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From: "vincenzo.innocente at cern dot ch" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug libgomp/58482] New: gomp4: user defined reduction produce wrong result Date: Fri, 20 Sep 2013 10:52:00 -0000 [thread overview] Message-ID: <bug-58482-4@http.gcc.gnu.org/bugzilla/> (raw) http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58482 Bug ID: 58482 Summary: gomp4: user defined reduction produce wrong result Product: gcc Version: 4.9.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: libgomp Assignee: unassigned at gcc dot gnu.org Reporter: vincenzo.innocente at cern dot ch CC: jakub at gcc dot gnu.org I acknowledge that my understanding of "omp declare" is still limited. Still the example below produces different result with and w/o -fopenmp gcc version 4.9.0 20130919 (experimental) [gomp-4_0-branch revision 202766] (GCC) pb-d-128-141-131-94:vectorize innocent$ c++ -std=c++11 ured_omp4.cpp -O -ftree-vectorizer-verbose=1; ./a.out 523776,-523776 pb-d-128-141-131-94:vectorize innocent$ c++ -std=c++11 ured_omp4.cpp -O -ftree-vectorizer-verbose=1 -fopenmp; ./a.out ured_omp4.cpp:26:8: note: loop turned into non-loop; it never loops ured_omp4.cpp:26:8: note: loop turned into non-loop; it never loops 523776,523776 cat ured_omp4.cpp #define Type float struct TwoInt { Type a=0; Type b=0; #pragma omp declare simd TwoInt & operator+=(TwoInt rh) { a+=rh.a; b-=rh.b; } #pragma omp declare simd TwoInt & add(TwoInt rh) { a+=rh.a; b-=rh.b; return *this; } }; #pragma omp declare reduction (foo:struct TwoInt: omp_out.add(omp_in)) TwoInt sum(Type const * q, int NN) { TwoInt s; #pragma omp simd reduction(foo:s) for (int i=0;i<NN;++i) { TwoInt l; l.a=q[i]; l.b = q[i]; s.add(l); } return s; } #include<iostream> int main() { constexpr int NN=1024; Type q[NN]; Type a=0; for (auto & e: q) e=a++; auto s = sum(q,NN); std::cout << s.a << "," << s.b << std::endl; return 0; }
next reply other threads:[~2013-09-20 10:52 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2013-09-20 10:52 vincenzo.innocente at cern dot ch [this message] 2013-09-20 11:16 ` [Bug libgomp/58482] " jakub at gcc dot gnu.org 2013-09-20 13:28 ` jakub at gcc dot gnu.org 2013-09-21 15:47 ` vincenzo.innocente at cern dot ch 2013-09-21 19:04 ` jakub at gcc dot gnu.org 2013-09-26 7:58 ` jakub at gcc dot gnu.org
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