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[Bug middle-end/29749] [4.0/4.1/4.2/4.3 regression] Missing byte swap optimizations
- From: "jakub at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 3 Dec 2007 22:38:46 -0000
- Subject: [Bug middle-end/29749] [4.0/4.1/4.2/4.3 regression] Missing byte swap optimizations
- References: <bug-29749-1649@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #15 from jakub at gcc dot gnu dot org 2007-12-03 22:38 -------
Subject: Bug 29749
Author: jakub
Date: Mon Dec 3 22:38:28 2007
New Revision: 130589
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=130589
Log:
PR middle-end/29749
* fold-const.c (fold_binary) <case BIT_AND_EXPR>: Optimize
(X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
and (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1)).
(fold_binary) <case LSHIFT_EXPR, case RSHIFT_EXPR>: Optimize
(X & C2) << C1 into (X << C1) & (C2 << C1) and
(X & C2) >> C1 into (X >> C1) & (C2 >> C1) if that allows further
optimizations.
* gcc.dg/fold-rotate-1.c: New test.
Added:
trunk/gcc/testsuite/gcc.dg/fold-rotate-1.c
Modified:
trunk/gcc/ChangeLog
trunk/gcc/fold-const.c
trunk/gcc/testsuite/ChangeLog
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29749