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From: "yuri at tsoft dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c/25500] New: REGREGRESSION: SSE2 vectorized code is many times slower on 4.x.x than on 3.4.4 Date: Tue, 20 Dec 2005 05:25:00 -0000 [thread overview] Message-ID: <bug-25500-6649@http.gcc.gnu.org/bugzilla/> (raw) The following testcase when compiled with 'g++ -O3 -msse3 -o testcase testcase.C' finishes in 0m0.277s if compiled with gcc-3.4.4 and in 0m44.843s if compiled with gcc-4.0.2 (similar on all 4.x.x). Yuri ----------------------------------------------------------------------- typedef float __v2df __attribute__ ((__vector_size__ (16))); typedef __v2df __m128; static __inline __m128 _mm_sub_pd (__m128 __A, __m128 __B) { return (__m128)__builtin_ia32_subps ((__v2df)__A, (__v2df)__B); } static __inline __m128 _mm_add_pd (__m128 __A, __m128 __B) { return (__m128)__builtin_ia32_addps ((__v2df)__A, (__v2df)__B); } static __inline __m128 _mm_setr_ps (float __Z, float __Y, float __X, float __W) { return __extension__ (__m128)(__v2df){ __Z, __Y, __X, __W }; } struct FF { __m128 d; __inline FF() { } __inline FF(__m128 new_d) : d(new_d) { } __inline FF(float f) : d(_mm_setr_ps(f, f, f, f)) { } __inline FF operator+(FF other) { return (FF(_mm_add_pd(d,other.d))); } __inline FF operator-(FF other) { return (FF(_mm_sub_pd(d,other.d))); } }; float f[1024*1024]; int main() { int i; for (i = 0; i < 1024*1024; i++) { f[i] = 1.f/(1024*1024 + 10 - i); } FF total(0.f); for (int rpt = 0; rpt < 1000; rpt++) { FF p1(0.f), p2(0.), c; __m128 *pf = (__m128*)f; for (i = 0; i < 1024*1024/4; i++) { FF c(*pf++); total = total + c - p2 + p1; p1 = p2; p2 = c; } } } -- Summary: REGREGRESSION: SSE2 vectorized code is many times slower on 4.x.x than on 3.4.4 Product: gcc Version: 4.0.2 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: yuri at tsoft dot com http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25500
next reply other threads:[~2005-12-20 5:25 UTC|newest] Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top 2005-12-20 5:25 yuri at tsoft dot com [this message] 2005-12-20 5:34 ` [Bug c/25500] " yuri at tsoft dot com 2005-12-20 5:55 ` [Bug target/25500] " pinskia at gcc dot gnu dot org 2005-12-20 6:01 ` yuri at tsoft dot com 2005-12-20 6:03 ` yuri at tsoft dot com 2005-12-20 6:19 ` yuri at tsoft dot com 2005-12-20 6:33 ` pinskia at gcc dot gnu dot org 2005-12-20 6:36 ` pinskia at gcc dot gnu dot org 2005-12-20 6:51 ` yuri at tsoft dot com 2005-12-20 6:55 ` pinskia at gcc dot gnu dot org 2005-12-20 7:40 ` yuri at tsoft dot com 2005-12-25 1:02 ` [Bug target/25500] [4.0/4.1/4.2 Regression]: " pinskia at gcc dot gnu dot org 2005-12-28 16:53 ` jakub at gcc dot gnu dot org 2006-01-15 22:13 ` [Bug target/25500] [4.0/4.1/4.2 Regression]: SSE2 vectorized code is " mmitchel at gcc dot gnu dot org 2006-02-24 0:31 ` mmitchel at gcc dot gnu dot org 2006-05-25 2:38 ` [Bug target/25500] [4.0/4.1/4.2 Regression]: SSE2 vectorized code is slower on 4.x.x than previous mmitchel at gcc dot gnu dot org 2006-07-05 9:50 ` pinskia at gcc dot gnu dot org 2006-08-07 7:55 ` bonzini at gnu dot org 2006-08-07 7:59 ` bonzini at gnu dot org 2006-08-07 15:36 ` pinskia at gcc dot gnu dot org 2006-08-17 8:16 ` bonzini at gnu dot org 2006-08-18 16:16 ` bonzini at gnu dot org 2006-11-12 8:07 ` [Bug target/25500] [4.0/4.1/4.2/4.3 " pinskia at gcc dot gnu dot org 2006-11-15 0:38 ` pinskia at gcc dot gnu dot org 2006-11-20 20:29 ` pinskia at gcc dot gnu dot org 2006-11-20 20:29 ` pinskia at gcc dot gnu dot org
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