//===----------------------------------------------------------------------===//
#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Constants.h"
#include "llvm/Instructions.h"
#include "llvm/GlobalVariable.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/MathExtras.h"
+#include "llvm/Support/PatternMatch.h"
+#include "llvm/ADT/SmallPtrSet.h"
#include <cstring>
using namespace llvm;
+using namespace llvm::PatternMatch;
+
+const unsigned MaxDepth = 6;
+
+/// getBitWidth - Returns the bitwidth of the given scalar or pointer type (if
+/// unknown returns 0). For vector types, returns the element type's bitwidth.
+static unsigned getBitWidth(Type *Ty, const TargetData *TD) {
+ if (unsigned BitWidth = Ty->getScalarSizeInBits())
+ return BitWidth;
+ assert(isa<PointerType>(Ty) && "Expected a pointer type!");
+ return TD ? TD->getPointerSizeInBits() : 0;
+}
/// ComputeMaskedBits - Determine which of the bits specified in Mask are
/// known to be either zero or one and return them in the KnownZero/KnownOne
void llvm::ComputeMaskedBits(Value *V, const APInt &Mask,
APInt &KnownZero, APInt &KnownOne,
const TargetData *TD, unsigned Depth) {
- const unsigned MaxDepth = 6;
assert(V && "No Value?");
assert(Depth <= MaxDepth && "Limit Search Depth");
unsigned BitWidth = Mask.getBitWidth();
- assert((V->getType()->isIntOrIntVector() || isa<PointerType>(V->getType())) &&
- "Not integer or pointer type!");
+ assert((V->getType()->isIntOrIntVectorTy() || V->getType()->isPointerTy())
+ && "Not integer or pointer type!");
assert((!TD ||
TD->getTypeSizeInBits(V->getType()->getScalarType()) == BitWidth) &&
- (!V->getType()->isIntOrIntVector() ||
+ (!V->getType()->isIntOrIntVectorTy() ||
V->getType()->getScalarSizeInBits() == BitWidth) &&
KnownZero.getBitWidth() == BitWidth &&
KnownOne.getBitWidth() == BitWidth &&
// Null and aggregate-zero are all-zeros.
if (isa<ConstantPointerNull>(V) ||
isa<ConstantAggregateZero>(V)) {
- KnownOne.clear();
+ KnownOne.clearAllBits();
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();
+ KnownZero.setAllBits(); KnownOne.setAllBits();
for (unsigned i = 0, e = CV->getNumOperands(); i != e; ++i) {
APInt KnownZero2(BitWidth, 0), KnownOne2(BitWidth, 0);
ComputeMaskedBits(CV->getOperand(i), Mask, KnownZero2, KnownOne2,
if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
unsigned Align = GV->getAlignment();
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 (GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV)) {
+ Type *ObjectType = GVar->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 (!GVar->isDeclaration() && !GVar->mayBeOverridden())
+ Align = TD->getPreferredAlignment(GVar);
+ else
+ Align = TD->getABITypeAlignment(ObjectType);
+ }
}
if (Align > 0)
KnownZero = Mask & APInt::getLowBitsSet(BitWidth,
CountTrailingZeros_32(Align));
else
- KnownZero.clear();
- KnownOne.clear();
+ KnownZero.clearAllBits();
+ KnownOne.clearAllBits();
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();
+ KnownZero.clearAllBits(); KnownOne.clearAllBits();
} else {
ComputeMaskedBits(GA->getAliasee(), Mask, KnownZero, KnownOne,
TD, Depth+1);
}
return;
}
+
+ if (Argument *A = dyn_cast<Argument>(V)) {
+ // Get alignment information off byval arguments if specified in the IR.
+ if (A->hasByValAttr())
+ if (unsigned Align = A->getParamAlignment())
+ KnownZero = Mask & APInt::getLowBitsSet(BitWidth,
+ CountTrailingZeros_32(Align));
+ return;
+ }
- KnownZero.clear(); KnownOne.clear(); // Start out not knowing anything.
+ // Start out not knowing anything.
+ KnownZero.clearAllBits(); KnownOne.clearAllBits();
if (Depth == MaxDepth || Mask == 0)
return; // Limit search depth.
ComputeMaskedBits(I->getOperand(1), Mask2, KnownZero, KnownOne, TD,Depth+1);
ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero2, KnownOne2, TD,
Depth+1);
- assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
- assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
-
+ assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
+ assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
+
+ bool isKnownNegative = false;
+ bool isKnownNonNegative = false;
+ // If the multiplication is known not to overflow, compute the sign bit.
+ if (Mask.isNegative() &&
+ cast<OverflowingBinaryOperator>(I)->hasNoSignedWrap()) {
+ Value *Op1 = I->getOperand(1), *Op2 = I->getOperand(0);
+ if (Op1 == Op2) {
+ // The product of a number with itself is non-negative.
+ isKnownNonNegative = true;
+ } else {
+ bool isKnownNonNegative1 = KnownZero.isNegative();
+ bool isKnownNonNegative2 = KnownZero2.isNegative();
+ bool isKnownNegative1 = KnownOne.isNegative();
+ bool isKnownNegative2 = KnownOne2.isNegative();
+ // The product of two numbers with the same sign is non-negative.
+ isKnownNonNegative = (isKnownNegative1 && isKnownNegative2) ||
+ (isKnownNonNegative1 && isKnownNonNegative2);
+ // The product of a negative number and a non-negative number is either
+ // negative or zero.
+ if (!isKnownNonNegative)
+ isKnownNegative = (isKnownNegative1 && isKnownNonNegative2 &&
+ isKnownNonZero(Op2, TD, Depth)) ||
+ (isKnownNegative2 && isKnownNonNegative1 &&
+ isKnownNonZero(Op1, TD, Depth));
+ }
+ }
+
// If low bits are zero in either operand, output low known-0 bits.
