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xdiff/histogram: remove tail recursion

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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>
This commit is contained in:
Stefan Beller
2018-07-19 15:19:42 -07:00
committed by Junio C Hamano
parent 64c4e8bccd
commit 79cb2ebb92
1 changed files with 14 additions and 6 deletions
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20
xdiff/xhistogram.c
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@ -318,7 +318,9 @@ static int histogram_diff(xpparam_t const *xpp, xdfenv_t *env,
{ {
struct region lcs; struct region lcs;
int lcs_found; int lcs_found;
int result = -1; int result;
redo:
result = -1;
if (count1 <= 0 && count2 <= 0) if (count1 <= 0 && count2 <= 0)
return 0; return 0;
@ -355,11 +357,17 @@ static int histogram_diff(xpparam_t const *xpp, xdfenv_t *env,
line2, lcs.begin2 - line2); line2, lcs.begin2 - line2);
if (result) if (result)
goto out; goto out;
result = histogram_diff(xpp, env, /*
lcs.end1 + 1, LINE_END(1) - lcs.end1, * result = histogram_diff(xpp, env,
lcs.end2 + 1, LINE_END(2) - lcs.end2); * lcs.end1 + 1, LINE_END(1) - lcs.end1,
if (result) * lcs.end2 + 1, LINE_END(2) - lcs.end2);
goto out; * 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: out: