#include "llvm/Constants.h"
#include "llvm/Instructions.h"
#include "llvm/GlobalVariable.h"
+#include "llvm/GlobalAlias.h"
#include "llvm/IntrinsicInst.h"
+#include "llvm/LLVMContext.h"
+#include "llvm/Operator.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/MathExtras.h"
+#include "llvm/ADT/SmallPtrSet.h"
#include <cstring>
using namespace llvm;
-/// getOpcode - If this is an Instruction or a ConstantExpr, return the
-/// opcode value. Otherwise return UserOp1.
-static unsigned getOpcode(const Value *V) {
- if (const Instruction *I = dyn_cast<Instruction>(V))
- return I->getOpcode();
- if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
- return CE->getOpcode();
- // Use UserOp1 to mean there's no opcode.
- return Instruction::UserOp1;
-}
-
-
/// ComputeMaskedBits - Determine which of the bits specified in Mask are
/// known to be either zero or one and return them in the KnownZero/KnownOne
/// bit sets. This code only analyzes bits in Mask, in order to short-circuit
/// optimized based on the contradictory assumption that it is non-zero.
/// Because instcombine aggressively folds operations with undef args anyway,
/// this won't lose us code quality.
+///
+/// This function is defined on values with integer type, values with pointer
+/// type (but only if TD is non-null), and vectors of integers. In the case
+/// where V is a vector, the mask, known zero, and known one values are the
+/// same width as the vector element, and the bit is set only if it is true
+/// for all of the elements in the vector.
void llvm::ComputeMaskedBits(Value *V, const APInt &Mask,
APInt &KnownZero, APInt &KnownOne,
- TargetData *TD, unsigned Depth) {
+ const TargetData *TD, unsigned Depth) {
+ const unsigned MaxDepth = 6;
assert(V && "No Value?");
- assert(Depth <= 6 && "Limit Search Depth");
+ assert(Depth <= MaxDepth && "Limit Search Depth");
unsigned BitWidth = Mask.getBitWidth();
- assert((V->getType()->isInteger() || isa<PointerType>(V->getType())) &&
- "Not integer or pointer type!");
- assert((!TD || TD->getTypeSizeInBits(V->getType()) == BitWidth) &&
- (!isa<IntegerType>(V->getType()) ||
- V->getType()->getPrimitiveSizeInBits() == BitWidth) &&
+ assert((V->getType()->isIntOrIntVectorTy() || V->getType()->isPointerTy())
+ && "Not integer or pointer type!");
+ assert((!TD ||
+ TD->getTypeSizeInBits(V->getType()->getScalarType()) == BitWidth) &&
+ (!V->getType()->isIntOrIntVectorTy() ||
+ V->getType()->getScalarSizeInBits() == BitWidth) &&
KnownZero.getBitWidth() == BitWidth &&
KnownOne.getBitWidth() == BitWidth &&
"V, Mask, KnownOne and KnownZero should have same BitWidth");
KnownZero = ~KnownOne & Mask;
return;
}
- // Null is all-zeros.
- if (isa<ConstantPointerNull>(V)) {
+ // Null and aggregate-zero are all-zeros.
+ if (isa<ConstantPointerNull>(V) ||
+ isa<ConstantAggregateZero>(V)) {
KnownOne.clear();
KnownZero = Mask;
return;
}
+ // Handle a constant vector by taking the intersection of the known bits of
+ // each element.
+ if (ConstantVector *CV = dyn_cast<ConstantVector>(V)) {
+ KnownZero.set(); KnownOne.set();
+ for (unsigned i = 0, e = CV->getNumOperands(); i != e; ++i) {
+ APInt KnownZero2(BitWidth, 0), KnownOne2(BitWidth, 0);
+ ComputeMaskedBits(CV->getOperand(i), Mask, KnownZero2, KnownOne2,
+ TD, Depth);
+ KnownZero &= KnownZero2;
+ KnownOne &= KnownOne2;
+ }
+ return;
+ }
// The address of an aligned GlobalValue has trailing zeros.
if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
unsigned Align = GV->getAlignment();
- if (Align == 0 && TD && GV->getType()->getElementType()->isSized())
- Align = TD->getPrefTypeAlignment(GV->getType()->getElementType());
+ if (Align == 0 && TD && GV->getType()->getElementType()->isSized()) {
+ const Type *ObjectType = GV->getType()->getElementType();
+ // If the object is defined in the current Module, we'll be giving
+ // it the preferred alignment. Otherwise, we have to assume that it
+ // may only have the minimum ABI alignment.
+ if (!GV->isDeclaration() && !GV->mayBeOverridden())
+ Align = TD->getPrefTypeAlignment(ObjectType);
+ else
+ Align = TD->getABITypeAlignment(ObjectType);
+ }
if (Align > 0)
KnownZero = Mask & APInt::getLowBitsSet(BitWidth,
CountTrailingZeros_32(Align));
KnownOne.clear();
return;
}
+ // A weak GlobalAlias is totally unknown. A non-weak GlobalAlias has
+ // the bits of its aliasee.
+ if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
+ if (GA->mayBeOverridden()) {
+ KnownZero.clear(); KnownOne.clear();
+ } else {
+ ComputeMaskedBits(GA->getAliasee(), Mask, KnownZero, KnownOne,
+ TD, Depth+1);
+ }
+ return;
+ }
KnownZero.clear(); KnownOne.clear(); // Start out not knowing anything.
- if (Depth == 6 || Mask == 0)
+ if (Depth == MaxDepth || Mask == 0)
return; // Limit search depth.
- User *I = dyn_cast<User>(V);
+ Operator *I = dyn_cast<Operator>(V);
if (!I) return;
APInt KnownZero2(KnownZero), KnownOne2(KnownOne);
- switch (getOpcode(I)) {
+ switch (I->getOpcode()) {
default: break;
case Instruction::And: {
// If either the LHS or the RHS are Zero, the result is zero.
