GlobalOpt.cpp File Reference

#include "llvm/Transforms/IPO.h"
#include "llvm/CallingConv.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Instructions.h"
#include "llvm/IntrinsicInst.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Support/CallSite.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/STLExtras.h"
#include <algorithm>

Include dependency graph for GlobalOpt.cpp:

Go to the source code of this file.

Defines

#define DEBUG_TYPE "globalopt"

Functions

STATISTIC (NumMarked,"Number of globals marked constant")

STATISTIC (NumSRA,"Number of aggregate globals broken into scalars")

STATISTIC (NumHeapSRA,"Number of heap objects SRA'd")

STATISTIC (NumSubstitute,"Number of globals with initializers stored into them")

STATISTIC (NumDeleted,"Number of globals deleted")

STATISTIC (NumFnDeleted,"Number of functions deleted")

STATISTIC (NumGlobUses,"Number of global uses devirtualized")

STATISTIC (NumLocalized,"Number of globals localized")

STATISTIC (NumShrunkToBool,"Number of global vars shrunk to booleans")

STATISTIC (NumFastCallFns,"Number of functions converted to fastcc")

STATISTIC (NumCtorsEvaluated,"Number of static ctors evaluated")

STATISTIC (NumNestRemoved,"Number of nest attributes removed")

ModulePass * llvm::createGlobalOptimizerPass ()

static bool ConstantIsDead (Constant *C)

static bool AnalyzeGlobal (Value *V, GlobalStatus &GS, SmallPtrSet< PHINode *, 16 > &PHIUsers)

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

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

static bool isSafeSROAElementUse (Value *V)

static bool IsUserOfGlobalSafeForSRA (User *U, GlobalValue *GV)

static bool GlobalUsersSafeToSRA (GlobalValue *GV)

static GlobalVariable * SRAGlobal (GlobalVariable *GV, const TargetData &TD)

static bool AllUsesOfValueWillTrapIfNull (Value *V, SmallPtrSet< PHINode *, 8 > &PHIs)

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, SmallPtrSet< PHINode *, 8 > &PHIs)

static void ReplaceUsesOfMallocWithGlobal (Instruction *Alloc, GlobalVariable *GV)

static bool LoadUsesSimpleEnoughForHeapSRA (Value *V, SmallPtrSet< PHINode *, 32 > &LoadUsingPHIs)

static bool AllGlobalLoadUsesSimpleEnoughForHeapSRA (GlobalVariable *GV, MallocInst *MI)

static Value * GetHeapSROAValue (Value *V, unsigned FieldNo, DenseMap< Value *, std::vector< Value * > > &InsertedScalarizedValues, std::vector< std::pair< PHINode *, unsigned > > &PHIsToRewrite)

static void RewriteHeapSROALoadUser (Instruction *LoadUser, DenseMap< Value *, std::vector< Value * > > &InsertedScalarizedValues, std::vector< std::pair< PHINode *, unsigned > > &PHIsToRewrite)

static void RewriteUsesOfLoadForHeapSRoA (LoadInst *Load, DenseMap< Value *, std::vector< Value * > > &InsertedScalarizedValues, std::vector< std::pair< PHINode *, unsigned > > &PHIsToRewrite)

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

static bool TryToOptimizeStoreOfMallocToGlobal (GlobalVariable *GV, MallocInst *MI, Module::global_iterator &GVI, TargetData &TD)

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

static bool TryToShrinkGlobalToBoolean (GlobalVariable *GV, Constant *OtherVal)

static bool OnlyCalledDirectly (Function *F)

static void ChangeCalleesToFastCall (Function *F)

static AttrListPtr StripNest (const AttrListPtr &Attrs)

static void RemoveNestAttribute (Function *F)

static std::vector< Function * > ParseGlobalCtors (GlobalVariable *GV)

static GlobalVariable * InstallGlobalCtors (GlobalVariable *GCL, const std::vector< Function * > &Ctors)

static Constant * getVal (DenseMap< Value *, Constant * > &ComputedValues, Value *V)

static bool isSimpleEnoughPointerToCommit (Constant *C)

static Constant * EvaluateStoreInto (Constant *Init, Constant *Val, ConstantExpr *Addr, unsigned OpNo)

static void CommitValueTo (Constant *Val, Constant *Addr)

static Constant * ComputeLoadResult (Constant *P, const DenseMap< Constant *, Constant * > &Memory)

static bool EvaluateFunction (Function *F, Constant *&RetVal, const std::vector< Constant * > &ActualArgs, std::vector< Function * > &CallStack, DenseMap< Constant *, Constant * > &MutatedMemory, std::vector< GlobalVariable * > &AllocaTmps)

static bool EvaluateStaticConstructor (Function *F)

Variables

static RegisterPass< GlobalOpt > X ("globalopt","Global Variable Optimizer")

Define Documentation

#define DEBUG_TYPE "globalopt"

Definition at line 16 of file GlobalOpt.cpp.

Function Documentation

static bool AllGlobalLoadUsesSimpleEnoughForHeapSRA	(	GlobalVariable *	GV,
		MallocInst *	MI
	)			`[static]`

AllGlobalLoadUsesSimpleEnoughForHeapSRA - If all users of values loaded from GV are simple enough to perform HeapSRA, return true.

Definition at line 1066 of file GlobalOpt.cpp.

References llvm::SmallPtrSet< PtrType, SmallSize >::begin(), llvm::SmallPtrSet< PtrType, SmallSize >::count(), E, llvm::SmallPtrSet< PtrType, SmallSize >::end(), llvm::PHINode::getIncomingValue(), llvm::PHINode::getNumIncomingValues(), LI, LoadUsesSimpleEnoughForHeapSRA(), llvm::Value::use_begin(), and llvm::Value::use_end().

Referenced by TryToOptimizeStoreOfMallocToGlobal().

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 651 of file GlobalOpt.cpp.

References AllUsesOfValueWillTrapIfNull(), E, LI, llvm::Value::use_begin(), and llvm::Value::use_end().

Referenced by TryToOptimizeStoreOfMallocToGlobal().

static bool AllUsesOfValueWillTrapIfNull	(	Value *	V,
		SmallPtrSet< PHINode *, 8 > &	PHIs
	)			`[static]`

AllUsesOfValueWillTrapIfNull - Return true if all users of the specified value will trap if the value is dynamically null. PHIs keeps track of any phi nodes we've seen to avoid reprocessing them.

Definition at line 609 of file GlobalOpt.cpp.

References E, II, llvm::SmallPtrSet< PtrType, SmallSize >::insert(), llvm::Value::use_begin(), and llvm::Value::use_end().

Referenced by AllUsesOfLoadedValueWillTrapIfNull().

static bool AnalyzeGlobal	(	Value *	V,
		GlobalStatus &	GS,
		SmallPtrSet< PHINode *, 16 > &	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 157 of file GlobalOpt.cpp.

References llvm::CallingConv::C, ConstantIsDead(), E, F, llvm::Constant::getOperand(), GV, if(), llvm::SmallPtrSet< PtrType, SmallSize >::insert(), LI, llvm::Value::use_begin(), and llvm::Value::use_end().

static void ChangeCalleesToFastCall ( Function * F ) [static]

ChangeCalleesToFastCall - Walk all of the direct calls of the specified function, changing them to FastCC.

Definition at line 1777 of file GlobalOpt.cpp.

References E, Fast, llvm::CallSite::setCallingConv(), llvm::Value::use_begin(), llvm::Value::use_end(), and User.

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 281 of file GlobalOpt.cpp.

References BitCast, llvm::CallingConv::C, Changed, llvm::ConstantFoldInstruction(), llvm::ConstantFoldLoadThroughGEPConstantExpr(), ConstantIsDead(), E, llvm::MachineInstr::eraseFromParent(), llvm::ConstantExpr::getOpcode(), LI, MI, llvm::Value::use_begin(), and llvm::Value::use_end().

Referenced by OptimizeAwayTrappingUsesOfLoads().

static void CommitValueTo	(	Constant *	Val,
		Constant *	Addr
	)			`[static]`

CommitValueTo - We have decided that Addr (which satisfies the predicate isSimpleEnoughPointerToCommit) should get Val as its value. Make it happen.

Definition at line 2067 of file GlobalOpt.cpp.

References EvaluateStoreInto(), llvm::GlobalVariable::getInitializer(), llvm::Constant::getOperand(), llvm::GlobalVariable::hasInitializer(), and llvm::GlobalVariable::setInitializer().

Referenced by EvaluateStaticConstructor().

static Constant* ComputeLoadResult	(	Constant *	P,
		const DenseMap< Constant , Constant > &	Memory
	)			`[static]`

ComputeLoadResult - Return the value that would be computed by a load from P after the stores reflected by 'memory' have been performed. If we can't decide, return null.

Definition at line 2085 of file GlobalOpt.cpp.

References llvm::ConstantFoldLoadThroughGEPConstantExpr(), llvm::DenseMap< KeyT, ValueT, KeyInfoT, ValueInfoT >::end(), llvm::DenseMap< KeyT, ValueT, KeyInfoT, ValueInfoT >::find(), llvm::GlobalVariable::getInitializer(), llvm::GlobalVariable::hasInitializer(), and if().

Referenced by EvaluateFunction().

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 141 of file GlobalOpt.cpp.

References E, llvm::Value::use_begin(), and llvm::Value::use_end().

Referenced by AnalyzeGlobal(), CleanupConstantGlobalUsers(), and isSafeSROAElementUse().

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 789 of file GlobalOpt.cpp.

References llvm::ConstantFoldInstruction(), E, llvm::Value::use_begin(), and llvm::Value::use_end().

Referenced by OptimizeGlobalAddressOfMalloc().

static bool EvaluateFunction	(	Function *	F,
		Constant *&	RetVal,
		const std::vector< Constant * > &	ActualArgs,
		std::vector< Function * > &	CallStack,
		DenseMap< Constant , Constant > &	MutatedMemory,
		std::vector< GlobalVariable * > &	AllocaTmps
	)			`[static]`

EvaluateFunction - Evaluate a call to function F, returning true if successful, false if we can't evaluate it. ActualArgs contains the formal arguments for the function.

Values - As we compute SSA register values, we store their contents here.

ExecutedBlocks - We only handle non-looping, non-recursive code. As such, we can only evaluate any one basic block at most once. This set keeps track of what we have executed so we can detect recursive cases etc.

Definition at line 2114 of file GlobalOpt.cpp.

References AI, llvm::Function::arg_begin(), llvm::Function::arg_end(), llvm::BasicBlock::begin(), llvm::Function::begin(), llvm::CallingConv::C, ComputeLoadResult(), llvm::ConstantFoldCall(), llvm::dyn_cast(), E, llvm::SequentialType::getElementType(), llvm::Function::getFunctionType(), llvm::PHINode::getIncomingValueForBlock(), llvm::Value::getName(), llvm::AllocationInst::getType(), llvm::Value::getType(), getVal(), llvm::ConstantInt::getZExtValue(), llvm::SmallPtrSet< PtrType, SmallSize >::insert(), llvm::AllocationInst::isArrayAllocation(), llvm::Function::isDeclaration(), isSimpleEnoughPointerToCommit(), llvm::FunctionType::isVarArg(), LI, llvm::Function::size(), Ty, Val, and Values.

Referenced by EvaluateStaticConstructor().

static bool EvaluateStaticConstructor ( Function * F ) [static]

EvaluateStaticConstructor - Evaluate static constructors in the function, if we can. Return true if we can, false otherwise.

MutatedMemory - For each store we execute, we update this map. Loads check this to get the most up-to-date value. If evaluation is successful, this state is committed to the process.

AllocaTmps - To 'execute' an alloca, we create a temporary global variable to represent its body. This vector is needed so we can delete the temporary globals when we are done.

CallStack - This is used to detect recursion. In pathological situations we could hit exponential behavior, but at least there is nothing unbounded.

Definition at line 2284 of file GlobalOpt.cpp.

References llvm::DenseMap< KeyT, ValueT, KeyInfoT, ValueInfoT >::begin(), CommitValueTo(), DOUT, E, llvm::DenseMap< KeyT, ValueT, KeyInfoT, ValueInfoT >::end(), EvaluateFunction(), llvm::Value::getName(), llvm::GlobalValue::getType(), llvm::Value::replaceAllUsesWith(), llvm::DenseMap< KeyT, ValueT, KeyInfoT, ValueInfoT >::size(), and llvm::Value::use_empty().

static Constant* EvaluateStoreInto	(	Constant *	Init,
		Constant *	Val,
		ConstantExpr *	Addr,
		unsigned	OpNo
	)			`[static]`

EvaluateStoreInto - Evaluate a piece of a constantexpr store into a global initializer. This returns 'Init' modified to reflect 'Val' stored into it. At this point, the GEP operands of Addr [0, OpNo) have been stepped into.

Definition at line 2004 of file GlobalOpt.cpp.

References llvm::StructType::getElementType(), llvm::StructType::getNumElements(), llvm::User::getNumOperands(), llvm::Constant::getOperand(), llvm::Value::getType(), llvm::ConstantInt::getZExtValue(), Idx, llvm::StructType::isPacked(), llvm::User::op_begin(), and llvm::User::op_end().

Referenced by CommitValueTo().

static Constant* getAggregateConstantElement	(	Constant *	Agg,
		Constant *	Idx
	)			`[static]`

Definition at line 245 of file GlobalOpt.cpp.

References CA, CP, llvm::dyn_cast(), llvm::UndefValue::get(), llvm::Constant::getNullValue(), llvm::Constant::getOperand(), llvm::Value::getType(), and llvm::ConstantInt::getZExtValue().

Referenced by SRAGlobal().

static Value* GetHeapSROAValue	(	Value *	V,
		unsigned	FieldNo,
		DenseMap< Value , std::vector< Value > > &	InsertedScalarizedValues,
		std::vector< std::pair< PHINode *, unsigned > > &	PHIsToRewrite
	)			`[static]`

Definition at line 1111 of file GlobalOpt.cpp.

References llvm::PHINode::Create(), llvm::StructType::getElementType(), llvm::PointerType::getUnqual(), LI, and llvm::utostr().

Referenced by PerformHeapAllocSRoA(), and RewriteHeapSROALoadUser().

static Constant* getVal	(	DenseMap< Value , Constant > &	ComputedValues,
		Value *	V
	)			`[static]`

Definition at line 1970 of file GlobalOpt.cpp.

References R.

Referenced by EvaluateFunction().

static bool GlobalUsersSafeToSRA ( GlobalValue * GV ) [static]

GlobalUsersSafeToSRA - Look at all uses of the global and decide whether it is safe for us to perform this transformation.

