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From: "tbptbp at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/19240] New: runtime performance regression in floating point heavy code, x86/SSE Date: Mon, 03 Jan 2005 13:13:00 -0000 [thread overview] Message-ID: <20050103131301.19240.tbptbp@gmail.com> (raw) I'm seeing a significant runtime performance regression (>15%) with snapshots following gcc-4.0-20041205; as far as i can see there's some issues when the register pressure builds up: in later versions the fpu gets involved when former version didn't. The >15% figure comes from larger application (a raytracer), branch predictions also changed (but i've fixed that) so i'm reasonably sure the problem is what's demonstrated in the attached testcase. Switches: -march=k8 -mfpmath=sse -O3 -ffast-math -fomit-frame-pointer with gcc-4.0-20041205: [snip] 4010f4: movss (%ecx,%esi,4),%xmm0 4010f9: movss (%eax,%ebx,4),%xmm5 4010fe: movss (%eax,%esi,4),%xmm7 401103: mulss %xmm5,%xmm1 401107: movss (%ecx,%ebx,4),%xmm4 40110c: movss %xmm0,(%esp) 401111: mulss %xmm4,%xmm2 401115: movaps %xmm3,%xmm0 401118: subss (%ecx,%edx,4),%xmm6 40111d: addss (%eax,%edx,4),%xmm1 401122: mulss (%esp),%xmm3 401127: mulss %xmm7,%xmm0 40112b: subss %xmm2,%xmm6 40112f: xorps %xmm2,%xmm2 401132: addss %xmm0,%xmm1 401136: subss %xmm3,%xmm6 40113a: divss %xmm1,%xmm6 40113e: mulss %xmm6,%xmm7 401142: comiss 0x0(%ebp),%xmm6 401146: mulss %xmm6,%xmm5 40114a: addss (%esp),%xmm7 with gcc-4.0-20050102: [snip] 4010ff: movss (%ecx,%esi,4),%xmm0 401104: movss (%eax,%ebx,4),%xmm5 401109: movss (%eax,%esi,4),%xmm7 40110e: mulss %xmm5,%xmm1 401112: movss (%ecx,%ebx,4),%xmm4 401117: movss %xmm0,0x4(%esp) 40111d: mulss %xmm4,%xmm2 401121: movaps %xmm3,%xmm0 401124: flds (%ecx,%edx,4) 401127: addss (%eax,%edx,4),%xmm1 40112c: mulss 0x4(%esp),%xmm3 401132: fsubrs 0xc(%edi) 401135: mulss %xmm7,%xmm0 401139: addss %xmm0,%xmm1 40113d: fstps (%esp) 401140: movss (%esp),%xmm6 401145: subss %xmm2,%xmm6 401149: xorps %xmm2,%xmm2 40114c: subss %xmm3,%xmm6 401150: divss %xmm1,%xmm6 401154: mulss %xmm6,%xmm7 401158: comiss 0x0(%ebp),%xmm6 40115c: mulss %xmm6,%xmm5 401160: addss 0x4(%esp),%xmm7 -- Summary: runtime performance regression in floating point heavy code, x86/SSE Product: gcc Version: 4.0.0 Status: UNCONFIRMED Severity: normal Priority: P2 Component: rtl-optimization AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: tbptbp at gmail dot com CC: gcc-bugs at gcc dot gnu dot org GCC host triplet: cygwin http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19240
next reply other threads:[~2005-01-03 13:13 UTC|newest] Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top 2005-01-03 13:13 tbptbp at gmail dot com [this message] 2005-01-03 13:14 ` [Bug rtl-optimization/19240] " tbptbp at gmail dot com 2005-01-03 15:06 ` [Bug target/19240] [4.0 Regression] " pinskia at gcc dot gnu dot org 2005-01-03 16:27 ` uros at kss-loka dot si 2005-01-03 20:39 ` rth at gcc dot gnu dot org 2005-01-04 10:41 ` cvs-commit at gcc dot gnu dot org 2005-01-04 15:43 ` pinskia at gcc dot gnu dot org
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