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author | Arnold Schwaighofer <aschwaighofer@apple.com> | 2013-10-07 21:05:43 +0000 |
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committer | Arnold Schwaighofer <aschwaighofer@apple.com> | 2013-10-07 21:05:43 +0000 |
commit | 1ee3c0008be6f7012aa69f7a73a2819300bdf23f (patch) | |
tree | 6603eb4dc1458fae0bd918409ef74e8e363cc168 /lib/Transforms/Vectorize | |
parent | 42be15fcbeedaa67c4b5f4b19eb273749ae36465 (diff) | |
download | llvm-1ee3c0008be6f7012aa69f7a73a2819300bdf23f.tar.gz llvm-1ee3c0008be6f7012aa69f7a73a2819300bdf23f.tar.bz2 llvm-1ee3c0008be6f7012aa69f7a73a2819300bdf23f.tar.xz |
LoopVectorize: External uses must use the last value in a reduction cycle
Otherwise, we don't perform operations that would have been performed on
the scalar version.
Fixes PR17498.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192133 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Transforms/Vectorize')
-rw-r--r-- | lib/Transforms/Vectorize/LoopVectorize.cpp | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/lib/Transforms/Vectorize/LoopVectorize.cpp b/lib/Transforms/Vectorize/LoopVectorize.cpp index a71df08aba..415f86e893 100644 --- a/lib/Transforms/Vectorize/LoopVectorize.cpp +++ b/lib/Transforms/Vectorize/LoopVectorize.cpp @@ -4015,6 +4015,12 @@ bool LoopVectorizationLegality::AddReductionVar(PHINode *Phi, if (ExitInstruction != 0 || Cur == Phi) return false; + // The instruction used by an outside user must be the last instruction + // before we feed back to the reduction phi. Otherwise, we loose VF-1 + // operations on the value. + if (std::find(Phi->op_begin(), Phi->op_end(), Cur) == Phi->op_end()) + return false; + ExitInstruction = Cur; continue; } |