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[NFC][InstCombine] Negator: add thin negate() wrapped before visit()

This commit is contained in:
Roman Lebedev 2020-06-17 19:52:48 +03:00
parent 2b85147337
commit c4166f3d84
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GPG Key ID: 083C3EBB4A1689E0
2 changed files with 32 additions and 24 deletions
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4
llvm/lib/Transforms/InstCombine/InstCombineInternal.h
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@ -1051,7 +1051,9 @@ class Negator final {
using Result = std::pair<ArrayRef<Instruction *> /*NewInstructions*/, using Result = std::pair<ArrayRef<Instruction *> /*NewInstructions*/,
Value * /*NegatedRoot*/>; Value * /*NegatedRoot*/>;
LLVM_NODISCARD Value *visit(Value *V, unsigned Depth); LLVM_NODISCARD Value *visitImpl(Value *V, unsigned Depth);
LLVM_NODISCARD Value *negate(Value *V, unsigned Depth);
/// Recurse depth-first and attempt to sink the negation. /// Recurse depth-first and attempt to sink the negation.
/// FIXME: use worklist? /// FIXME: use worklist?

52
llvm/lib/Transforms/InstCombine/InstCombineNegator.cpp
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@ -110,14 +110,7 @@ Negator::~Negator() {
// FIXME: can this be reworked into a worklist-based algorithm while preserving // FIXME: can this be reworked into a worklist-based algorithm while preserving
// the depth-first, early bailout traversal? // the depth-first, early bailout traversal?
LLVM_NODISCARD Value *Negator::visit(Value *V, unsigned Depth) { LLVM_NODISCARD Value *Negator::visitImpl(Value *V, unsigned Depth) {
NegatorMaxDepthVisited.updateMax(Depth);
++NegatorNumValuesVisited;
#if LLVM_ENABLE_STATS
++NumValuesVisitedInThisNegator;
#endif
// -(undef) -> undef. // -(undef) -> undef.
if (match(V, m_Undef())) if (match(V, m_Undef()))
return V; return V;
@ -245,7 +238,8 @@ LLVM_NODISCARD Value *Negator::visit(Value *V, unsigned Depth) {
auto *PHI = cast<PHINode>(I); auto *PHI = cast<PHINode>(I);
SmallVector<Value *, 4> NegatedIncomingValues(PHI->getNumOperands()); SmallVector<Value *, 4> NegatedIncomingValues(PHI->getNumOperands());
for (auto I : zip(PHI->incoming_values(), NegatedIncomingValues)) { for (auto I : zip(PHI->incoming_values(), NegatedIncomingValues)) {
if (!(std::get<1>(I) = visit(std::get<0>(I), Depth + 1))) // Early return. if (!(std::get<1>(I) =
negate(std::get<0>(I), Depth + 1))) // Early return.
return nullptr; return nullptr;
} }
// All incoming values are indeed negatible. Create negated PHI node. // All incoming values are indeed negatible. Create negated PHI node.
@ -272,10 +266,10 @@ LLVM_NODISCARD Value *Negator::visit(Value *V, unsigned Depth) {
} }
} }
// `select` is negatible if both hands of `select` are negatible. // `select` is negatible if both hands of `select` are negatible.
Value *NegOp1 = visit(I->getOperand(1), Depth + 1); Value *NegOp1 = negate(I->getOperand(1), Depth + 1);
if (!NegOp1) // Early return. if (!NegOp1) // Early return.
return nullptr; return nullptr;
Value *NegOp2 = visit(I->getOperand(2), Depth + 1); Value *NegOp2 = negate(I->getOperand(2), Depth + 1);
if (!NegOp2) if (!NegOp2)
return nullptr; return nullptr;
// Do preserve the metadata! // Do preserve the metadata!
@ -285,10 +279,10 @@ LLVM_NODISCARD Value *Negator::visit(Value *V, unsigned Depth) {
case Instruction::ShuffleVector: { case Instruction::ShuffleVector: {
// `shufflevector` is negatible if both operands are negatible. // `shufflevector` is negatible if both operands are negatible.
auto *Shuf = cast<ShuffleVectorInst>(I); auto *Shuf = cast<ShuffleVectorInst>(I);
Value *NegOp0 = visit(I->getOperand(0), Depth + 1); Value *NegOp0 = negate(I->getOperand(0), Depth + 1);
if (!NegOp0) // Early return. if (!NegOp0) // Early return.
return nullptr; return nullptr;
Value *NegOp1 = visit(I->getOperand(1), Depth + 1); Value *NegOp1 = negate(I->getOperand(1), Depth + 1);
if (!NegOp1) if (!NegOp1)
return nullptr; return nullptr;
return Builder.CreateShuffleVector(NegOp0, NegOp1, Shuf->getShuffleMask(), return Builder.CreateShuffleVector(NegOp0, NegOp1, Shuf->getShuffleMask(),
@ -297,7 +291,7 @@ LLVM_NODISCARD Value *Negator::visit(Value *V, unsigned Depth) {
case Instruction::ExtractElement: { case Instruction::ExtractElement: {
// `extractelement` is negatible if source operand is negatible. // `extractelement` is negatible if source operand is negatible.
auto *EEI = cast<ExtractElementInst>(I); auto *EEI = cast<ExtractElementInst>(I);
Value *NegVector = visit(EEI->getVectorOperand(), Depth + 1); Value *NegVector = negate(EEI->getVectorOperand(), Depth + 1);
if (!NegVector) // Early return. if (!NegVector) // Early return.