Definition at line 447 of file GlobalOpt.cpp.

References E, IsUserOfGlobalSafeForSRA(), llvm::Value::use_begin(), and llvm::Value::use_end().

Referenced by SRAGlobal().

static GlobalVariable* InstallGlobalCtors	(	GlobalVariable *	GCL,
		const std::vector< Function * > &	Ctors
	)			`[static]`

InstallGlobalCtors - Given a specified llvm.global_ctors list, install the specified array, returning the new global to use.

Definition at line 1912 of file GlobalOpt.cpp.

References llvm::GlobalVariable::eraseFromParent(), llvm::SequentialType::getElementType(), llvm::Module::getGlobalList(), llvm::GlobalVariable::getInitializer(), llvm::GlobalValue::getLinkage(), llvm::GlobalValue::getParent(), llvm::Value::getType(), llvm::GlobalValue::getType(), llvm::GlobalVariable::isConstant(), llvm::GlobalVariable::isThreadLocal(), llvm::Value::replaceAllUsesWith(), llvm::GlobalVariable::setInitializer(), llvm::Value::takeName(), llvm::Value::use_empty(), and V.

static bool isSafeSROAElementUse ( Value * V ) [static]

isSafeSROAElementUse - Return true if the specified instruction is a safe user of a derived expression from a global that we want to SROA.

Definition at line 352 of file GlobalOpt.cpp.

References llvm::CallingConv::C, ConstantIsDead(), llvm::dyn_cast(), E, llvm::User::getNumOperands(), llvm::User::getOperand(), llvm::Value::use_begin(), and llvm::Value::use_end().

Referenced by IsUserOfGlobalSafeForSRA().

static bool isSimpleEnoughPointerToCommit ( Constant * C ) [static]

isSimpleEnoughPointerToCommit - Return true if this constant is simple enough for us to understand. In particular, if it is a cast of something, we punt. We basically just support direct accesses to globals and GEP's of globals. This should be kept up to date with CommitValueTo.

Definition at line 1982 of file GlobalOpt.cpp.

References llvm::ConstantFoldLoadThroughGEPConstantExpr(), llvm::GlobalVariable::getInitializer(), llvm::GlobalValue::hasExternalLinkage(), llvm::GlobalVariable::hasInitializer(), llvm::GlobalValue::hasLocalLinkage(), and llvm::GlobalVariable::isDeclaration().

Referenced by EvaluateFunction().

static bool IsUserOfGlobalSafeForSRA	(	User *	U,
		GlobalValue *	GV
	)			`[static]`

IsUserOfGlobalSafeForSRA - U is a direct user of the specified global value. Look at it and its uses and decide whether it is safe to SROA this global.

Definition at line 386 of file GlobalOpt.cpp.

References llvm::dyn_cast(), E, llvm::gep_type_begin(), llvm::gep_type_end(), llvm::User::getNumOperands(), getOpcode(), llvm::generic_gep_type_iterator< ItTy >::getOperand(), llvm::User::getOperand(), llvm::ConstantInt::getZExtValue(), Idx, isSafeSROAElementUse(), llvm::Value::use_begin(), and llvm::Value::use_end().

Referenced by GlobalUsersSafeToSRA().

static bool LoadUsesSimpleEnoughForHeapSRA	(	Value *	V,
		SmallPtrSet< PHINode *, 32 > &	LoadUsingPHIs
	)			`[static]`

LoadUsesSimpleEnoughForHeapSRA - Verify that all uses of V (a load, or a phi of a load) are simple enough to perform heap SRA on. This permits GEP's that index through the array and struct field, icmps of null, and PHIs.

Definition at line 1020 of file GlobalOpt.cpp.

References E, llvm::SmallPtrSet< PtrType, SmallSize >::insert(), llvm::Value::use_begin(), and llvm::Value::use_end().

Referenced by AllGlobalLoadUsesSimpleEnoughForHeapSRA().

static bool OnlyCalledDirectly ( Function * F ) [static]

OnlyCalledDirectly - Return true if the specified function is only called directly. In other words, its address is never taken.

Definition at line 1761 of file GlobalOpt.cpp.

References llvm::dyn_cast(), E, llvm::User::op_begin(), llvm::User::op_end(), llvm::Value::use_begin(), and llvm::Value::use_end().

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 735 of file GlobalOpt.cpp.

References Changed, CleanupConstantGlobalUsers(), DOUT, E, llvm::GlobalVariable::eraseFromParent(), llvm::User::getOperand(), LI, 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 668 of file GlobalOpt.cpp.

References llvm::CallingConv::C, Changed, E, llvm::ConstantExpr::getCast(), llvm::ConstantExpr::getGetElementPtr(), llvm::User::getNumOperands(), llvm::User::getOperand(), llvm::Value::getType(), LI, llvm::SmallVectorImpl< T >::push_back(), llvm::SmallVectorImpl< T >::reserve(), llvm::User::setOperand(), llvm::SmallVectorImpl< T >::size(), 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 loads of GV as uses of the new global.

