108 lines · cpp
1//===-- WebAssemblyRegNumbering.cpp - Register Numbering ------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8///9/// \file10/// This file implements a pass which assigns WebAssembly register11/// numbers for CodeGen virtual registers.12///13//===----------------------------------------------------------------------===//14 15#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"16#include "WebAssembly.h"17#include "WebAssemblyMachineFunctionInfo.h"18#include "WebAssemblyUtilities.h"19#include "llvm/CodeGen/MachineFrameInfo.h"20#include "llvm/CodeGen/MachineFunction.h"21#include "llvm/CodeGen/MachineRegisterInfo.h"22#include "llvm/CodeGen/Passes.h"23#include "llvm/Support/Debug.h"24#include "llvm/Support/raw_ostream.h"25using namespace llvm;26 27#define DEBUG_TYPE "wasm-reg-numbering"28 29namespace {30class WebAssemblyRegNumbering final : public MachineFunctionPass {31 StringRef getPassName() const override {32 return "WebAssembly Register Numbering";33 }34 35 void getAnalysisUsage(AnalysisUsage &AU) const override {36 AU.setPreservesCFG();37 MachineFunctionPass::getAnalysisUsage(AU);38 }39 40 bool runOnMachineFunction(MachineFunction &MF) override;41 42public:43 static char ID; // Pass identification, replacement for typeid44 WebAssemblyRegNumbering() : MachineFunctionPass(ID) {}45};46} // end anonymous namespace47 48char WebAssemblyRegNumbering::ID = 0;49INITIALIZE_PASS(WebAssemblyRegNumbering, DEBUG_TYPE,50 "Assigns WebAssembly register numbers for virtual registers",51 false, false)52 53FunctionPass *llvm::createWebAssemblyRegNumbering() {54 return new WebAssemblyRegNumbering();55}56 57bool WebAssemblyRegNumbering::runOnMachineFunction(MachineFunction &MF) {58 LLVM_DEBUG(dbgs() << "********** Register Numbering **********\n"59 "********** Function: "60 << MF.getName() << '\n');61 62 WebAssemblyFunctionInfo &MFI = *MF.getInfo<WebAssemblyFunctionInfo>();63 MachineRegisterInfo &MRI = MF.getRegInfo();64 65 MFI.initWARegs(MRI);66 67 // WebAssembly argument registers are in the same index space as local68 // variables. Assign the numbers for them first.69 MachineBasicBlock &EntryMBB = MF.front();70 for (MachineInstr &MI : EntryMBB) {71 if (!WebAssembly::isArgument(MI.getOpcode()))72 break;73 74 int64_t Imm = MI.getOperand(1).getImm();75 LLVM_DEBUG(dbgs() << "Arg VReg " << printReg(MI.getOperand(0).getReg())76 << " -> WAReg " << Imm << "\n");77 MFI.setWAReg(MI.getOperand(0).getReg(), Imm);78 }79 80 // Then assign regular WebAssembly registers for all remaining used81 // virtual registers. TODO: Consider sorting the registers by frequency of82 // use, to maximize usage of small immediate fields.83 unsigned NumVRegs = MF.getRegInfo().getNumVirtRegs();84 unsigned NumStackRegs = 0;85 // Start the numbering for locals after the arg regs86 unsigned CurReg = MFI.getParams().size();87 for (unsigned VRegIdx = 0; VRegIdx < NumVRegs; ++VRegIdx) {88 Register VReg = Register::index2VirtReg(VRegIdx);89 // Skip unused registers.90 if (MRI.use_empty(VReg))91 continue;92 // Handle stackified registers.93 if (MFI.isVRegStackified(VReg)) {94 LLVM_DEBUG(dbgs() << "VReg " << printReg(VReg) << " -> WAReg "95 << (INT32_MIN | NumStackRegs) << "\n");96 MFI.setWAReg(VReg, INT32_MIN | NumStackRegs++);97 continue;98 }99 if (MFI.getWAReg(VReg) == WebAssembly::UnusedReg) {100 LLVM_DEBUG(dbgs() << "VReg " << printReg(VReg) << " -> WAReg " << CurReg101 << "\n");102 MFI.setWAReg(VReg, CurReg++);103 }104 }105 106 return true;107}108