LLVM 20.0.0git
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llvm::ICFLoopSafetyInfo Class Reference

This implementation of LoopSafetyInfo use ImplicitControlFlowTracking to give precise answers on "may throw" queries. More...

#include "llvm/Analysis/MustExecute.h"

Inheritance diagram for llvm::ICFLoopSafetyInfo:
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Public Member Functions

bool blockMayThrow (const BasicBlock *BB) const override
 Returns true iff the block BB potentially may throw exception.
 
bool anyBlockMayThrow () const override
 Returns true iff any block of the loop for which this info is contains an instruction that may throw or otherwise exit abnormally.
 
void computeLoopSafetyInfo (const Loop *CurLoop) override
 Computes safety information for a loop checks loop body & header for the possibility of may throw exception, it takes LoopSafetyInfo and loop as argument.
 
bool isGuaranteedToExecute (const Instruction &Inst, const DominatorTree *DT, const Loop *CurLoop) const override
 Returns true if the instruction in a loop is guaranteed to execute at least once (under the assumption that the loop is entered).
 
bool doesNotWriteMemoryBefore (const BasicBlock *BB, const Loop *CurLoop) const
 Returns true if we could not execute a memory-modifying instruction before we enter BB under assumption that CurLoop is entered.
 
bool doesNotWriteMemoryBefore (const Instruction &I, const Loop *CurLoop) const
 Returns true if we could not execute a memory-modifying instruction before we execute I under assumption that CurLoop is entered.
 
void insertInstructionTo (const Instruction *Inst, const BasicBlock *BB)
 Inform the safety info that we are planning to insert a new instruction Inst into the basic block BB.
 
void removeInstruction (const Instruction *Inst)
 Inform safety info that we are planning to remove the instruction Inst from its block.
 
- Public Member Functions inherited from llvm::LoopSafetyInfo
const DenseMap< BasicBlock *, ColorVector > & getBlockColors () const
 Returns block colors map that is used to update funclet operand bundles.
 
void copyColors (BasicBlock *New, BasicBlock *Old)
 Copy colors of block Old into the block New.
 
virtual bool blockMayThrow (const BasicBlock *BB) const =0
 Returns true iff the block BB potentially may throw exception.
 
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.
 
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.
 
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.
 
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).
 
 LoopSafetyInfo ()=default
 
virtual ~LoopSafetyInfo ()=default
 

Additional Inherited Members

- Protected Member Functions inherited from llvm::LoopSafetyInfo
void computeBlockColors (const Loop *CurLoop)
 Computes block colors.
 

Detailed Description

This implementation of LoopSafetyInfo use ImplicitControlFlowTracking to give precise answers on "may throw" queries.

This implementation uses cache that should be invalidated by calling the methods insertInstructionTo and removeInstruction whenever we modify a basic block's contents by adding or removing instructions.

Definition at line 132 of file MustExecute.h.

Member Function Documentation

◆ anyBlockMayThrow()

bool ICFLoopSafetyInfo::anyBlockMayThrow ( ) const
overridevirtual

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

Implements llvm::LoopSafetyInfo.

Definition at line 75 of file MustExecute.cpp.

Referenced by llvm::promoteLoopAccessesToScalars().

◆ blockMayThrow()

bool ICFLoopSafetyInfo::blockMayThrow ( const BasicBlock BB) const
overridevirtual

Returns true iff the block BB potentially may throw exception.

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

Implements llvm::LoopSafetyInfo.

Definition at line 71 of file MustExecute.cpp.

References llvm::ImplicitControlFlowTracking::hasICF().

◆ computeLoopSafetyInfo()

void ICFLoopSafetyInfo::computeLoopSafetyInfo ( const Loop CurLoop)
overridevirtual

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.

Implements llvm::LoopSafetyInfo.

Definition at line 79 of file MustExecute.cpp.

References assert(), llvm::LoopBase< BlockT, LoopT >::blocks(), llvm::InstructionPrecedenceTracking::clear(), llvm::LoopSafetyInfo::computeBlockColors(), and llvm::ImplicitControlFlowTracking::hasICF().

Referenced by shouldInsertFreeze(), and unswitchNontrivialInvariants().

◆ doesNotWriteMemoryBefore() [1/2]

bool ICFLoopSafetyInfo::doesNotWriteMemoryBefore ( const BasicBlock BB,
const Loop CurLoop 
) const

Returns true if we could not execute a memory-modifying instruction before we enter BB under assumption that CurLoop is entered.

Definition at line 289 of file MustExecute.cpp.

References assert(), collectTransitivePredecessors(), llvm::LoopBase< BlockT, LoopT >::contains(), llvm::LoopBase< BlockT, LoopT >::getHeader(), and llvm::MemoryWriteTracking::mayWriteToMemory().

Referenced by doesNotWriteMemoryBefore(), and llvm::hoistRegion().

◆ doesNotWriteMemoryBefore() [2/2]

bool ICFLoopSafetyInfo::doesNotWriteMemoryBefore ( const Instruction I,
const Loop CurLoop 
) const

Returns true if we could not execute a memory-modifying instruction before we execute I under assumption that CurLoop is entered.

Definition at line 309 of file MustExecute.cpp.

References assert(), llvm::LoopBase< BlockT, LoopT >::contains(), doesNotWriteMemoryBefore(), I, and llvm::MemoryWriteTracking::isDominatedByMemoryWriteFromSameBlock().

◆ insertInstructionTo()

void ICFLoopSafetyInfo::insertInstructionTo ( const Instruction Inst,
const BasicBlock BB 
)

Inform the safety info that we are planning to insert a new instruction Inst into the basic block BB.

It will make all cache updates to keep it correct after this insertion.

Definition at line 93 of file MustExecute.cpp.

References llvm::InstructionPrecedenceTracking::insertInstructionTo().

Referenced by llvm::hoistRegion(), and moveInstructionBefore().

◆ isGuaranteedToExecute()

bool ICFLoopSafetyInfo::isGuaranteedToExecute ( const Instruction Inst,
const DominatorTree DT,
const Loop CurLoop 
) const
overridevirtual

◆ removeInstruction()

void ICFLoopSafetyInfo::removeInstruction ( const Instruction Inst)

Inform safety info that we are planning to remove the instruction Inst from its block.

It will make all cache updates to keep it correct after this removal.

Definition at line 99 of file MustExecute.cpp.

References llvm::InstructionPrecedenceTracking::removeInstruction().

Referenced by eraseInstruction(), and moveInstructionBefore().


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