Definition at line 808 of file GlobalOpt.cpp.

References ConstantPropUsersOf(), llvm::GetElementPtrInst::Create(), llvm::BinaryOperator::CreateNot(), DOUT, llvm::GlobalVariable::eraseFromParent(), llvm::Instruction::eraseFromParent(), llvm::UndefValue::get(), llvm::ArrayType::get(), llvm::ConstantExpr::getBitCast(), llvm::SequentialType::getElementType(), llvm::ConstantInt::getFalse(), llvm::Module::getGlobalList(), llvm::Value::getName(), llvm::Constant::getNullValue(), llvm::GlobalValue::getParent(), llvm::CmpInst::getPredicate(), llvm::ConstantInt::getTrue(), llvm::GlobalValue::getType(), llvm::Use::getUser(), llvm::ConstantInt::getZExtValue(), llvm::CmpInst::ICMP_EQ, llvm::CmpInst::ICMP_NE, llvm::CmpInst::ICMP_SGE, llvm::CmpInst::ICMP_SGT, llvm::CmpInst::ICMP_SLE, llvm::CmpInst::ICMP_SLT, llvm::CmpInst::ICMP_UGE, llvm::CmpInst::ICMP_UGT, llvm::CmpInst::ICMP_ULE, llvm::CmpInst::ICMP_ULT, Indices, llvm::Type::Int1Ty, llvm::Type::Int32Ty, llvm::GlobalValue::InternalLinkage, llvm::GlobalVariable::isThreadLocal(), LI, LV, llvm::Value::replaceAllUsesWith(), llvm::Value::use_back(), and llvm::Value::use_empty().

Referenced by TryToOptimizeStoreOfMallocToGlobal().

static bool OptimizeOnceStoredGlobal	(	GlobalVariable *	GV,
		Value *	StoredOnceVal,
		Module::global_iterator &	GVI,
		TargetData &	TD
	)			`[static]`

Definition at line 1496 of file GlobalOpt.cpp.

References llvm::ConstantExpr::getBitCast(), llvm::GlobalVariable::getInitializer(), llvm::Value::getType(), llvm::Constant::isNullValue(), MI, OptimizeAwayTrappingUsesOfLoads(), llvm::Value::stripPointerCasts(), and TryToOptimizeStoreOfMallocToGlobal().

static std::vector<Function*> ParseGlobalCtors ( GlobalVariable * GV ) [static]

ParseGlobalCtors - Given a llvm.global_ctors list that we can understand, return a list of the functions and null terminator as a vector.

Definition at line 1899 of file GlobalOpt.cpp.

References llvm::GlobalVariable::getInitializer(), llvm::User::getNumOperands(), llvm::Constant::getOperand(), llvm::User::op_begin(), and llvm::User::op_end().

static GlobalVariable* PerformHeapAllocSRoA	(	GlobalVariable *	GV,
		MallocInst *	MI
	)			`[static]`

PerformHeapAllocSRoA - MI is an allocation of an array of structures. Break it up into multiple allocations of arrays of the fields.

InsertedScalarizedLoads - As we process loads, if we can't immediately update all uses of the load, keep track of what scalarized loads are inserted for a given load.

Definition at line 1236 of file GlobalOpt.cpp.

References llvm::PHINode::addIncoming(), llvm::DenseMap< KeyT, ValueT, KeyInfoT, ValueInfoT >::begin(), llvm::BranchInst::Create(), llvm::BasicBlock::Create(), DOUT, E, llvm::DenseMap< KeyT, ValueT, KeyInfoT, ValueInfoT >::end(), llvm::GlobalVariable::eraseFromParent(), llvm::Instruction::eraseFromParent(), llvm::SequentialType::getElementType(), llvm::StructType::getElementType(), GetHeapSROAValue(), llvm::PHINode::getIncomingBlock(), llvm::PHINode::getIncomingValue(), llvm::Value::getName(), llvm::Constant::getNullValue(), llvm::StructType::getNumElements(), llvm::PHINode::getNumIncomingValues(), llvm::User::getOperand(), llvm::BasicBlock::getParent(), llvm::BasicBlock::getTerminator(), llvm::Value::getType(), llvm::Intrinsic::getType(), llvm::PointerType::getUnqual(), llvm::CmpInst::ICMP_EQ, llvm::CmpInst::ICMP_NE, llvm::GlobalValue::InternalLinkage, llvm::GlobalVariable::isThreadLocal(), LI, ReplaceUsesOfMallocWithGlobal(), RewriteUsesOfLoadForHeapSRoA(), llvm::BasicBlock::splitBasicBlock(), llvm::Value::use_begin(), llvm::Value::use_end(), and llvm::utostr().

Referenced by TryToOptimizeStoreOfMallocToGlobal().

static void RemoveNestAttribute ( Function * F ) [static]

Definition at line 1796 of file GlobalOpt.cpp.

