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to reflect the new license. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351636
103 lines
3.5 KiB
C++
103 lines
3.5 KiB
C++
//===-- WebAssemblyReplacePhysRegs.cpp - Replace phys regs with virt regs -===//
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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 that replaces physical registers with
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/// virtual registers.
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///
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/// LLVM expects certain physical registers, such as a stack pointer. However,
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/// WebAssembly doesn't actually have such physical registers. This pass is run
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/// once LLVM no longer needs these registers, and replaces them with virtual
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/// registers, so they can participate in register stackifying and coloring in
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/// the normal way.
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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 "llvm/CodeGen/MachineFunctionPass.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-replace-phys-regs"
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namespace {
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class WebAssemblyReplacePhysRegs final : public MachineFunctionPass {
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public:
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static char ID; // Pass identification, replacement for typeid
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WebAssemblyReplacePhysRegs() : MachineFunctionPass(ID) {}
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private:
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StringRef getPassName() const override {
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return "WebAssembly Replace Physical Registers";
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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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};
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} // end anonymous namespace
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char WebAssemblyReplacePhysRegs::ID = 0;
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INITIALIZE_PASS(WebAssemblyReplacePhysRegs, DEBUG_TYPE,
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"Replace physical registers with virtual registers", false,
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false)
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FunctionPass *llvm::createWebAssemblyReplacePhysRegs() {
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return new WebAssemblyReplacePhysRegs();
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}
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bool WebAssemblyReplacePhysRegs::runOnMachineFunction(MachineFunction &MF) {
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LLVM_DEBUG({
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dbgs() << "********** Replace Physical Registers **********\n"
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<< "********** Function: " << MF.getName() << '\n';
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});
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MachineRegisterInfo &MRI = MF.getRegInfo();
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const auto &TRI = *MF.getSubtarget<WebAssemblySubtarget>().getRegisterInfo();
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bool Changed = false;
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assert(!mustPreserveAnalysisID(LiveIntervalsID) &&
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"LiveIntervals shouldn't be active yet!");
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// We don't preserve SSA or liveness.
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MRI.leaveSSA();
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MRI.invalidateLiveness();
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for (unsigned PReg = WebAssembly::NoRegister + 1;
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PReg < WebAssembly::NUM_TARGET_REGS; ++PReg) {
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// Skip fake registers that are never used explicitly.
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if (PReg == WebAssembly::VALUE_STACK || PReg == WebAssembly::ARGUMENTS)
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continue;
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// Replace explicit uses of the physical register with a virtual register.
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const TargetRegisterClass *RC = TRI.getMinimalPhysRegClass(PReg);
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unsigned VReg = WebAssembly::NoRegister;
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for (auto I = MRI.reg_begin(PReg), E = MRI.reg_end(); I != E;) {
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MachineOperand &MO = *I++;
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if (!MO.isImplicit()) {
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if (VReg == WebAssembly::NoRegister)
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VReg = MRI.createVirtualRegister(RC);
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MO.setReg(VReg);
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if (MO.getParent()->isDebugValue())
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MO.setIsDebug();
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Changed = true;
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}
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}
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}
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return Changed;
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}
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