;
 +
 +      for (i = 0; i < rename->nr; i++) {
 +              re = rename->items[i].util;
 +              diff_free_filepair(re->pair);
 +      }
 +      string_list_clear(rename, 1);
 +      free(rename);
 +}
 +
 +static void final_cleanup_renames(struct rename_info *re_info)
 +{
 +      final_cleanup_rename(re_info->head_renames);
 +      final_cleanup_rename(re_info->merge_renames);
 +}
 +
  static struct object_id *stage_oid(const struct object_id *oid, unsigned mode)
  {
        return (is_null_oid(oid) || mode == 0) ? NULL: (struct object_id *)oid;
@@@ -2990,7 -1736,6 +2991,7 @@@ static int handle_modify_delete(struct 
  
  static int merge_content(struct merge_options *o,
                         const char *path,
 +                       int is_dirty,
                         struct object_id *o_oid, int o_mode,
                         struct object_id *a_oid, int a_mode,
                         struct object_id *b_oid, int b_mode,
                               S_ISGITLINK(pair1->two->mode)))
                        df_conflict_remains = 1;
        }
 -      if (merge_file_special_markers(o, &one, &a, &b,
 +      if (merge_file_special_markers(o, &one, &a, &b, path,
                                       o->branch1, path1,
                                       o->branch2, path2, &mfi))
                return -1;
  
 -      if (mfi.clean && !df_conflict_remains &&
 -          oid_eq(&mfi.oid, a_oid) && mfi.mode == a_mode) {
 -              int path_renamed_outside_HEAD;
 +      /*
 +       * We can skip updating the working tree file iff:
 +       *   a) The merge is clean
 +       *   b) The merge matches what was in HEAD (content, mode, pathname)
 +       *   c) The target path is usable (i.e. not involved in D/F conflict)
 +       */
 +      if (mfi.clean &&
 +          was_tracked_and_matches(o, path, &mfi.oid, mfi.mode) &&
 +          !df_conflict_remains) {
                output(o, 3, _("Skipped %s (merged same as existing)"), path);
 -              /*
 -               * The content merge resulted in the same file contents we
 -               * already had.  We can return early if those file contents
 -               * are recorded at the correct path (which may not be true
 -               * if the merge involves a rename).
 -               */
 -              path_renamed_outside_HEAD = !path2 || !strcmp(path, path2);
 -              if (!path_renamed_outside_HEAD) {
 -                      add_cacheinfo(o, mfi.mode, &mfi.oid, path,
 -                                    0, (!o->call_depth), 0);
 -                      return mfi.clean;
 -              }
 -      } else
 -              output(o, 2, _("Auto-merging %s"), path);
 +              if (add_cacheinfo(o, mfi.mode, &mfi.oid, path,
 +                                0, (!o->call_depth && !is_dirty), 0))
 +                      return -1;
 +              return mfi.clean;
 +      }
  
        if (!mfi.clean) {
                if (S_ISGITLINK(mfi.mode))
                                return -1;
        }
  
 -      if (df_conflict_remains) {
 +      if (df_conflict_remains || is_dirty) {
                char *new_path;
                if (o->call_depth) {
                        remove_file_from_cache(path);
                                if (update_stages(o, path, &one, &a, &b))
                                        return -1;
                        } else {
 -                              int file_from_stage2 = was_tracked(path);
 +                              int file_from_stage2 = was_tracked(o, path);
                                struct diff_filespec merged;
                                oidcpy(&merged.oid, &mfi.oid);
                                merged.mode = mfi.mode;
  
