//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "instcombine"
#include "llvm/Transforms/Scalar.h"
#include "InstCombine.h"
#include "llvm-c/Initialization.h"
using namespace llvm;
using namespace llvm::PatternMatch;
+#define DEBUG_TYPE "instcombine"
+
STATISTIC(NumCombined , "Number of insts combined");
STATISTIC(NumConstProp, "Number of constant folds");
STATISTIC(NumDeadInst , "Number of dead inst eliminated");
}
}
- return 0;
+ return nullptr;
}
// dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
if (C->getType()->getElementType()->isIntegerTy())
return ConstantExpr::getNeg(C);
- return 0;
+ return nullptr;
}
// dyn_castFNegVal - Given a 'fsub' instruction, return the RHS of the
if (C->getType()->getElementType()->isFloatingPointTy())
return ConstantExpr::getFNeg(C);
- return 0;
+ return nullptr;
}
static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO,
// not have a second operand.
Instruction *InstCombiner::FoldOpIntoSelect(Instruction &Op, SelectInst *SI) {
// Don't modify shared select instructions
- if (!SI->hasOneUse()) return 0;
+ if (!SI->hasOneUse()) return nullptr;
Value *TV = SI->getOperand(1);
Value *FV = SI->getOperand(2);
if (isa<Constant>(TV) || isa<Constant>(FV)) {
// Bool selects with constant operands can be folded to logical ops.
- if (SI->getType()->isIntegerTy(1)) return 0;
+ if (SI->getType()->isIntegerTy(1)) return nullptr;
// If it's a bitcast involving vectors, make sure it has the same number of
// elements on both sides.
VectorType *SrcTy = dyn_cast<VectorType>(BC->getSrcTy());
// Verify that either both or neither are vectors.
- if ((SrcTy == NULL) != (DestTy == NULL)) return 0;
+ if ((SrcTy == nullptr) != (DestTy == nullptr)) return nullptr;
// If vectors, verify that they have the same number of elements.
if (SrcTy && SrcTy->getNumElements() != DestTy->getNumElements())
- return 0;
+ return nullptr;
}
Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, this);
return SelectInst::Create(SI->getCondition(),
SelectTrueVal, SelectFalseVal);
}
- return 0;
+ return nullptr;
}
PHINode *PN = cast<PHINode>(I.getOperand(0));
unsigned NumPHIValues = PN->getNumIncomingValues();
if (NumPHIValues == 0)
- return 0;
+ return nullptr;
// We normally only transform phis with a single use. However, if a PHI has
// multiple uses and they are all the same operation, we can fold *all* of the
for (User *U : PN->users()) {
Instruction *UI = cast<Instruction>(U);
if (UI != &I && !I.isIdenticalTo(UI))
- return 0;
+ return nullptr;
}
// Otherwise, we can replace *all* users with the new PHI we form.
}
// remember the BB it is in. If there is more than one or if *it* is a PHI,
// bail out. We don't do arbitrary constant expressions here because moving
// their computation can be expensive without a cost model.
- BasicBlock *NonConstBB = 0;
+ BasicBlock *NonConstBB = nullptr;
for (unsigned i = 0; i != NumPHIValues; ++i) {
Value *InVal = PN->getIncomingValue(i);
if (isa<Constant>(InVal) && !isa<ConstantExpr>(InVal))
continue;
- if (isa<PHINode>(InVal)) return 0; // Itself a phi.
- if (NonConstBB) return 0; // More than one non-const value.
+ if (isa<PHINode>(InVal)) return nullptr; // Itself a phi.
+ if (NonConstBB) return nullptr; // More than one non-const value.
NonConstBB = PN->getIncomingBlock(i);
// insert a computation after it without breaking the edge.
if (InvokeInst *II = dyn_cast<InvokeInst>(InVal))
if (II->getParent() == NonConstBB)
- return 0;
+ return nullptr;
// If the incoming non-constant value is in I's block, we will remove one
// instruction, but insert another equivalent one, leading to infinite
// instcombine.
if (NonConstBB == I.getParent())
- return 0;
+ return nullptr;
}
// If there is exactly one non-constant value, we can insert a copy of the
// operation in that block. However, if this is a critical edge, we would be
// inserting the computation one some other paths (e.g. inside a loop). Only
// do this if the pred block is unconditionally branching into the phi block.
