LLVM 17.0.0git
llvm::PPCHazardRecognizer970 Class Reference

PPCHazardRecognizer970 - This class defines a finite state automata that models the dispatch logic on the PowerPC 970 (aka G5) processor. More...

#include "Target/PowerPC/PPCHazardRecognizers.h"

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## Public Member Functions

PPCHazardRecognizer970 (const ScheduleDAG &DAG)

HazardType getHazardType (SUnit *SU, int Stalls) override
getHazardType - We return hazard for any non-branch instruction that would terminate the dispatch group.

void EmitInstruction (SUnit *SU) override
EmitInstruction - This callback is invoked when an instruction is emitted, to advance the hazard state.

AdvanceCycle - This callback is invoked whenever the next top-down instruction to be scheduled cannot issue in the current cycle, either because of latency or resource conflicts.

void Reset () override
Reset - This callback is invoked when a new block of instructions is about to be schedule.

Public Member Functions inherited from llvm::ScheduleHazardRecognizer
ScheduleHazardRecognizer ()=default

virtual ~ScheduleHazardRecognizer ()

bool isEnabled () const

virtual bool atIssueLimit () const
atIssueLimit - Return true if no more instructions may be issued in this cycle.

virtual HazardType getHazardType (SUnit *, int Stalls=0)
getHazardType - Return the hazard type of emitting this node.

virtual void Reset ()
Reset - This callback is invoked when a new block of instructions is about to be schedule.

virtual void EmitInstruction (SUnit *)
EmitInstruction - This callback is invoked when an instruction is emitted, to advance the hazard state.

virtual void EmitInstruction (MachineInstr *)
This overload will be used when the hazard recognizer is being used by a non-scheduling pass, which does not use SUnits.

virtual unsigned PreEmitNoops (SUnit *)
PreEmitNoops - This callback is invoked prior to emitting an instruction.

virtual unsigned PreEmitNoops (MachineInstr *)
This overload will be used when the hazard recognizer is being used by a non-scheduling pass, which does not use SUnits.

virtual bool ShouldPreferAnother (SUnit *)
ShouldPreferAnother - This callback may be invoked if getHazardType returns NoHazard.

AdvanceCycle - This callback is invoked whenever the next top-down instruction to be scheduled cannot issue in the current cycle, either because of latency or resource conflicts.

virtual void RecedeCycle ()
RecedeCycle - This callback is invoked whenever the next bottom-up instruction to be scheduled cannot issue in the current cycle, either because of latency or resource conflicts.

virtual void EmitNoop ()
EmitNoop - This callback is invoked when a noop was added to the instruction stream.

virtual void EmitNoops (unsigned Quantity)
EmitNoops - This callback is invoked when noops were added to the instruction stream.

Public Types inherited from llvm::ScheduleHazardRecognizer
enum  HazardType { NoHazard , Hazard , NoopHazard }

Protected Attributes inherited from llvm::ScheduleHazardRecognizer
MaxLookAhead - Indicate the number of cycles in the scoreboard state.

## Detailed Description

PPCHazardRecognizer970 - This class defines a finite state automata that models the dispatch logic on the PowerPC 970 (aka G5) processor.

This promotes good dispatch group formation and implements noop insertion to avoid structural hazards that cause significant performance penalties (e.g. setting the CTR register then branching through it within a dispatch group), or storing then loading from the same address within a dispatch group.

Definition at line 55 of file PPCHazardRecognizers.h.

## ◆ PPCHazardRecognizer970()

 PPCHazardRecognizer970::PPCHazardRecognizer970 ( const ScheduleDAG & DAG )

Definition at line 262 of file PPCHazardRecognizers.cpp.

## Member Function Documentation

overridevirtual

AdvanceCycle - This callback is invoked whenever the next top-down instruction to be scheduled cannot issue in the current cycle, either because of latency or resource conflicts.

This should increment the internal state of the hazard recognizer so that previously "Hazard" instructions will now not be hazards.

Reimplemented from llvm::ScheduleHazardRecognizer.

Definition at line 423 of file PPCHazardRecognizers.cpp.

References assert().

## ◆ EmitInstruction()

 void PPCHazardRecognizer970::EmitInstruction ( SUnit * )
overridevirtual

EmitInstruction - This callback is invoked when an instruction is emitted, to advance the hazard state.

Reimplemented from llvm::ScheduleHazardRecognizer.

Definition at line 385 of file PPCHazardRecognizers.cpp.

## ◆ getHazardType()

 ScheduleHazardRecognizer::HazardType PPCHazardRecognizer970::getHazardType ( SUnit * SU, int Stalls )
overridevirtual

getHazardType - We return hazard for any non-branch instruction that would terminate the dispatch group.

We turn NoopHazard for any instructions that wouldn't terminate the dispatch group that would cause a pipeline flush.

Reimplemented from llvm::ScheduleHazardRecognizer.

Definition at line 324 of file PPCHazardRecognizers.cpp.

## ◆ Reset()

 void PPCHazardRecognizer970::Reset ( )
overridevirtual

Reset - This callback is invoked when a new block of instructions is about to be schedule.

The hazard state should be set to an initialized state.

Reimplemented from llvm::ScheduleHazardRecognizer.

Definition at line 430 of file PPCHazardRecognizers.cpp.

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