// FALL THROUGH and handle them the same as zext/trunc.
case Instruction::ZExt:
case Instruction::Trunc: {
+ const Type *SrcTy = I->getOperand(0)->getType();
+
+ unsigned SrcBitWidth;
// Note that we handle pointer operands here because of inttoptr/ptrtoint
// which fall through here.
- const Type *SrcTy = I->getOperand(0)->getType();
- unsigned SrcBitWidth = TD ?
- TD->getTypeSizeInBits(SrcTy) :
- SrcTy->getPrimitiveSizeInBits();
+ if (SrcTy->isPointerTy())
+ SrcBitWidth = TD->getTypeSizeInBits(SrcTy);
+ else
+ SrcBitWidth = SrcTy->getScalarSizeInBits();
+
APInt MaskIn(Mask);
MaskIn.zextOrTrunc(SrcBitWidth);
KnownZero.zextOrTrunc(SrcBitWidth);
}
case Instruction::BitCast: {
const Type *SrcTy = I->getOperand(0)->getType();
- if (SrcTy->isInteger() || isa<PointerType>(SrcTy)) {
+ if ((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
+ // TODO: For now, not handling conversions like:
+ // (bitcast i64 %x to <2 x i32>)
+ !I->getType()->isVectorTy()) {
ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, TD,
Depth+1);
return;
}
case Instruction::SExt: {
// Compute the bits in the result that are not present in the input.
- const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType());
- unsigned SrcBitWidth = SrcTy->getBitWidth();
+ unsigned SrcBitWidth = I->getOperand(0)->getType()->getScalarSizeInBits();
APInt MaskIn(Mask);
MaskIn.trunc(SrcBitWidth);
APInt Mask2(Mask.shl(ShiftAmt));
ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero,KnownOne, TD,
Depth+1);
- assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?");
+ assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
KnownZero = APIntOps::lshr(KnownZero, ShiftAmt);
KnownOne = APIntOps::lshr(KnownOne, ShiftAmt);
// high bits known zero.
APInt Mask2(Mask.shl(ShiftAmt));
ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero, KnownOne, TD,
Depth+1);
- assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?");
+ assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
KnownZero = APIntOps::lshr(KnownZero, ShiftAmt);
KnownOne = APIntOps::lshr(KnownOne, ShiftAmt);
}
// fall through
case Instruction::Add: {
- // Output known-0 bits are known if clear or set in both the low clear bits
- // common to both LHS & RHS. For example, 8+(X<<3) is known to have the
- // low 3 bits clear.
- APInt Mask2 = APInt::getLowBitsSet(BitWidth, Mask.countTrailingOnes());
- ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero2, KnownOne2, TD,
+ // If one of the operands has trailing zeros, then the bits that the
+ // other operand has in those bit positions will be preserved in the
+ // result. For an add, this works with either operand. For a subtract,
+ // this only works if the known zeros are in the right operand.
+ APInt LHSKnownZero(BitWidth, 0), LHSKnownOne(BitWidth, 0);
+ APInt Mask2 = APInt::getLowBitsSet(BitWidth,
+ BitWidth - Mask.countLeadingZeros());
+ ComputeMaskedBits(I->getOperand(0), Mask2, LHSKnownZero, LHSKnownOne, TD,
Depth+1);
- assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
- unsigned KnownZeroOut = KnownZero2.countTrailingOnes();
+ assert((LHSKnownZero & LHSKnownOne) == 0 &&
+ "Bits known to be one AND zero?");
+ unsigned LHSKnownZeroOut = LHSKnownZero.countTrailingOnes();
ComputeMaskedBits(I->getOperand(1), Mask2, KnownZero2, KnownOne2, TD,
Depth+1);
assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
- KnownZeroOut = std::min(KnownZeroOut,
- KnownZero2.countTrailingOnes());
+ unsigned RHSKnownZeroOut = KnownZero2.countTrailingOnes();
- KnownZero |= APInt::getLowBitsSet(BitWidth, KnownZeroOut);
+ // Determine which operand has more trailing zeros, and use that
+ // many bits from the other operand.
+ if (LHSKnownZeroOut > RHSKnownZeroOut) {
+ if (I->getOpcode() == Instruction::Add) {
+ APInt Mask = APInt::getLowBitsSet(BitWidth, LHSKnownZeroOut);
+ KnownZero |= KnownZero2 & Mask;
+ KnownOne |= KnownOne2 & Mask;
+ } else {
+ // If the known zeros are in the left operand for a subtract,
+ // fall back to the minimum known zeros in both operands.
+ KnownZero |= APInt::getLowBitsSet(BitWidth,
+ std::min(LHSKnownZeroOut,
+ RHSKnownZeroOut));
+ }
+ } else if (RHSKnownZeroOut >= LHSKnownZeroOut) {
+ APInt Mask = APInt::getLowBitsSet(BitWidth, RHSKnownZeroOut);
+ KnownZero |= LHSKnownZero & Mask;
+ KnownOne |= LHSKnownOne & Mask;
+ }
return;
}
case Instruction::SRem:
if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) {
- APInt RA = Rem->getValue();
- if (RA.isPowerOf2() || (-RA).isPowerOf2()) {
- APInt LowBits = RA.isStrictlyPositive() ? (RA - 1) : ~RA;
+ APInt RA = Rem->getValue().abs();
+ if (RA.isPowerOf2()) {
+ APInt LowBits = RA - 1;
APInt Mask2 = LowBits | APInt::getSignBit(BitWidth);
ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero2, KnownOne2, TD,
Depth+1);
- // If the sign bit of the first operand is zero, the sign bit of
- // the result is zero. If the first operand has no one bits below
- // the second operand's single 1 bit, its sign will be zero.
+ // The low bits of the first operand are unchanged by the srem.
