#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/TargetTransformInfo.h"
+#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
"computations were sunk");
STATISTIC(NumExtsMoved, "Number of [s|z]ext instructions combined with loads");
STATISTIC(NumExtUses, "Number of uses of [s|z]ext instructions optimized");
+STATISTIC(NumAndsAdded,
+ "Number of and mask instructions added to form ext loads");
+STATISTIC(NumAndUses, "Number of uses of and mask instructions optimized");
STATISTIC(NumRetsDup, "Number of return instructions duplicated");
STATISTIC(NumDbgValueMoved, "Number of debug value instructions moved");
STATISTIC(NumSelectsExpanded, "Number of selects turned into branches");
bool optimizeCallInst(CallInst *CI, bool& ModifiedDT);
bool moveExtToFormExtLoad(Instruction *&I);
bool optimizeExtUses(Instruction *I);
+ bool optimizeLoadExt(LoadInst *I);
bool optimizeSelectInst(SelectInst *SI);
bool optimizeShuffleVectorInst(ShuffleVectorInst *SI);
+ bool optimizeSwitchInst(SwitchInst *CI);
bool optimizeExtractElementInst(Instruction *Inst);
bool dupRetToEnableTailCallOpts(BasicBlock *BB);
bool placeDbgValues(Function &F);
if (!OptSize && TLI && TLI->isSlowDivBypassed()) {
const DenseMap<unsigned int, unsigned int> &BypassWidths =
TLI->getBypassSlowDivWidths();
- for (Function::iterator I = F.begin(); I != F.end(); I++)
- EverMadeChange |= bypassSlowDivision(F, I, BypassWidths);
+ BasicBlock* BB = &*F.begin();
+ while (BB != nullptr) {
+ // bypassSlowDivision may create new BBs, but we don't want to reapply the
+ // optimization to those blocks.
+ BasicBlock* Next = BB->getNextNode();
+ EverMadeChange |= bypassSlowDivision(BB, BypassWidths);
+ BB = Next;
+ }
}
// Eliminate blocks that contain only PHI nodes and an
while (MadeChange) {
MadeChange = false;
for (Function::iterator I = F.begin(); I != F.end(); ) {
- BasicBlock *BB = I++;
+ BasicBlock *BB = &*I++;
bool ModifiedDTOnIteration = false;
MadeChange |= optimizeBlock(*BB, ModifiedDTOnIteration);
bool Changed = false;
// Scan all of the blocks in the function, except for the entry block.
for (Function::iterator I = std::next(F.begin()), E = F.end(); I != E;) {
- BasicBlock *BB = I++;
+ BasicBlock *BB = &*I++;
// If the destination block has a single pred, then this is a trivial
// edge, just collapse it.
BasicBlock *SinglePred = BB->getSinglePredecessor();
BB->moveBefore(&BB->getParent()->getEntryBlock());
// We have erased a block. Update the iterator.
- I = BB;
+ I = BB->getIterator();
}
}
return Changed;
bool MadeChange = false;
// Note that this intentionally skips the entry block.
for (Function::iterator I = std::next(F.begin()), E = F.end(); I != E;) {
- BasicBlock *BB = I++;
+ BasicBlock *BB = &*I++;
// If this block doesn't end with an uncond branch, ignore it.
BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator());
// If the instruction before the branch (skipping debug info) isn't a phi
// node, then other stuff is happening here.
- BasicBlock::iterator BBI = BI;
+ BasicBlock::iterator BBI = BI->getIterator();
if (BBI != BB->begin()) {
--BBI;
while (isa<DbgInfoIntrinsic>(BBI)) {
// Computes a map of base pointer relocation instructions to corresponding
// derived pointer relocation instructions given a vector of all relocate calls
static void computeBaseDerivedRelocateMap(
- const SmallVectorImpl<User *> &AllRelocateCalls,
- DenseMap<IntrinsicInst *, SmallVector<IntrinsicInst *, 2>> &
- RelocateInstMap) {
+ const SmallVectorImpl<GCRelocateInst *> &AllRelocateCalls,
+ DenseMap<GCRelocateInst *, SmallVector<GCRelocateInst *, 2>>
+ &RelocateInstMap) {
// Collect information in two maps: one primarily for locating the base object
// while filling the second map; the second map is the final structure holding
// a mapping between Base and corresponding Derived relocate calls
- DenseMap<std::pair<unsigned, unsigned>, IntrinsicInst *> RelocateIdxMap;
- for (auto &U : AllRelocateCalls) {
- GCRelocateOperands ThisRelocate(U);
- IntrinsicInst *I = cast<IntrinsicInst>(U);
- auto K = std::make_pair(ThisRelocate.getBasePtrIndex(),
- ThisRelocate.getDerivedPtrIndex());
- RelocateIdxMap.insert(std::make_pair(K, I));
+ DenseMap<std::pair<unsigned, unsigned>, GCRelocateInst *> RelocateIdxMap;
+ for (auto *ThisRelocate : AllRelocateCalls) {
+ auto K = std::make_pair(ThisRelocate->getBasePtrIndex(),
+ ThisRelocate->getDerivedPtrIndex());
+ RelocateIdxMap.insert(std::make_pair(K, ThisRelocate));
}
for (auto &Item : RelocateIdxMap) {
std::pair<unsigned, unsigned> Key = Item.first;
// Base relocation: nothing to insert
continue;
- IntrinsicInst *I = Item.second;
+ GCRelocateInst *I = Item.second;
auto BaseKey = std::make_pair(Key.first, Key.first);
// We're iterating over RelocateIdxMap so we cannot modify it.
// Takes a RelocatedBase (base pointer relocation instruction) and Targets to
// replace, computes a replacement, and affects it.
static bool
-simplifyRelocatesOffABase(IntrinsicInst *RelocatedBase,
- const SmallVectorImpl<IntrinsicInst *> &Targets) {
+simplifyRelocatesOffABase(GCRelocateInst *RelocatedBase,
+ const SmallVectorImpl<GCRelocateInst *> &Targets) {
bool MadeChange = false;
- for (auto &ToReplace : Targets) {
- GCRelocateOperands MasterRelocate(RelocatedBase);
- GCRelocateOperands ThisRelocate(ToReplace);
-
- assert(ThisRelocate.getBasePtrIndex() == MasterRelocate.getBasePtrIndex() &&
+ for (GCRelocateInst *ToReplace : Targets) {
+ assert(ToReplace->getBasePtrIndex() == RelocatedBase->getBasePtrIndex() &&
"Not relocating a derived object of the original base object");
- if (ThisRelocate.getBasePtrIndex() == ThisRelocate.getDerivedPtrIndex()) {
+ if (ToReplace->getBasePtrIndex() == ToReplace->getDerivedPtrIndex()) {
// A duplicate relocate call. TODO: coalesce duplicates.
continue;
}
- Value *Base = ThisRelocate.getBasePtr();
- auto Derived = dyn_cast<GetElementPtrInst>(ThisRelocate.getDerivedPtr());
+ if (RelocatedBase->getParent() != ToReplace->getParent()) {
+ // Base and derived relocates are in different basic blocks.
+ // In this case transform is only valid when base dominates derived
+ // relocate. However it would be too expensive to check dominance
+ // for each such relocate, so we skip the whole transformation.
+ continue;
+ }
+
+ Value *Base = ToReplace->getBasePtr();
+ auto Derived = dyn_cast<GetElementPtrInst>(ToReplace->getDerivedPtr());
if (!Derived || Derived->getPointerOperand() != Base)
continue;
// In this case, we can not find the bitcast any more. So we insert a new bitcast
// no matter there is already one or not. In this way, we can handle all cases, and
// the extra bitcast should be optimized away in later passes.