References E, llvm::CallSite::getAttributes(), llvm::Function::getAttributes(), llvm::CallSite::setAttributes(), llvm::Function::setAttributes(), StripNest(), llvm::Value::use_begin(), llvm::Value::use_end(), and User.

static void ReplaceUsesOfMallocWithGlobal	(	Instruction *	Alloc,
		GlobalVariable *	GV
	)			`[static]`

ReplaceUsesOfMallocWithGlobal - The Alloc pointer is stored into GV somewhere. Transform all uses of the allocation into loads from the global and uses of the resultant pointer. Further, delete the store into GV. This assumes that these value pass the 'ValueIsOnlyUsedLocallyOrStoredToOneGlobal' predicate.

Definition at line 977 of file GlobalOpt.cpp.

References llvm::Instruction::eraseFromParent(), llvm::Value::getName(), llvm::User::replaceUsesOfWith(), llvm::Value::use_begin(), and llvm::Value::use_empty().

Referenced by PerformHeapAllocSRoA().

static void RewriteHeapSROALoadUser	(	Instruction *	LoadUser,
		DenseMap< Value , std::vector< Value > > &	InsertedScalarizedValues,
		std::vector< std::pair< PHINode *, unsigned > > &	PHIsToRewrite
	)			`[static]`

RewriteHeapSROALoadUser - Given a load instruction and a value derived from the load, rewrite the derived value to use the HeapSRoA'd load.

Definition at line 1152 of file GlobalOpt.cpp.

References llvm::GetElementPtrInst::Create(), E, GetHeapSROAValue(), llvm::Value::getName(), llvm::Constant::getNullValue(), llvm::Value::getType(), InsertPos, llvm::Value::replaceAllUsesWith(), llvm::tie(), llvm::Value::use_begin(), and llvm::Value::use_end().

Referenced by RewriteUsesOfLoadForHeapSRoA().

static void RewriteUsesOfLoadForHeapSRoA	(	LoadInst *	Load,
		DenseMap< Value , std::vector< Value > > &	InsertedScalarizedValues,
		std::vector< std::pair< PHINode *, unsigned > > &	PHIsToRewrite
	)			`[static]`

RewriteUsesOfLoadForHeapSRoA - We are performing Heap SRoA on a global. Ptr is a value loaded from the global. Eliminate all uses of Ptr, making them use FieldGlobals instead. All uses of loaded values satisfy AllGlobalLoadUsesSimpleEnoughForHeapSRA.

Definition at line 1219 of file GlobalOpt.cpp.

References E, llvm::Instruction::eraseFromParent(), RewriteHeapSROALoadUser(), llvm::Value::use_begin(), llvm::Value::use_empty(), and llvm::Value::use_end().

Referenced by PerformHeapAllocSRoA().

static GlobalVariable* SRAGlobal	(	GlobalVariable *	GV,
		const TargetData &	TD
	)			`[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 462 of file GlobalOpt.cpp.

References llvm::GetElementPtrInst::Create(), DOUT, llvm::ConstantInt::get(), llvm::TargetData::getABITypeAlignment(), llvm::PointerType::getAddressSpace(), getAggregateConstantElement(), llvm::GlobalValue::getAlignment(), llvm::StructLayout::getElementOffset(), llvm::ConstantExpr::getGetElementPtr(), llvm::Module::getGlobalList(), llvm::GlobalVariable::getInitializer(), llvm::Value::getName(), llvm::Constant::getNullValue(), llvm::User::getNumOperands(), getOpcode(), llvm::User::getOperand(), llvm::GlobalValue::getParent(), llvm::TargetData::getStructLayout(), llvm::GlobalValue::getType(), llvm::TargetData::getTypePaddedSize(), GlobalUsersSafeToSRA(), llvm::GlobalValue::hasLocalLinkage(), llvm::Value::hasNUsesOrMore(), llvm::Type::Int32Ty, llvm::GlobalValue::InternalLinkage, llvm::GlobalVariable::isConstant(), llvm::GlobalVariable::isThreadLocal(), llvm::MinAlign(), llvm::SmallVectorImpl< T >::push_back(), llvm::Value::replaceAllUsesWith(), llvm::GlobalValue::setAlignment(), llvm::SmallVectorImpl< T >::size(), Ty, llvm::utostr(), and Val.

STATISTIC	(	NumNestRemoved	,
		"Number of nest attributes removed"
	)

STATISTIC	(	NumCtorsEvaluated	,
		"Number of static ctors evaluated"
	)

STATISTIC	(	NumFastCallFns	,
		"Number of functions converted to fastcc"
	)

STATISTIC	(	NumShrunkToBool	,
		"Number of global vars shrunk to booleans"
	)

STATISTIC	(	NumLocalized	,
		"Number of globals localized"
	)

STATISTIC	(	NumGlobUses	,
		"Number of global uses devirtualized"
	)

STATISTIC	(	NumFnDeleted	,
		"Number of functions deleted"
	)

STATISTIC	(	NumDeleted	,
		"Number of globals deleted"
	)

STATISTIC	(	NumSubstitute	,
		"Number of globals with initializers stored into them"
	)

STATISTIC	(	NumHeapSRA	,
		"Number of heap objects SRA'd"
	)

STATISTIC	(	NumSRA	,
		"Number of aggregate globals broken into scalars"
	)

STATISTIC	(	NumMarked	,
		"Number of globals marked constant"
	)

static AttrListPtr StripNest ( const AttrListPtr & Attrs ) [static]

Definition at line 1784 of file GlobalOpt.cpp.

