X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FVMCore%2FConstantFold.cpp;h=e42de2a7e3951aaca833322b83cb7ed7c6169b0e;hb=dd68469382cafff2051289707ea2d3e0d26919b1;hp=32b9ebba742d550404467f542fe3169df82091e0;hpb=b576c94c15af9a440f69d9d03c2afead7971118c;p=oota-llvm.git diff --git a/lib/VMCore/ConstantFold.cpp b/lib/VMCore/ConstantFold.cpp index 32b9ebba742..e42de2a7e39 100644 --- a/lib/VMCore/ConstantFold.cpp +++ b/lib/VMCore/ConstantFold.cpp @@ -1,4 +1,4 @@ -//===- ConstantHandling.cpp - Implement ConstantHandling.h ----------------===// +//===- ConstantFolding.cpp - LLVM constant folder -------------------------===// // // The LLVM Compiler Infrastructure // @@ -7,197 +7,67 @@ // //===----------------------------------------------------------------------===// // -// This file implements the various intrinsic operations, on constant values. +// This file implements folding of constants for LLVM. This implements the +// (internal) ConstantFolding.h interface, which is used by the +// ConstantExpr::get* methods to automatically fold constants when possible. +// +// The current constant folding implementation is implemented in two pieces: the +// template-based folder for simple primitive constants like ConstantInt, and +// the special case hackery that we use to symbolically evaluate expressions +// that use ConstantExprs. // //===----------------------------------------------------------------------===// -#include "llvm/ConstantHandling.h" -#include "llvm/iPHINode.h" -#include "llvm/InstrTypes.h" +#include "ConstantFolding.h" +#include "llvm/Constants.h" +#include "llvm/Instructions.h" #include "llvm/DerivedTypes.h" +#include "llvm/Function.h" +#include "llvm/Support/GetElementPtrTypeIterator.h" #include +using namespace llvm; -AnnotationID ConstRules::AID(AnnotationManager::getID("opt::ConstRules", - &ConstRules::find)); - -// ConstantFoldInstruction - Attempt to constant fold the specified instruction. -// If successful, the constant result is returned, if not, null is returned. -// -Constant *ConstantFoldInstruction(Instruction *I) { - if (PHINode *PN = dyn_cast(I)) { - if (PN->getNumIncomingValues() == 0) - return Constant::getNullValue(PN->getType()); +namespace { + struct ConstRules { + ConstRules() {} - Constant *Result = dyn_cast(PN->getIncomingValue(0)); - if (Result == 0) return 0; - - // Handle PHI nodes specially here... - for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i) - if (PN->getIncomingValue(i) != Result) - return 0; // Not all the same incoming constants... - - // If we reach here, all incoming values are the same constant. - return Result; - } - - Constant *Op0 = 0; - Constant *Op1 = 0; - - if (I->getNumOperands() != 0) { // Get first operand if it's a constant... - Op0 = dyn_cast(I->getOperand(0)); - if (Op0 == 0) return 0; // Not a constant?, can't fold - - if (I->getNumOperands() != 1) { // Get second operand if it's a constant... - Op1 = dyn_cast(I->getOperand(1)); - if (Op1 == 0) return 0; // Not a constant?, can't fold - } - } - - if (isa(I)) - return ConstantExpr::get(I->getOpcode(), Op0, Op1); - - switch (I->getOpcode()) { - case Instruction::Cast: - return ConstantExpr::getCast(Op0, I->getType()); - case Instruction::Shl: - case Instruction::Shr: - return ConstantExpr::getShift(I->getOpcode(), Op0, Op1); - case Instruction::GetElementPtr: { - std::vector IdxList; - IdxList.reserve(I->getNumOperands()-1); - if (Op1) IdxList.push_back(Op1); - for (unsigned i = 2, e = I->getNumOperands(); i != e; ++i) - if (Constant *C = dyn_cast(I->getOperand(i))) - IdxList.push_back(C); - else - return 0; // Non-constant operand - return ConstantExpr::getGetElementPtr(Op0, IdxList); - } - default: - return 0; - } -} - -static unsigned getSize(const Type *Ty) { - unsigned S = Ty->getPrimitiveSize(); - return S ? S : 8; // Treat pointers at 8 bytes -} - -Constant *ConstantFoldCastInstruction(const Constant *V, const Type *DestTy) { - if (V->getType() == DestTy) return (Constant*)V; - - if (const ConstantExpr *CE = dyn_cast(V)) - if (CE->getOpcode() == Instruction::Cast) { - Constant *Op = const_cast(CE->getOperand(0)); - // Try to not produce a cast of a cast, which is almost always redundant. - if (!Op->getType()->isFloatingPoint() && - !CE->getType()->isFloatingPoint() && - !DestTy->getType()->isFloatingPoint()) { - unsigned S1 = getSize(Op->getType()), S2 = getSize(CE->getType()); - unsigned S3 = getSize(DestTy); - if (Op->getType() == DestTy && S3 >= S2) - return Op; - if (S1 >= S2 && S2 >= S3) - return ConstantExpr::getCast(Op, DestTy); - if (S1 <= S2 && S2 >= S3 && S1 <= S3) - return ConstantExpr::getCast(Op, DestTy); - } - } else if (CE->getOpcode() == Instruction::GetElementPtr) { - // If all of the indexes in the GEP are null values, there is no pointer - // adjustment going on. We might as well cast the source pointer. - bool isAllNull = true; - for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i) - if (!CE->getOperand(i)->isNullValue()) { - isAllNull = false; - break; - } - if (isAllNull) - return ConstantExpr::getCast(CE->getOperand(0), DestTy); - } - - return ConstRules::get(*V, *V)->castTo(V, DestTy); -} - -Constant *ConstantFoldBinaryInstruction(unsigned Opcode, const Constant *V1, - const Constant *V2) { - switch (Opcode) { - case Instruction::Add: return *V1 + *V2; - case Instruction::Sub: return *V1 - *V2; - case Instruction::Mul: return *V1 * *V2; - case Instruction::Div: return *V1 / *V2; - case Instruction::Rem: return *V1 % *V2; - case Instruction::And: return *V1 & *V2; - case Instruction::Or: return *V1 | *V2; - case Instruction::Xor: return *V1 ^ *V2; - - case Instruction::SetEQ: return *V1 == *V2; - case Instruction::SetNE: return *V1 != *V2; - case Instruction::SetLE: return *V1 <= *V2; - case Instruction::SetGE: return *V1 >= *V2; - case Instruction::SetLT: return *V1 < *V2; - case Instruction::SetGT: return *V1 > *V2; - } - return 0; -} - -Constant *ConstantFoldShiftInstruction(unsigned Opcode, const Constant *V1, - const Constant *V2) { - switch (Opcode) { - case Instruction::Shl: return *V1 << *V2; - case Instruction::Shr: return *V1 >> *V2; - default: return 0; - } -} - -Constant *ConstantFoldGetElementPtr(const Constant *C, - const std::vector &IdxList) { - if (IdxList.size() == 0 || - (IdxList.size() == 1 && IdxList[0]->isNullValue())) - return const_cast(C); - - // TODO If C is null and all idx's are null, return null of the right type. - - - if (const ConstantExpr *CE = dyn_cast(C)) { - // Combine Indices - If the source pointer to this getelementptr instruction - // is a getelementptr instruction, combine the indices of the two - // getelementptr instructions into a single instruction. - // - if (CE->getOpcode() == Instruction::GetElementPtr) { - if (CE->getOperand(CE->getNumOperands()-1)->getType() == Type::LongTy) { - std::vector NewIndices; - NewIndices.reserve(IdxList.size() + CE->getNumOperands()); - for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i) - NewIndices.push_back(cast(CE->getOperand(i))); - - // Add the last index of the source with the first index of the new GEP. - Constant *Combined = - ConstantExpr::get(Instruction::Add, IdxList[0], - CE->getOperand(CE->getNumOperands()-1)); - - NewIndices.push_back(Combined); - NewIndices.insert(NewIndices.end(), IdxList.begin()+1, IdxList.end()); - return ConstantExpr::getGetElementPtr(CE->getOperand(0), NewIndices); - } - } - - // Implement folding of: - // int* getelementptr ([2 x int]* cast ([3 x int]* %X to [2 x int]*), - // long 0, long 0) - // To: int* getelementptr ([3 x int]* %X, long 0, long 0) + // Binary Operators... + virtual Constant *add(const Constant *V1, const Constant *V2) const = 0; + virtual Constant *sub(const Constant *V1, const Constant *V2) const = 0; + virtual Constant *mul(const Constant *V1, const Constant *V2) const = 0; + virtual Constant *div(const Constant *V1, const Constant *V2) const = 0; + virtual Constant *rem(const Constant *V1, const Constant *V2) const = 0; + virtual Constant *op_and(const Constant *V1, const Constant *V2) const = 0; + virtual Constant *op_or (const Constant *V1, const Constant *V2) const = 0; + virtual Constant *op_xor(const Constant *V1, const Constant *V2) const = 0; + virtual Constant *shl(const Constant *V1, const Constant *V2) const = 0; + virtual Constant *shr(const Constant *V1, const Constant *V2) const = 0; + virtual Constant *lessthan(const Constant *V1, const Constant *V2) const =0; + virtual Constant *equalto(const Constant *V1, const Constant *V2) const = 0; + + // Casting operators. + virtual Constant *castToBool (const Constant *V) const = 0; + virtual Constant *castToSByte (const Constant *V) const = 0; + virtual Constant *castToUByte (const Constant *V) const = 0; + virtual Constant *castToShort (const Constant *V) const = 0; + virtual Constant *castToUShort(const Constant *V) const = 0; + virtual Constant *castToInt (const Constant *V) const = 0; + virtual Constant *castToUInt (const Constant *V) const = 0; + virtual Constant *castToLong (const Constant *V) const = 0; + virtual Constant *castToULong (const Constant *V) const = 0; + virtual Constant *castToFloat (const Constant *V) const = 0; + virtual Constant *castToDouble(const Constant *V) const = 0; + virtual Constant *castToPointer(const Constant *V, + const PointerType *Ty) const = 0; + + // ConstRules::get - Return an instance of ConstRules for the specified + // constant operands. // - if (CE->getOpcode() == Instruction::Cast && IdxList.size() > 1 && - IdxList[0]->isNullValue()) - if (const PointerType *SPT = - dyn_cast(CE->getOperand(0)->getType())) - if (const ArrayType *SAT = dyn_cast(SPT->getElementType())) - if (const ArrayType *CAT = - dyn_cast(cast(C->getType())->getElementType())) - if (CAT->getElementType() == SAT->getElementType()) - return ConstantExpr::getGetElementPtr( - (Constant*)CE->getOperand(0), IdxList); - } - return 0; + static ConstRules &get(const Constant *V1, const Constant *V2); + private: + ConstRules(const ConstRules &); // Do not implement + ConstRules &operator=(const ConstRules &); // Do not implement + }; } @@ -251,43 +121,45 @@ class TemplateRules : public ConstRules { return SubClassName::Shr((const ArgType *)V1, (const ArgType *)V2); } - virtual ConstantBool *lessthan(const Constant *V1, - const Constant *V2) const { + virtual Constant *lessthan(const Constant *V1, const Constant *V2) const { return SubClassName::LessThan((const ArgType *)V1, (const ArgType *)V2); } + virtual Constant *equalto(const Constant *V1, const Constant *V2) const { + return SubClassName::EqualTo((const ArgType *)V1, (const ArgType *)V2); + } // Casting operators. ick - virtual ConstantBool *castToBool(const Constant *V) const { + virtual Constant *castToBool(const Constant *V) const { return SubClassName::CastToBool((const ArgType*)V); } - virtual ConstantSInt *castToSByte(const Constant *V) const { + virtual Constant *castToSByte(const Constant *V) const { return SubClassName::CastToSByte((const ArgType*)V); } - virtual ConstantUInt *castToUByte(const Constant *V) const { + virtual Constant *castToUByte(const Constant *V) const { return SubClassName::CastToUByte((const ArgType*)V); } - virtual ConstantSInt *castToShort(const Constant *V) const { + virtual Constant *castToShort(const Constant *V) const { return SubClassName::CastToShort((const ArgType*)V); } - virtual ConstantUInt *castToUShort(const Constant *V) const { + virtual Constant *castToUShort(const Constant *V) const { return SubClassName::CastToUShort((const ArgType*)V); } - virtual ConstantSInt *castToInt(const Constant *V) const { + virtual Constant *castToInt(const Constant *V) const { return SubClassName::CastToInt((const ArgType*)V); } - virtual ConstantUInt *castToUInt(const Constant *V) const { + virtual Constant *castToUInt(const Constant *V) const { return SubClassName::CastToUInt((const ArgType*)V); } - virtual ConstantSInt *castToLong(const Constant *V) const { + virtual Constant *castToLong(const Constant *V) const { return SubClassName::CastToLong((const ArgType*)V); } - virtual ConstantUInt *castToULong(const Constant *V) const { + virtual Constant *castToULong(const Constant *V) const { return SubClassName::CastToULong((const ArgType*)V); } - virtual ConstantFP *castToFloat(const Constant *V) const { + virtual Constant *castToFloat(const Constant *V) const { return SubClassName::CastToFloat((const ArgType*)V); } - virtual ConstantFP *castToDouble(const Constant *V) const { + virtual Constant *castToDouble(const Constant *V) const { return SubClassName::CastToDouble((const ArgType*)V); } virtual Constant *castToPointer(const Constant *V, @@ -309,24 +181,27 @@ class TemplateRules : public ConstRules { static Constant *Xor(const ArgType *V1, const ArgType *V2) { return 0; } static Constant *Shl(const ArgType *V1, const ArgType *V2) { return 0; } static Constant *Shr(const ArgType *V1, const ArgType *V2) { return 0; } - static ConstantBool *LessThan(const ArgType *V1, const ArgType *V2) { + static Constant *LessThan(const ArgType *V1, const ArgType *V2) { + return 0; + } + static Constant *EqualTo(const ArgType *V1, const ArgType *V2) { return 0; } // Casting operators. ick - static ConstantBool *CastToBool (const Constant *V) { return 0; } - static ConstantSInt *CastToSByte (const Constant *V) { return 0; } - static ConstantUInt *CastToUByte (const Constant *V) { return 0; } - static ConstantSInt *CastToShort (const Constant *V) { return 0; } - static ConstantUInt *CastToUShort(const Constant *V) { return 0; } - static ConstantSInt *CastToInt (const Constant *V) { return 0; } - static ConstantUInt *CastToUInt (const Constant *V) { return 0; } - static ConstantSInt *CastToLong (const Constant *V) { return 0; } - static ConstantUInt *CastToULong (const Constant *V) { return 0; } - static ConstantFP *CastToFloat (const Constant *V) { return 0; } - static ConstantFP *CastToDouble(const Constant *V) { return 0; } - static Constant *CastToPointer(const Constant *, - const PointerType *) {return 0;} + static Constant *CastToBool (const Constant *V) { return 0; } + static Constant *CastToSByte (const Constant *V) { return 0; } + static Constant *CastToUByte (const Constant *V) { return 0; } + static Constant *CastToShort (const Constant *V) { return 0; } + static Constant *CastToUShort(const Constant *V) { return 0; } + static Constant *CastToInt (const Constant *V) { return 0; } + static Constant *CastToUInt (const Constant *V) { return 0; } + static Constant *CastToLong (const Constant *V) { return 0; } + static Constant *CastToULong (const Constant *V) { return 0; } + static Constant *CastToFloat (const Constant *V) { return 0; } + static Constant *CastToDouble(const Constant *V) { return 0; } + static Constant *CastToPointer(const Constant *, + const PointerType *) {return 0;} }; @@ -338,6 +213,10 @@ class TemplateRules : public ConstRules { // EmptyRules provides a concrete base class of ConstRules that does nothing // struct EmptyRules : public TemplateRules { + static Constant *EqualTo(const Constant *V1, const Constant *V2) { + if (V1 == V2) return ConstantBool::True; + return 0; + } }; @@ -350,10 +229,14 @@ struct EmptyRules : public TemplateRules { // struct BoolRules : public TemplateRules { - static ConstantBool *LessThan(const ConstantBool *V1, const ConstantBool *V2){ + static Constant *LessThan(const ConstantBool *V1, const ConstantBool *V2){ return ConstantBool::get(V1->getValue() < V2->getValue()); } + static Constant *EqualTo(const Constant *V1, const Constant *V2) { + return ConstantBool::get(V1 == V2); + } + static Constant *And(const ConstantBool *V1, const ConstantBool *V2) { return ConstantBool::get(V1->getValue() & V2->getValue()); } @@ -368,7 +251,7 @@ struct BoolRules : public TemplateRules { // Casting operators. ick #define DEF_CAST(TYPE, CLASS, CTYPE) \ - static CLASS *CastTo##TYPE (const ConstantBool *V) { \ + static Constant *CastTo##TYPE (const ConstantBool *V) { \ return CLASS::get(Type::TYPE##Ty, (CTYPE)(bool)V->getValue()); \ } @@ -388,64 +271,54 @@ struct BoolRules : public TemplateRules { //===----------------------------------------------------------------------===// -// PointerRules Class +// NullPointerRules Class //===----------------------------------------------------------------------===// // -// PointerRules provides a concrete base class of ConstRules for pointer types +// NullPointerRules provides a concrete base class of ConstRules for null +// pointers. // -struct PointerRules : public TemplateRules { - static