Index: lib/Transforms/InstCombine/InstCombineVectorOps.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineVectorOps.cpp
+++ lib/Transforms/InstCombine/InstCombineVectorOps.cpp
@@ -352,6 +352,48 @@
return false;
}
+/// If we have insertion into a vector that is wider than the vector that we
+/// are extracting from, try to widen the source vector to allow a single
+/// shufflevector to replace one or more insert/extract pairs.
+static void replaceExtractElements(InsertElementInst *InsElt,
+ ExtractElementInst *ExtElt,
+ InstCombiner &IC) {
+ VectorType *InsVecType = InsElt->getType();
+ VectorType *ExtVecType = ExtElt->getVectorOperandType();
+ unsigned NumInsElts = InsVecType->getVectorNumElements();
+ unsigned NumExtElts = ExtVecType->getVectorNumElements();
+
+ // The inserted-to vector must be wider than the extracted-from vector.
+ if (InsVecType->getElementType() != ExtVecType->getElementType() ||
+ NumExtElts >= NumInsElts)
+ return;
+
+ // Create a shuffle mask to widen the extended-from vector using undefined
+ // values. The mask selects all of the values of the original vector followed
+ // by as many undefined values as needed to create a vector of the same length
+ // as the inserted-to vector.
+ SmallVector<Constant *, 16> ExtendMask;
+ IntegerType *IntType = Type::getInt32Ty(InsElt->getContext());
+ for (unsigned i = 0; i < NumExtElts; ++i)
+ ExtendMask.push_back(ConstantInt::get(IntType, i));
+ for (unsigned i = NumExtElts; i < NumInsElts; ++i)
+ ExtendMask.push_back(UndefValue::get(IntType));
+
+ Value *ExtVecOp = ExtElt->getVectorOperand();
+ auto *WideVec = new ShuffleVectorInst(ExtVecOp, UndefValue::get(ExtVecType),
+ ConstantVector::get(ExtendMask));
+
+ // Replace all extracts from the original narrow vector with extracts from
+ // the new wide vector.
+ WideVec->insertBefore(ExtElt);
+ for (User *U : ExtVecOp->users()) {
+ if (ExtractElementInst *OldExt = dyn_cast<ExtractElementInst>(U)) {
+ auto *NewExt = ExtractElementInst::Create(WideVec, OldExt->getOperand(1));
+ NewExt->insertAfter(WideVec);
+ IC.ReplaceInstUsesWith(*OldExt, NewExt);
+ }
+ }
+}
/// We are building a shuffle to create V, which is a sequence of insertelement,
/// extractelement pairs. If PermittedRHS is set, then we must either use it or
@@ -365,7 +407,8 @@
static ShuffleOps collectShuffleElements(Value *V,
SmallVectorImpl<Constant *> &Mask,
- Value *PermittedRHS) {
+ Value *PermittedRHS,
+ InstCombiner &IC) {
assert(V->getType()->isVectorTy() && "Invalid shuffle!");
unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
@@ -396,10 +439,14 @@
// otherwise we'd end up with a shuffle of three inputs.
if (EI->getOperand(0) == PermittedRHS || PermittedRHS == nullptr) {
Value *RHS = EI->getOperand(0);
- ShuffleOps LR = collectShuffleElements(VecOp, Mask, RHS);
+ ShuffleOps LR = collectShuffleElements(VecOp, Mask, RHS, IC);
assert(LR.second == nullptr || LR.second == RHS);
if (LR.first->getType() != RHS->getType()) {
+ // Although we are giving up for now, see if we can create extracts
+ // that match the inserts for another round of combining.
+ replaceExtractElements(IEI, EI, IC);
+
// We tried our best, but we can't find anything compatible with RHS
// further up the chain. Return a trivial shuffle.
for (unsigned i = 0; i < NumElts; ++i)
@@ -512,7 +559,7 @@
// (and any insertelements it points to), into one big shuffle.
if (!IE.hasOneUse() || !isa<InsertElementInst>(IE.user_back())) {
SmallVector<Constant*, 16> Mask;
- ShuffleOps LR = collectShuffleElements(&IE, Mask, nullptr);
+ ShuffleOps LR = collectShuffleElements(&IE, Mask, nullptr, *this);
// The proposed shuffle may be trivial, in which case we shouldn't
// perform the combine.