- Instruction *ActualRelocatedBase = RelocatedBase;
+ Value *ActualRelocatedBase = RelocatedBase;
if (RelocatedBase->getType() != Base->getType()) {
ActualRelocatedBase =
- cast<Instruction>(Builder.CreateBitCast(RelocatedBase, Base->getType()));
+ Builder.CreateBitCast(RelocatedBase, Base->getType());
}
Value *Replacement = Builder.CreateGEP(
Derived->getSourceElementType(), ActualRelocatedBase, makeArrayRef(OffsetV));
- Instruction *ReplacementInst = cast<Instruction>(Replacement);
Replacement->takeName(ToReplace);
// If the newly generated derived pointer's type does not match the original derived
// pointer's type, cast the new derived pointer to match it. Same reasoning as above.
- Instruction *ActualReplacement = ReplacementInst;
- if (ReplacementInst->getType() != ToReplace->getType()) {
+ Value *ActualReplacement = Replacement;
+ if (Replacement->getType() != ToReplace->getType()) {
ActualReplacement =
- cast<Instruction>(Builder.CreateBitCast(ReplacementInst, ToReplace->getType()));
+ Builder.CreateBitCast(Replacement, ToReplace->getType());
}
ToReplace->replaceAllUsesWith(ActualReplacement);
ToReplace->eraseFromParent();
// %val = load %ptr'
bool CodeGenPrepare::simplifyOffsetableRelocate(Instruction &I) {
bool MadeChange = false;
- SmallVector<User *, 2> AllRelocateCalls;
+ SmallVector<GCRelocateInst *, 2> AllRelocateCalls;
for (auto *U : I.users())
- if (isGCRelocate(dyn_cast<Instruction>(U)))
+ if (GCRelocateInst *Relocate = dyn_cast<GCRelocateInst>(U))
// Collect all the relocate calls associated with a statepoint
- AllRelocateCalls.push_back(U);
+ AllRelocateCalls.push_back(Relocate);
// We need atleast one base pointer relocation + one derived pointer
// relocation to mangle
// RelocateInstMap is a mapping from the base relocate instruction to the
// corresponding derived relocate instructions
- DenseMap<IntrinsicInst *, SmallVector<IntrinsicInst *, 2>> RelocateInstMap;
+ DenseMap<GCRelocateInst *, SmallVector<GCRelocateInst *, 2>> RelocateInstMap;
computeBaseDerivedRelocateMap(AllRelocateCalls, RelocateInstMap);
if (RelocateInstMap.empty())
return false;
// Preincrement use iterator so we don't invalidate it.
++UI;
+ // If the block selected to receive the cast is an EH pad that does not
+ // allow non-PHI instructions before the terminator, we can't sink the
+ // cast.
+ if (UserBB->getTerminator()->isEHPad())
+ continue;
+
// If this user is in the same block as the cast, don't change the cast.
if (UserBB == DefBB) continue;
if (!InsertedCast) {
BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
- InsertedCast =
- CastInst::Create(CI->getOpcode(), CI->getOperand(0), CI->getType(), "",
- InsertPt);
+ assert(InsertPt != UserBB->end());
+ InsertedCast = CastInst::Create(CI->getOpcode(), CI->getOperand(0),
+ CI->getType(), "", &*InsertPt);
}
// Replace a use of the cast with a use of the new cast.
assert(*AddI->user_begin() == CI && "expected!");
#endif
- Module *M = CI->getParent()->getParent()->getParent();
+ Module *M = CI->getModule();
Value *F = Intrinsic::getDeclaration(M, Intrinsic::uadd_with_overflow, Ty);
auto *InsertPt = AddI->hasOneUse() ? CI : AddI;
if (!InsertedCmp) {
BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
+ assert(InsertPt != UserBB->end());
InsertedCmp =
- CmpInst::Create(CI->getOpcode(),
- CI->getPredicate(), CI->getOperand(0),
- CI->getOperand(1), "", InsertPt);
+ CmpInst::Create(CI->getOpcode(), CI->getPredicate(),
+ CI->getOperand(0), CI->getOperand(1), "", &*InsertPt);
}
// Replace a use of the cmp with a use of the new cmp.
if (!InsertedShift && !InsertedTrunc) {
BasicBlock::iterator InsertPt = TruncUserBB->getFirstInsertionPt();
+ assert(InsertPt != TruncUserBB->end());
// Sink the shift
if (ShiftI->getOpcode() == Instruction::AShr)
- InsertedShift =
- BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI, "", InsertPt);
+ InsertedShift = BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI,
+ "", &*InsertPt);
else
- InsertedShift =
- BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI, "", InsertPt);
+ InsertedShift = BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI,
+ "", &*InsertPt);
// Sink the trunc
BasicBlock::iterator TruncInsertPt = TruncUserBB->getFirstInsertionPt();
TruncInsertPt++;
+ assert(TruncInsertPt != TruncUserBB->end());
InsertedTrunc = CastInst::Create(TruncI->getOpcode(), InsertedShift,
- TruncI->getType(), "", TruncInsertPt);
+ TruncI->getType(), "", &*TruncInsertPt);
MadeChange = true;
if (!InsertedShift) {
BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
+ assert(InsertPt != UserBB->end());
if (ShiftI->getOpcode() == Instruction::AShr)
- InsertedShift =
- BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI, "", InsertPt);
+ InsertedShift = BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI,
+ "", &*InsertPt);
else
- InsertedShift =
- BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI, "", InsertPt);
+ InsertedShift = BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI,
+ "", &*InsertPt);
MadeChange = true;
}
//
static void ScalarizeMaskedLoad(CallInst *CI) {
Value *Ptr = CI->getArgOperand(0);
- Value *Src0 = CI->getArgOperand(3);
+ Value *Alignment = CI->getArgOperand(1);
Value *Mask = CI->getArgOperand(2);
- VectorType *VecType = dyn_cast<VectorType>(CI->getType());
- Type *EltTy = VecType->getElementType();
+ Value *Src0 = CI->getArgOperand(3);
+ unsigned AlignVal = cast<ConstantInt>(Alignment)->getZExtValue();
+ VectorType *VecType = dyn_cast<VectorType>(CI->getType());
assert(VecType && "Unexpected return type of masked load intrinsic");
+ Type *EltTy = CI->getType()->getVectorElementType();
+
IRBuilder<> Builder(CI->getContext());
Instruction *InsertPt = CI;
BasicBlock *IfBlock = CI->getParent();
BasicBlock *CondBlock = nullptr;
BasicBlock *PrevIfBlock = CI->getParent();
- Builder.SetInsertPoint(InsertPt);
+ Builder.SetInsertPoint(InsertPt);
Builder.SetCurrentDebugLocation(CI->getDebugLoc());
+ // Short-cut if the mask is all-true.
+ bool IsAllOnesMask = isa<Constant>(Mask) &&
+ cast<Constant>(Mask)->isAllOnesValue();
+
+ if (IsAllOnesMask) {
+ Value *NewI = Builder.CreateAlignedLoad(Ptr, AlignVal);
+ CI->replaceAllUsesWith(NewI);
+ CI->eraseFromParent();
+ return;
+ }
+
+ // Adjust alignment for the scalar instruction.
