WebAssemblyRegStackify.cpp File Reference

This file implements a register stacking pass. More...

#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
#include "WebAssembly.h"
#include "WebAssemblyDebugValueManager.h"
#include "WebAssemblyMachineFunctionInfo.h"
#include "WebAssemblySubtarget.h"
#include "WebAssemblyUtilities.h"
#include "llvm/CodeGen/LiveIntervals.h"
#include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/IR/GlobalAlias.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include <iterator>

Go to the source code of this file.

Macros
#define	DEBUG_TYPE   "wasm-reg-stackify"

Functions
	INITIALIZE_PASS (WebAssemblyRegStackify, DEBUG_TYPE, "Reorder instructions to use the WebAssembly value stack", false, false) FunctionPass *llvm
static void	imposeStackOrdering (MachineInstr *MI)
static void	convertImplicitDefToConstZero (MachineInstr *MI, MachineRegisterInfo &MRI, const TargetInstrInfo *TII, MachineFunction &MF)
static void	queryCallee (const MachineInstr &MI, bool &Read, bool &Write, bool &Effects, bool &StackPointer)
static void	query (const MachineInstr &MI, bool &Read, bool &Write, bool &Effects, bool &StackPointer)
static bool	shouldRematerialize (const MachineInstr &Def, const WebAssemblyInstrInfo *TII)
static MachineInstr *	getVRegDef (unsigned Reg, const MachineInstr *Insert, const MachineRegisterInfo &MRI, const LiveIntervals *LIS)
static bool	hasSingleUse (unsigned Reg, MachineRegisterInfo &MRI, WebAssemblyFunctionInfo &MFI, bool Optimize, MachineInstr *Def, LiveIntervals *LIS)
static bool	isSafeToMove (const MachineOperand *Def, const MachineOperand *Use, const MachineInstr *Insert, const WebAssemblyFunctionInfo &MFI, const MachineRegisterInfo &MRI, bool Optimize)
static bool	oneUseDominatesOtherUses (unsigned Reg, const MachineOperand &OneUse, const MachineBasicBlock &MBB, const MachineRegisterInfo &MRI, const MachineDominatorTree &MDT, LiveIntervals &LIS, WebAssemblyFunctionInfo &MFI)
	Test whether OneUse, a use of Reg, dominates all of Reg's other uses.
static unsigned	getTeeOpcode (const TargetRegisterClass *RC)
	Get the appropriate tee opcode for the given register class.
static void	shrinkToUses (LiveInterval &LI, LiveIntervals &LIS)
static MachineInstr *	moveForSingleUse (unsigned Reg, MachineOperand &Op, MachineInstr *Def, MachineBasicBlock &MBB, MachineInstr *Insert, LiveIntervals *LIS, WebAssemblyFunctionInfo &MFI, MachineRegisterInfo &MRI)
	A single-use def in the same block with no intervening memory or register dependencies; move the def down and nest it with the current instruction.
static MachineInstr *	getPrevNonDebugInst (MachineInstr *MI)
static MachineInstr *	rematerializeCheapDef (unsigned Reg, MachineOperand &Op, MachineInstr &Def, MachineBasicBlock::instr_iterator Insert, LiveIntervals &LIS, WebAssemblyFunctionInfo &MFI, MachineRegisterInfo &MRI, const WebAssemblyInstrInfo *TII)
	A trivially cloneable instruction; clone it and nest the new copy with the current instruction.
static MachineInstr *	moveAndTeeForMultiUse (unsigned Reg, MachineOperand &Op, MachineInstr *Def, MachineBasicBlock &MBB, MachineInstr *Insert, LiveIntervals &LIS, WebAssemblyFunctionInfo &MFI, MachineRegisterInfo &MRI, const WebAssemblyInstrInfo *TII)
	A multiple-use def in the same block with no intervening memory or register dependencies; move the def down, nest it with the current instruction, and insert a tee to satisfy the rest of the uses.

Detailed Description

This file implements a register stacking pass.

This pass reorders instructions to put register uses and defs in an order such that they form single-use expression trees. Registers fitting this form are then marked as "stackified", meaning references to them are replaced by "push" and "pop" from the value stack.

This is primarily a code size optimization, since temporary values on the value stack don't need to be named.

Definition in file WebAssemblyRegStackify.cpp.

Macro Definition Documentation

DEBUG_TYPE

#define DEBUG_TYPE   "wasm-reg-stackify"

Definition at line 40 of file WebAssemblyRegStackify.cpp.

Function Documentation

convertImplicitDefToConstZero()

void convertImplicitDefToConstZero ( MachineInstr * MI, MachineRegisterInfo & MRI, const TargetInstrInfo * TII, MachineFunction & MF )

static

Definition at line 102 of file WebAssemblyRegStackify.cpp.

References assert(), llvm::cast(), llvm::MachineOperand::CreateFPImm(), llvm::MachineOperand::CreateImm(), llvm::Function::getContext(), llvm::Type::getDoubleTy(), llvm::Type::getFloatTy(), llvm::MachineFunction::getFunction(), llvm::Constant::getNullValue(), llvm_unreachable, MI, MRI, and TII.

getPrevNonDebugInst()

MachineInstr * getPrevNonDebugInst ( MachineInstr * MI )

static

Definition at line 592 of file WebAssemblyRegStackify.cpp.

References I, and MI.

Referenced by rematerializeCheapDef().

getTeeOpcode()

unsigned getTeeOpcode ( const TargetRegisterClass * RC )

static

Get the appropriate tee opcode for the given register class.

Definition at line 520 of file WebAssemblyRegStackify.cpp.

References llvm_unreachable.

Referenced by moveAndTeeForMultiUse().

getVRegDef()

MachineInstr * getVRegDef ( unsigned Reg, const MachineInstr * Insert, const MachineRegisterInfo & MRI, const LiveIntervals * LIS )

static

Definition at line 269 of file WebAssemblyRegStackify.cpp.

References llvm::LiveIntervals::getInstructionFromIndex(), llvm::LiveIntervals::getInstructionIndex(), llvm::LiveIntervals::getInterval(), llvm::LiveRange::getVNInfoBefore(), MRI, and Reg.

hasSingleUse()

bool hasSingleUse ( unsigned Reg, MachineRegisterInfo & MRI, WebAssemblyFunctionInfo & MFI, bool Optimize, MachineInstr * Def, LiveIntervals * LIS )

static

Definition at line 289 of file WebAssemblyRegStackify.cpp.

References assert(), llvm::WebAssemblyFunctionInfo::getFrameBaseVreg(), llvm::LiveIntervals::getInstructionIndex(), llvm::LiveIntervals::getInterval(), llvm::SlotIndex::getRegSlot(), llvm::LiveRange::getVNInfoAt(), I, llvm::WebAssemblyFunctionInfo::isFrameBaseVirtual(), MRI, llvm::Optimize, llvm::LiveRange::Query(), and Reg.

imposeStackOrdering()

void imposeStackOrdering ( MachineInstr * MI )

static

Definition at line 86 of file WebAssemblyRegStackify.cpp.

References llvm::MachineOperand::CreateReg(), and MI.

Referenced by moveAndTeeForMultiUse(), moveForSingleUse(), and rematerializeCheapDef().

INITIALIZE_PASS()

INITIALIZE_PASS	(	WebAssemblyRegStackify	,
		DEBUG_TYPE	,
		"Reorder instructions to use the WebAssembly value stack"	,
		false	,
		false	)

Definition at line 75 of file WebAssemblyRegStackify.cpp.

References llvm::createWebAssemblyRegStackify(), and DEBUG_TYPE.

isSafeToMove()

bool isSafeToMove ( const MachineOperand * Def, const MachineOperand * Use, const MachineInstr * Insert, const WebAssemblyFunctionInfo & MFI, const MachineRegisterInfo & MRI, bool Optimize )

static

Definition at line 334 of file WebAssemblyRegStackify.cpp.