References llvm::AttributeWithIndex::Attrs, llvm::AttrListPtr::getNumSlots(), llvm::AttrListPtr::getSlot(), llvm::AttributeWithIndex::Index, llvm::Attribute::Nest, and llvm::AttrListPtr::removeAttr().

Referenced by RemoveNestAttribute().

static bool TryToOptimizeStoreOfMallocToGlobal	(	GlobalVariable *	GV,
		MallocInst *	MI,
		Module::global_iterator &	GVI,
		TargetData &	TD
	)			`[static]`

TryToOptimizeStoreOfMallocToGlobal - This function is called when we see a pointer global variable with a single value stored it that is a malloc or cast of malloc.

Definition at line 1411 of file GlobalOpt.cpp.

References AllGlobalLoadUsesSimpleEnoughForHeapSRA(), AllUsesOfLoadedValueWillTrapIfNull(), llvm::Instruction::eraseFromParent(), llvm::ConstantInt::get(), llvm::AllocationInst::getAllocatedType(), llvm::AllocationInst::getArraySize(), llvm::AllocationInst::getType(), llvm::TargetData::getTypePaddedSize(), llvm::Type::Int32Ty, llvm::AllocationInst::isArrayAllocation(), llvm::Type::isSized(), OptimizeGlobalAddressOfMalloc(), PerformHeapAllocSRoA(), llvm::Value::replaceAllUsesWith(), llvm::Value::takeName(), and ValueIsOnlyUsedLocallyOrStoredToOneGlobal().

Referenced by OptimizeOnceStoredGlobal().

static bool TryToShrinkGlobalToBoolean	(	GlobalVariable *	GV,
		Constant *	OtherVal
	)			`[static]`

TryToShrinkGlobalToBoolean - At this point, we have learned that the only two values ever stored into GV are its initializer and OtherVal. See if we can shrink the global into a boolean and select between the two values whenever it is used. This exposes the values to other scalar optimizations.

Definition at line 1528 of file GlobalOpt.cpp.

References llvm::SelectInst::Create(), DOUT, E, llvm::Instruction::eraseFromParent(), llvm::ConstantInt::get(), llvm::SequentialType::getElementType(), llvm::ConstantInt::getFalse(), llvm::Module::getGlobalList(), llvm::Value::getName(), llvm::User::getOperand(), llvm::GlobalValue::getParent(), llvm::Value::getType(), llvm::GlobalValue::getType(), llvm::Type::Int1Ty, llvm::GlobalValue::InternalLinkage, llvm::Type::isFloatingPoint(), llvm::Constant::isNullValue(), LI, llvm::Value::replaceAllUsesWith(), llvm::Value::takeName(), llvm::Value::use_begin(), and llvm::Value::use_end().

static bool ValueIsOnlyUsedLocallyOrStoredToOneGlobal	(	Instruction *	V,
		GlobalVariable *	GV,
		SmallPtrSet< PHINode *, 8 > &	PHIs
	)			`[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 929 of file GlobalOpt.cpp.

References llvm::dyn_cast(), E, llvm::User::getOperand(), llvm::SmallPtrSet< PtrType, SmallSize >::insert(), Inst, llvm::Value::use_begin(), and llvm::Value::use_end().

Referenced by TryToOptimizeStoreOfMallocToGlobal().

Variable Documentation

Function* AccessingFunction

AccessingFunction/HasMultipleAccessingFunctions - These start out null/false. When the first accessing function is noticed, it is recorded. When a second different accessing function is noticed, HasMultipleAccessingFunctions is set to true.

Definition at line 120 of file GlobalOpt.cpp.

bool HasMultipleAccessingFunctions

Definition at line 121 of file GlobalOpt.cpp.

bool HasNonInstructionUser

HasNonInstructionUser - Set to true if this global has a user that is not an instruction (e.g. a constant expr or GV initializer).

Definition at line 125 of file GlobalOpt.cpp.

bool HasPHIUser

HasPHIUser - Set to true if this global has a user that is a PHI node.

Definition at line 128 of file GlobalOpt.cpp.

char ID [static]

Definition at line 59 of file GlobalOpt.cpp.

bool isLoaded

isLoaded - True if the global is ever loaded. If the global isn't ever loaded it can be deleted.

Definition at line 87 of file GlobalOpt.cpp.

Value* StoredOnceValue

StoredOnceValue - If only one value (besides the initializer constant) is ever stored to this global, keep track of what value it is.