// Also compute a conserative estimate for high known-0 bits.
// More trickiness is possible, but this is sufficient for the
// interesting case of alignment computation.
- KnownOne.clear();
+ KnownOne.clearAllBits();
unsigned TrailZ = KnownZero.countTrailingOnes() +
KnownZero2.countTrailingOnes();
unsigned LeadZ = std::max(KnownZero.countLeadingOnes() +
KnownZero = APInt::getLowBitsSet(BitWidth, TrailZ) |
APInt::getHighBitsSet(BitWidth, LeadZ);
KnownZero &= Mask;
+
+ // Only make use of no-wrap flags if we failed to compute the sign bit
+ // directly. This matters if the multiplication always overflows, in
+ // which case we prefer to follow the result of the direct computation,
+ // though as the program is invoking undefined behaviour we can choose
+ // whatever we like here.
+ if (isKnownNonNegative && !KnownOne.isNegative())
+ KnownZero.setBit(BitWidth - 1);
+ else if (isKnownNegative && !KnownZero.isNegative())
+ KnownOne.setBit(BitWidth - 1);
+
return;
}
case Instruction::UDiv: {
AllOnes, KnownZero2, KnownOne2, TD, Depth+1);
unsigned LeadZ = KnownZero2.countLeadingOnes();
- KnownOne2.clear();
- KnownZero2.clear();
+ KnownOne2.clearAllBits();
+ KnownZero2.clearAllBits();
ComputeMaskedBits(I->getOperand(1),
AllOnes, KnownZero2, KnownOne2, TD, Depth+1);
unsigned RHSUnknownLeadingOnes = KnownOne2.countLeadingZeros();
// FALL THROUGH and handle them the same as zext/trunc.
case Instruction::ZExt:
case Instruction::Trunc: {
- const Type *SrcTy = I->getOperand(0)->getType();
+ Type *SrcTy = I->getOperand(0)->getType();
unsigned SrcBitWidth;
// Note that we handle pointer operands here because of inttoptr/ptrtoint
// which fall through here.
- if (isa<PointerType>(SrcTy))
+ if (SrcTy->isPointerTy())
SrcBitWidth = TD->getTypeSizeInBits(SrcTy);
else
SrcBitWidth = SrcTy->getScalarSizeInBits();
- APInt MaskIn(Mask);
- MaskIn.zextOrTrunc(SrcBitWidth);
- KnownZero.zextOrTrunc(SrcBitWidth);
- KnownOne.zextOrTrunc(SrcBitWidth);
+ APInt MaskIn = Mask.zextOrTrunc(SrcBitWidth);
+ KnownZero = KnownZero.zextOrTrunc(SrcBitWidth);
+ KnownOne = KnownOne.zextOrTrunc(SrcBitWidth);
ComputeMaskedBits(I->getOperand(0), MaskIn, KnownZero, KnownOne, TD,
Depth+1);
- KnownZero.zextOrTrunc(BitWidth);
- KnownOne.zextOrTrunc(BitWidth);
+ KnownZero = KnownZero.zextOrTrunc(BitWidth);
+ KnownOne = KnownOne.zextOrTrunc(BitWidth);
// Any top bits are known to be zero.
if (BitWidth > SrcBitWidth)
KnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth);
return;
}
case Instruction::BitCast: {
- const Type *SrcTy = I->getOperand(0)->getType();
- if ((SrcTy->isInteger() || isa<PointerType>(SrcTy)) &&
+ Type *SrcTy = I->getOperand(0)->getType();
+ if ((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
// TODO: For now, not handling conversions like:
// (bitcast i64 %x to <2 x i32>)
- !isa<VectorType>(I->getType())) {
+ !I->getType()->isVectorTy()) {
ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, TD,
Depth+1);
return;
// Compute the bits in the result that are not present in the input.
unsigned SrcBitWidth = I->getOperand(0)->getType()->getScalarSizeInBits();
- APInt MaskIn(Mask);
- MaskIn.trunc(SrcBitWidth);
- KnownZero.trunc(SrcBitWidth);
- KnownOne.trunc(SrcBitWidth);
+ APInt MaskIn = Mask.trunc(SrcBitWidth);
+ KnownZero = KnownZero.trunc(SrcBitWidth);
+ KnownOne = KnownOne.trunc(SrcBitWidth);
ComputeMaskedBits(I->getOperand(0), MaskIn, KnownZero, KnownOne, TD,
Depth+1);
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
- KnownZero.zext(BitWidth);
- KnownOne.zext(BitWidth);
+ KnownZero = KnownZero.zext(BitWidth);
+ KnownOne = KnownOne.zext(BitWidth);
// If the sign bit of the input is known set or clear, then we know the
// top bits of the result.
// (ashr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0
if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
// Compute the new bits that are at the top now.
- uint64_t ShiftAmt = SA->getLimitedValue(BitWidth);
+ uint64_t ShiftAmt = SA->getLimitedValue(BitWidth-1);
// Signed shift right.
APInt Mask2(Mask.shl(ShiftAmt));
KnownZero |= LHSKnownZero & Mask;
KnownOne |= LHSKnownOne & Mask;
}
+
+ // Are we still trying to solve for the sign bit?
+ if (Mask.isNegative() && !KnownZero.isNegative() && !KnownOne.isNegative()){
+ OverflowingBinaryOperator *OBO = cast<OverflowingBinaryOperator>(I);
+ if (OBO->hasNoSignedWrap()) {
+ if (I->getOpcode() == Instruction::Add) {
+ // Adding two positive numbers can't wrap into negative
+ if (LHSKnownZero.isNegative() && KnownZero2.isNegative())
+ KnownZero |= APInt::getSignBit(BitWidth);
+ // and adding two negative numbers can't wrap into positive.