References assert(), llvm::iterator_range< IteratorT >::begin(), D(), llvm::MachineInstr::defs(), llvm::drop_begin(), E(), llvm::SmallVectorTemplateCommon< T, typename >::empty(), llvm::MachineInstr::getOpcode(), llvm::MachineInstr::getParent(), I, llvm::WebAssembly::isCatch(), MBB, MRI, llvm::MachineInstr::operands(), llvm::Optimize, llvm::SmallVectorTemplateBase< T, bool >::push_back(), query(), llvm::Read, Reg, and llvm::Write.

moveAndTeeForMultiUse()

MachineInstr * moveAndTeeForMultiUse ( unsigned Reg, MachineOperand & Op, MachineInstr * Def, MachineBasicBlock & MBB, MachineInstr * Insert, LiveIntervals & LIS, WebAssemblyFunctionInfo & MFI, MachineRegisterInfo & MRI, const WebAssemblyInstrInfo * TII )

static

A multiple-use def in the same block with no intervening memory or register dependencies; move the def down, nest it with the current instruction, and insert a tee to satisfy the rest of the uses.

As an illustration, rewrite this:

Reg = INST ... // Def INST ..., Reg, ... // Insert INST ..., Reg, ... INST ..., Reg, ...

to this:

DefReg = INST ... // Def (to become the new Insert) TeeReg, Reg = TEE_... DefReg INST ..., TeeReg, ... // Insert INST ..., Reg, ... INST ..., Reg, ...

with DefReg and TeeReg stackified. This eliminates a local.get from the resulting code.

Definition at line 665 of file WebAssemblyRegStackify.cpp.

References llvm::MachineInstrBuilder::addReg(), llvm::BuildMI(), llvm::WebAssemblyDebugValueManager::cloneSink(), llvm::LiveIntervals::createAndComputeVirtRegInterval(), llvm::dbgs(), llvm::VNInfo::def, llvm::RegState::Define, llvm::MachineInstr::dump(), llvm::LiveRange::FindSegmentContaining(), llvm::LiveIntervals::getInstructionIndex(), llvm::LiveIntervals::getInterval(), llvm::SlotIndex::getRegSlot(), getTeeOpcode(), llvm::getUndefRegState(), llvm::LiveRange::getVNInfoAt(), llvm::LiveIntervals::handleMove(), I, imposeStackOrdering(), llvm::LiveIntervals::InsertMachineInstrInMaps(), llvm::MachineOperand::isDead(), LLVM_DEBUG, MBB, MRI, Reg, shrinkToUses(), llvm::WebAssemblyDebugValueManager::sink(), llvm::WebAssemblyFunctionInfo::stackifyVReg(), TII, and llvm::WebAssemblyDebugValueManager::updateReg().

moveForSingleUse()

MachineInstr * moveForSingleUse ( unsigned Reg, MachineOperand & Op, MachineInstr * Def, MachineBasicBlock & MBB, MachineInstr * Insert, LiveIntervals * LIS, WebAssemblyFunctionInfo & MFI, MachineRegisterInfo & MRI )

static

A single-use def in the same block with no intervening memory or register dependencies; move the def down and nest it with the current instruction.

Definition at line 550 of file WebAssemblyRegStackify.cpp.

References llvm::LiveIntervals::createAndComputeVirtRegInterval(), llvm::dbgs(), llvm::LiveIntervals::getInstructionIndex(), llvm::LiveIntervals::getInterval(), llvm::SlotIndex::getRegSlot(), llvm::LiveIntervals::handleMove(), imposeStackOrdering(), LLVM_DEBUG, MBB, MRI, Reg, llvm::LiveRange::removeSegment(), llvm::WebAssemblyDebugValueManager::sink(), llvm::WebAssemblyFunctionInfo::stackifyVReg(), and llvm::WebAssemblyDebugValueManager::updateReg().

oneUseDominatesOtherUses()

bool oneUseDominatesOtherUses ( unsigned Reg, const MachineOperand & OneUse, const MachineBasicBlock & MBB, const MachineRegisterInfo & MRI, const MachineDominatorTree & MDT, LiveIntervals & LIS, WebAssemblyFunctionInfo & MFI )

static

Test whether OneUse, a use of Reg, dominates all of Reg's other uses.