                }
                new_path = unique_path(o, path, rename_conflict_info->branch1);
 +              if (is_dirty) {
 +                      output(o, 1, _("Refusing to lose dirty file at %s"),
 +                             path);
 +              }
                output(o, 1, _("Adding as %s instead"), new_path);
                if (update_file(o, 0, &mfi.oid, mfi.mode, new_path)) {
                        free(new_path);
                mfi.clean = 0;
        } else if (update_file(o, mfi.clean, &mfi.oid, mfi.mode, path))
                return -1;
 -      return mfi.clean;
 +      return !is_dirty && mfi.clean;
 +}
 +
 +static int conflict_rename_normal(struct merge_options *o,
 +                                const char *path,
 +                                struct object_id *o_oid, unsigned int o_mode,
 +                                struct object_id *a_oid, unsigned int a_mode,
 +                                struct object_id *b_oid, unsigned int b_mode,
 +                                struct rename_conflict_info *ci)
 +{
 +      /* Merge the content and write it out */
 +      return merge_content(o, path, was_dirty(o, path),
 +                           o_oid, o_mode, a_oid, a_mode, b_oid, b_mode,
 +                           ci);
  }
  
  /* Per entry merge function */
@@@ -3132,20 -1863,9 +3133,20 @@@ static int process_entry(struct merge_o
                switch (conflict_info->rename_type) {
                case RENAME_NORMAL:
                case RENAME_ONE_FILE_TO_ONE:
 -                      clean_merge = merge_content(o, path,
 -                                                  o_oid, o_mode, a_oid, a_mode, b_oid, b_mode,
 -                                                  conflict_info);
 +                      clean_merge = conflict_rename_normal(o,
 +                                                           path,
 +                                                           o_oid, o_mode,
 +                                                           a_oid, a_mode,
 +                                                           b_oid, b_mode,
 +                                                           conflict_info);
 +                      break;
 +              case RENAME_DIR:
 +                      clean_merge = 1;
 +                      if (conflict_rename_dir(o,
 +                                              conflict_info->pair1,
 +                                              conflict_info->branch1,
 +                                              conflict_info->branch2))
 +                              clean_merge = -1;
                        break;
                case RENAME_DELETE:
                        clean_merge = 0;
        } else if (a_oid && b_oid) {
                /* Case C: Added in both (check for same permissions) and */
                /* case D: Modified in both, but differently. */
 -              clean_merge = merge_content(o, path,
 +              int is_dirty = 0; /* unpack_trees would have bailed if dirty */
 +              clean_merge = merge_content(o, path, is_dirty,
                                            o_oid, o_mode, a_oid, a_mode, b_oid, b_mode,
                                            NULL);
        } else if (!o_oid && !a_oid && !b_oid) {
                 */
                remove_file(o, 1, path, !a_mode);
        } else
 -              die("BUG: fatal merge failure, shouldn't happen.");
 +              BUG("fatal merge failure, shouldn't happen.");
  
        return clean_merge;
  }
@@@ -3275,20 -1994,18 +3276,20 @@@ int merge_trees(struct merge_options *o
                return 1;
        }
  
 -      code = git_merge_trees(o->call_depth, common, head, merge);
 +      code = unpack_trees_start(o, common, head, merge);
  
        if (code != 0) {
                if (show(o, 4) || o->call_depth)
                        err(o, _("merging of trees %s and %s failed"),
                            oid_to_hex(&head->object.oid),
                            oid_to_hex(&merge->object.oid));
 +              unpack_trees_finish(o);
                return -1;
        }
  
        if (unmerged_cache()) {
 -              struct string_list *entries, *re_head, *re_merge;
 +              struct string_list *entries;
 +              struct rename_info re_info;
                int i;
                /*
                 * Only need the hashmap while processing entries, so
                get_files_dirs(o, merge);
  
                entries = get_unmerged();
 -              re_head  = get_renames(o, head, common, head, merge, entries);
 -              re_merge = get_renames(o, merge, common, head, merge, entries);
 -              clean = process_renames(o, re_head, re_merge);
 +              clean = handle_renames(o, common, head, merge, entries,
 +                                     &re_info);
                record_df_conflict_files(o, entries);
                if (clean < 0)
                        goto cleanup;
                for (i = 0; i < entries->nr; i++) {
                        struct stage_data *e = entries->items[i].util;
                        if (!e->processed)
 -                              die("BUG: unprocessed path??? %s",
 +                              BUG("unprocessed path??? %s",
                                    entries->items[i].string);
                }
  
  cleanup:
 -              string_list_clear(re_merge, 0);
 -              string_list_clear(re_head, 0);
 +              final_cleanup_renames(&re_info);
 +
                string_list_clear(entries, 1);
 +              free(entries);
  
                hashmap_free(&o->current_file_dir_set, 1);
  
