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From: "kazu at cs dot umass dot edu" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug optimization/14504] Missed Bit Twiddling Optimization Date: Thu, 11 Mar 2004 00:09:00 -0000 [thread overview] Message-ID: <20040311000929.31207.qmail@sources.redhat.com> (raw) In-Reply-To: <20040309171658.14504.stl@caltech.edu> ------- Additional Comments From kazu at cs dot umass dot edu 2004-03-11 00:09 ------- I've got a patch. /* There are four cases to handle modulo whether FLAG appears positively and ordering of operands TARGET and MASK in the expression. With my patch, gcc -O2 -fomit-frame-pointer -mregparm=3 generates the following assembly code. */ typedef _Bool bool; unsigned long cond_mask_0 (bool flag, unsigned long mask, unsigned long target) { return flag ? target | mask : target & ~mask; #if 0 movzbl %al, %eax decl %eax xorl %eax, %ecx orl %edx, %ecx xorl %ecx, %eax #endif } unsigned long cond_mask_1 (bool flag, unsigned long mask, unsigned long target) { return flag ? target | ~mask : target & mask; #if 0 movzbl %al, %eax negl %eax xorl %eax, %ecx andl %edx, %ecx xorl %ecx, %eax #endif } unsigned long cond_mask_2 (bool flag, unsigned long mask, unsigned long target) { return flag ? target & mask : target | ~mask; #if 0 movzbl %al, %eax decl %eax xorl %eax, %ecx andl %edx, %ecx xorl %ecx, %eax #endif } unsigned long cond_mask_3 (bool flag, unsigned long mask, unsigned long target) { return flag ? target & ~mask : target | mask; #if 0 movzbl %al, %eax negl %eax xorl %eax, %ecx orl %edx, %ecx xorl %ecx, %eax #endif } -- What |Removed |Added ---------------------------------------------------------------------------- CC| |kazu at cs dot umass dot edu AssignedTo|unassigned at gcc dot gnu |kazu at cs dot umass dot edu |dot org | Status|NEW |ASSIGNED http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14504
next prev parent reply other threads:[~2004-03-11 0:09 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2004-03-09 17:17 [Bug optimization/14504] New: " stl at caltech dot edu 2004-03-09 17:35 ` [Bug optimization/14504] " pinskia at gcc dot gnu dot org 2004-03-09 18:01 ` [Bug optimization/14504] New: " Falk Hueffner 2004-03-11 0:09 ` kazu at cs dot umass dot edu [this message] 2004-03-11 21:33 ` [Bug optimization/14504] " stl at caltech dot edu 2004-03-11 21:35 ` kazu at cs dot umass dot edu 2004-03-11 21:41 ` stl at caltech dot edu 2004-03-11 22:10 ` falk at debian dot org 2004-03-11 22:21 ` stl at caltech dot edu 2004-03-11 22:29 ` kazu at cs dot umass dot edu
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