#include "llvm/Analysis/LazyValueInfo.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/ValueLattice.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/AssemblyAnnotationWriter.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/ConstantRange.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/IR/ValueHandle.h"
#include "llvm/InitializePasses.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/FormattedStream.h"
#include "llvm/Support/KnownBits.h"
#include "llvm/Support/raw_ostream.h"
#include <map>

Include dependency graph for LazyValueInfo.cpp:

Namespaces
	llvm
	This file implements support for optimizing divisions by a constant.

Macros
#define	DEBUG_TYPE "lazy-value-info"

Functions
	INITIALIZE_PASS_BEGIN (LazyValueInfoWrapperPass, "lazy-value-info", "Lazy Value Information Analysis", false, true) INITIALIZE_PASS_END(LazyValueInfoWrapperPass

FunctionPass *	llvm::createLazyValueInfoPass ()
	createLazyValueInfoPass - This creates an instance of the LazyValueInfo pass. More...

static bool	hasSingleValue (const ValueLatticeElement &Val)
	Returns true if this lattice value represents at most one possible value. More...

static ValueLatticeElement	intersect (const ValueLatticeElement &A, const ValueLatticeElement &B)
	Combine two sets of facts about the same value into a single set of facts. More...

static ValueLatticeElement	getFromRangeMetadata (Instruction *BBI)

static void	AddNonNullPointer (Value *Ptr, NonNullPointerSet &PtrSet)

static void	AddNonNullPointersByInstruction (Instruction *I, NonNullPointerSet &PtrSet)

static ValueLatticeElement	getValueFromCondition (Value Val, Value Cond, bool isTrueDest=true)

static bool	matchICmpOperand (APInt &Offset, Value LHS, Value Val, ICmpInst::Predicate Pred)

static ValueLatticeElement	getValueFromSimpleICmpCondition (CmpInst::Predicate Pred, Value *RHS, const APInt &Offset)
	Get value range for a "(Val + Offset) Pred RHS" condition. More...

static ValueLatticeElement	getValueFromICmpCondition (Value Val, ICmpInst ICI, bool isTrueDest)

static ValueLatticeElement	getValueFromOverflowCondition (Value Val, WithOverflowInst WO, bool IsTrueDest)

static Optional< ValueLatticeElement >	getValueFromConditionImpl (Value Val, Value Cond, bool isTrueDest, bool isRevisit, SmallDenseMap< Value , ValueLatticeElement > &Visited, SmallVectorImpl< Value > &Worklist)

static bool	usesOperand (User Usr, Value Op)

static bool	isOperationFoldable (User *Usr)

static ValueLatticeElement	constantFoldUser (User Usr, Value Op, const APInt &OpConstVal, const DataLayout &DL)

static Optional< ValueLatticeElement >	getEdgeValueLocal (Value Val, BasicBlock BBFrom, BasicBlock *BBTo)
	Compute the value of Val on the edge BBFrom -> BBTo. More...

static LazyValueInfoImpl &	getImpl (void &PImpl, AssumptionCache AC, const Module *M)
	This lazily constructs the LazyValueInfoImpl. More...

static bool	isKnownNonConstant (Value *V)
	Returns true if we can statically tell that this value will never be a "useful" constant. More...

static LazyValueInfo::Tristate	getPredicateResult (unsigned Pred, Constant C, const ValueLatticeElement &Val, const DataLayout &DL, TargetLibraryInfo TLI)

	INITIALIZE_PASS_BEGIN (LazyValueInfoPrinter, "print-lazy-value-info", "Lazy Value Info Printer Pass", false, false) INITIALIZE_PASS_END(LazyValueInfoPrinter

Variables
static const unsigned	MaxProcessedPerValue = 500

lazy value	info

lazy value Lazy Value Information	Analysis

lazy value Lazy Value Information	false

print lazy value Lazy Value Info Printer	Pass

Macro Definition Documentation

◆ DEBUG_TYPE

#define DEBUG_TYPE "lazy-value-info"

Definition at line 45 of file LazyValueInfo.cpp.

Function Documentation

◆ AddNonNullPointer()

static void AddNonNullPointer	(	Value *	Ptr,
		NonNullPointerSet &	PtrSet
	)

static

Definition at line 631 of file LazyValueInfo.cpp.

