Helper class for SSA formation on a set of values defined in multiple blocks. More...

#include <SSAUpdater.h>

Public Member Functions
	SSAUpdater (SmallVectorImpl< PHINode * > *InsertedPHIs=nullptr)
	~SSAUpdater ()
void	Initialize (Type *Ty, StringRef Name)
	Reset this object to get ready for a new set of SSA updates with type 'Ty'.
void	AddAvailableValue (BasicBlock BB, Value V)
	Indicate that a rewritten value is available in the specified block with the specified value.
bool	HasValueForBlock (BasicBlock *BB) const
	Return true if the SSAUpdater already has a value for the specified block.
Value *	GetValueAtEndOfBlock (BasicBlock *BB)
	Construct SSA form, materializing a value that is live at the end of the specified block.
Value *	GetValueInMiddleOfBlock (BasicBlock *BB)
	Construct SSA form, materializing a value that is live in the middle of the specified block.
void	RewriteUse (Use &U)
	Rewrite a use of the symbolic value.
void	RewriteUseAfterInsertions (Use &U)
	Rewrite a use like `RewriteUse` but handling in-block definitions.
Friends
class	SSAUpdaterTraits< SSAUpdater >

Detailed Description

Helper class for SSA formation on a set of values defined in multiple blocks.

This is used when code duplication or another unstructured transformation wants to rewrite a set of uses of one value with uses of a set of values.

Definition at line 37 of file SSAUpdater.h.

Constructor & Destructor Documentation

SSAUpdater::SSAUpdater ( SmallVectorImpl< PHINode * > * InsertedPHIs = nullptr ) [explicit]

If InsertedPHIs is specified, it will be filled in with all PHI Nodes created by rewriting.

Definition at line 37 of file SSAUpdater.cpp.

SSAUpdater::~SSAUpdater ( )

Definition at line 40 of file SSAUpdater.cpp.

Member Function Documentation

void SSAUpdater::AddAvailableValue	(	BasicBlock *	BB,
		Value *	V
	)

Indicate that a rewritten value is available in the specified block with the specified value.

Definition at line 57 of file SSAUpdater.cpp.

References getAvailableVals(), and llvm::Value::getType().

Referenced by ConstructSSAForLoadSet(), processInstruction(), RewriteUsesOfClonedInstructions(), and llvm::LoadAndStorePromoter::run().

Value * SSAUpdater::GetValueAtEndOfBlock ( BasicBlock * BB )

Construct SSA form, materializing a value that is live at the end of the specified block.

Definition at line 80 of file SSAUpdater.cpp.

Referenced by GetValueInMiddleOfBlock(), RewriteUse(), and RewriteUseAfterInsertions().

Value * SSAUpdater::GetValueInMiddleOfBlock ( BasicBlock * BB )

Construct SSA form, materializing a value that is live in the middle of the specified block.

GetValueInMiddleOfBlock is the same as GetValueAtEndOfBlock except in one important case: if there is a definition of the rewritten value after the 'use' in BB. Consider code like this:

      X1 = ...
   SomeBB:
      use(X)
      X2 = ...
      br Cond, SomeBB, OutBB

In this case, there are two values (X1 and X2) added to the AvailableVals set by the client of the rewriter, and those values are both live out of their respective blocks. However, the use of X happens in the *middle* of a block. Because of this, we need to insert a new PHI node in SomeBB to merge the appropriate values, and this value isn't live out of the block.

Definition at line 85 of file SSAUpdater.cpp.

References llvm::PHINode::addIncoming(), llvm::SmallVectorTemplateCommon< T >::begin(), llvm::BasicBlock::begin(), llvm::PHINode::Create(), llvm::dbgs(), DEBUG, llvm::dyn_cast(), llvm::SmallVectorBase::empty(), llvm::SmallVectorTemplateCommon< T >::end(), llvm::Instruction::eraseFromParent(), llvm::BasicBlock::front(), llvm::UndefValue::get(), llvm::BasicBlock::getFirstNonPHI(), GetValueAtEndOfBlock(), HasValueForBlock(), I, IsEquivalentPHI(), llvm::pred_begin(), llvm::pred_end(), llvm::SmallVectorTemplateBase< T, isPodLike< T >::value >::push_back(), llvm::SmallVectorTemplateBase< T, isPodLike >::push_back(), llvm::Instruction::setDebugLoc(), llvm::SimplifyInstruction(), and llvm::SmallVectorTemplateCommon< T >::size().

Referenced by ConstructSSAForLoadSet(), RewriteUse(), and llvm::LoadAndStorePromoter::run().

bool SSAUpdater::HasValueForBlock ( BasicBlock * BB ) const

Return true if the SSAUpdater already has a value for the specified block.

Definition at line 53 of file SSAUpdater.cpp.

References llvm::DenseMapBase< DerivedT, KeyT, ValueT, KeyInfoT >::count(), and getAvailableVals().

Referenced by ConstructSSAForLoadSet(), GetValueInMiddleOfBlock(), and processInstruction().

void SSAUpdater::Initialize	(	Type *	Ty,
		StringRef	Name
	)

Reset this object to get ready for a new set of SSA updates with type 'Ty'.

PHI nodes get a name based on 'Name'.

Definition at line 44 of file SSAUpdater.cpp.

References llvm::DenseMapBase< DerivedT, KeyT, ValueT, KeyInfoT >::clear(), getAvailableVals(), and Name.

Referenced by ConstructSSAForLoadSet(), llvm::LoadAndStorePromoter::LoadAndStorePromoter(), processInstruction(), and RewriteUsesOfClonedInstructions().

void SSAUpdater::RewriteUse ( Use & U )

Rewrite a use of the symbolic value.

This handles PHI nodes, which use their value in the corresponding predecessor. Note that this will not work if the use is supposed to be rewritten to a value defined in the same block as the use, but above it. Any 'AddAvailableValue's added for the use's block will be considered to be below it.

Definition at line 176 of file SSAUpdater.cpp.

References llvm::Use::get(), llvm::Instruction::getParent(), llvm::Use::getUser(), GetValueAtEndOfBlock(), GetValueInMiddleOfBlock(), llvm::Use::set(), and llvm::ValueHandleBase::ValueIsRAUWd().

Referenced by processInstruction(), and RewriteUsesOfClonedInstructions().

void SSAUpdater::RewriteUseAfterInsertions ( Use & U )

Rewrite a use like RewriteUse but handling in-block definitions.

This version of the method can rewrite uses in the same block as a definition, because it assumes that all uses of a value are below any inserted values.

Definition at line 193 of file SSAUpdater.cpp.

References llvm::Instruction::getParent(), llvm::Use::getUser(), GetValueAtEndOfBlock(), and llvm::Use::set().

Friends And Related Function Documentation

friend class SSAUpdaterTraits< SSAUpdater > [friend]

Definition at line 38 of file SSAUpdater.h.

The documentation for this class was generated from the following files:

Public Member Functions

Friends

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Friends And Related Function Documentation