David Goodwin | d94a4e5 | 2009-08-10 15:55:25 +0000 | [diff] [blame] | 1 | //=- llvm/CodeGen/SimpleHazardRecognizer.h - Scheduling Support -*- C++ -*-=// |
| 2 | // |
| 3 | // The LLVM Compiler Infrastructure |
| 4 | // |
| 5 | // This file is distributed under the University of Illinois Open Source |
| 6 | // License. See LICENSE.TXT for details. |
| 7 | // |
| 8 | //===----------------------------------------------------------------------===// |
| 9 | // |
| 10 | // This file implements the SimpleHazardRecognizer class, which |
| 11 | // implements hazard-avoidance heuristics for scheduling, based on the |
| 12 | // scheduling itineraries specified for the target. |
| 13 | // |
| 14 | //===----------------------------------------------------------------------===// |
| 15 | |
| 16 | #ifndef LLVM_CODEGEN_SIMPLEHAZARDRECOGNIZER_H |
| 17 | #define LLVM_CODEGEN_SIMPLEHAZARDRECOGNIZER_H |
| 18 | |
| 19 | #include "llvm/CodeGen/ScheduleHazardRecognizer.h" |
| 20 | #include "llvm/CodeGen/ScheduleDAG.h" |
| 21 | #include "llvm/Target/TargetMachine.h" |
| 22 | #include "llvm/Target/TargetInstrInfo.h" |
| 23 | |
| 24 | namespace llvm { |
| 25 | /// SimpleHazardRecognizer - A *very* simple hazard recognizer. It uses |
| 26 | /// a coarse classification and attempts to avoid that instructions of |
| 27 | /// a given class aren't grouped too densely together. |
| 28 | class SimpleHazardRecognizer : public ScheduleHazardRecognizer { |
| 29 | /// Class - A simple classification for SUnits. |
| 30 | enum Class { |
| 31 | Other, Load, Store |
| 32 | }; |
| 33 | |
| 34 | /// Window - The Class values of the most recently issued |
| 35 | /// instructions. |
| 36 | Class Window[8]; |
| 37 | |
| 38 | /// getClass - Classify the given SUnit. |
| 39 | Class getClass(const SUnit *SU) { |
| 40 | const MachineInstr *MI = SU->getInstr(); |
| 41 | const TargetInstrDesc &TID = MI->getDesc(); |
| 42 | if (TID.mayLoad()) |
| 43 | return Load; |
| 44 | if (TID.mayStore()) |
| 45 | return Store; |
| 46 | return Other; |
| 47 | } |
| 48 | |
| 49 | /// Step - Rotate the existing entries in Window and insert the |
| 50 | /// given class value in position as the most recent. |
| 51 | void Step(Class C) { |
| 52 | std::copy(Window+1, array_endof(Window), Window); |
| 53 | Window[array_lengthof(Window)-1] = C; |
| 54 | } |
| 55 | |
| 56 | public: |
| 57 | SimpleHazardRecognizer() : Window() { |
| 58 | Reset(); |
| 59 | } |
| 60 | |
| 61 | virtual HazardType getHazardType(SUnit *SU) { |
| 62 | Class C = getClass(SU); |
| 63 | if (C == Other) |
| 64 | return NoHazard; |
| 65 | unsigned Score = 0; |
| 66 | for (unsigned i = 0; i != array_lengthof(Window); ++i) |
| 67 | if (Window[i] == C) |
| 68 | Score += i + 1; |
| 69 | if (Score > array_lengthof(Window) * 2) |
| 70 | return Hazard; |
| 71 | return NoHazard; |
| 72 | } |
| 73 | |
| 74 | virtual void Reset() { |
| 75 | for (unsigned i = 0; i != array_lengthof(Window); ++i) |
| 76 | Window[i] = Other; |
| 77 | } |
| 78 | |
| 79 | virtual void EmitInstruction(SUnit *SU) { |
| 80 | Step(getClass(SU)); |
| 81 | } |
| 82 | |
| 83 | virtual void AdvanceCycle() { |
| 84 | Step(Other); |
| 85 | } |
| 86 | }; |
| 87 | } |
| 88 | |
| 89 | #endif |