+ KnownZero = KnownZero2 & LowBits;
+ KnownOne = KnownOne2 & LowBits;
+
+ // If the first operand is non-negative or has all low bits zero, then
+ // the upper bits are all zero.
if (KnownZero2[BitWidth-1] || ((KnownZero2 & LowBits) == LowBits))
- KnownZero2 |= ~LowBits;
+ KnownZero |= ~LowBits;
- KnownZero |= KnownZero2 & Mask;
+ // If the first operand is negative and not all low bits are zero, then
+ // the upper bits are all one.
+ if (KnownOne2[BitWidth-1] && ((KnownOne2 & LowBits) != 0))
+ KnownOne |= ~LowBits;
- assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?");
+ KnownZero &= Mask;
+ KnownOne &= Mask;
+
+ assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
}
}
break;
KnownZero |= ~LowBits & Mask;
ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero, KnownOne, TD,
Depth+1);
- assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?");
+ assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
break;
}
}
break;
}
- case Instruction::Alloca:
- case Instruction::Malloc: {
- AllocationInst *AI = cast<AllocationInst>(V);
+ case Instruction::Alloca: {
+ AllocaInst *AI = cast<AllocaInst>(V);
unsigned Align = AI->getAlignment();
- if (Align == 0 && TD) {
- if (isa<AllocaInst>(AI))
- Align = TD->getABITypeAlignment(AI->getType()->getElementType());
- else if (isa<MallocInst>(AI)) {
- // Malloc returns maximally aligned memory.
- Align = TD->getABITypeAlignment(AI->getType()->getElementType());
- Align =
- std::max(Align,
- (unsigned)TD->getABITypeAlignment(Type::DoubleTy));
- Align =
- std::max(Align,
- (unsigned)TD->getABITypeAlignment(Type::Int64Ty));
- }
- }
+ if (Align == 0 && TD)
+ Align = TD->getABITypeAlignment(AI->getType()->getElementType());
if (Align > 0)
KnownZero = Mask & APInt::getLowBitsSet(BitWidth,
// Handle array index arithmetic.
const Type *IndexedTy = GTI.getIndexedType();
if (!IndexedTy->isSized()) return;
- unsigned GEPOpiBits = Index->getType()->getPrimitiveSizeInBits();
- uint64_t TypeSize = TD ? TD->getTypePaddedSize(IndexedTy) : 1;
+ unsigned GEPOpiBits = Index->getType()->getScalarSizeInBits();
+ uint64_t TypeSize = TD ? TD->getTypeAllocSize(IndexedTy) : 1;
LocalMask = APInt::getAllOnesValue(GEPOpiBits);
LocalKnownZero = LocalKnownOne = APInt(GEPOpiBits, 0);
ComputeMaskedBits(Index, LocalMask,
for (unsigned i = 0; i != 2; ++i) {
Value *L = P->getIncomingValue(i);
Value *R = P->getIncomingValue(!i);
- User *LU = dyn_cast<User>(L);
+ Operator *LU = dyn_cast<Operator>(L);
if (!LU)
continue;
- unsigned Opcode = getOpcode(LU);
+ unsigned Opcode = LU->getOpcode();
// Check for operations that have the property that if
// both their operands have low zero bits, the result
// will have low zero bits.
}
}
}
+
+ // Otherwise take the unions of the known bit sets of the operands,
+ // taking conservative care to avoid excessive recursion.
+ if (Depth < MaxDepth - 1 && !KnownZero && !KnownOne) {
+ KnownZero = APInt::getAllOnesValue(BitWidth);
+ KnownOne = APInt::getAllOnesValue(BitWidth);
+ for (unsigned i = 0, e = P->getNumIncomingValues(); i != e; ++i) {
+ // Skip direct self references.
+ if (P->getIncomingValue(i) == P) continue;
+
+ KnownZero2 = APInt(BitWidth, 0);
+ KnownOne2 = APInt(BitWidth, 0);
+ // Recurse, but cap the recursion to one level, because we don't
+ // want to waste time spinning around in loops.
+ ComputeMaskedBits(P->getIncomingValue(i), KnownZero | KnownOne,
+ KnownZero2, KnownOne2, TD, MaxDepth-1);
+ KnownZero &= KnownZero2;
+ KnownOne &= KnownOne2;
+ // If all bits have been ruled out, there's no need to check
+ // more operands.
+ if (!KnownZero && !KnownOne)
+ break;
+ }
+ }
break;
}
case Instruction::Call:
/// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use
/// this predicate to simplify operations downstream. Mask is known to be zero
/// for bits that V cannot have.
+///
+/// This function is defined on values with integer type, values with pointer
+/// type (but only if TD is non-null), and vectors of integers. In the case
+/// where V is a vector, the mask, known zero, and known one values are the
+/// same width as the vector element, and the bit is set only if it is true
+/// for all of the elements in the vector.
bool llvm::MaskedValueIsZero(Value *V, const APInt &Mask,
- TargetData *TD, unsigned Depth) {
+ const TargetData *TD, unsigned Depth) {
APInt KnownZero(Mask.getBitWidth(), 0), KnownOne(Mask.getBitWidth(), 0);
ComputeMaskedBits(V, Mask, KnownZero, KnownOne, TD, Depth);
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
///
/// 'Op' must have a scalar integer type.
///
-unsigned llvm::ComputeNumSignBits(Value *V, TargetData *TD, unsigned Depth) {
- const IntegerType *Ty = cast<IntegerType>(V->getType());
- unsigned TyBits = Ty->getBitWidth();
+unsigned llvm::ComputeNumSignBits(Value *V, const TargetData *TD,
+ unsigned Depth) {
+ assert((TD || V->getType()->isIntOrIntVectorTy()) &&
+ "ComputeNumSignBits requires a TargetData object to operate "
+ "on non-integer values!");
+ const Type *Ty = V->getType();
+ unsigned TyBits = TD ? TD->getTypeSizeInBits(V->getType()->getScalarType()) :
+ Ty->getScalarSizeInBits();
unsigned Tmp, Tmp2;
unsigned FirstAnswer = 1;
if (Depth == 6)
return 1; // Limit search depth.
