lib/MCA/Stages/EntryStage.cpp

   1 //===---------------------- EntryStage.cpp ----------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 /// \file
   9 ///
  10 /// This file defines the Fetch stage of an instruction pipeline.  Its sole
  11 /// purpose in life is to produce instructions for the rest of the pipeline.
  12 ///
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "llvm/MCA/Stages/EntryStage.h"
  16 #include "llvm/MCA/Instruction.h"
  17
  18 namespace llvm {
  19 namespace mca {
  20
  21 bool EntryStage::hasWorkToComplete() const {
  22   return static_cast<bool>(CurrentInstruction);
  23 }
  24
  25 bool EntryStage::isAvailable(const InstRef & /* unused */) const {
  26   if (CurrentInstruction)
  27     return checkNextStage(CurrentInstruction);
  28   return false;
  29 }
  30
  31 void EntryStage::getNextInstruction() {
  32   assert(!CurrentInstruction && "There is already an instruction to process!");
  33   if (!SM.hasNext())
  34     return;
  35   SourceRef SR = SM.peekNext();
  36   std::unique_ptr<Instruction> Inst = std::make_unique<Instruction>(SR.second);
  37   CurrentInstruction = InstRef(SR.first, Inst.get());
  38   Instructions.emplace_back(std::move(Inst));
  39   SM.updateNext();
  40 }
  41
  42 llvm::Error EntryStage::execute(InstRef & /*unused */) {
  43   assert(CurrentInstruction && "There is no instruction to process!");
  44   if (llvm::Error Val = moveToTheNextStage(CurrentInstruction))
  45     return Val;
  46
  47   // Move the program counter.
  48   CurrentInstruction.invalidate();
  49   getNextInstruction();
  50   return llvm::ErrorSuccess();
  51 }
  52
  53 llvm::Error EntryStage::cycleStart() {
  54   if (!CurrentInstruction)
  55     getNextInstruction();
  56   return llvm::ErrorSuccess();
  57 }
  58
  59 llvm::Error EntryStage::cycleEnd() {
  60   // Find the first instruction which hasn't been retired.
  61   auto Range = make_range(&Instructions[NumRetired], Instructions.end());
  62   auto It = find_if(Range, [](const std::unique_ptr<Instruction> &I) {
  63     return !I->isRetired();
  64   });
  65
  66   NumRetired = std::distance(Instructions.begin(), It);
  67   // Erase instructions up to the first that hasn't been retired.
  68   if ((NumRetired * 2) >= Instructions.size()) {
  69     Instructions.erase(Instructions.begin(), It);
  70     NumRetired = 0;
  71   }
  72
  73   return llvm::ErrorSuccess();
  74 }
  75
  76 } // namespace mca
  77 } // namespace llvm