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//===---------------------- EntryStage.cpp ----------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
/// \file
///
/// This file defines the Fetch stage of an instruction pipeline. Its sole
/// purpose in life is to produce instructions for the rest of the pipeline.
///
//===----------------------------------------------------------------------===//
#include "llvm/MCA/Stages/EntryStage.h"
#include "llvm/MCA/Instruction.h"
namespace llvm {
namespace mca {
bool EntryStage::hasWorkToComplete() const {
return static_cast<bool>(CurrentInstruction) || !SM.isEnd();
}
bool EntryStage::isAvailable(const InstRef & /* unused */) const {
if (CurrentInstruction)
return checkNextStage(CurrentInstruction);
return false;
}
Error EntryStage::getNextInstruction() {
assert(!CurrentInstruction && "There is already an instruction to process!");
if (!SM.hasNext()) {
if (!SM.isEnd())
return llvm::make_error<InstStreamPause>();
else
return llvm::ErrorSuccess();
}
SourceRef SR = SM.peekNext();
std::unique_ptr<Instruction> Inst = std::make_unique<Instruction>(SR.second);
CurrentInstruction = InstRef(SR.first, Inst.get());
Instructions.emplace_back(std::move(Inst));
SM.updateNext();
return llvm::ErrorSuccess();
}
llvm::Error EntryStage::execute(InstRef & /*unused */) {
assert(CurrentInstruction && "There is no instruction to process!");
if (llvm::Error Val = moveToTheNextStage(CurrentInstruction))
return Val;
// Move the program counter.
CurrentInstruction.invalidate();
return getNextInstruction();
}
llvm::Error EntryStage::cycleStart() {
if (!CurrentInstruction)
return getNextInstruction();
return llvm::ErrorSuccess();
}
llvm::Error EntryStage::cycleResume() {
assert(!CurrentInstruction);
return getNextInstruction();
}
llvm::Error EntryStage::cycleEnd() {
// Find the first instruction which hasn't been retired.
auto Range =
make_range(Instructions.begin() + NumRetired, Instructions.end());
auto It = find_if(Range, [](const std::unique_ptr<Instruction> &I) {
return !I->isRetired();
});
NumRetired = std::distance(Instructions.begin(), It);
// Erase instructions up to the first that hasn't been retired.
if ((NumRetired * 2) >= Instructions.size()) {
Instructions.erase(Instructions.begin(), It);
NumRetired = 0;
}
return llvm::ErrorSuccess();
}
} // namespace mca
} // namespace llvm
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