llvm::ImplicitControlFlowTracking Class Reference

This class allows to keep track on instructions with implicit control flow. More...

#include "llvm/Analysis/InstructionPrecedenceTracking.h"

Inheritance diagram for llvm::ImplicitControlFlowTracking:

Public Member Functions
const Instruction *	getFirstICFI (const BasicBlock *BB)
	Returns the topmost instruction with implicit control flow from the given basic block.
bool	hasICF (const BasicBlock *BB)
	Returns true if at least one instruction from the given basic block has implicit control flow.
bool	isDominatedByICFIFromSameBlock (const Instruction *Insn)
	Returns true if the first ICFI of Insn's block exists and dominates Insn.
bool	isSpecialInstruction (const Instruction *Insn) const override
	A predicate that defines whether or not the instruction Insn is considered special and needs to be tracked.
Public Member Functions inherited from llvm::InstructionPrecedenceTracking
LLVM_ABI void	insertInstructionTo (const Instruction *Inst, const BasicBlock *BB)
	Notifies this tracking that we are going to insert a new instruction Inst to the basic block BB.
LLVM_ABI void	removeInstruction (const Instruction *Inst)
	Notifies this tracking that we are going to remove the instruction Inst It makes all necessary updates to internal caches to keep them consistent.
LLVM_ABI void	removeUsersOf (const Instruction *Inst)
	Notifies this tracking that we are going to replace all uses of Inst.
LLVM_ABI void	clear ()
	Invalidates all information from this tracking.

Additional Inherited Members
Protected Member Functions inherited from llvm::InstructionPrecedenceTracking
LLVM_ABI const Instruction *	getFirstSpecialInstruction (const BasicBlock *BB)
	Returns the topmost special instruction from the block BB.
LLVM_ABI bool	hasSpecialInstructions (const BasicBlock *BB)
	Returns true iff at least one instruction from the basic block BB is special.
LLVM_ABI bool	isPreceededBySpecialInstruction (const Instruction *Insn)
	Returns true iff the first special instruction of Insn's block exists and dominates Insn.
virtual	~InstructionPrecedenceTracking ()=default

Detailed Description

This class allows to keep track on instructions with implicit control flow.

These are instructions that may not pass execution to their successors. For example, throwing calls and guards do not always do this. If we need to know for sure that some instruction is guaranteed to execute if the given block is reached, then we need to make sure that there is no implicit control flow instruction (ICFI) preceding it. For example, this check is required if we perform PRE moving non-speculable instruction to other place.

Definition at line 98 of file InstructionPrecedenceTracking.h.

Member Function Documentation

getFirstICFI()

const Instruction * llvm::ImplicitControlFlowTracking::getFirstICFI ( const BasicBlock * BB )

inline

Returns the topmost instruction with implicit control flow from the given basic block.

Returns nullptr if there is no such instructions in the block.

Definition at line 103 of file InstructionPrecedenceTracking.h.

References llvm::InstructionPrecedenceTracking::getFirstSpecialInstruction().

hasICF()

bool llvm::ImplicitControlFlowTracking::hasICF ( const BasicBlock * BB )

inline

Returns true if at least one instruction from the given basic block has implicit control flow.

Definition at line 109 of file InstructionPrecedenceTracking.h.

References llvm::InstructionPrecedenceTracking::hasSpecialInstructions().

isDominatedByICFIFromSameBlock()

bool llvm::ImplicitControlFlowTracking::isDominatedByICFIFromSameBlock ( const Instruction * Insn )

inline

Returns true if the first ICFI of Insn's block exists and dominates Insn.

Definition at line 114 of file InstructionPrecedenceTracking.h.

References llvm::InstructionPrecedenceTracking::isPreceededBySpecialInstruction().

isSpecialInstruction()

bool ImplicitControlFlowTracking::isSpecialInstruction ( const Instruction * Insn ) const

overridevirtual

A predicate that defines whether or not the instruction Insn is considered special and needs to be tracked.

Implementing this method in children classes allows to implement tracking of implicit control flow, memory writing instructions or any other kinds of instructions we might be interested in.

Implements llvm::InstructionPrecedenceTracking.

Definition at line 130 of file InstructionPrecedenceTracking.cpp.

References llvm::isGuaranteedToTransferExecutionToSuccessor().

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

• include/llvm/Analysis/InstructionPrecedenceTracking.h
• lib/Analysis/InstructionPrecedenceTracking.cpp