 -              free(re_merge);
 -              free(re_head);
 -              free(entries);
 -
 -              if (clean < 0)
 +              if (clean < 0) {
 +                      unpack_trees_finish(o);
                        return clean;
 +              }
        }
        else
                clean = 1;
  
 +      unpack_trees_finish(o);
 +
        if (o->call_depth && !(*result = write_tree_from_memory(o)))
                return -1;
  
@@@ -3438,8 -2155,7 +3439,8 @@@ int merge_recursive(struct merge_option
                read_cache();
  
        o->ancestor = "merged common ancestors";
 -      clean = merge_trees(o, h1->tree, h2->tree, merged_common_ancestors->tree,
 +      clean = merge_trees(o, get_commit_tree(h1), get_commit_tree(h2),
 +                          get_commit_tree(merged_common_ancestors),
                            &mrtree);
        if (clean < 0) {
                flush_output(o);
@@@ -3517,18 -2233,9 +3518,18 @@@ int merge_recursive_generic(struct merg
  
  static void merge_recursive_config(struct merge_options *o)
  {
 +      char *value = NULL;
        git_config_get_int("merge.verbosity", &o->verbosity);
        git_config_get_int("diff.renamelimit", &o->diff_rename_limit);
        git_config_get_int("merge.renamelimit", &o->merge_rename_limit);
 +      if (!git_config_get_string("diff.renames", &value)) {
 +              o->diff_detect_rename = git_config_rename("diff.renames", value);
 +              free(value);
 +      }
 +      if (!git_config_get_string("merge.renames", &value)) {
 +              o->merge_detect_rename = git_config_rename("merge.renames", value);
 +              free(value);
 +      }
        git_config(git_xmerge_config, NULL);
  }
  
@@@ -3541,8 -2248,7 +3542,8 @@@ void init_merge_options(struct merge_op
        o->diff_rename_limit = -1;
        o->merge_rename_limit = -1;
        o->renormalize = 0;
 -      o->detect_rename = 1;
 +      o->diff_detect_rename = -1;
 +      o->merge_detect_rename = -1;
        merge_recursive_config(o);
        merge_verbosity = getenv("GIT_MERGE_VERBOSITY");
        if (merge_verbosity)
@@@ -3593,16 -2299,16 +3594,16 @@@ int parse_merge_opt(struct merge_option
        else if (!strcmp(s, "no-renormalize"))
                o->renormalize = 0;
        else if (!strcmp(s, "no-renames"))
 -              o->detect_rename = 0;
 +              o->merge_detect_rename = 0;
        else if (!strcmp(s, "find-renames")) {
 -              o->detect_rename = 1;
 +              o->merge_detect_rename = 1;
                o->rename_score = 0;
        }
        else if (skip_prefix(s, "find-renames=", &arg) ||
                 skip_prefix(s, "rename-threshold=", &arg)) {
                if ((o->rename_score = parse_rename_score(&arg)) == -1 || *arg != 0)
                        return -1;
 -              o->detect_rename = 1;
 +              o->merge_detect_rename = 1;
        }
        else
                return -1;
diff --combined object.c
index d33e2a5cc84623451a0cc02c0345233675b0340d,8e29f63bf2325327027edc1ffd25e89b53309bcf..10d167825ea8d8048640001f28750dd0834aa169
+++ b/object.c
@@@ -5,20 -5,18 +5,18 @@@
  #include "tree.h"
  #include "commit.h"
  #include "tag.h"
+ #include "alloc.h"
  #include "object-store.h"
  #include "packfile.h"
  
