Captures loop safety information. More...

#include "llvm/Analysis/MustExecute.h"

Inheritance diagram for llvm::LoopSafetyInfo:

Public Member Functions
const DenseMap< BasicBlock *, ColorVector > &	getBlockColors () const
	Returns block colors map that is used to update funclet operand bundles. More...

void	copyColors (BasicBlock New, BasicBlock Old)
	Copy colors of block `Old` into the block `New`. More...

virtual bool	blockMayThrow (const BasicBlock *BB) const =0
	Returns true iff the block `BB` potentially may throw exception. More...

virtual bool	anyBlockMayThrow () const =0
	Returns true iff any block of the loop for which this info is contains an instruction that may throw or otherwise exit abnormally. More...

bool	allLoopPathsLeadToBlock (const Loop CurLoop, const BasicBlock BB, const DominatorTree *DT) const
	Return true if we must reach the block `BB` under assumption that the loop `CurLoop` is entered. More...

virtual void	computeLoopSafetyInfo (const Loop *CurLoop)=0
	Computes safety information for a loop checks loop body & header for the possibility of may throw exception, it takes LoopSafetyInfo and loop as argument. More...

virtual bool	isGuaranteedToExecute (const Instruction &Inst, const DominatorTree DT, const Loop CurLoop) const =0
	Returns true if the instruction in a loop is guaranteed to execute at least once (under the assumption that the loop is entered). More...

	LoopSafetyInfo ()=default

virtual	~LoopSafetyInfo ()=default

Protected Member Functions
void	computeBlockColors (const Loop *CurLoop)
	Computes block colors. More...

Detailed Description

Captures loop safety information.

It keep information for loop blocks may throw exception or otherwise exit abnormaly on any iteration of the loop which might actually execute at runtime. The primary way to consume this infromation is via isGuaranteedToExecute below, but some callers bailout or fallback to alternate reasoning if a loop contains any implicit control flow. NOTE: LoopSafetyInfo contains cached information regarding loops and their particular blocks. This information is only dropped on invocation of computeLoopSafetyInfo. If the loop or any of its block is deleted, or if any thrower instructions have been added or removed from them, or if the control flow has changed, or in case of other meaningful modifications, the LoopSafetyInfo needs to be recomputed. If a meaningful modifications to the loop were made and the info wasn't recomputed properly, the behavior of all methods except for computeLoopSafetyInfo is undefined.

Definition at line 48 of file MustExecute.h.

Constructor & Destructor Documentation

◆ LoopSafetyInfo()

llvm::LoopSafetyInfo::LoopSafetyInfo ( )

default

◆ ~LoopSafetyInfo()

virtual llvm::LoopSafetyInfo::~LoopSafetyInfo ( )

virtualdefault

Member Function Documentation

◆ allLoopPathsLeadToBlock()

bool LoopSafetyInfo::allLoopPathsLeadToBlock	(	const Loop *	CurLoop,
		const BasicBlock *	BB,
		const DominatorTree *	DT
	)		const

Return true if we must reach the block BB under assumption that the loop CurLoop is entered.

Definition at line 183 of file MustExecute.cpp.

References assert(), blockMayThrow(), CanProveNotTakenFirstIteration(), collectTransitivePredecessors(), llvm::LoopBase< BlockT, LoopT >::contains(), llvm::LoopBase< BlockT, LoopT >::getHeader(), llvm::SmallPtrSetImpl< PtrType >::insert(), and llvm::successors().

Referenced by llvm::SimpleLoopSafetyInfo::isGuaranteedToExecute(), and llvm::ICFLoopSafetyInfo::isGuaranteedToExecute().

◆ anyBlockMayThrow()

virtual bool llvm::LoopSafetyInfo::anyBlockMayThrow ( ) const

pure virtual

Returns true iff any block of the loop for which this info is contains an instruction that may throw or otherwise exit abnormally.

Implemented in llvm::ICFLoopSafetyInfo, and llvm::SimpleLoopSafetyInfo.

Referenced by llvm::SimpleLoopSafetyInfo::blockMayThrow().

◆ blockMayThrow()

virtual bool llvm::LoopSafetyInfo::blockMayThrow ( const BasicBlock * BB ) const

pure virtual

Returns true iff the block BB potentially may throw exception.

It can be false-positive in cases when we want to avoid complex analysis.

Implemented in llvm::ICFLoopSafetyInfo, and llvm::SimpleLoopSafetyInfo.

Referenced by allLoopPathsLeadToBlock().

◆ computeBlockColors()

void LoopSafetyInfo::computeBlockColors ( const Loop * CurLoop )

protected

Computes block colors.

Definition at line 97 of file MustExecute.cpp.

References llvm::classifyEHPersonality(), llvm::colorEHFunclets(), llvm::LoopBase< BlockT, LoopT >::getHeader(), llvm::BasicBlock::getParent(), llvm::Function::getPersonalityFn(), llvm::Function::hasPersonalityFn(), and llvm::isScopedEHPersonality().

Referenced by llvm::SimpleLoopSafetyInfo::computeLoopSafetyInfo(), and llvm::ICFLoopSafetyInfo::computeLoopSafetyInfo().

◆ computeLoopSafetyInfo()

virtual void llvm::LoopSafetyInfo::computeLoopSafetyInfo ( const Loop * CurLoop )

pure virtual

Computes safety information for a loop checks loop body & header for the possibility of may throw exception, it takes LoopSafetyInfo and loop as argument.

Updates safety information in LoopSafetyInfo argument. Note: This is defined to clear and reinitialize an already initialized LoopSafetyInfo. Some callers rely on this fact.

Implemented in llvm::ICFLoopSafetyInfo, and llvm::SimpleLoopSafetyInfo.