[Bug tree-optimization/61247] New: vectorization fails if conversion from unsigned int to signed int is involved

[vincenzo.innocente at cern dot ch]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61247

            Bug ID: 61247
           Summary: vectorization fails if conversion from unsigned int to
                    signed int is involved
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: vincenzo.innocente at cern dot ch

in the following example
cat uintLoop.cc
unsigned int N;
float * a, *b, *c;

using Ind = /*unsigned*/ int;
inline
float & val(float * x, Ind i) { return x[i];}
inline
float const & val(float const * x, Ind i) { return x[i];}

void foo() {
#pragma GCC ivdep
  for (auto i=0U; i<N; ++i)
    val(a,i) = val(b,i)*val(c,i);
}


using Ind = /*unsigned*/ int;
does not vectorize with
c++ -std=c++1y -Ofast -Wall -fopt-info-vec-missed -fno-tree-slp-vectorize
-march=nehalem -S uintLoop.cc
uintLoop.cc:12:17: note: not vectorized: not suitable for gather load _8 =
*_17;

uintLoop.cc:12:17: note: bad data references.


using Ind = unsigned int;
vectorize fine


minor, just annoying