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2196 lines
85 KiB
2196 lines
85 KiB
//===- ModuloSchedule.cpp - Software pipeline schedule expansion ----------===//
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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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#include "llvm/CodeGen/ModuloSchedule.h"
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#include "llvm/ADT/StringExtras.h"
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#include "llvm/Analysis/MemoryLocation.h"
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#include "llvm/CodeGen/LiveIntervals.h"
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#include "llvm/CodeGen/MachineInstrBuilder.h"
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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#include "llvm/InitializePasses.h"
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#include "llvm/MC/MCContext.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/raw_ostream.h"
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#define DEBUG_TYPE "pipeliner"
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using namespace llvm;
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void ModuloSchedule::print(raw_ostream &OS) {
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for (MachineInstr *MI : ScheduledInstrs)
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OS << "[stage " << getStage(MI) << " @" << getCycle(MI) << "c] " << *MI;
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}
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//===----------------------------------------------------------------------===//
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// ModuloScheduleExpander implementation
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//===----------------------------------------------------------------------===//
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/// Return the register values for the operands of a Phi instruction.
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/// This function assume the instruction is a Phi.
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static void getPhiRegs(MachineInstr &Phi, MachineBasicBlock *Loop,
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unsigned &InitVal, unsigned &LoopVal) {
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assert(Phi.isPHI() && "Expecting a Phi.");
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InitVal = 0;
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LoopVal = 0;
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for (unsigned i = 1, e = Phi.getNumOperands(); i != e; i += 2)
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if (Phi.getOperand(i + 1).getMBB() != Loop)
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InitVal = Phi.getOperand(i).getReg();
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else
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LoopVal = Phi.getOperand(i).getReg();
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assert(InitVal != 0 && LoopVal != 0 && "Unexpected Phi structure.");
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}
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/// Return the Phi register value that comes from the incoming block.
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static unsigned getInitPhiReg(MachineInstr &Phi, MachineBasicBlock *LoopBB) {
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for (unsigned i = 1, e = Phi.getNumOperands(); i != e; i += 2)
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if (Phi.getOperand(i + 1).getMBB() != LoopBB)
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return Phi.getOperand(i).getReg();
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return 0;
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}
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/// Return the Phi register value that comes the loop block.
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static unsigned getLoopPhiReg(MachineInstr &Phi, MachineBasicBlock *LoopBB) {
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for (unsigned i = 1, e = Phi.getNumOperands(); i != e; i += 2)
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if (Phi.getOperand(i + 1).getMBB() == LoopBB)
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return Phi.getOperand(i).getReg();
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return 0;
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}
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void ModuloScheduleExpander::expand() {
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BB = Schedule.getLoop()->getTopBlock();
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Preheader = *BB->pred_begin();
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if (Preheader == BB)
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Preheader = *std::next(BB->pred_begin());
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// Iterate over the definitions in each instruction, and compute the
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// stage difference for each use. Keep the maximum value.
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for (MachineInstr *MI : Schedule.getInstructions()) {
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int DefStage = Schedule.getStage(MI);
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for (unsigned i = 0, e = MI->getNumOperands(); i < e; ++i) {
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MachineOperand &Op = MI->getOperand(i);
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if (!Op.isReg() || !Op.isDef())
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continue;
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Register Reg = Op.getReg();
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unsigned MaxDiff = 0;
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bool PhiIsSwapped = false;
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for (MachineRegisterInfo::use_iterator UI = MRI.use_begin(Reg),
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EI = MRI.use_end();
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UI != EI; ++UI) {
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MachineOperand &UseOp = *UI;
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MachineInstr *UseMI = UseOp.getParent();
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int UseStage = Schedule.getStage(UseMI);
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unsigned Diff = 0;
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if (UseStage != -1 && UseStage >= DefStage)
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Diff = UseStage - DefStage;
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if (MI->isPHI()) {
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if (isLoopCarried(*MI))
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++Diff;
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else
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PhiIsSwapped = true;
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}
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MaxDiff = std::max(Diff, MaxDiff);
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}
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RegToStageDiff[Reg] = std::make_pair(MaxDiff, PhiIsSwapped);
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}
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}
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generatePipelinedLoop();
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}
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void ModuloScheduleExpander::generatePipelinedLoop() {
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LoopInfo = TII->analyzeLoopForPipelining(BB);
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assert(LoopInfo && "Must be able to analyze loop!");
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// Create a new basic block for the kernel and add it to the CFG.
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MachineBasicBlock *KernelBB = MF.CreateMachineBasicBlock(BB->getBasicBlock());
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unsigned MaxStageCount = Schedule.getNumStages() - 1;
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// Remember the registers that are used in different stages. The index is
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// the iteration, or stage, that the instruction is scheduled in. This is
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// a map between register names in the original block and the names created
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// in each stage of the pipelined loop.
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ValueMapTy *VRMap = new ValueMapTy[(MaxStageCount + 1) * 2];
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InstrMapTy InstrMap;
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SmallVector<MachineBasicBlock *, 4> PrologBBs;
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// Generate the prolog instructions that set up the pipeline.
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generateProlog(MaxStageCount, KernelBB, VRMap, PrologBBs);
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MF.insert(BB->getIterator(), KernelBB);
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// Rearrange the instructions to generate the new, pipelined loop,
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// and update register names as needed.
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for (MachineInstr *CI : Schedule.getInstructions()) {
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if (CI->isPHI())
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continue;
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unsigned StageNum = Schedule.getStage(CI);
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MachineInstr *NewMI = cloneInstr(CI, MaxStageCount, StageNum);
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updateInstruction(NewMI, false, MaxStageCount, StageNum, VRMap);
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KernelBB->push_back(NewMI);
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InstrMap[NewMI] = CI;
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}
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// Copy any terminator instructions to the new kernel, and update
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// names as needed.
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for (MachineBasicBlock::iterator I = BB->getFirstTerminator(),
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E = BB->instr_end();
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I != E; ++I) {
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MachineInstr *NewMI = MF.CloneMachineInstr(&*I);
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updateInstruction(NewMI, false, MaxStageCount, 0, VRMap);
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KernelBB->push_back(NewMI);
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InstrMap[NewMI] = &*I;
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}
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NewKernel = KernelBB;
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KernelBB->transferSuccessors(BB);
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KernelBB->replaceSuccessor(BB, KernelBB);
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generateExistingPhis(KernelBB, PrologBBs.back(), KernelBB, KernelBB, VRMap,
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InstrMap, MaxStageCount, MaxStageCount, false);
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generatePhis(KernelBB, PrologBBs.back(), KernelBB, KernelBB, VRMap, InstrMap,
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MaxStageCount, MaxStageCount, false);
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LLVM_DEBUG(dbgs() << "New block\n"; KernelBB->dump(););
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SmallVector<MachineBasicBlock *, 4> EpilogBBs;
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// Generate the epilog instructions to complete the pipeline.
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generateEpilog(MaxStageCount, KernelBB, VRMap, EpilogBBs, PrologBBs);
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// We need this step because the register allocation doesn't handle some
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// situations well, so we insert copies to help out.
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splitLifetimes(KernelBB, EpilogBBs);
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// Remove dead instructions due to loop induction variables.
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removeDeadInstructions(KernelBB, EpilogBBs);
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// Add branches between prolog and epilog blocks.
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addBranches(*Preheader, PrologBBs, KernelBB, EpilogBBs, VRMap);
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delete[] VRMap;
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}
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void ModuloScheduleExpander::cleanup() {
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// Remove the original loop since it's no longer referenced.
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for (auto &I : *BB)
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LIS.RemoveMachineInstrFromMaps(I);
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BB->clear();
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BB->eraseFromParent();
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}
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/// Generate the pipeline prolog code.
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void ModuloScheduleExpander::generateProlog(unsigned LastStage,
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MachineBasicBlock *KernelBB,
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ValueMapTy *VRMap,
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MBBVectorTy &PrologBBs) {
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MachineBasicBlock *PredBB = Preheader;
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InstrMapTy InstrMap;
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// Generate a basic block for each stage, not including the last stage,
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// which will be generated in the kernel. Each basic block may contain
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// instructions from multiple stages/iterations.
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for (unsigned i = 0; i < LastStage; ++i) {
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// Create and insert the prolog basic block prior to the original loop
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// basic block. The original loop is removed later.
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MachineBasicBlock *NewBB = MF.CreateMachineBasicBlock(BB->getBasicBlock());
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PrologBBs.push_back(NewBB);
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MF.insert(BB->getIterator(), NewBB);
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NewBB->transferSuccessors(PredBB);
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PredBB->addSuccessor(NewBB);
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PredBB = NewBB;
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// Generate instructions for each appropriate stage. Process instructions
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// in original program order.
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for (int StageNum = i; StageNum >= 0; --StageNum) {
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for (MachineBasicBlock::iterator BBI = BB->instr_begin(),
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BBE = BB->getFirstTerminator();
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BBI != BBE; ++BBI) {
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if (Schedule.getStage(&*BBI) == StageNum) {
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if (BBI->isPHI())
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continue;
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MachineInstr *NewMI =
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cloneAndChangeInstr(&*BBI, i, (unsigned)StageNum);
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updateInstruction(NewMI, false, i, (unsigned)StageNum, VRMap);
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NewBB->push_back(NewMI);
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InstrMap[NewMI] = &*BBI;
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}
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}
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}
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rewritePhiValues(NewBB, i, VRMap, InstrMap);
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LLVM_DEBUG({
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dbgs() << "prolog:\n";
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NewBB->dump();
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});
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}
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PredBB->replaceSuccessor(BB, KernelBB);
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// Check if we need to remove the branch from the preheader to the original
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// loop, and replace it with a branch to the new loop.
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unsigned numBranches = TII->removeBranch(*Preheader);
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if (numBranches) {
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SmallVector<MachineOperand, 0> Cond;
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TII->insertBranch(*Preheader, PrologBBs[0], nullptr, Cond, DebugLoc());
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}
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}
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/// Generate the pipeline epilog code. The epilog code finishes the iterations
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/// that were started in either the prolog or the kernel. We create a basic
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/// block for each stage that needs to complete.
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void ModuloScheduleExpander::generateEpilog(unsigned LastStage,
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MachineBasicBlock *KernelBB,
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ValueMapTy *VRMap,
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MBBVectorTy &EpilogBBs,
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MBBVectorTy &PrologBBs) {
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// We need to change the branch from the kernel to the first epilog block, so
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// this call to analyze branch uses the kernel rather than the original BB.
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MachineBasicBlock *TBB = nullptr, *FBB = nullptr;
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SmallVector<MachineOperand, 4> Cond;
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bool checkBranch = TII->analyzeBranch(*KernelBB, TBB, FBB, Cond);
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assert(!checkBranch && "generateEpilog must be able to analyze the branch");
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if (checkBranch)
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return;
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MachineBasicBlock::succ_iterator LoopExitI = KernelBB->succ_begin();
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if (*LoopExitI == KernelBB)
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++LoopExitI;
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assert(LoopExitI != KernelBB->succ_end() && "Expecting a successor");
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MachineBasicBlock *LoopExitBB = *LoopExitI;
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MachineBasicBlock *PredBB = KernelBB;
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MachineBasicBlock *EpilogStart = LoopExitBB;
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InstrMapTy InstrMap;
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// Generate a basic block for each stage, not including the last stage,
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// which was generated for the kernel. Each basic block may contain
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// instructions from multiple stages/iterations.
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int EpilogStage = LastStage + 1;
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for (unsigned i = LastStage; i >= 1; --i, ++EpilogStage) {
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MachineBasicBlock *NewBB = MF.CreateMachineBasicBlock();
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EpilogBBs.push_back(NewBB);
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MF.insert(BB->getIterator(), NewBB);
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PredBB->replaceSuccessor(LoopExitBB, NewBB);
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NewBB->addSuccessor(LoopExitBB);
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if (EpilogStart == LoopExitBB)
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EpilogStart = NewBB;
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// Add instructions to the epilog depending on the current block.
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// Process instructions in original program order.
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for (unsigned StageNum = i; StageNum <= LastStage; ++StageNum) {
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for (auto &BBI : *BB) {
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if (BBI.isPHI())
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continue;
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MachineInstr *In = &BBI;
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if ((unsigned)Schedule.getStage(In) == StageNum) {
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// Instructions with memoperands in the epilog are updated with
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// conservative values.
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MachineInstr *NewMI = cloneInstr(In, UINT_MAX, 0);
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updateInstruction(NewMI, i == 1, EpilogStage, 0, VRMap);
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NewBB->push_back(NewMI);
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InstrMap[NewMI] = In;
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}
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}
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}
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generateExistingPhis(NewBB, PrologBBs[i - 1], PredBB, KernelBB, VRMap,
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InstrMap, LastStage, EpilogStage, i == 1);
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generatePhis(NewBB, PrologBBs[i - 1], PredBB, KernelBB, VRMap, InstrMap,
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LastStage, EpilogStage, i == 1);
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PredBB = NewBB;
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LLVM_DEBUG({
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dbgs() << "epilog:\n";
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NewBB->dump();
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});
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}
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// Fix any Phi nodes in the loop exit block.
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LoopExitBB->replacePhiUsesWith(BB, PredBB);
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// Create a branch to the new epilog from the kernel.
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// Remove the original branch and add a new branch to the epilog.
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TII->removeBranch(*KernelBB);
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TII->insertBranch(*KernelBB, KernelBB, EpilogStart, Cond, DebugLoc());
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// Add a branch to the loop exit.
