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[patch] Fold ~(X ^ Y) if ~X or ~Y simplify
- From: ja2morri at csclub dot uwaterloo dot ca (James A. Morrison)
- To: gcc-patches at gcc dot gnu dot org
- Date: 19 Apr 2005 22:28:28 -0400
- Subject: [patch] Fold ~(X ^ Y) if ~X or ~Y simplify
Hi,
This patch folds ~(X^Y) into ~X^Y or X^~Y if ~X or ~Y simplify. Bootstrapped
and regtested on ia64-linux. Ok for mainline?
--
Thanks,
Jim
http://www.csclub.uwaterloo.ca/~ja2morri/
http://phython.blogspot.com
http://open.nit.ca/wiki/?page=jim
2005-04-19 James A. Morrison <phython@gcc.gnu.org>
* fold-const.c (fold_binary): Fold ~(X ^ Y) to ~X ^ Y or X ^ ~Y if
~X or ~Y simplify.
Index: fold-const.c
===================================================================
RCS file: /cvsroot/gcc/gcc/gcc/fold-const.c,v
retrieving revision 1.564
diff -u -p -r1.564 fold-const.c
--- fold-const.c 19 Apr 2005 02:35:52 -0000 1.564
+++ fold-const.c 20 Apr 2005 02:13:10 -0000
@@ -7015,6 +7015,20 @@ fold_unary (enum tree_code code, tree ty
|| (TREE_CODE (arg0) == PLUS_EXPR
&& integer_all_onesp (TREE_OPERAND (arg0, 1)))))
return fold_build1 (NEGATE_EXPR, type, TREE_OPERAND (arg0, 0));
+ /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
+ else if (TREE_CODE (arg0) == BIT_XOR_EXPR
+ && (tem = fold_unary (BIT_NOT_EXPR, type,
+ fold_convert (type,
+ TREE_OPERAND (arg0, 0)))))
+ return fold_build2 (BIT_XOR_EXPR, type, tem,
+ fold_convert (type, TREE_OPERAND (arg0, 1)));
+ else if (TREE_CODE (arg0) == BIT_XOR_EXPR
+ && (tem = fold_unary (BIT_NOT_EXPR, type,
+ fold_convert (type,
+ TREE_OPERAND (arg0, 1)))))
+ return fold_build2 (BIT_XOR_EXPR, type,
+ fold_convert (type, TREE_OPERAND (arg0, 0)), tem);
+
return NULL_TREE;
case TRUTH_NOT_EXPR:
testsuite:
* gcc.dg/fold-xor-2.c: New test.
/* { dg-do compile } */
/* { dg-options "-fdump-tree-generic" } */
int f (int a, int b) {
return ~(a ^ -(b + 1));
}
int g (int a, int b) {
return b ^ a;
}
unsigned int h (unsigned int a, unsigned int b) {
return ~(-(b + 1) ^ a);
}
/* { dg-final { scan-tree-dump-times "b \\^ a" 3 "generic" } } */
/* { dg-final { cleanup-tree-dump "generic" } } */