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-rw-r--r--llvm/include/llvm/Analysis/ConstantFolding.h6
-rw-r--r--llvm/include/llvm/Analysis/InstructionSimplify.h8
-rw-r--r--llvm/lib/Analysis/InstructionSimplify.cpp51
-rw-r--r--llvm/test/Transforms/InstSimplify/shufflevector.ll26
4 files changed, 85 insertions, 6 deletions
diff --git a/llvm/include/llvm/Analysis/ConstantFolding.h b/llvm/include/llvm/Analysis/ConstantFolding.h
index 517842c8b0d..ff6ca195915 100644
--- a/llvm/include/llvm/Analysis/ConstantFolding.h
+++ b/llvm/include/llvm/Analysis/ConstantFolding.h
@@ -100,6 +100,12 @@ Constant *ConstantFoldExtractValueInstruction(Constant *Agg,
/// successful; if not, null is returned.
Constant *ConstantFoldExtractElementInstruction(Constant *Val, Constant *Idx);
+/// \brief Attempt to constant fold a shufflevector instruction with the
+/// specified operands and indices. The constant result is returned if
+/// successful; if not, null is returned.
+Constant *ConstantFoldShuffleVectorInstruction(Constant *V1, Constant *V2,
+ Constant *Mask);
+
/// ConstantFoldLoadFromConstPtr - Return the value that a load from C would
/// produce if it is constant and determinable. If this is not determinable,
/// return null.
diff --git a/llvm/include/llvm/Analysis/InstructionSimplify.h b/llvm/include/llvm/Analysis/InstructionSimplify.h
index e4ffa1c0362..b829e995db0 100644
--- a/llvm/include/llvm/Analysis/InstructionSimplify.h
+++ b/llvm/include/llvm/Analysis/InstructionSimplify.h
@@ -247,6 +247,14 @@ namespace llvm {
AssumptionCache *AC = nullptr,
const Instruction *CxtI = nullptr);
+ /// Given operands for a ShuffleVectorInst, fold the result or return null.
+ Value *SimplifyShuffleVectorInst(Value *Op0, Value *Op1, Constant *Mask,
+ Type *RetTy, const DataLayout &DL,
+ const TargetLibraryInfo *TLI = nullptr,
+ const DominatorTree *DT = nullptr,
+ AssumptionCache *AC = nullptr,
+ const Instruction *CxtI = nullptr);
+
//=== Helper functions for higher up the class hierarchy.
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 6294d195cea..5cb93df7395 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -4081,6 +4081,50 @@ Value *llvm::SimplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty,
RecursionLimit);
}
+static Value *SimplifyShuffleVectorInst(Value *Op0, Value *Op1, Constant *Mask,
+ Type *RetTy, const Query &Q,
+ unsigned MaxRecurse) {
+ unsigned MaskNumElts = Mask->getType()->getVectorNumElements();
+ unsigned InVecNumElts = Op0->getType()->getVectorNumElements();
+
+ auto *Op0Const = dyn_cast<Constant>(Op0);
+ auto *Op1Const = dyn_cast<Constant>(Op1);
+
+ // If all operands are constant, constant fold the shuffle.
+ if (Op0Const && Op1Const)
+ return ConstantFoldShuffleVectorInstruction(Op0Const, Op1Const, Mask);
+
+ // If only one of the operands is constant, constant fold the shuffle if the
+ // mask does not select elements from the variable operand.
+ bool MaskSelects0 = false, MaskSelects1 = false;
+ for (unsigned i = 0; i != MaskNumElts; ++i) {
+ int Idx = ShuffleVectorInst::getMaskValue(Mask, i);
+ if (Idx == -1)
+ continue;
+ if ((unsigned)Idx < InVecNumElts)
+ MaskSelects0 = true;
+ else
+ MaskSelects1 = true;
+ }
+ if (!MaskSelects0 && Op1Const)
+ return ConstantFoldShuffleVectorInstruction(UndefValue::get(Op0->getType()),
+ Op1Const, Mask);
+ if (!MaskSelects1 && Op0Const)
+ return ConstantFoldShuffleVectorInstruction(
+ Op0Const, UndefValue::get(Op0->getType()), Mask);
+
+ return nullptr;
+}
+
+/// Given operands for a ShuffleVectorInst, fold the result or return null.
+Value *llvm::SimplifyShuffleVectorInst(
+ Value *Op0, Value *Op1, Constant *Mask, Type *RetTy,
+ const DataLayout &DL, const TargetLibraryInfo *TLI, const DominatorTree *DT,
+ AssumptionCache *AC, const Instruction *CxtI) {
+ return ::SimplifyShuffleVectorInst(
+ Op0, Op1, Mask, RetTy, Query(DL, TLI, DT, AC, CxtI), RecursionLimit);
+}
+
//=== Helper functions for higher up the class hierarchy.
