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List:       gcc-bugs
Subject:    [Bug tree-optimization/70482] New: Opimization opportunity to vectorize basic block for -mavx target
From:       "ysrumyan at gmail dot com" <gcc-bugzilla () gcc ! gnu ! org>
Date:       2016-03-31 16:15:49
Message-ID: bug-70482-4 () http ! gcc ! gnu ! org/bugzilla/
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70482

            Bug ID: 70482
           Summary: Opimization opportunity to vectorize basic block for
                    -mavx target.
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ysrumyan at gmail dot com
  Target Milestone: ---

If we compile bb-slp-pattern-1.c from gcc.dg/vect suite with -mavx pattern
vectorization won't happen since AVX has very poor support for 256-bit integer
arithmetic. Particularly, widen-mult pattern is recognized but it is not
supported for 256-bit vectors.
Test is failed for native compiler build on AVX machine. The most simple
decision is to use the same scheme as for loop vectorization by decreasing
vector size from 256-bit to 128-bit.=
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