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* [Bug tree-optimization/61175] New: failing vectorization
@ 2014-05-13 13:20 vincenzo.innocente at cern dot ch
  2014-05-15  7:31 ` [Bug tree-optimization/61175] failing vectorization in case of "complex access pattern" vincenzo.innocente at cern dot ch
  0 siblings, 1 reply; 2+ messages in thread
From: vincenzo.innocente at cern dot ch @ 2014-05-13 13:20 UTC (permalink / raw)
  To: gcc-bugs

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;
   }
}


^ permalink raw reply	[flat|nested] 2+ messages in thread
* [Bug tree-optimization/61175] failing vectorization in case of  "complex access pattern"
  2014-05-13 13:20 [Bug tree-optimization/61175] New: failing vectorization vincenzo.innocente at cern dot ch
@ 2014-05-15  7:31 ` vincenzo.innocente at cern dot ch
  0 siblings, 0 replies; 2+ messages in thread
From: vincenzo.innocente at cern dot ch @ 2014-05-15  7:31 UTC (permalink / raw)
  To: gcc-bugs

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

--- Comment #1 from vincenzo Innocente <vincenzo.innocente at cern dot ch> ---
adding 
#pragma GCC ivdep
before the loop makes no difference


^ permalink raw reply	[flat|nested] 2+ messages in thread
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2014-05-13 13:20 [Bug tree-optimization/61175] New: failing vectorization vincenzo.innocente at cern dot ch
2014-05-15  7:31 ` [Bug tree-optimization/61175] failing vectorization in case of "complex access pattern" vincenzo.innocente at cern dot ch

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