+ AlignVal = std::min(AlignVal, VecType->getScalarSizeInBits()/8);
// Bitcast %addr fron i8* to EltTy*
Type *NewPtrType =
EltTy->getPointerTo(cast<PointerType>(Ptr->getType())->getAddressSpace());
Value *FirstEltPtr = Builder.CreateBitCast(Ptr, NewPtrType);
+ unsigned VectorWidth = VecType->getNumElements();
+
Value *UndefVal = UndefValue::get(VecType);
// The result vector
Value *VResult = UndefVal;
+ if (isa<ConstantVector>(Mask)) {
+ for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
+ if (cast<ConstantVector>(Mask)->getOperand(Idx)->isNullValue())
+ continue;
+ Value *Gep =
+ Builder.CreateInBoundsGEP(EltTy, FirstEltPtr, Builder.getInt32(Idx));
+ LoadInst* Load = Builder.CreateAlignedLoad(Gep, AlignVal);
+ VResult = Builder.CreateInsertElement(VResult, Load,
+ Builder.getInt32(Idx));
+ }
+ Value *NewI = Builder.CreateSelect(Mask, VResult, Src0);
+ CI->replaceAllUsesWith(NewI);
+ CI->eraseFromParent();
+ return;
+ }
+
PHINode *Phi = nullptr;
Value *PrevPhi = UndefVal;
- unsigned VectorWidth = VecType->getNumElements();
for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
// Fill the "else" block, created in the previous iteration
// %Elt = load i32* %EltAddr
// VResult = insertelement <16 x i32> VResult, i32 %Elt, i32 Idx
//
- CondBlock = IfBlock->splitBasicBlock(InsertPt, "cond.load");
+ CondBlock = IfBlock->splitBasicBlock(InsertPt->getIterator(), "cond.load");
Builder.SetInsertPoint(InsertPt);
Value *Gep =
Builder.CreateInBoundsGEP(EltTy, FirstEltPtr, Builder.getInt32(Idx));
- LoadInst* Load = Builder.CreateLoad(Gep, false);
+ LoadInst *Load = Builder.CreateAlignedLoad(Gep, AlignVal);
VResult = Builder.CreateInsertElement(VResult, Load, Builder.getInt32(Idx));
// Create "else" block, fill it in the next iteration
- BasicBlock *NewIfBlock = CondBlock->splitBasicBlock(InsertPt, "else");
+ BasicBlock *NewIfBlock =
+ CondBlock->splitBasicBlock(InsertPt->getIterator(), "else");
Builder.SetInsertPoint(InsertPt);
Instruction *OldBr = IfBlock->getTerminator();
BranchInst::Create(CondBlock, NewIfBlock, Cmp, OldBr);
// br label %else2
// . . .
static void ScalarizeMaskedStore(CallInst *CI) {
- Value *Ptr = CI->getArgOperand(1);
Value *Src = CI->getArgOperand(0);
+ Value *Ptr = CI->getArgOperand(1);
+ Value *Alignment = CI->getArgOperand(2);
Value *Mask = CI->getArgOperand(3);
+ unsigned AlignVal = cast<ConstantInt>(Alignment)->getZExtValue();
VectorType *VecType = dyn_cast<VectorType>(Src->getType());
- Type *EltTy = VecType->getElementType();
-
assert(VecType && "Unexpected data type in masked store intrinsic");
+ Type *EltTy = VecType->getElementType();
+
IRBuilder<> Builder(CI->getContext());
Instruction *InsertPt = CI;
BasicBlock *IfBlock = CI->getParent();
Builder.SetInsertPoint(InsertPt);
Builder.SetCurrentDebugLocation(CI->getDebugLoc());
+ // Short-cut if the mask is all-true.
+ bool IsAllOnesMask = isa<Constant>(Mask) &&
+ cast<Constant>(Mask)->isAllOnesValue();
+
+ if (IsAllOnesMask) {
+ Builder.CreateAlignedStore(Src, Ptr, AlignVal);
+ CI->eraseFromParent();
+ return;
+ }
+
+ // Adjust alignment for the scalar instruction.
+ AlignVal = std::max(AlignVal, VecType->getScalarSizeInBits()/8);
// Bitcast %addr fron i8* to EltTy*
Type *NewPtrType =
EltTy->getPointerTo(cast<PointerType>(Ptr->getType())->getAddressSpace());
Value *FirstEltPtr = Builder.CreateBitCast(Ptr, NewPtrType);
-
unsigned VectorWidth = VecType->getNumElements();
+
+ if (isa<ConstantVector>(Mask)) {
+ for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
+ if (cast<ConstantVector>(Mask)->getOperand(Idx)->isNullValue())
+ continue;
+ Value *OneElt = Builder.CreateExtractElement(Src, Builder.getInt32(Idx));
+ Value *Gep =
+ Builder.CreateInBoundsGEP(EltTy, FirstEltPtr, Builder.getInt32(Idx));
+ Builder.CreateAlignedStore(OneElt, Gep, AlignVal);
+ }
+ CI->eraseFromParent();
+ return;
+ }
+
for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
// Fill the "else" block, created in the previous iteration
//
// %mask_1 = extractelement <16 x i1> %mask, i32 Idx
// %to_store = icmp eq i1 %mask_1, true
- // br i1 %to_load, label %cond.store, label %else
+ // br i1 %to_store, label %cond.store, label %else
//
Value *Predicate = Builder.CreateExtractElement(Mask, Builder.getInt32(Idx));
Value *Cmp = Builder.CreateICmp(ICmpInst::ICMP_EQ, Predicate,
// %EltAddr = getelementptr i32* %1, i32 0
// %store i32 %OneElt, i32* %EltAddr
//
- BasicBlock *CondBlock = IfBlock->splitBasicBlock(InsertPt, "cond.store");
+ BasicBlock *CondBlock =
+ IfBlock->splitBasicBlock(InsertPt->getIterator(), "cond.store");
Builder.SetInsertPoint(InsertPt);
-
+
Value *OneElt = Builder.CreateExtractElement(Src, Builder.getInt32(Idx));
Value *Gep =
Builder.CreateInBoundsGEP(EltTy, FirstEltPtr, Builder.getInt32(Idx));
- Builder.CreateStore(OneElt, Gep);
+ Builder.CreateAlignedStore(OneElt, Gep, AlignVal);
+
+ // Create "else" block, fill it in the next iteration
+ BasicBlock *NewIfBlock =
+ CondBlock->splitBasicBlock(InsertPt->getIterator(), "else");
+ Builder.SetInsertPoint(InsertPt);
+ Instruction *OldBr = IfBlock->getTerminator();
+ BranchInst::Create(CondBlock, NewIfBlock, Cmp, OldBr);
+ OldBr->eraseFromParent();
+ IfBlock = NewIfBlock;
+ }
+ CI->eraseFromParent();
+}
+
+// Translate a masked gather intrinsic like
+// <16 x i32 > @llvm.masked.gather.v16i32( <16 x i32*> %Ptrs, i32 4,
+// <16 x i1> %Mask, <16 x i32> %Src)
+// to a chain of basic blocks, with loading element one-by-one if
+// the appropriate mask bit is set
+//
+// % Ptrs = getelementptr i32, i32* %base, <16 x i64> %ind
+// % Mask0 = extractelement <16 x i1> %Mask, i32 0
+// % ToLoad0 = icmp eq i1 % Mask0, true
+// br i1 % ToLoad0, label %cond.load, label %else
+//
+// cond.load:
+// % Ptr0 = extractelement <16 x i32*> %Ptrs, i32 0
+// % Load0 = load i32, i32* % Ptr0, align 4
+// % Res0 = insertelement <16 x i32> undef, i32 % Load0, i32 0
+// br label %else
+//
+// else:
+// %res.phi.else = phi <16 x i32>[% Res0, %cond.load], [undef, % 0]
+// % Mask1 = extractelement <16 x i1> %Mask, i32 1
+// % ToLoad1 = icmp eq i1 % Mask1, true
+// br i1 % ToLoad1, label %cond.load1, label %else2
+//
+// cond.load1:
+// % Ptr1 = extractelement <16 x i32*> %Ptrs, i32 1
+// % Load1 = load i32, i32* % Ptr1, align 4
+// % Res1 = insertelement <16 x i32> %res.phi.else, i32 % Load1, i32 1
+// br label %else2
+// . . .
