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[InstCombine] avoid crashing on shuffle shrinkage when input type is not same as result type 

llvm-svn: 297280
This commit is contained in:
Sanjay Patel 2017-03-08 15:02:23 +00:00
parent 9ef5778038
commit 62906af379
2 changed files with 15 additions and 1 deletions
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3
llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
View File

@ -470,7 +470,8 @@ static Instruction *shrinkSplatShuffle(TruncInst &Trunc,
InstCombiner::BuilderTy &Builder) {
auto *Shuf = dyn_cast<ShuffleVectorInst>(Trunc.getOperand(0));
if (Shuf && Shuf->hasOneUse() && isa<UndefValue>(Shuf->getOperand(1)) &&
Shuf->getMask()->getSplatValue()) {
Shuf->getMask()->getSplatValue() &&
Shuf->getType() == Shuf->getOperand(0)->getType()) {
// trunc (shuf X, Undef, SplatMask) --> shuf (trunc X), Undef, SplatMask
Constant *NarrowUndef = UndefValue::get(Trunc.getType());
Value *NarrowOp = Builder.CreateTrunc(Shuf->getOperand(0), Trunc.getType());

13
llvm/test/Transforms/InstCombine/trunc.ll
View File

@ -520,3 +520,16 @@ define <3 x i31> @wide_splat3(<3 x i33> %x) {
ret <3 x i31> %trunc
}
; TODO: The shuffle extends the length of the input vector. Should we shrink this?
define <8 x i8> @wide_lengthening_splat(<4 x i16> %v) {
; CHECK-LABEL: @wide_lengthening_splat(
; CHECK-NEXT: [[SHUF:%.*]] = shufflevector <4 x i16> %v, <4 x i16> undef, <8 x i32> zeroinitializer
; CHECK-NEXT: [[TR:%.*]] = trunc <8 x i16> [[SHUF]] to <8 x i8>
; CHECK-NEXT: ret <8 x i8> [[TR]]
;
%shuf = shufflevector <4 x i16> %v, <4 x i16> %v, <8 x i32> zeroinitializer
%tr = trunc <8 x i16> %shuf to <8 x i8>
ret <8 x i8> %tr
}