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Diffstat (limited to 'include/llvm/CodeGen/ScheduleHazardRecognizer.h')
-rw-r--r-- | include/llvm/CodeGen/ScheduleHazardRecognizer.h | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/include/llvm/CodeGen/ScheduleHazardRecognizer.h b/include/llvm/CodeGen/ScheduleHazardRecognizer.h new file mode 100644 index 0000000000..09e3e88613 --- /dev/null +++ b/include/llvm/CodeGen/ScheduleHazardRecognizer.h @@ -0,0 +1,71 @@ +//=- llvm/CodeGen/ScheduleHazardRecognizer.h - Scheduling Support -*- C++ -*-=// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file implements the ScheduleHazardRecognizer class, which implements +// hazard-avoidance heuristics for scheduling. +// +//===----------------------------------------------------------------------===// + +#ifndef LLVM_CODEGEN_SCHEDULEHAZARDRECOGNIZER_H +#define LLVM_CODEGEN_SCHEDULEHAZARDRECOGNIZER_H + +namespace llvm { + +class SUnit; + +/// HazardRecognizer - This determines whether or not an instruction can be +/// issued this cycle, and whether or not a noop needs to be inserted to handle +/// the hazard. +class ScheduleHazardRecognizer { +public: + virtual ~ScheduleHazardRecognizer(); + + enum HazardType { + NoHazard, // This instruction can be emitted at this cycle. + Hazard, // This instruction can't be emitted at this cycle. + NoopHazard // This instruction can't be emitted, and needs noops. + }; + + /// getHazardType - Return the hazard type of emitting this node. There are + /// three possible results. Either: + /// * NoHazard: it is legal to issue this instruction on this cycle. + /// * Hazard: issuing this instruction would stall the machine. If some + /// other instruction is available, issue it first. + /// * NoopHazard: issuing this instruction would break the program. If + /// some other instruction can be issued, do so, otherwise issue a noop. + virtual HazardType getHazardType(SUnit *) { + return NoHazard; + } + + /// Reset - This callback is invoked when a new block of + /// instructions is about to be schedule. The hazard state should be + /// set to an initialized state. + virtual void Reset() {} + + /// EmitInstruction - This callback is invoked when an instruction is + /// emitted, to advance the hazard state. + virtual void EmitInstruction(SUnit *) {} + + /// AdvanceCycle - This callback is invoked when no instructions can be + /// issued on this cycle without a hazard. This should increment the + /// internal state of the hazard recognizer so that previously "Hazard" + /// instructions will now not be hazards. + virtual void AdvanceCycle() {} + + /// EmitNoop - This callback is invoked when a noop was added to the + /// instruction stream. + virtual void EmitNoop() { + // Default implementation: count it as a cycle. + AdvanceCycle(); + } +}; + +} + +#endif |