CorrelatedValuePropagation.cpp File Reference

#include "llvm/Transforms/Scalar/CorrelatedValuePropagation.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/DomTreeUpdater.h"
#include "llvm/Analysis/GlobalsModRef.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/LazyValueInfo.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/ConstantRange.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InstrTypes.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Operator.h"
#include "llvm/IR/PassManager.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/Value.h"
#include "llvm/Pass.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/Local.h"
#include <cassert>
#include <utility>

Include dependency graph for CorrelatedValuePropagation.cpp:

Go to the source code of this file.

Macros
#define	DEBUG_TYPE   "correlated-value-propagation"

Functions
	STATISTIC (NumPhis, "Number of phis propagated")
	STATISTIC (NumPhiCommon, "Number of phis deleted via common incoming value")
	STATISTIC (NumSelects, "Number of selects propagated")
	STATISTIC (NumMemAccess, "Number of memory access targets propagated")
	STATISTIC (NumCmps, "Number of comparisons propagated")
	STATISTIC (NumReturns, "Number of return values propagated")
	STATISTIC (NumDeadCases, "Number of switch cases removed")
	STATISTIC (NumSDivs, "Number of sdiv converted to udiv")
	STATISTIC (NumUDivs, "Number of udivs whose width was decreased")
	STATISTIC (NumAShrs, "Number of ashr converted to lshr")
	STATISTIC (NumSRems, "Number of srem converted to urem")
	STATISTIC (NumOverflows, "Number of overflow checks removed")
	STATISTIC (NumSaturating, "Number of saturating arithmetics converted to normal arithmetics")
	INITIALIZE_PASS_BEGIN (CorrelatedValuePropagation, "correlated-propagation", "Value Propagation", false, false) INITIALIZE_PASS_END(CorrelatedValuePropagation
static bool	processSelect (SelectInst *S, LazyValueInfo *LVI)
static bool	simplifyCommonValuePhi (PHINode *P, LazyValueInfo *LVI, DominatorTree *DT)
	Try to simplify a phi with constant incoming values that match the edge values of a non-constant value on all other edges: bb0: isnull = icmp eq i8* x, null br i1 isnull, label bb2, label bb1 bb1: br label bb2 bb2: r = phi i8* [ x, bb1 ], [ null, bb0 ] –> r = x. More...
static bool	processPHI (PHINode *P, LazyValueInfo *LVI, DominatorTree *DT, const SimplifyQuery &SQ)
static bool	processMemAccess (Instruction *I, LazyValueInfo *LVI)
static bool	processCmp (CmpInst *Cmp, LazyValueInfo *LVI)
	See if LazyValueInfo's ability to exploit edge conditions or range information is sufficient to prove this comparison. More...
static bool	processSwitch (SwitchInst *I, LazyValueInfo *LVI, DominatorTree *DT)
	Simplify a switch instruction by removing cases which can never fire. More...
static bool	willNotOverflow (BinaryOpIntrinsic *BO, LazyValueInfo *LVI)
static void	processOverflowIntrinsic (WithOverflowInst *WO)
static void	processSaturatingInst (SaturatingInst *SI)
static bool	processCallSite (CallSite CS, LazyValueInfo *LVI)
	Infer nonnull attributes for the arguments at the specified callsite. More...
static bool	hasPositiveOperands (BinaryOperator *SDI, LazyValueInfo *LVI)
static bool	processUDivOrURem (BinaryOperator *Instr, LazyValueInfo *LVI)
	Try to shrink a udiv/urem's width down to the smallest power of two that's sufficient to contain its operands. More...
static bool	processSRem (BinaryOperator *SDI, LazyValueInfo *LVI)
static bool	processSDiv (BinaryOperator *SDI, LazyValueInfo *LVI)
	See if LazyValueInfo's ability to exploit edge conditions or range information is sufficient to prove the both operands of this SDiv are positive. More...
static bool	processAShr (BinaryOperator *SDI, LazyValueInfo *LVI)
static bool	processBinOp (BinaryOperator *BinOp, LazyValueInfo *LVI)
static Constant *	getConstantAt (Value *V, Instruction *At, LazyValueInfo *LVI)
static bool	runImpl (Function &F, LazyValueInfo *LVI, DominatorTree *DT, const SimplifyQuery &SQ)

Variables
static cl::opt< bool >	DontAddNoWrapFlags ("cvp-dont-add-nowrap-flags", cl::init(true))
correlated	propagation
correlated Value	Propagation
correlated Value	false

Macro Definition Documentation

DEBUG_TYPE

#define DEBUG_TYPE   "correlated-value-propagation"

Definition at line 52 of file CorrelatedValuePropagation.cpp.

