| //===-- WebAssemblyPeephole.cpp - WebAssembly Peephole Optimiztions -------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| /// |
| /// \file |
| /// \brief Late peephole optimizations for WebAssembly. |
| /// |
| //===----------------------------------------------------------------------===// |
| |
| #include "WebAssembly.h" |
| #include "MCTargetDesc/WebAssemblyMCTargetDesc.h" |
| #include "WebAssemblyMachineFunctionInfo.h" |
| #include "llvm/CodeGen/MachineFunctionPass.h" |
| using namespace llvm; |
| |
| #define DEBUG_TYPE "wasm-peephole" |
| |
| namespace { |
| class WebAssemblyPeephole final : public MachineFunctionPass { |
| const char *getPassName() const override { |
| return "WebAssembly late peephole optimizer"; |
| } |
| |
| void getAnalysisUsage(AnalysisUsage &AU) const override { |
| AU.setPreservesCFG(); |
| MachineFunctionPass::getAnalysisUsage(AU); |
| } |
| |
| bool runOnMachineFunction(MachineFunction &MF) override; |
| |
| public: |
| static char ID; |
| WebAssemblyPeephole() : MachineFunctionPass(ID) {} |
| }; |
| } // end anonymous namespace |
| |
| char WebAssemblyPeephole::ID = 0; |
| FunctionPass *llvm::createWebAssemblyPeephole() { |
| return new WebAssemblyPeephole(); |
| } |
| |
| bool WebAssemblyPeephole::runOnMachineFunction(MachineFunction &MF) { |
| bool Changed = false; |
| |
| MachineRegisterInfo &MRI = MF.getRegInfo(); |
| WebAssemblyFunctionInfo &MFI = *MF.getInfo<WebAssemblyFunctionInfo>(); |
| |
| for (auto &MBB : MF) |
| for (auto &MI : MBB) |
| switch (MI.getOpcode()) { |
| default: |
| break; |
| case WebAssembly::STORE8_I32: |
| case WebAssembly::STORE16_I32: |
| case WebAssembly::STORE8_I64: |
| case WebAssembly::STORE16_I64: |
| case WebAssembly::STORE32_I64: |
| case WebAssembly::STORE_F32: |
| case WebAssembly::STORE_F64: |
| case WebAssembly::STORE_I32: |
| case WebAssembly::STORE_I64: { |
| // Store instructions return their value operand. If we ended up using |
| // the same register for both, replace it with a dead def so that it |
| // can use $discard instead. |
| MachineOperand &MO = MI.getOperand(0); |
| unsigned OldReg = MO.getReg(); |
| // TODO: Handle SP/physregs |
| if (OldReg == MI.getOperand(3).getReg() |
| && TargetRegisterInfo::isVirtualRegister(MI.getOperand(3).getReg())) { |
| Changed = true; |
| unsigned NewReg = MRI.createVirtualRegister(MRI.getRegClass(OldReg)); |
| MO.setReg(NewReg); |
| MO.setIsDead(); |
| MFI.stackifyVReg(NewReg); |
| MFI.addWAReg(NewReg, WebAssemblyFunctionInfo::UnusedReg); |
| } |
| } |
| } |
| |
| return Changed; |
| } |