return nullptr; return nullptr;
return Builder.CreateExtractElement(NegVector, EEI->getIndexOperand(), return Builder.CreateExtractElement(NegVector, EEI->getIndexOperand(),
@ -307,10 +301,10 @@ LLVM_NODISCARD Value *Negator::visit(Value *V, unsigned Depth) {
// `insertelement` is negatible if both the source vector and // `insertelement` is negatible if both the source vector and
// element-to-be-inserted are negatible. // element-to-be-inserted are negatible.
auto *IEI = cast<InsertElementInst>(I); auto *IEI = cast<InsertElementInst>(I);
Value *NegVector = visit(IEI->getOperand(0), Depth + 1); Value *NegVector = negate(IEI->getOperand(0), Depth + 1);
if (!NegVector) // Early return. if (!NegVector) // Early return.
return nullptr; return nullptr;
Value *NegNewElt = visit(IEI->getOperand(1), Depth + 1); Value *NegNewElt = negate(IEI->getOperand(1), Depth + 1);
if (!NegNewElt) // Early return. if (!NegNewElt) // Early return.
return nullptr; return nullptr;
return Builder.CreateInsertElement(NegVector, NegNewElt, IEI->getOperand(2), return Builder.CreateInsertElement(NegVector, NegNewElt, IEI->getOperand(2),
@ -318,14 +312,14 @@ LLVM_NODISCARD Value *Negator::visit(Value *V, unsigned Depth) {
} }
case Instruction::Trunc: { case Instruction::Trunc: {
// `trunc` is negatible if its operand is negatible. // `trunc` is negatible if its operand is negatible.
Value *NegOp = visit(I->getOperand(0), Depth + 1); Value *NegOp = negate(I->getOperand(0), Depth + 1);
if (!NegOp) // Early return. if (!NegOp) // Early return.
return nullptr; return nullptr;
return Builder.CreateTrunc(NegOp, I->getType(), I->getName() + ".neg"); return Builder.CreateTrunc(NegOp, I->getType(), I->getName() + ".neg");
} }
case Instruction::Shl: { case Instruction::Shl: {
// `shl` is negatible if the first operand is negatible. // `shl` is negatible if the first operand is negatible.
Value *NegOp0 = visit(I->getOperand(0), Depth + 1); Value *NegOp0 = negate(I->getOperand(0), Depth + 1);
if (!NegOp0) // Early return. if (!NegOp0) // Early return.
return nullptr; return nullptr;
return Builder.CreateShl(NegOp0, I->getOperand(1), I->getName() + ".neg"); return Builder.CreateShl(NegOp0, I->getOperand(1), I->getName() + ".neg");
@ -342,10 +336,10 @@ LLVM_NODISCARD Value *Negator::visit(Value *V, unsigned Depth) {
LLVM_FALLTHROUGH; LLVM_FALLTHROUGH;
case Instruction::Add: { case Instruction::Add: {
// `add` is negatible if both of its operands are negatible. // `add` is negatible if both of its operands are negatible.
Value *NegOp0 = visit(I->getOperand(0), Depth + 1); Value *NegOp0 = negate(I->getOperand(0), Depth + 1);
if (!NegOp0) // Early return. if (!NegOp0) // Early return.
return nullptr; return nullptr;
Value *NegOp1 = visit(I->getOperand(1), Depth + 1); Value *NegOp1 = negate(I->getOperand(1), Depth + 1);
if (!NegOp1) if (!NegOp1)
return nullptr; return nullptr;
return Builder.CreateAdd(NegOp0, NegOp1, I->getName() + ".neg"); return Builder.CreateAdd(NegOp0, NegOp1, I->getName() + ".neg");
@ -364,10 +358,10 @@ LLVM_NODISCARD Value *Negator::visit(Value *V, unsigned Depth) {
Value *NegatedOp, *OtherOp; Value *NegatedOp, *OtherOp;
// First try the second operand, in case it's a constant it will be best to // First try the second operand, in case it's a constant it will be best to
// just invert it instead of sinking the `neg` deeper. // just invert it instead of sinking the `neg` deeper.
if (Value *NegOp1 = visit(I->getOperand(1), Depth + 1)) { if (Value *NegOp1 = negate(I->getOperand(1), Depth + 1)) {
NegatedOp = NegOp1; NegatedOp = NegOp1;
OtherOp = I->getOperand(0); OtherOp = I->getOperand(0);
} else if (Value *NegOp0 = visit(I->getOperand(0), Depth + 1)) { } else if (Value *NegOp0 = negate(I->getOperand(0), Depth + 1)) {
NegatedOp = NegOp0; NegatedOp = NegOp0;
OtherOp = I->getOperand(1); OtherOp = I->getOperand(1);
} else } else
@ -382,8 +376,20 @@ LLVM_NODISCARD Value *Negator::visit(Value *V, unsigned Depth) {
llvm_unreachable("Can't get here. We always return from switch."); llvm_unreachable("Can't get here. We always return from switch.");
} }
LLVM_NODISCARD Value *Negator::negate(Value *V, unsigned Depth) {
NegatorMaxDepthVisited.updateMax(Depth);
++NegatorNumValuesVisited;
#if LLVM_ENABLE_STATS
++NumValuesVisitedInThisNegator;
#endif
// Try negating the value.
return visitImpl(V, Depth);
}
LLVM_NODISCARD Optional<Negator::Result> Negator::run(Value *Root) { LLVM_NODISCARD Optional<Negator::Result> Negator::run(Value *Root) {
Value *Negated = visit(Root, /*Depth=*/0); Value *Negated = negate(Root, /*Depth=*/0);
if (!Negated) { if (!Negated) {
// We must cleanup newly-inserted instructions, to avoid any potential // We must cleanup newly-inserted instructions, to avoid any potential
// endless combine looping. // endless combine looping.