References llvm::Type::getPointerAddressSpace(), llvm::Value::getType(), and llvm::getUnderlyingObject().

Referenced by AddNonNullPointersByInstruction().

◆ AddNonNullPointersByInstruction()

static void AddNonNullPointersByInstruction	(	Instruction *	I,
		NonNullPointerSet &	PtrSet
	)

static

Definition at line 637 of file LazyValueInfo.cpp.

References AddNonNullPointer(), I, llvm::ConstantInt::isZero(), MI, and S.

◆ constantFoldUser()

static ValueLatticeElement constantFoldUser	(	User *	Usr,
		Value *	Op,
		const APInt &	OpConstVal,
		const DataLayout &	DL
	)

static

Definition at line 1253 of file LazyValueInfo.cpp.

References assert(), DL, llvm::CastInst::getDestTy(), llvm::Constant::getIntegerValue(), llvm::BinaryOperator::getOpcode(), llvm::CastInst::getOpcode(), llvm::User::getOperand(), llvm::ValueLatticeElement::getOverdefined(), llvm::ValueLatticeElement::getRange(), isOperationFoldable(), llvm::SimplifyBinOp(), and llvm::SimplifyCastInst().

Referenced by getEdgeValueLocal().

◆ getEdgeValueLocal()

static Optional<ValueLatticeElement> getEdgeValueLocal	(	Value *	Val,
		BasicBlock *	BBFrom,
		BasicBlock *	BBTo
	)

static

Compute the value of Val on the edge BBFrom -> BBTo.

Returns false if Val is not constrained on the edge. Result is unspecified if return value is false.

Definition at line 1287 of file LazyValueInfo.cpp.

References llvm::ValueLatticeElement::asConstantInteger(), assert(), llvm::BitWidth, constantFoldUser(), llvm::ConstantRange::difference(), DL, llvm::ConstantInt::get(), llvm::ValueLatticeElement::get(), llvm::ValueLatticeElement::getConstantRange(), llvm::Value::getContext(), llvm::Module::getDataLayout(), llvm::Type::getInt1Ty(), llvm::Type::getIntegerBitWidth(), llvm::BasicBlock::getModule(), llvm::ValueLatticeElement::getRange(), llvm::BasicBlock::getTerminator(), llvm::Value::getType(), getValueFromCondition(), i, isOperationFoldable(), llvm::ValueLatticeElement::isOverdefined(), move, llvm::None, SI, llvm::ConstantRange::unionWith(), and usesOperand().

◆ getFromRangeMetadata()

static ValueLatticeElement getFromRangeMetadata ( Instruction * BBI )

static

Definition at line 554 of file LazyValueInfo.cpp.

References llvm::MCID::Call, llvm::getConstantRangeFromMetadata(), llvm::Instruction::getMetadata(), llvm::Instruction::getOpcode(), llvm::ValueLatticeElement::getOverdefined(), llvm::ValueLatticeElement::getRange(), llvm::Value::getType(), and llvm::SPII::Load.

◆ getImpl()

static LazyValueInfoImpl& getImpl	(	void *&	PImpl,
		AssumptionCache *	AC,
		const Module *	M
	)

static

This lazily constructs the LazyValueInfoImpl.

Definition at line 1506 of file LazyValueInfo.cpp.

References assert(), DL, llvm::Intrinsic::getName(), and M.

◆ getPredicateResult()

static LazyValueInfo::Tristate getPredicateResult	(	unsigned	Pred,
		Constant *	C,
		const ValueLatticeElement &	Val,
		const DataLayout &	DL,
		TargetLibraryInfo *	TLI
	)

static

◆ getValueFromCondition()

ValueLatticeElement getValueFromCondition	(	Value *	Val,
		Value *	Cond,
		bool	isTrueDest = `true`
	)

static

Definition at line 1206 of file LazyValueInfo.cpp.

