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[Committed] Handle XOR in tree_expr_nonnegative_p
- From: Roger Sayle <roger at eyesopen dot com>
- To: gcc-patches at gcc dot gnu dot org
- Cc: Hakan Hjort <hakan dot hjort at safelogic dot se>
- Date: Thu, 25 Mar 2004 17:12:48 -0700 (MST)
- Subject: [Committed] Handle XOR in tree_expr_nonnegative_p
Many thanks to Hakan Hjort for pointing out another optimization
that I'd missed in my recent tweak to tree_expr_nonnegative_p.
The expression "A ^ B" is nonnegative, if A and B are nonnegative.
The following patch has been tested on i686-pc-linux-gnu with a
full "make bootstrap", all languages except treelang, and regression
tested with a top-level "make -k check" with no new failures.
Committed to mainline.
2004-03-25 Roger Sayle <roger@eyesopen.com>
* fold-const.c (tree_expr_nonnegative_p): Handle BIT_XOR_EXPR like
BIT_IOR_EXPR; A^B is nonnegative when A and B are nonnegative.
* gcc.dg/compare8.c: Add an additional test for XOR.
Index: fold-const.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/fold-const.c,v
retrieving revision 1.358
diff -c -3 -p -r1.358 fold-const.c
*** fold-const.c 23 Mar 2004 19:11:35 -0000 1.358
--- fold-const.c 24 Mar 2004 23:34:56 -0000
*************** tree_expr_nonnegative_p (tree t)
*** 8721,8726 ****
--- 8721,8727 ----
return tree_expr_nonnegative_p (TREE_OPERAND (t, 1))
|| tree_expr_nonnegative_p (TREE_OPERAND (t, 0));
case BIT_IOR_EXPR:
+ case BIT_XOR_EXPR:
return tree_expr_nonnegative_p (TREE_OPERAND (t, 0))
&& tree_expr_nonnegative_p (TREE_OPERAND (t, 1));
Index: compare8.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/testsuite/gcc.dg/compare8.c,v
retrieving revision 1.1
diff -c -3 -p -r1.1 compare8.c
*** compare8.c 24 Mar 2004 00:19:06 -0000 1.1
--- compare8.c 25 Mar 2004 17:02:24 -0000
*************** g(unsigned short a1, unsigned short a2,
*** 13,15 ****
--- 13,21 ----
return ((a1+a2)&5) > b ? 2 : 3; /* { dg-bogus "signed and unsigned" } */
}
+ int
+ h(unsigned short a1, unsigned short a2, unsigned int b)
+ {
+ return ((a1+a2)^5) > b ? 2 : 3; /* { dg-bogus "signed and unsigned" } */
+ }
+
Roger
--
Roger Sayle, E-mail: roger@eyesopen.com
OpenEye Scientific Software, WWW: http://www.eyesopen.com/
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