/// Given operands for a BinaryOperator, see if we can fold the result.
@@ -4569,6 +4613,13 @@ Value *llvm::SimplifyInstruction(Instruction *I, const DataLayout &DL,
EEI->getVectorOperand(), EEI->getIndexOperand(), DL, TLI, DT, AC, I);
break;
}
+ case Instruction::ShuffleVector: {
+ auto *SVI = cast<ShuffleVectorInst>(I);
+ Result = SimplifyShuffleVectorInst(SVI->getOperand(0), SVI->getOperand(1),
+ SVI->getMask(), SVI->getType(), DL, TLI,
+ DT, AC, I);
+ break;
+ }
case Instruction::PHI:
Result = SimplifyPHINode(cast<PHINode>(I), Query(DL, TLI, DT, AC, I));
break;
diff --git a/llvm/test/Transforms/InstSimplify/shufflevector.ll b/llvm/test/Transforms/InstSimplify/shufflevector.ll
index 4a9c0dfb234..4b6580118fc 100644
--- a/llvm/test/Transforms/InstSimplify/shufflevector.ll
+++ b/llvm/test/Transforms/InstSimplify/shufflevector.ll
@@ -3,13 +3,29 @@
define <4 x i32> @const_folding(<4 x i32> %x) {
; CHECK-LABEL: @const_folding(
-; CHECK-NEXT: [[SHUF:%.*]] = shufflevector <4 x i32> [[X:%.*]], <4 x i32> zeroinitializer, <4 x i32> <i32 5, i32 4, i32 5, i32 4>
-; CHECK-NEXT: ret <4 x i32> [[SHUF]]
+; CHECK-NEXT: ret <4 x i32> zeroinitializer
;
%shuf = shufflevector <4 x i32> %x, <4 x i32> zeroinitializer, <4 x i32> <i32 5, i32 4, i32 5, i32 4>
ret <4 x i32> %shuf
}
+define <4 x i32> @const_folding1(<4 x i32> %x) {
+; CHECK-LABEL: @const_folding1(
+; CHECK-NEXT: ret <4 x i32> <i32 5, i32 5, i32 5, i32 5>
+;
+ %shuf = shufflevector <4 x i32> <i32 5, i32 4, i32 5, i32 4>, <4 x i32> %x, <4 x i32> zeroinitializer
+ ret <4 x i32> %shuf
+}
+
+define <4 x i32> @const_folding_negative(<3 x i32> %x) {
+; CHECK-LABEL: @const_folding_negative(
+; CHECK-NEXT: [[SHUF:%.*]] = shufflevector <3 x i32> [[X:%.*]], <3 x i32> zeroinitializer, <4 x i32> <i32 2, i32 4, i32 5, i32 4>
+; CHECK-NEXT: ret <4 x i32> [[SHUF]]
+;
+ %shuf = shufflevector <3 x i32> %x, <3 x i32> zeroinitializer, <4 x i32> <i32 2, i32 4, i32 5, i32 4>
+ ret <4 x i32> %shuf
+}
+
define <4 x i32> @splat_operand(<4 x i32> %x) {
; CHECK-LABEL: @splat_operand(
; CHECK-NEXT: [[SPLAT:%.*]] = shufflevector <4 x i32> [[X:%.*]], <4 x i32> undef, <4 x i32> zeroinitializer
@@ -23,8 +39,7 @@ define <4 x i32> @splat_operand(<4 x i32> %x) {
define <4 x i32> @undef_mask(<4 x i32> %x) {
; CHECK-LABEL: @undef_mask(
-; CHECK-NEXT: [[SHUF:%.*]] = shufflevector <4 x i32> [[X:%.*]], <4 x i32> undef, <4 x i32> undef
-; CHECK-NEXT: ret <4 x i32> [[SHUF]]
+; CHECK-NEXT: ret <4 x i32> undef
;
%shuf = shufflevector <4 x i32> %x, <4 x i32> undef, <4 x i32> undef
ret <4 x i32> %shuf
@@ -59,8 +74,7 @@ define <4 x i32> @pseudo_identity_mask(<4 x i32> %x) {
define <4 x i32> @const_operand(<4 x i32> %x) {
; CHECK-LABEL: @const_operand(
-; CHECK-NEXT: [[SHUF:%.*]] = shufflevector <4 x i32> <i32 42, i32 43, i32 44, i32 45>, <4 x i32> [[X:%.*]], <4 x i32> <i32 0, i32 3, i32 2, i32 1>
-; CHECK-NEXT: ret <4 x i32> [[SHUF]]
+; CHECK-NEXT: ret <4 x i32> <i32 42, i32 45, i32 44, i32 43>
;
%shuf = shufflevector <4 x i32> <i32 42, i32 43, i32 44, i32 45>, <4 x i32> %x, <4 x i32> <i32 0, i32 3, i32 2, i32 1>
ret <4 x i32> %shuf
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