PromoteMemoryToRegister.cpp File Reference

#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/IteratedDominanceFrontier.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DIBuilder.h"
#include "llvm/IR/DebugInfo.h"
#include "llvm/IR/DebugProgramInstruction.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/InstrTypes.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/User.h"
#include "llvm/Support/Casting.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/PromoteMemToReg.h"
#include <algorithm>
#include <cassert>
#include <iterator>
#include <utility>
#include <vector>

Go to the source code of this file.

Macros
#define	DEBUG_TYPE   "mem2reg"

Functions
	STATISTIC (NumLocalPromoted, "Number of alloca's promoted within one block")
	STATISTIC (NumSingleStore, "Number of alloca's promoted with a single store")
	STATISTIC (NumDeadAlloca, "Number of dead alloca's removed")
	STATISTIC (NumPHIInsert, "Number of PHI nodes inserted")
static void	addAssumeNonNull (AssumptionCache *AC, LoadInst *LI)
	Given a LoadInst LI this adds assume(LI != null) after it.
static void	convertMetadataToAssumes (LoadInst *LI, Value *Val, const DataLayout &DL, AssumptionCache *AC, const DominatorTree *DT)
static void	removeIntrinsicUsers (AllocaInst *AI)
static bool	rewriteSingleStoreAlloca (AllocaInst *AI, AllocaInfo &Info, LargeBlockInfo &LBI, const DataLayout &DL, DominatorTree &DT, AssumptionCache *AC, SmallSet< DbgAssignIntrinsic *, 8 > *DbgAssignsToDelete, SmallSet< DbgVariableRecord *, 8 > *DVRAssignsToDelete)
	Rewrite as many loads as possible given a single store.
static bool	promoteSingleBlockAlloca (AllocaInst *AI, const AllocaInfo &Info, LargeBlockInfo &LBI, const DataLayout &DL, DominatorTree &DT, AssumptionCache *AC, SmallSet< DbgAssignIntrinsic *, 8 > *DbgAssignsToDelete, SmallSet< DbgVariableRecord *, 8 > *DVRAssignsToDelete)
	Many allocas are only used within a single basic block.
static void	updateForIncomingValueLocation (PHINode *PN, DebugLoc DL, bool ApplyMergedLoc)
	Update the debug location of a phi.

Macro Definition Documentation

DEBUG_TYPE

#define DEBUG_TYPE   "mem2reg"

Definition at line 57 of file PromoteMemoryToRegister.cpp.

Function Documentation

addAssumeNonNull()

static void addAssumeNonNull ( AssumptionCache *  AC, LoadInst *  LI  )

static

Given a LoadInst LI this adds assume(LI != null) after it.

Definition at line 442 of file PromoteMemoryToRegister.cpp.

References llvm::CallInst::Create(), llvm::Intrinsic::getDeclaration(), llvm::Instruction::getModule(), llvm::Constant::getNullValue(), llvm::Value::getType(), llvm::Instruction::insertAfter(), and llvm::AssumptionCache::registerAssumption().

Referenced by convertMetadataToAssumes().

convertMetadataToAssumes()

static void convertMetadataToAssumes ( LoadInst *  LI, Value *  Val, const DataLayout &  DL, AssumptionCache *  AC, const DominatorTree *  DT  )

static

Definition at line 453 of file PromoteMemoryToRegister.cpp.

References addAssumeNonNull(), DL, llvm::Instruction::getMetadata(), and llvm::isKnownNonZero().

Referenced by promoteSingleBlockAlloca(), and rewriteSingleStoreAlloca().

promoteSingleBlockAlloca()

static bool promoteSingleBlockAlloca ( AllocaInst *  AI, const AllocaInfo &  Info, LargeBlockInfo &  LBI, const DataLayout &  DL, DominatorTree &  DT, AssumptionCache *  AC, SmallSet< DbgAssignIntrinsic *, 8 > *  DbgAssignsToDelete, SmallSet< DbgVariableRecord *, 8 > *  DVRAssignsToDelete  )

static

Many allocas are only used within a single basic block.