- User *U = dyn_cast<User>(V);
- switch (getOpcode(V)) {
+ Operator *U = dyn_cast<Operator>(V);
+ switch (Operator::getOpcode(V)) {
default: break;
case Instruction::SExt:
- Tmp = TyBits-cast<IntegerType>(U->getOperand(0)->getType())->getBitWidth();
+ Tmp = TyBits - U->getOperand(0)->getType()->getScalarSizeInBits();
return ComputeNumSignBits(U->getOperand(0), TD, Depth+1) + Tmp;
case Instruction::AShr:
if (Tmp == 1) return 1; // Early out.
// Special case decrementing a value (ADD X, -1):
- if (ConstantInt *CRHS = dyn_cast<ConstantInt>(U->getOperand(0)))
+ if (ConstantInt *CRHS = dyn_cast<ConstantInt>(U->getOperand(1)))
if (CRHS->isAllOnesValue()) {
APInt KnownZero(TyBits, 0), KnownOne(TyBits, 0);
APInt Mask = APInt::getAllOnesValue(TyBits);
Tmp2 = ComputeNumSignBits(U->getOperand(1), TD, Depth+1);
if (Tmp2 == 1) return 1;
- return std::min(Tmp, Tmp2)-1;
- break;
+ return std::min(Tmp, Tmp2)-1;
case Instruction::Sub:
Tmp2 = ComputeNumSignBits(U->getOperand(1), TD, Depth+1);
// is, at worst, one more bit than the inputs.
Tmp = ComputeNumSignBits(U->getOperand(0), TD, Depth+1);
if (Tmp == 1) return 1; // Early out.
- return std::min(Tmp, Tmp2)-1;
- break;
+ return std::min(Tmp, Tmp2)-1;
+
+ case Instruction::PHI: {
+ PHINode *PN = cast<PHINode>(U);
+ // Don't analyze large in-degree PHIs.
+ if (PN->getNumIncomingValues() > 4) break;
+
+ // Take the minimum of all incoming values. This can't infinitely loop
+ // because of our depth threshold.
+ Tmp = ComputeNumSignBits(PN->getIncomingValue(0), TD, Depth+1);
+ for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i) {
+ if (Tmp == 1) return Tmp;
+ Tmp = std::min(Tmp,
+ ComputeNumSignBits(PN->getIncomingValue(i), TD, Depth+1));
+ }
+ return Tmp;
+ }
+
case Instruction::Trunc:
// FIXME: it's tricky to do anything useful for this, but it is an important
// case for targets like X86.
return std::max(FirstAnswer, std::min(TyBits, Mask.countLeadingZeros()));
}
+/// ComputeMultiple - This function computes the integer multiple of Base that
+/// equals V. If successful, it returns true and returns the multiple in
+/// Multiple. If unsuccessful, it returns false. It looks
+/// through SExt instructions only if LookThroughSExt is true.
+bool llvm::ComputeMultiple(Value *V, unsigned Base, Value *&Multiple,
+ bool LookThroughSExt, unsigned Depth) {
+ const unsigned MaxDepth = 6;
+
+ assert(V && "No Value?");
+ assert(Depth <= MaxDepth && "Limit Search Depth");
+ assert(V->getType()->isIntegerTy() && "Not integer or pointer type!");
+
+ const Type *T = V->getType();
+
+ ConstantInt *CI = dyn_cast<ConstantInt>(V);
+
+ if (Base == 0)
+ return false;
+
+ if (Base == 1) {
+ Multiple = V;
+ return true;
+ }
+
+ ConstantExpr *CO = dyn_cast<ConstantExpr>(V);
+ Constant *BaseVal = ConstantInt::get(T, Base);
+ if (CO && CO == BaseVal) {
+ // Multiple is 1.
+ Multiple = ConstantInt::get(T, 1);
+ return true;
+ }
+
+ if (CI && CI->getZExtValue() % Base == 0) {
+ Multiple = ConstantInt::get(T, CI->getZExtValue() / Base);
+ return true;
+ }
+
+ if (Depth == MaxDepth) return false; // Limit search depth.
+
+ Operator *I = dyn_cast<Operator>(V);
+ if (!I) return false;
+
+ switch (I->getOpcode()) {
+ default: break;
+ case Instruction::SExt:
+ if (!LookThroughSExt) return false;
+ // otherwise fall through to ZExt
+ case Instruction::ZExt:
+ return ComputeMultiple(I->getOperand(0), Base, Multiple,
+ LookThroughSExt, Depth+1);
+ case Instruction::Shl:
+ case Instruction::Mul: {
+ Value *Op0 = I->getOperand(0);
+ Value *Op1 = I->getOperand(1);
+
+ if (I->getOpcode() == Instruction::Shl) {
+ ConstantInt *Op1CI = dyn_cast<ConstantInt>(Op1);
+ if (!Op1CI) return false;
+ // Turn Op0 << Op1 into Op0 * 2^Op1
+ APInt Op1Int = Op1CI->getValue();
+ uint64_t BitToSet = Op1Int.getLimitedValue(Op1Int.getBitWidth() - 1);
+ Op1 = ConstantInt::get(V->getContext(),
+ APInt(Op1Int.getBitWidth(), 0).set(BitToSet));
+ }
+
+ Value *Mul0 = NULL;
+ Value *Mul1 = NULL;
+ bool M0 = ComputeMultiple(Op0, Base, Mul0,
+ LookThroughSExt, Depth+1);
+ bool M1 = ComputeMultiple(Op1, Base, Mul1,
+ LookThroughSExt, Depth+1);
+
+ if (M0) {
+ if (isa<Constant>(Op1) && isa<Constant>(Mul0)) {
+ // V == Base * (Mul0 * Op1), so return (Mul0 * Op1)
+ Multiple = ConstantExpr::getMul(cast<Constant>(Mul0),
+ cast<Constant>(Op1));
+ return true;
+ }
+
+ if (ConstantInt *Mul0CI = dyn_cast<ConstantInt>(Mul0))
+ if (Mul0CI->getValue() == 1) {
+ // V == Base * Op1, so return Op1
+ Multiple = Op1;
+ return true;
+ }
+ }
+
+ if (M1) {
+ if (isa<Constant>(Op0) && isa<Constant>(Mul1)) {
+ // V == Base * (Mul1 * Op0), so return (Mul1 * Op0)
+ Multiple = ConstantExpr::getMul(cast<Constant>(Mul1),
+ cast<Constant>(Op0));
+ return true;
+ }
+
+ if (ConstantInt *Mul1CI = dyn_cast<ConstantInt>(Mul1))
+ if (Mul1CI->getValue() == 1) {
+ // V == Base * Op0, so return Op0
+ Multiple = Op0;
+ return true;
+ }
+ }
+ }
+ }
+
+ // We could not determine if V is a multiple of Base.
