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Fix PR tree-optimization/78598 - tree-ssa-loop-prefetch.c:835:16: runtime error: signed integer overflow

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Using bootstrap-ubsan gcc to build mplayer shows:

tree-ssa-loop-prefetch.c:835:16: runtime error: signed integer overflow:
288230376151711743 * 64 cannot be represented in type 'long int'

Here signed und unsigned integers are mixed in a division resulting in
bogus values: (-83 + 64ULL -1) / 64ULL) == 288230376151711743

Fixed by casting the unsigned parameter to signed.

	PR tree-optimization/78598
	* tree-ssa-loop-prefetch.c (ddown): Cast to signed to avoid
	overflows.

From-SVN: r243113
This commit is contained in:
Markus Trippelsdorf 2016-12-01 14:59:03 +00:00 committed by Markus Trippelsdorf
parent be5ddbb86f
commit 56e1a4d712
2 changed files with 8 additions and 2 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2016-12-01 Markus Trippelsdorf <markus@trippelsdorf.de>
PR tree-optimization/78598
* tree-ssa-loop-prefetch.c (ddown): Cast to signed to avoid
overflows.
2016-12-01 Markus Trippelsdorf <markus@trippelsdorf.de>
PR rtl-optimization/78596

4
gcc/tree-ssa-loop-prefetch.c
View File

@ -700,9 +700,9 @@ ddown (HOST_WIDE_INT x, unsigned HOST_WIDE_INT by)
gcc_assert (by > 0);
if (x >= 0)
return x / by;
return x / (HOST_WIDE_INT) by;
else
return (x + by - 1) / by;
return (x + (HOST_WIDE_INT) by - 1) / (HOST_WIDE_INT) by;
}
/* Given a CACHE_LINE_SIZE and two inductive memory references