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fold-const.c (fold_comparison): Fold ~X op ~Y as Y op X. 

* fold-const.c (fold_comparison): Fold ~X op ~Y as Y op X.
	Fold ~X op C as X op' ~C, where op' is the swapped comparison.
	(fold_binary): ~X eq/ne C is now handled in fold_comparison.
	Fold -X eq/ne -Y as X eq/ne Y.

	* gcc.dg/fold-compare-1.c: New test case.

From-SVN: r118158
This commit is contained in:
Roger Sayle 2006-10-29 21:41:48 +00:00 committed by Roger Sayle
parent 153ae66aee
commit c159ffe706
4 changed files with 86 additions and 7 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2006-10-29 Roger Sayle <roger@eyesopen.com>
* fold-const.c (fold_comparison): Fold ~X op ~Y as Y op X.
Fold ~X op C as X op' ~C, where op' is the swapped comparison.
(fold_binary): ~X eq/ne C is now handled in fold_comparison.
Fold -X eq/ne -Y as X eq/ne Y.
2006-10-29 Richard Sandiford <richard@codesourcery.com>
* config/mips/mips.md (mul<mode>3): Check ISA_HAS_MUL3 rather than

29
gcc/fold-const.c
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@ -8360,6 +8360,20 @@ fold_comparison (enum tree_code code, tree type, tree op0, tree op1)
return tem;
}
/* Fold ~X op ~Y as Y op X. */
if (TREE_CODE (arg0) == BIT_NOT_EXPR
&& TREE_CODE (arg1) == BIT_NOT_EXPR)
return fold_build2 (code, type,
TREE_OPERAND (arg1, 0),
TREE_OPERAND (arg0, 0));
/* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
if (TREE_CODE (arg0) == BIT_NOT_EXPR
&& TREE_CODE (arg1) == INTEGER_CST)
return fold_build2 (swap_tree_comparison (code), type,
TREE_OPERAND (arg0, 0),
fold_build1 (BIT_NOT_EXPR, TREE_TYPE (arg1), arg1));
return NULL_TREE;
}
@ -10426,13 +10440,6 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1)
&& code == EQ_EXPR)
return fold_build1 (TRUTH_NOT_EXPR, type, arg0);
/* ~a != C becomes a != ~C where C is a constant. Likewise for ==. */
if (TREE_CODE (arg0) == BIT_NOT_EXPR
&& TREE_CODE (arg1) == INTEGER_CST)
return fold_build2 (code, type, TREE_OPERAND (arg0, 0),
fold_build1 (BIT_NOT_EXPR, TREE_TYPE (arg1),
arg1));
/* If this is an equality comparison of the address of a non-weak
object against zero, then we know the result. */
if (TREE_CODE (arg0) == ADDR_EXPR
@ -10798,6 +10805,14 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1)
tree res = constant_boolean_node (code==NE_EXPR, type);
return omit_one_operand (type, res, arg0);
}
/* Fold -X op -Y as X op Y, where op is eq/ne. */
if (TREE_CODE (arg0) == NEGATE_EXPR
&& TREE_CODE (arg1) == NEGATE_EXPR)
return fold_build2 (code, type,
TREE_OPERAND (arg0, 0),
TREE_OPERAND (arg1, 0));
return NULL_TREE;
case LT_EXPR:

4
gcc/testsuite/ChangeLog
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@ -1,3 +1,7 @@
2006-10-29 Roger Sayle <roger@eyesopen.com>
* gcc.dg/fold-compare-1.c: New test case.
2006-10-29 Dirk Mueller <dmueller@suse.de>
PR c++/16307

53
gcc/testsuite/gcc.dg/fold-compare-1.c Normal file
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@ -0,0 +1,53 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-original" } */
int test1(int a, int b)
{
return ~a == ~b;
}
int test2(int c, int d)
{
return -c == -d;
}
int test3(int e)
{
return -e == 5;
}
int test4(int f)
{
return ~f == 5;
}
int test5(int g, int h)
{
return ~g < ~h;
}
int test6(int i, int j)
{
return ~i >= ~j;
}
int test7(int k)
{
return ~k < 3;
}
int test8(int l)
{
return ~l >= 2;
}
/* { dg-final { scan-tree-dump-times "b == a" 1 "original" } } */
/* { dg-final { scan-tree-dump-times "c == d" 1 "original" } } */
/* { dg-final { scan-tree-dump-times "e == -5" 1 "original" } } */
/* { dg-final { scan-tree-dump-times "f == -6" 1 "original" } } */
/* { dg-final { scan-tree-dump-times "h < g" 1 "original" } } */
/* { dg-final { scan-tree-dump-times "j >= i" 1 "original" } } */
/* { dg-final { scan-tree-dump-times "k > -4" 1 "original" } } */
/* { dg-final { scan-tree-dump-times "l <= -3" 1 "original" } } */
/* { dg-final { cleanup-tree-dump "original" } } */