+ return false;
+}
+
/// CannotBeNegativeZero - Return true if we can prove that the specified FP
/// value is never equal to -0.0.
///
if (Depth == 6)
return 1; // Limit search depth.
- const Instruction *I = dyn_cast<Instruction>(V);
+ const Operator *I = dyn_cast<Operator>(V);
if (I == 0) return false;
// (add x, 0.0) is guaranteed to return +0.0, not -0.0.
- if (I->getOpcode() == Instruction::Add &&
+ if (I->getOpcode() == Instruction::FAdd &&
isa<ConstantFP>(I->getOperand(1)) &&
cast<ConstantFP>(I->getOperand(1))->isNullValue())
return true;
if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(I))
// sqrt(-0.0) = -0.0, no other negative results are possible.
if (II->getIntrinsicID() == Intrinsic::sqrt)
- return CannotBeNegativeZero(II->getOperand(1), Depth+1);
+ return CannotBeNegativeZero(II->getArgOperand(0), Depth+1);
if (const CallInst *CI = dyn_cast<CallInst>(I))
if (const Function *F = CI->getCalledFunction()) {
if (F->isDeclaration()) {
- switch (F->getNameLen()) {
- case 3: // abs(x) != -0.0
- if (!strcmp(F->getNameStart(), "abs")) return true;
+ // abs(x) != -0.0
+ if (F->getName() == "abs") return true;
+ // fabs[lf](x) != -0.0
+ if (F->getName() == "fabs") return true;
+ if (F->getName() == "fabsf") return true;
+ if (F->getName() == "fabsl") return true;
+ if (F->getName() == "sqrt" || F->getName() == "sqrtf" ||
+ F->getName() == "sqrtl")
+ return CannotBeNegativeZero(CI->getArgOperand(0), Depth+1);
+ }
+ }
+
+ return false;
+}
+
+
+/// GetLinearExpression - Analyze the specified value as a linear expression:
+/// "A*V + B", where A and B are constant integers. Return the scale and offset
+/// values as APInts and return V as a Value*. The incoming Value is known to
+/// have IntegerType. Note that this looks through extends, so the high bits
+/// may not be represented in the result.
+static Value *GetLinearExpression(Value *V, APInt &Scale, APInt &Offset,
+ const TargetData *TD, unsigned Depth) {
+ assert(V->getType()->isIntegerTy() && "Not an integer value");
+
+ // Limit our recursion depth.
+ if (Depth == 6) {
+ Scale = 1;
+ Offset = 0;
+ return V;
+ }
+
+ if (BinaryOperator *BOp = dyn_cast<BinaryOperator>(V)) {
+ if (ConstantInt *RHSC = dyn_cast<ConstantInt>(BOp->getOperand(1))) {
+ switch (BOp->getOpcode()) {
+ default: break;
+ case Instruction::Or:
+ // X|C == X+C if all the bits in C are unset in X. Otherwise we can't
+ // analyze it.
+ if (!MaskedValueIsZero(BOp->getOperand(0), RHSC->getValue(), TD))
break;
- case 4: // abs[lf](x) != -0.0
- if (!strcmp(F->getNameStart(), "absf")) return true;
- if (!strcmp(F->getNameStart(), "absl")) return true;
+ // FALL THROUGH.
+ case Instruction::Add:
+ V = GetLinearExpression(BOp->getOperand(0), Scale, Offset, TD, Depth+1);
+ Offset += RHSC->getValue();
+ return V;
+ case Instruction::Mul:
+ V = GetLinearExpression(BOp->getOperand(0), Scale, Offset, TD, Depth+1);
+ Offset *= RHSC->getValue();
+ Scale *= RHSC->getValue();
+ return V;
+ case Instruction::Shl:
+ V = GetLinearExpression(BOp->getOperand(0), Scale, Offset, TD, Depth+1);
+ Offset <<= RHSC->getValue().getLimitedValue();
+ Scale <<= RHSC->getValue().getLimitedValue();
+ return V;
+ }
+ }
+ }
+
+ // Since clients don't care about the high bits of the value, just scales and
+ // offsets, we can look through extensions.
