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From: "steven at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/6585] Redundant store/load instruction pairs on ix86 Date: Sun, 26 Jun 2005 13:35:00 -0000 [thread overview] Message-ID: <20050626133546.20712.qmail@sourceware.org> (raw) In-Reply-To: <20020506130600.6585.bruno@clisp.org> ------- Additional Comments From steven at gcc dot gnu dot org 2005-06-26 13:35 ------- Today's results ("-O2 -m32 -march=i686 -mtune=i686 -fomit-frame-pointer"): .file "t.c" .text .p2align 4,,15 .globl mul .type mul, @function mul: subl $12, %esp # get space to save three registers movl %ebx, (%esp) # save %ebx movl 20(%esp), %edx # %edx <- a1 COULD GO INTO %esi movl 28(%esp), %ebx # %ebx <- b1 COULD GO INTO %edi movl 16(%esp), %eax # %eax <- a0 movl 24(%esp), %ecx # %ecx <- b0 movl %esi, 4(%esp) # save %esi movl %edx, %esi # %esi <- a1 movl %edi, 8(%esp) # save %edi movl %ebx, %edi # %edi <- b1 movl (%esp), %ebx # restore %ebx imull %eax, %edi # %edi <- a0*b1 imull %ecx, %esi # %esi <- b0*a1 mull %ecx # %edx:%eax := a0*b0 addl %edi, %esi # %esi <- a0*b1 + b0*a1 movl 8(%esp), %edi # restore %edi leal (%esi,%edx), %edx # %edx <- a0*b1 + b0*a1 + hi(a0*b0) movl 4(%esp), %esi # %restore %esi addl $12, %esp # free stack space ret # return result in %edx:%eax .size mul, .-mul .ident "GCC: (GNU) 4.1.0 20050626 (experimental)" .section .note.GNU-stack,"",@progbits There are still the questionable moves through %ebx and %edx, but it is still better than before. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=6585
next prev parent reply other threads:[~2005-06-26 13:35 UTC|newest] Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <20020506130600.6585.bruno@clisp.org> 2003-07-04 11:09 ` [Bug optimization/6585] useless memory store instructions on x86 steven at gcc dot gnu dot org 2003-07-10 20:09 ` [Bug optimization/6585] Reduntant store/load instruction pairs on ix86 steven at gcc dot gnu dot org 2003-08-23 1:38 ` [Bug optimization/6585] Redundant " dhazeghi at yahoo dot com 2003-11-25 7:51 ` pinskia at gcc dot gnu dot org 2004-03-17 8:03 ` kazu at cs dot umass dot edu 2004-03-17 12:10 ` bruno at clisp dot org 2004-10-11 2:57 ` [Bug rtl-optimization/6585] " pinskia at gcc dot gnu dot org 2004-10-11 11:55 ` bruno at clisp dot org 2005-06-26 13:35 ` steven at gcc dot gnu dot org [this message] 2005-06-27 11:50 ` bruno at clisp dot org [not found] <bug-6585-128@http.gcc.gnu.org/bugzilla/> 2007-11-23 6:02 ` ismail at pardus dot org dot tr 2007-11-23 7:37 ` steven at gcc dot gnu dot org 2007-11-23 7:43 ` ubizjak at gmail dot com 2007-11-23 20:43 ` rask at gcc dot gnu dot org 2007-11-23 20:48 ` steven at gcc dot gnu dot org 2007-12-19 14:15 ` rask at gcc dot gnu dot org 2008-09-06 16:19 ` ubizjak at gmail dot com
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