Definition at line 462 of file WebAssemblyRegStackify.cpp.

References assert(), llvm::MachineDominatorTree::dominates(), llvm::MachineInstr::getDesc(), llvm::LiveIntervals::getInstructionIndex(), llvm::LiveIntervals::getInterval(), llvm::MCInstrDesc::getNumDefs(), llvm::MachineInstr::getOperand(), llvm::MachineOperand::getParent(), llvm::MachineOperand::getReg(), llvm::LiveRange::getVNInfoBefore(), llvm::MachineOperand::isReg(), llvm::Register::isVirtual(), llvm::WebAssemblyFunctionInfo::isVRegStackified(), MBB, MRI, and Reg.

query()

void query ( const MachineInstr & MI, bool & Read, bool & Write, bool & Effects, bool & StackPointer )

static

Definition at line 169 of file WebAssemblyRegStackify.cpp.

References assert(), MI, queryCallee(), llvm::Read, and llvm::Write.

Referenced by isSafeToMove().

queryCallee()

void queryCallee ( const MachineInstr & MI, bool & Read, bool & Write, bool & Effects, bool & StackPointer )

static

Definition at line 137 of file WebAssemblyRegStackify.cpp.

References llvm::dyn_cast(), F, llvm::WebAssembly::getCalleeOp(), llvm::MachineOperand::getGlobal(), llvm::MachineOperand::isGlobal(), MI, llvm::Read, and llvm::Write.

Referenced by query().

rematerializeCheapDef()

MachineInstr * rematerializeCheapDef ( unsigned Reg, MachineOperand & Op, MachineInstr & Def, MachineBasicBlock::instr_iterator Insert, LiveIntervals & LIS, WebAssemblyFunctionInfo & MFI, MachineRegisterInfo & MRI, const WebAssemblyInstrInfo * TII )

static

A trivially cloneable instruction; clone it and nest the new copy with the current instruction.

Definition at line 602 of file WebAssemblyRegStackify.cpp.

References assert(), llvm::WebAssemblyDebugValueManager::cloneSink(), llvm::LiveIntervals::createAndComputeVirtRegInterval(), llvm::dbgs(), llvm::dump(), llvm::MachineInstr::dump(), llvm::MCRegister::from(), llvm::SlotIndex::getDeadSlot(), llvm::LiveIntervals::getInstructionIndex(), llvm::LiveIntervals::getInterval(), getPrevNonDebugInst(), llvm::SlotIndex::getRegSlot(), imposeStackOrdering(), llvm::LiveIntervals::InsertMachineInstrInMaps(), IsDead, llvm::LiveRange::liveAt(), LLVM_DEBUG, MRI, Reg, llvm::WebAssemblyDebugValueManager::removeDef(), llvm::LiveIntervals::removeInterval(), llvm::LiveIntervals::RemoveMachineInstrFromMaps(), llvm::LiveIntervals::removePhysRegDefAt(), shrinkToUses(), llvm::WebAssemblyFunctionInfo::stackifyVReg(), and TII.

shouldRematerialize()

bool shouldRematerialize ( const MachineInstr & Def, const WebAssemblyInstrInfo * TII )

static

Definition at line 261 of file WebAssemblyRegStackify.cpp.

References TII.

shrinkToUses()

void shrinkToUses ( LiveInterval & LI, LiveIntervals & LIS )

static

Definition at line 541 of file WebAssemblyRegStackify.cpp.

References llvm::LiveIntervals::shrinkToUses(), and llvm::LiveIntervals::splitSeparateComponents().

Referenced by moveAndTeeForMultiUse(), and rematerializeCheapDef().