+ if (isa<SExtInst>(V) || isa<ZExtInst>(V)) {
+ Value *CastOp = cast<CastInst>(V)->getOperand(0);
+ unsigned OldWidth = Scale.getBitWidth();
+ unsigned SmallWidth = CastOp->getType()->getPrimitiveSizeInBits();
+ Scale.trunc(SmallWidth);
+ Offset.trunc(SmallWidth);
+ Value *Result = GetLinearExpression(CastOp, Scale, Offset, TD, Depth+1);
+ Scale.zext(OldWidth);
+ Offset.zext(OldWidth);
+ return Result;
+ }
+
+ Scale = 1;
+ Offset = 0;
+ return V;
+}
+
+/// DecomposeGEPExpression - If V is a symbolic pointer expression, decompose it
+/// into a base pointer with a constant offset and a number of scaled symbolic
+/// offsets.
+///
+/// The scaled symbolic offsets (represented by pairs of a Value* and a scale in
+/// the VarIndices vector) are Value*'s that are known to be scaled by the
+/// specified amount, but which may have other unrepresented high bits. As such,
+/// the gep cannot necessarily be reconstructed from its decomposed form.
+///
+/// When TargetData is around, this function is capable of analyzing everything
+/// that Value::getUnderlyingObject() can look through. When not, it just looks
+/// through pointer casts.
+///
+const Value *llvm::DecomposeGEPExpression(const Value *V, int64_t &BaseOffs,
+ SmallVectorImpl<std::pair<const Value*, int64_t> > &VarIndices,
+ const TargetData *TD) {
+ // Limit recursion depth to limit compile time in crazy cases.
+ unsigned MaxLookup = 6;
+
+ BaseOffs = 0;
+ do {
+ // See if this is a bitcast or GEP.
+ const Operator *Op = dyn_cast<Operator>(V);
+ if (Op == 0) {
+ // The only non-operator case we can handle are GlobalAliases.
+ if (const GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
+ if (!GA->mayBeOverridden()) {
+ V = GA->getAliasee();
+ continue;
+ }
+ }
+ return V;
+ }
+
+ if (Op->getOpcode() == Instruction::BitCast) {
+ V = Op->getOperand(0);
+ continue;
+ }
+
+ const GEPOperator *GEPOp = dyn_cast<GEPOperator>(Op);
+ if (GEPOp == 0)
+ return V;
+
+ // Don't attempt to analyze GEPs over unsized objects.
+ if (!cast<PointerType>(GEPOp->getOperand(0)->getType())
+ ->getElementType()->isSized())
+ return V;
+
+ // If we are lacking TargetData information, we can't compute the offets of
+ // elements computed by GEPs. However, we can handle bitcast equivalent
+ // GEPs.
+ if (!TD) {
+ if (!GEPOp->hasAllZeroIndices())
+ return V;
+ V = GEPOp->getOperand(0);
+ continue;
+ }
+
+ // Walk the indices of the GEP, accumulating them into BaseOff/VarIndices.
+ gep_type_iterator GTI = gep_type_begin(GEPOp);
+ for (User::const_op_iterator I = GEPOp->op_begin()+1,
+ E = GEPOp->op_end(); I != E; ++I) {
+ Value *Index = *I;
+ // Compute the (potentially symbolic) offset in bytes for this index.
+ if (const StructType *STy = dyn_cast<StructType>(*GTI++)) {
+ // For a struct, add the member offset.
+ unsigned FieldNo = cast<ConstantInt>(Index)->getZExtValue();
+ if (FieldNo == 0) continue;
+
+ BaseOffs += TD->getStructLayout(STy)->getElementOffset(FieldNo);
+ continue;
+ }
+
+ // For an array/pointer, add the element offset, explicitly scaled.
+ if (ConstantInt *CIdx = dyn_cast<ConstantInt>(Index)) {
+ if (CIdx->isZero()) continue;
+ BaseOffs += TD->getTypeAllocSize(*GTI)*CIdx->getSExtValue();
+ continue;
+ }
+
+ uint64_t Scale = TD->getTypeAllocSize(*GTI);
+
+ // Use GetLinearExpression to decompose the index into a C1*V+C2 form.
+ unsigned Width = cast<IntegerType>(Index->getType())->getBitWidth();
+ APInt IndexScale(Width, 0), IndexOffset(Width, 0);
+ Index = GetLinearExpression(Index, IndexScale, IndexOffset, TD, 0);
+
+ // The GEP index scale ("Scale") scales C1*V+C2, yielding (C1*V+C2)*Scale.
+ // This gives us an aggregate computation of (C1*Scale)*V + C2*Scale.
+ BaseOffs += IndexOffset.getZExtValue()*Scale;
+ Scale *= IndexScale.getZExtValue();
+
+
+ // If we already had an occurrance of this index variable, merge this
+ // scale into it. For example, we want to handle:
+ // A[x][x] -> x*16 + x*4 -> x*20
+ // This also ensures that 'x' only appears in the index list once.
+ for (unsigned i = 0, e = VarIndices.size(); i != e; ++i) {
+ if (VarIndices[i].first == Index) {
+ Scale += VarIndices[i].second;
+ VarIndices.erase(VarIndices.begin()+i);
break;
}
}
+
+ // Make sure that we have a scale that makes sense for this target's
+ // pointer size.
+ if (unsigned ShiftBits = 64-TD->getPointerSizeInBits()) {
+ Scale <<= ShiftBits;
+ Scale >>= ShiftBits;
+ }
+
+ if (Scale)
+ VarIndices.push_back(std::make_pair(Index, Scale));
}
+
+ // Analyze the base pointer next.
+ V = GEPOp->getOperand(0);
+ } while (--MaxLookup);
- return false;
+ // If the chain of expressions is too deep, just return early.
+ return V;
}
+
// This is the recursive version of BuildSubAggregate. It takes a few different
// arguments. Idxs is the index within the nested struct From that we are
// looking at now (which is of type IndexedType). IdxSkip is the number of
// indices from Idxs that should be left out when inserting into the resulting
// struct. To is the result struct built so far, new insertvalue instructions
// build on that.