Function Documentation

getConstantAt()

static Constant* getConstantAt ( Value *  V, Instruction *  At, LazyValueInfo *  LVI  )

static

Definition at line 676 of file CorrelatedValuePropagation.cpp.

References C, llvm::dyn_cast(), llvm::LazyValueInfo::getConstant(), llvm::Value::getContext(), llvm::ConstantInt::getFalse(), llvm::User::getOperand(), llvm::Instruction::getParent(), llvm::LazyValueInfo::getPredicateAt(), llvm::ConstantInt::getTrue(), llvm::LazyValueInfo::True, and llvm::LazyValueInfo::Unknown.

Referenced by runImpl().

hasPositiveOperands()

static bool hasPositiveOperands ( BinaryOperator *  SDI, LazyValueInfo *  LVI  )

static

Definition at line 523 of file CorrelatedValuePropagation.cpp.

References llvm::ConstantInt::get(), llvm::LazyValueInfo::getPredicateAt(), llvm::Value::getType(), llvm::CmpInst::ICMP_SGE, llvm::RISCVFenceField::O, llvm::User::operands(), and llvm::LazyValueInfo::True.

Referenced by processSDiv(), and processSRem().

INITIALIZE_PASS_BEGIN()

INITIALIZE_PASS_BEGIN	(	CorrelatedValuePropagation	,
		"correlated-propagation"	,
		"Value Propagation"	,
		false	,
		false
	)

processAShr()

static bool processAShr ( BinaryOperator *  SDI, LazyValueInfo *  LVI  )

static

Definition at line 615 of file CorrelatedValuePropagation.cpp.

References llvm::Instruction::eraseFromParent(), llvm::ConstantInt::get(), llvm::Instruction::getDebugLoc(), llvm::Value::getName(), llvm::User::getOperand(), llvm::LazyValueInfo::getPredicateAt(), llvm::Value::getType(), llvm::CmpInst::ICMP_SGE, llvm::Instruction::isExact(), llvm::Type::isVectorTy(), llvm::Value::replaceAllUsesWith(), and llvm::LazyValueInfo::True.

Referenced by runImpl().

processBinOp()

static bool processBinOp ( BinaryOperator *  BinOp, LazyValueInfo *  LVI  )

static

Definition at line 635 of file CorrelatedValuePropagation.cpp.

References llvm::ConstantRange::contains(), DontAddNoWrapFlags, llvm::LazyValueInfo::getConstantRange(), llvm::BinaryOperator::getOpcode(), llvm::User::getOperand(), llvm::Instruction::getParent(), llvm::Value::getType(), llvm::Instruction::hasNoSignedWrap(), llvm::Instruction::hasNoUnsignedWrap(), llvm::Type::isVectorTy(), llvm::ConstantRange::makeGuaranteedNoWrapRegion(), llvm::Instruction::setHasNoSignedWrap(), and llvm::Instruction::setHasNoUnsignedWrap().

Referenced by runImpl().

processCallSite()

static bool processCallSite ( CallSite  CS, LazyValueInfo *  LVI  )

static

Infer nonnull attributes for the arguments at the specified callsite.

Definition at line 453 of file CorrelatedValuePropagation.cpp.

References llvm::AttributeList::addParamAttribute(), llvm::CallSiteBase< FunTy, BBTy, ValTy, UserTy, UseTy, InstrTy, CallTy, InvokeTy, CallBrTy, IterTy >::arg_size(), llvm::CallSiteBase< FunTy, BBTy, ValTy, UserTy, UseTy, InstrTy, CallTy, InvokeTy, CallBrTy, IterTy >::args(), assert(), C, llvm::dyn_cast(), llvm::SmallVectorBase::empty(), llvm::LazyValueInfo::False, llvm::Attribute::get(), llvm::Use::get(), llvm::ConstantPointerNull::get(), llvm::CallSiteBase< FunTy, BBTy, ValTy, UserTy, UseTy, InstrTy, CallTy, InvokeTy, CallBrTy, IterTy >::getAttributes(), llvm::LazyValueInfo::getConstant(), llvm::Value::getContext(), llvm::CallSiteBase< FunTy, BBTy, ValTy, UserTy, UseTy, InstrTy, CallTy, InvokeTy, CallBrTy, IterTy >::getInstruction(), llvm::CallSiteBase< FunTy, BBTy, ValTy, UserTy, UseTy, InstrTy, CallTy, InvokeTy, CallBrTy, IterTy >::getOperandBundle(), llvm::CallSiteBase< FunTy, BBTy, ValTy, UserTy, UseTy, InstrTy, CallTy, InvokeTy, CallBrTy, IterTy >::getParent(), llvm::LazyValueInfo::getPredicateAt(), llvm::Value::getType(), llvm::CmpInst::ICMP_EQ, llvm::Type::isVectorTy(), llvm::LLVMContext::OB_deopt, llvm::CallSiteBase< FunTy, BBTy, ValTy, UserTy, UseTy, InstrTy, CallTy, InvokeTy, CallBrTy, IterTy >::paramHasAttr(), processOverflowIntrinsic(), processSaturatingInst(), llvm::SmallVectorTemplateBase< T, bool >::push_back(), llvm::Use::set(), llvm::CallSiteBase< FunTy, BBTy, ValTy, UserTy, UseTy, InstrTy, CallTy, InvokeTy, CallBrTy, IterTy >::setAttributes(), SI, and willNotOverflow().