- if (NonConstBB != 0) {
+ if (NonConstBB != nullptr) {
BranchInst *BI = dyn_cast<BranchInst>(NonConstBB->getTerminator());
- if (!BI || !BI->isUnconditional()) return 0;
+ if (!BI || !BI->isUnconditional()) return nullptr;
}
// Okay, we can do the transformation: create the new PHI node.
BasicBlock *ThisBB = PN->getIncomingBlock(i);
Value *TrueVInPred = TrueV->DoPHITranslation(PhiTransBB, ThisBB);
Value *FalseVInPred = FalseV->DoPHITranslation(PhiTransBB, ThisBB);
- Value *InV = 0;
+ Value *InV = nullptr;
// Beware of ConstantExpr: it may eventually evaluate to getNullValue,
// even if currently isNullValue gives false.
Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i));
} else if (CmpInst *CI = dyn_cast<CmpInst>(&I)) {
Constant *C = cast<Constant>(I.getOperand(1));
for (unsigned i = 0; i != NumPHIValues; ++i) {
- Value *InV = 0;
+ Value *InV = nullptr;
if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i)))
InV = ConstantExpr::getCompare(CI->getPredicate(), InC, C);
else if (isa<ICmpInst>(CI))
} else if (I.getNumOperands() == 2) {
Constant *C = cast<Constant>(I.getOperand(1));
for (unsigned i = 0; i != NumPHIValues; ++i) {
- Value *InV = 0;
+ Value *InV = nullptr;
if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i)))
InV = ConstantExpr::get(I.getOpcode(), InC, C);
else
assert(PtrTy->isPtrOrPtrVectorTy());
if (!DL)
- return 0;
+ return nullptr;
Type *Ty = PtrTy->getPointerElementType();
if (!Ty->isSized())
- return 0;
+ return nullptr;
// Start with the index over the outer type. Note that the type size
// might be zero (even if the offset isn't zero) if the indexed type
while (Offset) {
// Indexing into tail padding between struct/array elements.
if (uint64_t(Offset*8) >= DL->getTypeSizeInBits(Ty))
- return 0;
+ return nullptr;
if (StructType *STy = dyn_cast<StructType>(Ty)) {
const StructLayout *SL = DL->getStructLayout(STy);
Ty = AT->getElementType();
} else {
// Otherwise, we can't index into the middle of this atomic type, bail.
- return 0;
+ return nullptr;
}
}
// If Scale is zero then it does not divide Val.
if (Scale.isMinValue())
- return 0;
+ return nullptr;
// Look through chains of multiplications, searching for a constant that is
// divisible by Scale. For example, descaling X*(Y*(Z*4)) by a factor of 4
APInt::sdivrem(CI->getValue(), Scale, Quotient, Remainder);
if (!Remainder.isMinValue())
// Not divisible by Scale.
- return 0;
+ return nullptr;
// Replace with the quotient in the parent.
Op = ConstantInt::get(CI->getType(), Quotient);
NoSignedWrap = true;
// Multiplication.
NoSignedWrap = BO->hasNoSignedWrap();
if (RequireNoSignedWrap && !NoSignedWrap)
- return 0;
+ return nullptr;
// There are three cases for multiplication: multiplication by exactly
// the scale, multiplication by a constant different to the scale, and
// Otherwise drill down into the constant.
if (!Op->hasOneUse())
- return 0;
+ return nullptr;
Parent = std::make_pair(BO, 1);
continue;
// Multiplication by something else. Drill down into the left-hand side
// since that's where the reassociate pass puts the good stuff.
if (!Op->hasOneUse())
- return 0;
+ return nullptr;
Parent = std::make_pair(BO, 0);
continue;
// Multiplication by a power of 2.
NoSignedWrap = BO->hasNoSignedWrap();
if (RequireNoSignedWrap && !NoSignedWrap)
- return 0;
+ return nullptr;
Value *LHS = BO->getOperand(0);
int32_t Amt = cast<ConstantInt>(BO->getOperand(1))->
break;
}
if (Amt < logScale || !Op->hasOneUse())
- return 0;
+ return nullptr;
// Multiplication by more than the scale. Reduce the multiplying amount
// by the scale in the parent.
}
if (!Op->hasOneUse())
- return 0;
+ return nullptr;
if (CastInst *Cast = dyn_cast<CastInst>(Op)) {
if (Cast->getOpcode() == Instruction::SExt) {
// Scale and the multiplication Y * SmallScale should not overflow.
if (SmallScale.sext(Scale.getBitWidth()) != Scale)
// SmallScale does not sign-extend to Scale.