+ else if (LHSKnownOne.isNegative() && KnownOne2.isNegative())
+ KnownOne |= APInt::getSignBit(BitWidth);
+ } else {
+ // Subtracting a negative number from a positive one can't wrap
+ if (LHSKnownZero.isNegative() && KnownOne2.isNegative())
+ KnownZero |= APInt::getSignBit(BitWidth);
+ // neither can subtracting a positive number from a negative one.
+ else if (LHSKnownOne.isNegative() && KnownZero2.isNegative())
+ KnownOne |= APInt::getSignBit(BitWidth);
+ }
+ }
+ }
+
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;
+
+ KnownZero &= Mask;
+ KnownOne &= Mask;
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
}
}
+
+ // The sign bit is the LHS's sign bit, except when the result of the
+ // remainder is zero.
+ if (Mask.isNegative() && KnownZero.isNonNegative()) {
+ APInt Mask2 = APInt::getSignBit(BitWidth);
+ APInt LHSKnownZero(BitWidth, 0), LHSKnownOne(BitWidth, 0);
+ ComputeMaskedBits(I->getOperand(0), Mask2, LHSKnownZero, LHSKnownOne, TD,
+ Depth+1);
+ // If it's known zero, our sign bit is also zero.
+ if (LHSKnownZero.isNegative())
+ KnownZero |= LHSKnownZero;
+ }
+
break;
case Instruction::URem: {
if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) {
unsigned Leaders = std::max(KnownZero.countLeadingOnes(),
KnownZero2.countLeadingOnes());
- KnownOne.clear();
+ KnownOne.clearAllBits();
KnownZero = APInt::getHighBitsSet(BitWidth, Leaders) & Mask;
break;
}
gep_type_iterator GTI = gep_type_begin(I);
for (unsigned i = 1, e = I->getNumOperands(); i != e; ++i, ++GTI) {
Value *Index = I->getOperand(i);
- if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
+ if (StructType *STy = dyn_cast<StructType>(*GTI)) {
// Handle struct member offset arithmetic.
if (!TD) return;
const StructLayout *SL = TD->getStructLayout(STy);
CountTrailingZeros_64(Offset));
} else {
// Handle array index arithmetic.
- const Type *IndexedTy = GTI.getIndexedType();
+ Type *IndexedTy = GTI.getIndexedType();
if (!IndexedTy->isSized()) return;
unsigned GEPOpiBits = Index->getType()->getScalarSizeInBits();
uint64_t TypeSize = TD ? TD->getTypeAllocSize(IndexedTy) : 1;
}
}
+ // Unreachable blocks may have zero-operand PHI nodes.
+ if (P->getNumIncomingValues() == 0)
+ return;
+
// 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) {
+ // Skip if every incoming value references to ourself.
+ if (P->hasConstantValue() == P)
+ break;
+
KnownZero = APInt::getAllOnesValue(BitWidth);
KnownOne = APInt::getAllOnesValue(BitWidth);
for (unsigned i = 0, e = P->getNumIncomingValues(); i != e; ++i) {
KnownZero = APInt::getHighBitsSet(BitWidth, BitWidth - LowBits);
break;
}
+ case Intrinsic::x86_sse42_crc32_64_8:
+ case Intrinsic::x86_sse42_crc32_64_64:
+ KnownZero = APInt::getHighBitsSet(64, 32);
+ break;
}
}
break;
}
}
+/// ComputeSignBit - Determine whether the sign bit is known to be zero or
+/// one. Convenience wrapper around ComputeMaskedBits.
+void llvm::ComputeSignBit(Value *V, bool &KnownZero, bool &KnownOne,
+ const TargetData *TD, unsigned Depth) {
+ unsigned BitWidth = getBitWidth(V->getType(), TD);
+ if (!BitWidth) {
+ KnownZero = false;
+ KnownOne = false;
+ return;
+ }
+ APInt ZeroBits(BitWidth, 0);
+ APInt OneBits(BitWidth, 0);
+ ComputeMaskedBits(V, APInt::getSignBit(BitWidth), ZeroBits, OneBits, TD,
+ Depth);
+ KnownOne = OneBits[BitWidth - 1];
+ KnownZero = ZeroBits[BitWidth - 1];
+}
+
+/// isPowerOfTwo - Return true if the given value is known to have exactly one
+/// bit set when defined. For vectors return true if every element is known to
+/// be a power of two when defined. Supports values with integer or pointer
+/// types and vectors of integers.
+bool llvm::isPowerOfTwo(Value *V, const TargetData *TD, bool OrZero,
+ unsigned Depth) {
+ if (Constant *C = dyn_cast<Constant>(V)) {
+ if (C->isNullValue())
+ return OrZero;
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(C))
+ return CI->getValue().isPowerOf2();
+ // TODO: Handle vector constants.
+ }
+
+ // 1 << X is clearly a power of two if the one is not shifted off the end. If
+ // it is shifted off the end then the result is undefined.
+ if (match(V, m_Shl(m_One(), m_Value())))
+ return true;
+
+ // (signbit) >>l X is clearly a power of two if the one is not shifted off the
+ // bottom. If it is shifted off the bottom then the result is undefined.
+ if (match(V, m_LShr(m_SignBit(), m_Value())))
+ return true;
+
+ // The remaining tests are all recursive, so bail out if we hit the limit.
+ if (Depth++ == MaxDepth)
+ return false;
+
+ Value *X = 0, *Y = 0;
+ // A shift of a power of two is a power of two or zero.
