LoopPredication.cpp File Reference

#include "llvm/Transforms/Scalar/LoopPredication.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/BranchProbabilityInfo.h"
#include "llvm/Analysis/GuardUtils.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/LoopPass.h"
#include "llvm/Analysis/MemorySSA.h"
#include "llvm/Analysis/MemorySSAUpdater.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Analysis/ScalarEvolutionExpressions.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/IR/ProfDataUtils.h"
#include "llvm/Pass.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/GuardUtils.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/LoopUtils.h"
#include "llvm/Transforms/Utils/ScalarEvolutionExpander.h"
#include <optional>

Go to the source code of this file.

Macros
#define	DEBUG_TYPE   "loop-predication"

Functions
	STATISTIC (TotalConsidered, "Number of guards considered")
	STATISTIC (TotalWidened, "Number of checks widened")
static bool	isSafeToTruncateWideIVType (const DataLayout &DL, ScalarEvolution &SE, const LoopICmp LatchCheck, Type *RangeCheckType)
static std::optional< LoopICmp >	generateLoopLatchCheck (const DataLayout &DL, ScalarEvolution &SE, const LoopICmp LatchCheck, Type *RangeCheckType)
static void	normalizePredicate (ScalarEvolution *SE, Loop *L, LoopICmp &RC)
static BranchInst *	FindWidenableTerminatorAboveLoop (Loop *L, LoopInfo &LI)
	If we can (cheaply) find a widenable branch which controls entry into the loop, return it.
static const SCEV *	getMinAnalyzeableBackedgeTakenCount (ScalarEvolution &SE, DominatorTree &DT, Loop *L)
	Return the minimum of all analyzeable exit counts.

Variables
static cl::opt< bool >	EnableIVTruncation ("loop-predication-enable-iv-truncation", cl::Hidden, cl::init(true))
static cl::opt< bool >	EnableCountDownLoop ("loop-predication-enable-count-down-loop", cl::Hidden, cl::init(true))
static cl::opt< bool >	SkipProfitabilityChecks ("loop-predication-skip-profitability-checks", cl::Hidden, cl::init(false))
static cl::opt< float >	LatchExitProbabilityScale ("loop-predication-latch-probability-scale", cl::Hidden, cl::init(2.0), cl::desc("scale factor for the latch probability. Value should be greater " "than 1. Lower values are ignored"))
static cl::opt< bool >	PredicateWidenableBranchGuards ("loop-predication-predicate-widenable-branches-to-deopt", cl::Hidden, cl::desc("Whether or not we should predicate guards " "expressed as widenable branches to deoptimize blocks"), cl::init(true))
static cl::opt< bool >	InsertAssumesOfPredicatedGuardsConditions ("loop-predication-insert-assumes-of-predicated-guards-conditions", cl::Hidden, cl::desc("Whether or not we should insert assumes of conditions of " "predicated guards"), cl::init(true))

Macro Definition Documentation

DEBUG_TYPE

#define DEBUG_TYPE   "loop-predication"

Definition at line 205 of file LoopPredication.cpp.

Function Documentation

FindWidenableTerminatorAboveLoop()

BranchInst * FindWidenableTerminatorAboveLoop ( Loop * L, LoopInfo & LI )

static

If we can (cheaply) find a widenable branch which controls entry into the loop, return it.

Definition at line 973 of file LoopPredication.cpp.

References llvm::dyn_cast(), llvm::BasicBlock::getSinglePredecessor(), llvm::BasicBlock::getSingleSuccessor(), llvm::BranchInst::getSuccessor(), and llvm::isWidenableBranch().

generateLoopLatchCheck()

std::optional< LoopICmp > generateLoopLatchCheck ( const DataLayout & DL, ScalarEvolution & SE, const LoopICmp LatchCheck, Type * RangeCheckType )

static

Definition at line 446 of file LoopPredication.cpp.

References llvm::dbgs(), DL, llvm::dyn_cast(), llvm::ScalarEvolution::getTruncateExpr(), llvm::SCEVAddRecExpr::getType(), isSafeToTruncateWideIVType(), and LLVM_DEBUG.

getMinAnalyzeableBackedgeTakenCount()

const SCEV * getMinAnalyzeableBackedgeTakenCount ( ScalarEvolution & SE, DominatorTree & DT, Loop * L )

static

Return the minimum of all analyzeable exit counts.

