#include "llvm/IR/ConstantFold.h"
#include "llvm/ADT/APSInt.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GetElementPtrTypeIterator.h"
#include "llvm/IR/GlobalAlias.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Operator.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/Support/ErrorHandling.h"

Functions
static Constant *	BitCastConstantVector (Constant CV, VectorType DstTy)
	Convert the specified vector Constant node to the specified vector type.

static unsigned	foldConstantCastPair (unsigned opc, ConstantExpr Op, Type DstTy)
	This function determines which opcode to use to fold two constant cast expressions together.

static Constant *	FoldBitCast (Constant V, Type DestTy)

static Constant *	ExtractConstantBytes (Constant *C, unsigned ByteStart, unsigned ByteSize)
	V is an integer constant which only has a subset of its bytes used.

static FCmpInst::Predicate	evaluateFCmpRelation (Constant V1, Constant V2)
	This function determines if there is anything we can decide about the two constants provided.

static ICmpInst::Predicate	areGlobalsPotentiallyEqual (const GlobalValue GV1, const GlobalValue GV2)

static ICmpInst::Predicate	evaluateICmpRelation (Constant V1, Constant V2, bool isSigned)
	This function determines if there is anything we can decide about the two constants provided.

static Constant *	constantFoldCompareGlobalToNull (CmpInst::Predicate Predicate, Constant C1, Constant C2)

template<typename IndexTy >
static bool	isInBoundsIndices (ArrayRef< IndexTy > Idxs)
	Test whether the given sequence of normalized indices is "inbounds".

static bool	isIndexInRangeOfArrayType (uint64_t NumElements, const ConstantInt *CI)
	Test whether a given ConstantInt is in-range for a SequentialType.

static Constant *	foldGEPOfGEP (GEPOperator GEP, Type PointeeTy, bool InBounds, ArrayRef< Value * > Idxs)

Function Documentation

◆ areGlobalsPotentiallyEqual()

static ICmpInst::Predicate areGlobalsPotentiallyEqual	(	const GlobalValue *	GV1,
		const GlobalValue *	GV2
	)

static

Definition at line 1358 of file ConstantFold.cpp.

References llvm::Type::isEmptyTy(), and llvm::Type::isSized().

Referenced by evaluateICmpRelation().

◆ BitCastConstantVector()

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

static

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 43 of file ConstantFold.cpp.

References llvm::CallingConv::C, llvm::ConstantVector::get(), llvm::IntegerType::get(), llvm::ConstantInt::get(), llvm::Constant::getAllOnesValue(), llvm::ConstantExpr::getBitCast(), llvm::Value::getContext(), llvm::ConstantExpr::getExtractElement(), llvm::Constant::getNullValue(), llvm::ConstantVector::getSplat(), llvm::Constant::getSplatValue(), llvm::Value::getType(), llvm::Constant::isAllOnesValue(), and llvm::Constant::isNullValue().

Referenced by FoldBitCast().

◆ constantFoldCompareGlobalToNull()

static Constant * constantFoldCompareGlobalToNull	(	CmpInst::Predicate	Predicate,
		Constant *	C1,
		Constant *	C2
	)

static

Definition at line 1567 of file ConstantFold.cpp.

References llvm::PointerType::getAddressSpace(), llvm::Value::getContext(), llvm::ConstantInt::getFalse(), llvm::ConstantInt::getTrue(), llvm::GlobalValue::getType(), llvm::GlobalValue::hasExternalWeakLinkage(), llvm::Constant::isNullValue(), and llvm::NullPointerIsDefined().

Referenced by llvm::ConstantFoldCompareInstruction().

◆ evaluateFCmpRelation()

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

static

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 1305 of file ConstantFold.cpp.

References assert(), evaluateFCmpRelation(), llvm::ConstantExpr::getFCmp(), llvm::ConstantExpr::getOpcode(), and llvm::Value::getType().

Referenced by llvm::ConstantFoldCompareInstruction(), and evaluateFCmpRelation().

◆ evaluateICmpRelation()

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

static

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 1394 of file ConstantFold.cpp.

References areGlobalsPotentiallyEqual(), assert(), evaluateICmpRelation(), llvm::ConstantExpr::getICmp(), llvm::Constant::getNullValue(), llvm::ConstantExpr::getOpcode(), llvm::User::getOperand(), llvm::Value::getType(), llvm::GEPOperator::hasAllZeroIndices(), llvm::Type::isFPOrFPVectorTy(), llvm::GEPOperator::isInBounds(), llvm::Type::isIntOrPtrTy(), isSigned(), llvm::NullPointerIsDefined(), and pred.

Referenced by llvm::ConstantFoldCompareInstruction(), and evaluateICmpRelation().

◆ ExtractConstantBytes()

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

static

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 213 of file ConstantFold.cpp.

References assert(), llvm::CallingConv::C, ExtractConstantBytes(), llvm::IntegerType::get(), llvm::ConstantInt::get(), llvm::ConstantExpr::getAnd(), llvm::ConstantExpr::getLShr(), llvm::Constant::getNullValue(), llvm::ConstantExpr::getOr(), llvm::ConstantExpr::getTrunc(), llvm::Value::getType(), llvm::ConstantInt::getValue(), llvm::APInt::getZExtValue(), LHS, llvm::APInt::lshrInPlace(), RHS, llvm::APInt::uge(), and llvm::APInt::ule().

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

◆ FoldBitCast()

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

static

◆ foldConstantCastPair()

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

static

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

Parameters