xdiff/xhistogram: rework handling of recursed results

Previously we were over-complicating matters by trying to combine the
recursed results. Now, terminate immediately if a recursive call failed
and return its result.

Signed-off-by: Tay Ray Chuan <rctay89@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/xdiff/xhistogram.c b/xdiff/xhistogram.c
index 391333a1a44892547be93d71cad59a7505e86e78..4cfafa1b3ae5669a0f2844ffb60a044c96f34db6 100644 (file)
--- a/xdiff/xhistogram.c
+++ b/xdiff/xhistogram.c
@@ -339,21 +339,24 @@ static int histogram_diff(xpparam_t const *xpp, xdfenv_t *env,
        if (find_lcs(&index, &lcs, line1, count1, line2, count2))
                result = fall_back_to_classic_diff(&index, line1, count1, line2, count2);
        else {
-               result = 0;
                if (lcs.begin1 == 0 && lcs.begin2 == 0) {
                        int ptr;
                        for (ptr = 0; ptr < count1; ptr++)
                                env->xdf1.rchg[line1 + ptr - 1] = 1;
                        for (ptr = 0; ptr < count2; ptr++)
                                env->xdf2.rchg[line2 + ptr - 1] = 1;
+                       result = 0;
                } else {
                        result = histogram_diff(xpp, env,
-                               line1, lcs.begin1 - line1,
-                               line2, lcs.begin2 - line2);
+                                               line1, lcs.begin1 - line1,
+                                               line2, lcs.begin2 - line2);
+                       if (result)
+                               goto cleanup;
                        result = histogram_diff(xpp, env,
-                               lcs.end1 + 1, LINE_END(1) - lcs.end1,
-                               lcs.end2 + 1, LINE_END(2) - lcs.end2);
-                       result *= -1;
+                                               lcs.end1 + 1, LINE_END(1) - lcs.end1,
+                                               lcs.end2 + 1, LINE_END(2) - lcs.end2);
+                       if (result)
+                               goto cleanup;
                }
        }