InstCombinePHI.cpp File Reference

#include "InstCombineInternal.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Transforms/InstCombine/InstCombiner.h"
#include "llvm/Transforms/Utils/Local.h"
#include <optional>

Go to the source code of this file.

Classes
struct	llvm::DenseMapInfo< LoweredPHIRecord >

Namespaces
namespace	llvm
	This is an optimization pass for GlobalISel generic memory operations.

Macros
#define	DEBUG_TYPE   "instcombine"

Functions
	STATISTIC (NumPHIsOfInsertValues, "Number of phi-of-insertvalue turned into insertvalue-of-phis")
	STATISTIC (NumPHIsOfExtractValues, "Number of phi-of-extractvalue turned into extractvalue-of-phi")
	STATISTIC (NumPHICSEs, "Number of PHI's that got CSE'd")
static bool	isSafeAndProfitableToSinkLoad (LoadInst *L)
	Return true if we know that it is safe to sink the load out of the block that defines it.
static bool	isDeadPHICycle (PHINode *PN, SmallPtrSetImpl< PHINode * > &PotentiallyDeadPHIs)
	Return true if this PHI node is only used by a PHI node cycle that is dead.
static bool	PHIsEqualValue (PHINode *PN, Value *NonPhiInVal, SmallPtrSetImpl< PHINode * > &ValueEqualPHIs)
	Return true if this phi node is always equal to NonPhiInVal.
static ConstantInt *	getAnyNonZeroConstInt (PHINode &PN)
	Return an existing non-zero constant if this phi node has one, otherwise return constant 1.
static Value *	simplifyUsingControlFlow (InstCombiner &Self, PHINode &PN, const DominatorTree &DT)

Variables
static cl::opt< unsigned >	MaxNumPhis ("instcombine-max-num-phis", cl::init(512), cl::desc("Maximum number phis to handle in intptr/ptrint folding"))

Macro Definition Documentation

DEBUG_TYPE

#define DEBUG_TYPE   "instcombine"

Definition at line 28 of file InstCombinePHI.cpp.

Function Documentation

getAnyNonZeroConstInt()

static ConstantInt * getAnyNonZeroConstInt ( PHINode &  PN )

static

Return an existing non-zero constant if this phi node has one, otherwise return constant 1.

Definition at line 1024 of file InstCombinePHI.cpp.

References assert(), llvm::ConstantInt::get(), llvm::Value::getType(), and llvm::User::operands().

Referenced by llvm::InstCombinerImpl::visitPHINode().

isDeadPHICycle()

static bool isDeadPHICycle ( PHINode *  PN, SmallPtrSetImpl< PHINode * > &  PotentiallyDeadPHIs  )

static

Return true if this PHI node is only used by a PHI node cycle that is dead.

Definition at line 977 of file InstCombinePHI.cpp.

References llvm::Value::hasOneUse(), llvm::SmallPtrSetImpl< PtrType >::insert(), isDeadPHICycle(), llvm::SmallPtrSetImplBase::size(), llvm::Value::use_empty(), and llvm::Instruction::user_back().

Referenced by isDeadPHICycle(), and llvm::InstCombinerImpl::visitPHINode().

isSafeAndProfitableToSinkLoad()

static bool isSafeAndProfitableToSinkLoad ( LoadInst *  L )

static

Return true if we know that it is safe to sink the load out of the block that defines it.

This means that it must be obvious the value of the load is not changed from the point of the load to the end of the block it is in.

Finally, it is safe, but not profitable, to sink a load targeting a non-address-taken alloca. Doing so will cause us to not promote the alloca to a register.

Definition at line 621 of file InstCombinePHI.cpp.

References E, GEP, and SI.

Referenced by llvm::InstCombinerImpl::foldPHIArgLoadIntoPHI().

PHIsEqualValue()

static bool PHIsEqualValue ( PHINode *  PN, Value *  NonPhiInVal, SmallPtrSetImpl< PHINode * > &  ValueEqualPHIs  )

static

Return true if this phi node is always equal to NonPhiInVal.

This happens with mutually cyclic phi nodes like: z = some value; x = phi (y, z); y = phi (x, z)

Definition at line 999 of file InstCombinePHI.cpp.

References llvm::PHINode::incoming_values(), llvm::SmallPtrSetImpl< PtrType >::insert(), PHIsEqualValue(), and llvm::SmallPtrSetImplBase::size().

Referenced by PHIsEqualValue(), and llvm::InstCombinerImpl::visitPHINode().

simplifyUsingControlFlow()

static Value * simplifyUsingControlFlow ( InstCombiner &  Self, PHINode &  PN, const DominatorTree &  DT  )

static

Definition at line 1279 of file InstCombinePHI.cpp.

References llvm::all_of(), llvm::PHINode::blocks(), llvm::InstCombiner::Builder, llvm::CallingConv::C, Cond, Context, llvm::IRBuilderBase::CreateNot(), llvm::DominatorTree::dominates(), llvm::DenseMapBase< DerivedT, KeyT, ValueT, KeyInfoT, BucketT >::end(), llvm::BasicBlock::end(), llvm::DenseMapBase< DerivedT, KeyT, ValueT, KeyInfoT, BucketT >::find(), llvm::DomTreeNodeBase< NodeT >::getBlock(), llvm::Value::getContext(), llvm::ConstantInt::getFalse(), llvm::BasicBlock::getFirstInsertionPt(), llvm::DomTreeNodeBase< NodeT >::getIDom(), llvm::DominatorTreeBase< NodeT, IsPostDom >::getNode(), llvm::ConstantExpr::getNot(), llvm::Instruction::getParent(), llvm::ConstantInt::getTrue(), llvm::Value::getType(), llvm::PHINode::incoming_values(), llvm::DominatorTree::isReachableFromEntry(), llvm::User::operands(), llvm::IRBuilderBase::SetInsertPoint(), SI, and llvm::zip().

Referenced by llvm::InstCombinerImpl::visitPHINode().

STATISTIC() [1/3]

STATISTIC	(	NumPHICSEs	,
		"Number of PHI's that got CSE'd"
	)

STATISTIC() [2/3]

STATISTIC	(	NumPHIsOfExtractValues	,
		"Number of phi-of-extractvalue turned into extractvalue-of-phi"
	)

STATISTIC() [3/3]

STATISTIC	(	NumPHIsOfInsertValues	,
		"Number of phi-of-insertvalue turned into insertvalue-of-phis"
	)

Variable Documentation

MaxNumPhis

cl::opt< unsigned > MaxNumPhis("instcombine-max-num-phis", cl::init(512), cl::desc("Maximum number phis to handle in intptr/ptrint folding")) ( "instcombine-max-num-phis"  , cl::init(512)  , cl::desc("Maximum number phis to handle in intptr/ptrint folding")    )

static

Referenced by llvm::InstCombinerImpl::foldIntegerTypedPHI().