- static struct object **obj_hash;
- static int nr_objs, obj_hash_size;
  unsigned int get_max_object_index(void)
  {
-       return obj_hash_size;
+       return the_repository->parsed_objects->obj_hash_size;
  }
  
  struct object *get_indexed_object(unsigned int idx)
  {
-       return obj_hash[idx];
+       return the_repository->parsed_objects->obj_hash[idx];
  }
  
  static const char *object_type_strings[] = {
@@@ -90,15 -88,16 +88,16 @@@ struct object *lookup_object(const unsi
        unsigned int i, first;
        struct object *obj;
  
-       if (!obj_hash)
+       if (!the_repository->parsed_objects->obj_hash)
                return NULL;
  
-       first = i = hash_obj(sha1, obj_hash_size);
-       while ((obj = obj_hash[i]) != NULL) {
+       first = i = hash_obj(sha1,
+                            the_repository->parsed_objects->obj_hash_size);
+       while ((obj = the_repository->parsed_objects->obj_hash[i]) != NULL) {
                if (!hashcmp(sha1, obj->oid.hash))
                        break;
                i++;
-               if (i == obj_hash_size)
+               if (i == the_repository->parsed_objects->obj_hash_size)
                        i = 0;
        }
        if (obj && i != first) {
                 * that we do not need to walk the hash table the next
                 * time we look for it.
                 */
-               SWAP(obj_hash[i], obj_hash[first]);
+               SWAP(the_repository->parsed_objects->obj_hash[i],
+                    the_repository->parsed_objects->obj_hash[first]);
        }
        return obj;
  }
   * power of 2 (but at least 32).  Copy the existing values to the new
   * hash map.
   */
- static void grow_object_hash(void)
+ static void grow_object_hash(struct repository *r)
  {
        int i;
        /*
         * Note that this size must always be power-of-2 to match hash_obj
         * above.
         */
-       int new_hash_size = obj_hash_size < 32 ? 32 : 2 * obj_hash_size;
+       int new_hash_size = r->parsed_objects->obj_hash_size < 32 ? 32 : 2 * r->parsed_objects->obj_hash_size;
        struct object **new_hash;
  
        new_hash = xcalloc(new_hash_size, sizeof(struct object *));
-       for (i = 0; i < obj_hash_size; i++) {
-               struct object *obj = obj_hash[i];
+       for (i = 0; i < r->parsed_objects->obj_hash_size; i++) {
+               struct object *obj = r->parsed_objects->obj_hash[i];
                if (!obj)
                        continue;
                insert_obj_hash(obj, new_hash, new_hash_size);
        }
-       free(obj_hash);
-       obj_hash = new_hash;
-       obj_hash_size = new_hash_size;
+       free(r->parsed_objects->obj_hash);
+       r->parsed_objects->obj_hash = new_hash;
+       r->parsed_objects->obj_hash_size = new_hash_size;
  }
  
- void *create_object(const unsigned char *sha1, void *o)
+ void *create_object(struct repository *r, const unsigned char *sha1, void *o)
  {
        struct object *obj = o;
  
        obj->flags = 0;
        hashcpy(obj->oid.hash, sha1);
  
-       if (obj_hash_size - 1 <= nr_objs * 2)
-               grow_object_hash();
+       if (r->parsed_objects->obj_hash_size - 1 <= r->parsed_objects->nr_objs * 2)
+               grow_object_hash(r);
  
-       insert_obj_hash(obj, obj_hash, obj_hash_size);
-       nr_objs++;
+       insert_obj_hash(obj, r->parsed_objects->obj_hash,
+                       r->parsed_objects->obj_hash_size);
+       r->parsed_objects->nr_objs++;
        return obj;
  }
  
@@@ -161,7 -163,7 +163,7 @@@ void *object_as_type(struct object *obj
                return obj;
        else if (obj->type == OBJ_NONE) {
                if (type == OBJ_COMMIT)
-                       ((struct commit *)obj)->index = alloc_commit_index();
+                       ((struct commit *)obj)->index = alloc_commit_index(the_repository);
                obj->type = type;
                return obj;
        }
@@@ -178,7 -180,8 +180,8 @@@ struct object *lookup_unknown_object(co
  {
        struct object *obj = lookup_object(sha1);
        if (!obj)
-               obj = create_object(sha1, alloc_object_node());
+               obj = create_object(the_repository, sha1,
+                                   alloc_object_node(the_repository));
        return obj;
  }
  