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if (EpilogBBs.size() > 0) {
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MachineBasicBlock *LastEpilogBB = EpilogBBs.back();
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SmallVector<MachineOperand, 4> Cond1;
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TII->insertBranch(*LastEpilogBB, LoopExitBB, nullptr, Cond1, DebugLoc());
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}
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}
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/// Replace all uses of FromReg that appear outside the specified
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/// basic block with ToReg.
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static void replaceRegUsesAfterLoop(unsigned FromReg, unsigned ToReg,
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MachineBasicBlock *MBB,
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MachineRegisterInfo &MRI,
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LiveIntervals &LIS) {
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for (MachineRegisterInfo::use_iterator I = MRI.use_begin(FromReg),
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E = MRI.use_end();
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I != E;) {
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MachineOperand &O = *I;
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++I;
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if (O.getParent()->getParent() != MBB)
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O.setReg(ToReg);
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}
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if (!LIS.hasInterval(ToReg))
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LIS.createEmptyInterval(ToReg);
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}
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/// Return true if the register has a use that occurs outside the
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/// specified loop.
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static bool hasUseAfterLoop(unsigned Reg, MachineBasicBlock *BB,
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MachineRegisterInfo &MRI) {
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for (MachineRegisterInfo::use_iterator I = MRI.use_begin(Reg),
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E = MRI.use_end();
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I != E; ++I)
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if (I->getParent()->getParent() != BB)
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return true;
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return false;
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}
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/// Generate Phis for the specific block in the generated pipelined code.
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/// This function looks at the Phis from the original code to guide the
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/// creation of new Phis.
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void ModuloScheduleExpander::generateExistingPhis(
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MachineBasicBlock *NewBB, MachineBasicBlock *BB1, MachineBasicBlock *BB2,
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MachineBasicBlock *KernelBB, ValueMapTy *VRMap, InstrMapTy &InstrMap,
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unsigned LastStageNum, unsigned CurStageNum, bool IsLast) {
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// Compute the stage number for the initial value of the Phi, which
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// comes from the prolog. The prolog to use depends on to which kernel/
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// epilog that we're adding the Phi.
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unsigned PrologStage = 0;
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unsigned PrevStage = 0;
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bool InKernel = (LastStageNum == CurStageNum);
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if (InKernel) {
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PrologStage = LastStageNum - 1;
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PrevStage = CurStageNum;
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} else {
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PrologStage = LastStageNum - (CurStageNum - LastStageNum);
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PrevStage = LastStageNum + (CurStageNum - LastStageNum) - 1;
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}
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for (MachineBasicBlock::iterator BBI = BB->instr_begin(),
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BBE = BB->getFirstNonPHI();
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BBI != BBE; ++BBI) {
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Register Def = BBI->getOperand(0).getReg();
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unsigned InitVal = 0;
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unsigned LoopVal = 0;
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getPhiRegs(*BBI, BB, InitVal, LoopVal);
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unsigned PhiOp1 = 0;
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// The Phi value from the loop body typically is defined in the loop, but
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// not always. So, we need to check if the value is defined in the loop.
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unsigned PhiOp2 = LoopVal;
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if (VRMap[LastStageNum].count(LoopVal))
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PhiOp2 = VRMap[LastStageNum][LoopVal];
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int StageScheduled = Schedule.getStage(&*BBI);
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int LoopValStage = Schedule.getStage(MRI.getVRegDef(LoopVal));
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unsigned NumStages = getStagesForReg(Def, CurStageNum);
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if (NumStages == 0) {
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// We don't need to generate a Phi anymore, but we need to rename any uses
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// of the Phi value.
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unsigned NewReg = VRMap[PrevStage][LoopVal];
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rewriteScheduledInstr(NewBB, InstrMap, CurStageNum, 0, &*BBI, Def,
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InitVal, NewReg);
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if (VRMap[CurStageNum].count(LoopVal))
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VRMap[CurStageNum][Def] = VRMap[CurStageNum][LoopVal];
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}
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// Adjust the number of Phis needed depending on the number of prologs left,
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// and the distance from where the Phi is first scheduled. The number of
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// Phis cannot exceed the number of prolog stages. Each stage can
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// potentially define two values.
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unsigned MaxPhis = PrologStage + 2;
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if (!InKernel && (int)PrologStage <= LoopValStage)
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MaxPhis = std::max((int)MaxPhis - (int)LoopValStage, 1);
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unsigned NumPhis = std::min(NumStages, MaxPhis);
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unsigned NewReg = 0;
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unsigned AccessStage = (LoopValStage != -1) ? LoopValStage : StageScheduled;
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// In the epilog, we may need to look back one stage to get the correct
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// Phi name, because the epilog and prolog blocks execute the same stage.
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// The correct name is from the previous block only when the Phi has
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// been completely scheduled prior to the epilog, and Phi value is not
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// needed in multiple stages.
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int StageDiff = 0;
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if (!InKernel && StageScheduled >= LoopValStage && AccessStage == 0 &&
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NumPhis == 1)
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StageDiff = 1;
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// Adjust the computations below when the phi and the loop definition
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// are scheduled in different stages.
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if (InKernel && LoopValStage != -1 && StageScheduled > LoopValStage)
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StageDiff = StageScheduled - LoopValStage;
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for (unsigned np = 0; np < NumPhis; ++np) {
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// If the Phi hasn't been scheduled, then use the initial Phi operand
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// value. Otherwise, use the scheduled version of the instruction. This
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// is a little complicated when a Phi references another Phi.
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if (np > PrologStage || StageScheduled >= (int)LastStageNum)
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PhiOp1 = InitVal;
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// Check if the Phi has already been scheduled in a prolog stage.
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else if (PrologStage >= AccessStage + StageDiff + np &&
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VRMap[PrologStage - StageDiff - np].count(LoopVal) != 0)
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PhiOp1 = VRMap[PrologStage - StageDiff - np][LoopVal];
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// Check if the Phi has already been scheduled, but the loop instruction
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// is either another Phi, or doesn't occur in the loop.
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else if (PrologStage >= AccessStage + StageDiff + np) {
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// If the Phi references another Phi, we need to examine the other
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// Phi to get the correct value.
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PhiOp1 = LoopVal;
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MachineInstr *InstOp1 = MRI.getVRegDef(PhiOp1);
|
|
int Indirects = 1;
|
|
while (InstOp1 && InstOp1->isPHI() && InstOp1->getParent() == BB) {
|
|
int PhiStage = Schedule.getStage(InstOp1);
|
|
if ((int)(PrologStage - StageDiff - np) < PhiStage + Indirects)
|
|
PhiOp1 = getInitPhiReg(*InstOp1, BB);
|
|
else
|
|
PhiOp1 = getLoopPhiReg(*InstOp1, BB);
|
|
InstOp1 = MRI.getVRegDef(PhiOp1);
|
|
int PhiOpStage = Schedule.getStage(InstOp1);
|
|
int StageAdj = (PhiOpStage != -1 ? PhiStage - PhiOpStage : 0);
|
|
if (PhiOpStage != -1 && PrologStage - StageAdj >= Indirects + np &&
|
|
VRMap[PrologStage - StageAdj - Indirects - np].count(PhiOp1)) {
|
|
PhiOp1 = VRMap[PrologStage - StageAdj - Indirects - np][PhiOp1];
|
|
break;
|
|
}
|
|
++Indirects;
|
|
}
|
|
} else
|
|
PhiOp1 = InitVal;
|
|
// If this references a generated Phi in the kernel, get the Phi operand
|
|
// from the incoming block.
|
|
if (MachineInstr *InstOp1 = MRI.getVRegDef(PhiOp1))
|
|
if (InstOp1->isPHI() && InstOp1->getParent() == KernelBB)
|
|
PhiOp1 = getInitPhiReg(*InstOp1, KernelBB);
|
|
|
|
MachineInstr *PhiInst = MRI.getVRegDef(LoopVal);
|
|
bool LoopDefIsPhi = PhiInst && PhiInst->isPHI();
|
|
// In the epilog, a map lookup is needed to get the value from the kernel,
|
|
// or previous epilog block. How is does this depends on if the
|
|
// instruction is scheduled in the previous block.
|
|
if (!InKernel) {
|
|
int StageDiffAdj = 0;
|
|
if (LoopValStage != -1 && StageScheduled > LoopValStage)
|
|
StageDiffAdj = StageScheduled - LoopValStage;
|
|
// Use the loop value defined in the kernel, unless the kernel
|
|
// contains the last definition of the Phi.
|
|
if (np == 0 && PrevStage == LastStageNum &&
|
|
(StageScheduled != 0 || LoopValStage != 0) &&
|
|
VRMap[PrevStage - StageDiffAdj].count(LoopVal))
|
|
PhiOp2 = VRMap[PrevStage - StageDiffAdj][LoopVal];
|
|
// Use the value defined by the Phi. We add one because we switch
|
|
// from looking at the loop value to the Phi definition.
|
|
else if (np > 0 && PrevStage == LastStageNum &&
|
|
VRMap[PrevStage - np + 1].count(Def))
|
|
PhiOp2 = VRMap[PrevStage - np + 1][Def];
|
|
// Use the loop value defined in the kernel.
|
|
else if (static_cast<unsigned>(LoopValStage) > PrologStage + 1 &&
|
|
VRMap[PrevStage - StageDiffAdj - np].count(LoopVal))
|
|
PhiOp2 = VRMap[PrevStage - StageDiffAdj - np][LoopVal];
|
|
// Use the value defined by the Phi, unless we're generating the first
|
|
// epilog and the Phi refers to a Phi in a different stage.
|
|
else if (VRMap[PrevStage - np].count(Def) &&
|
|
(!LoopDefIsPhi || (PrevStage != LastStageNum) ||
|
|
(LoopValStage == StageScheduled)))
|
|
PhiOp2 = VRMap[PrevStage - np][Def];
|
|
}
|
|
|
|
// Check if we can reuse an existing Phi. This occurs when a Phi
|
|
// references another Phi, and the other Phi is scheduled in an
|
|
// earlier stage. We can try to reuse an existing Phi up until the last
|
|
// stage of the current Phi.
|
|
if (LoopDefIsPhi) {
|
|
if (static_cast<int>(PrologStage - np) >= StageScheduled) {
|
|
int LVNumStages = getStagesForPhi(LoopVal);
|
|
int StageDiff = (StageScheduled - LoopValStage);
|
|
LVNumStages -= StageDiff;
|
|
// Make sure the loop value Phi has been processed already.
|
|
if (LVNumStages > (int)np && VRMap[CurStageNum].count(LoopVal)) {
|
|
NewReg = PhiOp2;
|
|
unsigned ReuseStage = CurStageNum;
|
|
if (isLoopCarried(*PhiInst))
|
|
ReuseStage -= LVNumStages;
|
|
// Check if the Phi to reuse has been generated yet. If not, then
|
|
// there is nothing to reuse.
|
|
if (VRMap[ReuseStage - np].count(LoopVal)) {
|
|
NewReg = VRMap[ReuseStage - np][LoopVal];
|
|
|
|
rewriteScheduledInstr(NewBB, InstrMap, CurStageNum, np, &*BBI,
|
|
Def, NewReg);
|
|
// Update the map with the new Phi name.
|
|
VRMap[CurStageNum - np][Def] = NewReg;
|
|
PhiOp2 = NewReg;
|
|
if (VRMap[LastStageNum - np - 1].count(LoopVal))
|
|
PhiOp2 = VRMap[LastStageNum - np - 1][LoopVal];
|
|
|
|
if (IsLast && np == NumPhis - 1)
|
|
replaceRegUsesAfterLoop(Def, NewReg, BB, MRI, LIS);
|
|
continue;
|
|
}
|
|
}
|
|
}
|
|
if (InKernel && StageDiff > 0 &&
|
|
VRMap[CurStageNum - StageDiff - np].count(LoopVal))
|
|
PhiOp2 = VRMap[CurStageNum - StageDiff - np][LoopVal];
|
|
}
|
|
|
|
const TargetRegisterClass *RC = MRI.getRegClass(Def);
|
|
NewReg = MRI.createVirtualRegister(RC);
|
|
|
|
MachineInstrBuilder NewPhi =
|
|
BuildMI(*NewBB, NewBB->getFirstNonPHI(), DebugLoc(),
|
|
TII->get(TargetOpcode::PHI), NewReg);
|
|
NewPhi.addReg(PhiOp1).addMBB(BB1);
|
|
NewPhi.addReg(PhiOp2).addMBB(BB2);
|
|
if (np == 0)
|
|
InstrMap[NewPhi] = &*BBI;
|
|
|
|
// We define the Phis after creating the new pipelined code, so
|
|
// we need to rename the Phi values in scheduled instructions.
|
|
|
|
unsigned PrevReg = 0;
|
|
if (InKernel && VRMap[PrevStage - np].count(LoopVal))
|
|
PrevReg = VRMap[PrevStage - np][LoopVal];
|
|
rewriteScheduledInstr(NewBB, InstrMap, CurStageNum, np, &*BBI, Def,
|
|
NewReg, PrevReg);
|
|
// If the Phi has been scheduled, use the new name for rewriting.
|
|
if (VRMap[CurStageNum - np].count(Def)) {
|
|
unsigned R = VRMap[CurStageNum - np][Def];
|
|
rewriteScheduledInstr(NewBB, InstrMap, CurStageNum, np, &*BBI, R,
|
|
NewReg);
|
|
}
|
|
|
|
// Check if we need to rename any uses that occurs after the loop. The
|
|
// register to replace depends on whether the Phi is scheduled in the
|
|
// epilog.
|
|
if (IsLast && np == NumPhis - 1)
|
|
replaceRegUsesAfterLoop(Def, NewReg, BB, MRI, LIS);
|
|
|
|
// In the kernel, a dependent Phi uses the value from this Phi.
