This file implements an optimization pass using memory intrinsic results. More...

#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
#include "WebAssembly.h"
#include "WebAssemblyMachineFunctionInfo.h"
#include "WebAssemblySubtarget.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/CodeGen/LiveIntervals.h"
#include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"

Macros
#define	DEBUG_TYPE "wasm-mem-intrinsic-results"

Functions
	INITIALIZE_PASS (WebAssemblyMemIntrinsicResults, DEBUG_TYPE, "Optimize memory intrinsic result values for WebAssembly", false, false) FunctionPass *llvm

static bool	replaceDominatedUses (MachineBasicBlock &MBB, MachineInstr &MI, unsigned FromReg, unsigned ToReg, const MachineRegisterInfo &MRI, MachineDominatorTree &MDT, LiveIntervals &LIS)

static bool	optimizeCall (MachineBasicBlock &MBB, MachineInstr &MI, const MachineRegisterInfo &MRI, MachineDominatorTree &MDT, LiveIntervals &LIS, const WebAssemblyTargetLowering &TLI, const TargetLibraryInfo &LibInfo)

Detailed Description

This file implements an optimization pass using memory intrinsic results.

Calls to memory intrinsics (memcpy, memmove, memset) return the destination address. They are in the form of dst_new = call @memcpy dst, src, len where dst and dst_new registers contain the same value.

This is to enable an optimization wherein uses of the dst register used in the parameter can be replaced by uses of the dst_new register used in the result, making the dst register more likely to be single-use, thus more likely to be useful to register stackifying, and potentially also exposing the call instruction itself to register stackifying. These both can reduce local.get/local.set traffic.

The LLVM intrinsics for these return void so they can't use the returned attribute and consequently aren't handled by the OptimizeReturned pass.

Definition in file WebAssemblyMemIntrinsicResults.cpp.

Macro Definition Documentation

◆ DEBUG_TYPE

#define DEBUG_TYPE "wasm-mem-intrinsic-results"

Definition at line 43 of file WebAssemblyMemIntrinsicResults.cpp.

Function Documentation

◆ INITIALIZE_PASS()

INITIALIZE_PASS	(	WebAssemblyMemIntrinsicResults	,
		DEBUG_TYPE	,
		"Optimize memory intrinsic result values for WebAssembly"	,
		false	,
		false
	)

Definition at line 75 of file WebAssemblyMemIntrinsicResults.cpp.

◆ optimizeCall()

static bool optimizeCall	(	MachineBasicBlock &	MBB,
		MachineInstr &	MI,
		const MachineRegisterInfo &	MRI,
		MachineDominatorTree &	MDT,
		LiveIntervals &	LIS,
		const WebAssemblyTargetLowering &	TLI,
		const TargetLibraryInfo &	LibInfo
	)

static

Definition at line 148 of file WebAssemblyMemIntrinsicResults.cpp.

References llvm::TargetLoweringBase::getLibcallName(), llvm::TargetLibraryInfo::getLibFunc(), llvm::MachineOperand::getSymbolName(), llvm::MachineOperand::isSymbol(), MBB, MI, MRI, Name, replaceDominatedUses(), and llvm::report_fatal_error().

◆ replaceDominatedUses()

static bool replaceDominatedUses	(	MachineBasicBlock &	MBB,
		MachineInstr &	MI,
		unsigned	FromReg,
		unsigned	ToReg,
		const MachineRegisterInfo &	MRI,
		MachineDominatorTree &	MDT,
		LiveIntervals &	LIS
	)