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re PR tree-optimization/80281 (Wrong constant folding)

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

	PR middle-end/80281
	* match.pd (A + (-B) -> A - B): Make sure to preserve unsigned
	arithmetic done for the negate or the plus.  Simplify.
	(A - (-B) -> A + B): Likewise.
	* fold-const.c (split_tree): Make sure to not negate pointers.

	* gcc.dg/torture/pr80281.c: New testcase.

From-SVN: r246674
This commit is contained in:
Richard Biener 2017-04-04 09:06:04 +00:00 committed by Richard Biener
parent a577fcf2d5
commit 248179b5fc
5 changed files with 60 additions and 12 deletions
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8
gcc/ChangeLog
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@ -1,3 +1,11 @@
2017-04-04 Richard Biener <rguenther@suse.de>
PR middle-end/80281
* match.pd (A + (-B) -> A - B): Make sure to preserve unsigned
arithmetic done for the negate or the plus. Simplify.
(A - (-B) -> A + B): Likewise.
* fold-const.c (split_tree): Make sure to not negate pointers.
2017-04-04 Segher Boessenkool <segher@kernel.crashing.org>
PR rtl-optimization/60818

15
gcc/fold-const.c
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@ -831,8 +831,12 @@ split_tree (location_t loc, tree in, tree type, enum tree_code code,
/* Now do any needed negations. */
if (neg_litp_p)
*minus_litp = *litp, *litp = 0;
if (neg_conp_p)
*conp = negate_expr (*conp);
if (neg_conp_p && *conp)
{
/* Convert to TYPE before negating. */
*conp = fold_convert_loc (loc, type, *conp);
*conp = negate_expr (*conp);
}
if (neg_var_p && var)
{
/* Convert to TYPE before negating. */
@ -859,7 +863,12 @@ split_tree (location_t loc, tree in, tree type, enum tree_code code,
*minus_litp = *litp, *litp = 0;
else if (*minus_litp)
*litp = *minus_litp, *minus_litp = 0;
*conp = negate_expr (*conp);
if (*conp)
{
/* Convert to TYPE before negating. */
*conp = fold_convert_loc (loc, type, *conp);
*conp = negate_expr (*conp);
}
if (var)
{
/* Convert to TYPE before negating. */

30
gcc/match.pd
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@ -1148,19 +1148,31 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
/* Contract negates. */
/* A + (-B) -> A - B */
(simplify
(plus:c (convert1? @0) (convert2? (negate @1)))
/* Apply STRIP_NOPS on @0 and the negate. */
(if (tree_nop_conversion_p (type, TREE_TYPE (@0))
&& tree_nop_conversion_p (type, TREE_TYPE (@1))
(plus:c @0 (convert? (negate @1)))
/* Apply STRIP_NOPS on the negate. */
(if (tree_nop_conversion_p (type, TREE_TYPE (@1))
&& !TYPE_OVERFLOW_SANITIZED (type))
(minus (convert @0) (convert @1))))
(with
{
tree t1 = type;
if (INTEGRAL_TYPE_P (type)
&& TYPE_OVERFLOW_WRAPS (type) != TYPE_OVERFLOW_WRAPS (TREE_TYPE (@1)))
t1 = TYPE_OVERFLOW_WRAPS (type) ? type : TREE_TYPE (@1);
}
(convert (minus (convert:t1 @0) (convert:t1 @1))))))
/* A - (-B) -> A + B */
(simplify
(minus (convert1? @0) (convert2? (negate @1)))
(if (tree_nop_conversion_p (type, TREE_TYPE (@0))
&& tree_nop_conversion_p (type, TREE_TYPE (@1))
(minus @0 (convert? (negate @1)))
(if (tree_nop_conversion_p (type, TREE_TYPE (@1))
&& !TYPE_OVERFLOW_SANITIZED (type))
(plus (convert @0) (convert @1))))
(with
{
tree t1 = type;
if (INTEGRAL_TYPE_P (type)
&& TYPE_OVERFLOW_WRAPS (type) != TYPE_OVERFLOW_WRAPS (TREE_TYPE (@1)))
t1 = TYPE_OVERFLOW_WRAPS (type) ? type : TREE_TYPE (@1);
}
(convert (plus (convert:t1 @0) (convert:t1 @1))))))
/* -(-A) -> A */
(simplify
(negate (convert? (negate @1)))

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2017-04-04 Richard Biener <rguenther@suse.de>
PR middle-end/80281
* gcc.dg/torture/pr80281.c: New testcase.
2017-04-04 Richard Biener <rguenther@suse.de>
PR tree-optimization/80275

14
gcc/testsuite/gcc.dg/torture/pr80281.c Normal file
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@ -0,0 +1,14 @@
/* { dg-run } */
/* { dg-require-effective-target int32plus } */
int
main ()
{
volatile int a = 0;
long long b = 2147483648LL;
int c = a % 2;
int x = ((int) -b + c) % -2147483647;
if (x != -1)
__builtin_abort ();
return 0;
}