ConstantBool *CastToBool (const Constant *V) { - if (V->isNullValue()) return ConstantBool::False; - return 0; // Can't const prop other types of pointers +struct NullPointerRules : public TemplateRules { + static Constant *EqualTo(const Constant *V1, const Constant *V2) { + return ConstantBool::True; // Null pointers are always equal } - static ConstantSInt *CastToSByte (const Constant *V) { - if (V->isNullValue()) return ConstantSInt::get(Type::SByteTy, 0); - return 0; // Can't const prop other types of pointers + static Constant *CastToBool(const Constant *V) { + return ConstantBool::False; } - static ConstantUInt *CastToUByte (const Constant *V) { - if (V->isNullValue()) return ConstantUInt::get(Type::UByteTy, 0); - return 0; // Can't const prop other types of pointers + static Constant *CastToSByte (const Constant *V) { + return ConstantSInt::get(Type::SByteTy, 0); } - static ConstantSInt *CastToShort (const Constant *V) { - if (V->isNullValue()) return ConstantSInt::get(Type::ShortTy, 0); - return 0; // Can't const prop other types of pointers + static Constant *CastToUByte (const Constant *V) { + return ConstantUInt::get(Type::UByteTy, 0); } - static ConstantUInt *CastToUShort(const Constant *V) { - if (V->isNullValue()) return ConstantUInt::get(Type::UShortTy, 0); - return 0; // Can't const prop other types of pointers + static Constant *CastToShort (const Constant *V) { + return ConstantSInt::get(Type::ShortTy, 0); } - static ConstantSInt *CastToInt (const Constant *V) { - if (V->isNullValue()) return ConstantSInt::get(Type::IntTy, 0); - return 0; // Can't const prop other types of pointers + static Constant *CastToUShort(const Constant *V) { + return ConstantUInt::get(Type::UShortTy, 0); } - static ConstantUInt *CastToUInt (const Constant *V) { - if (V->isNullValue()) return ConstantUInt::get(Type::UIntTy, 0); - return 0; // Can't const prop other types of pointers + static Constant *CastToInt (const Constant *V) { + return ConstantSInt::get(Type::IntTy, 0); } - static ConstantSInt *CastToLong (const Constant *V) { - if (V->isNullValue()) return ConstantSInt::get(Type::LongTy, 0); - return 0; // Can't const prop other types of pointers + static Constant *CastToUInt (const Constant *V) { + return ConstantUInt::get(Type::UIntTy, 0); } - static ConstantUInt *CastToULong (const Constant *V) { - if (V->isNullValue()) return ConstantUInt::get(Type::ULongTy, 0); - return 0; // Can't const prop other types of pointers + static Constant *CastToLong (const Constant *V) { + return ConstantSInt::get(Type::LongTy, 0); } - static ConstantFP *CastToFloat (const Constant *V) { - if (V->isNullValue()) return ConstantFP::get(Type::FloatTy, 0); - return 0; // Can't const prop other types of pointers + static Constant *CastToULong (const Constant *V) { + return ConstantUInt::get(Type::ULongTy, 0); } - static ConstantFP *CastToDouble(const Constant *V) { - if (V->isNullValue()) return ConstantFP::get(Type::DoubleTy, 0); - return 0; // Can't const prop other types of pointers + static Constant *CastToFloat (const Constant *V) { + return ConstantFP::get(Type::FloatTy, 0); + } + static Constant *CastToDouble(const Constant *V) { + return ConstantFP::get(Type::DoubleTy, 0); } - static Constant *CastToPointer(const ConstantPointer *V, + static Constant *CastToPointer(const ConstantPointerNull *V, const PointerType *PTy) { - if (V->getType() == PTy) - return const_cast(V); // Allow cast %PTy %ptr to %PTy - if (V->isNullValue()) - return ConstantPointerNull::get(PTy); - return 0; // Can't const prop other types of pointers + return ConstantPointerNull::get(PTy); } }; @@ -481,12 +354,16 @@ struct DirectRules : public TemplateRules { return ConstantClass::get(*Ty, R); } - static ConstantBool *LessThan(const ConstantClass *V1, - const ConstantClass *V2) { + static Constant *LessThan(const ConstantClass *V1, const ConstantClass *V2) { bool R = (BuiltinType)V1->getValue() < (BuiltinType)V2->getValue(); return ConstantBool::get(R); } + static Constant *EqualTo(const ConstantClass *V1, const ConstantClass *V2) { + bool R = (BuiltinType)V1->getValue() == (BuiltinType)V2->getValue(); + return ConstantBool::get(R); + } + static Constant *CastToPointer(const ConstantClass *V, const PointerType *PTy) { if (V->isNullValue()) // Is it a FP or Integral null value? @@ -496,7 +373,7 @@ struct DirectRules : public TemplateRules { // Casting operators. ick #define DEF_CAST(TYPE, CLASS, CTYPE) \ - static CLASS *CastTo##TYPE (const ConstantClass *V) { \ + static Constant *CastTo##TYPE (const ConstantClass *V) { \ return CLASS::get(Type::TYPE##Ty, (CTYPE)(BuiltinType)V->getValue()); \ } @@ -575,9 +452,9 @@ struct DirectIntRules // DirectFPRules Class //===----------------------------------------------------------------------===// // -// DirectFPRules provides implementations of functions that are valid on -// floating point types, but not all types in general. -// +/// DirectFPRules provides implementations of functions that are valid on +/// floating point types, but not all types in general. +/// template struct DirectFPRules : public DirectRules SByteR; + static DirectIntRules UByteR; + static DirectIntRules ShortR; + static DirectIntRules UShortR; + static DirectIntRules IntR; + static DirectIntRules UIntR; + static DirectIntRules LongR; + static DirectIntRules ULongR; + static DirectFPRules FloatR; + static DirectFPRules DoubleR; + + if (isa(V1) || isa(V2) || + isa(V1) || isa(V2)) + return EmptyR; + + switch (V1->getType()->getTypeID()) { + default: assert(0 && "Unknown value type for constant folding!"); + case Type::BoolTyID: return BoolR; + case Type::PointerTyID: return NullPointerR; + case Type::SByteTyID: return SByteR; + case Type::UByteTyID: return UByteR; + case Type::ShortTyID: return ShortR; + case Type::UShortTyID: return UShortR; + case Type::IntTyID: return IntR; + case Type::UIntTyID: return UIntR; + case Type::LongTyID: return LongR; + case Type::ULongTyID: return ULongR; + case Type::FloatTyID: return FloatR; + case Type::DoubleTyID: return DoubleR; + } +} + + //===----------------------------------------------------------------------===// -// DirectRules Subclasses +// ConstantFold*Instruction Implementations //===----------------------------------------------------------------------===// // -// Given the DirectRules class we can now implement lots of types with little -// code. Thank goodness C++ compilers are great at stomping out layers of -// templates... can you imagine having to do this all by hand? (/me is lazy :) +// These methods contain the special case hackery required to symbolically +// evaluate some constant expression cases, and use the ConstantRules class to +// evaluate normal constants. // +static unsigned getSize(const Type *Ty) { + unsigned S = Ty->getPrimitiveSize(); + return S ? S : 8; // Treat pointers at 8 bytes +} -// ConstRules::find - Return the constant rules that take care of the specified -// type. -// -Annotation *ConstRules::find(AnnotationID AID, const Annotable *TyA, void *) { - assert(AID == ConstRules::AID && "Bad annotation for factory!"); - const Type *Ty = cast((const Value*)TyA); +Constant *llvm::ConstantFoldCastInstruction(const Constant *V, + const Type *DestTy) { + if (V->getType() == DestTy) return (Constant*)V; + + // Cast of a global address to boolean is always true. + if (const ConstantPointerRef *CPR = dyn_cast(V)) + if (DestTy == Type::BoolTy) + // FIXME: When we support 'external weak' references, we have to prevent + // this transformation from happening. In the meantime we avoid folding + // any cast of an external symbol. + if (!CPR->getValue()->isExternal()) + return ConstantBool::True; + + if (const ConstantExpr *CE = dyn_cast(V)) + if (CE->getOpcode() == Instruction::Cast) { + Constant *Op = const_cast(CE->getOperand(0)); + // Try to not produce a cast of a cast, which is almost always redundant. + if (!Op->getType()->isFloatingPoint() && + !CE->getType()->isFloatingPoint() && + !DestTy->isFloatingPoint()) { + unsigned S1 = getSize(Op->getType()), S2 = getSize(CE->getType()); + unsigned S3 = getSize(DestTy); + if (Op->getType() == DestTy && S3 >= S2) + return Op; + if (S1 >= S2 && S2 >= S3) + return ConstantExpr::getCast(Op, DestTy); + if (S1 <= S2 && S2 >= S3 && S1 <= S3) + return ConstantExpr::getCast(Op, DestTy); + } + } else if (CE->getOpcode() == Instruction::GetElementPtr) { + // If all of the indexes in the GEP are null values, there is no pointer + // adjustment going on. We might as well cast the source pointer. + bool isAllNull = true; + for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i) + if (!CE->getOperand(i)->isNullValue()) { + isAllNull = false; + break; + } + if (isAllNull) + return ConstantExpr::getCast(CE->getOperand(0), DestTy); + } + + ConstRules &Rules = ConstRules::get(V, V); + + switch (DestTy->getTypeID()) { + case Type::BoolTyID: return Rules.castToBool(V); + case Type::UByteTyID: return Rules.castToUByte(V); + case Type::SByteTyID: return Rules.castToSByte(V); + case Type::UShortTyID: return Rules.castToUShort(V); + case Type::ShortTyID: return Rules.castToShort(V); + case Type::UIntTyID: return Rules.castToUInt(V); + case Type::IntTyID: return Rules.castToInt(V); + case Type::ULongTyID: return Rules.castToULong(V); + case Type::LongTyID: return Rules.castToLong(V); + case Type::FloatTyID: return Rules.castToFloat(V); + case Type::DoubleTyID: return Rules.castToDouble(V); + case Type::PointerTyID: + return Rules.castToPointer(V, cast(DestTy)); + default: return 0; + } +} + +Constant *llvm::ConstantFoldSelectInstruction(const Constant *Cond, + const Constant *V1, + const Constant *V2) { + if (Cond == ConstantBool::True) + return const_cast(V1); + else if (Cond == ConstantBool::False) + return const_cast(V2); + return 0; +} + + +/// IdxCompare - Compare the two constants as though they were getelementptr +/// indices. This allows coersion of the types to be the same thing. +/// +/// If the two constants are the "same" (after coersion), return 0. If the +/// first is less than the second, return -1, if the second is less than the +/// first, return 1. If the constants are not integral, return -2. +/// +static int IdxCompare(Constant *C1, Constant *C2) { + if (C1 == C2) return 0; + + // Ok, we found a different index. Are either of the operands + // ConstantExprs? If so, we can't do anything with them. + if (!isa(C1) || !isa(C2)) + return -2; // don't know! - switch (Ty->getPrimitiveID()) { - case Type::BoolTyID: return new BoolRules(); - case Type::PointerTyID: return new PointerRules(); - case Type::SByteTyID: - return new DirectIntRules(); - case Type::UByteTyID: - return new DirectIntRules(); - case Type::ShortTyID: - return new DirectIntRules(); - case Type::UShortTyID: - return new DirectIntRules(); - case Type::IntTyID: - return new DirectIntRules(); - case Type::UIntTyID: - return new DirectIntRules(); - case Type::LongTyID: - return new DirectIntRules(); - case Type::ULongTyID: - return new DirectIntRules(); - case