-Value *BuildSubAggregate(Value *From, Value* To, const Type *IndexedType,
- SmallVector<unsigned, 10> &Idxs,
- unsigned IdxSkip,
- Instruction *InsertBefore) {
+static Value *BuildSubAggregate(Value *From, Value* To, const Type *IndexedType,
+ SmallVector<unsigned, 10> &Idxs,
+ unsigned IdxSkip,
+ Instruction *InsertBefore) {
const llvm::StructType *STy = llvm::dyn_cast<llvm::StructType>(IndexedType);
if (STy) {
// Save the original To argument so we can modify it
// insertvalue instruction somewhere).
//
// All inserted insertvalue instructions are inserted before InsertBefore
-Value *BuildSubAggregate(Value *From, const unsigned *idx_begin,
- const unsigned *idx_end, Instruction *InsertBefore) {
+static Value *BuildSubAggregate(Value *From, const unsigned *idx_begin,
+ const unsigned *idx_end,
+ Instruction *InsertBefore) {
assert(InsertBefore && "Must have someplace to insert!");
const Type *IndexedType = ExtractValueInst::getIndexedType(From->getType(),
idx_begin,
if (idx_begin == idx_end)
return V;
// We have indices, so V should have an indexable type
- assert((isa<StructType>(V->getType()) || isa<ArrayType>(V->getType()))
+ assert((V->getType()->isStructTy() || V->getType()->isArrayTy())
&& "Not looking at a struct or array?");
assert(ExtractValueInst::getIndexedType(V->getType(), idx_begin, idx_end)
&& "Invalid indices for type?");
const CompositeType *PTy = cast<CompositeType>(V->getType());
-
+
if (isa<UndefValue>(V))
return UndefValue::get(ExtractValueInst::getIndexedType(PTy,
idx_begin,
idx_end));
else if (isa<ConstantAggregateZero>(V))
return Constant::getNullValue(ExtractValueInst::getIndexedType(PTy,
- idx_begin,
- idx_end));
+ idx_begin,
+ idx_end));
else if (Constant *C = dyn_cast<Constant>(V)) {
if (isa<ConstantArray>(C) || isa<ConstantStruct>(C))
// Recursively process this constant
- return FindInsertedValue(C->getOperand(*idx_begin), idx_begin + 1, idx_end,
- InsertBefore);
+ return FindInsertedValue(C->getOperand(*idx_begin), idx_begin + 1,
+ idx_end, InsertBefore);
} else if (InsertValueInst *I = dyn_cast<InsertValueInst>(V)) {
// Loop the indices for the insertvalue instruction in parallel with the
// requested indices
/// GetConstantStringInfo - This function computes the length of a
/// null-terminated C string pointed to by V. If successful, it returns true
/// and returns the string in Str. If unsuccessful, it returns false.
-bool llvm::GetConstantStringInfo(Value *V, std::string &Str, uint64_t Offset,
+bool llvm::GetConstantStringInfo(const Value *V, std::string &Str,
+ uint64_t Offset,
bool StopAtNul) {
// If V is NULL then return false;
if (V == NULL) return false;
// Look through bitcast instructions.
- if (BitCastInst *BCI = dyn_cast<BitCastInst>(V))
+ if (const BitCastInst *BCI = dyn_cast<BitCastInst>(V))
return GetConstantStringInfo(BCI->getOperand(0), Str, Offset, StopAtNul);
// If the value is not a GEP instruction nor a constant expression with a
// GEP instruction, then return false because ConstantArray can't occur
// any other way
- User *GEP = 0;
- if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(V)) {
+ const User *GEP = 0;
+ if (const GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(V)) {
GEP = GEPI;
- } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
+ } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
if (CE->getOpcode() == Instruction::BitCast)
return GetConstantStringInfo(CE->getOperand(0), Str, Offset, StopAtNul);
if (CE->getOpcode() != Instruction::GetElementPtr)
// Make sure the index-ee is a pointer to array of i8.
const PointerType *PT = cast<PointerType>(GEP->getOperand(0)->getType());
const ArrayType *AT = dyn_cast<ArrayType>(PT->getElementType());
- if (AT == 0 || AT->getElementType() != Type::Int8Ty)
+ if (AT == 0 || !AT->getElementType()->isIntegerTy(8))
return false;
// Check to make sure that the first operand of the GEP is an integer and
// has value 0 so that we are sure we're indexing into the initializer.
- ConstantInt *FirstIdx = dyn_cast<ConstantInt>(GEP->getOperand(1));
+ const ConstantInt *FirstIdx = dyn_cast<ConstantInt>(GEP->getOperand(1));
if (FirstIdx == 0 || !FirstIdx->isZero())
return false;
// into the array. If this occurs, we can't say anything meaningful about
// the string.
uint64_t StartIdx = 0;
- if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2)))
+ if (const ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2)))
StartIdx = CI->getZExtValue();
else
return false;
// The GEP instruction, constant or instruction, must reference a global
// variable that is a constant and is initialized. The referenced constant
// initializer is the array that we'll use for optimization.
- GlobalVariable* GV = dyn_cast<GlobalVariable>(V);
- if (!GV || !GV->isConstant() || !GV->hasInitializer())
+ const GlobalVariable* GV = dyn_cast<GlobalVariable>(V);
+ if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer())
return false;
- Constant *GlobalInit = GV->getInitializer();
+ const Constant *GlobalInit = GV->getInitializer();
// Handle the ConstantAggregateZero case
if (isa<ConstantAggregateZero>(GlobalInit)) {
}
// Must be a Constant Array
- ConstantArray *Array = dyn_cast<ConstantArray>(GlobalInit);
- if (Array == 0 || Array->getType()->getElementType() != Type::Int8Ty)
+ const ConstantArray *Array = dyn_cast<ConstantArray>(GlobalInit);
+ if (Array == 0 || !Array->getType()->getElementType()->isIntegerTy(8))
return false;
// Get the number of elements in the array
// to in the array.
