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From: "ktietz at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/47477] [4.7/4.8/4.9 regression] Sub-optimal mov at end of method Date: Tue, 22 Oct 2013 14:18:00 -0000 [thread overview] Message-ID: <bug-47477-4-pbUtFjHIEp@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-47477-4@http.gcc.gnu.org/bugzilla/> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47477 --- Comment #17 from Kai Tietz <ktietz at gcc dot gnu.org> --- What optimization you expect here? I see by the new type-demotion pass some changes in optimized tree-output: foo () { int i; short int _4; char _5; unsigned short _6; unsigned short _8; short int _9; unsigned short _10; unsigned short _11; short int _12; sizetype _25; <bb 2>: goto <bb 4>; <bb 3>: <bb 4>: # i_17 = PHI <i_14(3), 0(2)> _25 = (sizetype) i_17; _4 = MEM[symbol: a, index: _25, step: 2, offset: 0B]; _5 = (char) _4; _6 = (unsigned short) _5; _9 = MEM[symbol: b, index: _25, step: 2, offset: 0B]; _8 = (unsigned short) _9; _10 = _8 + 17; _11 = _10 + _6; _12 = (short int) _11; MEM[symbol: a, index: _25, step: 2, offset: 0B] = _12; i_14 = i_17 + 1; if (i_14 != 1024) goto <bb 3>; else goto <bb 5>; <bb 5>: return; } what then gets simplified to the following assembler on IA32: _foo: xorl %eax, %eax .p2align 4,,10 L2: movsbw _a(%eax,%eax), %dx movzwl _b(%eax,%eax), %ecx leal 17(%ecx,%edx), %edx movw %dx, _a(%eax,%eax) addl $1, %eax cmpl $1024, %eax jne L2 rep ret The same assembler gets produced for my with all compilers back to 4.6.0, just tree-optimization output differs.
next prev parent reply other threads:[~2013-10-22 14:18 UTC|newest] Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top 2011-01-26 16:54 [Bug rtl-optimization/47477] New: [4.6 " tony.poppleton at gmail dot com 2011-01-27 7:08 ` [Bug rtl-optimization/47477] " hjl.tools at gmail dot com 2011-01-27 11:51 ` rguenth at gcc dot gnu.org 2011-01-27 17:34 ` jakub at gcc dot gnu.org 2011-01-27 17:58 ` jakub at gcc dot gnu.org 2011-01-27 19:43 ` tony.poppleton at gmail dot com 2011-01-28 11:31 ` rguenth at gcc dot gnu.org 2011-01-29 20:37 ` jakub at gcc dot gnu.org 2011-02-08 14:40 ` rguenth at gcc dot gnu.org 2011-02-08 14:41 ` rguenth at gcc dot gnu.org 2011-02-21 16:19 ` jakub at gcc dot gnu.org 2012-01-02 11:36 ` [Bug rtl-optimization/47477] [4.6/4.7/4.8 " jakub at gcc dot gnu.org 2012-03-06 12:48 ` jakub at gcc dot gnu.org 2012-11-30 16:27 ` jakub at gcc dot gnu.org 2013-03-22 14:46 ` [Bug rtl-optimization/47477] [4.6/4.7/4.8/4.9 " jakub at gcc dot gnu.org 2013-04-10 1:44 ` tony.poppleton at gmail dot com 2013-05-31 11:03 ` [Bug rtl-optimization/47477] [4.7/4.8/4.9 " jakub at gcc dot gnu.org 2013-10-16 9:49 ` jakub at gcc dot gnu.org 2013-10-22 13:40 ` jakub at gcc dot gnu.org 2013-10-22 14:18 ` ktietz at gcc dot gnu.org [this message] 2013-10-22 14:56 ` jakub at gcc dot gnu.org 2014-05-22 9:07 ` [Bug rtl-optimization/47477] [4.7/4.8/4.9/4.10 " rguenth at gcc dot gnu.org 2014-12-19 13:40 ` [Bug rtl-optimization/47477] [4.8/4.9/5 " jakub at gcc dot gnu.org 2015-02-13 20:18 ` law at gcc dot gnu.org 2015-02-13 20:20 ` [Bug rtl-optimization/47477] [4.8/4.9 " law at redhat dot com 2015-02-17 5:22 ` law at redhat dot com 2015-06-23 8:20 ` rguenth at gcc dot gnu.org 2015-06-26 20:13 ` [Bug rtl-optimization/47477] [4.9 " jakub at gcc dot gnu.org 2015-06-26 20:35 ` jakub at gcc dot gnu.org
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