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From: "vda at port dot imtp dot ilyichevsk dot odessa dot ua" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/21182] gcc can use registers but uses stack instead Date: Sun, 24 Apr 2005 13:05:00 -0000 [thread overview] Message-ID: <20050424130522.27068.qmail@sourceware.org> (raw) In-Reply-To: <20050423223032.21182.vda@port.imtp.ilyichevsk.odessa.ua> ------- Additional Comments From vda at port dot imtp dot ilyichevsk dot odessa dot ua 2005-04-24 13:05 ------- With 4.0.0: gcc -O2 gives the same result as gcc -O3, which is better than gcc 3.4.3 -O2 but worse than 3.4.3 -O3. For example: movl %edx, -20(%ebp) orl %ecx, %edi movl %ebx, %esi xorl %ecx, %esi andl %eax, %ebx xorl %edi, %ebx movl %eax, %ecx notl %ecx xorl %ebx, %ecx orl %edi, %eax xorl %eax, %esi rorl $19, %esi rorl $29, -20(%ebp) xorl %esi, %ebx xorl -20(%ebp), %ecx xorl -20(%ebp), %ebx rorl $31, %ebx leal 0(,%esi,8), %edx 1) Why %edx was stored in -20(%ebp), there is no %edx usage in the following insns. %edx value could stay in register and we can continue to work on its value in register. 2) rorl $31, %ebx == roll $1, %ebx, but 1 bit roll insn is smaller. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21182
next prev parent reply other threads:[~2005-04-24 13:05 UTC|newest] Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top 2005-04-23 22:30 [Bug rtl-optimization/21182] New: " vda at port dot imtp dot ilyichevsk dot odessa dot ua 2005-04-23 22:32 ` [Bug rtl-optimization/21182] " vda at port dot imtp dot ilyichevsk dot odessa dot ua 2005-04-23 22:39 ` pinskia at gcc dot gnu dot org 2005-04-23 22:49 ` vda at port dot imtp dot ilyichevsk dot odessa dot ua 2005-04-23 22:54 ` vda at port dot imtp dot ilyichevsk dot odessa dot ua 2005-04-24 13:05 ` vda at port dot imtp dot ilyichevsk dot odessa dot ua [this message] 2005-05-07 15:24 ` steven at gcc dot gnu dot org [not found] <bug-21182-4@http.gcc.gnu.org/bugzilla/> 2013-01-18 0:48 ` vda.linux at googlemail dot com 2013-01-18 0:51 ` vda.linux at googlemail dot com 2013-01-18 0:55 ` vda.linux at googlemail dot com 2013-01-18 0:57 ` pinskia at gcc dot gnu.org
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