- return 0;
+ return nullptr;
assert(SmallScale.exactLogBase2() == logScale);
// Require that Y * SmallScale must not overflow.
RequireNoSignedWrap = true;
// trunc (Y * sext Scale) does not, so nsw flags need to be cleared
// from this point up in the expression (see later).
if (RequireNoSignedWrap)
- return 0;
+ return nullptr;
// Drill down through the cast.
unsigned LargeSize = Cast->getSrcTy()->getPrimitiveSizeInBits();
}
// Unsupported expression, bail out.
- return 0;
+ return nullptr;
}
// We know that we can successfully descale, so from here on we can safely
} while (1);
}
+/// \brief Creates node of binary operation with the same attributes as the
+/// specified one but with other operands.
+static Value *CreateBinOpAsGiven(BinaryOperator &Inst, Value *LHS, Value *RHS,
+ InstCombiner::BuilderTy *B) {
+ Value *BORes = B->CreateBinOp(Inst.getOpcode(), LHS, RHS);
+ if (BinaryOperator *NewBO = dyn_cast<BinaryOperator>(BORes)) {
+ if (isa<OverflowingBinaryOperator>(NewBO)) {
+ NewBO->setHasNoSignedWrap(Inst.hasNoSignedWrap());
+ NewBO->setHasNoUnsignedWrap(Inst.hasNoUnsignedWrap());
+ }
+ if (isa<PossiblyExactOperator>(NewBO))
+ NewBO->setIsExact(Inst.isExact());
+ }
+ return BORes;
+}
+
+/// \brief Makes transformation of binary operation specific for vector types.
+/// \param Inst Binary operator to transform.
+/// \return Pointer to node that must replace the original binary operator, or
+/// null pointer if no transformation was made.
+Value *InstCombiner::SimplifyVectorOp(BinaryOperator &Inst) {
+ if (!Inst.getType()->isVectorTy()) return nullptr;
+
+ unsigned VWidth = cast<VectorType>(Inst.getType())->getNumElements();
+ Value *LHS = Inst.getOperand(0), *RHS = Inst.getOperand(1);
+ assert(cast<VectorType>(LHS->getType())->getNumElements() == VWidth);
+ assert(cast<VectorType>(RHS->getType())->getNumElements() == VWidth);
+
+ // If both arguments of binary operation are shuffles, which use the same
+ // mask and shuffle within a single vector, it is worthwhile to move the
+ // shuffle after binary operation:
+ // Op(shuffle(v1, m), shuffle(v2, m)) -> shuffle(Op(v1, v2), m)
+ if (isa<ShuffleVectorInst>(LHS) && isa<ShuffleVectorInst>(RHS)) {
+ ShuffleVectorInst *LShuf = cast<ShuffleVectorInst>(LHS);
+ ShuffleVectorInst *RShuf = cast<ShuffleVectorInst>(RHS);
+ if (isa<UndefValue>(LShuf->getOperand(1)) &&
+ isa<UndefValue>(RShuf->getOperand(1)) &&
+ LShuf->getOperand(0)->getType() == RShuf->getOperand(0)->getType() &&
+ LShuf->getMask() == RShuf->getMask()) {
+ Value *NewBO = CreateBinOpAsGiven(Inst, LShuf->getOperand(0),
+ RShuf->getOperand(0), Builder);
+ Value *Res = Builder->CreateShuffleVector(NewBO,
+ UndefValue::get(NewBO->getType()), LShuf->getMask());
+ return Res;
+ }
+ }
+
+ // If one argument is a shuffle within one vector, the other is a constant,
+ // try moving the shuffle after the binary operation.
+ ShuffleVectorInst *Shuffle = nullptr;
+ Constant *C1 = nullptr;
+ if (isa<ShuffleVectorInst>(LHS)) Shuffle = cast<ShuffleVectorInst>(LHS);
+ if (isa<ShuffleVectorInst>(RHS)) Shuffle = cast<ShuffleVectorInst>(RHS);
+ if (isa<Constant>(LHS)) C1 = cast<Constant>(LHS);
+ if (isa<Constant>(RHS)) C1 = cast<Constant>(RHS);
+ if (Shuffle && C1 && isa<UndefValue>(Shuffle->getOperand(1)) &&
+ Shuffle->getType() == Shuffle->getOperand(0)->getType()) {
+ SmallVector<int, 16> ShMask = Shuffle->getShuffleMask();
+ // Find constant C2 that has property:
+ // shuffle(C2, ShMask) = C1
+ // If such constant does not exist (example: ShMask=<0,0> and C1=<1,2>)
+ // reorder is not possible.