Referenced by runImpl().

processCmp()

static bool processCmp ( CmpInst *  Cmp, LazyValueInfo *  LVI  )

static

See if LazyValueInfo's ability to exploit edge conditions or range information is sufficient to prove this comparison.

Even for local conditions, this can sometimes prove conditions instcombine can't by exploiting range information.

Definition at line 277 of file CorrelatedValuePropagation.cpp.

References C, llvm::dyn_cast(), llvm::Instruction::eraseFromParent(), llvm::ConstantInt::get(), llvm::Value::getContext(), llvm::Type::getInt1Ty(), llvm::User::getOperand(), llvm::Instruction::getParent(), llvm::CmpInst::getPredicate(), llvm::LazyValueInfo::getPredicateAt(), I, llvm::Value::replaceAllUsesWith(), and llvm::LazyValueInfo::Unknown.

Referenced by runImpl().

processMemAccess()

static bool processMemAccess ( Instruction *  I, LazyValueInfo *  LVI  )

static

Definition at line 256 of file CorrelatedValuePropagation.cpp.

References C, llvm::LazyValueInfo::getConstant(), llvm::Instruction::getParent(), llvm::getPointerOperand(), I, and llvm::User::replaceUsesOfWith().

Referenced by runImpl().

processOverflowIntrinsic()

static void processOverflowIntrinsic ( WithOverflowInst *  WO )

static

Definition at line 419 of file CorrelatedValuePropagation.cpp.

References B, llvm::IRBuilder< T, Inserter >::CreateBinOp(), llvm::IRBuilder< T, Inserter >::CreateInsertValue(), llvm::Instruction::eraseFromParent(), llvm::UndefValue::get(), llvm::BinaryOpIntrinsic::getBinaryOp(), llvm::Value::getContext(), llvm::ConstantInt::getFalse(), llvm::BinaryOpIntrinsic::getLHS(), llvm::Value::getName(), llvm::BinaryOpIntrinsic::getRHS(), llvm::Value::getType(), llvm::BinaryOpIntrinsic::isSigned(), and llvm::Value::replaceAllUsesWith().

Referenced by processCallSite().

processPHI()

static bool processPHI ( PHINode *  P, LazyValueInfo *  LVI, DominatorTree *  DT, const SimplifyQuery &  SQ  )

static

Definition at line 186 of file CorrelatedValuePropagation.cpp.

References C, llvm::dbgs(), llvm::dyn_cast(), llvm::Instruction::eraseFromParent(), llvm::LazyValueInfo::False, llvm::SelectInst::getCondition(), llvm::LazyValueInfo::getConstantOnEdge(), llvm::SelectInst::getFalseValue(), llvm::PHINode::getIncomingBlock(), llvm::PHINode::getIncomingValue(), llvm::PHINode::getNumIncomingValues(), llvm::Instruction::getParent(), llvm::LazyValueInfo::getPredicateOnEdge(), llvm::SelectInst::getTrueValue(), llvm::Value::getType(), llvm::CmpInst::ICMP_EQ, llvm::Type::isVectorTy(), LLVM_DEBUG, P, llvm::Value::replaceAllUsesWith(), llvm::PHINode::setIncomingValue(), SI, simplifyCommonValuePhi(), and llvm::SimplifyInstruction().

Referenced by runImpl().

processSaturatingInst()

static void processSaturatingInst ( SaturatingInst *  SI )

static

Definition at line 438 of file CorrelatedValuePropagation.cpp.

