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re PR c/39855 (Shift optimization discards operands' side effects) 

PR c/39855
	* fold-const.c (fold_binary) <case LSHIFT_EXPR>: When optimizing
	into 0, use omit_one_operand.

	* gcc.dg/torture/pr39855.c: New test.

From-SVN: r146622
This commit is contained in:
Jakub Jelinek 2009-04-23 00:02:54 +02:00 committed by Jakub Jelinek
parent 031828f46e
commit 82ec928fcd
4 changed files with 35 additions and 1 deletions
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4
gcc/ChangeLog
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@ -3,6 +3,10 @@
* alias.c (find_base_term): Move around LO_SUM case, so that
CONST falls through into PLUS/MINUS handling.
PR c/39855
* fold-const.c (fold_binary) <case LSHIFT_EXPR>: When optimizing
into 0, use omit_one_operand.
2009-04-22 Vladimir Makarov <vmakarov@redhat.com>
PR rtl-optimization/39762

3
gcc/fold-const.c
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@ -11861,7 +11861,8 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1)
if (code == LROTATE_EXPR || code == RROTATE_EXPR)
low = low % TYPE_PRECISION (type);
else if (TYPE_UNSIGNED (type) || code == LSHIFT_EXPR)
return build_int_cst (type, 0);
return omit_one_operand (type, build_int_cst (type, 0),
TREE_OPERAND (arg0, 0));
else
low = TYPE_PRECISION (type) - 1;
}

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2009-04-22 Jakub Jelinek <jakub@redhat.com>
PR c/39855
* gcc.dg/torture/pr39855.c: New test.
2009-04-22 Richard Guenther <rguenther@suse.de>
PR tree-optimization/39824

24
gcc/testsuite/gcc.dg/torture/pr39855.c Normal file
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@ -0,0 +1,24 @@
/* PR c/39855 */
/* { dg-do run { target { int32plus } } } */
extern void abort (void);
int i, j, k;
int
foo (void)
{
return ++i;
}
int
main ()
{
if (__CHAR_BIT__ != 8 || sizeof (int) != 4)
return 0;
j = foo () << 30 << 2;
k = (unsigned) foo () >> 16 >> 16;
if (i != 2 || j != 0 || k != 0)
abort ();
return 0;
}