@@@ -210,7 -213,7 +213,7 @@@ struct object *parse_object_buffer(cons
        } else if (type == OBJ_COMMIT) {
                struct commit *commit = lookup_commit(oid);
                if (commit) {
 -                      if (parse_commit_buffer(commit, buffer, size))
 +                      if (parse_commit_buffer(commit, buffer, size, 1))
                                return NULL;
                        if (!get_cached_commit_buffer(commit, NULL)) {
                                set_commit_buffer(commit, buffer, size);
@@@ -431,8 -434,8 +434,8 @@@ void clear_object_flags(unsigned flags
  {
        int i;
  
-       for (i=0; i < obj_hash_size; i++) {
-               struct object *obj = obj_hash[i];
+       for (i=0; i < the_repository->parsed_objects->obj_hash_size; i++) {
+               struct object *obj = the_repository->parsed_objects->obj_hash[i];
                if (obj)
                        obj->flags &= ~flags;
        }
@@@ -442,13 -445,27 +445,27 @@@ void clear_commit_marks_all(unsigned in
  {
        int i;
  
-       for (i = 0; i < obj_hash_size; i++) {
-               struct object *obj = obj_hash[i];
+       for (i = 0; i < the_repository->parsed_objects->obj_hash_size; i++) {
+               struct object *obj = the_repository->parsed_objects->obj_hash[i];
                if (obj && obj->type == OBJ_COMMIT)
                        obj->flags &= ~flags;
        }
  }
  
+ struct parsed_object_pool *parsed_object_pool_new(void)
+ {
+       struct parsed_object_pool *o = xmalloc(sizeof(*o));
+       memset(o, 0, sizeof(*o));
+       o->blob_state = allocate_alloc_state();
+       o->tree_state = allocate_alloc_state();
+       o->commit_state = allocate_alloc_state();
+       o->tag_state = allocate_alloc_state();
+       o->object_state = allocate_alloc_state();
+       return o;
+ }
  struct raw_object_store *raw_object_store_new(void)
  {
        struct raw_object_store *o = xmalloc(sizeof(*o));
@@@ -481,9 -498,6 +498,9 @@@ void raw_object_store_clear(struct raw_
        FREE_AND_NULL(o->objectdir);
        FREE_AND_NULL(o->alternate_db);
  
 +      oidmap_free(o->replace_map, 1);
 +      FREE_AND_NULL(o->replace_map);
 +
        free_alt_odbs(o);
        o->alt_odb_tail = NULL;
  
        close_all_packs(o);
        o->packed_git = NULL;
  }
+ void parsed_object_pool_clear(struct parsed_object_pool *o)
+ {
+       /*
+        * As objects are allocated in slabs (see alloc.c), we do
+        * not need to free each object, but each slab instead.
+        *
+        * Before doing so, we need to free any additional memory
+        * the objects may hold.
+        */
+       unsigned i;
+       for (i = 0; i < o->obj_hash_size; i++) {
+               struct object *obj = o->obj_hash[i];
+               if (!obj)
+                       continue;
+               if (obj->type == OBJ_TREE)
+                       free_tree_buffer((struct tree*)obj);
+               else if (obj->type == OBJ_COMMIT)
+                       release_commit_memory((struct commit*)obj);
+               else if (obj->type == OBJ_TAG)
+                       release_tag_memory((struct tag*)obj);
+       }
+       FREE_AND_NULL(o->obj_hash);
+       o->obj_hash_size = 0;
+       clear_alloc_state(o->blob_state);
+       clear_alloc_state(o->tree_state);
+       clear_alloc_state(o->commit_state);
+       clear_alloc_state(o->tag_state);
+       clear_alloc_state(o->object_state);
+       FREE_AND_NULL(o->blob_state);
+       FREE_AND_NULL(o->tree_state);
+       FREE_AND_NULL(o->commit_state);
+       FREE_AND_NULL(o->tag_state);
+       FREE_AND_NULL(o->object_state);
+ }
diff --combined object.h
index acc560b24e4ba57d820b61896ba07d4d3f640f33,7916edb4edf0158d65dd194aeba85741b33a3776..47d1b4902263c4059d8b27e17c7d7fc042dc6771
+++ b/object.h
@@@ -1,6 -1,22 +1,22 @@@
  #ifndef OBJECT_H
  #define OBJECT_H
  
