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[LV] Transform truncations of non-primary induction variables

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The vectorizer tries to replace truncations of induction variables with new
induction variables having the smaller type. After r295063, this optimization
was applied to all integer induction variables, including non-primary ones.
When optimizing the truncation of a non-primary induction variable, we still
need to transform the new induction so that it has the correct start value.
This should fix PR32419.

Reference: https://bugs.llvm.org/show_bug.cgi?id=32419
llvm-svn: 298882
This commit is contained in:
Matthew Simpson
2017-03-27 20:07:38 +00:00
parent 6ebeb7041e
commit b8ff4a4a70
2 changed files with 55 additions and 11 deletions
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21
llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
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@@ -2521,22 +2521,21 @@ void InnerLoopVectorizer::widenIntOrFpInduction(PHINode *IV, TruncInst *Trunc) {
// induction variable and step. Otherwise, derive these values from the
// induction descriptor.
if (!VectorizedIV || NeedsScalarIV) {
ScalarIV = Induction;
if (IV != OldInduction) {
ScalarIV = IV->getType()->isIntegerTy()
? Builder.CreateSExtOrTrunc(Induction, IV->getType())
: Builder.CreateCast(Instruction::SIToFP, Induction,
IV->getType());
ScalarIV = ID.transform(Builder, ScalarIV, PSE.getSE(), DL);
ScalarIV->setName("offset.idx");
}
if (Trunc) {
auto *TruncType = cast<IntegerType>(Trunc->getType());
assert(Step->getType()->isIntegerTy() &&
"Truncation requires an integer step");
ScalarIV = Builder.CreateCast(Instruction::Trunc, Induction, TruncType);
ScalarIV = Builder.CreateTrunc(ScalarIV, TruncType);
Step = Builder.CreateTrunc(Step, TruncType);
} else {
ScalarIV = Induction;
if (IV != OldInduction) {
ScalarIV = IV->getType()->isIntegerTy()
? Builder.CreateSExtOrTrunc(ScalarIV, IV->getType())
: Builder.CreateCast(Instruction::SIToFP, Induction,
IV->getType());
ScalarIV = ID.transform(Builder, ScalarIV, PSE.getSE(), DL);
ScalarIV->setName("offset.idx");
}
}
}