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From: "astrange at ithinksw dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/40992] New: [4.2/4.3/4.4/4.5 Regression] cunroll ignoring asm size Date: Fri, 07 Aug 2009 04:25:00 -0000 [thread overview] Message-ID: <bug-40992-10175@http.gcc.gnu.org/bugzilla/> (raw) The attached file is a loop over the same function implemented in C and inline asm. When compiled with: gcc -O3 -fno-pic -fomit-frame-pointer -fdump-tree-cunroll-details -S cabac_unroll.i cunroll thinks they're different sizes: size: 55-4, last_iteration: 55-4 Loop size: 55 Estimated size after unrolling: 442 size: 8-4, last_iteration: 8-4 Loop size: 8 Estimated size after unrolling: 34 and expands the asm loop all 13 times. This is reduced from ffmpeg decode_cabac_residual, where it apparently causes significant decoding slowdown. Besides that, cunroll seems to be hurting ffmpeg in general on x86-32 (http://multimedia.cx/eggs/last-performance-smackdown-for-awhile/), maybe we'll turn it down some. -- Summary: [4.2/4.3/4.4/4.5 Regression] cunroll ignoring asm size Product: gcc Version: 4.5.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: astrange at ithinksw dot com http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40992
next reply other threads:[~2009-08-07 4:25 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2009-08-07 4:25 astrange at ithinksw dot com [this message] 2009-08-07 4:25 ` [Bug tree-optimization/40992] " astrange at ithinksw dot com 2009-08-07 12:07 ` rguenth at gcc dot gnu dot org 2009-08-08 16:44 ` astrange at ithinksw dot com 2009-08-16 21:40 ` [Bug tree-optimization/40992] [4.3/4.4/4.5 " rguenth at gcc dot gnu dot org 2009-08-16 21:42 ` rguenth at gcc dot gnu dot org 2009-10-05 0:40 ` pinskia at gcc dot gnu dot org 2009-10-05 0:56 ` pinskia at gcc dot gnu dot org 2009-10-05 0:57 ` pinskia at gcc dot gnu dot org 2009-10-05 17:47 ` [Bug tree-optimization/40992] [4.3/4.4 " pinskia at gcc dot gnu dot org 2009-10-05 17:47 ` pinskia at gcc dot gnu dot org 2010-05-22 18:33 ` rguenth at gcc dot gnu dot org
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