111 lines
3.8 KiB
C++
111 lines
3.8 KiB
C++
//===-- lib/CodeGen/GlobalISel/GICombiner.cpp -----------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file constains common code to combine machine functions at generic
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// level.
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//===----------------------------------------------------------------------===//
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#include "llvm/CodeGen/GlobalISel/Combiner.h"
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#include "llvm/CodeGen/GlobalISel/CombinerInfo.h"
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#include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
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#include "llvm/CodeGen/MachineOptimizationRemarkEmitter.h"
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#include "llvm/CodeGen/GlobalISel/GISelWorkList.h"
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#include "llvm/ADT/PostOrderIterator.h"
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#include "llvm/CodeGen/GlobalISel/Utils.h"
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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#include "llvm/Support/Debug.h"
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#define DEBUG_TYPE "gi-combiner"
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using namespace llvm;
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namespace {
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/// This class acts as the glue the joins the CombinerHelper to the overall
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/// Combine algorithm. The CombinerHelper is intended to report the
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/// modifications it makes to the MIR to the CombinerChangeObserver and the
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/// observer subclass will act on these events. In this case, instruction
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/// erasure will cancel any future visits to the erased instruction and
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/// instruction creation will schedule that instruction for a future visit.
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/// Other Combiner implementations may require more complex behaviour from
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/// their CombinerChangeObserver subclass.
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class WorkListMaintainer : public CombinerChangeObserver {
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using WorkListTy = GISelWorkList<512>;
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WorkListTy &WorkList;
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public:
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WorkListMaintainer(WorkListTy &WorkList) : WorkList(WorkList) {}
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virtual ~WorkListMaintainer() {}
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void erasedInstr(MachineInstr &MI) override {
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LLVM_DEBUG(dbgs() << "Erased: "; MI.print(dbgs()); dbgs() << "\n");
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WorkList.remove(&MI);
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}
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void createdInstr(MachineInstr &MI) override {
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LLVM_DEBUG(dbgs() << "Created: "; MI.print(dbgs()); dbgs() << "\n");
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WorkList.insert(&MI);
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}
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};
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}
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Combiner::Combiner(CombinerInfo &Info, const TargetPassConfig *TPC)
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: CInfo(Info), TPC(TPC) {
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(void)this->TPC; // FIXME: Remove when used.
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}
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bool Combiner::combineMachineInstrs(MachineFunction &MF) {
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// If the ISel pipeline failed, do not bother running this pass.
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// FIXME: Should this be here or in individual combiner passes.
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if (MF.getProperties().hasProperty(
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MachineFunctionProperties::Property::FailedISel))
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return false;
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MRI = &MF.getRegInfo();
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Builder.setMF(MF);
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LLVM_DEBUG(dbgs() << "Generic MI Combiner for: " << MF.getName() << '\n');
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MachineOptimizationRemarkEmitter MORE(MF, /*MBFI=*/nullptr);
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bool MFChanged = false;
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bool Changed;
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do {
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// Collect all instructions. Do a post order traversal for basic blocks and
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// insert with list bottom up, so while we pop_back_val, we'll traverse top
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// down RPOT.
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Changed = false;
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GISelWorkList<512> WorkList;
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WorkListMaintainer Observer(WorkList);
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for (MachineBasicBlock *MBB : post_order(&MF)) {
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if (MBB->empty())
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continue;
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for (auto MII = MBB->rbegin(), MIE = MBB->rend(); MII != MIE;) {
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MachineInstr *CurMI = &*MII;
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++MII;
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// Erase dead insts before even adding to the list.
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if (isTriviallyDead(*CurMI, *MRI)) {
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LLVM_DEBUG(dbgs() << *CurMI << "Is dead; erasing.\n");
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CurMI->eraseFromParentAndMarkDBGValuesForRemoval();
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continue;
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}
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WorkList.insert(CurMI);
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}
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}
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// Main Loop. Process the instructions here.
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while (!WorkList.empty()) {
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MachineInstr *CurrInst = WorkList.pop_back_val();
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LLVM_DEBUG(dbgs() << "Try combining " << *CurrInst << "\n";);
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Changed |= CInfo.combine(Observer, *CurrInst, Builder);
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}
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MFChanged |= Changed;
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} while (Changed);
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return MFChanged;
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}
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