+ if (OrZero && (match(V, m_Shl(m_Value(X), m_Value())) ||
+ match(V, m_Shr(m_Value(X), m_Value()))))
+ return isPowerOfTwo(X, TD, /*OrZero*/true, Depth);
+
+ if (ZExtInst *ZI = dyn_cast<ZExtInst>(V))
+ return isPowerOfTwo(ZI->getOperand(0), TD, OrZero, Depth);
+
+ if (SelectInst *SI = dyn_cast<SelectInst>(V))
+ return isPowerOfTwo(SI->getTrueValue(), TD, OrZero, Depth) &&
+ isPowerOfTwo(SI->getFalseValue(), TD, OrZero, Depth);
+
+ if (OrZero && match(V, m_And(m_Value(X), m_Value(Y)))) {
+ // A power of two and'd with anything is a power of two or zero.
+ if (isPowerOfTwo(X, TD, /*OrZero*/true, Depth) ||
+ isPowerOfTwo(Y, TD, /*OrZero*/true, Depth))
+ return true;
+ // X & (-X) is always a power of two or zero.
+ if (match(X, m_Neg(m_Specific(Y))) || match(Y, m_Neg(m_Specific(X))))
+ return true;
+ return false;
+ }
+
+ // An exact divide or right shift can only shift off zero bits, so the result
+ // is a power of two only if the first operand is a power of two and not
+ // copying a sign bit (sdiv int_min, 2).
+ if (match(V, m_LShr(m_Value(), m_Value())) ||
+ match(V, m_UDiv(m_Value(), m_Value()))) {
+ PossiblyExactOperator *PEO = cast<PossiblyExactOperator>(V);
+ if (PEO->isExact())
+ return isPowerOfTwo(PEO->getOperand(0), TD, OrZero, Depth);
+ }
+
+ return false;
+}
+
+/// isKnownNonZero - Return true if the given value is known to be non-zero
+/// when defined. For vectors return true if every element is known to be
+/// non-zero when defined. Supports values with integer or pointer type and
+/// vectors of integers.
+bool llvm::isKnownNonZero(Value *V, const TargetData *TD, unsigned Depth) {
+ if (Constant *C = dyn_cast<Constant>(V)) {
+ if (C->isNullValue())
+ return false;
+ if (isa<ConstantInt>(C))
+ // Must be non-zero due to null test above.
+ return true;
+ // TODO: Handle vectors
+ return false;
+ }
+
+ // The remaining tests are all recursive, so bail out if we hit the limit.
+ if (Depth++ >= MaxDepth)
+ return false;
+
+ unsigned BitWidth = getBitWidth(V->getType(), TD);
+
+ // X | Y != 0 if X != 0 or Y != 0.
+ Value *X = 0, *Y = 0;
+ if (match(V, m_Or(m_Value(X), m_Value(Y))))
+ return isKnownNonZero(X, TD, Depth) || isKnownNonZero(Y, TD, Depth);
+
+ // ext X != 0 if X != 0.
+ if (isa<SExtInst>(V) || isa<ZExtInst>(V))
+ return isKnownNonZero(cast<Instruction>(V)->getOperand(0), TD, Depth);
+
+ // shl X, Y != 0 if X is odd. Note that the value of the shift is undefined
+ // if the lowest bit is shifted off the end.
+ if (BitWidth && match(V, m_Shl(m_Value(X), m_Value(Y)))) {
+ // shl nuw can't remove any non-zero bits.
+ OverflowingBinaryOperator *BO = cast<OverflowingBinaryOperator>(V);
+ if (BO->hasNoUnsignedWrap())
+ return isKnownNonZero(X, TD, Depth);
+
+ APInt KnownZero(BitWidth, 0);
+ APInt KnownOne(BitWidth, 0);
+ ComputeMaskedBits(X, APInt(BitWidth, 1), KnownZero, KnownOne, TD, Depth);
+ if (KnownOne[0])
+ return true;
+ }
+ // shr X, Y != 0 if X is negative. Note that the value of the shift is not
+ // defined if the sign bit is shifted off the end.
+ else if (match(V, m_Shr(m_Value(X), m_Value(Y)))) {
+ // shr exact can only shift out zero bits.
+ PossiblyExactOperator *BO = cast<PossiblyExactOperator>(V);
+ if (BO->isExact())
+ return isKnownNonZero(X, TD, Depth);
+
+ bool XKnownNonNegative, XKnownNegative;
+ ComputeSignBit(X, XKnownNonNegative, XKnownNegative, TD, Depth);
+ if (XKnownNegative)
+ return true;
+ }
+ // div exact can only produce a zero if the dividend is zero.
+ else if (match(V, m_IDiv(m_Value(X), m_Value()))) {
+ PossiblyExactOperator *BO = cast<PossiblyExactOperator>(V);
+ if (BO->isExact())
+ return isKnownNonZero(X, TD, Depth);
+ }
+ // X + Y.
+ else if (match(V, m_Add(m_Value(X), m_Value(Y)))) {
+ bool XKnownNonNegative, XKnownNegative;
+ bool YKnownNonNegative, YKnownNegative;
+ ComputeSignBit(X, XKnownNonNegative, XKnownNegative, TD, Depth);
+ ComputeSignBit(Y, YKnownNonNegative, YKnownNegative, TD, Depth);
+
+ // If X and Y are both non-negative (as signed values) then their sum is not
+ // zero unless both X and Y are zero.
+ if (XKnownNonNegative && YKnownNonNegative)
+ if (isKnownNonZero(X, TD, Depth) || isKnownNonZero(Y, TD, Depth))
+ return true;
+
+ // If X and Y are both negative (as signed values) then their sum is not
+ // zero unless both X and Y equal INT_MIN.
