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re PR middle-end/81088 (UBSAN: false positive as a result of reassosiation)

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2017-06-14  Richard Biener  <rguenther@suse.de>

	PR middle-end/81088
	* fold-const.c (split_tree): Drop TREE_OVERFLOW flag from
	literal constants.
	(fold_binary_loc): When associating do not treat pre-existing
	TREE_OVERFLOW on literal constants as a reason to allow
	TREE_OVERFLOW on associated literal constants.

	* c-c++-common/ubsan/pr81088.c: New testcase.

From-SVN: r249192
This commit is contained in:
Richard Biener 2017-06-14 11:40:20 +00:00 • committed by Richard Biener
parent c74985e3ee
commit 909263f855
4 changed files with 34 additions and 8 deletions
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9
gcc/ChangeLog
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@ -1,3 +1,12 @@
2017-06-14 Richard Biener <rguenther@suse.de>
PR middle-end/81088
* fold-const.c (split_tree): Drop TREE_OVERFLOW flag from
literal constants.
(fold_binary_loc): When associating do not treat pre-existing
TREE_OVERFLOW on literal constants as a reason to allow
TREE_OVERFLOW on associated literal constants.
2017-06-14 Eric Botcazou <ebotcazou@adacore.com>
* config/sparc/sparc.h (MASK_ISA): Add MASK_LEON and MASK_LEON3.

17
gcc/fold-const.c
View file

@ -880,6 +880,13 @@ split_tree (location_t loc, tree in, tree type, enum tree_code code,
}
}
if (*litp
&& TREE_OVERFLOW_P (*litp))
*litp = drop_tree_overflow (*litp);
if (*minus_litp
&& TREE_OVERFLOW_P (*minus_litp))
*minus_litp = drop_tree_overflow (*minus_litp);
return var;
}
@ -9703,11 +9710,6 @@ fold_binary_loc (location_t loc,
+ (lit0 != 0) + (lit1 != 0)
+ (minus_lit0 != 0) + (minus_lit1 != 0))))
{
bool any_overflows = false;
if (lit0) any_overflows |= TREE_OVERFLOW (lit0);
if (lit1) any_overflows |= TREE_OVERFLOW (lit1);
if (minus_lit0) any_overflows |= TREE_OVERFLOW (minus_lit0);
if (minus_lit1) any_overflows |= TREE_OVERFLOW (minus_lit1);
var0 = associate_trees (loc, var0, var1, code, atype);
con0 = associate_trees (loc, con0, con1, code, atype);
lit0 = associate_trees (loc, lit0, lit1, code, atype);
@ -9738,9 +9740,8 @@ fold_binary_loc (location_t loc,
}
/* Don't introduce overflows through reassociation. */
if (!any_overflows
&& ((lit0 && TREE_OVERFLOW_P (lit0))
|| (minus_lit0 && TREE_OVERFLOW_P (minus_lit0))))
if ((lit0 && TREE_OVERFLOW_P (lit0))
|| (minus_lit0 && TREE_OVERFLOW_P (minus_lit0)))
return NULL_TREE;
if (minus_lit0)

5
gcc/testsuite/ChangeLog
View file

@ -1,3 +1,8 @@
2017-06-14 Richard Biener <rguenther@suse.de>
PR middle-end/81088
* c-c++-common/ubsan/pr81088.c: New testcase.
2017-06-14 Eric Botcazou <ebotcazou@adacore.com>
* gcc.target/sparc/overflow-4.c: Add -mno-vis3.

11
gcc/testsuite/c-c++-common/ubsan/pr81088.c Normal file
View file

@ -0,0 +1,11 @@
/* { dg-do run } */
/* { dg-options "-fsanitize=undefined -fsanitize-undefined-trap-on-error" } */
short s = 2;
short y = 1;
int i;
int main()
{
i = -(s + (int)(~(unsigned)(0 / y))) + 0x7fffffff;
return 0;
}