+ SmallVector<Constant*, 16> C2M(VWidth,
+ UndefValue::get(C1->getType()->getScalarType()));
+ bool MayChange = true;
+ for (unsigned I = 0; I < VWidth; ++I) {
+ if (ShMask[I] >= 0) {
+ assert(ShMask[I] < (int)VWidth);
+ if (!isa<UndefValue>(C2M[ShMask[I]])) {
+ MayChange = false;
+ break;
+ }
+ C2M[ShMask[I]] = C1->getAggregateElement(I);
+ }
+ }
+ if (MayChange) {
+ Constant *C2 = ConstantVector::get(C2M);
+ Value *NewLHS, *NewRHS;
+ if (isa<Constant>(LHS)) {
+ NewLHS = C2;
+ NewRHS = Shuffle->getOperand(0);
+ } else {
+ NewLHS = Shuffle->getOperand(0);
+ NewRHS = C2;
+ }
+ Value *NewBO = CreateBinOpAsGiven(Inst, NewLHS, NewRHS, Builder);
+ Value *Res = Builder->CreateShuffleVector(NewBO,
+ UndefValue::get(Inst.getType()), Shuffle->getMask());
+ return Res;
+ }
+ }
+
+ return nullptr;
+}
+
Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
SmallVector<Value*, 8> Ops(GEP.op_begin(), GEP.op_end());
//
if (GEPOperator *Src = dyn_cast<GEPOperator>(PtrOp)) {
if (!shouldMergeGEPs(*cast<GEPOperator>(&GEP), *Src))
- return 0;
+ return nullptr;
// Note that if our source is a gep chain itself then we wait for that
// chain to be resolved before we perform this transformation. This
if (GEPOperator *SrcGEP =
dyn_cast<GEPOperator>(Src->getOperand(0)))
if (SrcGEP->getNumOperands() == 2 && shouldMergeGEPs(*Src, *SrcGEP))
- return 0; // Wait until our source is folded to completion.
+ return nullptr; // Wait until our source is folded to completion.
SmallVector<Value*, 8> Indices;
// intptr_t). Just avoid transforming this until the input has been
// normalized.
if (SO1->getType() != GO1->getType())
- return 0;
+ return nullptr;
Sum = Builder->CreateAdd(SO1, GO1, PtrOp->getName()+".sum");
}
// We do not handle pointer-vector geps here.
if (!StrippedPtrTy)
- return 0;
+ return nullptr;
if (StrippedPtr != PtrOp) {
bool HasZeroPointerIndex = false;
GetElementPtrInst *Res =
GetElementPtrInst::Create(StrippedPtr, Idx, GEP.getName());
Res->setIsInBounds(GEP.isInBounds());
- return Res;
+ if (StrippedPtrTy->getAddressSpace() == GEP.getAddressSpace())
+ return Res;
+ // Insert Res, and create an addrspacecast.
+ // e.g.,
+ // GEP (addrspacecast i8 addrspace(1)* X to [0 x i8]*), i32 0, ...
+ // ->
+ // %0 = GEP i8 addrspace(1)* X, ...
+ // addrspacecast i8 addrspace(1)* %0 to i8*
+ return new AddrSpaceCastInst(Builder->Insert(Res), GEP.getType());
}
if (ArrayType *XATy =
// to an array of the same type as the destination pointer
// array. Because the array type is never stepped over (there
// is a leading zero) we can fold the cast into this GEP.
- GEP.setOperand(0, StrippedPtr);
- return &GEP;
+ if (StrippedPtrTy->getAddressSpace() == GEP.getAddressSpace()) {
+ GEP.setOperand(0, StrippedPtr);
+ return &GEP;
+ }
+ // Cannot replace the base pointer directly because StrippedPtr's
+ // address space is different. Instead, create a new GEP followed by
+ // an addrspacecast.
+ // e.g.,
+ // GEP (addrspacecast [10 x i8] addrspace(1)* X to [0 x i8]*),
+ // i32 0, ...
+ // ->
+ // %0 = GEP [10 x i8] addrspace(1)* X, ...
