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From: "vincenzo.innocente at cern dot ch" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/61194] New: vectorization failed with "bit-precision arithmetic not supported" even if conversion to int is requested
Date: Thu, 15 May 2014 12:09:00 -0000
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X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 4.9.0
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X-Bugzilla-Who: vincenzo.innocente at cern dot ch
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61194

            Bug ID: 61194
           Summary: vectorization failed with "bit-precision arithmetic
                    not supported" even if conversion to int is requested
           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

z[i] = ( (x[i]>0) & (w[i]<0)) ? z[i] : y[i];
produces

bit-precision arithmetic not supported.
note: not vectorized: relevant stmt not supported: _6 = _5 > 0.0;

while integer bitwise operators are vectorized at will
 z[i] = ( k[i] & j[i] ) ? z[i] : y[i];

I tried to force conversion to int in many ways (see below) such as 
z[i] = ( int(x[i]>0) & int(w[i]<0)) ? z[i] : y[i];
succeeding only with the quite expensive
z[i] = (2==(int(x[i]>0) + int(w[i]<0))) ? z[i] : y[i];

is there a way to force gcc to use integer w/o using arithmetic operators?

c++ -Ofast -Wall -fno-tree-slp-vectorize -ftree-loop-if-convert-stores -S
cond.cc -msse4.2 -fopt-info-vec -fno-tree-slp-vectorize  -fopenmp
cat cond.cc
float x[1024];
float y[1024];
float z[1024];
float w[1024];

int k[1024];
int j[1024];


void bar() {
  for (int i=0; i<1024; ++i)
    z[i] = ( (x[i]>0) & (w[i]<0)) ? z[i] : y[i];
}


void barMP() {
#pragma omp simd
  for (int i=0; i<1024; ++i)
    z[i] = ( int(x[i]>0) & int(w[i]<0)) ? z[i] : y[i];
}


void barInt() {
  for (int i=0; i<1024; ++i)
    z[i] = ( int(x[i]>0) & int(w[i]<0)) ? z[i] : y[i];
}

void barInt0() {
  for (int i=0; i<1024; ++i)
    z[i] = ( (0+int(x[i]>0)) & (0+int(w[i]<0)) ) ? z[i] : y[i];
}


void barPlus() {
  for (int i=0; i<1024; ++i)
    z[i] = (2==(int(x[i]>0) + int(w[i]<0))) ? z[i] : y[i];
}


void foo() {
  for (int i=0; i<1024; ++i)
    z[i] = ( k[i] & j[i] ) ? z[i] : y[i];
}


void foo2() {
  for (int i=0; i<1024; ++i) {
    k[i] = x[i]>0; j[i] = w[i]<0;
  }
}

void bar2() {
  for (int i=0; i<1024; ++i) {
    k[i] = x[i]>0; j[i] = w[i]<0;
    z[i] = ( k[i] & j[i]) ? z[i] : y[i];
 }
}