+// % Result = select <16 x i1> %Mask, <16 x i32> %res.phi.select, <16 x i32> %Src
+// ret <16 x i32> %Result
+static void ScalarizeMaskedGather(CallInst *CI) {
+ Value *Ptrs = CI->getArgOperand(0);
+ Value *Alignment = CI->getArgOperand(1);
+ Value *Mask = CI->getArgOperand(2);
+ Value *Src0 = CI->getArgOperand(3);
+
+ VectorType *VecType = dyn_cast<VectorType>(CI->getType());
+
+ assert(VecType && "Unexpected return type of masked load intrinsic");
+
+ IRBuilder<> Builder(CI->getContext());
+ Instruction *InsertPt = CI;
+ BasicBlock *IfBlock = CI->getParent();
+ BasicBlock *CondBlock = nullptr;
+ BasicBlock *PrevIfBlock = CI->getParent();
+ Builder.SetInsertPoint(InsertPt);
+ unsigned AlignVal = cast<ConstantInt>(Alignment)->getZExtValue();
+
+ Builder.SetCurrentDebugLocation(CI->getDebugLoc());
+
+ Value *UndefVal = UndefValue::get(VecType);
+
+ // The result vector
+ Value *VResult = UndefVal;
+ unsigned VectorWidth = VecType->getNumElements();
+
+ // Shorten the way if the mask is a vector of constants.
+ bool IsConstMask = isa<ConstantVector>(Mask);
+
+ if (IsConstMask) {
+ for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
+ if (cast<ConstantVector>(Mask)->getOperand(Idx)->isNullValue())
+ continue;
+ Value *Ptr = Builder.CreateExtractElement(Ptrs, Builder.getInt32(Idx),
+ "Ptr" + Twine(Idx));
+ LoadInst *Load = Builder.CreateAlignedLoad(Ptr, AlignVal,
+ "Load" + Twine(Idx));
+ VResult = Builder.CreateInsertElement(VResult, Load,
+ Builder.getInt32(Idx),
+ "Res" + Twine(Idx));
+ }
+ Value *NewI = Builder.CreateSelect(Mask, VResult, Src0);
+ CI->replaceAllUsesWith(NewI);
+ CI->eraseFromParent();
+ return;
+ }
+
+ PHINode *Phi = nullptr;
+ Value *PrevPhi = UndefVal;
+
+ for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
+
+ // Fill the "else" block, created in the previous iteration
+ //
+ // %Mask1 = extractelement <16 x i1> %Mask, i32 1
+ // %ToLoad1 = icmp eq i1 %Mask1, true
+ // br i1 %ToLoad1, label %cond.load, label %else
+ //
+ if (Idx > 0) {
+ Phi = Builder.CreatePHI(VecType, 2, "res.phi.else");
+ Phi->addIncoming(VResult, CondBlock);
+ Phi->addIncoming(PrevPhi, PrevIfBlock);
+ PrevPhi = Phi;
+ VResult = Phi;
+ }
+
+ Value *Predicate = Builder.CreateExtractElement(Mask,
+ Builder.getInt32(Idx),
+ "Mask" + Twine(Idx));
+ Value *Cmp = Builder.CreateICmp(ICmpInst::ICMP_EQ, Predicate,
+ ConstantInt::get(Predicate->getType(), 1),
+ "ToLoad" + Twine(Idx));
+
+ // Create "cond" block
+ //
+ // %EltAddr = getelementptr i32* %1, i32 0
+ // %Elt = load i32* %EltAddr
+ // VResult = insertelement <16 x i32> VResult, i32 %Elt, i32 Idx
+ //
+ CondBlock = IfBlock->splitBasicBlock(InsertPt, "cond.load");
+ Builder.SetInsertPoint(InsertPt);
+
+ Value *Ptr = Builder.CreateExtractElement(Ptrs, Builder.getInt32(Idx),
+ "Ptr" + Twine(Idx));
+ LoadInst *Load = Builder.CreateAlignedLoad(Ptr, AlignVal,
+ "Load" + Twine(Idx));
+ VResult = Builder.CreateInsertElement(VResult, Load, Builder.getInt32(Idx),
+ "Res" + Twine(Idx));
+
+ // Create "else" block, fill it in the next iteration
+ BasicBlock *NewIfBlock = CondBlock->splitBasicBlock(InsertPt, "else");
+ Builder.SetInsertPoint(InsertPt);
+ Instruction *OldBr = IfBlock->getTerminator();
+ BranchInst::Create(CondBlock, NewIfBlock, Cmp, OldBr);
+ OldBr->eraseFromParent();
+ PrevIfBlock = IfBlock;
+ IfBlock = NewIfBlock;
+ }
+
+ Phi = Builder.CreatePHI(VecType, 2, "res.phi.select");
+ Phi->addIncoming(VResult, CondBlock);
+ Phi->addIncoming(PrevPhi, PrevIfBlock);
+ Value *NewI = Builder.CreateSelect(Mask, Phi, Src0);
+ CI->replaceAllUsesWith(NewI);
+ CI->eraseFromParent();
+}
+
+// Translate a masked scatter intrinsic, like
+// void @llvm.masked.scatter.v16i32(<16 x i32> %Src, <16 x i32*>* %Ptrs, i32 4,
+// <16 x i1> %Mask)
+// to a chain of basic blocks, that stores element one-by-one if
+// the appropriate mask bit is set.
+//
+// % Ptrs = getelementptr i32, i32* %ptr, <16 x i64> %ind
+// % Mask0 = extractelement <16 x i1> % Mask, i32 0
+// % ToStore0 = icmp eq i1 % Mask0, true
+// br i1 %ToStore0, label %cond.store, label %else
+//
+// cond.store:
+// % Elt0 = extractelement <16 x i32> %Src, i32 0
+// % Ptr0 = extractelement <16 x i32*> %Ptrs, i32 0
+// store i32 %Elt0, i32* % Ptr0, align 4
+// br label %else
+//
+// else:
+// % Mask1 = extractelement <16 x i1> % Mask, i32 1
+// % ToStore1 = icmp eq i1 % Mask1, true
+// br i1 % ToStore1, label %cond.store1, label %else2
+//
+// cond.store1:
+// % Elt1 = extractelement <16 x i32> %Src, i32 1
+// % Ptr1 = extractelement <16 x i32*> %Ptrs, i32 1
+// store i32 % Elt1, i32* % Ptr1, align 4
+// br label %else2
+// . . .
+static void ScalarizeMaskedScatter(CallInst *CI) {
+ Value *Src = CI->getArgOperand(0);
+ Value *Ptrs = CI->getArgOperand(1);
+ Value *Alignment = CI->getArgOperand(2);
+ Value *Mask = CI->getArgOperand(3);
+
+ assert(isa<VectorType>(Src->getType()) &&
+ "Unexpected data type in masked scatter intrinsic");
+ assert(isa<VectorType>(Ptrs->getType()) &&
+ isa<PointerType>(Ptrs->getType()->getVectorElementType()) &&
+ "Vector of pointers is expected in masked scatter intrinsic");
+
+ IRBuilder<> Builder(CI->getContext());
+ Instruction *InsertPt = CI;
+ BasicBlock *IfBlock = CI->getParent();
+ Builder.SetInsertPoint(InsertPt);
+ Builder.SetCurrentDebugLocation(CI->getDebugLoc());
+
+ unsigned AlignVal = cast<ConstantInt>(Alignment)->getZExtValue();
+ unsigned VectorWidth = Src->getType()->getVectorNumElements();
+
+ // Shorten the way if the mask is a vector of constants.