Type::FloatTyID: - return new DirectFPRules(); - case Type::DoubleTyID: - return new DirectFPRules(); - default: - return new EmptyRules(); + // Ok, we have two differing integer indices. Sign extend them to be the same + // type. Long is always big enough, so we use it. + C1 = ConstantExpr::getSignExtend(C1, Type::LongTy); + C2 = ConstantExpr::getSignExtend(C2, Type::LongTy); + if (C1 == C2) return 0; // Are they just differing types? + + // If they are really different, now that they are the same type, then we + // found a difference! + if (cast(C1)->getValue() < cast(C2)->getValue()) + return -1; + else + return 1; +} + +/// evaluateRelation - This function determines if there is anything we can +/// decide about the two constants provided. This doesn't need to handle simple +/// things like integer comparisons, but should instead handle ConstantExpr's +/// and ConstantPointerRef's. If we can determine that the two constants have a +/// particular relation to each other, we should return the corresponding SetCC +/// code, otherwise return Instruction::BinaryOpsEnd. +/// +/// To simplify this code we canonicalize the relation so that the first +/// operand is always the most "complex" of the two. We consider simple +/// constants (like ConstantInt) to be the simplest, followed by +/// ConstantPointerRef's, followed by ConstantExpr's (the most complex). +/// +static Instruction::BinaryOps evaluateRelation(const Constant *V1, + const Constant *V2) { + assert(V1->getType() == V2->getType() && + "Cannot compare different types of values!"); + if (V1 == V2) return Instruction::SetEQ; + + if (!isa(V1) && !isa(V1)) { + // If the first operand is simple, swap operands. + assert((isa(V2) || isa(V2)) && + "Simple cases should have been handled by caller!"); + Instruction::BinaryOps SwappedRelation = evaluateRelation(V2, V1); + if (SwappedRelation != Instruction::BinaryOpsEnd) + return SetCondInst::getSwappedCondition(SwappedRelation); + + } else if (const ConstantPointerRef *CPR1 = dyn_cast(V1)){ + if (isa(V2)) { // Swap as necessary. + Instruction::BinaryOps SwappedRelation = evaluateRelation(V2, V1); + if (SwappedRelation != Instruction::BinaryOpsEnd) + return SetCondInst::getSwappedCondition(SwappedRelation); + else + return Instruction::BinaryOpsEnd; + } + + // Now we know that the RHS is a ConstantPointerRef or simple constant, + // which (since the types must match) means that it's a ConstantPointerNull. + if (const ConstantPointerRef *CPR2 = dyn_cast(V2)) { + assert(CPR1->getValue() != CPR2->getValue() && + "CPRs for the same value exist at different addresses??"); + // FIXME: If both globals are external weak, they might both be null! + return Instruction::SetNE; + } else { + assert(isa(V2) && "Canonicalization guarantee!"); + // Global can never be null. FIXME: if we implement external weak + // linkage, this is not necessarily true! + return Instruction::SetNE; + } + + } else { + // Ok, the LHS is known to be a constantexpr. The RHS can be any of a + // constantexpr, a CPR, or a simple constant. + const ConstantExpr *CE1 = cast(V1); + Constant *CE1Op0 = CE1->getOperand(0); + + switch (CE1->getOpcode()) { + case Instruction::Cast: + // If the cast is not actually changing bits, and the second operand is a + // null pointer, do the comparison with the pre-casted value. + if (V2->isNullValue() && + CE1->getType()->isLosslesslyConvertibleTo(CE1Op0->getType())) + return evaluateRelation(CE1Op0, + Constant::getNullValue(CE1Op0->getType())); + break; + + case Instruction::GetElementPtr: + // Ok, since this is a getelementptr, we know that the constant has a + // pointer type. Check the various cases. + if (isa(V2)) { + // If we are comparing a GEP to a null pointer, check to see if the base + // of the GEP equals the null pointer. + if (isa(CE1Op0)) { + // FIXME: this is not true when we have external weak references! + // No offset can go from a global to a null pointer. + return Instruction::SetGT; + } else if (isa(CE1Op0)) { + // If we are indexing from a null pointer, check to see if we have any + // non-zero indices. + for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i) + if (!CE1->getOperand(i)->isNullValue()) + // Offsetting from null, must not be equal. + return Instruction::SetGT; + // Only zero indexes from null, must still be zero. + return Instruction::SetEQ; + } + // Otherwise, we can't really say if the first operand is null or not. + } else if (const ConstantPointerRef *CPR2 = + dyn_cast(V2)) { + if (isa(CE1Op0)) { + // FIXME: This is not true with external weak references. + return Instruction::SetLT; + } else if (const ConstantPointerRef *CPR1 = + dyn_cast(CE1Op0)) { + if (CPR1 == CPR2) { + // If this is a getelementptr of the same global, then it must be + // different. Because the types must match, the getelementptr could + // only have at most one index, and because we fold getelementptr's + // with a single zero index, it must be nonzero. + assert(CE1->getNumOperands() == 2 && + !CE1->getOperand(1)->isNullValue() && + "Suprising getelementptr!"); + return Instruction::SetGT; + } else { + // If they are different globals, we don't know what the value is, + // but they can't be equal. + return Instruction::SetNE; + } + } + } else { + const ConstantExpr *CE2 = cast(V2); + const Constant *CE2Op0 = CE2->getOperand(0); + + // There are MANY other foldings that we could perform here. They will + // probably be added on demand, as they seem needed. + switch (CE2->getOpcode()) { + default: break; + case Instruction::GetElementPtr: + // By far the most common case to handle is when the base pointers are + // obviously to the same or different globals. + if (isa(CE1Op0) && + isa(CE2Op0)) { + if (CE1Op0 != CE2Op0) // Don't know relative ordering, but not equal + return Instruction::SetNE; + // Ok, we know that both getelementptr instructions are based on the + // same global. From this, we can precisely determine the relative + // ordering of the resultant pointers. + unsigned i = 1; + + // Compare all of the operands the GEP's have in common. + for (;i != CE1->getNumOperands() && i != CE2->getNumOperands(); ++i) + switch (IdxCompare(CE1->getOperand(i), CE2->getOperand(i))) { + case -1: return Instruction::SetLT; + case 1: return Instruction::SetGT; + case -2: return Instruction::BinaryOpsEnd; + } + + // Ok, we ran out of things they have in common. If any leftovers + // are non-zero then we have a difference, otherwise we are equal. + for (; i < CE1->getNumOperands(); ++i) + if (!CE1->getOperand(i)->isNullValue()) + return Instruction::SetGT; + for (; i < CE2->getNumOperands(); ++i) + if (!CE2->getOperand(i)->isNullValue()) + return Instruction::SetLT; + return Instruction::SetEQ; + } + } + } + + default: + break; + } + } + + return Instruction::BinaryOpsEnd; +} + +Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode, + const Constant *V1, + const Constant *V2) { + Constant *C = 0; + switch (Opcode) { + default: break; + case Instruction::Add: C = ConstRules::get(V1, V2).add(V1, V2); break; + case Instruction::Sub: C = ConstRules::get(V1, V2).sub(V1, V2); break; + case Instruction::Mul: C = ConstRules::get(V1, V2).mul(V1, V2); break; + case Instruction::Div: C = ConstRules::get(V1, V2).div(V1, V2); break; + case Instruction::Rem: C = ConstRules::get(V1, V2).rem(V1, V2); break; + case Instruction::And: C = ConstRules::get(V1, V2).op_and(V1, V2); break; + case Instruction::Or: C = ConstRules::get(V1, V2).op_or (V1, V2); break; + case Instruction::Xor: C = ConstRules::get(V1, V2).op_xor(V1, V2); break; + case Instruction::Shl: C = ConstRules::get(V1, V2).shl(V1, V2); break; + case Instruction::Shr: C = ConstRules::get(V1, V2).shr(V1, V2); break; + case Instruction::SetEQ: C = ConstRules::get(V1, V2).equalto(V1, V2); break; + case Instruction::SetLT: C = ConstRules::get(V1, V2).lessthan(V1, V2);break; + case Instruction::SetGT: C = ConstRules::get(V1, V2).lessthan(V2, V1);break; + case Instruction::SetNE: // V1 != V2 === !(V1 == V2) + C = ConstRules::get(V1, V2).equalto(V1, V2); + if (C) return ConstantExpr::get(Instruction::Xor, C, ConstantBool::True); + break; + case Instruction::SetLE: // V1 <= V2 === !(V2 < V1) + C = ConstRules::get(V1, V2).lessthan(V2, V1); + if (C) return ConstantExpr::get(Instruction::Xor, C, ConstantBool::True); + break; + case Instruction::SetGE: // V1 >= V2 === !(V1 < V2) + C = ConstRules::get(V1, V2).lessthan(V1, V2); + if (C) return ConstantExpr::get(Instruction::Xor, C, ConstantBool::True); + break; + } + + // If we successfully folded the expression, return it now. + if (C) return C; + + if (SetCondInst::isRelational(Opcode)) + switch (evaluateRelation(V1, V2)) { + default: assert(0 && "Unknown relational!"); + case Instruction::BinaryOpsEnd: + break; // Couldn't determine anything about these constants. + case Instruction::SetEQ: // We know the constants are equal! + // If we know the constants are equal, we can decide the result of this + // computation precisely. + return ConstantBool::get(Opcode == Instruction::SetEQ || + Opcode == Instruction::SetLE || + Opcode == Instruction::SetGE); + case Instruction::SetLT: + // If we know that V1 < V2, we can decide the result of this computation + // precisely. + return ConstantBool::get(Opcode == Instruction::SetLT || + Opcode == Instruction::SetNE || + Opcode == Instruction::SetLE); + case Instruction::SetGT: + // If we know that V1 > V2, we can decide the result of this computation + // precisely. + return ConstantBool::get(Opcode == Instruction::SetGT || + Opcode == Instruction::SetNE || + Opcode == Instruction::SetGE); + case Instruction::SetLE: + // If we know that V1 <= V2, we can only partially decide this relation. + if (Opcode == Instruction::SetGT) return ConstantBool::False; + if (Opcode == Instruction::SetLT) return ConstantBool::True; + break; + + case Instruction::SetGE: + // If we know that V1 >= V2, we can only partially decide this relation. + if (Opcode == Instruction::SetLT) return ConstantBool::False; + if (Opcode == Instruction::SetGT) return ConstantBool::True; + break; + + case Instruction::SetNE: + // If we know that V1 != V2, we can only partially decide this relation. + if (Opcode == Instruction::SetEQ) return ConstantBool::False; + if (Opcode == Instruction::SetNE) return ConstantBool::True; + break; + } + + if (const ConstantExpr *CE1 = dyn_cast(V1)) { + if (const ConstantExpr *CE2 = dyn_cast(V2)) { + // There are many possible foldings we could do here. We should probably + // at least fold add of a pointer with an integer into the appropriate + // getelementptr. This will improve alias analysis a bit. + + + + + } else { + // Just implement a couple of simple identities. + switch (Opcode) { + case Instruction::Add: + if (V2->isNullValue()) return const_cast(V1); // X + 0 == X + break; + case Instruction::Sub: + if (V2->isNullValue()) return const_cast(V1); // X - 0 == X + break; + case Instruction::Mul: + if (V2->isNullValue()) return const_cast(V2); // X * 0 == 0 + if (const ConstantInt *CI = dyn_cast(V2)) + if (CI->getRawValue() == 1) + return const_cast(V1); // X * 1 == X + break; + case Instruction::Div: + if (const ConstantInt *CI = dyn_cast(V2)) + if (CI->getRawValue() == 1) + return const_cast(V1); // X / 1 == X + break; + case Instruction::Rem: + if (const ConstantInt *CI = dyn_cast(V2)) + if (CI->getRawValue() == 1) + return Constant::getNullValue(CI->getType()); // X % 1 == 0 + break; + case Instruction::And: + if (cast(V2)->isAllOnesValue()) + return const_cast(V1); // X & -1 == X + if (V2->isNullValue()) return const_cast(V2); // X & 0 == 0 + if (CE1->getOpcode() == Instruction::Cast && + isa(CE1->getOperand(0))) { + ConstantPointerRef *CPR =cast(CE1->getOperand(0)); + + // Functions are at least 4-byte aligned. If and'ing the address of a + // function with a constant < 4, fold it to zero. + if (const ConstantInt *CI = dyn_cast(V2)) + if (CI->getRawValue() < 4 && isa(CPR->getValue())) + return Constant::getNullValue(CI->getType()); + } + break; + case Instruction::Or: + if (V2->isNullValue()) return const_cast(V1); // X | 0 == X + if (cast(V2)->isAllOnesValue()) + return const_cast(V2); // X | -1 == -1 + break; + case Instruction::Xor: + if (V2->isNullValue()) return const_cast(V1); // X ^ 0 == X + break; + } + } + + } else if (const ConstantExpr *CE2 = dyn_cast(V2)) { + // If V2 is a constant expr and V1 isn't, flop them around and fold the + // other way if possible. + switch (Opcode) { + case Instruction::Add: + case Instruction::Mul: + case Instruction::And: + case Instruction::Or: + case Instruction::Xor: + case Instruction::SetEQ: + case Instruction::SetNE: + // No change of opcode required. + return ConstantFoldBinaryInstruction(Opcode, V2, V1); + + case Instruction::SetLT: + case Instruction::SetGT: + case Instruction::SetLE: + case Instruction::SetGE: + // Change the opcode as necessary to swap the operands. + Opcode = SetCondInst::getSwappedCondition((Instruction::BinaryOps)Opcode); + return ConstantFoldBinaryInstruction(Opcode, V2, V1); + + case Instruction::Shl: + case Instruction::Shr: + case Instruction::Sub: + case Instruction::Div: + case Instruction::Rem: + default: // These instructions cannot be flopped around. + break; + } } + return 0; } -ConstRules *ConstRules::getConstantExprRules() { - static EmptyRules CERules; - return &CERules; +Constant *llvm::ConstantFoldGetElementPtr(const Constant *C, + const std::vector &IdxList) { + if (IdxList.size() == 0 || + (IdxList.size() == 1 && IdxList[0]->isNullValue())) + return const_cast(C); + + if (C->isNullValue()) { + bool isNull = true; + for (unsigned i = 0, e = IdxList.size(); i != e; ++i) + if (!IdxList[i]->isNullValue()) { + isNull = false; + break; + } + if (isNull) { + std::vector VIdxList(IdxList.begin(), IdxList.end()); + const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), VIdxList, + true); + assert(Ty != 0 && "Invalid indices for GEP!"); + return ConstantPointerNull::get(PointerType::get(Ty)); + } + + if (IdxList.size() == 1) { + const Type *ElTy = cast(C->getType())->getElementType(); + if (unsigned ElSize = ElTy->getPrimitiveSize()) { + // gep null, C is equal to C*sizeof(nullty). If nullty is a known llvm + // type, we can statically fold this. + Constant *R = ConstantUInt::get(Type::UIntTy, ElSize); + R = ConstantExpr::getCast(R, IdxList[0]->getType()); + R = ConstantExpr::getMul(R, IdxList[0]); + return ConstantExpr::getCast(R, C->getType()); + } + } + } + + if (ConstantExpr *CE = dyn_cast(const_cast(C))) { + // Combine Indices - If the source pointer to this getelementptr instruction + // is a getelementptr instruction, combine the indices of the two + // getelementptr instructions into a single instruction. + // + if (CE->getOpcode() == Instruction::GetElementPtr) { + const Type *LastTy = 0; + for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE); + I != E; ++I) + LastTy = *I; + + if ((LastTy && isa(LastTy)) || IdxList[0]->isNullValue()) { + std::vector NewIndices; + NewIndices.reserve(IdxList.size() + CE->getNumOperands()); + for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i) + NewIndices.push_back(cast(CE->getOperand(i))); + + // Add the last index of the source with the first index of the new GEP. + // Make sure to handle the case when they are actually different types. + Constant *Combined = CE->getOperand(CE->getNumOperands()-1); + if (!IdxList[0]->isNullValue()) { // Otherwise it must be an array + const Type *IdxTy = Combined->getType(); + if (IdxTy != IdxList[0]->getType()) IdxTy = Type::LongTy; + Combined = + ConstantExpr::get(Instruction::Add, + ConstantExpr::getCast(IdxList[0], IdxTy), + ConstantExpr::getCast(Combined, IdxTy)); + } + + NewIndices.push_back(Combined); + NewIndices.insert(NewIndices.end(), IdxList.begin()+1, IdxList.end()); + return ConstantExpr::getGetElementPtr(CE->getOperand(0), NewIndices); + } + } + + // Implement folding of: + // int* getelementptr ([2 x int]* cast ([3 x int]* %X to [2 x int]*), + // long 0, long 0) + // To: int* getelementptr ([3 x int]* %X, long 0, long 0) + // + if (CE->getOpcode() == Instruction::Cast && IdxList.size() > 1 && + IdxList[0]->isNullValue()) + if (const PointerType *SPT = + dyn_cast(CE->getOperand(0)->getType())) + if (const ArrayType *SAT = dyn_cast(SPT->getElementType())) + if (const ArrayType *CAT = + dyn_cast(cast(C->getType())->getElementType())) + if (CAT->getElementType() == SAT->getElementType()) + return ConstantExpr::getGetElementPtr( + (Constant*)CE->getOperand(0), IdxList); + } + return 0; } +