+ if (BitWidth && XKnownNegative && YKnownNegative) {
+ APInt KnownZero(BitWidth, 0);
+ APInt KnownOne(BitWidth, 0);
+ APInt Mask = APInt::getSignedMaxValue(BitWidth);
+ // The sign bit of X is set. If some other bit is set then X is not equal
+ // to INT_MIN.
+ ComputeMaskedBits(X, Mask, KnownZero, KnownOne, TD, Depth);
+ if ((KnownOne & Mask) != 0)
+ return true;
+ // The sign bit of Y is set. If some other bit is set then Y is not equal
+ // to INT_MIN.
+ ComputeMaskedBits(Y, Mask, KnownZero, KnownOne, TD, Depth);
+ if ((KnownOne & Mask) != 0)
+ return true;
+ }
+
+ // The sum of a non-negative number and a power of two is not zero.
+ if (XKnownNonNegative && isPowerOfTwo(Y, TD, /*OrZero*/false, Depth))
+ return true;
+ if (YKnownNonNegative && isPowerOfTwo(X, TD, /*OrZero*/false, Depth))
+ return true;
+ }
+ // X * Y.
+ else if (match(V, m_Mul(m_Value(X), m_Value(Y)))) {
+ OverflowingBinaryOperator *BO = cast<OverflowingBinaryOperator>(V);
+ // If X and Y are non-zero then so is X * Y as long as the multiplication
+ // does not overflow.
+ if ((BO->hasNoSignedWrap() || BO->hasNoUnsignedWrap()) &&
+ isKnownNonZero(X, TD, Depth) && isKnownNonZero(Y, TD, Depth))
+ return true;
+ }
+ // (C ? X : Y) != 0 if X != 0 and Y != 0.
+ else if (SelectInst *SI = dyn_cast<SelectInst>(V)) {
+ if (isKnownNonZero(SI->getTrueValue(), TD, Depth) &&
+ isKnownNonZero(SI->getFalseValue(), TD, Depth))
+ return true;
+ }
+
+ if (!BitWidth) return false;
+ APInt KnownZero(BitWidth, 0);
+ APInt KnownOne(BitWidth, 0);
+ ComputeMaskedBits(V, APInt::getAllOnesValue(BitWidth), KnownZero, KnownOne,
+ TD, Depth);
+ return KnownOne != 0;
+}
+
/// 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.
///
unsigned llvm::ComputeNumSignBits(Value *V, const TargetData *TD,
unsigned Depth) {
- assert((TD || V->getType()->isIntOrIntVector()) &&
+ assert((TD || V->getType()->isIntOrIntVectorTy()) &&
"ComputeNumSignBits requires a TargetData object to operate "
"on non-integer values!");
- const Type *Ty = V->getType();
+ Type *Ty = V->getType();
unsigned TyBits = TD ? TD->getTypeSizeInBits(V->getType()->getScalarType()) :
Ty->getScalarSizeInBits();
unsigned Tmp, Tmp2;
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:
Tmp += C->getZExtValue();
if (Tmp > TyBits) Tmp = TyBits;
}
+ // vector ashr X, <C, C, C, C> -> adds C sign bits
+ if (ConstantVector *C = dyn_cast<ConstantVector>(U->getOperand(1))) {
+ if (ConstantInt *CI = dyn_cast_or_null<ConstantInt>(C->getSplatValue())) {
+ Tmp += CI->getZExtValue();
+ if (Tmp > TyBits) Tmp = TyBits;
+ }
+ }
return Tmp;
case Instruction::Shl:
if (ConstantInt *C = dyn_cast<ConstantInt>(U->getOperand(1))) {
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.
assert(V && "No Value?");
assert(Depth <= MaxDepth && "Limit Search Depth");
- assert(V->getType()->isInteger() && "Not integer or pointer type!");
+ assert(V->getType()->isIntegerTy() && "Not integer or pointer type!");
- const Type *T = V->getType();
+ Type *T = V->getType();
ConstantInt *CI = dyn_cast<ConstantInt>(V);
// 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));
+ APInt API(Op1Int.getBitWidth(), 0);
+ API.setBit(BitToSet);
+ Op1 = ConstantInt::get(V->getContext(), API);
}
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 (ComputeMultiple(Op0, Base, Mul0, LookThroughSExt, Depth+1)) {
+ if (Constant *Op1C = dyn_cast<Constant>(Op1))
+ if (Constant *MulC = dyn_cast<Constant>(Mul0)) {
+ if (Op1C->getType()->getPrimitiveSizeInBits() <
+ MulC->getType()->getPrimitiveSizeInBits())
+ Op1C = ConstantExpr::getZExt(Op1C, MulC->getType());
+ if (Op1C->getType()->getPrimitiveSizeInBits() >
+ MulC->getType()->getPrimitiveSizeInBits())
+ MulC = ConstantExpr::getZExt(MulC, Op1C->getType());
+
+ // V == Base * (Mul0 * Op1), so return (Mul0 * Op1)
+ Multiple = ConstantExpr::getMul(MulC, Op1C);
+ return true;
+ }
if (ConstantInt *Mul0CI = dyn_cast<ConstantInt>(Mul0))
if (Mul0CI->getValue() == 1) {
}
}
- 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;
- }
+ Value *Mul1 = NULL;
+ if (ComputeMultiple(Op1, Base, Mul1, LookThroughSExt, Depth+1)) {
+ if (Constant *Op0C = dyn_cast<Constant>(Op0))
+ if (Constant *MulC = dyn_cast<Constant>(Mul1)) {
+ if (Op0C->getType()->getPrimitiveSizeInBits() <
+ MulC->getType()->getPrimitiveSizeInBits())
+ Op0C = ConstantExpr::getZExt(Op0C, MulC->getType());
+ if (Op0C->getType()->getPrimitiveSizeInBits() >
+ MulC->getType()->getPrimitiveSizeInBits())
+ MulC = ConstantExpr::getZExt(MulC, Op0C->getType());
+
+ // V == Base * (Mul1 * Op0), so return (Mul1 * Op0)
+ Multiple = ConstantExpr::getMul(MulC, Op0C);
+ return true;
+ }
if (ConstantInt *Mul1CI = dyn_cast<ConstantInt>(Mul1))
if (Mul1CI->getValue() == 1) {
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->getName() == "fabsl") return true;
if (F->getName() == "sqrt" || F->getName() == "sqrtf" ||
F->getName() == "sqrtl")
- return CannotBeNegativeZero(CI->getOperand(1), Depth+1);
+ 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) {
- assert(isa<IntegerType>(V->getType()) && "Not an integer value");
-
- 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;
- // FALL THROUGH.