Str.reserve(NumElts-Offset);
for (unsigned i = Offset; i != NumElts; ++i) {
- Constant *Elt = Array->getOperand(i);
- ConstantInt *CI = dyn_cast<ConstantInt>(Elt);
+ const Constant *Elt = Array->getOperand(i);
+ const ConstantInt *CI = dyn_cast<ConstantInt>(Elt);
if (!CI) // This array isn't suitable, non-int initializer.
return false;
if (StopAtNul && CI->isZero())
// The array isn't null terminated, but maybe this is a memcpy, not a strcpy.
return true;
}
+
+// These next two are very similar to the above, but also look through PHI
+// nodes.
+// TODO: See if we can integrate these two together.
+
+/// GetStringLengthH - If we can compute the length of the string pointed to by
+/// the specified pointer, return 'len+1'. If we can't, return 0.
+static uint64_t GetStringLengthH(Value *V, SmallPtrSet<PHINode*, 32> &PHIs) {
+ // Look through noop bitcast instructions.
+ if (BitCastInst *BCI = dyn_cast<BitCastInst>(V))
+ return GetStringLengthH(BCI->getOperand(0), PHIs);
+
+ // If this is a PHI node, there are two cases: either we have already seen it
+ // or we haven't.
+ if (PHINode *PN = dyn_cast<PHINode>(V)) {
+ if (!PHIs.insert(PN))
+ return ~0ULL; // already in the set.
+
+ // If it was new, see if all the input strings are the same length.
+ uint64_t LenSoFar = ~0ULL;
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
+ uint64_t Len = GetStringLengthH(PN->getIncomingValue(i), PHIs);
+ if (Len == 0) return 0; // Unknown length -> unknown.
+
+ if (Len == ~0ULL) continue;
+
+ if (Len != LenSoFar && LenSoFar != ~0ULL)
+ return 0; // Disagree -> unknown.
+ LenSoFar = Len;
+ }
+
+ // Success, all agree.
+ return LenSoFar;
+ }
+
+ // strlen(select(c,x,y)) -> strlen(x) ^ strlen(y)
+ if (SelectInst *SI = dyn_cast<SelectInst>(V)) {
+ uint64_t Len1 = GetStringLengthH(SI->getTrueValue(), PHIs);
+ if (Len1 == 0) return 0;
+ uint64_t Len2 = GetStringLengthH(SI->getFalseValue(), PHIs);
+ if (Len2 == 0) return 0;
+ if (Len1 == ~0ULL) return Len2;
+ if (Len2 == ~0ULL) return Len1;
+ if (Len1 != Len2) return 0;
+ return Len1;
+ }
+
+ // If the value is not a GEP instruction nor a constant expression with a
+ // GEP instruction, then return unknown.
+ User *GEP = 0;
+ if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(V)) {
+ GEP = GEPI;
+ } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
+ if (CE->getOpcode() != Instruction::GetElementPtr)
+ return 0;
+ GEP = CE;
+ } else {
+ return 0;
+ }
+
+ // Make sure the GEP has exactly three arguments.
+ if (GEP->getNumOperands() != 3)
+ return 0;
+
+ // Check to make sure that the first operand of the GEP is an integer and
+ // has value 0 so that we are sure we're indexing into the initializer.
+ if (ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(1))) {
+ if (!Idx->isZero())
+ return 0;
+ } else
+ return 0;
+
+ // If the second index isn't a ConstantInt, then this is a variable index
+ // into the array. If this occurs, we can't say anything meaningful about
+ // the string.
+ uint64_t StartIdx = 0;
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2)))
+ StartIdx = CI->getZExtValue();
+ else
+ return 0;
+
+ // The GEP instruction, constant or instruction, must reference a global
+ // variable that is a constant and is initialized. The referenced constant
+ // initializer is the array that we'll use for optimization.
+ GlobalVariable* GV = dyn_cast<GlobalVariable>(GEP->getOperand(0));
+ if (!GV || !GV->isConstant() || !GV->hasInitializer() ||
+ GV->mayBeOverridden())
+ return 0;
+ Constant *GlobalInit = GV->getInitializer();
+
+ // Handle the ConstantAggregateZero case, which is a degenerate case. The
+ // initializer is constant zero so the length of the string must be zero.
+ if (isa<ConstantAggregateZero>(GlobalInit))
+ return 1; // Len = 0 offset by 1.
+
+ // Must be a Constant Array
+ ConstantArray *Array = dyn_cast<ConstantArray>(GlobalInit);
+ if (!Array || !Array->getType()->getElementType()->isIntegerTy(8))
+ return false;
+
+ // Get the number of elements in the array
+ uint64_t NumElts = Array->getType()->getNumElements();
+
+ // Traverse the constant array from StartIdx (derived above) which is
+ // the place the GEP refers to in the array.
+ for (unsigned i = StartIdx; i != NumElts; ++i) {
+ Constant *Elt = Array->getOperand(i);
+ ConstantInt *CI = dyn_cast<ConstantInt>(Elt);
+ if (!CI) // This array isn't suitable, non-int initializer.
+ return 0;
+ if (CI->isZero())
+ return i-StartIdx+1; // We found end of string, success!
+ }
+
+ return 0; // The array isn't null terminated, conservatively return 'unknown'.
+}
+
+/// GetStringLength - If we can compute the length of the string pointed to by
+/// the specified pointer, return 'len+1'. If we can't, return 0.
+uint64_t llvm::GetStringLength(Value *V) {
+ if (!V->getType()->isPointerTy()) return 0;
+
+ SmallPtrSet<PHINode*, 32> PHIs;
+ uint64_t Len = GetStringLengthH(V, PHIs);
+ // If Len is ~0ULL, we had an infinite phi cycle: this is dead code, so return
+ // an empty string as a length.
+ return Len == ~0ULL ? 1 : Len;
+}
projects / oota-llvm.git / blobdiff