Definition at line 114 of file GlobalOpt.cpp.

enum { ... } GlobalStatus::StoredType StoredType

StoredType - Keep track of what stores to the global look like.

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


Defines
#define	DEBUG_TYPE "globalopt"
Functions
	STATISTIC (NumMarked,"Number of globals marked constant")
	STATISTIC (NumSRA,"Number of aggregate globals broken into scalars")
	STATISTIC (NumHeapSRA,"Number of heap objects SRA'd")
	STATISTIC (NumSubstitute,"Number of globals with initializers stored into them")
	STATISTIC (NumDeleted,"Number of globals deleted")
	STATISTIC (NumFnDeleted,"Number of functions deleted")
	STATISTIC (NumGlobUses,"Number of global uses devirtualized")
	STATISTIC (NumLocalized,"Number of globals localized")
	STATISTIC (NumShrunkToBool,"Number of global vars shrunk to booleans")
	STATISTIC (NumFastCallFns,"Number of functions converted to fastcc")
	STATISTIC (NumCtorsEvaluated,"Number of static ctors evaluated")
	STATISTIC (NumNestRemoved,"Number of nest attributes removed")
ModulePass *	llvm::createGlobalOptimizerPass ()
static bool	ConstantIsDead (Constant *C)
static bool	AnalyzeGlobal (Value V, GlobalStatus &GS, SmallPtrSet< PHINode , 16 > &PHIUsers)
static Constant *	getAggregateConstantElement (Constant Agg, Constant Idx)
static bool	CleanupConstantGlobalUsers (Value V, Constant Init)
static bool	isSafeSROAElementUse (Value *V)
static bool	IsUserOfGlobalSafeForSRA (User U, GlobalValue GV)
static bool	GlobalUsersSafeToSRA (GlobalValue *GV)
static GlobalVariable *	SRAGlobal (GlobalVariable *GV, const TargetData &TD)
static bool	AllUsesOfValueWillTrapIfNull (Value V, SmallPtrSet< PHINode , 8 > &PHIs)
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, SmallPtrSet< PHINode *, 8 > &PHIs)
static void	ReplaceUsesOfMallocWithGlobal (Instruction Alloc, GlobalVariable GV)
static bool	LoadUsesSimpleEnoughForHeapSRA (Value V, SmallPtrSet< PHINode , 32 > &LoadUsingPHIs)
static bool	AllGlobalLoadUsesSimpleEnoughForHeapSRA (GlobalVariable GV, MallocInst MI)
static Value *	GetHeapSROAValue (Value V, unsigned FieldNo, DenseMap< Value , std::vector< Value * > > &InsertedScalarizedValues, std::vector< std::pair< PHINode *, unsigned > > &PHIsToRewrite)
static void	RewriteHeapSROALoadUser (Instruction LoadUser, DenseMap< Value , std::vector< Value * > > &InsertedScalarizedValues, std::vector< std::pair< PHINode *, unsigned > > &PHIsToRewrite)
static void	RewriteUsesOfLoadForHeapSRoA (LoadInst Load, DenseMap< Value , std::vector< Value * > > &InsertedScalarizedValues, std::vector< std::pair< PHINode *, unsigned > > &PHIsToRewrite)
static GlobalVariable *	PerformHeapAllocSRoA (GlobalVariable GV, MallocInst MI)
static bool	TryToOptimizeStoreOfMallocToGlobal (GlobalVariable GV, MallocInst MI, Module::global_iterator &GVI, TargetData &TD)
static bool	OptimizeOnceStoredGlobal (GlobalVariable GV, Value StoredOnceVal, Module::global_iterator &GVI, TargetData &TD)
static bool	TryToShrinkGlobalToBoolean (GlobalVariable GV, Constant OtherVal)
static bool	OnlyCalledDirectly (Function *F)
static void	ChangeCalleesToFastCall (Function *F)
static AttrListPtr	StripNest (const AttrListPtr &Attrs)
static void	RemoveNestAttribute (Function *F)
static std::vector< Function * >	ParseGlobalCtors (GlobalVariable *GV)
static GlobalVariable *	InstallGlobalCtors (GlobalVariable GCL, const std::vector< Function > &Ctors)
static Constant *	getVal (DenseMap< Value , Constant > &ComputedValues, Value *V)
static bool	isSimpleEnoughPointerToCommit (Constant *C)
static Constant *	EvaluateStoreInto (Constant Init, Constant Val, ConstantExpr *Addr, unsigned OpNo)
static void	CommitValueTo (Constant Val, Constant Addr)
static Constant *	ComputeLoadResult (Constant P, const DenseMap< Constant , Constant * > &Memory)
static bool	EvaluateFunction (Function F, Constant &RetVal, const std::vector< Constant * > &ActualArgs, std::vector< Function * > &CallStack, DenseMap< Constant , Constant > &MutatedMemory, std::vector< GlobalVariable * > &AllocaTmps)
static bool	EvaluateStaticConstructor (Function *F)
Variables
static RegisterPass< GlobalOpt >	X ("globalopt","Global Variable Optimizer")