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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/108752] New: word_mode vectorization is
 pessimized by hard limit on nunits
Date: Fri, 10 Feb 2023 11:24:30 +0000
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X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 13.0
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D108752

            Bug ID: 108752
           Summary: word_mode vectorization is pessimized by hard limit on
                    nunits
           Product: gcc
           Version: 13.0
            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: ---

r13-5771-gdc87e1391c55c6 re-introduced a hard nunits limit to the vectorizer
when using emulated vectors (aka word_mode vectorization).  That's because
this feature relies on vector lowering to implement plus, minus and negate
with bit operations and that has such limit in place for when dealing with
user written code that didn't have any cost modeling applied.

The fix is to emit supported operations from the vectorizer.=