If this is the case, avoid traversing the CFG and inserting a lot of potentially useless PHI nodes by just performing a single linear pass over the basic block using the Alloca.

If we cannot promote this alloca (because it is read before it is written), return false. This is necessary in cases where, due to control flow, the alloca is undefined only on some control flow paths. e.g. code like this is correct in LLVM IR: // A is an alloca with no stores so far for (...) { int t = *A; if (!first_iteration) use(t); *A = 42; }

Definition at line 619 of file PromoteMemoryToRegister.cpp.

References llvm::ConvertDebugDeclareToDebugValue(), convertMetadataToAssumes(), llvm::at::deleteAssignmentMarkers(), DL, llvm::Instruction::eraseFromParent(), llvm::UndefValue::get(), llvm::PoisonValue::get(), llvm::Instruction::getModule(), llvm::Value::getType(), I, Info, llvm::lower_bound(), llvm::make_early_inc_range(), llvm::SmallVectorTemplateBase< T, bool >::push_back(), llvm::Value::replaceAllUsesWith(), llvm::sort(), llvm::Value::use_empty(), llvm::Instruction::user_back(), and llvm::Value::users().

removeIntrinsicUsers()

static void removeIntrinsicUsers ( AllocaInst *  AI )

static

Definition at line 466 of file PromoteMemoryToRegister.cpp.

References llvm::Value::dropDroppableUse(), llvm::Instruction::eraseFromParent(), I, llvm::User::isDroppable(), llvm::make_early_inc_range(), and llvm::Value::uses().

rewriteSingleStoreAlloca()

static bool rewriteSingleStoreAlloca ( AllocaInst *  AI, AllocaInfo &  Info, LargeBlockInfo &  LBI, const DataLayout &  DL, DominatorTree &  DT, AssumptionCache *  AC, SmallSet< DbgAssignIntrinsic *, 8 > *  DbgAssignsToDelete, SmallSet< DbgVariableRecord *, 8 > *  DVRAssignsToDelete  )

static

Rewrite as many loads as possible given a single store.

When there is only a single store, we can use the domtree to trivially replace all of the dominated loads with the stored value. Do so, and return true if this has successfully promoted the alloca entirely. If this returns false there were some loads which were not dominated by the single store and thus must be phi-ed with undef. We fall back to the standard alloca promotion algorithm in that case.

Definition at line 509 of file PromoteMemoryToRegister.cpp.

References llvm::ConvertDebugDeclareToDebugValue(), convertMetadataToAssumes(), llvm::at::deleteAssignmentMarkers(), DL, llvm::DominatorTree::dominates(), llvm::Instruction::eraseFromParent(), llvm::PoisonValue::get(), llvm::Instruction::getModule(), llvm::User::getOperand(), llvm::Instruction::getParent(), llvm::Value::getType(), Info, llvm::make_early_inc_range(), llvm::Value::replaceAllUsesWith(), and llvm::Value::users().

STATISTIC() [1/4]

STATISTIC	(	NumDeadAlloca	,
		"Number of dead alloca's removed"
	)

STATISTIC() [2/4]

STATISTIC	(	NumLocalPromoted	,
		"Number of alloca's promoted within one block"
	)

STATISTIC() [3/4]

STATISTIC	(	NumPHIInsert	,
		"Number of PHI nodes inserted"
	)

STATISTIC() [4/4]

STATISTIC	(	NumSingleStore	,
		"Number of alloca's promoted with a single store"
	)

updateForIncomingValueLocation()

static void updateForIncomingValueLocation ( PHINode *  PN, DebugLoc  DL, bool  ApplyMergedLoc  )

static

Update the debug location of a phi.

ApplyMergedLoc indicates whether to create a merged location incorporating DL, or to set DL directly.

Definition at line 1068 of file PromoteMemoryToRegister.cpp.

References llvm::Instruction::applyMergedLocation(), DL, llvm::Instruction::getDebugLoc(), and llvm::Instruction::setDebugLoc().