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72 lines
2.5 KiB
C++
72 lines
2.5 KiB
C++
//=- llvm/CodeGen/ScheduleHazardRecognizer.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 ScheduleHazardRecognizer class, which implements
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// hazard-avoidance heuristics for scheduling.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CODEGEN_SCHEDULEHAZARDRECOGNIZER_H
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#define LLVM_CODEGEN_SCHEDULEHAZARDRECOGNIZER_H
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namespace llvm {
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class SUnit;
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/// HazardRecognizer - This determines whether or not an instruction can be
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/// issued this cycle, and whether or not a noop needs to be inserted to handle
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/// the hazard.
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class ScheduleHazardRecognizer {
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public:
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virtual ~ScheduleHazardRecognizer();
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enum HazardType {
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NoHazard, // This instruction can be emitted at this cycle.
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Hazard, // This instruction can't be emitted at this cycle.
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NoopHazard // This instruction can't be emitted, and needs noops.
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};
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/// getHazardType - Return the hazard type of emitting this node. There are
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/// three possible results. Either:
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/// * NoHazard: it is legal to issue this instruction on this cycle.
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/// * Hazard: issuing this instruction would stall the machine. If some
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/// other instruction is available, issue it first.
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/// * NoopHazard: issuing this instruction would break the program. If
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/// some other instruction can be issued, do so, otherwise issue a noop.
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virtual HazardType getHazardType(SUnit *) {
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return NoHazard;
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}
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/// Reset - This callback is invoked when a new block of
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/// instructions is about to be schedule. The hazard state should be
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/// set to an initialized state.
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virtual void Reset() {}
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/// EmitInstruction - This callback is invoked when an instruction is
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/// emitted, to advance the hazard state.
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virtual void EmitInstruction(SUnit *) {}
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/// AdvanceCycle - This callback is invoked when no instructions can be
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/// issued on this cycle without a hazard. This should increment the
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/// internal state of the hazard recognizer so that previously "Hazard"
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/// instructions will now not be hazards.
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virtual void AdvanceCycle() {}
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/// EmitNoop - This callback is invoked when a noop was added to the
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/// instruction stream.
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virtual void EmitNoop() {
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// Default implementation: count it as a cycle.
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AdvanceCycle();
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}
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};
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}
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#endif
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