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128 lines
3.6 KiB
C++
128 lines
3.6 KiB
C++
//=- llvm/CodeGen/ScoreboardHazardRecognizer.h - Schedule Support -*- C++ -*-=//
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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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//
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// This file defines the ScoreboardHazardRecognizer class, which
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// encapsulates hazard-avoidance heuristics for scheduling, based on the
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// scheduling itineraries specified for the target.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CODEGEN_SCOREBOARDHAZARDRECOGNIZER_H
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#define LLVM_CODEGEN_SCOREBOARDHAZARDRECOGNIZER_H
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#include "llvm/CodeGen/ScheduleHazardRecognizer.h"
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#include <cassert>
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#include <cstddef>
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#include <cstring>
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namespace llvm {
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class InstrItineraryData;
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class ScheduleDAG;
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class SUnit;
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class ScoreboardHazardRecognizer : public ScheduleHazardRecognizer {
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// Scoreboard to track function unit usage. Scoreboard[0] is a
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// mask of the FUs in use in the cycle currently being
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// schedule. Scoreboard[1] is a mask for the next cycle. The
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// Scoreboard is used as a circular buffer with the current cycle
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// indicated by Head.
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//
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// Scoreboard always counts cycles in forward execution order. If used by a
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// bottom-up scheduler, then the scoreboard cycles are the inverse of the
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// scheduler's cycles.
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class Scoreboard {
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unsigned *Data = nullptr;
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// The maximum number of cycles monitored by the Scoreboard. This
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// value is determined based on the target itineraries to ensure
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// that all hazards can be tracked.
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size_t Depth = 0;
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// Indices into the Scoreboard that represent the current cycle.
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size_t Head = 0;
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public:
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Scoreboard() = default;
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~Scoreboard() {
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delete[] Data;
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}
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size_t getDepth() const { return Depth; }
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unsigned& operator[](size_t idx) const {
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// Depth is expected to be a power-of-2.
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assert(Depth && !(Depth & (Depth - 1)) &&
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"Scoreboard was not initialized properly!");
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return Data[(Head + idx) & (Depth-1)];
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}
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void reset(size_t d = 1) {
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if (!Data) {
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Depth = d;
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Data = new unsigned[Depth];
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}
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memset(Data, 0, Depth * sizeof(Data[0]));
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Head = 0;
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}
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void advance() {
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Head = (Head + 1) & (Depth-1);
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}
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void recede() {
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Head = (Head - 1) & (Depth-1);
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}
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// Print the scoreboard.
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void dump() const;
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};
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// Support for tracing ScoreboardHazardRecognizer as a component within
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// another module.
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const char *DebugType;
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// Itinerary data for the target.
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const InstrItineraryData *ItinData;
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const ScheduleDAG *DAG;
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/// IssueWidth - Max issue per cycle. 0=Unknown.
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unsigned IssueWidth = 0;
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/// IssueCount - Count instructions issued in this cycle.
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unsigned IssueCount = 0;
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Scoreboard ReservedScoreboard;
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Scoreboard RequiredScoreboard;
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public:
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ScoreboardHazardRecognizer(const InstrItineraryData *II,
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const ScheduleDAG *DAG,
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const char *ParentDebugType = "");
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/// atIssueLimit - Return true if no more instructions may be issued in this
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/// cycle.
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bool atIssueLimit() const override;
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// Stalls provides an cycle offset at which SU will be scheduled. It will be
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// negative for bottom-up scheduling.
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HazardType getHazardType(SUnit *SU, int Stalls) override;
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void Reset() override;
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void EmitInstruction(SUnit *SU) override;
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void AdvanceCycle() override;
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void RecedeCycle() override;
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};
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} // end namespace llvm
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#endif // LLVM_CODEGEN_SCOREBOARDHAZARDRECOGNIZER_H
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