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From: "rask at sygehus dot dk" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/21137] Convert (a >> 2) & 1 != 0 into a & 4 != 0 Date: Tue, 24 Jul 2007 14:57:00 -0000 [thread overview] Message-ID: <20070724145654.1721.qmail@sourceware.org> (raw) In-Reply-To: <bug-21137-5009@http.gcc.gnu.org/bugzilla/> ------- Comment #9 from rask at sygehus dot dk 2007-07-24 14:56 ------- This is not fully fixed yet. Compile these two functions with -O2 -fdump-tree-original: void test5_1(int e) { if ((e >> 31) & 64) foo(); } typedef int myint; void test5_2(myint e) { if ((e >> 31) & 64) foo(); } On x86_64-unknown-linux-gnu, I get (4.2.0, 4.2.1 and mainline): ;; Function test5_1 (test5_1) ;; enabled by -tree-original { if (e < 0) { foo (); } } ;; Function test5_2 (test5_2) ;; enabled by -tree-original { if (((int) (e >> 31) & 64) != 0) { foo (); } } We should get identical dumps for the two functions. I noticed this problem while trying to fix the original testcase to work targets where an int is not exactly 32 bits wide. The attached patch to fix the testcase revealed the problem. -- rask at sygehus dot dk changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |rask at sygehus dot dk http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21137
next prev parent reply other threads:[~2007-07-24 14:57 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <bug-21137-5009@http.gcc.gnu.org/bugzilla/> 2006-02-26 15:37 ` sayle at gcc dot gnu dot org 2006-02-26 18:47 ` roger at eyesopen dot com 2007-07-24 14:57 ` rask at sygehus dot dk [this message] 2007-07-24 15:00 ` rask at sygehus dot dk 2007-07-26 9:34 ` rask at gcc dot gnu dot org 2007-07-30 1:47 ` pinskia at gcc dot gnu dot org [not found] <20050421004702.21137.kazu@gcc.gnu.org> 2005-07-11 4:16 ` phython at gcc dot gnu dot org 2005-08-14 19:17 ` roger at eyesopen dot com 2005-08-14 21:56 ` phython at gcc dot gnu dot org 2005-04-21 0:47 [Bug tree-optimization/21137] New: " kazu at cs dot umass dot edu 2005-04-21 0:50 ` [Bug middle-end/21137] " pinskia at gcc dot gnu dot org
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