|
|
if (InKernel)
|
|
PhiOp2 = NewReg;
|
|
|
|
// Update the map with the new Phi name.
|
|
VRMap[CurStageNum - np][Def] = NewReg;
|
|
}
|
|
|
|
while (NumPhis++ < NumStages) {
|
|
rewriteScheduledInstr(NewBB, InstrMap, CurStageNum, NumPhis, &*BBI, Def,
|
|
NewReg, 0);
|
|
}
|
|
|
|
// Check if we need to rename a Phi that has been eliminated due to
|
|
// scheduling.
|
|
if (NumStages == 0 && IsLast && VRMap[CurStageNum].count(LoopVal))
|
|
replaceRegUsesAfterLoop(Def, VRMap[CurStageNum][LoopVal], BB, MRI, LIS);
|
|
}
|
|
}
|
|
|
|
/// Generate Phis for the specified block in the generated pipelined code.
|
|
/// These are new Phis needed because the definition is scheduled after the
|
|
/// use in the pipelined sequence.
|
|
void ModuloScheduleExpander::generatePhis(
|
|
MachineBasicBlock *NewBB, MachineBasicBlock *BB1, MachineBasicBlock *BB2,
|
|
MachineBasicBlock *KernelBB, ValueMapTy *VRMap, InstrMapTy &InstrMap,
|
|
unsigned LastStageNum, unsigned CurStageNum, bool IsLast) {
|
|
// Compute the stage number that contains the initial Phi value, and
|
|
// the Phi from the previous stage.
|
|
unsigned PrologStage = 0;
|
|
unsigned PrevStage = 0;
|
|
unsigned StageDiff = CurStageNum - LastStageNum;
|
|
bool InKernel = (StageDiff == 0);
|
|
if (InKernel) {
|
|
PrologStage = LastStageNum - 1;
|
|
PrevStage = CurStageNum;
|
|
} else {
|
|
PrologStage = LastStageNum - StageDiff;
|
|
PrevStage = LastStageNum + StageDiff - 1;
|
|
}
|
|
|
|
for (MachineBasicBlock::iterator BBI = BB->getFirstNonPHI(),
|
|
BBE = BB->instr_end();
|
|
BBI != BBE; ++BBI) {
|
|
for (unsigned i = 0, e = BBI->getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = BBI->getOperand(i);
|
|
if (!MO.isReg() || !MO.isDef() ||
|
|
!Register::isVirtualRegister(MO.getReg()))
|
|
continue;
|
|
|
|
int StageScheduled = Schedule.getStage(&*BBI);
|
|
assert(StageScheduled != -1 && "Expecting scheduled instruction.");
|
|
Register Def = MO.getReg();
|
|
unsigned NumPhis = getStagesForReg(Def, CurStageNum);
|
|
// An instruction scheduled in stage 0 and is used after the loop
|
|
// requires a phi in the epilog for the last definition from either
|
|
// the kernel or prolog.
|
|
if (!InKernel && NumPhis == 0 && StageScheduled == 0 &&
|
|
hasUseAfterLoop(Def, BB, MRI))
|
|
NumPhis = 1;
|
|
if (!InKernel && (unsigned)StageScheduled > PrologStage)
|
|
continue;
|
|
|
|
unsigned PhiOp2 = VRMap[PrevStage][Def];
|
|
if (MachineInstr *InstOp2 = MRI.getVRegDef(PhiOp2))
|
|
if (InstOp2->isPHI() && InstOp2->getParent() == NewBB)
|
|
PhiOp2 = getLoopPhiReg(*InstOp2, BB2);
|
|
// The number of Phis can't exceed the number of prolog stages. The
|
|
// prolog stage number is zero based.
|
|
if (NumPhis > PrologStage + 1 - StageScheduled)
|
|
NumPhis = PrologStage + 1 - StageScheduled;
|
|
for (unsigned np = 0; np < NumPhis; ++np) {
|
|
unsigned PhiOp1 = VRMap[PrologStage][Def];
|
|
if (np <= PrologStage)
|
|
PhiOp1 = VRMap[PrologStage - np][Def];
|
|
if (MachineInstr *InstOp1 = MRI.getVRegDef(PhiOp1)) {
|
|
if (InstOp1->isPHI() && InstOp1->getParent() == KernelBB)
|
|
PhiOp1 = getInitPhiReg(*InstOp1, KernelBB);
|
|
if (InstOp1->isPHI() && InstOp1->getParent() == NewBB)
|
|
PhiOp1 = getInitPhiReg(*InstOp1, NewBB);
|
|
}
|
|
if (!InKernel)
|
|
PhiOp2 = VRMap[PrevStage - np][Def];
|
|
|
|
const TargetRegisterClass *RC = MRI.getRegClass(Def);
|
|
Register NewReg = MRI.createVirtualRegister(RC);
|
|
|
|
MachineInstrBuilder NewPhi =
|
|
BuildMI(*NewBB, NewBB->getFirstNonPHI(), DebugLoc(),
|
|
TII->get(TargetOpcode::PHI), NewReg);
|
|
NewPhi.addReg(PhiOp1).addMBB(BB1);
|
|
NewPhi.addReg(PhiOp2).addMBB(BB2);
|
|
if (np == 0)
|
|
InstrMap[NewPhi] = &*BBI;
|
|
|
|
// Rewrite uses and update the map. The actions depend upon whether
|
|
// we generating code for the kernel or epilog blocks.
|
|
if (InKernel) {
|
|
rewriteScheduledInstr(NewBB, InstrMap, CurStageNum, np, &*BBI, PhiOp1,
|
|
NewReg);
|
|
rewriteScheduledInstr(NewBB, InstrMap, CurStageNum, np, &*BBI, PhiOp2,
|
|
NewReg);
|
|
|
|
PhiOp2 = NewReg;
|
|
VRMap[PrevStage - np - 1][Def] = NewReg;
|
|
} else {
|
|
VRMap[CurStageNum - np][Def] = NewReg;
|
|
if (np == NumPhis - 1)
|
|
rewriteScheduledInstr(NewBB, InstrMap, CurStageNum, np, &*BBI, Def,
|
|
NewReg);
|
|
}
|
|
if (IsLast && np == NumPhis - 1)
|
|
replaceRegUsesAfterLoop(Def, NewReg, BB, MRI, LIS);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Remove instructions that generate values with no uses.
|
|
/// Typically, these are induction variable operations that generate values
|
|
/// used in the loop itself. A dead instruction has a definition with
|
|
/// no uses, or uses that occur in the original loop only.
|
|
void ModuloScheduleExpander::removeDeadInstructions(MachineBasicBlock *KernelBB,
|
|
MBBVectorTy &EpilogBBs) {
|
|
// For each epilog block, check that the value defined by each instruction
|
|
// is used. If not, delete it.
|
|
for (MBBVectorTy::reverse_iterator MBB = EpilogBBs.rbegin(),
|
|
MBE = EpilogBBs.rend();
|
|
MBB != MBE; ++MBB)
|
|
for (MachineBasicBlock::reverse_instr_iterator MI = (*MBB)->instr_rbegin(),
|
|
ME = (*MBB)->instr_rend();
|
|
MI != ME;) {
|
|
// From DeadMachineInstructionElem. Don't delete inline assembly.
|
|
if (MI->isInlineAsm()) {
|
|
++MI;
|
|
continue;
|
|
}
|
|
bool SawStore = false;
|
|
// Check if it's safe to remove the instruction due to side effects.
|
|
// We can, and want to, remove Phis here.
|
|
if (!MI->isSafeToMove(nullptr, SawStore) && !MI->isPHI()) {
|
|
++MI;
|
|
continue;
|
|
}
|
|
bool used = true;
|
|
for (MachineInstr::mop_iterator MOI = MI->operands_begin(),
|
|
MOE = MI->operands_end();
|
|
MOI != MOE; ++MOI) {
|
|
if (!MOI->isReg() || !MOI->isDef())
|
|
continue;
|
|
Register reg = MOI->getReg();
|
|
// Assume physical registers are used, unless they are marked dead.
|
|
if (Register::isPhysicalRegister(reg)) {
|
|
used = !MOI->isDead();
|
|
if (used)
|
|
break;
|
|
continue;
|
|
}
|
|
unsigned realUses = 0;
|
|
for (MachineRegisterInfo::use_iterator UI = MRI.use_begin(reg),
|
|
EI = MRI.use_end();
|
|
UI != EI; ++UI) {
|
|
// Check if there are any uses that occur only in the original
|
|
// loop. If so, that's not a real use.
|
|
if (UI->getParent()->getParent() != BB) {
|
|
realUses++;
|
|
used = true;
|
|
break;
|
|
}
|
|
}
|
|
if (realUses > 0)
|
|
break;
|
|
used = false;
|
|
}
|
|
if (!used) {
|
|
LIS.RemoveMachineInstrFromMaps(*MI);
|
|
MI++->eraseFromParent();
|
|
continue;
|
|
}
|
|
++MI;
|
|
}
|
|
// In the kernel block, check if we can remove a Phi that generates a value
|
|
// used in an instruction removed in the epilog block.
|
|
for (MachineBasicBlock::iterator BBI = KernelBB->instr_begin(),
|
|
BBE = KernelBB->getFirstNonPHI();
|
|
BBI != BBE;) {
|
|
MachineInstr *MI = &*BBI;
|
|
++BBI;
|
|
Register reg = MI->getOperand(0).getReg();
|
|
if (MRI.use_begin(reg) == MRI.use_end()) {
|
|
LIS.RemoveMachineInstrFromMaps(*MI);
|
|
MI->eraseFromParent();
|
|
}
|
|
}
|
|
}
|
|
|
|
/// For loop carried definitions, we split the lifetime of a virtual register
|
|
/// that has uses past the definition in the next iteration. A copy with a new
|
|
/// virtual register is inserted before the definition, which helps with
|
|
/// generating a better register assignment.
|
|
///
|
|
/// v1 = phi(a, v2) v1 = phi(a, v2)
|
|
/// v2 = phi(b, v3) v2 = phi(b, v3)
|
|
/// v3 = .. v4 = copy v1
|
|
/// .. = V1 v3 = ..
|
|
/// .. = v4
|
|
void ModuloScheduleExpander::splitLifetimes(MachineBasicBlock *KernelBB,
|
|
MBBVectorTy &EpilogBBs) {
|
|
const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
|
|
for (auto &PHI : KernelBB->phis()) {
|
|
Register Def = PHI.getOperand(0).getReg();
|
|
// Check for any Phi definition that used as an operand of another Phi
|
|
// in the same block.
|
|
for (MachineRegisterInfo::use_instr_iterator I = MRI.use_instr_begin(Def),
|
|
E = MRI.use_instr_end();
|
|
I != E; ++I) {
|
|
if (I->isPHI() && I->getParent() == KernelBB) {
|
|
// Get the loop carried definition.
|
|
unsigned LCDef = getLoopPhiReg(PHI, KernelBB);
|
|
if (!LCDef)
|
|
continue;
|
|
MachineInstr *MI = MRI.getVRegDef(LCDef);
|
|
if (!MI || MI->getParent() != KernelBB || MI->isPHI())
|
|
continue;
|
|
// Search through the rest of the block looking for uses of the Phi
|
|
// definition. If one occurs, then split the lifetime.
|
|
unsigned SplitReg = 0;
|
|
for (auto &BBJ : make_range(MachineBasicBlock::instr_iterator(MI),
|
|
KernelBB->instr_end()))
|
|
if (BBJ.readsRegister(Def)) {
|
|
// We split the lifetime when we find the first use.
|
|
if (SplitReg == 0) {
|
|
SplitReg = MRI.createVirtualRegister(MRI.getRegClass(Def));
|
|
BuildMI(*KernelBB, MI, MI->getDebugLoc(),
|
|
TII->get(TargetOpcode::COPY), SplitReg)
|
|
.addReg(Def);
|
|
}
|
|
BBJ.substituteRegister(Def, SplitReg, 0, *TRI);
|
|
}
|
|
if (!SplitReg)
|
|
continue;
|
|
// Search through each of the epilog blocks for any uses to be renamed.
|
|
for (auto &Epilog : EpilogBBs)
|
|
for (auto &I : *Epilog)
|
|
if (I.readsRegister(Def))
|
|
I.substituteRegister(Def, SplitReg, 0, *TRI);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Remove the incoming block from the Phis in a basic block.
|
|
static void removePhis(MachineBasicBlock *BB, MachineBasicBlock *Incoming) {
|
|
for (MachineInstr &MI : *BB) {
|
|
if (!MI.isPHI())
|
|
break;
|
|
for (unsigned i = 1, e = MI.getNumOperands(); i != e; i += 2)
|
|
if (MI.getOperand(i + 1).getMBB() == Incoming) {
|
|
MI.RemoveOperand(i + 1);
|
|
MI.RemoveOperand(i);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Create branches from each prolog basic block to the appropriate epilog
|
|
/// block. These edges are needed if the loop ends before reaching the
|
|
/// kernel.
|
|
void ModuloScheduleExpander::addBranches(MachineBasicBlock &PreheaderBB,
|
|
MBBVectorTy &PrologBBs,
|
|
MachineBasicBlock *KernelBB,
|
|
MBBVectorTy &EpilogBBs,
|
|
ValueMapTy *VRMap) {
|
|
assert(PrologBBs.size() == EpilogBBs.size() && "Prolog/Epilog mismatch");
|
|
MachineBasicBlock *LastPro = KernelBB;
|
|
MachineBasicBlock *LastEpi = KernelBB;
|
|
|
|
// Start from the blocks connected to the kernel and work "out"
|
|
// to the first prolog and the last epilog blocks.
