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re PR middle-end/27302 (Fold does not fold (i < j) == (j > i) to 1)

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2006-05-10  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/27302
	* fold-const.c (operand_equal_p): For two comparisons,
	try comparison of one comparison code swapped if that yields
	the same code.

	* gcc.dg/torture/pr27302.c: New testcase.

From-SVN: r113670
This commit is contained in:
Richard Guenther 2006-05-10 10:22:39 +00:00 committed by Richard Biener
parent 4db60bd06f
commit a04d8591f2
4 changed files with 43 additions and 0 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2006-05-10 Richard Guenther <rguenther@suse.de>
PR tree-optimization/27302
* fold-const.c (operand_equal_p): For two comparisons,
try comparison of one comparison code swapped if that yields
the same code.
2006-05-10 Ben Elliston <bje@au.ibm.com>
* tree-pretty-print.c (pretty_print_string): No need to handle

16
gcc/fold-const.c
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@ -2489,6 +2489,22 @@ operand_equal_p (tree arg0, tree arg1, unsigned int flags)
STRIP_NOPS (arg0);
STRIP_NOPS (arg1);
/* In case both args are comparisons but with different comparison
code, try to swap the comparison operands of one arg to produce
a match and compare that variant. */
if (TREE_CODE (arg0) != TREE_CODE (arg1)
&& COMPARISON_CLASS_P (arg0)
&& COMPARISON_CLASS_P (arg1))
{
enum tree_code swap_code = swap_tree_comparison (TREE_CODE (arg1));
if (TREE_CODE (arg0) == swap_code)
return operand_equal_p (TREE_OPERAND (arg0, 0),
TREE_OPERAND (arg1, 1), flags)
&& operand_equal_p (TREE_OPERAND (arg0, 1),
TREE_OPERAND (arg1, 0), flags);
}
if (TREE_CODE (arg0) != TREE_CODE (arg1)
/* This is needed for conversions and for COMPONENT_REF.
Might as well play it safe and always test this. */

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2006-05-10 Richard Guenther <rguenther@suse.de>
PR tree-optimization/27302
* gcc.dg/torture/pr27302.c: New testcase.
2006-05-09 Dirk Mueller <dmueller@suse.de>
Richard Guenther <rguenther@suse.de>

15
gcc/testsuite/gcc.dg/torture/pr27302.c Normal file
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@ -0,0 +1,15 @@
/* { dg-do run } */
extern void link_error (void);
void test0 (int a, int b)
{
if ((a < b) != (b > a))
link_error ();
}
int main()
{
test0 (1, 2);
return 0;
}