+ struct parsed_object_pool {
+       struct object **obj_hash;
+       int nr_objs, obj_hash_size;
+       /* TODO: migrate alloc_states to mem-pool? */
+       struct alloc_state *blob_state;
+       struct alloc_state *tree_state;
+       struct alloc_state *commit_state;
+       struct alloc_state *tag_state;
+       struct alloc_state *object_state;
+       unsigned commit_count;
+ };
+ struct parsed_object_pool *parsed_object_pool_new(void);
+ void parsed_object_pool_clear(struct parsed_object_pool *o);
  struct object_list {
        struct object *item;
        struct object_list *next;
@@@ -25,6 -41,7 +41,6 @@@ struct object_array 
  
  #define OBJECT_ARRAY_INIT { 0, 0, NULL }
  
 -#define TYPE_BITS   3
  /*
   * object flag allocation:
   * revision.h:               0---------10                                26
   * bundle.c:                                        16
   * http-push.c:                                     16-----19
   * commit.c:                                        16-----19
 - * sha1_name.c:                                              20
 + * sha1-name.c:                                              20
   * list-objects-filter.c:                                      21
   * builtin/fsck.c:           0--3
   * builtin/index-pack.c:                                     2021
   * builtin/pack-objects.c:                                   20
   * builtin/reflog.c:                   10--12
 + * builtin/show-branch.c:    0-------------------------------------------26
   * builtin/unpack-objects.c:                                 2021
   */
  #define FLAG_BITS  27
@@@ -85,7 -101,7 +101,7 @@@ extern struct object *get_indexed_objec
   */
  struct object *lookup_object(const unsigned char *sha1);
  
- extern void *create_object(const unsigned char *sha1, void *obj);
+ extern void *create_object(struct repository *r, const unsigned char *sha1, void *obj);
  
  void *object_as_type(struct object *obj, enum object_type type, int quiet);
  
diff --combined repository.c
index 02fe884603df56ea0996121152b7640afb56a48f,c23404677eb0bcd16564bdb93c438894ad37eca8..5dd148671811b383a64b8f3adab87804cea9db08
@@@ -2,6 -2,7 +2,7 @@@
  #include "repository.h"
  #include "object-store.h"
  #include "config.h"
+ #include "object.h"
  #include "submodule-config.h"
  
  /* The main repository */
@@@ -14,6 -15,8 +15,8 @@@ void initialize_the_repository(void
  
        the_repo.index = &the_index;
        the_repo.objects = raw_object_store_new();
+       the_repo.parsed_objects = parsed_object_pool_new();
        repo_set_hash_algo(&the_repo, GIT_HASH_SHA1);
  }
  
@@@ -135,14 -138,15 +138,15 @@@ static int read_and_verify_repository_f
   * Initialize 'repo' based on the provided 'gitdir'.
   * Return 0 upon success and a non-zero value upon failure.
   */
 -static int repo_init(struct repository *repo,
 -                   const char *gitdir,
 -                   const char *worktree)
 +int repo_init(struct repository *repo,
 +            const char *gitdir,
 +            const char *worktree)
  {
        struct repository_format format;
        memset(repo, 0, sizeof(*repo));
  
        repo->objects = raw_object_store_new();
+       repo->parsed_objects = parsed_object_pool_new();
  
        if (repo_init_gitdir(repo, gitdir))
                goto error;
@@@ -176,7 -180,7 +180,7 @@@ int repo_submodule_init(struct reposito
        struct strbuf worktree = STRBUF_INIT;
        int ret = 0;
  