|
|
SmallVector<MachineInstr *, 4> PrevInsts;
|
|
unsigned MaxIter = PrologBBs.size() - 1;
|
|
for (unsigned i = 0, j = MaxIter; i <= MaxIter; ++i, --j) {
|
|
// Add branches to the prolog that go to the corresponding
|
|
// epilog, and the fall-thru prolog/kernel block.
|
|
MachineBasicBlock *Prolog = PrologBBs[j];
|
|
MachineBasicBlock *Epilog = EpilogBBs[i];
|
|
|
|
SmallVector<MachineOperand, 4> Cond;
|
|
Optional<bool> StaticallyGreater =
|
|
LoopInfo->createTripCountGreaterCondition(j + 1, *Prolog, Cond);
|
|
unsigned numAdded = 0;
|
|
if (!StaticallyGreater.hasValue()) {
|
|
Prolog->addSuccessor(Epilog);
|
|
numAdded = TII->insertBranch(*Prolog, Epilog, LastPro, Cond, DebugLoc());
|
|
} else if (*StaticallyGreater == false) {
|
|
Prolog->addSuccessor(Epilog);
|
|
Prolog->removeSuccessor(LastPro);
|
|
LastEpi->removeSuccessor(Epilog);
|
|
numAdded = TII->insertBranch(*Prolog, Epilog, nullptr, Cond, DebugLoc());
|
|
removePhis(Epilog, LastEpi);
|
|
// Remove the blocks that are no longer referenced.
|
|
if (LastPro != LastEpi) {
|
|
LastEpi->clear();
|
|
LastEpi->eraseFromParent();
|
|
}
|
|
if (LastPro == KernelBB) {
|
|
LoopInfo->disposed();
|
|
NewKernel = nullptr;
|
|
}
|
|
LastPro->clear();
|
|
LastPro->eraseFromParent();
|
|
} else {
|
|
numAdded = TII->insertBranch(*Prolog, LastPro, nullptr, Cond, DebugLoc());
|
|
removePhis(Epilog, Prolog);
|
|
}
|
|
LastPro = Prolog;
|
|
LastEpi = Epilog;
|
|
for (MachineBasicBlock::reverse_instr_iterator I = Prolog->instr_rbegin(),
|
|
E = Prolog->instr_rend();
|
|
I != E && numAdded > 0; ++I, --numAdded)
|
|
updateInstruction(&*I, false, j, 0, VRMap);
|
|
}
|
|
|
|
if (NewKernel) {
|
|
LoopInfo->setPreheader(PrologBBs[MaxIter]);
|
|
LoopInfo->adjustTripCount(-(MaxIter + 1));
|
|
}
|
|
}
|
|
|
|
/// Return true if we can compute the amount the instruction changes
|
|
/// during each iteration. Set Delta to the amount of the change.
|
|
bool ModuloScheduleExpander::computeDelta(MachineInstr &MI, unsigned &Delta) {
|
|
const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
|
|
const MachineOperand *BaseOp;
|
|
int64_t Offset;
|
|
bool OffsetIsScalable;
|
|
if (!TII->getMemOperandWithOffset(MI, BaseOp, Offset, OffsetIsScalable, TRI))
|
|
return false;
|
|
|
|
// FIXME: This algorithm assumes instructions have fixed-size offsets.
|
|
if (OffsetIsScalable)
|
|
return false;
|
|
|
|
if (!BaseOp->isReg())
|
|
return false;
|
|
|
|
Register BaseReg = BaseOp->getReg();
|
|
|
|
MachineRegisterInfo &MRI = MF.getRegInfo();
|
|
// Check if there is a Phi. If so, get the definition in the loop.
|
|
MachineInstr *BaseDef = MRI.getVRegDef(BaseReg);
|
|
if (BaseDef && BaseDef->isPHI()) {
|
|
BaseReg = getLoopPhiReg(*BaseDef, MI.getParent());
|
|
BaseDef = MRI.getVRegDef(BaseReg);
|
|
}
|
|
if (!BaseDef)
|
|
return false;
|
|
|
|
int D = 0;
|
|
if (!TII->getIncrementValue(*BaseDef, D) && D >= 0)
|
|
return false;
|
|
|
|
Delta = D;
|
|
return true;
|
|
}
|
|
|
|
/// Update the memory operand with a new offset when the pipeliner
|
|
/// generates a new copy of the instruction that refers to a
|
|
/// different memory location.
|
|
void ModuloScheduleExpander::updateMemOperands(MachineInstr &NewMI,
|
|
MachineInstr &OldMI,
|
|
unsigned Num) {
|
|
if (Num == 0)
|
|
return;
|
|
// If the instruction has memory operands, then adjust the offset
|
|
// when the instruction appears in different stages.
|
|
if (NewMI.memoperands_empty())
|
|
return;
|
|
SmallVector<MachineMemOperand *, 2> NewMMOs;
|
|
for (MachineMemOperand *MMO : NewMI.memoperands()) {
|
|
// TODO: Figure out whether isAtomic is really necessary (see D57601).
|
|
if (MMO->isVolatile() || MMO->isAtomic() ||
|
|
(MMO->isInvariant() && MMO->isDereferenceable()) ||
|
|
(!MMO->getValue())) {
|
|
NewMMOs.push_back(MMO);
|
|
continue;
|
|
}
|
|
unsigned Delta;
|
|
if (Num != UINT_MAX && computeDelta(OldMI, Delta)) {
|
|
int64_t AdjOffset = Delta * Num;
|
|
NewMMOs.push_back(
|
|
MF.getMachineMemOperand(MMO, AdjOffset, MMO->getSize()));
|
|
} else {
|
|
NewMMOs.push_back(
|
|
MF.getMachineMemOperand(MMO, 0, MemoryLocation::UnknownSize));
|
|
}
|
|
}
|
|
NewMI.setMemRefs(MF, NewMMOs);
|
|
}
|
|
|
|
/// Clone the instruction for the new pipelined loop and update the
|
|
/// memory operands, if needed.
|
|
MachineInstr *ModuloScheduleExpander::cloneInstr(MachineInstr *OldMI,
|
|
unsigned CurStageNum,
|
|
unsigned InstStageNum) {
|
|
MachineInstr *NewMI = MF.CloneMachineInstr(OldMI);
|
|
// Check for tied operands in inline asm instructions. This should be handled
|
|
// elsewhere, but I'm not sure of the best solution.
|
|
if (OldMI->isInlineAsm())
|
|
for (unsigned i = 0, e = OldMI->getNumOperands(); i != e; ++i) {
|
|
const auto &MO = OldMI->getOperand(i);
|
|
if (MO.isReg() && MO.isUse())
|
|
break;
|
|
unsigned UseIdx;
|
|
if (OldMI->isRegTiedToUseOperand(i, &UseIdx))
|
|
NewMI->tieOperands(i, UseIdx);
|
|
}
|
|
updateMemOperands(*NewMI, *OldMI, CurStageNum - InstStageNum);
|
|
return NewMI;
|
|
}
|
|
|
|
/// Clone the instruction for the new pipelined loop. If needed, this
|
|
/// function updates the instruction using the values saved in the
|
|
/// InstrChanges structure.
|
|
MachineInstr *ModuloScheduleExpander::cloneAndChangeInstr(
|
|
MachineInstr *OldMI, unsigned CurStageNum, unsigned InstStageNum) {
|
|
MachineInstr *NewMI = MF.CloneMachineInstr(OldMI);
|
|
auto It = InstrChanges.find(OldMI);
|
|
if (It != InstrChanges.end()) {
|
|
std::pair<unsigned, int64_t> RegAndOffset = It->second;
|
|
unsigned BasePos, OffsetPos;
|
|
if (!TII->getBaseAndOffsetPosition(*OldMI, BasePos, OffsetPos))
|
|
return nullptr;
|
|
int64_t NewOffset = OldMI->getOperand(OffsetPos).getImm();
|
|
MachineInstr *LoopDef = findDefInLoop(RegAndOffset.first);
|
|
if (Schedule.getStage(LoopDef) > (signed)InstStageNum)
|
|
NewOffset += RegAndOffset.second * (CurStageNum - InstStageNum);
|
|
NewMI->getOperand(OffsetPos).setImm(NewOffset);
|
|
}
|
|
updateMemOperands(*NewMI, *OldMI, CurStageNum - InstStageNum);
|
|
return NewMI;
|
|
}
|
|
|
|
/// Update the machine instruction with new virtual registers. This
|
|
/// function may change the defintions and/or uses.
|
|
void ModuloScheduleExpander::updateInstruction(MachineInstr *NewMI,
|
|
bool LastDef,
|
|
unsigned CurStageNum,
|
|
unsigned InstrStageNum,
|
|
ValueMapTy *VRMap) {
|
|
for (unsigned i = 0, e = NewMI->getNumOperands(); i != e; ++i) {
|
|
MachineOperand &MO = NewMI->getOperand(i);
|
|
if (!MO.isReg() || !Register::isVirtualRegister(MO.getReg()))
|
|
continue;
|
|
Register reg = MO.getReg();
|
|
if (MO.isDef()) {
|
|
// Create a new virtual register for the definition.
|
|
const TargetRegisterClass *RC = MRI.getRegClass(reg);
|
|
Register NewReg = MRI.createVirtualRegister(RC);
|
|
MO.setReg(NewReg);
|
|
VRMap[CurStageNum][reg] = NewReg;
|
|
if (LastDef)
|
|
replaceRegUsesAfterLoop(reg, NewReg, BB, MRI, LIS);
|
|
} else if (MO.isUse()) {
|
|
MachineInstr *Def = MRI.getVRegDef(reg);
|
|
// Compute the stage that contains the last definition for instruction.
|
|
int DefStageNum = Schedule.getStage(Def);
|
|
unsigned StageNum = CurStageNum;
|
|
if (DefStageNum != -1 && (int)InstrStageNum > DefStageNum) {
|
|
// Compute the difference in stages between the defintion and the use.
|
|
unsigned StageDiff = (InstrStageNum - DefStageNum);
|
|
// Make an adjustment to get the last definition.
|
|
StageNum -= StageDiff;
|
|
}
|
|
if (VRMap[StageNum].count(reg))
|
|
MO.setReg(VRMap[StageNum][reg]);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Return the instruction in the loop that defines the register.
|
|
/// If the definition is a Phi, then follow the Phi operand to
|
|
/// the instruction in the loop.
|
|
MachineInstr *ModuloScheduleExpander::findDefInLoop(unsigned Reg) {
|
|
SmallPtrSet<MachineInstr *, 8> Visited;
|
|
MachineInstr *Def = MRI.getVRegDef(Reg);
|
|
while (Def->isPHI()) {
|
|
if (!Visited.insert(Def).second)
|
|
break;
|
|
for (unsigned i = 1, e = Def->getNumOperands(); i < e; i += 2)
|
|
if (Def->getOperand(i + 1).getMBB() == BB) {
|
|
Def = MRI.getVRegDef(Def->getOperand(i).getReg());
|
|
break;
|
|
}
|
|
}
|
|
return Def;
|
|
}
|
|
|
|
/// Return the new name for the value from the previous stage.
|
|
unsigned ModuloScheduleExpander::getPrevMapVal(
|
|
unsigned StageNum, unsigned PhiStage, unsigned LoopVal, unsigned LoopStage,
|
|
ValueMapTy *VRMap, MachineBasicBlock *BB) {
|
|
unsigned PrevVal = 0;
|
|
if (StageNum > PhiStage) {
|
|
MachineInstr *LoopInst = MRI.getVRegDef(LoopVal);
|
|
if (PhiStage == LoopStage && VRMap[StageNum - 1].count(LoopVal))
|
|
// The name is defined in the previous stage.
|
|
PrevVal = VRMap[StageNum - 1][LoopVal];
|
|
else if (VRMap[StageNum].count(LoopVal))
|
|
// The previous name is defined in the current stage when the instruction
|
|
// order is swapped.
|
|
PrevVal = VRMap[StageNum][LoopVal];
|
|
else if (!LoopInst->isPHI() || LoopInst->getParent() != BB)
|
|
// The loop value hasn't yet been scheduled.
|
|
PrevVal = LoopVal;
|
|
else if (StageNum == PhiStage + 1)
|
|
// The loop value is another phi, which has not been scheduled.
|
|
PrevVal = getInitPhiReg(*LoopInst, BB);
|
|
else if (StageNum > PhiStage + 1 && LoopInst->getParent() == BB)
|
|
// The loop value is another phi, which has been scheduled.
|
|
PrevVal =
|
|
getPrevMapVal(StageNum - 1, PhiStage, getLoopPhiReg(*LoopInst, BB),
|
|
LoopStage, VRMap, BB);
|
|
}
|
|
return PrevVal;
|
|
}
|
|
|
|
/// Rewrite the Phi values in the specified block to use the mappings
|
|
/// from the initial operand. Once the Phi is scheduled, we switch
|
|
/// to using the loop value instead of the Phi value, so those names
|
|
/// do not need to be rewritten.