+ bool IsConstMask = isa<ConstantVector>(Mask);
+
+ if (IsConstMask) {
+ for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
+ if (cast<ConstantVector>(Mask)->getOperand(Idx)->isNullValue())
+ continue;
+ Value *OneElt = Builder.CreateExtractElement(Src, Builder.getInt32(Idx),
+ "Elt" + Twine(Idx));
+ Value *Ptr = Builder.CreateExtractElement(Ptrs, Builder.getInt32(Idx),
+ "Ptr" + Twine(Idx));
+ Builder.CreateAlignedStore(OneElt, Ptr, AlignVal);
+ }
+ CI->eraseFromParent();
+ return;
+ }
+ for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) {
+ // Fill the "else" block, created in the previous iteration
+ //
+ // % Mask1 = extractelement <16 x i1> % Mask, i32 Idx
+ // % ToStore = icmp eq i1 % Mask1, true
+ // br i1 % ToStore, label %cond.store, label %else
+ //
+ Value *Predicate = Builder.CreateExtractElement(Mask,
+ Builder.getInt32(Idx),
+ "Mask" + Twine(Idx));
+ Value *Cmp =
+ Builder.CreateICmp(ICmpInst::ICMP_EQ, Predicate,
+ ConstantInt::get(Predicate->getType(), 1),
+ "ToStore" + Twine(Idx));
+
+ // Create "cond" block
+ //
+ // % Elt1 = extractelement <16 x i32> %Src, i32 1
+ // % Ptr1 = extractelement <16 x i32*> %Ptrs, i32 1
+ // %store i32 % Elt1, i32* % Ptr1
+ //
+ BasicBlock *CondBlock = IfBlock->splitBasicBlock(InsertPt, "cond.store");
+ Builder.SetInsertPoint(InsertPt);
+
+ Value *OneElt = Builder.CreateExtractElement(Src, Builder.getInt32(Idx),
+ "Elt" + Twine(Idx));
+ Value *Ptr = Builder.CreateExtractElement(Ptrs, Builder.getInt32(Idx),
+ "Ptr" + Twine(Idx));
+ Builder.CreateAlignedStore(OneElt, Ptr, AlignVal);
// Create "else" block, fill it in the next iteration
BasicBlock *NewIfBlock = CondBlock->splitBasicBlock(InsertPt, "else");
CI->eraseFromParent();
}
+/// If counting leading or trailing zeros is an expensive operation and a zero
+/// input is defined, add a check for zero to avoid calling the intrinsic.
+///
+/// We want to transform:
+/// %z = call i64 @llvm.cttz.i64(i64 %A, i1 false)
+///
+/// into:
+/// entry:
+/// %cmpz = icmp eq i64 %A, 0
+/// br i1 %cmpz, label %cond.end, label %cond.false
+/// cond.false:
+/// %z = call i64 @llvm.cttz.i64(i64 %A, i1 true)
+/// br label %cond.end
+/// cond.end:
+/// %ctz = phi i64 [ 64, %entry ], [ %z, %cond.false ]
+///
+/// If the transform is performed, return true and set ModifiedDT to true.
+static bool despeculateCountZeros(IntrinsicInst *CountZeros,
+ const TargetLowering *TLI,
+ const DataLayout *DL,
+ bool &ModifiedDT) {
+ if (!TLI || !DL)
+ return false;
+
+ // If a zero input is undefined, it doesn't make sense to despeculate that.
+ if (match(CountZeros->getOperand(1), m_One()))
+ return false;
+
+ // If it's cheap to speculate, there's nothing to do.
+ auto IntrinsicID = CountZeros->getIntrinsicID();
+ if ((IntrinsicID == Intrinsic::cttz && TLI->isCheapToSpeculateCttz()) ||
+ (IntrinsicID == Intrinsic::ctlz && TLI->isCheapToSpeculateCtlz()))
+ return false;
+
+ // Only handle legal scalar cases. Anything else requires too much work.
+ Type *Ty = CountZeros->getType();
+ unsigned SizeInBits = Ty->getPrimitiveSizeInBits();
+ if (Ty->isVectorTy() || SizeInBits > DL->getLargestLegalIntTypeSize())
+ return false;
+
+ // The intrinsic will be sunk behind a compare against zero and branch.
+ BasicBlock *StartBlock = CountZeros->getParent();
+ BasicBlock *CallBlock = StartBlock->splitBasicBlock(CountZeros, "cond.false");
+
+ // Create another block after the count zero intrinsic. A PHI will be added
+ // in this block to select the result of the intrinsic or the bit-width
+ // constant if the input to the intrinsic is zero.
+ BasicBlock::iterator SplitPt = ++(BasicBlock::iterator(CountZeros));
+ BasicBlock *EndBlock = CallBlock->splitBasicBlock(SplitPt, "cond.end");
+
+ // Set up a builder to create a compare, conditional branch, and PHI.
+ IRBuilder<> Builder(CountZeros->getContext());
+ Builder.SetInsertPoint(StartBlock->getTerminator());
+ Builder.SetCurrentDebugLocation(CountZeros->getDebugLoc());
+
+ // Replace the unconditional branch that was created by the first split with
+ // a compare against zero and a conditional branch.
+ Value *Zero = Constant::getNullValue(Ty);
+ Value *Cmp = Builder.CreateICmpEQ(CountZeros->getOperand(0), Zero, "cmpz");
+ Builder.CreateCondBr(Cmp, EndBlock, CallBlock);
+ StartBlock->getTerminator()->eraseFromParent();
+
+ // Create a PHI in the end block to select either the output of the intrinsic
+ // or the bit width of the operand.
+ Builder.SetInsertPoint(&EndBlock->front());
+ PHINode *PN = Builder.CreatePHI(Ty, 2, "ctz");
+ CountZeros->replaceAllUsesWith(PN);
+ Value *BitWidth = Builder.getInt(APInt(SizeInBits, SizeInBits));
+ PN->addIncoming(BitWidth, StartBlock);
+ PN->addIncoming(CountZeros, CallBlock);
+
+ // We are explicitly handling the zero case, so we can set the intrinsic's
+ // undefined zero argument to 'true'. This will also prevent reprocessing the
+ // intrinsic; we only despeculate when a zero input is defined.
+ CountZeros->setArgOperand(1, Builder.getTrue());
+ ModifiedDT = true;
+ return true;
+}
+
bool CodeGenPrepare::optimizeCallInst(CallInst *CI, bool& ModifiedDT) {
BasicBlock *BB = CI->getParent();
// Substituting this can cause recursive simplifications, which can
// invalidate our iterator. Use a WeakVH to hold onto it in case this
// happens.
- WeakVH IterHandle(CurInstIterator);
+ WeakVH IterHandle(&*CurInstIterator);
replaceAndRecursivelySimplify(CI, RetVal,
TLInfo, nullptr);
// If the iterator instruction was recursively deleted, start over at the
// start of the block.