 -      sub = submodule_from_cache(superproject, &null_oid, path);
 +      sub = submodule_from_path(superproject, &null_oid, path);
        if (!sub) {
                ret = -1;
                goto out;
@@@ -226,6 -230,9 +230,9 @@@ void repo_clear(struct repository *repo
        raw_object_store_clear(repo->objects);
        FREE_AND_NULL(repo->objects);
  
+       parsed_object_pool_clear(repo->parsed_objects);
+       FREE_AND_NULL(repo->parsed_objects);
        if (repo->config) {
                git_configset_clear(repo->config);
                FREE_AND_NULL(repo->config);
  
        if (repo->index) {
                discard_index(repo->index);
 -              FREE_AND_NULL(repo->index);
 +              if (repo->index != &the_index)
 +                      FREE_AND_NULL(repo->index);
        }
  }
  
diff --combined repository.h
index f2646f0c52aa83f6da8950cfd96c4308498cf417,6d199819905f2a9f8334e496f2caf35a3546420c..dba3ddbfdd2d48068d60100425d1a22025cd25b0
@@@ -26,6 -26,15 +26,15 @@@ struct repository 
         */
        struct raw_object_store *objects;
  
+       /*
+        * All objects in this repository that have been parsed. This structure
+        * owns all objects it references, so users of "struct object *"
+        * generally do not need to free them; instead, when a repository is no
+        * longer used, call parsed_object_pool_clear() on this structure, which
+        * is called by the repositories repo_clear on its desconstruction.
+        */
+       struct parsed_object_pool *parsed_objects;
        /* The store in which the refs are held. */
        struct ref_store *refs;
  
@@@ -100,9 -109,6 +109,9 @@@ extern void repo_set_gitdir(struct repo
  extern void repo_set_worktree(struct repository *repo, const char *path);
  extern void repo_set_hash_algo(struct repository *repo, int algo);
  extern void initialize_the_repository(void);
 +extern int repo_init(struct repository *r,
 +                   const char *gitdir,
 +                   const char *worktree);
  extern int repo_submodule_init(struct repository *submodule,
                               struct repository *superproject,
                               const char *path);
diff --combined tree.c
index 244eb5e665e931a6b735366d74b5ed2bcbce4c9b,8f8ef3189af9f0cbf1f4d2f1de9427850e78fd58..2c9c49725ca0eb311a4e82081a6748db7c8e1fcd
--- 1/tree.c
--- 2/tree.c
+++ b/tree.c
@@@ -5,6 -5,7 +5,7 @@@
  #include "blob.h"
  #include "commit.h"
  #include "tag.h"
+ #include "alloc.h"
  #include "tree-walk.h"
  
  const char *tree_type = "tree";
@@@ -109,7 -110,7 +110,7 @@@ static int read_tree_1(struct tree *tre
                                    oid_to_hex(entry.oid),
                                    base->buf, entry.path);
  
 -                      oidcpy(&oid, &commit->tree->object.oid);
 +                      oidcpy(&oid, get_commit_tree_oid(commit));
                }
                else
                        continue;
@@@ -196,7 -197,8 +197,8 @@@ struct tree *lookup_tree(const struct o
  {
        struct object *obj = lookup_object(oid->hash);
        if (!obj)
-               return create_object(oid->hash, alloc_tree_node());
+               return create_object(the_repository, oid->hash,
+                                    alloc_tree_node(the_repository));
        return object_as_type(obj, OBJ_TREE, 0);
  }
  
@@@ -248,7 -250,7 +250,7 @@@ struct tree *parse_tree_indirect(const 
                if (obj->type == OBJ_TREE)
                        return (struct tree *) obj;
                else if (obj->type == OBJ_COMMIT)
 -                      obj = &(((struct commit *) obj)->tree->object);
 +                      obj = &(get_commit_tree(((struct commit *)obj))->object);
                else if (obj->type == OBJ_TAG)
                        obj = ((struct tag *) obj)->tagged;
                else