GlobalOpt.cpp File Reference

#include "llvm/Transforms/IPO.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Instructions.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
#include "llvm/Support/Debug.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringExtras.h"
#include <set>
#include <algorithm>

Include dependency graph for GlobalOpt.cpp:

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Classes

struct GlobalStatus

Defines

#define DEBUG_TYPE "globalopt"

Functions

ModulePass * llvm::createGlobalOptimizerPass ()

static bool ConstantIsDead (Constant *C)

static bool AnalyzeGlobal (Value *V, GlobalStatus &GS, std::set< PHINode * > &PHIUsers)

static Constant * getAggregateConstantElement (Constant *Agg, Constant *Idx)

static Constant * TraverseGEPInitializer (User *GEP, Constant *Init)

static bool CleanupConstantGlobalUsers (Value *V, Constant *Init)

static GlobalVariable * SRAGlobal (GlobalVariable *GV)

static bool AllUsesOfValueWillTrapIfNull (Value *V)

static bool AllUsesOfLoadedValueWillTrapIfNull (GlobalVariable *GV)

static bool OptimizeAwayTrappingUsesOfValue (Value *V, Constant *NewV)

static bool OptimizeAwayTrappingUsesOfLoads (GlobalVariable *GV, Constant *LV)

static void ConstantPropUsersOf (Value *V)

static GlobalVariable * OptimizeGlobalAddressOfMalloc (GlobalVariable *GV, MallocInst *MI)

static bool ValueIsOnlyUsedLocallyOrStoredToOneGlobal (Instruction *V, GlobalVariable *GV)

static bool OptimizeOnceStoredGlobal (GlobalVariable *GV, Value *StoredOnceVal, Module::giterator &GVI, TargetData &TD)

Define Documentation

#define DEBUG_TYPE "globalopt"

Definition at line 16 of file GlobalOpt.cpp.

Function Documentation

static bool AllUsesOfLoadedValueWillTrapIfNull ( GlobalVariable * GV ) [static]

AllUsesOfLoadedValueWillTrapIfNull - Return true if all uses of any loads from GV will trap if the loaded value is null. Note that this also permits comparisons of the loaded value against null, as a special case.
Definition at line 480 of file GlobalOpt.cpp.
References AllUsesOfValueWillTrapIfNull(), E, llvm::Value::use_begin(), and llvm::Value::use_end().
Referenced by OptimizeOnceStoredGlobal().

static bool AllUsesOfValueWillTrapIfNull ( Value * V ) [static]

AllUsesOfValueWillTrapIfNull - Return true if all users of the specified value will trap if the value is dynamically null.
Definition at line 444 of file GlobalOpt.cpp.
References E, llvm::Value::use_begin(), and llvm::Value::use_end().
Referenced by AllUsesOfLoadedValueWillTrapIfNull().

static bool AnalyzeGlobal ( Value * V,

GlobalStatus & GS,

std::set< PHINode * > & PHIUsers

) [static]

AnalyzeGlobal - Look at all uses of the global and fill in the GlobalStatus structure. If the global has its address taken, return true to indicate we can't do anything with it.
Definition at line 124 of file GlobalOpt.cpp.
References C, ConstantIsDead(), E, I, GlobalStatus::isInitializerStored, GlobalStatus::isLoaded, GlobalStatus::isNotSuitableForSRA, GlobalStatus::isStored, GlobalStatus::isStoredOnce, llvm::Select, GlobalStatus::StoredOnceValue, GlobalStatus::StoredType, llvm::Value::use_begin(), and llvm::Value::use_end().

static bool CleanupConstantGlobalUsers ( Value * V,

Constant * Init

) [static]

CleanupConstantGlobalUsers - We just marked GV constant. Loop over all users of the global, cleaning up the obvious ones. This is largely just a quick scan over the use list to clean up the easy and obvious cruft. This returns true if it made a change.
Definition at line 273 of file GlobalOpt.cpp.
References C, ConstantIsDead(), E, TraverseGEPInitializer(), U, llvm::Value::use_begin(), and llvm::Value::use_end().
Referenced by OptimizeAwayTrappingUsesOfLoads().

static bool ConstantIsDead ( Constant * C ) [static]