- case Instruction::Add:
- V = GetLinearExpression(BOp->getOperand(0), Scale, Offset, TD);
- Offset += RHSC->getValue();
- return V;
- case Instruction::Mul:
- V = GetLinearExpression(BOp->getOperand(0), Scale, Offset, TD);
- Offset *= RHSC->getValue();
- Scale *= RHSC->getValue();
- return V;
- case Instruction::Shl:
- V = GetLinearExpression(BOp->getOperand(0), Scale, Offset, TD);
- Offset <<= RHSC->getValue().getLimitedValue();
- Scale <<= RHSC->getValue().getLimitedValue();
- return V;
- }
- }
- }
+/// isBytewiseValue - If the specified value can be set by repeating the same
+/// byte in memory, return the i8 value that it is represented with. This is
+/// true for all i8 values obviously, but is also true for i32 0, i32 -1,
+/// i16 0xF0F0, double 0.0 etc. If the value can't be handled with a repeated
+/// byte store (e.g. i16 0x1234), return null.
+Value *llvm::isBytewiseValue(Value *V) {
+ // All byte-wide stores are splatable, even of arbitrary variables.
+ if (V->getType()->isIntegerTy(8)) return V;
+
+ // Handle 'null' ConstantArrayZero etc.
+ if (Constant *C = dyn_cast<Constant>(V))
+ if (C->isNullValue())
+ return Constant::getNullValue(Type::getInt8Ty(V->getContext()));
- // 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);
- Scale.zext(OldWidth);
- Offset.zext(OldWidth);
- return Result;
+ // Constant float and double values can be handled as integer values if the
+ // corresponding integer value is "byteable". An important case is 0.0.
+ if (ConstantFP *CFP = dyn_cast<ConstantFP>(V)) {
+ if (CFP->getType()->isFloatTy())
+ V = ConstantExpr::getBitCast(CFP, Type::getInt32Ty(V->getContext()));
+ if (CFP->getType()->isDoubleTy())
+ V = ConstantExpr::getBitCast(CFP, Type::getInt64Ty(V->getContext()));
+ // Don't handle long double formats, which have strange constraints.
}
- 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) {
- // FIXME: Should limit depth like getUnderlyingObject?
- BaseOffs = 0;
- while (1) {
- // 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;
- }
+ // We can handle constant integers that are power of two in size and a
+ // multiple of 8 bits.
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
+ unsigned Width = CI->getBitWidth();
+ if (isPowerOf2_32(Width) && Width > 8) {
+ // We can handle this value if the recursive binary decomposition is the
+ // same at all levels.
+ APInt Val = CI->getValue();
+ APInt Val2;
+ while (Val.getBitWidth() != 8) {
+ unsigned NextWidth = Val.getBitWidth()/2;
+ Val2 = Val.lshr(NextWidth);
+ Val2 = Val2.trunc(Val.getBitWidth()/2);
+ Val = Val.trunc(Val.getBitWidth()/2);
+
+ // If the top/bottom halves aren't the same, reject it.
+ if (Val != Val2)
+ return 0;
}
- return V;
- }
-
- if (Op->getOpcode() == Instruction::BitCast) {
- V = Op->getOperand(0);
- continue;
+ return ConstantInt::get(V->getContext(), Val);
}
+ }
+
+ // A ConstantArray is splatable if all its members are equal and also
+ // splatable.
+ if (ConstantArray *CA = dyn_cast<ConstantArray>(V)) {
+ if (CA->getNumOperands() == 0)
+ return 0;
- 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;
- }
+ Value *Val = isBytewiseValue(CA->getOperand(0));
+ if (!Val)
+ return 0;
- // 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);
-
- // 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));
- }
+ for (unsigned I = 1, E = CA->getNumOperands(); I != E; ++I)
+ if (CA->getOperand(I-1) != CA->getOperand(I))
+ return 0;
- // Analyze the base pointer next.
- V = GEPOp->getOperand(0);
+ return Val;
}
+
+ // Conceptually, we could handle things like:
+ // %a = zext i8 %X to i16
+ // %b = shl i16 %a, 8
+ // %c = or i16 %a, %b
+ // but until there is an example that actually needs this, it doesn't seem
+ // worth worrying about.
+ return 0;
}
// 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.