- if (IterHandle != CurInstIterator) {
+ if (IterHandle != CurInstIterator.getNodePtrUnchecked()) {
CurInstIterator = BB->begin();
SunkAddrs.clear();
}
}
case Intrinsic::masked_load: {
// Scalarize unsupported vector masked load
- if (!TTI->isLegalMaskedLoad(CI->getType(), 1)) {
+ if (!TTI->isLegalMaskedLoad(CI->getType())) {
ScalarizeMaskedLoad(CI);
ModifiedDT = true;
return true;
return false;
}
case Intrinsic::masked_store: {
- if (!TTI->isLegalMaskedStore(CI->getArgOperand(0)->getType(), 1)) {
+ if (!TTI->isLegalMaskedStore(CI->getArgOperand(0)->getType())) {
ScalarizeMaskedStore(CI);
ModifiedDT = true;
return true;
}
return false;
}
+ case Intrinsic::masked_gather: {
+ if (!TTI->isLegalMaskedGather(CI->getType())) {
+ ScalarizeMaskedGather(CI);
+ ModifiedDT = true;
+ return true;
+ }
+ return false;
+ }
+ case Intrinsic::masked_scatter: {
+ if (!TTI->isLegalMaskedScatter(CI->getArgOperand(0)->getType())) {
+ ScalarizeMaskedScatter(CI);
+ ModifiedDT = true;
+ return true;
+ }
+ return false;
+ }
case Intrinsic::aarch64_stlxr:
case Intrinsic::aarch64_stxr: {
ZExtInst *ExtVal = dyn_cast<ZExtInst>(CI->getArgOperand(0));
II->replaceAllUsesWith(II->getArgOperand(0));
II->eraseFromParent();
return true;
+
+ case Intrinsic::cttz:
+ case Intrinsic::ctlz:
+ // If counting zeros is expensive, try to avoid it.
+ return despeculateCountZeros(II, TLI, DL, ModifiedDT);
}
if (TLI) {
public:
/// \brief Record the position of \p Inst.
InsertionHandler(Instruction *Inst) {
- BasicBlock::iterator It = Inst;
+ BasicBlock::iterator It = Inst->getIterator();
HasPrevInstruction = (It != (Inst->getParent()->begin()));
if (HasPrevInstruction)
- Point.PrevInst = --It;
+ Point.PrevInst = &*--It;
else
Point.BB = Inst->getParent();
}
Inst->removeFromParent();
Inst->insertAfter(Point.PrevInst);
} else {
- Instruction *Position = Point.BB->getFirstInsertionPt();
+ Instruction *Position = &*Point.BB->getFirstInsertionPt();
if (Inst->getParent())
Inst->moveBefore(Position);
else
/// \brief Utility function to determine if \p OpIdx should be promoted when
/// promoting \p Inst.
static bool shouldExtOperand(const Instruction *Inst, int OpIdx) {
- if (isa<SelectInst>(Inst) && OpIdx == 0)
- return false;
- return true;
+ return !(isa<SelectInst>(Inst) && OpIdx == 0);
}
/// \brief Utility function to promote the operand of \p Ext when this
return false;
// #2 check that the truncate just drops extended bits.
- if (Inst->getType()->getIntegerBitWidth() >= OpndType->getIntegerBitWidth())
- return true;
-
- return false;
+ return Inst->getType()->getIntegerBitWidth() >=
+ OpndType->getIntegerBitWidth();
}
TypePromotionHelper::Action TypePromotionHelper::getAction(
if (Repl->use_empty()) {
// This can cause recursive deletion, which can invalidate our iterator.
// Use a WeakVH to hold onto it in case this happens.
- WeakVH IterHandle(CurInstIterator);
+ WeakVH IterHandle(&*CurInstIterator);
BasicBlock *BB = CurInstIterator->getParent();
RecursivelyDeleteTriviallyDeadInstructions(Repl, TLInfo);
- if (IterHandle != CurInstIterator) {
+ if (IterHandle != CurInstIterator.getNodePtrUnchecked()) {
// If the iterator instruction was recursively deleted, start over at the
// start of the block.
CurInstIterator = BB->begin();
if (!InsertedTrunc) {
BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
- InsertedTrunc = new TruncInst(I, Src->getType(), "", InsertPt);
+ assert(InsertPt != UserBB->end());
+ InsertedTrunc = new TruncInst(I, Src->getType(), "", &*InsertPt);
InsertedInsts.insert(InsertedTrunc);
}
return MadeChange;
}
+// Find loads whose uses only use some of the loaded value's bits. Add an "and"
+// just after the load if the target can fold this into one extload instruction,
+// with the hope of eliminating some of the other later "and" instructions using
+// the loaded value. "and"s that are made trivially redundant by the insertion
+// of the new "and" are removed by this function, while others (e.g. those whose
+// path from the load goes through a phi) are left for isel to potentially
+// remove.
+//
+// For example:
+//
+// b0:
+// x = load i32
+// ...
+// b1:
+// y = and x, 0xff
+// z = use y
+//
+// becomes:
+//
+// b0:
+// x = load i32
+// x' = and x, 0xff
+// ...
+// b1:
+// z = use x'
+//
+// whereas:
+//
+// b0:
+// x1 = load i32
+// ...
+// b1:
+// x2 = load i32
+// ...
+// b2:
+// x = phi x1, x2
+// y = and x, 0xff
+//
+// becomes (after a call to optimizeLoadExt for each load):
+//
+// b0:
+// x1 = load i32
+// x1' = and x1, 0xff
+// ...
+// b1:
+// x2 = load i32
+// x2' = and x2, 0xff
+// ...
+// b2:
+// x = phi x1', x2'
+// y = and x, 0xff
+//
+
+bool CodeGenPrepare::optimizeLoadExt(LoadInst *Load) {
+
+ if (!Load->isSimple() ||
+ !(Load->getType()->isIntegerTy() || Load->getType()->isPointerTy()))
+ return false;
+
+ // Skip loads we've already transformed or have no reason to transform.
+ if (Load->hasOneUse()) {
+ User *LoadUser = *Load->user_begin();
+ if (cast<Instruction>(LoadUser)->getParent() == Load->getParent() &&
+ !dyn_cast<PHINode>(LoadUser))
+ return false;
+ }
+
+ // Look at all uses of Load, looking through phis, to determine how many bits
+ // of the loaded value are needed.
+ SmallVector<Instruction *, 8> WorkList;
+ SmallPtrSet<Instruction *, 16> Visited;
+ SmallVector<Instruction *, 8> AndsToMaybeRemove;
+ for (auto *U : Load->users())
+ WorkList.push_back(cast<Instruction>(U));
+
+ EVT LoadResultVT = TLI->getValueType(*DL, Load->getType());
+ unsigned BitWidth = LoadResultVT.getSizeInBits();
+ APInt DemandBits(BitWidth, 0);
+ APInt WidestAndBits(BitWidth, 0);
+
+ while (!WorkList.empty()) {
+ Instruction *I = WorkList.back();
+ WorkList.pop_back();
+
+ // Break use-def graph loops.
+ if (!Visited.insert(I).second)
+ continue;
+
+ // For a PHI node, push all of its users.
+ if (auto *Phi = dyn_cast<PHINode>(I)) {
+ for (auto *U : Phi->users())
+ WorkList.push_back(cast<Instruction>(U));
+ continue;
+ }
+
+ switch (I->getOpcode()) {
+ case llvm::Instruction::And: {
+ auto *AndC = dyn_cast<ConstantInt>(I->getOperand(1));
+ if (!AndC)
+ return false;
+ APInt AndBits = AndC->getValue();
+ DemandBits |= AndBits;
+ // Keep track of the widest and mask we see.