ConstantIsDead - Return true if the specified constant is (transitively) dead. The constant may be used by other constants (e.g. constant arrays and constant exprs) as long as they are dead, but it cannot be used by anything else.
Definition at line 108 of file GlobalOpt.cpp.
References E.
Referenced by AnalyzeGlobal(), and CleanupConstantGlobalUsers().

static void ConstantPropUsersOf ( Value * V ) [static]

ConstantPropUsersOf - Walk the use list of V, constant folding all of the instructions that are foldable.
Definition at line 608 of file GlobalOpt.cpp.
References llvm::ConstantFoldInstruction(), E, I, llvm::Value::use_begin(), and llvm::Value::use_end().
Referenced by OptimizeGlobalAddressOfMalloc().

static Constant* getAggregateConstantElement ( Constant * Agg,

Constant * Idx

) [static]

Definition at line 223 of file GlobalOpt.cpp.
References llvm::ConstantIntegral::getRawValue().
Referenced by SRAGlobal(), and TraverseGEPInitializer().

static bool OptimizeAwayTrappingUsesOfLoads ( GlobalVariable * GV,

Constant * LV

) [static]

OptimizeAwayTrappingUsesOfLoads - The specified global has only one non-null value stored into it. If there are uses of the loaded value that would trap if the loaded value is dynamically null, then we know that they cannot be reachable with a null optimize away the load.
Definition at line 560 of file GlobalOpt.cpp.
References CleanupConstantGlobalUsers(), DEBUG, E, llvm::GlobalVariable::eraseFromParent(), llvm::Instruction::eraseFromParent(), NumDeleted, NumGlobUses, OptimizeAwayTrappingUsesOfValue(), llvm::Value::use_begin(), llvm::Value::use_empty(), and llvm::Value::use_end().
Referenced by OptimizeOnceStoredGlobal().

static bool OptimizeAwayTrappingUsesOfValue ( Value * V,

Constant * NewV

) [static]

Definition at line 496 of file GlobalOpt.cpp.
References C, E, llvm::Value::getType(), I, llvm::Value::use_begin(), and llvm::Value::use_end().
Referenced by OptimizeAwayTrappingUsesOfLoads().

static GlobalVariable* OptimizeGlobalAddressOfMalloc ( GlobalVariable * GV,

MallocInst * MI

) [static]

OptimizeGlobalAddressOfMalloc - This function takes the specified global variable, and transforms the program as if it always contained the result of the specified malloc. Because it is always the result of the specified malloc, there is no reason to actually DO the malloc. Instead, turn the malloc into a global, and any laods of GV as uses of the new global.
Definition at line 633 of file GlobalOpt.cpp.
References ConstantPropUsersOf(), DEBUG, llvm::GlobalVariable::eraseFromParent(), llvm::Instruction::eraseFromParent(), False, llvm::AllocationInst::getAllocatedType(), llvm::AllocationInst::getArraySize(), llvm::SequentialType::getElementType(), llvm::Module::getGlobalList(), llvm::Value::getName(), llvm::BinaryOperator::getOpcode(), llvm::GlobalValue::getParent(), llvm::ConstantIntegral::getRawValue(), llvm::GlobalValue::getType(), llvm::Use::getUser(), llvm::Value::replaceAllUsesWith(), llvm::ISD::SetEQ, llvm::ISD::SetGE, llvm::ISD::SetGT, llvm::ISD::SetLE, llvm::ISD::SetLT, llvm::ISD::SetNE, True, llvm::Value::use_back(), llvm::Value::use_begin(), and llvm::Value::use_empty().
Referenced by OptimizeOnceStoredGlobal().

static bool OptimizeOnceStoredGlobal ( GlobalVariable * GV,

Value * StoredOnceVal,

Module::giterator & GVI,

TargetData & TD

) [static]

Definition at line 766 of file GlobalOpt.cpp.
References AllUsesOfLoadedValueWillTrapIfNull(), llvm::GlobalVariable::getInitializer(), llvm::Value::getType(), llvm::TargetData::getTypeSize(), llvm::Constant::isNullValue(), OptimizeAwayTrappingUsesOfLoads(), OptimizeGlobalAddressOfMalloc(), and ValueIsOnlyUsedLocallyOrStoredToOneGlobal().