|
|
void ModuloScheduleExpander::rewritePhiValues(MachineBasicBlock *NewBB,
|
|
unsigned StageNum,
|
|
ValueMapTy *VRMap,
|
|
InstrMapTy &InstrMap) {
|
|
for (auto &PHI : BB->phis()) {
|
|
unsigned InitVal = 0;
|
|
unsigned LoopVal = 0;
|
|
getPhiRegs(PHI, BB, InitVal, LoopVal);
|
|
Register PhiDef = PHI.getOperand(0).getReg();
|
|
|
|
unsigned PhiStage = (unsigned)Schedule.getStage(MRI.getVRegDef(PhiDef));
|
|
unsigned LoopStage = (unsigned)Schedule.getStage(MRI.getVRegDef(LoopVal));
|
|
unsigned NumPhis = getStagesForPhi(PhiDef);
|
|
if (NumPhis > StageNum)
|
|
NumPhis = StageNum;
|
|
for (unsigned np = 0; np <= NumPhis; ++np) {
|
|
unsigned NewVal =
|
|
getPrevMapVal(StageNum - np, PhiStage, LoopVal, LoopStage, VRMap, BB);
|
|
if (!NewVal)
|
|
NewVal = InitVal;
|
|
rewriteScheduledInstr(NewBB, InstrMap, StageNum - np, np, &PHI, PhiDef,
|
|
NewVal);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Rewrite a previously scheduled instruction to use the register value
|
|
/// from the new instruction. Make sure the instruction occurs in the
|
|
/// basic block, and we don't change the uses in the new instruction.
|
|
void ModuloScheduleExpander::rewriteScheduledInstr(
|
|
MachineBasicBlock *BB, InstrMapTy &InstrMap, unsigned CurStageNum,
|
|
unsigned PhiNum, MachineInstr *Phi, unsigned OldReg, unsigned NewReg,
|
|
unsigned PrevReg) {
|
|
bool InProlog = (CurStageNum < (unsigned)Schedule.getNumStages() - 1);
|
|
int StagePhi = Schedule.getStage(Phi) + PhiNum;
|
|
// Rewrite uses that have been scheduled already to use the new
|
|
// Phi register.
|
|
for (MachineRegisterInfo::use_iterator UI = MRI.use_begin(OldReg),
|
|
EI = MRI.use_end();
|
|
UI != EI;) {
|
|
MachineOperand &UseOp = *UI;
|
|
MachineInstr *UseMI = UseOp.getParent();
|
|
++UI;
|
|
if (UseMI->getParent() != BB)
|
|
continue;
|
|
if (UseMI->isPHI()) {
|
|
if (!Phi->isPHI() && UseMI->getOperand(0).getReg() == NewReg)
|
|
continue;
|
|
if (getLoopPhiReg(*UseMI, BB) != OldReg)
|
|
continue;
|
|
}
|
|
InstrMapTy::iterator OrigInstr = InstrMap.find(UseMI);
|
|
assert(OrigInstr != InstrMap.end() && "Instruction not scheduled.");
|
|
MachineInstr *OrigMI = OrigInstr->second;
|
|
int StageSched = Schedule.getStage(OrigMI);
|
|
int CycleSched = Schedule.getCycle(OrigMI);
|
|
unsigned ReplaceReg = 0;
|
|
// This is the stage for the scheduled instruction.
|
|
if (StagePhi == StageSched && Phi->isPHI()) {
|
|
int CyclePhi = Schedule.getCycle(Phi);
|
|
if (PrevReg && InProlog)
|
|
ReplaceReg = PrevReg;
|
|
else if (PrevReg && !isLoopCarried(*Phi) &&
|
|
(CyclePhi <= CycleSched || OrigMI->isPHI()))
|
|
ReplaceReg = PrevReg;
|
|
else
|
|
ReplaceReg = NewReg;
|
|
}
|
|
// The scheduled instruction occurs before the scheduled Phi, and the
|
|
// Phi is not loop carried.
|
|
if (!InProlog && StagePhi + 1 == StageSched && !isLoopCarried(*Phi))
|
|
ReplaceReg = NewReg;
|
|
if (StagePhi > StageSched && Phi->isPHI())
|
|
ReplaceReg = NewReg;
|
|
if (!InProlog && !Phi->isPHI() && StagePhi < StageSched)
|
|
ReplaceReg = NewReg;
|
|
if (ReplaceReg) {
|
|
MRI.constrainRegClass(ReplaceReg, MRI.getRegClass(OldReg));
|
|
UseOp.setReg(ReplaceReg);
|
|
}
|
|
}
|
|
}
|
|
|
|
bool ModuloScheduleExpander::isLoopCarried(MachineInstr &Phi) {
|
|
if (!Phi.isPHI())
|
|
return false;
|
|
int DefCycle = Schedule.getCycle(&Phi);
|
|
int DefStage = Schedule.getStage(&Phi);
|
|
|
|
unsigned InitVal = 0;
|
|
unsigned LoopVal = 0;
|
|
getPhiRegs(Phi, Phi.getParent(), InitVal, LoopVal);
|
|
MachineInstr *Use = MRI.getVRegDef(LoopVal);
|
|
if (!Use || Use->isPHI())
|
|
return true;
|
|
int LoopCycle = Schedule.getCycle(Use);
|
|
int LoopStage = Schedule.getStage(Use);
|
|
return (LoopCycle > DefCycle) || (LoopStage <= DefStage);
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// PeelingModuloScheduleExpander implementation
|
|
//===----------------------------------------------------------------------===//
|
|
// This is a reimplementation of ModuloScheduleExpander that works by creating
|
|
// a fully correct steady-state kernel and peeling off the prolog and epilogs.
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
namespace {
|
|
// Remove any dead phis in MBB. Dead phis either have only one block as input
|
|
// (in which case they are the identity) or have no uses.
|
|
void EliminateDeadPhis(MachineBasicBlock *MBB, MachineRegisterInfo &MRI,
|
|
LiveIntervals *LIS, bool KeepSingleSrcPhi = false) {
|
|
bool Changed = true;
|
|
while (Changed) {
|
|
Changed = false;
|
|
for (auto I = MBB->begin(); I != MBB->getFirstNonPHI();) {
|
|
MachineInstr &MI = *I++;
|
|
assert(MI.isPHI());
|
|
if (MRI.use_empty(MI.getOperand(0).getReg())) {
|
|
if (LIS)
|
|
LIS->RemoveMachineInstrFromMaps(MI);
|
|
MI.eraseFromParent();
|
|
Changed = true;
|
|
} else if (!KeepSingleSrcPhi && MI.getNumExplicitOperands() == 3) {
|
|
MRI.constrainRegClass(MI.getOperand(1).getReg(),
|
|
MRI.getRegClass(MI.getOperand(0).getReg()));
|
|
MRI.replaceRegWith(MI.getOperand(0).getReg(),
|
|
MI.getOperand(1).getReg());
|
|
if (LIS)
|
|
LIS->RemoveMachineInstrFromMaps(MI);
|
|
MI.eraseFromParent();
|
|
Changed = true;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Rewrites the kernel block in-place to adhere to the given schedule.
|
|
/// KernelRewriter holds all of the state required to perform the rewriting.
|
|
class KernelRewriter {
|
|
ModuloSchedule &S;
|
|
MachineBasicBlock *BB;
|
|
MachineBasicBlock *PreheaderBB, *ExitBB;
|
|
MachineRegisterInfo &MRI;
|
|
const TargetInstrInfo *TII;
|
|
LiveIntervals *LIS;
|
|
|
|
// Map from register class to canonical undef register for that class.
|
|
DenseMap<const TargetRegisterClass *, Register> Undefs;
|
|
// Map from <LoopReg, InitReg> to phi register for all created phis. Note that
|
|
// this map is only used when InitReg is non-undef.
|
|
DenseMap<std::pair<unsigned, unsigned>, Register> Phis;
|
|
// Map from LoopReg to phi register where the InitReg is undef.
|
|
DenseMap<Register, Register> UndefPhis;
|
|
|
|
// Reg is used by MI. Return the new register MI should use to adhere to the
|
|
// schedule. Insert phis as necessary.
|
|
Register remapUse(Register Reg, MachineInstr &MI);
|
|
// Insert a phi that carries LoopReg from the loop body and InitReg otherwise.
|
|
// If InitReg is not given it is chosen arbitrarily. It will either be undef
|
|
// or will be chosen so as to share another phi.
|
|
Register phi(Register LoopReg, Optional<Register> InitReg = {},
|
|
const TargetRegisterClass *RC = nullptr);
|
|
// Create an undef register of the given register class.
|
|
Register undef(const TargetRegisterClass *RC);
|
|
|
|
public:
|
|
KernelRewriter(MachineLoop &L, ModuloSchedule &S,
|
|
LiveIntervals *LIS = nullptr);
|
|
void rewrite();
|
|
};
|
|
} // namespace
|
|
|
|
KernelRewriter::KernelRewriter(MachineLoop &L, ModuloSchedule &S,
|
|
LiveIntervals *LIS)
|
|
: S(S), BB(L.getTopBlock()), PreheaderBB(L.getLoopPreheader()),
|
|
ExitBB(L.getExitBlock()), MRI(BB->getParent()->getRegInfo()),
|
|
TII(BB->getParent()->getSubtarget().getInstrInfo()), LIS(LIS) {
|
|
PreheaderBB = *BB->pred_begin();
|
|
if (PreheaderBB == BB)
|
|
PreheaderBB = *std::next(BB->pred_begin());
|
|
}
|
|
|
|
void KernelRewriter::rewrite() {
|
|
// Rearrange the loop to be in schedule order. Note that the schedule may
|
|
// contain instructions that are not owned by the loop block (InstrChanges and
|
|
// friends), so we gracefully handle unowned instructions and delete any
|
|
// instructions that weren't in the schedule.
|
|
auto InsertPt = BB->getFirstTerminator();
|
|
MachineInstr *FirstMI = nullptr;
|
|
for (MachineInstr *MI : S.getInstructions()) {
|
|
if (MI->isPHI())
|
|
continue;
|
|
if (MI->getParent())
|
|
MI->removeFromParent();
|
|
BB->insert(InsertPt, MI);
|
|
if (!FirstMI)
|
|
FirstMI = MI;
|
|
}
|
|
assert(FirstMI && "Failed to find first MI in schedule");
|
|
|
|
// At this point all of the scheduled instructions are between FirstMI
|
|
// and the end of the block. Kill from the first non-phi to FirstMI.
|
|
for (auto I = BB->getFirstNonPHI(); I != FirstMI->getIterator();) {
|
|
if (LIS)
|
|
LIS->RemoveMachineInstrFromMaps(*I);
|
|
(I++)->eraseFromParent();
|
|
}
|
|
|
|
// Now remap every instruction in the loop.
|
|
for (MachineInstr &MI : *BB) {
|
|
if (MI.isPHI() || MI.isTerminator())
|
|
continue;
|
|
for (MachineOperand &MO : MI.uses()) {
|
|
if (!MO.isReg() || MO.getReg().isPhysical() || MO.isImplicit())
|
|
continue;
|
|
Register Reg = remapUse(MO.getReg(), MI);
|
|
MO.setReg(Reg);
|
|
}
|
|
}
|
|
EliminateDeadPhis(BB, MRI, LIS);
|
|
|
|
// Ensure a phi exists for all instructions that are either referenced by
|
|
// an illegal phi or by an instruction outside the loop. This allows us to
|
|
// treat remaps of these values the same as "normal" values that come from
|
|
// loop-carried phis.
|
|
for (auto MI = BB->getFirstNonPHI(); MI != BB->end(); ++MI) {
|
|
if (MI->isPHI()) {
|
|
Register R = MI->getOperand(0).getReg();
|
|
phi(R);
|
|
continue;
|
|
}
|
|
|
|
for (MachineOperand &Def : MI->defs()) {
|
|
for (MachineInstr &MI : MRI.use_instructions(Def.getReg())) {
|
|
if (MI.getParent() != BB) {
|
|
phi(Def.getReg());
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
Register KernelRewriter::remapUse(Register Reg, MachineInstr &MI) {
|
|
MachineInstr *Producer = MRI.getUniqueVRegDef(Reg);
|
|
if (!Producer)
|
|
return Reg;
|
|
|
|
int ConsumerStage = S.getStage(&MI);
|
|
if (!Producer->isPHI()) {
|
|
// Non-phi producers are simple to remap. Insert as many phis as the
|
|
// difference between the consumer and producer stages.
|
|
if (Producer->getParent() != BB)
|
|
// Producer was not inside the loop. Use the register as-is.
|
|
return Reg;
|
|
int ProducerStage = S.getStage(Producer);
|
|
assert(ConsumerStage != -1 &&
|
|
"In-loop consumer should always be scheduled!");
|
|
assert(ConsumerStage >= ProducerStage);
|
|
unsigned StageDiff = ConsumerStage - ProducerStage;
|
|
|
|
for (unsigned I = 0; I < StageDiff; ++I)
|
|
Reg = phi(Reg);
|
|
return Reg;
|
|
}
|
|
|
|
// First, dive through the phi chain to find the defaults for the generated
|
|
// phis.
|
|
SmallVector<Optional<Register>, 4> Defaults;
|
|
Register LoopReg = Reg;
|
|
auto LoopProducer = Producer;
|
|
while (LoopProducer->isPHI() && LoopProducer->getParent() == BB) {
|
|
LoopReg = getLoopPhiReg(*LoopProducer, BB);
|
|
Defaults.emplace_back(getInitPhiReg(*LoopProducer, BB));
|
|
LoopProducer = MRI.getUniqueVRegDef(LoopReg);
|
|
assert(LoopProducer);
|
|
}
|
|
int LoopProducerStage = S.getStage(LoopProducer);
|
|
|
|
Optional<Register> IllegalPhiDefault;
|
|
|
|
if (LoopProducerStage == -1) {
|
|
// Do nothing.
|
|
} else if (LoopProducerStage > ConsumerStage) {
|
|
// This schedule is only representable if ProducerStage == ConsumerStage+1.