References assert(), Cond, llvm::DenseMapBase< SmallDenseMap< KeyT, ValueT, 4, DenseMapInfo< KeyT >, llvm::detail::DenseMapPair< KeyT, ValueT > >, KeyT, ValueT, DenseMapInfo< KeyT >, llvm::detail::DenseMapPair< KeyT, ValueT > >::end(), llvm::DenseMapBase< SmallDenseMap< KeyT, ValueT, 4, DenseMapInfo< KeyT >, llvm::detail::DenseMapPair< KeyT, ValueT > >, KeyT, ValueT, DenseMapInfo< KeyT >, llvm::detail::DenseMapPair< KeyT, ValueT > >::find(), llvm::ValueLatticeElement::getOverdefined(), getValueFromConditionImpl(), and llvm::DenseMapBase< SmallDenseMap< KeyT, ValueT, 4, DenseMapInfo< KeyT >, llvm::detail::DenseMapPair< KeyT, ValueT > >, KeyT, ValueT, DenseMapInfo< KeyT >, llvm::detail::DenseMapPair< KeyT, ValueT > >::try_emplace().

Referenced by getEdgeValueLocal().

◆ getValueFromConditionImpl()

static Optional<ValueLatticeElement> getValueFromConditionImpl	(	Value *	Val,
		Value *	Cond,
		bool	isTrueDest,
		bool	isRevisit,
		SmallDenseMap< Value *, ValueLatticeElement > &	Visited,
		SmallVectorImpl< Value * > &	Worklist
	)

static

Definition at line 1154 of file LazyValueInfo.cpp.

References assert(), Cond, llvm::DenseMapBase< SmallDenseMap< KeyT, ValueT, 4, DenseMapInfo< KeyT >, llvm::detail::DenseMapPair< KeyT, ValueT > >, KeyT, ValueT, DenseMapInfo< KeyT >, llvm::detail::DenseMapPair< KeyT, ValueT > >::end(), llvm::DenseMapBase< SmallDenseMap< KeyT, ValueT, 4, DenseMapInfo< KeyT >, llvm::detail::DenseMapPair< KeyT, ValueT > >, KeyT, ValueT, DenseMapInfo< KeyT >, llvm::detail::DenseMapPair< KeyT, ValueT > >::find(), llvm::ExtractValueInst::getAggregateOperand(), llvm::ExtractValueInst::getNumIndices(), llvm::ValueLatticeElement::getOverdefined(), getValueFromICmpCondition(), getValueFromOverflowCondition(), llvm::ExtractValueInst::idx_begin(), intersect(), llvm::ValueLatticeElement::isOverdefined(), llvm::PatternMatch::m_LogicalAnd(), llvm::PatternMatch::m_LogicalOr(), llvm::PatternMatch::m_Value(), llvm::PatternMatch::match(), llvm::ValueLatticeElement::mergeIn(), and llvm::None.

Referenced by getValueFromCondition().

◆ getValueFromICmpCondition()

static ValueLatticeElement getValueFromICmpCondition	(	Value *	Val,
		ICmpInst *	ICI,
		bool	isTrueDest
	)

static

Definition at line 1076 of file LazyValueInfo.cpp.

References llvm::BitWidth, llvm::ConstantRange::fromKnownBits(), llvm::ValueLatticeElement::get(), llvm::Type::getIntegerBitWidth(), llvm::CmpInst::getInversePredicate(), llvm::ConstantRange::getNonEmpty(), llvm::ValueLatticeElement::getNot(), llvm::APInt::getOneBitSet(), llvm::User::getOperand(), llvm::ValueLatticeElement::getOverdefined(), llvm::CmpInst::getPredicate(), llvm::ValueLatticeElement::getRange(), llvm::Type::getScalarSizeInBits(), llvm::CmpInst::getSwappedPredicate(), llvm::Value::getType(), getValueFromSimpleICmpCondition(), llvm::APInt::getZero(), llvm::CmpInst::ICMP_EQ, llvm::CmpInst::ICMP_NE, llvm::ICmpInst::isEquality(), llvm::Type::isIntegerTy(), llvm::PatternMatch::m_And(), llvm::PatternMatch::m_APInt(), llvm::PatternMatch::m_Specific(), llvm::BitmaskEnumDetail::Mask(), llvm::PatternMatch::match(), matchICmpOperand(), Offset, llvm::KnownBits::One, and llvm::KnownBits::Zero.