static GlobalVariable* SRAGlobal ( GlobalVariable * GV ) [static]

SRAGlobal - Perform scalar replacement of aggregates on the specified global variable. This opens the door for other optimizations by exposing the behavior of the program in a more fine-grained way. We have determined that this transformation is safe already. We return the first global variable we insert so that the caller can reprocess it.
Definition at line 333 of file GlobalOpt.cpp.
References DEBUG, getAggregateConstantElement(), llvm::Module::getGlobalList(), llvm::GlobalVariable::getInitializer(), llvm::Value::getName(), llvm::User::getNumOperands(), llvm::User::getOperand(), llvm::GlobalValue::getParent(), llvm::Value::getType(), llvm::GlobalValue::hasInternalLinkage(), llvm::GlobalVariable::isConstant(), NumSRA, llvm::Value::replaceAllUsesWith(), llvm::Value::use_back(), llvm::Value::use_empty(), llvm::Value::use_size(), and llvm::utostr().

static Constant* TraverseGEPInitializer ( User * GEP,

Constant * Init

) [static]

Definition at line 254 of file GlobalOpt.cpp.
References getAggregateConstantElement(), llvm::User::getNumOperands(), and llvm::User::getOperand().
Referenced by CleanupConstantGlobalUsers().

static bool ValueIsOnlyUsedLocallyOrStoredToOneGlobal ( Instruction * V,

GlobalVariable * GV

) [static]

ValueIsOnlyUsedLocallyOrStoredToOneGlobal - Scan the use-list of V checking to make sure that there are no complex uses of V. We permit simple things like dereferencing the pointer, but not storing through the address, unless it is to the specified global.
Definition at line 745 of file GlobalOpt.cpp.
References E, llvm::User::getOperand(), llvm::Value::use_begin(), and llvm::Value::use_end().
Referenced by OptimizeOnceStoredGlobal().

Variable Documentation

Statistic NumDeleted("globalopt","Number of globals deleted") [static]

Referenced by llvm::Inliner::doFinalization(), InlineCallIfPossible(), OptimizeAwayTrappingUsesOfLoads(), and removeIdenticalCalls().

Statistic NumFnDeleted("globalopt","Number of functions deleted") [static]

Statistic NumGlobUses("globalopt","Number of global uses devirtualized") [static]

Referenced by OptimizeAwayTrappingUsesOfLoads().

Statistic NumMarked("globalopt","Number of globals marked constant") [static]

Statistic NumSRA("globalopt","Number of aggregate globals broken ""into scalars") [static]

Referenced by SRAGlobal().

Statistic NumSubstitute("globalopt","Number of globals with initializers stored into them") [static]

RegisterOpt<GlobalOpt> X("globalopt","Global Variable Optimizer") [static]


Classes
struct	GlobalStatus
Defines
#define	DEBUG_TYPE "globalopt"
Functions
ModulePass *	llvm::createGlobalOptimizerPass ()
static bool	ConstantIsDead (Constant *C)
static bool	AnalyzeGlobal (Value V, GlobalStatus &GS, std::set< PHINode > &PHIUsers)
static Constant *	getAggregateConstantElement (Constant Agg, Constant Idx)
static Constant *	TraverseGEPInitializer (User GEP, Constant Init)
static bool	CleanupConstantGlobalUsers (Value V, Constant Init)
static GlobalVariable *	SRAGlobal (GlobalVariable *GV)
static bool	AllUsesOfValueWillTrapIfNull (Value *V)
static bool	AllUsesOfLoadedValueWillTrapIfNull (GlobalVariable *GV)
static bool	OptimizeAwayTrappingUsesOfValue (Value V, Constant NewV)
static bool	OptimizeAwayTrappingUsesOfLoads (GlobalVariable GV, Constant LV)
static void	ConstantPropUsersOf (Value *V)
static GlobalVariable *	OptimizeGlobalAddressOfMalloc (GlobalVariable GV, MallocInst MI)
static bool	ValueIsOnlyUsedLocallyOrStoredToOneGlobal (Instruction V, GlobalVariable GV)
static bool	OptimizeOnceStoredGlobal (GlobalVariable GV, Value StoredOnceVal, Module::giterator &GVI, TargetData &TD)