|
|
// In addition, Consumer's cycle must be scheduled after Producer in the
|
|
// rescheduled loop. This is enforced by the pipeliner's ASAP and ALAP
|
|
// functions.
|
|
#ifndef NDEBUG // Silence unused variables in non-asserts mode.
|
|
int LoopProducerCycle = S.getCycle(LoopProducer);
|
|
int ConsumerCycle = S.getCycle(&MI);
|
|
#endif
|
|
assert(LoopProducerCycle <= ConsumerCycle);
|
|
assert(LoopProducerStage == ConsumerStage + 1);
|
|
// Peel off the first phi from Defaults and insert a phi between producer
|
|
// and consumer. This phi will not be at the front of the block so we
|
|
// consider it illegal. It will only exist during the rewrite process; it
|
|
// needs to exist while we peel off prologs because these could take the
|
|
// default value. After that we can replace all uses with the loop producer
|
|
// value.
|
|
IllegalPhiDefault = Defaults.front();
|
|
Defaults.erase(Defaults.begin());
|
|
} else {
|
|
assert(ConsumerStage >= LoopProducerStage);
|
|
int StageDiff = ConsumerStage - LoopProducerStage;
|
|
if (StageDiff > 0) {
|
|
LLVM_DEBUG(dbgs() << " -- padding defaults array from " << Defaults.size()
|
|
<< " to " << (Defaults.size() + StageDiff) << "\n");
|
|
// If we need more phis than we have defaults for, pad out with undefs for
|
|
// the earliest phis, which are at the end of the defaults chain (the
|
|
// chain is in reverse order).
|
|
Defaults.resize(Defaults.size() + StageDiff, Defaults.empty()
|
|
? Optional<Register>()
|
|
: Defaults.back());
|
|
}
|
|
}
|
|
|
|
// Now we know the number of stages to jump back, insert the phi chain.
|
|
auto DefaultI = Defaults.rbegin();
|
|
while (DefaultI != Defaults.rend())
|
|
LoopReg = phi(LoopReg, *DefaultI++, MRI.getRegClass(Reg));
|
|
|
|
if (IllegalPhiDefault.hasValue()) {
|
|
// The consumer optionally consumes LoopProducer in the same iteration
|
|
// (because the producer is scheduled at an earlier cycle than the consumer)
|
|
// or the initial value. To facilitate this we create an illegal block here
|
|
// by embedding a phi in the middle of the block. We will fix this up
|
|
// immediately prior to pruning.
|
|
auto RC = MRI.getRegClass(Reg);
|
|
Register R = MRI.createVirtualRegister(RC);
|
|
MachineInstr *IllegalPhi =
|
|
BuildMI(*BB, MI, DebugLoc(), TII->get(TargetOpcode::PHI), R)
|
|
.addReg(IllegalPhiDefault.getValue())
|
|
.addMBB(PreheaderBB) // Block choice is arbitrary and has no effect.
|
|
.addReg(LoopReg)
|
|
.addMBB(BB); // Block choice is arbitrary and has no effect.
|
|
// Illegal phi should belong to the producer stage so that it can be
|
|
// filtered correctly during peeling.
|
|
S.setStage(IllegalPhi, LoopProducerStage);
|
|
return R;
|
|
}
|
|
|
|
return LoopReg;
|
|
}
|
|
|
|
Register KernelRewriter::phi(Register LoopReg, Optional<Register> InitReg,
|
|
const TargetRegisterClass *RC) {
|
|
// If the init register is not undef, try and find an existing phi.
|
|
if (InitReg.hasValue()) {
|
|
auto I = Phis.find({LoopReg, InitReg.getValue()});
|
|
if (I != Phis.end())
|
|
return I->second;
|
|
} else {
|
|
for (auto &KV : Phis) {
|
|
if (KV.first.first == LoopReg)
|
|
return KV.second;
|
|
}
|
|
}
|
|
|
|
// InitReg is either undef or no existing phi takes InitReg as input. Try and
|
|
// find a phi that takes undef as input.
|
|
auto I = UndefPhis.find(LoopReg);
|
|
if (I != UndefPhis.end()) {
|
|
Register R = I->second;
|
|
if (!InitReg.hasValue())
|
|
// Found a phi taking undef as input, and this input is undef so return
|
|
// without any more changes.
|
|
return R;
|
|
// Found a phi taking undef as input, so rewrite it to take InitReg.
|
|
MachineInstr *MI = MRI.getVRegDef(R);
|
|
MI->getOperand(1).setReg(InitReg.getValue());
|
|
Phis.insert({{LoopReg, InitReg.getValue()}, R});
|
|
MRI.constrainRegClass(R, MRI.getRegClass(InitReg.getValue()));
|
|
UndefPhis.erase(I);
|
|
return R;
|
|
}
|
|
|
|
// Failed to find any existing phi to reuse, so create a new one.
|
|
if (!RC)
|
|
RC = MRI.getRegClass(LoopReg);
|
|
Register R = MRI.createVirtualRegister(RC);
|
|
if (InitReg.hasValue())
|
|
MRI.constrainRegClass(R, MRI.getRegClass(*InitReg));
|
|
BuildMI(*BB, BB->getFirstNonPHI(), DebugLoc(), TII->get(TargetOpcode::PHI), R)
|
|
.addReg(InitReg.hasValue() ? *InitReg : undef(RC))
|
|
.addMBB(PreheaderBB)
|
|
.addReg(LoopReg)
|
|
.addMBB(BB);
|
|
if (!InitReg.hasValue())
|
|
UndefPhis[LoopReg] = R;
|
|
else
|
|
Phis[{LoopReg, *InitReg}] = R;
|
|
return R;
|
|
}
|
|
|
|
Register KernelRewriter::undef(const TargetRegisterClass *RC) {
|
|
Register &R = Undefs[RC];
|
|
if (R == 0) {
|
|
// Create an IMPLICIT_DEF that defines this register if we need it.
|
|
// All uses of this should be removed by the time we have finished unrolling
|
|
// prologs and epilogs.
|
|
R = MRI.createVirtualRegister(RC);
|
|
auto *InsertBB = &PreheaderBB->getParent()->front();
|
|
BuildMI(*InsertBB, InsertBB->getFirstTerminator(), DebugLoc(),
|
|
TII->get(TargetOpcode::IMPLICIT_DEF), R);
|
|
}
|
|
return R;
|
|
}
|
|
|
|
namespace {
|
|
/// Describes an operand in the kernel of a pipelined loop. Characteristics of
|
|
/// the operand are discovered, such as how many in-loop PHIs it has to jump
|
|
/// through and defaults for these phis.
|
|
class KernelOperandInfo {
|
|
MachineBasicBlock *BB;
|
|
MachineRegisterInfo &MRI;
|
|
SmallVector<Register, 4> PhiDefaults;
|
|
MachineOperand *Source;
|
|
MachineOperand *Target;
|
|
|
|
public:
|
|
KernelOperandInfo(MachineOperand *MO, MachineRegisterInfo &MRI,
|
|
const SmallPtrSetImpl<MachineInstr *> &IllegalPhis)
|
|
: MRI(MRI) {
|
|
Source = MO;
|
|
BB = MO->getParent()->getParent();
|
|
while (isRegInLoop(MO)) {
|
|
MachineInstr *MI = MRI.getVRegDef(MO->getReg());
|
|
if (MI->isFullCopy()) {
|
|
MO = &MI->getOperand(1);
|
|
continue;
|
|
}
|
|
if (!MI->isPHI())
|
|
break;
|
|
// If this is an illegal phi, don't count it in distance.
|
|
if (IllegalPhis.count(MI)) {
|
|
MO = &MI->getOperand(3);
|
|
continue;
|
|
}
|
|
|
|
Register Default = getInitPhiReg(*MI, BB);
|
|
MO = MI->getOperand(2).getMBB() == BB ? &MI->getOperand(1)
|
|
: &MI->getOperand(3);
|
|
PhiDefaults.push_back(Default);
|
|
}
|
|
Target = MO;
|
|
}
|
|
|
|
bool operator==(const KernelOperandInfo &Other) const {
|
|
return PhiDefaults.size() == Other.PhiDefaults.size();
|
|
}
|
|
|
|
void print(raw_ostream &OS) const {
|
|
OS << "use of " << *Source << ": distance(" << PhiDefaults.size() << ") in "
|
|
<< *Source->getParent();
|
|
}
|
|
|
|
private:
|
|
bool isRegInLoop(MachineOperand *MO) {
|
|
return MO->isReg() && MO->getReg().isVirtual() &&
|
|
MRI.getVRegDef(MO->getReg())->getParent() == BB;
|
|
}
|
|
};
|
|
} // namespace
|
|
|
|
MachineBasicBlock *
|
|
PeelingModuloScheduleExpander::peelKernel(LoopPeelDirection LPD) {
|
|
MachineBasicBlock *NewBB = PeelSingleBlockLoop(LPD, BB, MRI, TII);
|
|
if (LPD == LPD_Front)
|
|
PeeledFront.push_back(NewBB);
|
|
else
|
|
PeeledBack.push_front(NewBB);
|
|
for (auto I = BB->begin(), NI = NewBB->begin(); !I->isTerminator();
|
|
++I, ++NI) {
|
|
CanonicalMIs[&*I] = &*I;
|
|
CanonicalMIs[&*NI] = &*I;
|
|
BlockMIs[{NewBB, &*I}] = &*NI;
|
|
BlockMIs[{BB, &*I}] = &*I;
|
|
}
|
|
return NewBB;
|
|
}
|
|
|
|
void PeelingModuloScheduleExpander::filterInstructions(MachineBasicBlock *MB,
|
|
int MinStage) {
|
|
for (auto I = MB->getFirstInstrTerminator()->getReverseIterator();
|
|
I != std::next(MB->getFirstNonPHI()->getReverseIterator());) {
|
|
MachineInstr *MI = &*I++;
|
|
int Stage = getStage(MI);
|
|
if (Stage == -1 || Stage >= MinStage)
|
|
continue;
|
|
|
|
for (MachineOperand &DefMO : MI->defs()) {
|
|
SmallVector<std::pair<MachineInstr *, Register>, 4> Subs;
|
|
for (MachineInstr &UseMI : MRI.use_instructions(DefMO.getReg())) {
|
|
// Only PHIs can use values from this block by construction.
|
|
// Match with the equivalent PHI in B.
|
|
assert(UseMI.isPHI());
|
|
Register Reg = getEquivalentRegisterIn(UseMI.getOperand(0).getReg(),
|
|
MI->getParent());
|
|
Subs.emplace_back(&UseMI, Reg);
|
|
}
|
|
for (auto &Sub : Subs)
|
|
Sub.first->substituteRegister(DefMO.getReg(), Sub.second, /*SubIdx=*/0,
|
|
*MRI.getTargetRegisterInfo());
|
|
}
|
|
if (LIS)
|
|
LIS->RemoveMachineInstrFromMaps(*MI);
|
|
MI->eraseFromParent();
|
|
}
|
|
}
|
|
|
|
void PeelingModuloScheduleExpander::moveStageBetweenBlocks(
|
|
MachineBasicBlock *DestBB, MachineBasicBlock *SourceBB, unsigned Stage) {
|
|
auto InsertPt = DestBB->getFirstNonPHI();
|
|
DenseMap<Register, Register> Remaps;
|
|
for (auto I = SourceBB->getFirstNonPHI(); I != SourceBB->end();) {
|
|
MachineInstr *MI = &*I++;
|
|
if (MI->isPHI()) {
|
|
// This is an illegal PHI. If we move any instructions using an illegal
|
|
// PHI, we need to create a legal Phi.
|
|
if (getStage(MI) != Stage) {
|
|
// The legal Phi is not necessary if the illegal phi's stage
|
|
// is being moved.
|
|
Register PhiR = MI->getOperand(0).getReg();
|
|
auto RC = MRI.getRegClass(PhiR);
|
|
Register NR = MRI.createVirtualRegister(RC);
|
|
MachineInstr *NI = BuildMI(*DestBB, DestBB->getFirstNonPHI(),
|
|
DebugLoc(), TII->get(TargetOpcode::PHI), NR)
|
|
.addReg(PhiR)
|
|
.addMBB(SourceBB);
|
|
BlockMIs[{DestBB, CanonicalMIs[MI]}] = NI;
|
|
CanonicalMIs[NI] = CanonicalMIs[MI];
|
|
Remaps[PhiR] = NR;
|
|
}
|
|
}
|
|
if (getStage(MI) != Stage)
|
|
continue;
|
|
MI->removeFromParent();
|
|
DestBB->insert(InsertPt, MI);
|
|
auto *KernelMI = CanonicalMIs[MI];
|
|
BlockMIs[{DestBB, KernelMI}] = MI;
|
|
BlockMIs.erase({SourceBB, KernelMI});
|
|
}
|
|
SmallVector<MachineInstr *, 4> PhiToDelete;
|
|
for (MachineInstr &MI : DestBB->phis()) {
|
|
assert(MI.getNumOperands() == 3);
|
|
MachineInstr *Def = MRI.getVRegDef(MI.getOperand(1).getReg());
|
|
// If the instruction referenced by the phi is moved inside the block
|
|
// we don't need the phi anymore.
|
|
if (getStage(Def) == Stage) {
|
|
Register PhiReg = MI.getOperand(0).getReg();
|
|
assert(Def->findRegisterDefOperandIdx(MI.getOperand(1).getReg()) != -1);
|
|
MRI.replaceRegWith(MI.getOperand(0).getReg(), MI.getOperand(1).getReg());
|
|
MI.getOperand(0).setReg(PhiReg);
|
|
PhiToDelete.push_back(&MI);
|
|
}
|
|
}
|
|
for (auto *P : PhiToDelete)
|
|
P->eraseFromParent();
|
|
InsertPt = DestBB->getFirstNonPHI();
|
|
// Helper to clone Phi instructions into the destination block. We clone Phi
|
|
// greedily to avoid combinatorial explosion of Phi instructions.