References llvm::BinaryOperator::Create(), llvm::Instruction::eraseFromParent(), llvm::BinaryOpIntrinsic::getBinaryOp(), llvm::Instruction::getDebugLoc(), llvm::BinaryOpIntrinsic::getLHS(), llvm::Value::getName(), llvm::BinaryOpIntrinsic::getRHS(), llvm::BinaryOpIntrinsic::isSigned(), llvm::Value::replaceAllUsesWith(), llvm::Instruction::setDebugLoc(), llvm::Instruction::setHasNoSignedWrap(), llvm::Instruction::setHasNoUnsignedWrap(), and SI.

Referenced by processCallSite().

processSDiv()

static bool processSDiv ( BinaryOperator *  SDI, LazyValueInfo *  LVI  )

static

See if LazyValueInfo's ability to exploit edge conditions or range information is sufficient to prove the both operands of this SDiv are positive.

If this is the case, replace the SDiv with a UDiv. Even for local conditions, this can sometimes prove conditions instcombine can't by exploiting range information.

Definition at line 597 of file CorrelatedValuePropagation.cpp.

References llvm::Instruction::eraseFromParent(), llvm::Instruction::getDebugLoc(), llvm::Value::getName(), llvm::User::getOperand(), llvm::Value::getType(), hasPositiveOperands(), llvm::Instruction::isExact(), llvm::Type::isVectorTy(), processUDivOrURem(), and llvm::Value::replaceAllUsesWith().

Referenced by runImpl().

processSelect()

static bool processSelect ( SelectInst *  S, LazyValueInfo *  LVI  )

static

Definition at line 107 of file CorrelatedValuePropagation.cpp.

References C, llvm::dyn_cast(), llvm::Instruction::eraseFromParent(), llvm::UndefValue::get(), llvm::SelectInst::getCondition(), llvm::LazyValueInfo::getConstant(), llvm::SelectInst::getFalseValue(), llvm::User::getOperand(), llvm::Instruction::getParent(), llvm::SelectInst::getTrueValue(), llvm::Value::getType(), llvm::ConstantInt::isOne(), llvm::Type::isVectorTy(), Other, llvm::Value::replaceAllUsesWith(), and std::swap().

Referenced by runImpl().

processSRem()

static bool processSRem ( BinaryOperator *  SDI, LazyValueInfo *  LVI  )

static

Definition at line 575 of file CorrelatedValuePropagation.cpp.

References llvm::Instruction::eraseFromParent(), llvm::Instruction::getDebugLoc(), llvm::Value::getName(), llvm::User::getOperand(), llvm::Value::getType(), hasPositiveOperands(), llvm::Type::isVectorTy(), processUDivOrURem(), and llvm::Value::replaceAllUsesWith().

Referenced by runImpl().

processSwitch()

static bool processSwitch ( SwitchInst *  I, LazyValueInfo *  LVI, DominatorTree *  DT  )

static

Simplify a switch instruction by removing cases which can never fire.

If the uselessness of a case could be determined locally then constant propagation would already have figured it out. Instead, walk the predecessors and statically evaluate cases based on information available on that edge. Cases that cannot fire no matter what the incoming edge can safely be removed. If a case fires on every incoming edge then the entire switch can be removed and replaced with a branch to the case destination.

Definition at line 311 of file CorrelatedValuePropagation.cpp.

References llvm::DomTreeUpdater::Lazy.

Referenced by runImpl().

processUDivOrURem()

static bool processUDivOrURem ( BinaryOperator *  Instr, LazyValueInfo *  LVI  )

static

Try to shrink a udiv/urem's width down to the smallest power of two that's sufficient to contain its operands.

Definition at line 535 of file CorrelatedValuePropagation.cpp.

References assert(), B, llvm::Instruction::eraseFromParent(), llvm::APInt::getActiveBits(), llvm::LazyValueInfo::getConstantRange(), llvm::Value::getContext(), llvm::Type::getIntegerBitWidth(), llvm::Type::getIntNTy(), llvm::Value::getName(), llvm::BinaryOperator::getOpcode(), llvm::User::getOperand(), llvm::Instruction::getParent(), llvm::Value::getType(), llvm::ConstantRange::getUnsignedMax(), llvm::Instruction::isExact(), llvm::Type::isVectorTy(), llvm::User::operands(), llvm::PowerOf2Ceil(), llvm::Value::replaceAllUsesWith(), and llvm::ConstantRange::unionWith().

Referenced by processSDiv(), processSRem(), and runImpl().

runImpl()

static bool runImpl ( Function &  F, LazyValueInfo *  LVI, DominatorTree *  DT, const SimplifyQuery &  SQ  )

static

Definition at line 699 of file CorrelatedValuePropagation.cpp.

