#include "ConstantFold.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalAlias.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Operator.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Support/MathExtras.h"
#include <limits>

Include dependency graph for ConstantFold.cpp:

Functions
static Constant *	BitCastConstantVector (Constant CV, VectorType DstTy)

static unsigned	foldConstantCastPair (unsigned opc, ConstantExpr Op, Type DstTy)
	Determine if it is valid to fold a cast of a cast. More...

static Constant *	FoldBitCast (Constant V, Type DestTy)

static Constant *	ExtractConstantBytes (Constant *C, unsigned ByteStart, unsigned ByteSize)

static Constant *	getFoldedSizeOf (Type Ty, Type DestTy, bool Folded)

static Constant *	getFoldedAlignOf (Type Ty, Type DestTy, bool Folded)

static Constant *	getFoldedOffsetOf (Type Ty, Constant FieldNo, Type *DestTy, bool Folded)

static bool	isMaybeZeroSizedType (Type *Ty)

static int	IdxCompare (Constant C1, Constant C2, Type *ElTy)

static FCmpInst::Predicate	evaluateFCmpRelation (Constant V1, Constant V2)

static ICmpInst::Predicate	evaluateICmpRelation (Constant V1, Constant V2, bool isSigned)

template<typename IndexTy >
static bool	isInBoundsIndices (ArrayRef< IndexTy > Idxs)

static bool	isIndexInRangeOfSequentialType (const SequentialType STy, const ConstantInt CI)
	Test whether a given ConstantInt is in-range for a SequentialType. More...

template<typename IndexTy >
static Constant *	ConstantFoldGetElementPtrImpl (Constant *C, bool inBounds, ArrayRef< IndexTy > Idxs)

Function Documentation

static Constant* BitCastConstantVector	(	Constant *	CV,
		VectorType *	DstTy
	)

static

BitCastConstantVector - Convert the specified vector Constant node to the specified vector type. At this point, we know that the elements of the input vector constant are all simple integer or FP values.

Definition at line 44 of file ConstantFold.cpp.

References llvm::CallingConv::C, llvm::IntegerType::get(), llvm::ConstantInt::get(), llvm::ConstantVector::get(), llvm::Constant::getAllOnesValue(), llvm::ConstantExpr::getBitCast(), llvm::Value::getContext(), llvm::SequentialType::getElementType(), llvm::ConstantExpr::getExtractElement(), llvm::Constant::getNullValue(), llvm::VectorType::getNumElements(), llvm::Value::getType(), llvm::Type::getVectorNumElements(), llvm::Constant::isAllOnesValue(), llvm::Constant::isNullValue(), and llvm::SmallVectorTemplateBase< T, isPodLike< T >::value >::push_back().

Referenced by FoldBitCast().

template<typename IndexTy >

static Constant* ConstantFoldGetElementPtrImpl	(	Constant *	C,
		bool	inBounds,
		ArrayRef< IndexTy >	Idxs
	)

static

Definition at line 1934 of file ConstantFold.cpp.

Referenced by llvm::ConstantFoldGetElementPtr().

static FCmpInst::Predicate evaluateFCmpRelation	(	Constant *	V1,
		Constant *	V2
	)

static

evaluateFCmpRelation - This function determines if there is anything we can decide about the two constants provided. This doesn't need to handle simple things like ConstantFP comparisons, but should instead handle ConstantExprs. If we can determine that the two constants have a particular relation to each other, we should return the corresponding FCmpInst predicate, otherwise return FCmpInst::BAD_FCMP_PREDICATE. This is used below in ConstantFoldCompareInstruction.

To simplify this code we canonicalize the relation so that the first operand is always the most "complex" of the two. We consider ConstantFP to be the simplest, and ConstantExprs to be the most complex.

Definition at line 1273 of file ConstantFold.cpp.