Referenced by getValueFromConditionImpl().

◆ getValueFromOverflowCondition()

static ValueLatticeElement getValueFromOverflowCondition	(	Value *	Val,
		WithOverflowInst *	WO,
		bool	IsTrueDest
	)

static

Definition at line 1133 of file LazyValueInfo.cpp.

References llvm::BinaryOpIntrinsic::getBinaryOp(), llvm::BinaryOpIntrinsic::getLHS(), llvm::BinaryOpIntrinsic::getNoWrapKind(), llvm::ValueLatticeElement::getOverdefined(), llvm::ValueLatticeElement::getRange(), llvm::BinaryOpIntrinsic::getRHS(), llvm::ConstantRange::inverse(), llvm::PatternMatch::m_APInt(), llvm::ConstantRange::makeExactNoWrapRegion(), and llvm::PatternMatch::match().

Referenced by getValueFromConditionImpl().

◆ getValueFromSimpleICmpCondition()

static ValueLatticeElement getValueFromSimpleICmpCondition	(	CmpInst::Predicate	Pred,
		Value *	RHS,
		const APInt &	Offset
	)

static

Get value range for a "(Val + Offset) Pred RHS" condition.

Definition at line 1061 of file LazyValueInfo.cpp.

References llvm::getConstantRangeFromMetadata(), llvm::Type::getIntegerBitWidth(), llvm::ValueLatticeElement::getRange(), llvm::Value::getType(), I, llvm::ConstantRange::makeAllowedICmpRegion(), Offset, and llvm::ConstantRange::subtract().

Referenced by getValueFromICmpCondition().

◆ hasSingleValue()

static bool hasSingleValue ( const ValueLatticeElement & Val )

static

Returns true if this lattice value represents at most one possible value.

This is as precise as any lattice value can get while still representing reachable code.

Definition at line 71 of file LazyValueInfo.cpp.

References llvm::ValueLatticeElement::getConstantRange(), llvm::ValueLatticeElement::isConstant(), llvm::ValueLatticeElement::isConstantRange(), and llvm::ConstantRange::isSingleElement().

Referenced by intersect().

◆ INITIALIZE_PASS_BEGIN() [1/2]

INITIALIZE_PASS_BEGIN	(	LazyValueInfoPrinter	,
		"print-lazy-value-info"	,
		"Lazy Value Info Printer Pass"	,
		false	,
		false
	)

◆ INITIALIZE_PASS_BEGIN() [2/2]

INITIALIZE_PASS_BEGIN	(	LazyValueInfoWrapperPass	,
		"lazy-value-info"	,
		"Lazy Value Information Analysis"	,
		false	,
		true
	)

◆ intersect()

static ValueLatticeElement intersect	(	const ValueLatticeElement &	A,
		const ValueLatticeElement &	B
	)

static

Combine two sets of facts about the same value into a single set of facts.

Note that this method is not suitable for merging facts along different paths in a CFG; that's what the mergeIn function is for. This is for merging facts gathered about the same value at the same location through two independent means. Notes:

This method does not promise to return the most precise possible lattice value implied by A and B. It is allowed to return any lattice element which is at least as strong as either A or B (unless our facts conflict, see below).
Due to unreachable code, the intersection of two lattice values could be contradictory. If this happens, we return some valid lattice value so as not confuse the rest of LVI. Ideally, we'd always return Undefined, but we do not make this guarantee. TODO: This would be a useful enhancement.

Definition at line 96 of file LazyValueInfo.cpp.

References B, llvm::ValueLatticeElement::getRange(), hasSingleValue(), and move.

Referenced by getValueFromConditionImpl().

◆ isKnownNonConstant()

static bool isKnownNonConstant ( Value * V )

static

Returns true if we can statically tell that this value will never be a "useful" constant.

In practice, this means we've got something like an alloca or a malloc call for which a comparison against a constant can only be guarding dead code. Note that we are potentially giving up some precision in dead code (a constant result) in favour of avoiding a expensive search for a easily answered common query.

Definition at line 1574 of file LazyValueInfo.cpp.

References llvm::Value::stripPointerCasts().

Referenced by llvm::LazyValueInfo::getConstant().