+ if (AndBits.ugt(WidestAndBits))
+ WidestAndBits = AndBits;
+ if (AndBits == WidestAndBits && I->getOperand(0) == Load)
+ AndsToMaybeRemove.push_back(I);
+ break;
+ }
+
+ case llvm::Instruction::Shl: {
+ auto *ShlC = dyn_cast<ConstantInt>(I->getOperand(1));
+ if (!ShlC)
+ return false;
+ uint64_t ShiftAmt = ShlC->getLimitedValue(BitWidth - 1);
+ auto ShlDemandBits = APInt::getAllOnesValue(BitWidth).lshr(ShiftAmt);
+ DemandBits |= ShlDemandBits;
+ break;
+ }
+
+ case llvm::Instruction::Trunc: {
+ EVT TruncVT = TLI->getValueType(*DL, I->getType());
+ unsigned TruncBitWidth = TruncVT.getSizeInBits();
+ auto TruncBits = APInt::getAllOnesValue(TruncBitWidth).zext(BitWidth);
+ DemandBits |= TruncBits;
+ break;
+ }
+
+ default:
+ return false;
+ }
+ }
+
+ uint32_t ActiveBits = DemandBits.getActiveBits();
+ // Avoid hoisting (and (load x) 1) since it is unlikely to be folded by the
+ // target even if isLoadExtLegal says an i1 EXTLOAD is valid. For example,
+ // for the AArch64 target isLoadExtLegal(ZEXTLOAD, i32, i1) returns true, but
+ // (and (load x) 1) is not matched as a single instruction, rather as a LDR
+ // followed by an AND.
+ // TODO: Look into removing this restriction by fixing backends to either
+ // return false for isLoadExtLegal for i1 or have them select this pattern to
+ // a single instruction.
+ //
+ // Also avoid hoisting if we didn't see any ands with the exact DemandBits
+ // mask, since these are the only ands that will be removed by isel.
+ if (ActiveBits <= 1 || !APIntOps::isMask(ActiveBits, DemandBits) ||
+ WidestAndBits != DemandBits)
+ return false;
+
+ LLVMContext &Ctx = Load->getType()->getContext();
+ Type *TruncTy = Type::getIntNTy(Ctx, ActiveBits);
+ EVT TruncVT = TLI->getValueType(*DL, TruncTy);
+
+ // Reject cases that won't be matched as extloads.
+ if (!LoadResultVT.bitsGT(TruncVT) || !TruncVT.isRound() ||
+ !TLI->isLoadExtLegal(ISD::ZEXTLOAD, LoadResultVT, TruncVT))
+ return false;
+
+ IRBuilder<> Builder(Load->getNextNode());
+ auto *NewAnd = dyn_cast<Instruction>(
+ Builder.CreateAnd(Load, ConstantInt::get(Ctx, DemandBits)));
+
+ // Replace all uses of load with new and (except for the use of load in the
+ // new and itself).
+ Load->replaceAllUsesWith(NewAnd);
+ NewAnd->setOperand(0, Load);
+
+ // Remove any and instructions that are now redundant.
+ for (auto *And : AndsToMaybeRemove)
+ // Check that the and mask is the same as the one we decided to put on the
+ // new and.
+ if (cast<ConstantInt>(And->getOperand(1))->getValue() == DemandBits) {
+ And->replaceAllUsesWith(NewAnd);
+ if (&*CurInstIterator == And)
+ CurInstIterator = std::next(And->getIterator());
+ And->eraseFromParent();
+ ++NumAndUses;
+ }
+
+ ++NumAndsAdded;
+ return true;
+}
+
+/// Check if V (an operand of a select instruction) is an expensive instruction
+/// that is only used once.
+static bool sinkSelectOperand(const TargetTransformInfo *TTI, Value *V) {
+ auto *I = dyn_cast<Instruction>(V);
+ // If it's safe to speculatively execute, then it should not have side
+ // effects; therefore, it's safe to sink and possibly *not* execute.
+ return I && I->hasOneUse() && isSafeToSpeculativelyExecute(I) &&
+ TTI->getUserCost(I) >= TargetTransformInfo::TCC_Expensive;
+}
+
/// Returns true if a SelectInst should be turned into an explicit branch.
-static bool isFormingBranchFromSelectProfitable(SelectInst *SI) {
+static bool isFormingBranchFromSelectProfitable(const TargetTransformInfo *TTI,
+ SelectInst *SI) {
// FIXME: This should use the same heuristics as IfConversion to determine
// whether a select is better represented as a branch. This requires that
// branch probability metadata is preserved for the select, which is not the
// on a load from memory. But if the load is used more than once, do not
// change the select to a branch because the load is probably needed
// regardless of whether the branch is taken or not.
- return ((isa<LoadInst>(CmpOp0) && CmpOp0->hasOneUse()) ||
- (isa<LoadInst>(CmpOp1) && CmpOp1->hasOneUse()));
+ if ((isa<LoadInst>(CmpOp0) && CmpOp0->hasOneUse()) ||
+ (isa<LoadInst>(CmpOp1) && CmpOp1->hasOneUse()))
+ return true;
+
+ // If either operand of the select is expensive and only needed on one side
+ // of the select, we should form a branch.
+ if (sinkSelectOperand(TTI, SI->getTrueValue()) ||
+ sinkSelectOperand(TTI, SI->getFalseValue()))
+ return true;
+
+ return false;
}
// We have efficient codegen support for the select instruction.
// Check if it is profitable to keep this 'select'.
if (!TLI->isPredictableSelectExpensive() ||
- !isFormingBranchFromSelectProfitable(SI))
+ !isFormingBranchFromSelectProfitable(TTI, SI))
return false;
}
ModifiedDT = true;
+ // Transform a sequence like this:
+ // start:
+ // %cmp = cmp uge i32 %a, %b
+ // %sel = select i1 %cmp, i32 %c, i32 %d
+ //
+ // Into:
+ // start:
+ // %cmp = cmp uge i32 %a, %b
+ // br i1 %cmp, label %select.true, label %select.false
+ // select.true:
+ // br label %select.end
+ // select.false:
+ // br label %select.end
+ // select.end:
+ // %sel = phi i32 [ %c, %select.true ], [ %d, %select.false ]
+ //
+ // In addition, we may sink instructions that produce %c or %d from
+ // the entry block into the destination(s) of the new branch.
+ // If the true or false blocks do not contain a sunken instruction, that
+ // block and its branch may be optimized away. In that case, one side of the
+ // first branch will point directly to select.end, and the corresponding PHI
+ // predecessor block will be the start block.
+
// First, we split the block containing the select into 2 blocks.
BasicBlock *StartBlock = SI->getParent();
BasicBlock::iterator SplitPt = ++(BasicBlock::iterator(SI));
- BasicBlock *NextBlock = StartBlock->splitBasicBlock(SplitPt, "select.end");
+ BasicBlock *EndBlock = StartBlock->splitBasicBlock(SplitPt, "select.end");
- // Create a new block serving as the landing pad for the branch.
- BasicBlock *SmallBlock = BasicBlock::Create(SI->getContext(), "select.mid",
- NextBlock->getParent(), NextBlock);
-
- // Move the unconditional branch from the block with the select in it into our
- // landing pad block.
+ // Delete the unconditional branch that was just created by the split.
StartBlock->getTerminator()->eraseFromParent();
- BranchInst::Create(NextBlock, SmallBlock);
+
+ // These are the new basic blocks for the conditional branch.
+ // At least one will become an actual new basic block.
+ BasicBlock *TrueBlock = nullptr;
+ BasicBlock *FalseBlock = nullptr;
+
+ // Sink expensive instructions into the conditional blocks to avoid executing
+ // them speculatively.