References llvm::CmpInst::BAD_FCMP_PREDICATE, llvm::dyn_cast(), llvm::CmpInst::FCMP_OEQ, llvm::CmpInst::FCMP_OGT, llvm::CmpInst::FCMP_OLT, llvm::ConstantExpr::getFCmp(), llvm::ConstantExpr::getOpcode(), llvm::CmpInst::getSwappedPredicate(), llvm::Value::getType(), and llvm::ConstantInt::isZero().

Referenced by llvm::ConstantFoldCompareInstruction().

static ICmpInst::Predicate evaluateICmpRelation	(	Constant *	V1,
		Constant *	V2,
		bool	isSigned
	)

static

evaluateICmpRelation - 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 ConstantExprs and GlobalValues. If we can determine that the two constants have a particular relation to each other, we should return the corresponding ICmp predicate, otherwise return ICmpInst::BAD_ICMP_PREDICATE.

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 GlobalValues, followed by ConstantExpr's (the most complex).

Definition at line 1337 of file ConstantFold.cpp.

References llvm::CmpInst::BAD_ICMP_PREDICATE, llvm::dyn_cast(), llvm::gep_type_begin(), llvm::ConstantExpr::getICmp(), llvm::generic_gep_type_iterator< ItTy >::getIndexedType(), llvm::Constant::getNullValue(), llvm::User::getNumOperands(), llvm::ConstantExpr::getOpcode(), llvm::User::getOperand(), llvm::CmpInst::getSwappedPredicate(), llvm::Value::getType(), llvm::CmpInst::ICMP_EQ, llvm::CmpInst::ICMP_NE, llvm::CmpInst::ICMP_SGE, llvm::CmpInst::ICMP_SGT, llvm::CmpInst::ICMP_SLE, llvm::CmpInst::ICMP_SLT, llvm::CmpInst::ICMP_UGE, llvm::CmpInst::ICMP_UGT, llvm::CmpInst::ICMP_ULE, llvm::CmpInst::ICMP_ULT, IdxCompare(), llvm::ConstantExpr::isGEPWithNoNotionalOverIndexing(), llvm::Type::isIntegerTy(), llvm::Constant::isNullValue(), llvm::Type::isPointerTy(), llvm::ConstantInt::isZero(), and llvm::NVPTX::PTXLdStInstCode::V2.

Referenced by llvm::ConstantFoldCompareInstruction().

static Constant* ExtractConstantBytes	(	Constant *	C,
		unsigned	ByteStart,
		unsigned	ByteSize
	)

static

ExtractConstantBytes - V is an integer constant which only has a subset of its bytes used. The bytes used are indicated by ByteStart (which is the first byte used, counting from the least significant byte) and ByteSize, which is the number of bytes used.

This function analyzes the specified constant to see if the specified byte range can be returned as a simplified constant. If so, the constant is returned, otherwise null is returned.

Definition at line 197 of file ConstantFold.cpp.

References llvm::APIntOps::And(), llvm::CallingConv::C, llvm::dyn_cast(), llvm::IntegerType::get(), llvm::ConstantInt::get(), llvm::ConstantExpr::getAnd(), getBitWidth(), llvm::Value::getContext(), llvm::ConstantExpr::getLShr(), llvm::Constant::getNullValue(), llvm::ConstantExpr::getOpcode(), llvm::User::getOperand(), llvm::ConstantExpr::getOr(), llvm::ConstantExpr::getTrunc(), llvm::Value::getType(), llvm::ConstantInt::getZExtValue(), llvm::Type::isIntegerTy(), llvm::Constant::isNullValue(), llvm::APInt::lshr(), llvm::APIntOps::Or(), and llvm::APInt::trunc().

Referenced by llvm::ConstantFoldCastInstruction().

static Constant* FoldBitCast	(	Constant *	V,
		Type *	DestTy
	)

static

static unsigned foldConstantCastPair	(	unsigned	opc,
		ConstantExpr *	Op,
		Type *	DstTy
	)

static

Determine if it is valid to fold a cast of a cast.

