| 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) || !SM.isEnd(); |
| 23 | } |
| 24 | |
| 25 | bool EntryStage::isAvailable(const InstRef & /* unused */) const { |
| 26 | if (CurrentInstruction) |
| 27 | return checkNextStage(IR: CurrentInstruction); |
| 28 | return false; |
| 29 | } |
| 30 | |
| 31 | Error EntryStage::getNextInstruction() { |
| 32 | assert(!CurrentInstruction && "There is already an instruction to process!"); |
| 33 | if (!SM.hasNext()) { |
| 34 | if (!SM.isEnd()) |
| 35 | return llvm::make_error<InstStreamPause>(); |
| 36 | else |
| 37 | return llvm::ErrorSuccess(); |
| 38 | } |
| 39 | SourceRef SR = SM.peekNext(); |
| 40 | std::unique_ptr<Instruction> Inst = std::make_unique<Instruction>(args: SR.second); |
| 41 | CurrentInstruction = InstRef(SR.first, Inst.get()); |
| 42 | Instructions.emplace_back(Args: std::move(Inst)); |
| 43 | SM.updateNext(); |
| 44 | return llvm::ErrorSuccess(); |
| 45 | } |
| 46 | |
| 47 | llvm::Error EntryStage::execute(InstRef & /*unused */) { |
| 48 | assert(CurrentInstruction && "There is no instruction to process!"); |
| 49 | if (llvm::Error Val = moveToTheNextStage(IR&: CurrentInstruction)) |
| 50 | return Val; |
| 51 | |
| 52 | // Move the program counter. |
| 53 | CurrentInstruction.invalidate(); |
| 54 | return getNextInstruction(); |
| 55 | } |
| 56 | |
| 57 | llvm::Error EntryStage::cycleStart() { |
| 58 | if (!CurrentInstruction) |
| 59 | return getNextInstruction(); |
| 60 | return llvm::ErrorSuccess(); |
| 61 | } |
| 62 | |
| 63 | llvm::Error EntryStage::cycleResume() { |
| 64 | assert(!CurrentInstruction); |
| 65 | return getNextInstruction(); |
| 66 | } |
| 67 | |
| 68 | llvm::Error EntryStage::cycleEnd() { |
| 69 | // Find the first instruction which hasn't been retired. |
| 70 | auto Range = drop_begin(RangeOrContainer&: Instructions, N: NumRetired); |
| 71 | auto It = find_if(Range, P: [](const std::unique_ptr<Instruction> &I) { |
| 72 | return !I->isRetired(); |
| 73 | }); |
| 74 | |
| 75 | NumRetired = std::distance(first: Instructions.begin(), last: It); |
| 76 | // Erase instructions up to the first that hasn't been retired. |
| 77 | if ((NumRetired * 2) >= Instructions.size()) { |
| 78 | Instructions.erase(CS: Instructions.begin(), CE: It); |
| 79 | NumRetired = 0; |
| 80 | } |
| 81 | |
| 82 | return llvm::ErrorSuccess(); |
| 83 | } |
| 84 | |
| 85 | } // namespace mca |
| 86 | } // namespace llvm |
| 87 |