+ if (sinkSelectOperand(TTI, SI->getTrueValue())) {
+ TrueBlock = BasicBlock::Create(SI->getContext(), "select.true.sink",
+ EndBlock->getParent(), EndBlock);
+ auto *TrueBranch = BranchInst::Create(EndBlock, TrueBlock);
+ auto *TrueInst = cast<Instruction>(SI->getTrueValue());
+ TrueInst->moveBefore(TrueBranch);
+ }
+ if (sinkSelectOperand(TTI, SI->getFalseValue())) {
+ FalseBlock = BasicBlock::Create(SI->getContext(), "select.false.sink",
+ EndBlock->getParent(), EndBlock);
+ auto *FalseBranch = BranchInst::Create(EndBlock, FalseBlock);
+ auto *FalseInst = cast<Instruction>(SI->getFalseValue());
+ FalseInst->moveBefore(FalseBranch);
+ }
+
+ // If there was nothing to sink, then arbitrarily choose the 'false' side
+ // for a new input value to the PHI.
+ if (TrueBlock == FalseBlock) {
+ assert(TrueBlock == nullptr &&
+ "Unexpected basic block transform while optimizing select");
+
+ FalseBlock = BasicBlock::Create(SI->getContext(), "select.false",
+ EndBlock->getParent(), EndBlock);
+ BranchInst::Create(EndBlock, FalseBlock);
+ }
// Insert the real conditional branch based on the original condition.
- BranchInst::Create(NextBlock, SmallBlock, SI->getCondition(), SI);
+ // If we did not create a new block for one of the 'true' or 'false' paths
+ // of the condition, it means that side of the branch goes to the end block
+ // directly and the path originates from the start block from the point of
+ // view of the new PHI.
+ if (TrueBlock == nullptr) {
+ BranchInst::Create(EndBlock, FalseBlock, SI->getCondition(), SI);
+ TrueBlock = StartBlock;
+ } else if (FalseBlock == nullptr) {
+ BranchInst::Create(TrueBlock, EndBlock, SI->getCondition(), SI);
+ FalseBlock = StartBlock;
+ } else {
+ BranchInst::Create(TrueBlock, FalseBlock, SI->getCondition(), SI);
+ }
// The select itself is replaced with a PHI Node.
- PHINode *PN = PHINode::Create(SI->getType(), 2, "", NextBlock->begin());
+ PHINode *PN = PHINode::Create(SI->getType(), 2, "", &EndBlock->front());
PN->takeName(SI);
- PN->addIncoming(SI->getTrueValue(), StartBlock);
- PN->addIncoming(SI->getFalseValue(), SmallBlock);
+ PN->addIncoming(SI->getTrueValue(), TrueBlock);
+ PN->addIncoming(SI->getFalseValue(), FalseBlock);
+
SI->replaceAllUsesWith(PN);
SI->eraseFromParent();
if (!InsertedShuffle) {
BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
- InsertedShuffle = new ShuffleVectorInst(SVI->getOperand(0),
- SVI->getOperand(1),
- SVI->getOperand(2), "", InsertPt);
+ assert(InsertPt != UserBB->end());
+ InsertedShuffle =
+ new ShuffleVectorInst(SVI->getOperand(0), SVI->getOperand(1),
+ SVI->getOperand(2), "", &*InsertPt);
}
UI->replaceUsesOfWith(SVI, InsertedShuffle);
return MadeChange;
}
+bool CodeGenPrepare::optimizeSwitchInst(SwitchInst *SI) {
+ if (!TLI || !DL)
+ return false;
+
+ Value *Cond = SI->getCondition();
+ Type *OldType = Cond->getType();
+ LLVMContext &Context = Cond->getContext();
+ MVT RegType = TLI->getRegisterType(Context, TLI->getValueType(*DL, OldType));
+ unsigned RegWidth = RegType.getSizeInBits();
+
+ if (RegWidth <= cast<IntegerType>(OldType)->getBitWidth())
+ return false;
+
+ // If the register width is greater than the type width, expand the condition
+ // of the switch instruction and each case constant to the width of the
+ // register. By widening the type of the switch condition, subsequent
+ // comparisons (for case comparisons) will not need to be extended to the
+ // preferred register width, so we will potentially eliminate N-1 extends,
+ // where N is the number of cases in the switch.
+ auto *NewType = Type::getIntNTy(Context, RegWidth);
+
+ // Zero-extend the switch condition and case constants unless the switch
+ // condition is a function argument that is already being sign-extended.
+ // In that case, we can avoid an unnecessary mask/extension by sign-extending
+ // everything instead.
+ Instruction::CastOps ExtType = Instruction::ZExt;
+ if (auto *Arg = dyn_cast<Argument>(Cond))
+ if (Arg->hasSExtAttr())
+ ExtType = Instruction::SExt;
+
+ auto *ExtInst = CastInst::Create(ExtType, Cond, NewType);
+ ExtInst->insertBefore(SI);
+ SI->setCondition(ExtInst);
+ for (SwitchInst::CaseIt Case : SI->cases()) {
+ APInt NarrowConst = Case.getCaseValue()->getValue();
+ APInt WideConst = (ExtType == Instruction::ZExt) ?
+ NarrowConst.zext(RegWidth) : NarrowConst.sext(RegWidth);
+ Case.setValue(ConstantInt::get(Context, WideConst));
+ }
+
+ return true;
+}
+
namespace {
/// \brief Helper class to promote a scalar operation to a vector one.
/// This class is used to move downward extractelement transition.
if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
stripInvariantGroupMetadata(*LI);
if (TLI) {
+ bool Modified = optimizeLoadExt(LI);
unsigned AS = LI->getPointerAddressSpace();
- return optimizeMemoryInst(I, I->getOperand(0), LI->getType(), AS);
+ Modified |= optimizeMemoryInst(I, I->getOperand(0), LI->getType(), AS);
+ return Modified;
}
return false;
}
if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(I))
return optimizeShuffleVectorInst(SVI);
+ if (auto *Switch = dyn_cast<SwitchInst>(I))
+ return optimizeSwitchInst(Switch);
+
if (isa<ExtractElementInst>(I))
return optimizeExtractElementInst(I);
CurInstIterator = BB.begin();
while (CurInstIterator != BB.end()) {
- MadeChange |= optimizeInst(CurInstIterator++, ModifiedDT);
+ MadeChange |= optimizeInst(&*CurInstIterator++, ModifiedDT);
if (ModifiedDT)
return true;
}
for (BasicBlock &BB : F) {
Instruction *PrevNonDbgInst = nullptr;
for (BasicBlock::iterator BI = BB.begin(), BE = BB.end(); BI != BE;) {
- Instruction *Insn = BI++;
+ Instruction *Insn = &*BI++;
DbgValueInst *DVI = dyn_cast<DbgValueInst>(Insn);
// Leave dbg.values that refer to an alloca alone. These
// instrinsics describe the address of a variable (= the alloca)
Instruction *VI = dyn_cast_or_null<Instruction>(DVI->getValue());
if (VI && VI != PrevNonDbgInst && !VI->isTerminator()) {
+ // If VI is a phi in a block with an EHPad terminator, we can't insert
+ // after it.
+ if (isa<PHINode>(VI) && VI->getParent()->getTerminator()->isEHPad())
+ continue;
DEBUG(dbgs() << "Moving Debug Value before :\n" << *DVI << ' ' << *VI);
DVI->removeFromParent();
if (isa<PHINode>(VI))
- DVI->insertBefore(VI->getParent()->getFirstInsertionPt());
+ DVI->insertBefore(&*VI->getParent()->getFirstInsertionPt());
else
DVI->insertAfter(VI);
MadeChange = true;
return false;
bool MadeChange = false;
for (Function::iterator I = F.begin(), E = F.end(); I != E; ) {
- BasicBlock *BB = I++;
+ BasicBlock *BB = &*I++;
// Does this BB end with the following?
// %andVal = and %val, #single-bit-set
projects / oota-llvm.git / blobdiff