Add explanation of the profile feedback build to the README

diff --git a/Makefile b/Makefile
index f52d84b89f25c04685be163077af5f1a3abf06e4..2d7f6ba122ec93e8006937a94340d01c6816546e 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -24,6 +24,12 @@ all::
 # Define NO_OPENSSL environment variable if you do not have OpenSSL.
 # This also implies BLK_SHA1.
 #
+# Define USE_LIBPCRE if you have and want to use libpcre. git-grep will be
+# able to use Perl-compatible regular expressions.
+#
+# Define LIBPCREDIR=/foo/bar if your libpcre header and library files are in
+# /foo/bar/include and /foo/bar/lib directories.
+#
 # Define NO_CURL if you do not have libcurl installed.  git-http-pull and
 # git-http-push are not built, and you cannot use http:// and https://
 # transports.
@@ -147,6 +153,9 @@ all::
 # that tells runtime paths to dynamic libraries;
 # "-Wl,-rpath=/path/lib" is used instead.
 #
+# Define NO_NORETURN if using buggy versions of gcc 4.6+ and profile feedback,
+# as the compiler can crash (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49299)
+#
 # Define USE_NSEC below if you want git to care about sub-second file mtimes
 # and ctimes. Note that you need recent glibc (at least 2.2.4) for this, and
 # it will BREAK YOUR LOCAL DIFFS! show-diff and anything using it will likely
@@ -545,6 +554,7 @@ LIB_H += rerere.h
 LIB_H += resolve-undo.h
 LIB_H += revision.h
 LIB_H += run-command.h
+LIB_H += sha1-array.h
 LIB_H += sha1-lookup.h
 LIB_H += sideband.h
 LIB_H += sigchain.h
@@ -647,6 +657,7 @@ LIB_OBJS += revision.o
 LIB_OBJS += run-command.o
 LIB_OBJS += server-info.o
 LIB_OBJS += setup.o
+LIB_OBJS += sha1-array.o
 LIB_OBJS += sha1-lookup.o
 LIB_OBJS += sha1_file.o
 LIB_OBJS += sha1_name.o
@@ -1256,6 +1267,15 @@ ifdef NO_LIBGEN_H
        COMPAT_OBJS += compat/basename.o
 endif
 
+ifdef USE_LIBPCRE
+       BASIC_CFLAGS += -DUSE_LIBPCRE
+       ifdef LIBPCREDIR
+               BASIC_CFLAGS += -I$(LIBPCREDIR)/include
+               EXTLIBS += -L$(LIBPCREDIR)/$(lib) $(CC_LD_DYNPATH)$(LIBPCREDIR)/$(lib)
+       endif
+       EXTLIBS += -lpcre
+endif
+
 ifdef NO_CURL
        BASIC_CFLAGS += -DNO_CURL
        REMOTE_CURL_PRIMARY =
@@ -1357,6 +1377,9 @@ endif
 ifdef USE_ST_TIMESPEC
        BASIC_CFLAGS += -DUSE_ST_TIMESPEC
 endif
+ifdef NO_NORETURN
+       BASIC_CFLAGS += -DNO_NORETURN
+endif
 ifdef NO_NSEC
        BASIC_CFLAGS += -DNO_NSEC
 endif
@@ -2087,6 +2110,7 @@ GIT-BUILD-OPTIONS: FORCE
        @echo PYTHON_PATH=\''$(subst ','\'',$(PYTHON_PATH_SQ))'\' >>$@
        @echo TAR=\''$(subst ','\'',$(subst ','\'',$(TAR)))'\' >>$@
        @echo NO_CURL=\''$(subst ','\'',$(subst ','\'',$(NO_CURL)))'\' >>$@
+       @echo USE_LIBPCRE=\''$(subst ','\'',$(subst ','\'',$(USE_LIBPCRE)))'\' >>$@
        @echo NO_PERL=\''$(subst ','\'',$(subst ','\'',$(NO_PERL)))'\' >>$@
        @echo NO_PYTHON=\''$(subst ','\'',$(subst ','\'',$(NO_PYTHON)))'\' >>$@
 ifdef GIT_TEST_CMP
@@ -2468,3 +2492,19 @@ cover_db: coverage-report
 
 cover_db_html: cover_db
        cover -report html -outputdir cover_db_html cover_db
+
+### profile feedback build
+#
+.PHONY: profile-all profile-clean
+
+PROFILE_GEN_CFLAGS := $(CFLAGS) -fprofile-generate -DNO_NORETURN=1
+PROFILE_USE_CFLAGS := $(CFLAGS) -fprofile-use -fprofile-correction -DNO_NORETURN=1
+
+profile-clean:
+       $(RM) $(addsuffix *.gcda,$(object_dirs))
+       $(RM) $(addsuffix *.gcno,$(object_dirs))
+
+profile-all: profile-clean
+       $(MAKE) CFLAGS="$(PROFILE_GEN_CFLAGS)" all
+       $(MAKE) CFLAGS="$(PROFILE_GEN_CFLAGS)" -j1 test
+       $(MAKE) CFLAGS="$(PROFILE_USE_CFLAGS)" all