90 lines
2.6 KiB
C++
90 lines
2.6 KiB
C++
//=- llvm/CodeGen/SimpleHazardRecognizer.h - Scheduling Support -*- C++ -*-=//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the SimpleHazardRecognizer class, which
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// implements 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_SIMPLEHAZARDRECOGNIZER_H
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#define LLVM_CODEGEN_SIMPLEHAZARDRECOGNIZER_H
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#include "llvm/CodeGen/ScheduleHazardRecognizer.h"
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#include "llvm/CodeGen/ScheduleDAG.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Target/TargetInstrInfo.h"
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namespace llvm {
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/// SimpleHazardRecognizer - A *very* simple hazard recognizer. It uses
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/// a coarse classification and attempts to avoid that instructions of
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/// a given class aren't grouped too densely together.
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class SimpleHazardRecognizer : public ScheduleHazardRecognizer {
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/// Class - A simple classification for SUnits.
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enum Class {
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Other, Load, Store
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};
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/// Window - The Class values of the most recently issued
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/// instructions.
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Class Window[8];
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/// getClass - Classify the given SUnit.
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Class getClass(const SUnit *SU) {
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const MachineInstr *MI = SU->getInstr();
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const TargetInstrDesc &TID = MI->getDesc();
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if (TID.mayLoad())
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return Load;
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if (TID.mayStore())
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return Store;
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return Other;
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}
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/// Step - Rotate the existing entries in Window and insert the
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/// given class value in position as the most recent.
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void Step(Class C) {
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std::copy(Window+1, array_endof(Window), Window);
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Window[array_lengthof(Window)-1] = C;
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}
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public:
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SimpleHazardRecognizer() : Window() {
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Reset();
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}
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virtual HazardType getHazardType(SUnit *SU) {
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Class C = getClass(SU);
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if (C == Other)
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return NoHazard;
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unsigned Score = 0;
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for (unsigned i = 0; i != array_lengthof(Window); ++i)
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if (Window[i] == C)
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Score += i + 1;
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if (Score > array_lengthof(Window) * 2)
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return Hazard;
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return NoHazard;
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}
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virtual void Reset() {
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for (unsigned i = 0; i != array_lengthof(Window); ++i)
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Window[i] = Other;
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}
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virtual void EmitInstruction(SUnit *SU) {
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Step(getClass(SU));
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}
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virtual void AdvanceCycle() {
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Step(Other);
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}
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};
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}
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#endif
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