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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/95960] New: GCC should re-vectorize vector
 code with larger VF
Date: Mon, 29 Jun 2020 12:09:28 +0000
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X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 11.0
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D95960

            Bug ID: 95960
           Summary: GCC should re-vectorize vector code with larger VF
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rguenth at gcc dot gnu.org
  Target Milestone: ---

For the following simple case GCC should vectorize it using AVX:

typedef double __attribute__((vector_size(16))) v2df;
double a[4];
double b[4];
void f()
{
  *(v2df *)&b[0] +=3D *(v2df *)&a[0];
  *(v2df *)&b[2] +=3D *(v2df *)&a[2];
}

Similar opportunities may exist for loops where also Neon -> SVE transforms
may be profitable.  Starting with BB vectorization might be easier since
you only need to consider SLP.=