#include "llvm/Instructions.h"
#include "llvm/GlobalVariable.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 <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
void llvm::ComputeMaskedBits(Value *V, const APInt &Mask,
APInt &KnownZero, APInt &KnownOne,
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()->isInt
eger() || isa<PointerType>(V->getType())) &&
+ assert((V->getType()->isInt
OrIntVector() || 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((!TD ||
+ TD->getTypeSizeInBits(V->getType()->getScalarType()) == BitWidth) &&
+ (!V->getType()->isIntOrIntVector() ||
+ 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));
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.
const Type *SrcTy = I->getOperand(0)->getType();
unsigned SrcBitWidth = TD ?
TD->getTypeSizeInBits(SrcTy) :
- SrcTy->getPrimitiveSizeInBits();
+ 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->isInteger() || isa<PointerType>(SrcTy)) &&
+ // TODO: For now, not handling conversions like:
+ // (bitcast i64 %x to <2 x i32>)
+ !isa<VectorType>(I->getType())) {
ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, TD,
Depth+1);
return;
}
// 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, than 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:
// 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:
/// '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();
+ assert((TD || V->getType()->isIntOrIntVector()) &&
+ "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();
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);
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 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;
- break;
- case 4: // abs[lf](x) != -0.0
- if (!strcmp(F->getNameStart(), "absf")) return true;
- if (!strcmp(F->getNameStart(), "absl")) return true;
- break;
- }
+ // abs(x) != -0.0
+ if (F->getName() == "abs") return true;
+ // abs[lf](x) != -0.0
+ if (F->getName() == "absf") return true;
+ if (F->getName() == "absl") return true;
}
}
// 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,
+ LLVMContext &Context,
+ Instruction *InsertBefore) {
const llvm::StructType *STy = llvm::dyn_cast<llvm::StructType>(IndexedType);
if (STy) {
// Save the original To argument so we can modify it
Idxs.push_back(i);
Value *PrevTo = To;
To = BuildSubAggregate(From, To, STy->getElementType(i), Idxs, IdxSkip,
- InsertBefore);
+ Context, InsertBefore);
Idxs.pop_back();
if (!To) {
// Couldn't find any inserted value for this index? Cleanup
// 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.begin(), Idxs.end(), Context);
if (!V)
return NULL;
// 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, LLVMContext &Context,
+ Instruction *InsertBefore) {
assert(InsertBefore && "Must have someplace to insert!");
const Type *IndexedType = ExtractValueInst::getIndexedType(From->getType(),
idx_begin,
SmallVector<unsigned, 10> Idxs(idx_begin, idx_end);
unsigned IdxSkip = Idxs.size();
- return BuildSubAggregate(From, To, IndexedType, Idxs, IdxSkip, InsertBefore);
+ return BuildSubAggregate(From, To, IndexedType, Idxs, IdxSkip,
+ Context, InsertBefore);
}
/// FindInsertedValue - Given an aggregrate and an sequence of indices, see if
/// 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) {
+ const unsigned *idx_end, LLVMContext &Context,
+ Instruction *InsertBefore) {
// Nothing to index? Just return V then (this is useful at the end of our
// recursion)
if (idx_begin == idx_end)
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, Context, InsertBefore);
} else if (InsertValueInst *I = dyn_cast<InsertValueInst>(V)) {
// Loop the indices for the insertvalue instruction in parallel with the
// requested indices
// %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, idx_begin, req_idx,
+ Context, InsertBefore);
else
// We can't handle this without inserting insertvalues
return 0;
// looking for, then.
if (*req_idx != *i)
return FindInsertedValue(I->getAggregateOperand(), idx_begin, idx_end,
- InsertBefore);
+ Context, 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,
- InsertBefore);
+ Context, InsertBefore);
} else if (ExtractValueInst *I = dyn_cast<ExtractValueInst>(V)) {
// If we're extracting a value from an aggregrate that was extracted from
// something else, we can extract from that something else directly instead.
&& "Number of indices added not correct?");
return FindInsertedValue(I->getAggregateOperand(), Idxs.begin(), Idxs.end(),
- InsertBefore);
+ Context, InsertBefore);
}
// Otherwise, we don't know (such as, extracting from a function return value
// or load instruction)
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