-static Value *BuildSubAggregate(Value *From, Value* To, const Type *IndexedType,
+static Value *BuildSubAggregate(Value *From, Value* To, Type *IndexedType,
SmallVector<unsigned, 10> &Idxs,
unsigned IdxSkip,
Instruction *InsertBefore) {
- const llvm::StructType *STy = llvm::dyn_cast<llvm::StructType>(IndexedType);
+ llvm::StructType *STy = llvm::dyn_cast<llvm::StructType>(IndexedType);
if (STy) {
// Save the original To argument so we can modify it
Value *OrigTo = To;
break;
}
}
- // If we succesfully found a value for each of our subaggregates
+ // If we successfully found a value for each of our subaggregates
if (To)
return To;
}
// we might be able to find the complete struct somewhere.
// Find the value that is at that particular spot
- Value *V = FindInsertedValue(From, Idxs.begin(), Idxs.end());
+ Value *V = FindInsertedValue(From, Idxs);
if (!V)
return NULL;
// Insert the value in the new (sub) aggregrate
- return llvm::InsertValueInst::Create(To, V, Idxs.begin() + IdxSkip,
- Idxs.end(), "tmp", InsertBefore);
+ return llvm::InsertValueInst::Create(To, V, makeArrayRef(Idxs).slice(IdxSkip),
+ "tmp", InsertBefore);
}
// This helper takes a nested struct and extracts a part of it (which is again a
// insertvalue instruction somewhere).
//
// All inserted insertvalue instructions are inserted before InsertBefore
-static Value *BuildSubAggregate(Value *From, const unsigned *idx_begin,
- const unsigned *idx_end,
+static Value *BuildSubAggregate(Value *From, ArrayRef<unsigned> idx_range,
Instruction *InsertBefore) {
assert(InsertBefore && "Must have someplace to insert!");
- const Type *IndexedType = ExtractValueInst::getIndexedType(From->getType(),
- idx_begin,
- idx_end);
+ Type *IndexedType = ExtractValueInst::getIndexedType(From->getType(),
+ idx_range);
Value *To = UndefValue::get(IndexedType);
- SmallVector<unsigned, 10> Idxs(idx_begin, idx_end);
+ SmallVector<unsigned, 10> Idxs(idx_range.begin(), idx_range.end());
unsigned IdxSkip = Idxs.size();
return BuildSubAggregate(From, To, IndexedType, Idxs, IdxSkip, InsertBefore);
///
/// If InsertBefore is not null, this function will duplicate (modified)
/// insertvalues when a part of a nested struct is extracted.
-Value *llvm::FindInsertedValue(Value *V, const unsigned *idx_begin,
- const unsigned *idx_end, Instruction *InsertBefore) {
+Value *llvm::FindInsertedValue(Value *V, ArrayRef<unsigned> idx_range,
+ Instruction *InsertBefore) {
// Nothing to index? Just return V then (this is useful at the end of our
// recursion)
- if (idx_begin == idx_end)
+ if (idx_range.empty())
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)
+ assert(ExtractValueInst::getIndexedType(V->getType(), idx_range)
&& "Invalid indices for type?");
- const CompositeType *PTy = cast<CompositeType>(V->getType());
+ CompositeType *PTy = cast<CompositeType>(V->getType());
if (isa<UndefValue>(V))
return UndefValue::get(ExtractValueInst::getIndexedType(PTy,
- idx_begin,
- idx_end));
+ idx_range));
else if (isa<ConstantAggregateZero>(V))
return Constant::getNullValue(ExtractValueInst::getIndexedType(PTy,
- idx_begin,
- idx_end));
+ idx_range));
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_range[0]), idx_range.slice(1),
+ InsertBefore);
} else if (InsertValueInst *I = dyn_cast<InsertValueInst>(V)) {
// Loop the indices for the insertvalue instruction in parallel with the
// requested indices
- const unsigned *req_idx = idx_begin;
+ const unsigned *req_idx = idx_range.begin();
for (const unsigned *i = I->idx_begin(), *e = I->idx_end();
i != e; ++i, ++req_idx) {
- if (req_idx == idx_end) {
+ if (req_idx == idx_range.end()) {
if (InsertBefore)
// The requested index identifies a part of a nested aggregate. Handle
// this specially. For example,
// %C = insertvalue {i32, i32 } %A, i32 11, 1
// which allows the unused 0,0 element from the nested struct to be
// removed.
- return BuildSubAggregate(V, idx_begin, req_idx, InsertBefore);
+ return BuildSubAggregate(V, makeArrayRef(idx_range.begin(), req_idx),
+ InsertBefore);
else
// We can't handle this without inserting insertvalues
return 0;
// See if the (aggregrate) value inserted into has the value we are
// looking for, then.
if (*req_idx != *i)
- return FindInsertedValue(I->getAggregateOperand(), idx_begin, idx_end,
+ return FindInsertedValue(I->getAggregateOperand(), idx_range,
InsertBefore);
}
// If we end up here, the indices of the insertvalue match with those
// requested (though possibly only partially). Now we recursively look at
// the inserted value, passing any remaining indices.
- return FindInsertedValue(I->getInsertedValueOperand(), req_idx, idx_end,
+ return FindInsertedValue(I->getInsertedValueOperand(),
+ makeArrayRef(req_idx, idx_range.end()),
InsertBefore);
} else if (ExtractValueInst *I = dyn_cast<ExtractValueInst>(V)) {
// If we're extracting a value from an aggregrate that was extracted from
// However, we will need to chain I's indices with the requested indices.
