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re PR middle-end/81705 (UBSAN: yet another false positive)

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2017-08-04  Richard Biener  <rguenther@suse.de>

	PR middle-end/81705
	* fold-const.c (fold_binary_loc): Properly restrict
	minus_var0 && minus_var1 case when associating undefined overflow
	entities.

	* c-c++-common/ubsan/pr81705.c: New testcase.

From-SVN: r250866
This commit is contained in:
Richard Biener 2017-08-04 10:33:39 +00:00 committed by Richard Biener
parent 54cb4e2006
commit 165b2f5f5d
4 changed files with 29 additions and 4 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2017-08-04 Richard Biener <rguenther@suse.de>
PR middle-end/81705
* fold-const.c (fold_binary_loc): Properly restrict
minus_var0 && minus_var1 case when associating undefined overflow
entities.
2017-08-04 Tom de Vries <tom@codesourcery.com>
* omp-simd-clone.c (simd_clone_adjust): Add missing edge probability.

9
gcc/fold-const.c
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@ -9592,12 +9592,13 @@ fold_binary_loc (location_t loc,
if (POINTER_TYPE_P (atype)
|| (INTEGRAL_TYPE_P (atype) && !TYPE_OVERFLOW_WRAPS (atype)))
{
if (var0 && var1)
if ((var0 && var1) || (minus_var0 && minus_var1))
{
/* ??? If split_tree would handle NEGATE_EXPR we could
simplify this down to the var0/minus_var1 cases. */
tree tmp0 = var0;
tree tmp1 = var1;
simply reject these cases and the allowed cases would
be the var0/minus_var1 ones. */
tree tmp0 = var0 ? var0 : minus_var0;
tree tmp1 = var1 ? var1 : minus_var1;
bool one_neg = false;
if (TREE_CODE (tmp0) == NEGATE_EXPR)

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2017-08-04 Richard Biener <rguenther@suse.de>
PR middle-end/81705
* c-c++-common/ubsan/pr81705.c: New testcase.
2017-08-03 Bill Schmidt <wschmidt@linux.vnet.ibm.com>
* gcc.target/powerpc/bfp/scalar-cmp-exp-eq-2.c: Adjust for error

12
gcc/testsuite/c-c++-common/ubsan/pr81705.c Normal file
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@ -0,0 +1,12 @@
/* { dg-do run } */
/* { dg-options "-fsanitize=undefined -fsanitize-undefined-trap-on-error" } */
int var_4 = -1716607962;
int var_14 = 943738830;
volatile int a;
int main()
{
// (-(-1716607962) - 516151698) - -(9403738830)
a = (-var_4 - 516151698) - -var_14;
return 0;
}