|
|
auto clonePhi = [&](MachineInstr *Phi) {
|
|
MachineInstr *NewMI = MF.CloneMachineInstr(Phi);
|
|
DestBB->insert(InsertPt, NewMI);
|
|
Register OrigR = Phi->getOperand(0).getReg();
|
|
Register R = MRI.createVirtualRegister(MRI.getRegClass(OrigR));
|
|
NewMI->getOperand(0).setReg(R);
|
|
NewMI->getOperand(1).setReg(OrigR);
|
|
NewMI->getOperand(2).setMBB(*DestBB->pred_begin());
|
|
Remaps[OrigR] = R;
|
|
CanonicalMIs[NewMI] = CanonicalMIs[Phi];
|
|
BlockMIs[{DestBB, CanonicalMIs[Phi]}] = NewMI;
|
|
PhiNodeLoopIteration[NewMI] = PhiNodeLoopIteration[Phi];
|
|
return R;
|
|
};
|
|
for (auto I = DestBB->getFirstNonPHI(); I != DestBB->end(); ++I) {
|
|
for (MachineOperand &MO : I->uses()) {
|
|
if (!MO.isReg())
|
|
continue;
|
|
if (Remaps.count(MO.getReg()))
|
|
MO.setReg(Remaps[MO.getReg()]);
|
|
else {
|
|
// If we are using a phi from the source block we need to add a new phi
|
|
// pointing to the old one.
|
|
MachineInstr *Use = MRI.getUniqueVRegDef(MO.getReg());
|
|
if (Use && Use->isPHI() && Use->getParent() == SourceBB) {
|
|
Register R = clonePhi(Use);
|
|
MO.setReg(R);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
Register
|
|
PeelingModuloScheduleExpander::getPhiCanonicalReg(MachineInstr *CanonicalPhi,
|
|
MachineInstr *Phi) {
|
|
unsigned distance = PhiNodeLoopIteration[Phi];
|
|
MachineInstr *CanonicalUse = CanonicalPhi;
|
|
Register CanonicalUseReg = CanonicalUse->getOperand(0).getReg();
|
|
for (unsigned I = 0; I < distance; ++I) {
|
|
assert(CanonicalUse->isPHI());
|
|
assert(CanonicalUse->getNumOperands() == 5);
|
|
unsigned LoopRegIdx = 3, InitRegIdx = 1;
|
|
if (CanonicalUse->getOperand(2).getMBB() == CanonicalUse->getParent())
|
|
std::swap(LoopRegIdx, InitRegIdx);
|
|
CanonicalUseReg = CanonicalUse->getOperand(LoopRegIdx).getReg();
|
|
CanonicalUse = MRI.getVRegDef(CanonicalUseReg);
|
|
}
|
|
return CanonicalUseReg;
|
|
}
|
|
|
|
void PeelingModuloScheduleExpander::peelPrologAndEpilogs() {
|
|
BitVector LS(Schedule.getNumStages(), true);
|
|
BitVector AS(Schedule.getNumStages(), true);
|
|
LiveStages[BB] = LS;
|
|
AvailableStages[BB] = AS;
|
|
|
|
// Peel out the prologs.
|
|
LS.reset();
|
|
for (int I = 0; I < Schedule.getNumStages() - 1; ++I) {
|
|
LS[I] = 1;
|
|
Prologs.push_back(peelKernel(LPD_Front));
|
|
LiveStages[Prologs.back()] = LS;
|
|
AvailableStages[Prologs.back()] = LS;
|
|
}
|
|
|
|
// Create a block that will end up as the new loop exiting block (dominated by
|
|
// all prologs and epilogs). It will only contain PHIs, in the same order as
|
|
// BB's PHIs. This gives us a poor-man's LCSSA with the inductive property
|
|
// that the exiting block is a (sub) clone of BB. This in turn gives us the
|
|
// property that any value deffed in BB but used outside of BB is used by a
|
|
// PHI in the exiting block.
|
|
MachineBasicBlock *ExitingBB = CreateLCSSAExitingBlock();
|
|
EliminateDeadPhis(ExitingBB, MRI, LIS, /*KeepSingleSrcPhi=*/true);
|
|
// Push out the epilogs, again in reverse order.
|
|
// We can't assume anything about the minumum loop trip count at this point,
|
|
// so emit a fairly complex epilog.
|
|
|
|
// We first peel number of stages minus one epilogue. Then we remove dead
|
|
// stages and reorder instructions based on their stage. If we have 3 stages
|
|
// we generate first:
|
|
// E0[3, 2, 1]
|
|
// E1[3', 2']
|
|
// E2[3'']
|
|
// And then we move instructions based on their stages to have:
|
|
// E0[3]
|
|
// E1[2, 3']
|
|
// E2[1, 2', 3'']
|
|
// The transformation is legal because we only move instructions past
|
|
// instructions of a previous loop iteration.
|
|
for (int I = 1; I <= Schedule.getNumStages() - 1; ++I) {
|
|
Epilogs.push_back(peelKernel(LPD_Back));
|
|
MachineBasicBlock *B = Epilogs.back();
|
|
filterInstructions(B, Schedule.getNumStages() - I);
|
|
// Keep track at which iteration each phi belongs to. We need it to know
|
|
// what version of the variable to use during prologue/epilogue stitching.
|
|
EliminateDeadPhis(B, MRI, LIS, /*KeepSingleSrcPhi=*/true);
|
|
for (auto Phi = B->begin(), IE = B->getFirstNonPHI(); Phi != IE; ++Phi)
|
|
PhiNodeLoopIteration[&*Phi] = Schedule.getNumStages() - I;
|
|
}
|
|
for (size_t I = 0; I < Epilogs.size(); I++) {
|
|
LS.reset();
|
|
for (size_t J = I; J < Epilogs.size(); J++) {
|
|
int Iteration = J;
|
|
unsigned Stage = Schedule.getNumStages() - 1 + I - J;
|
|
// Move stage one block at a time so that Phi nodes are updated correctly.
|
|
for (size_t K = Iteration; K > I; K--)
|
|
moveStageBetweenBlocks(Epilogs[K - 1], Epilogs[K], Stage);
|
|
LS[Stage] = 1;
|
|
}
|
|
LiveStages[Epilogs[I]] = LS;
|
|
AvailableStages[Epilogs[I]] = AS;
|
|
}
|
|
|
|
// Now we've defined all the prolog and epilog blocks as a fallthrough
|
|
// sequence, add the edges that will be followed if the loop trip count is
|
|
// lower than the number of stages (connecting prologs directly with epilogs).
|
|
auto PI = Prologs.begin();
|
|
auto EI = Epilogs.begin();
|
|
assert(Prologs.size() == Epilogs.size());
|
|
for (; PI != Prologs.end(); ++PI, ++EI) {
|
|
MachineBasicBlock *Pred = *(*EI)->pred_begin();
|
|
(*PI)->addSuccessor(*EI);
|
|
for (MachineInstr &MI : (*EI)->phis()) {
|
|
Register Reg = MI.getOperand(1).getReg();
|
|
MachineInstr *Use = MRI.getUniqueVRegDef(Reg);
|
|
if (Use && Use->getParent() == Pred) {
|
|
MachineInstr *CanonicalUse = CanonicalMIs[Use];
|
|
if (CanonicalUse->isPHI()) {
|
|
// If the use comes from a phi we need to skip as many phi as the
|
|
// distance between the epilogue and the kernel. Trace through the phi
|
|
// chain to find the right value.
|
|
Reg = getPhiCanonicalReg(CanonicalUse, Use);
|
|
}
|
|
Reg = getEquivalentRegisterIn(Reg, *PI);
|
|
}
|
|
MI.addOperand(MachineOperand::CreateReg(Reg, /*isDef=*/false));
|
|
MI.addOperand(MachineOperand::CreateMBB(*PI));
|
|
}
|
|
}
|
|
|
|
// Create a list of all blocks in order.
|
|
SmallVector<MachineBasicBlock *, 8> Blocks;
|
|
llvm::copy(PeeledFront, std::back_inserter(Blocks));
|
|
Blocks.push_back(BB);
|
|
llvm::copy(PeeledBack, std::back_inserter(Blocks));
|
|
|
|
// Iterate in reverse order over all instructions, remapping as we go.
|
|
for (MachineBasicBlock *B : reverse(Blocks)) {
|
|
for (auto I = B->getFirstInstrTerminator()->getReverseIterator();
|
|
I != std::next(B->getFirstNonPHI()->getReverseIterator());) {
|
|
MachineInstr *MI = &*I++;
|
|
rewriteUsesOf(MI);
|
|
}
|
|
}
|
|
for (auto *MI : IllegalPhisToDelete) {
|
|
if (LIS)
|
|
LIS->RemoveMachineInstrFromMaps(*MI);
|
|
MI->eraseFromParent();
|
|
}
|
|
IllegalPhisToDelete.clear();
|
|
|
|
// Now all remapping has been done, we're free to optimize the generated code.
|
|
for (MachineBasicBlock *B : reverse(Blocks))
|
|
EliminateDeadPhis(B, MRI, LIS);
|
|
EliminateDeadPhis(ExitingBB, MRI, LIS);
|
|
}
|
|
|
|
MachineBasicBlock *PeelingModuloScheduleExpander::CreateLCSSAExitingBlock() {
|
|
MachineFunction &MF = *BB->getParent();
|
|
MachineBasicBlock *Exit = *BB->succ_begin();
|
|
if (Exit == BB)
|
|
Exit = *std::next(BB->succ_begin());
|
|
|
|
MachineBasicBlock *NewBB = MF.CreateMachineBasicBlock(BB->getBasicBlock());
|
|
MF.insert(std::next(BB->getIterator()), NewBB);
|
|
|
|
// Clone all phis in BB into NewBB and rewrite.
|
|
for (MachineInstr &MI : BB->phis()) {
|
|
auto RC = MRI.getRegClass(MI.getOperand(0).getReg());
|
|
Register OldR = MI.getOperand(3).getReg();
|
|
Register R = MRI.createVirtualRegister(RC);
|
|
SmallVector<MachineInstr *, 4> Uses;
|
|
for (MachineInstr &Use : MRI.use_instructions(OldR))
|
|
if (Use.getParent() != BB)
|
|
Uses.push_back(&Use);
|
|
for (MachineInstr *Use : Uses)
|
|
Use->substituteRegister(OldR, R, /*SubIdx=*/0,
|
|
*MRI.getTargetRegisterInfo());
|
|
MachineInstr *NI = BuildMI(NewBB, DebugLoc(), TII->get(TargetOpcode::PHI), R)
|
|
.addReg(OldR)
|
|
.addMBB(BB);
|
|
BlockMIs[{NewBB, &MI}] = NI;
|
|
CanonicalMIs[NI] = &MI;
|
|
}
|
|
BB->replaceSuccessor(Exit, NewBB);
|
|
Exit->replacePhiUsesWith(BB, NewBB);
|
|
NewBB->addSuccessor(Exit);
|
|
|
|
MachineBasicBlock *TBB = nullptr, *FBB = nullptr;
|
|
SmallVector<MachineOperand, 4> Cond;
|
|
bool CanAnalyzeBr = !TII->analyzeBranch(*BB, TBB, FBB, Cond);
|
|
(void)CanAnalyzeBr;
|
|
assert(CanAnalyzeBr && "Must be able to analyze the loop branch!");
|
|
TII->removeBranch(*BB);
|
|
TII->insertBranch(*BB, TBB == Exit ? NewBB : TBB, FBB == Exit ? NewBB : FBB,
|
|
Cond, DebugLoc());
|
|
TII->insertUnconditionalBranch(*NewBB, Exit, DebugLoc());
|
|
return NewBB;
|
|
}
|
|
|
|
Register
|
|
PeelingModuloScheduleExpander::getEquivalentRegisterIn(Register Reg,
|
|
MachineBasicBlock *BB) {
|
|
MachineInstr *MI = MRI.getUniqueVRegDef(Reg);
|
|
unsigned OpIdx = MI->findRegisterDefOperandIdx(Reg);
|
|
return BlockMIs[{BB, CanonicalMIs[MI]}]->getOperand(OpIdx).getReg();
|
|
}
|
|
|
|
void PeelingModuloScheduleExpander::rewriteUsesOf(MachineInstr *MI) {
|
|
if (MI->isPHI()) {
|
|
// This is an illegal PHI. The loop-carried (desired) value is operand 3,
|
|
// and it is produced by this block.
|
|
Register PhiR = MI->getOperand(0).getReg();
|
|
Register R = MI->getOperand(3).getReg();
|
|
int RMIStage = getStage(MRI.getUniqueVRegDef(R));
|
|
if (RMIStage != -1 && !AvailableStages[MI->getParent()].test(RMIStage))
|
|
R = MI->getOperand(1).getReg();
|
|
MRI.setRegClass(R, MRI.getRegClass(PhiR));
|
|
MRI.replaceRegWith(PhiR, R);
|
|
// Postpone deleting the Phi as it may be referenced by BlockMIs and used
|
|
// later to figure out how to remap registers.
|
|
MI->getOperand(0).setReg(PhiR);
|
|
IllegalPhisToDelete.push_back(MI);
|
|
return;
|
|
}
|
|
|
|
int Stage = getStage(MI);
|
|
if (Stage == -1 || LiveStages.count(MI->getParent()) == 0 ||
|
|
LiveStages[MI->getParent()].test(Stage))
|
|
// Instruction is live, no rewriting to do.