// Calculate the number of indices required
- unsigned size = I->getNumIndices() + (idx_end - idx_begin);
+ unsigned size = I->getNumIndices() + idx_range.size();
// Allocate some space to put the new indices in
SmallVector<unsigned, 5> Idxs;
Idxs.reserve(size);
// Add indices from the extract value instruction
- for (const unsigned *i = I->idx_begin(), *e = I->idx_end();
- i != e; ++i)
- Idxs.push_back(*i);
+ Idxs.append(I->idx_begin(), I->idx_end());
// Add requested indices
- for (const unsigned *i = idx_begin, *e = idx_end; i != e; ++i)
- Idxs.push_back(*i);
+ Idxs.append(idx_range.begin(), idx_range.end());
assert(Idxs.size() == size
&& "Number of indices added not correct?");
- return FindInsertedValue(I->getAggregateOperand(), Idxs.begin(), Idxs.end(),
- InsertBefore);
+ return FindInsertedValue(I->getAggregateOperand(), Idxs, InsertBefore);
}
// Otherwise, we don't know (such as, extracting from a function return value
// or load instruction)
return 0;
}
+/// GetPointerBaseWithConstantOffset - Analyze the specified pointer to see if
+/// it can be expressed as a base pointer plus a constant offset. Return the
+/// base and offset to the caller.
+Value *llvm::GetPointerBaseWithConstantOffset(Value *Ptr, int64_t &Offset,
+ const TargetData &TD) {
+ Operator *PtrOp = dyn_cast<Operator>(Ptr);
+ if (PtrOp == 0) return Ptr;
+
+ // Just look through bitcasts.
+ if (PtrOp->getOpcode() == Instruction::BitCast)
+ return GetPointerBaseWithConstantOffset(PtrOp->getOperand(0), Offset, TD);
+
+ // If this is a GEP with constant indices, we can look through it.
+ GEPOperator *GEP = dyn_cast<GEPOperator>(PtrOp);
+ if (GEP == 0 || !GEP->hasAllConstantIndices()) return Ptr;
+
+ gep_type_iterator GTI = gep_type_begin(GEP);
+ for (User::op_iterator I = GEP->idx_begin(), E = GEP->idx_end(); I != E;
+ ++I, ++GTI) {
+ ConstantInt *OpC = cast<ConstantInt>(*I);
+ if (OpC->isZero()) continue;
+
+ // Handle a struct and array indices which add their offset to the pointer.
+ if (StructType *STy = dyn_cast<StructType>(*GTI)) {
+ Offset += TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
+ } else {
+ uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType());
+ Offset += OpC->getSExtValue()*Size;
+ }
+ }
+
+ // Re-sign extend from the pointer size if needed to get overflow edge cases
+ // right.
+ unsigned PtrSize = TD.getPointerSizeInBits();
+ if (PtrSize < 64)
+ Offset = (Offset << (64-PtrSize)) >> (64-PtrSize);
+
+ return GetPointerBaseWithConstantOffset(GEP->getPointerOperand(), Offset, TD);
+}
+
+
/// 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 StopAtNul) {
+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)) {
+ // any other way.
+ 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)
return false;
// 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::getInt8Ty(V->getContext()))
+ PointerType *PT = cast<PointerType>(GEP->getOperand(0)->getType());
+ ArrayType *AT = dyn_cast<ArrayType>(PT->getElementType());
+ 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;
return GetConstantStringInfo(GEP->getOperand(0), Str, StartIdx+Offset,
StopAtNul);
}
-
- if (MDString *MDStr = dyn_cast<MDString>(V)) {
- Str = MDStr->getString();
- return true;
- }
// 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);
+ 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)) {
+ // Handle the all-zeros case
+ if (GlobalInit->isNullValue()) {
// This is a degenerate case. The initializer is constant zero so the
// length of the string must be zero.
Str.clear();
}
// Must be a Constant Array
- ConstantArray *Array = dyn_cast<ConstantArray>(GlobalInit);
- if (Array == 0 ||
- Array->getType()->getElementType() != Type::getInt8Ty(V->getContext()))
+ 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;
+ }
+
+ // As a special-case, "@string = constant i8 0" is also a string with zero
+ // length, not wrapped in a bitcast or GEP.
+ if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) {
+ if (GV->isConstant() && GV->hasDefinitiveInitializer())
+ if (GV->getInitializer()->isNullValue()) return 1;
+ return 0;
+ }
+
+ // 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;
+}
+
+Value *
+llvm::GetUnderlyingObject(Value *V, const TargetData *TD, unsigned MaxLookup) {
+ if (!V->getType()->isPointerTy())
+ return V;
+ for (unsigned Count = 0; MaxLookup == 0 || Count < MaxLookup; ++Count) {
+ if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
+ V = GEP->getPointerOperand();
+ } else if (Operator::getOpcode(V) == Instruction::BitCast) {
+ V = cast<Operator>(V)->getOperand(0);
+ } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
+ if (GA->mayBeOverridden())
+ return V;
+ V = GA->getAliasee();
+ } else {
+ // See if InstructionSimplify knows any relevant tricks.
+ if (Instruction *I = dyn_cast<Instruction>(V))
+ // TODO: Acquire a DominatorTree and use it.
+ if (Value *Simplified = SimplifyInstruction(I, TD, 0)) {
+ V = Simplified;
+ continue;
+ }
+
+ return V;
+ }
+ assert(V->getType()->isPointerTy() && "Unexpected operand type!");
+ }
+ return V;
+}
+
+/// onlyUsedByLifetimeMarkers - Return true if the only users of this pointer
+/// are lifetime markers.
+///
+bool llvm::onlyUsedByLifetimeMarkers(const Value *V) {
+ for (Value::const_use_iterator UI = V->use_begin(), UE = V->use_end();
+ UI != UE; ++UI) {
+ const IntrinsicInst *II = dyn_cast<IntrinsicInst>(*UI);
+ if (!II) return false;
+
+ if (II->getIntrinsicID() != Intrinsic::lifetime_start &&
+ II->getIntrinsicID() != Intrinsic::lifetime_end)
+ return false;
+ }
+ return true;
+}
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