[Bug tree-optimization/61175] New: failing vectorization

vincenzo.innocente at cern dot ch gcc-bugzilla@gcc.gnu.org
Tue May 13 13:20:00 GMT 2014


https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61175

            Bug ID: 61175
           Summary: failing vectorization
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: vincenzo.innocente at cern dot ch

of these three function only "oneOk"  vectorize.

float px[1024];
float vx[1024];
unsigned int N=1024;


void one(unsigned int i) {
   for (auto j=i+1; j<N; ++j) {
      auto ax = px[j]-px[i];
      vx[i]-=ax;
      vx[j]+=ax;
   }
}

void oneOK(unsigned int k) {
  auto tmp = vx[k];
   for (auto j=0; j<k-1; ++j) {
      auto ax = px[j]-px[k];
      tmp-=ax;
      vx[j]+=ax;
   }
   vx[k]=tmp;
}


void oneNope(unsigned int k) {
   for (auto j=0; j<k-1; ++j) {
      auto ax = px[j]-px[k];
      vx[k]-=ax;
      vx[j]+=ax;
   }
}



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