References llvm::MCID::Add, C, llvm::MCID::Call, llvm::depth_first(), F(), llvm::getBestSimplifyQuery(), getConstantAt(), llvm::Function::getEntryBlock(), llvm::Instruction::getOpcode(), llvm::SPII::Load, processAShr(), processBinOp(), processCallSite(), processCmp(), processMemAccess(), processPHI(), processSDiv(), processSelect(), processSRem(), processSwitch(), processUDivOrURem(), llvm::MipsISD::Ret, runOnFunction(), llvm::MCID::Select, and llvm::SPII::Store.

Referenced by llvm::CorrelatedValuePropagationPass::run().

simplifyCommonValuePhi()

static bool simplifyCommonValuePhi ( PHINode *  P, LazyValueInfo *  LVI, DominatorTree *  DT  )

static

Try to simplify a phi with constant incoming values that match the edge values of a non-constant value on all other edges: bb0: isnull = icmp eq i8* x, null br i1 isnull, label bb2, label bb1 bb1: br label bb2 bb2: r = phi i8* [ x, bb1 ], [ null, bb0 ] –> r = x.

Definition at line 141 of file CorrelatedValuePropagation.cpp.

References C, llvm::DominatorTree::dominates(), llvm::SmallVectorBase::empty(), llvm::Instruction::eraseFromParent(), llvm::LazyValueInfo::getConstantOnEdge(), llvm::PHINode::getIncomingBlock(), llvm::PHINode::getIncomingValue(), llvm::PHINode::getNumIncomingValues(), llvm::Instruction::getParent(), llvm::SmallVectorTemplateBase< T >::push_back(), and llvm::Value::replaceAllUsesWith().

Referenced by processPHI().

STATISTIC() [1/13]

STATISTIC	(	NumPhis	,
		"Number of phis propagated"
	)

STATISTIC() [2/13]

STATISTIC	(	NumPhiCommon	,
		"Number of phis deleted via common incoming value"
	)

STATISTIC() [3/13]

STATISTIC	(	NumSelects	,
		"Number of selects propagated"
	)

STATISTIC() [4/13]

STATISTIC	(	NumMemAccess	,
		"Number of memory access targets propagated"
	)

STATISTIC() [5/13]

STATISTIC	(	NumCmps	,
		"Number of comparisons propagated"
	)

STATISTIC() [6/13]

STATISTIC	(	NumReturns	,
		"Number of return values propagated"
	)

STATISTIC() [7/13]

STATISTIC	(	NumDeadCases	,
		"Number of switch cases removed"
	)

STATISTIC() [8/13]

STATISTIC	(	NumSDivs	,
		"Number of sdiv converted to udiv"
	)

STATISTIC() [9/13]

STATISTIC	(	NumUDivs	,
		"Number of udivs whose width was decreased"
	)

STATISTIC() [10/13]

STATISTIC	(	NumAShrs	,
		"Number of ashr converted to lshr"
	)

STATISTIC() [11/13]

STATISTIC	(	NumSRems	,
		"Number of srem converted to urem"
	)

STATISTIC() [12/13]

STATISTIC	(	NumOverflows	,
		"Number of overflow checks removed"
	)

STATISTIC() [13/13]

STATISTIC	(	NumSaturating	,
		"Number of saturating arithmetics converted to normal arithmetics"
	)

willNotOverflow()

static bool willNotOverflow ( BinaryOpIntrinsic *  BO, LazyValueInfo *  LVI  )

static

Definition at line 409 of file CorrelatedValuePropagation.cpp.

References llvm::ConstantRange::contains(), llvm::BinaryOpIntrinsic::getBinaryOp(), llvm::LazyValueInfo::getConstantRange(), llvm::BinaryOpIntrinsic::getLHS(), llvm::BinaryOpIntrinsic::getNoWrapKind(), llvm::Instruction::getParent(), llvm::BinaryOpIntrinsic::getRHS(), and llvm::ConstantRange::makeGuaranteedNoWrapRegion().

Referenced by processCallSite(), shouldMergeGEPs(), and llvm::InstCombiner::visitInstruction().

Variable Documentation

DontAddNoWrapFlags

cl::opt<bool> DontAddNoWrapFlags("cvp-dont-add-nowrap-flags", cl::init(true))

static

Referenced by processBinOp().

false

correlated Value false

Definition at line 99 of file CorrelatedValuePropagation.cpp.

propagation

correlated propagation

Definition at line 99 of file CorrelatedValuePropagation.cpp.

Propagation

correlated Value Propagation

Definition at line 99 of file CorrelatedValuePropagation.cpp.