class ScheduleHazardRecognizer

Declaration

class ScheduleHazardRecognizer { /* full declaration omitted */ };

Description

HazardRecognizer - This determines whether or not an instruction can be issued this cycle, and whether or not a noop needs to be inserted to handle the hazard.

Declared at: llvm/include/llvm/CodeGen/ScheduleHazardRecognizer.h:25

Member Variables

protected unsigned int MaxLookAhead = 0
MaxLookAhead - Indicate the number of cycles in the scoreboard state. Important to restore the state after backtracking. Additionally, MaxLookAhead=0 identifies a fake recognizer, allowing the client to bypass virtual calls. Currently the PostRA scheduler ignores it.

Method Overview

Methods

virtual void AdvanceCycle()

Description

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.

Declared at: llvm/include/llvm/CodeGen/ScheduleHazardRecognizer.h:104

virtual void EmitInstruction(llvm::SUnit*)

Description

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

Declared at: llvm/include/llvm/CodeGen/ScheduleHazardRecognizer.h:71

Parameters

llvm::SUnit* 

virtual void EmitInstruction(llvm::MachineInstr*)

Description

This overload will be used when the hazard recognizer is being used by a non-scheduling pass, which does not use SUnits.

Declared at: llvm/include/llvm/CodeGen/ScheduleHazardRecognizer.h:75

Parameters

llvm::MachineInstr* 

virtual void EmitNoop()

Description

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

Declared at: llvm/include/llvm/CodeGen/ScheduleHazardRecognizer.h:113

virtual unsigned int PreEmitNoops(llvm::SUnit*)

Description

PreEmitNoops - This callback is invoked prior to emitting an instruction. It should return the number of noops to emit prior to the provided instruction. Note: This is only used during PostRA scheduling. EmitNoop is not called for these noops.

Declared at: llvm/include/llvm/CodeGen/ScheduleHazardRecognizer.h:82

Parameters

llvm::SUnit* 

virtual unsigned int PreEmitNoops(
    llvm::MachineInstr*)

Description

This overload will be used when the hazard recognizer is being used by a non-scheduling pass, which does not use SUnits.

Declared at: llvm/include/llvm/CodeGen/ScheduleHazardRecognizer.h:88

Parameters

llvm::MachineInstr* 

virtual void RecedeCycle()

Description

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.

Declared at: llvm/include/llvm/CodeGen/ScheduleHazardRecognizer.h:109

virtual void Reset()

Description

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.

Declared at: llvm/include/llvm/CodeGen/ScheduleHazardRecognizer.h:67

ScheduleHazardRecognizer()

Declared at: llvm/include/llvm/CodeGen/ScheduleHazardRecognizer.h:34

virtual bool ShouldPreferAnother(llvm::SUnit*)

Description

ShouldPreferAnother - This callback may be invoked if getHazardType returns NoHazard. If, even though there is no hazard, it would be better to schedule another available instruction, this callback should return true.

Declared at: llvm/include/llvm/CodeGen/ScheduleHazardRecognizer.h:95

Parameters

llvm::SUnit* 

virtual bool atIssueLimit() const

Description

atIssueLimit - Return true if no more instructions may be issued in this cycle. FIXME: remove this once MachineScheduler is the only client.

Declared at: llvm/include/llvm/CodeGen/ScheduleHazardRecognizer.h:51

virtual llvm::ScheduleHazardRecognizer::HazardType
getHazardType(llvm::SUnit* m, int Stalls = 0)

Description

getHazardType - Return the hazard type of emitting this node. There are three possible results. Either: * NoHazard: it is legal to issue this instruction on this cycle. * Hazard: issuing this instruction would stall the machine. If some other instruction is available, issue it first. * NoopHazard: issuing this instruction would break the program. If some other instruction can be issued, do so, otherwise issue a noop.

Declared at: llvm/include/llvm/CodeGen/ScheduleHazardRecognizer.h:60

Parameters

llvm::SUnit* m
int Stalls = 0

unsigned int getMaxLookAhead() const

Declared at: llvm/include/llvm/CodeGen/ScheduleHazardRecognizer.h:43

bool isEnabled() const

Declared at: llvm/include/llvm/CodeGen/ScheduleHazardRecognizer.h:45

virtual ~ScheduleHazardRecognizer()

Declared at: llvm/include/llvm/CodeGen/ScheduleHazardRecognizer.h:35