| //===-- WebAssemblyRegNumbering.cpp - Register Numbering ------------------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| /// |
| /// \file |
| /// This file implements a pass which assigns WebAssembly register |
| /// numbers for CodeGen virtual registers. |
| /// |
| //===----------------------------------------------------------------------===// |
| |
| #include "MCTargetDesc/WebAssemblyMCTargetDesc.h" |
| #include "Utils/WebAssemblyUtilities.h" |
| #include "WebAssembly.h" |
| #include "WebAssemblyMachineFunctionInfo.h" |
| #include "WebAssemblySubtarget.h" |
| #include "llvm/ADT/SCCIterator.h" |
| #include "llvm/CodeGen/MachineFrameInfo.h" |
| #include "llvm/CodeGen/MachineFunction.h" |
| #include "llvm/CodeGen/MachineInstrBuilder.h" |
| #include "llvm/CodeGen/MachineLoopInfo.h" |
| #include "llvm/CodeGen/MachineRegisterInfo.h" |
| #include "llvm/CodeGen/Passes.h" |
| #include "llvm/Support/Debug.h" |
| #include "llvm/Support/raw_ostream.h" |
| using namespace llvm; |
| |
| #define DEBUG_TYPE "wasm-reg-numbering" |
| |
| namespace { |
| class WebAssemblyRegNumbering final : public MachineFunctionPass { |
| StringRef getPassName() const override { |
| return "WebAssembly Register Numbering"; |
| } |
| |
| void getAnalysisUsage(AnalysisUsage &AU) const override { |
| AU.setPreservesCFG(); |
| MachineFunctionPass::getAnalysisUsage(AU); |
| } |
| |
| bool runOnMachineFunction(MachineFunction &MF) override; |
| |
| public: |
| static char ID; // Pass identification, replacement for typeid |
| WebAssemblyRegNumbering() : MachineFunctionPass(ID) {} |
| }; |
| } // end anonymous namespace |
| |
| char WebAssemblyRegNumbering::ID = 0; |
| INITIALIZE_PASS(WebAssemblyRegNumbering, DEBUG_TYPE, |
| "Assigns WebAssembly register numbers for virtual registers", |
| false, false) |
| |
| FunctionPass *llvm::createWebAssemblyRegNumbering() { |
| return new WebAssemblyRegNumbering(); |
| } |
| |
| bool WebAssemblyRegNumbering::runOnMachineFunction(MachineFunction &MF) { |
| LLVM_DEBUG(dbgs() << "********** Register Numbering **********\n" |
| "********** Function: " |
| << MF.getName() << '\n'); |
| |
| WebAssemblyFunctionInfo &MFI = *MF.getInfo<WebAssemblyFunctionInfo>(); |
| MachineRegisterInfo &MRI = MF.getRegInfo(); |
| |
| MFI.initWARegs(MRI); |
| |
| // WebAssembly argument registers are in the same index space as local |
| // variables. Assign the numbers for them first. |
| MachineBasicBlock &EntryMBB = MF.front(); |
| for (MachineInstr &MI : EntryMBB) { |
| if (!WebAssembly::isArgument(MI.getOpcode())) |
| break; |
| |
| int64_t Imm = MI.getOperand(1).getImm(); |
| LLVM_DEBUG(dbgs() << "Arg VReg " << MI.getOperand(0).getReg() |
| << " -> WAReg " << Imm << "\n"); |
| MFI.setWAReg(MI.getOperand(0).getReg(), Imm); |
| } |
| |
| // Then assign regular WebAssembly registers for all remaining used |
| // virtual registers. TODO: Consider sorting the registers by frequency of |
| // use, to maximize usage of small immediate fields. |
| unsigned NumVRegs = MF.getRegInfo().getNumVirtRegs(); |
| unsigned NumStackRegs = 0; |
| // Start the numbering for locals after the arg regs |
| unsigned CurReg = MFI.getParams().size(); |
| for (unsigned VRegIdx = 0; VRegIdx < NumVRegs; ++VRegIdx) { |
| unsigned VReg = Register::index2VirtReg(VRegIdx); |
| // Skip unused registers. |
| if (MRI.use_empty(VReg)) |
| continue; |
| // Handle stackified registers. |
| if (MFI.isVRegStackified(VReg)) { |
| LLVM_DEBUG(dbgs() << "VReg " << VReg << " -> WAReg " |
| << (INT32_MIN | NumStackRegs) << "\n"); |
| MFI.setWAReg(VReg, INT32_MIN | NumStackRegs++); |
| continue; |
| } |
| if (MFI.getWAReg(VReg) == WebAssemblyFunctionInfo::UnusedReg) { |
| LLVM_DEBUG(dbgs() << "VReg " << VReg << " -> WAReg " << CurReg << "\n"); |
| MFI.setWAReg(VReg, CurReg++); |
| } |
| } |
| |
| return true; |
| } |