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
18namespace llvm {
19namespace mca {
20
21bool EntryStage::hasWorkToComplete() const {
22 return static_cast<bool>(CurrentInstruction) || !SM.isEnd();
23}
24
25bool EntryStage::isAvailable(const InstRef & /* unused */) const {
26 if (CurrentInstruction)
27 return checkNextStage(IR: CurrentInstruction);
28 return false;
29}
30
31Error 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
47llvm::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
57llvm::Error EntryStage::cycleStart() {
58 if (!CurrentInstruction)
59 return getNextInstruction();
60 return llvm::ErrorSuccess();
61}
62
63llvm::Error EntryStage::cycleResume() {
64 assert(!CurrentInstruction);
65 return getNextInstruction();
66}
67
68llvm::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