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/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/DomTreeUpdater.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")
	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 *SI, LazyValueInfo *LVI, DominatorTree *DT)
	Simplify a switch instruction by removing cases which can never fire. More...
static bool	willNotOverflow (IntrinsicInst *II, LazyValueInfo *LVI)
static void	processOverflowIntrinsic (IntrinsicInst *II)
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	processAdd (BinaryOperator *AddOp, 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 >	DontProcessAdds ("cvp-dont-process-adds", 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 53 of file CorrelatedValuePropagation.cpp.

Function Documentation

getConstantAt()

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

static

Definition at line 660 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 494 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
	)

processAdd()

static bool processAdd ( BinaryOperator *  AddOp, LazyValueInfo *  LVI  )

static

Definition at line 606 of file CorrelatedValuePropagation.cpp.

References llvm::MCID::Add, llvm::ConstantRange::contains(), DontProcessAdds, llvm::LazyValueInfo::getConstantRange(), llvm::User::getOperand(), llvm::Instruction::getParent(), llvm::Value::getType(), llvm::Optional< T >::getValue(), llvm::Instruction::hasNoSignedWrap(), llvm::Instruction::hasNoUnsignedWrap(), llvm::ConstantRange::isEmptySet(), llvm::Type::isVectorTy(), llvm::ConstantRange::makeGuaranteedNoWrapRegion(), llvm::Instruction::setHasNoSignedWrap(), and llvm::Instruction::setHasNoUnsignedWrap().

Referenced by runImpl().

processAShr()

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

static

Definition at line 586 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().

processCallSite()

static bool processCallSite ( CallSite  CS, LazyValueInfo *  LVI  )

static

Infer nonnull attributes for the arguments at the specified callsite.

Definition at line 455 of file CorrelatedValuePropagation.cpp.

References llvm::AttributeList::addParamAttribute(), llvm::CallSiteBase< FunTy, BBTy, ValTy, UserTy, UseTy, InstrTy, CallTy, InvokeTy, IterTy >::arg_size(), llvm::CallSiteBase< FunTy, BBTy, ValTy, UserTy, UseTy, InstrTy, CallTy, InvokeTy, IterTy >::args(), assert(), llvm::dyn_cast(), llvm::SmallVectorBase::empty(), llvm::LazyValueInfo::False, llvm::Attribute::get(), llvm::ConstantPointerNull::get(), llvm::CallSiteBase< FunTy, BBTy, ValTy, UserTy, UseTy, InstrTy, CallTy, InvokeTy, IterTy >::getAttributes(), llvm::Value::getContext(), llvm::CallSiteBase< FunTy, BBTy, ValTy, UserTy, UseTy, InstrTy, CallTy, InvokeTy, IterTy >::getInstruction(), llvm::LazyValueInfo::getPredicateAt(), llvm::CmpInst::ICMP_EQ, llvm::Attribute::NonNull, llvm::CallSiteBase< FunTy, BBTy, ValTy, UserTy, UseTy, InstrTy, CallTy, InvokeTy, IterTy >::paramHasAttr(), processOverflowIntrinsic(), llvm::SmallVectorTemplateBase< T, bool >::push_back(), llvm::CallSiteBase< FunTy, BBTy, ValTy, UserTy, UseTy, InstrTy, CallTy, InvokeTy, IterTy >::setAttributes(), 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 276 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 255 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 ( IntrinsicInst *  II )

static

Definition at line 432 of file CorrelatedValuePropagation.cpp.

References B, llvm::IRBuilder< T, Inserter >::CreateAdd(), llvm::IRBuilder< T, Inserter >::CreateInsertValue(), llvm::IRBuilder< T, Inserter >::CreateSub(), llvm::Instruction::eraseFromParent(), llvm::UndefValue::get(), llvm::Value::getContext(), llvm::ConstantInt::getFalse(), llvm::IntrinsicInst::getIntrinsicID(), llvm::Value::getName(), llvm::User::getOperand(), llvm::Value::getType(), llvm_unreachable, llvm::Value::replaceAllUsesWith(), llvm::Intrinsic::sadd_with_overflow, llvm::Intrinsic::ssub_with_overflow, llvm::Intrinsic::uadd_with_overflow, and llvm::Intrinsic::usub_with_overflow.

Referenced by processCallSite().

processPHI()

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

static

Definition at line 185 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().

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 568 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 106 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 546 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 *  SI, 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 310 of file CorrelatedValuePropagation.cpp.

References llvm::SwitchInst::case_begin(), llvm::SwitchInst::case_end(), llvm::ConstantFoldTerminator(), llvm::DomTreeUpdater::deleteEdge(), llvm::LazyValueInfo::False, llvm::SwitchInst::getCondition(), llvm::SwitchInst::getNumCases(), llvm::Instruction::getParent(), getParent(), llvm::LazyValueInfo::getPredicateOnEdge(), llvm::CmpInst::ICMP_EQ, llvm::DomTreeUpdater::Lazy, llvm::pred_begin(), llvm::pred_end(), llvm::SwitchInst::removeCase(), llvm::BasicBlock::removePredecessor(), llvm::SwitchInst::setCondition(), llvm::successors(), llvm::LazyValueInfo::True, and llvm::LazyValueInfo::Unknown.

Referenced by llvm::collectCmpOps(), and 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 506 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 683 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, processAdd(), processAShr(), 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 140 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() [1/12]

STATISTIC	(	NumPhis	,
		"Number of phis propagated"
	)

STATISTIC() [2/12]

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

STATISTIC() [3/12]

STATISTIC	(	NumSelects	,
		"Number of selects propagated"
	)

STATISTIC() [4/12]

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

STATISTIC() [5/12]

STATISTIC	(	NumCmps	,
		"Number of comparisons propagated"
	)

STATISTIC() [6/12]

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

STATISTIC() [7/12]

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

STATISTIC() [8/12]

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

STATISTIC() [9/12]

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

STATISTIC() [10/12]

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

STATISTIC() [11/12]

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

STATISTIC() [12/12]

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

willNotOverflow()

static bool willNotOverflow ( IntrinsicInst *  II, LazyValueInfo *  LVI  )

static

Definition at line 403 of file CorrelatedValuePropagation.cpp.

References llvm::MCID::Add, llvm::ConstantRange::contains(), llvm::LazyValueInfo::getConstantRange(), llvm::IntrinsicInst::getIntrinsicID(), llvm::User::getOperand(), llvm::Instruction::getParent(), llvm::ConstantRange::isEmptySet(), llvm::ConstantRange::makeGuaranteedNoWrapRegion(), llvm::Intrinsic::sadd_with_overflow, llvm::Intrinsic::ssub_with_overflow, llvm::Intrinsic::uadd_with_overflow, and llvm::Intrinsic::usub_with_overflow.

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

Variable Documentation

DontProcessAdds

cl::opt<bool> DontProcessAdds("cvp-dont-process-adds", cl::init(true))

static

Referenced by processAdd().

false

correlated Value false

Definition at line 98 of file CorrelatedValuePropagation.cpp.

propagation

correlated propagation

Definition at line 98 of file CorrelatedValuePropagation.cpp.

Propagation

correlated Value Propagation

Definition at line 98 of file CorrelatedValuePropagation.cpp.