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authorStefan Beller <sbeller@google.com>2018-07-19 22:19:42 (GMT)
committerJunio C Hamano <gitster@pobox.com>2018-07-23 17:12:16 (GMT)
commit79cb2ebb92c18af11edf5eea238425d86eef173d (patch)
tree3e41f104e579b7940af35b79d70e17b2312ba8ce
parent64c4e8bccde9d357f6b7adf5277c3157b2bd0d42 (diff)
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xdiff/histogram: remove tail recursion
When running the same reproduction script as the previous patch, it turns out the stack is too small, which can be easily avoided. Signed-off-by: Stefan Beller <sbeller@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
-rw-r--r--xdiff/xhistogram.c20
1 files changed, 14 insertions, 6 deletions
diff --git a/xdiff/xhistogram.c b/xdiff/xhistogram.c
index fc2d3cd..ec85f59 100644
--- a/xdiff/xhistogram.c
+++ b/xdiff/xhistogram.c
@@ -318,7 +318,9 @@ static int histogram_diff(xpparam_t const *xpp, xdfenv_t *env,
{
struct region lcs;
int lcs_found;
- int result = -1;
+ int result;
+redo:
+ result = -1;
if (count1 <= 0 && count2 <= 0)
return 0;
@@ -355,11 +357,17 @@ static int histogram_diff(xpparam_t const *xpp, xdfenv_t *env,
line2, lcs.begin2 - line2);
if (result)
goto out;
- result = histogram_diff(xpp, env,
- lcs.end1 + 1, LINE_END(1) - lcs.end1,
- lcs.end2 + 1, LINE_END(2) - lcs.end2);
- if (result)
- goto out;
+ /*
+ * result = histogram_diff(xpp, env,
+ * lcs.end1 + 1, LINE_END(1) - lcs.end1,
+ * lcs.end2 + 1, LINE_END(2) - lcs.end2);
+ * but let's optimize tail recursion ourself:
+ */
+ count1 = LINE_END(1) - lcs.end1;
+ line1 = lcs.end1 + 1;
+ count2 = LINE_END(2) - lcs.end2;
+ line2 = lcs.end2 + 1;
+ goto redo;
}
}
out: