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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
98 lines
3.3 KiB
C++
98 lines
3.3 KiB
C++
//===-- WebAssemblyArgumentMove.cpp - Argument instruction moving ---------===//
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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 moves ARGUMENT instructions after ScheduleDAG scheduling.
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///
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/// Arguments are really live-in registers, however, since we use virtual
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/// registers and LLVM doesn't support live-in virtual registers, we're
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/// currently making do with ARGUMENT instructions which are placed at the top
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/// of the entry block. The trick is to get them to *stay* at the top of the
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/// entry block.
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///
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/// The ARGUMENTS physical register keeps these instructions pinned in place
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/// during liveness-aware CodeGen passes, however one thing which does not
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/// respect this is the ScheduleDAG scheduler. This pass is therefore run
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/// immediately after that.
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///
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/// This is all hopefully a temporary solution until we find a better solution
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/// for describing the live-in nature of arguments.
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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/CodeGen/MachineBlockFrequencyInfo.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-argument-move"
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namespace {
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class WebAssemblyArgumentMove final : public MachineFunctionPass {
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public:
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static char ID; // Pass identification, replacement for typeid
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WebAssemblyArgumentMove() : MachineFunctionPass(ID) {}
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StringRef getPassName() const override { return "WebAssembly Argument Move"; }
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.setPreservesCFG();
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AU.addPreserved<MachineBlockFrequencyInfo>();
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AU.addPreservedID(MachineDominatorsID);
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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 WebAssemblyArgumentMove::ID = 0;
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INITIALIZE_PASS(WebAssemblyArgumentMove, DEBUG_TYPE,
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"Move ARGUMENT instructions for WebAssembly", false, false)
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FunctionPass *llvm::createWebAssemblyArgumentMove() {
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return new WebAssemblyArgumentMove();
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}
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bool WebAssemblyArgumentMove::runOnMachineFunction(MachineFunction &MF) {
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LLVM_DEBUG({
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dbgs() << "********** Argument Move **********\n"
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<< "********** Function: " << MF.getName() << '\n';
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});
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bool Changed = false;
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MachineBasicBlock &EntryMBB = MF.front();
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MachineBasicBlock::iterator InsertPt = EntryMBB.end();
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// Look for the first NonArg instruction.
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for (MachineInstr &MI : EntryMBB) {
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if (!WebAssembly::isArgument(MI)) {
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InsertPt = MI;
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break;
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}
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}
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// Now move any argument instructions later in the block
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// to before our first NonArg instruction.
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for (MachineInstr &MI : llvm::make_range(InsertPt, EntryMBB.end())) {
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if (WebAssembly::isArgument(MI)) {
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EntryMBB.insert(InsertPt, MI.removeFromParent());
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Changed = true;
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}
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}
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return Changed;
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}
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