This function determines which opcode to use to fold two constant cast expressions together. It uses CastInst::isEliminableCastPair to determine the opcode. Consequently its just a wrapper around that function.

Parameters

opc	opcode of the second cast constant expression
Op	the first cast constant expression
DstTy	destination type of the first cast

Definition at line 75 of file ConstantFold.cpp.

References llvm::Type::getContext(), llvm::Type::getInt64Ty(), llvm::ConstantExpr::getOpcode(), llvm::User::getOperand(), llvm::Value::getType(), llvm::Instruction::isCast(), llvm::ConstantExpr::isCast(), llvm::CastInst::isEliminableCastPair(), and llvm::Type::isFirstClassType().

Referenced by llvm::ConstantFoldCastInstruction().

static Constant* getFoldedAlignOf	(	Type *	Ty,
		Type *	DestTy,
		bool	Folded
	)

static

getFoldedAlignOf - Return a ConstantExpr with type DestTy for alignof on Ty, with any known factors factored out. If Folded is false, return null if no factoring was possible, to avoid endlessly bouncing an unfoldable expression back into the top-level folder.

Definition at line 394 of file ConstantFold.cpp.

References llvm::CallingConv::C, llvm::IntegerType::get(), llvm::ConstantInt::get(), llvm::PointerType::get(), llvm::ConstantExpr::getAlignOf(), llvm::ConstantExpr::getCast(), and llvm::CastInst::getCastOpcode().

Referenced by llvm::ConstantFoldCastInstruction().

static Constant* getFoldedOffsetOf	(	Type *	Ty,
		Constant *	FieldNo,
		Type *	DestTy,
		bool	Folded
	)

static

getFoldedOffsetOf - Return a ConstantExpr with type DestTy for offsetof on Ty and FieldNo, with any known factors factored out. If Folded is false, return null if no factoring was possible, to avoid endlessly bouncing an unfoldable expression back into the top-level folder.

Definition at line 460 of file ConstantFold.cpp.

References llvm::CallingConv::C, llvm::ConstantExpr::getCast(), llvm::CastInst::getCastOpcode(), getFoldedSizeOf(), llvm::ConstantExpr::getNUWMul(), llvm::ConstantExpr::getOffsetOf(), and N.

Referenced by llvm::ConstantFoldCastInstruction().

static Constant* getFoldedSizeOf	(	Type *	Ty,
		Type *	DestTy,
		bool	Folded
	)

static

getFoldedSizeOf - Return a ConstantExpr with type DestTy for sizeof on Ty, with any known factors factored out. If Folded is false, return null if no factoring was possible, to avoid endlessly bouncing an unfoldable expression back into the top-level folder.

Definition at line 337 of file ConstantFold.cpp.

References llvm::CallingConv::C, llvm::IntegerType::get(), llvm::ConstantInt::get(), llvm::PointerType::get(), llvm::ConstantExpr::getCast(), llvm::CastInst::getCastOpcode(), llvm::Constant::getNullValue(), llvm::ConstantExpr::getNUWMul(), llvm::ConstantExpr::getSizeOf(), and N.

Referenced by llvm::ConstantFoldCastInstruction(), and getFoldedOffsetOf().

static int IdxCompare	(	Constant *	C1,
		Constant *	C2,
		Type *	ElTy
	)

static

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.

Definition at line 1230 of file ConstantFold.cpp.

References llvm::Value::getContext(), llvm::Type::getInt64Ty(), llvm::ConstantExpr::getSExt(), llvm::Value::getType(), llvm::Type::isIntegerTy(), and isMaybeZeroSizedType().

Referenced by evaluateICmpRelation().

template<typename IndexTy >

static bool isInBoundsIndices ( ArrayRef< IndexTy > Idxs )

static

isInBoundsIndices - Test whether the given sequence of normalized indices is "inbounds".

Definition at line 1885 of file ConstantFold.cpp.

References llvm::ArrayRef< T >::empty(), and llvm::ArrayRef< T >::size().

Referenced by ConstantFoldGetElementPtrImpl().