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