SIInsertWaitcnts.cpp File Reference

Insert wait instructions for memory reads and writes. More...

#include "AMDGPU.h"
#include "AMDGPUHWEvents.h"
#include "AMDGPUWaitcntUtils.h"
#include "GCNSubtarget.h"
#include "MCTargetDesc/AMDGPUMCTargetDesc.h"
#include "SIMachineFunctionInfo.h"
#include "Utils/AMDGPUBaseInfo.h"
#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/Sequence.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/MachinePassManager.h"
#include "llvm/CodeGen/MachinePostDominators.h"
#include "llvm/IR/Dominators.h"
#include "llvm/InitializePasses.h"
#include "llvm/TargetParser/AMDGPUTargetParser.h"

Go to the source code of this file.

Macros
#define	DEBUG_TYPE   "si-insert-waitcnts"

Typedefs
using	HWEventSet = AMDGPU::HWEventSet
using	HWEvent = AMDGPU::HWEvent

Functions
	INITIALIZE_PASS_BEGIN (SIInsertWaitcntsLegacy, DEBUG_TYPE, "SI Insert Waitcnts", false, false) INITIALIZE_PASS_END(SIInsertWaitcntsLegacy
static bool	updateOperandIfDifferent (MachineInstr &MI, AMDGPU::OpName OpName, unsigned NewEnc)
static bool	isWaitInstr (MachineInstr &Inst)

Variables
static cl::opt< bool >	ForceEmitZeroFlag ("amdgpu-waitcnt-forcezero", cl::desc("Force all waitcnt instrs to be emitted as " "s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)"), cl::init(false), cl::Hidden)
static cl::opt< bool >	ForceEmitZeroLoadFlag ("amdgpu-waitcnt-load-forcezero", cl::desc("Force all waitcnt load counters to wait until 0"), cl::init(false), cl::Hidden)
static cl::opt< bool >	ExpertSchedulingModeFlag ("amdgpu-expert-scheduling-mode", cl::desc("Enable expert scheduling mode 2 for all functions (GFX12+ only)"), cl::init(false), cl::Hidden)
	DEBUG_TYPE
SI Insert	Waitcnts
SI Insert	false

Detailed Description

Insert wait instructions for memory reads and writes.

Memory reads and writes are issued asynchronously, so we need to insert S_WAITCNT instructions when we want to access any of their results or overwrite any register that's used asynchronously.

TODO: This pass currently keeps one timeline per hardware counter. A more finely-grained approach that keeps one timeline per event type could sometimes get away with generating weaker s_waitcnt instructions. For example, when both SMEM and LDS are in flight and we need to wait for the i-th-last LDS instruction, then an lgkmcnt(i) is actually sufficient, but the pass will currently generate a conservative lgkmcnt(0) because multiple event types are in flight.

Definition in file SIInsertWaitcnts.cpp.

Macro Definition Documentation

DEBUG_TYPE

#define DEBUG_TYPE   "si-insert-waitcnts"

Definition at line 50 of file SIInsertWaitcnts.cpp.

Typedef Documentation

HWEvent

using HWEvent = AMDGPU::HWEvent

Definition at line 48 of file SIInsertWaitcnts.cpp.

HWEventSet

using HWEventSet = AMDGPU::HWEventSet

Definition at line 47 of file SIInsertWaitcnts.cpp.

Function Documentation

INITIALIZE_PASS_BEGIN()

INITIALIZE_PASS_BEGIN	(	SIInsertWaitcntsLegacy	,
		DEBUG_TYPE	,
		"SI Insert Waitcnts"	,
		false	,
		false	)

References DEBUG_TYPE, and INITIALIZE_PASS_DEPENDENCY.

isWaitInstr()

bool isWaitInstr ( MachineInstr & Inst )

static

Definition at line 2866 of file SIInsertWaitcnts.cpp.

References llvm::AMDGPU::counterTypeForInstr(), llvm::SIInstrInfo::getNonSoftWaitcntOpcode(), llvm::MachineInstr::getOpcode(), llvm::MachineInstr::getOperand(), llvm::MachineOperand::getReg(), and isReg().

updateOperandIfDifferent()

bool updateOperandIfDifferent ( MachineInstr & MI, AMDGPU::OpName OpName, unsigned NewEnc )

static

Definition at line 1577 of file SIInsertWaitcnts.cpp.

References assert(), llvm::MachineOperand::getImm(), MI, OpIdx, and llvm::MachineOperand::setImm().

Variable Documentation

DEBUG_TYPE

DEBUG_TYPE

Definition at line 1566 of file SIInsertWaitcnts.cpp.

ExpertSchedulingModeFlag

cl::opt< bool > ExpertSchedulingModeFlag("amdgpu-expert-scheduling-mode", cl::desc("Enable expert scheduling mode 2 for all functions (GFX12+ only)"), cl::init(false), cl::Hidden) ( "amdgpu-expert-scheduling-mode" , cl::desc("Enable expert scheduling mode 2 for all functions (GFX12+ only)") , cl::init(false) , cl::Hidden  )

static

false

SI Insert false

Definition at line 1567 of file SIInsertWaitcnts.cpp.

ForceEmitZeroFlag

cl::opt< bool > ForceEmitZeroFlag("amdgpu-waitcnt-forcezero", cl::desc("Force all waitcnt instrs to be emitted as " "s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)"), cl::init(false), cl::Hidden) ( "amdgpu-waitcnt-forcezero" , cl::desc("Force all waitcnt instrs to be emitted as " "s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)") , cl::init(false) , cl::Hidden  )

static

ForceEmitZeroLoadFlag

cl::opt< bool > ForceEmitZeroLoadFlag("amdgpu-waitcnt-load-forcezero", cl::desc("Force all waitcnt load counters to wait until 0"), cl::init(false), cl::Hidden) ( "amdgpu-waitcnt-load-forcezero" , cl::desc("Force all waitcnt load counters to wait until 0") , cl::init(false) , cl::Hidden  )

static

Waitcnts

SI Insert Waitcnts

Definition at line 1566 of file SIInsertWaitcnts.cpp.