This is an upper bound on the actual exit count. If there are not at least two analyzeable exits, returns SCEVCouldNotCompute.

Definition at line 1003 of file LoopPredication.cpp.

References assert(), llvm::DominatorTree::dominates(), llvm::ScalarEvolution::getCouldNotCompute(), llvm::ScalarEvolution::getExitCount(), llvm::ScalarEvolution::getUMinFromMismatchedTypes(), llvm::isa(), llvm::SmallVectorTemplateBase< T, bool >::push_back(), and llvm::SmallVectorTemplateCommon< T, typename >::size().

isSafeToTruncateWideIVType()

bool isSafeToTruncateWideIVType ( const DataLayout & DL, ScalarEvolution & SE, const LoopICmp LatchCheck, Type * RangeCheckType )

static

Definition at line 411 of file LoopPredication.cpp.

References assert(), DL, llvm::dyn_cast(), EnableIVTruncation, llvm::ScalarEvolution::getMonotonicPredicateType(), llvm::SCEVAddRecExpr::getStart(), and llvm::SCEVAddRecExpr::getType().

Referenced by generateLoopLatchCheck().

normalizePredicate()

void normalizePredicate ( ScalarEvolution * SE, Loop * L, LoopICmp & RC )

static

Definition at line 638 of file LoopPredication.cpp.

References llvm::SCEVAddRecExpr::getStart(), llvm::SCEVAddRecExpr::getStepRecurrence(), llvm::CmpInst::ICMP_NE, llvm::CmpInst::ICMP_UGE, llvm::CmpInst::ICMP_ULE, llvm::CmpInst::ICMP_ULT, llvm::ICmpInst::isEquality(), llvm::ScalarEvolution::isKnownPredicate(), and llvm::SCEV::isOne().

STATISTIC() [1/2]

STATISTIC	(	TotalConsidered	,
		"Number of guards considered"	)

STATISTIC() [2/2]

STATISTIC	(	TotalWidened	,
		"Number of checks widened"	)

Variable Documentation

EnableCountDownLoop

cl::opt< bool > EnableCountDownLoop("loop-predication-enable-count-down-loop", cl::Hidden, cl::init(true)) ( "loop-predication-enable-count-down-loop" , cl::Hidden , cl::init(true)  )

static

EnableIVTruncation

cl::opt< bool > EnableIVTruncation("loop-predication-enable-iv-truncation", cl::Hidden, cl::init(true)) ( "loop-predication-enable-iv-truncation" , cl::Hidden , cl::init(true)  )

static

Referenced by isSafeToTruncateWideIVType().

InsertAssumesOfPredicatedGuardsConditions

cl::opt< bool > InsertAssumesOfPredicatedGuardsConditions("loop-predication-insert-assumes-of-predicated-guards-conditions", cl::Hidden, cl::desc("Whether or not we should insert assumes of conditions of " "predicated guards"), cl::init(true)) ( "loop-predication-insert-assumes-of-predicated-guards-conditions" , cl::Hidden , cl::desc("Whether or not we should insert assumes of conditions of " "predicated guards") , cl::init(true)  )

static

LatchExitProbabilityScale

cl::opt< float > LatchExitProbabilityScale("loop-predication-latch-probability-scale", cl::Hidden, cl::init(2.0), cl::desc("scale factor for the latch probability. Value should be greater " "than 1. Lower values are ignored")) ( "loop-predication-latch-probability-scale" , cl::Hidden , cl::init(2.0) , cl::desc("scale factor for the latch probability. Value should be greater " "than 1. Lower values are ignored")  )

static

PredicateWidenableBranchGuards

cl::opt< bool > PredicateWidenableBranchGuards("loop-predication-predicate-widenable-branches-to-deopt", cl::Hidden, cl::desc("Whether or not we should predicate guards " "expressed as widenable branches to deoptimize blocks"), cl::init(true)) ( "loop-predication-predicate-widenable-branches-to-deopt" , cl::Hidden , cl::desc("Whether or not we should predicate guards " "expressed as widenable branches to deoptimize blocks") , cl::init(true)  )

static

SkipProfitabilityChecks

cl::opt< bool > SkipProfitabilityChecks("loop-predication-skip-profitability-checks", cl::Hidden, cl::init(false)) ( "loop-predication-skip-profitability-checks" , cl::Hidden , cl::init(false)  )

static