forked from OSchip/llvm-project
126 lines
3.5 KiB
C++
126 lines
3.5 KiB
C++
//===- bolt/Passes/AllocCombiner.cpp --------------------------------------===//
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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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// This file implements the AllocCombinerPass class.
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//
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//===----------------------------------------------------------------------===//
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#include "bolt/Passes/AllocCombiner.h"
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#define DEBUG_TYPE "alloccombiner"
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using namespace llvm;
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namespace opts {
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extern cl::opt<bolt::FrameOptimizationType> FrameOptimization;
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} // end namespace opts
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namespace llvm {
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namespace bolt {
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namespace {
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bool getStackAdjustmentSize(const BinaryContext &BC, const MCInst &Inst,
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int64_t &Adjustment) {
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return BC.MIB->evaluateSimple(Inst, Adjustment,
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std::make_pair(BC.MIB->getStackPointer(), 0LL),
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std::make_pair(0, 0LL));
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}
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bool isIndifferentToSP(const MCInst &Inst, const BinaryContext &BC) {
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if (BC.MIB->isCFI(Inst))
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return true;
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const MCInstrDesc II = BC.MII->get(Inst.getOpcode());
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if (BC.MIB->isTerminator(Inst) ||
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II.hasImplicitDefOfPhysReg(BC.MIB->getStackPointer(), BC.MRI.get()) ||
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II.hasImplicitUseOfPhysReg(BC.MIB->getStackPointer()))
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return false;
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for (int I = 0, E = MCPlus::getNumPrimeOperands(Inst); I != E; ++I) {
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const MCOperand &Operand = Inst.getOperand(I);
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if (Operand.isReg() && Operand.getReg() == BC.MIB->getStackPointer())
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return false;
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}
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return true;
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}
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bool shouldProcess(const BinaryFunction &Function) {
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return Function.isSimple() && Function.hasCFG() && !Function.isIgnored();
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}
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void runForAllWeCare(std::map<uint64_t, BinaryFunction> &BFs,
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std::function<void(BinaryFunction &)> Task) {
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for (auto &It : BFs) {
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BinaryFunction &Function = It.second;
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if (shouldProcess(Function))
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Task(Function);
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}
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}
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} // end anonymous namespace
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void AllocCombinerPass::combineAdjustments(BinaryFunction &BF) {
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BinaryContext &BC = BF.getBinaryContext();
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for (BinaryBasicBlock &BB : BF) {
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MCInst *Prev = nullptr;
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for (auto I = BB.rbegin(), E = BB.rend(); I != E; ++I) {
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MCInst &Inst = *I;
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if (isIndifferentToSP(Inst, BC))
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continue; // Skip updating Prev
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int64_t Adjustment = 0LL;
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if (!Prev || !BC.MIB->isStackAdjustment(Inst) ||
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!BC.MIB->isStackAdjustment(*Prev) ||
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!getStackAdjustmentSize(BC, *Prev, Adjustment)) {
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Prev = &Inst;
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continue;
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}
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LLVM_DEBUG({
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dbgs() << "At \"" << BF.getPrintName() << "\", combining: \n";
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Inst.dump();
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Prev->dump();
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dbgs() << "Adjustment: " << Adjustment << "\n";
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});
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if (BC.MIB->isSUB(Inst))
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Adjustment = -Adjustment;
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BC.MIB->addToImm(Inst, Adjustment, BC.Ctx.get());
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LLVM_DEBUG({
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dbgs() << "After adjustment:\n";
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Inst.dump();
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});
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BB.eraseInstruction(BB.findInstruction(Prev));
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++NumCombined;
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FuncsChanged.insert(&BF);
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Prev = &Inst;
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}
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}
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}
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void AllocCombinerPass::runOnFunctions(BinaryContext &BC) {
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if (opts::FrameOptimization == FOP_NONE)
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return;
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runForAllWeCare(BC.getBinaryFunctions(), [&](BinaryFunction &Function) {
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combineAdjustments(Function);
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});
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outs() << "BOLT-INFO: Allocation combiner: " << NumCombined
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<< " empty spaces coalesced.\n";
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}
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} // end namespace bolt
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} // end namespace llvm
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