diff --git a/include/llvm/Analysis/ValueTracking.h b/include/llvm/Analysis/ValueTracking.h index 121da79cb96..05968914b94 100644 --- a/include/llvm/Analysis/ValueTracking.h +++ b/include/llvm/Analysis/ValueTracking.h @@ -19,6 +19,7 @@ #include namespace llvm { + template class SmallVectorImpl; class Value; class Instruction; class APInt; @@ -77,6 +78,20 @@ namespace llvm { /// bool CannotBeNegativeZero(const Value *V, unsigned Depth = 0); + /// 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. + /// + /// 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 *DecomposeGEPExpression(const Value *V, int64_t &BaseOffs, + SmallVectorImpl > &VarIndices, + const TargetData *TD); + + + /// FindScalarValue - Given an aggregrate and an sequence of indices, see if /// the scalar value indexed is already around as a register, for example if /// it were inserted directly into the aggregrate. diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp index e10e1f2d4ce..b2983c722e2 100644 --- a/lib/Analysis/BasicAliasAnalysis.cpp +++ b/lib/Analysis/BasicAliasAnalysis.cpp @@ -18,7 +18,6 @@ #include "llvm/Constants.h" #include "llvm/DerivedTypes.h" #include "llvm/Function.h" -#include "llvm/GlobalAlias.h" #include "llvm/GlobalVariable.h" #include "llvm/Instructions.h" #include "llvm/IntrinsicInst.h" @@ -28,11 +27,9 @@ #include "llvm/Analysis/MemoryBuiltins.h" #include "llvm/Analysis/ValueTracking.h" #include "llvm/Target/TargetData.h" -#include "llvm/ADT/SmallSet.h" +#include "llvm/ADT/SmallPtrSet.h" #include "llvm/ADT/SmallVector.h" -#include "llvm/ADT/STLExtras.h" #include "llvm/Support/ErrorHandling.h" -#include "llvm/Support/GetElementPtrTypeIterator.h" #include using namespace llvm; @@ -379,160 +376,6 @@ BasicAliasAnalysis::getModRefInfo(CallSite CS1, CallSite CS2) { return NoAA::getModRefInfo(CS1, CS2); } -/// GetLinearExpression - Analyze the specified value as a linear expression: -/// "A*V + B". Return the scale and offset values as APInts and return V as a -/// Value*. The incoming Value is known to be a scalar integer. -static Value *GetLinearExpression(Value *V, APInt &Scale, APInt &Offset, - const TargetData *TD) { - assert(isa(V->getType()) && "Not an integer value"); - - if (BinaryOperator *BOp = dyn_cast(V)) { - if (ConstantInt *RHSC = dyn_cast(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; - } - } - } - - 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. -/// -/// 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. -/// -/// FIXME: Move this out to ValueTracking.cpp -/// -static const Value *DecomposeGEPExpression(const Value *V, int64_t &BaseOffs, - SmallVectorImpl > &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(V); - if (Op == 0) { - // The only non-operator case we can handle are GlobalAliases. - if (const GlobalAlias *GA = dyn_cast(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(Op); - if (GEPOp == 0) - return V; - - // Don't attempt to analyze GEPs over unsized objects. - if (!cast(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 = next(GEPOp->op_begin()), - 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(*GTI++)) { - // For a struct, add the member offset. - unsigned FieldNo = cast(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(Index)) { - if (CIdx->isZero()) continue; - BaseOffs += TD->getTypeAllocSize(*GTI)*CIdx->getSExtValue(); - continue; - } - - // TODO: Could handle linear expressions here like A[X+1], also A[X*4|1]. - uint64_t Scale = TD->getTypeAllocSize(*GTI); - - unsigned Width = cast(Index->getType())->getBitWidth(); - APInt IndexScale(Width, 0), IndexOffset(Width, 0); - Index = GetLinearExpression(Index, IndexScale, IndexOffset, TD); - - Scale *= IndexScale.getZExtValue(); - BaseOffs += IndexOffset.getZExtValue()*Scale; - - - // 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); - } -} - /// GetIndiceDifference - Dest and Src are the variable indices from two /// decomposed GetElementPtr instructions GEP1 and GEP2 which have common base /// pointers. Subtract the GEP2 indices from GEP1 to find the symbolic diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp index f4b550f9f73..5f9d0370f50 100644 --- a/lib/Analysis/ValueTracking.cpp +++ b/lib/Analysis/ValueTracking.cpp @@ -948,6 +948,160 @@ bool llvm::CannotBeNegativeZero(const Value *V, unsigned Depth) { return false; } + +/// GetLinearExpression - Analyze the specified value as a linear expression: +/// "A*V + B". Return the scale and offset values as APInts and return V as a +/// Value*. The incoming Value is known to be a scalar integer. +static Value *GetLinearExpression(Value *V, APInt &Scale, APInt &Offset, + const TargetData *TD) { + assert(isa(V->getType()) && "Not an integer value"); + + if (BinaryOperator *BOp = dyn_cast(V)) { + if (ConstantInt *RHSC = dyn_cast(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; + } + } + } + + 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. +/// +/// 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 > &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(V); + if (Op == 0) { + // The only non-operator case we can handle are GlobalAliases. + if (const GlobalAlias *GA = dyn_cast(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(Op); + if (GEPOp == 0) + return V; + + // Don't attempt to analyze GEPs over unsized objects. + if (!cast(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(*GTI++)) { + // For a struct, add the member offset. + unsigned FieldNo = cast(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(Index)) { + if (CIdx->isZero()) continue; + BaseOffs += TD->getTypeAllocSize(*GTI)*CIdx->getSExtValue(); + continue; + } + + // TODO: Could handle linear expressions here like A[X+1], also A[X*4|1]. + uint64_t Scale = TD->getTypeAllocSize(*GTI); + + unsigned Width = cast(Index->getType())->getBitWidth(); + APInt IndexScale(Width, 0), IndexOffset(Width, 0); + Index = GetLinearExpression(Index, IndexScale, IndexOffset, TD); + + Scale *= IndexScale.getZExtValue(); + BaseOffs += IndexOffset.getZExtValue()*Scale; + + + // 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); + } +} + + // 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