Index: test/Transforms/InstCombine/insert-extract-shuffle.ll
===================================================================
--- test/Transforms/InstCombine/insert-extract-shuffle.ll
+++ test/Transforms/InstCombine/insert-extract-shuffle.ll
@@ -26,8 +26,8 @@
define <2 x i64> @test_vcopyq_lane_p64(<2 x i64> %a, <1 x i64> %b) {
; CHECK-LABEL: @test_vcopyq_lane_p64
-; CHECK-NEXT: extractelement
-; CHECK-NEXT: insertelement
+; CHECK-NEXT: %[[WIDEVEC:.*]] = shufflevector <1 x i64> %b, <1 x i64> undef, <2 x i32> <i32 0, i32 undef>
+; CHECK-NEXT: shufflevector <2 x i64> %a, <2 x i64> %[[WIDEVEC]], <2 x i32> <i32 0, i32 2>
; CHECK-NEXT: ret <2 x i64> %res
%elt = extractelement <1 x i64> %b, i32 0
%res = insertelement <2 x i64> %a, i64 %elt, i32 1
@@ -38,10 +38,8 @@
define <4 x float> @widen_extract2(<4 x float> %ins, <2 x float> %ext) {
; CHECK-LABEL: @widen_extract2(
-; CHECK-NEXT: extractelement
-; CHECK-NEXT: extractelement
-; CHECK-NEXT: insertelement
-; CHECK-NEXT: insertelement
+; CHECK-NEXT: %[[WIDEVEC:.*]] = shufflevector <2 x float> %ext, <2 x float> undef, <4 x i32> <i32 0, i32 1, i32 undef, i32 undef>
+; CHECK-NEXT: shufflevector <4 x float> %ins, <4 x float> %[[WIDEVEC]], <4 x i32> <i32 0, i32 4, i32 2, i32 5>
; CHECK-NEXT: ret <4 x float> %i2
%e1 = extractelement <2 x float> %ext, i32 0
%e2 = extractelement <2 x float> %ext, i32 1
@@ -52,12 +50,8 @@
define <4 x float> @widen_extract3(<4 x float> %ins, <3 x float> %ext) {
; CHECK-LABEL: @widen_extract3(
-; CHECK-NEXT: extractelement
-; CHECK-NEXT: extractelement
-; CHECK-NEXT: extractelement
-; CHECK-NEXT: insertelement
-; CHECK-NEXT: insertelement
-; CHECK-NEXT: insertelement
+; CHECK-NEXT: %[[WIDEVEC:.*]] = shufflevector <3 x float> %ext, <3 x float> undef, <4 x i32> <i32 0, i32 1, i32 2, i32 undef>
+; CHECK-NEXT: shufflevector <4 x float> %ins, <4 x float> %[[WIDEVEC]], <4 x i32> <i32 6, i32 5, i32 4, i32 3>
; CHECK-NEXT: ret <4 x float> %i3
%e1 = extractelement <3 x float> %ext, i32 0
%e2 = extractelement <3 x float> %ext, i32 1
@@ -68,10 +62,10 @@
ret <4 x float> %i3
}
-define <8 x float> @too_wide(<8 x float> %ins, <2 x float> %ext) {
-; CHECK-LABEL: @too_wide(
-; CHECK-NEXT: extractelement
-; CHECK-NEXT: insertelement
+define <8 x float> @widen_extract4(<8 x float> %ins, <2 x float> %ext) {
+; CHECK-LABEL: @widen_extract4(
+; CHECK-NEXT: %[[WIDEVEC:.*]] = shufflevector <2 x float> %ext, <2 x float> undef, <8 x i32> <i32 0, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef>
+; CHECK-NEXT: shufflevector <8 x float> %ins, <8 x float> %[[WIDEVEC]], <8 x i32> <i32 0, i32 1, i32 8, i32 3, i32 4, i32 5, i32 6, i32 7>
; CHECK-NEXT: ret <8 x float> %i1
%e1 = extractelement <2 x float> %ext, i32 0
%i1 = insertelement <8 x float> %ins, float %e1, i32 2