+ // addrspacecast i8 addrspace(1)* %0 to i8*
+ SmallVector<Value*, 8> Idx(GEP.idx_begin(), GEP.idx_end());
+ Value *NewGEP = GEP.isInBounds() ?
+ Builder->CreateInBoundsGEP(StrippedPtr, Idx, GEP.getName()) :
+ Builder->CreateGEP(StrippedPtr, Idx, GEP.getName());
+ return new AddrSpaceCastInst(NewGEP, GEP.getType());
}
}
}
}
if (!DL)
- return 0;
+ return nullptr;
/// See if we can simplify:
/// X = bitcast A* to B*
}
}
- return 0;
+ return nullptr;
}
static bool
}
return EraseInstFromFunction(MI);
}
- return 0;
+ return nullptr;
}
/// \brief Move the call to free before a NULL test.
// would duplicate the call to free in each predecessor and it may
// not be profitable even for code size.
if (!PredBB)
- return 0;
+ return nullptr;
// Validate constraint #2: Does this block contains only the call to
// free and an unconditional branch?
// FIXME: We could check if we can speculate everything in the
// predecessor block
if (FreeInstrBB->size() != 2)
- return 0;
+ return nullptr;
BasicBlock *SuccBB;
if (!match(FreeInstrBB->getTerminator(), m_UnconditionalBr(SuccBB)))
- return 0;
+ return nullptr;
// Validate the rest of constraint #1 by matching on the pred branch.
TerminatorInst *TI = PredBB->getTerminator();
BasicBlock *TrueBB, *FalseBB;
ICmpInst::Predicate Pred;
if (!match(TI, m_Br(m_ICmp(Pred, m_Specific(Op), m_Zero()), TrueBB, FalseBB)))
- return 0;
+ return nullptr;
if (Pred != ICmpInst::ICMP_EQ && Pred != ICmpInst::ICMP_NE)
- return 0;
+ return nullptr;
// Validate constraint #3: Ensure the null case just falls through.
if (SuccBB != (Pred == ICmpInst::ICMP_EQ ? TrueBB : FalseBB))
- return 0;
+ return nullptr;
assert(FreeInstrBB == (Pred == ICmpInst::ICMP_EQ ? FalseBB : TrueBB) &&
"Broken CFG: missing edge from predecessor to successor");
if (Instruction *I = tryToMoveFreeBeforeNullTest(FI))
return I;
- return 0;
+ return nullptr;
}
Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
// Change br (not X), label True, label False to: br X, label False, True
- Value *X = 0;
+ Value *X = nullptr;
BasicBlock *TrueDest;
BasicBlock *FalseDest;
if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
return &BI;
}
- return 0;
+ return nullptr;
}
Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
return &SI;
}
}
- return 0;
+ return nullptr;
}
Instruction *InstCombiner::visitExtractValueInst(ExtractValueInst &EV) {
// first index
return ExtractValueInst::Create(C2, EV.getIndices().slice(1));
}
- return 0; // Can't handle other constants
+ return nullptr; // Can't handle other constants
}
if (InsertValueInst *IV = dyn_cast<InsertValueInst>(Agg)) {
// and if again single-use then via load (gep (gep)) to load (gep).
// However, double extracts from e.g. function arguments or return values
// aren't handled yet.
- return 0;
+ return nullptr;
}
enum Personality_Type {
return &LI;
}
- return 0;
+ return nullptr;
}
for (User::op_iterator i = Inst->op_begin(), e = Inst->op_end();
i != e; ++i) {
ConstantExpr *CE = dyn_cast<ConstantExpr>(i);
- if (CE == 0) continue;
+ if (CE == nullptr) continue;
Constant*& FoldRes = FoldedConstants[CE];
if (!FoldRes)
while (!Worklist.isEmpty()) {
Instruction *I = Worklist.RemoveOne();
- if (I == 0) continue; // skip null values.
+ if (I == nullptr) continue; // skip null values.
// Check to see if we can DCE the instruction.
if (isInstructionTriviallyDead(I, TLI)) {
return false;
DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
- DL = DLP ? &DLP->getDataLayout() : 0;
+ DL = DLP ? &DLP->getDataLayout() : nullptr;
TLI = &getAnalysis<TargetLibraryInfo>();
// Minimizing size?
MinimizeSize = F.getAttributes().hasAttribute(AttributeSet::FunctionIndex,
while (DoOneIteration(F, Iteration++))
EverMadeChange = true;
- Builder = 0;
+ Builder = nullptr;
return EverMadeChange;
}
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