|
|
return;
|
|
|
|
for (MachineOperand &DefMO : MI->defs()) {
|
|
SmallVector<std::pair<MachineInstr *, Register>, 4> Subs;
|
|
for (MachineInstr &UseMI : MRI.use_instructions(DefMO.getReg())) {
|
|
// Only PHIs can use values from this block by construction.
|
|
// Match with the equivalent PHI in B.
|
|
assert(UseMI.isPHI());
|
|
Register Reg = getEquivalentRegisterIn(UseMI.getOperand(0).getReg(),
|
|
MI->getParent());
|
|
Subs.emplace_back(&UseMI, Reg);
|
|
}
|
|
for (auto &Sub : Subs)
|
|
Sub.first->substituteRegister(DefMO.getReg(), Sub.second, /*SubIdx=*/0,
|
|
*MRI.getTargetRegisterInfo());
|
|
}
|
|
if (LIS)
|
|
LIS->RemoveMachineInstrFromMaps(*MI);
|
|
MI->eraseFromParent();
|
|
}
|
|
|
|
void PeelingModuloScheduleExpander::fixupBranches() {
|
|
// Work outwards from the kernel.
|
|
bool KernelDisposed = false;
|
|
int TC = Schedule.getNumStages() - 1;
|
|
for (auto PI = Prologs.rbegin(), EI = Epilogs.rbegin(); PI != Prologs.rend();
|
|
++PI, ++EI, --TC) {
|
|
MachineBasicBlock *Prolog = *PI;
|
|
MachineBasicBlock *Fallthrough = *Prolog->succ_begin();
|
|
MachineBasicBlock *Epilog = *EI;
|
|
SmallVector<MachineOperand, 4> Cond;
|
|
TII->removeBranch(*Prolog);
|
|
Optional<bool> StaticallyGreater =
|
|
LoopInfo->createTripCountGreaterCondition(TC, *Prolog, Cond);
|
|
if (!StaticallyGreater.hasValue()) {
|
|
LLVM_DEBUG(dbgs() << "Dynamic: TC > " << TC << "\n");
|
|
// Dynamically branch based on Cond.
|
|
TII->insertBranch(*Prolog, Epilog, Fallthrough, Cond, DebugLoc());
|
|
} else if (*StaticallyGreater == false) {
|
|
LLVM_DEBUG(dbgs() << "Static-false: TC > " << TC << "\n");
|
|
// Prolog never falls through; branch to epilog and orphan interior
|
|
// blocks. Leave it to unreachable-block-elim to clean up.
|
|
Prolog->removeSuccessor(Fallthrough);
|
|
for (MachineInstr &P : Fallthrough->phis()) {
|
|
P.RemoveOperand(2);
|
|
P.RemoveOperand(1);
|
|
}
|
|
TII->insertUnconditionalBranch(*Prolog, Epilog, DebugLoc());
|
|
KernelDisposed = true;
|
|
} else {
|
|
LLVM_DEBUG(dbgs() << "Static-true: TC > " << TC << "\n");
|
|
// Prolog always falls through; remove incoming values in epilog.
|
|
Prolog->removeSuccessor(Epilog);
|
|
for (MachineInstr &P : Epilog->phis()) {
|
|
P.RemoveOperand(4);
|
|
P.RemoveOperand(3);
|
|
}
|
|
}
|
|
}
|
|
|
|
if (!KernelDisposed) {
|
|
LoopInfo->adjustTripCount(-(Schedule.getNumStages() - 1));
|
|
LoopInfo->setPreheader(Prologs.back());
|
|
} else {
|
|
LoopInfo->disposed();
|
|
}
|
|
}
|
|
|
|
void PeelingModuloScheduleExpander::rewriteKernel() {
|
|
KernelRewriter KR(*Schedule.getLoop(), Schedule);
|
|
KR.rewrite();
|
|
}
|
|
|
|
void PeelingModuloScheduleExpander::expand() {
|
|
BB = Schedule.getLoop()->getTopBlock();
|
|
Preheader = Schedule.getLoop()->getLoopPreheader();
|
|
LLVM_DEBUG(Schedule.dump());
|
|
LoopInfo = TII->analyzeLoopForPipelining(BB);
|
|
assert(LoopInfo);
|
|
|
|
rewriteKernel();
|
|
peelPrologAndEpilogs();
|
|
fixupBranches();
|
|
}
|
|
|
|
void PeelingModuloScheduleExpander::validateAgainstModuloScheduleExpander() {
|
|
BB = Schedule.getLoop()->getTopBlock();
|
|
Preheader = Schedule.getLoop()->getLoopPreheader();
|
|
|
|
// Dump the schedule before we invalidate and remap all its instructions.
|
|
// Stash it in a string so we can print it if we found an error.
|
|
std::string ScheduleDump;
|
|
raw_string_ostream OS(ScheduleDump);
|
|
Schedule.print(OS);
|
|
OS.flush();
|
|
|
|
// First, run the normal ModuleScheduleExpander. We don't support any
|
|
// InstrChanges.
|
|
assert(LIS && "Requires LiveIntervals!");
|
|
ModuloScheduleExpander MSE(MF, Schedule, *LIS,
|
|
ModuloScheduleExpander::InstrChangesTy());
|
|
MSE.expand();
|
|
MachineBasicBlock *ExpandedKernel = MSE.getRewrittenKernel();
|
|
if (!ExpandedKernel) {
|
|
// The expander optimized away the kernel. We can't do any useful checking.
|
|
MSE.cleanup();
|
|
return;
|
|
}
|
|
// Before running the KernelRewriter, re-add BB into the CFG.
|
|
Preheader->addSuccessor(BB);
|
|
|
|
// Now run the new expansion algorithm.
|
|
KernelRewriter KR(*Schedule.getLoop(), Schedule);
|
|
KR.rewrite();
|
|
peelPrologAndEpilogs();
|
|
|
|
// Collect all illegal phis that the new algorithm created. We'll give these
|
|
// to KernelOperandInfo.
|
|
SmallPtrSet<MachineInstr *, 4> IllegalPhis;
|
|
for (auto NI = BB->getFirstNonPHI(); NI != BB->end(); ++NI) {
|
|
if (NI->isPHI())
|
|
IllegalPhis.insert(&*NI);
|
|
}
|
|
|
|
// Co-iterate across both kernels. We expect them to be identical apart from
|
|
// phis and full COPYs (we look through both).
|
|
SmallVector<std::pair<KernelOperandInfo, KernelOperandInfo>, 8> KOIs;
|
|
auto OI = ExpandedKernel->begin();
|
|
auto NI = BB->begin();
|
|
for (; !OI->isTerminator() && !NI->isTerminator(); ++OI, ++NI) {
|
|
while (OI->isPHI() || OI->isFullCopy())
|
|
++OI;
|
|
while (NI->isPHI() || NI->isFullCopy())
|
|
++NI;
|
|
assert(OI->getOpcode() == NI->getOpcode() && "Opcodes don't match?!");
|
|
// Analyze every operand separately.
|
|
for (auto OOpI = OI->operands_begin(), NOpI = NI->operands_begin();
|
|
OOpI != OI->operands_end(); ++OOpI, ++NOpI)
|
|
KOIs.emplace_back(KernelOperandInfo(&*OOpI, MRI, IllegalPhis),
|
|
KernelOperandInfo(&*NOpI, MRI, IllegalPhis));
|
|
}
|
|
|
|
bool Failed = false;
|
|
for (auto &OldAndNew : KOIs) {
|
|
if (OldAndNew.first == OldAndNew.second)
|
|
continue;
|
|
Failed = true;
|
|
errs() << "Modulo kernel validation error: [\n";
|
|
errs() << " [golden] ";
|
|
OldAndNew.first.print(errs());
|
|
errs() << " ";
|
|
OldAndNew.second.print(errs());
|
|
errs() << "]\n";
|
|
}
|
|
|
|
if (Failed) {
|
|
errs() << "Golden reference kernel:\n";
|
|
ExpandedKernel->print(errs());
|
|
errs() << "New kernel:\n";
|
|
BB->print(errs());
|
|
errs() << ScheduleDump;
|
|
report_fatal_error(
|
|
"Modulo kernel validation (-pipeliner-experimental-cg) failed");
|
|
}
|
|
|
|
// Cleanup by removing BB from the CFG again as the original
|
|
// ModuloScheduleExpander intended.
|
|
Preheader->removeSuccessor(BB);
|
|
MSE.cleanup();
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// ModuloScheduleTestPass implementation
|
|
//===----------------------------------------------------------------------===//
|
|
// This pass constructs a ModuloSchedule from its module and runs
|
|
// ModuloScheduleExpander.
|
|
//
|
|
// The module is expected to contain a single-block analyzable loop.
|
|
// The total order of instructions is taken from the loop as-is.
|
|
// Instructions are expected to be annotated with a PostInstrSymbol.
|
|
// This PostInstrSymbol must have the following format:
|
|
// "Stage=%d Cycle=%d".
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
namespace {
|
|
class ModuloScheduleTest : public MachineFunctionPass {
|
|
public:
|
|
static char ID;
|
|
|
|
ModuloScheduleTest() : MachineFunctionPass(ID) {
|
|
initializeModuloScheduleTestPass(*PassRegistry::getPassRegistry());
|
|
}
|
|
|
|
bool runOnMachineFunction(MachineFunction &MF) override;
|
|
void runOnLoop(MachineFunction &MF, MachineLoop &L);
|
|
|
|
void getAnalysisUsage(AnalysisUsage &AU) const override {
|
|
AU.addRequired<MachineLoopInfo>();
|
|
AU.addRequired<LiveIntervals>();
|
|
MachineFunctionPass::getAnalysisUsage(AU);
|
|
}
|
|
};
|
|
} // namespace
|
|
|
|
char ModuloScheduleTest::ID = 0;
|
|
|
|
INITIALIZE_PASS_BEGIN(ModuloScheduleTest, "modulo-schedule-test",
|
|
"Modulo Schedule test pass", false, false)
|
|
INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
|
|
INITIALIZE_PASS_DEPENDENCY(LiveIntervals)
|
|
INITIALIZE_PASS_END(ModuloScheduleTest, "modulo-schedule-test",
|
|
"Modulo Schedule test pass", false, false)
|
|
|
|
bool ModuloScheduleTest::runOnMachineFunction(MachineFunction &MF) {
|
|
MachineLoopInfo &MLI = getAnalysis<MachineLoopInfo>();
|
|
for (auto *L : MLI) {
|
|
if (L->getTopBlock() != L->getBottomBlock())
|
|
continue;
|
|
runOnLoop(MF, *L);
|
|
return false;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
static void parseSymbolString(StringRef S, int &Cycle, int &Stage) {
|
|
std::pair<StringRef, StringRef> StageAndCycle = getToken(S, "_");
|
|
std::pair<StringRef, StringRef> StageTokenAndValue =
|
|
getToken(StageAndCycle.first, "-");
|
|
std::pair<StringRef, StringRef> CycleTokenAndValue =
|
|
getToken(StageAndCycle.second, "-");
|
|
if (StageTokenAndValue.first != "Stage" ||
|
|
CycleTokenAndValue.first != "_Cycle") {
|
|
llvm_unreachable(
|
|
"Bad post-instr symbol syntax: see comment in ModuloScheduleTest");
|
|
return;
|
|
}
|
|
|
|
StageTokenAndValue.second.drop_front().getAsInteger(10, Stage);
|
|
CycleTokenAndValue.second.drop_front().getAsInteger(10, Cycle);
|
|
|
|
dbgs() << " Stage=" << Stage << ", Cycle=" << Cycle << "\n";
|
|
}
|
|
|
|
void ModuloScheduleTest::runOnLoop(MachineFunction &MF, MachineLoop &L) {
|
|
LiveIntervals &LIS = getAnalysis<LiveIntervals>();
|
|
MachineBasicBlock *BB = L.getTopBlock();
|
|
dbgs() << "--- ModuloScheduleTest running on BB#" << BB->getNumber() << "\n";
|
|
|
|
DenseMap<MachineInstr *, int> Cycle, Stage;
|
|
std::vector<MachineInstr *> Instrs;
|
|
for (MachineInstr &MI : *BB) {
|
|
if (MI.isTerminator())
|
|
continue;
|
|
Instrs.push_back(&MI);
|
|
if (MCSymbol *Sym = MI.getPostInstrSymbol()) {
|
|
dbgs() << "Parsing post-instr symbol for " << MI;
|
|
parseSymbolString(Sym->getName(), Cycle[&MI], Stage[&MI]);
|
|
}
|
|
}
|
|
|
|
ModuloSchedule MS(MF, &L, std::move(Instrs), std::move(Cycle),
|
|
std::move(Stage));
|
|
ModuloScheduleExpander MSE(
|
|
MF, MS, LIS, /*InstrChanges=*/ModuloScheduleExpander::InstrChangesTy());
|
|
MSE.expand();
|
|
MSE.cleanup();
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// ModuloScheduleTestAnnotater implementation
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
void ModuloScheduleTestAnnotater::annotate() {
|
|
for (MachineInstr *MI : S.getInstructions()) {
|
|
SmallVector<char, 16> SV;
|
|
raw_svector_ostream OS(SV);
|
|
OS << "Stage-" << S.getStage(MI) << "_Cycle-" << S.getCycle(MI);
|
|
MCSymbol *Sym = MF.getContext().getOrCreateSymbol(OS.str());
|
|
MI->setPostInstrSymbol(MF, Sym);
|
|
}
|
|
}
|