llvm-6502/lib/Target/PowerPC/PPCHazardRecognizers.h
Hal Finkel f0c1388dd1 Improve instruction scheduling for the PPC POWER7
Aside from a few minor latency corrections, the major change here is a new
hazard recognizer which focuses on better dispatch-group formation on the
POWER7. As with the PPC970's hazard recognizer, the most important thing it
does is avoid load-after-store hazards within the same dispatch group. It uses
the POWER7's special dispatch-group-terminating nop instruction (instead of
inserting multiple regular nop instructions). This new hazard recognizer makes
use of the scheduling dependency graph itself, built using AA information, to
robustly detect the possibility of load-after-store hazards.

significant test-suite performance changes (the error bars are 99.5% confidence
intervals based on 5 test-suite runs both with and without the change --
speedups are negative):

speedups:

MultiSource/Benchmarks/FreeBench/pcompress2/pcompress2
	-0.55171% +/- 0.333168%

MultiSource/Benchmarks/TSVC/CrossingThresholds-dbl/CrossingThresholds-dbl
	-17.5576% +/- 14.598%

MultiSource/Benchmarks/TSVC/Reductions-dbl/Reductions-dbl
	-29.5708% +/- 7.09058%

MultiSource/Benchmarks/TSVC/Reductions-flt/Reductions-flt
	-34.9471% +/- 11.4391%

SingleSource/Benchmarks/BenchmarkGame/puzzle
	-25.1347% +/- 11.0104%

SingleSource/Benchmarks/Misc/flops-8
	-17.7297% +/- 9.79061%

SingleSource/Benchmarks/Shootout-C++/ary3
	-35.5018% +/- 23.9458%

SingleSource/Regression/C/uint64_to_float
	-56.3165% +/- 25.4234%

SingleSource/UnitTests/Vectorizer/gcc-loops
	-18.5309% +/- 6.8496%

regressions:

MultiSource/Benchmarks/ASCI_Purple/SMG2000/smg2000
	18.351% +/- 12.156%

SingleSource/Benchmarks/Shootout-C++/methcall
	27.3086% +/- 14.4733%

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197099 91177308-0d34-0410-b5e6-96231b3b80d8
2013-12-12 00:19:11 +00:00

103 lines
3.7 KiB
C++

//===-- PPCHazardRecognizers.h - PowerPC Hazard Recognizers -----*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines hazard recognizers for scheduling on PowerPC processors.
//
//===----------------------------------------------------------------------===//
#ifndef PPCHAZRECS_H
#define PPCHAZRECS_H
#include "PPCInstrInfo.h"
#include "llvm/CodeGen/ScheduleHazardRecognizer.h"
#include "llvm/CodeGen/ScoreboardHazardRecognizer.h"
#include "llvm/CodeGen/SelectionDAGNodes.h"
namespace llvm {
/// PPCDispatchGroupSBHazardRecognizer - This class implements a scoreboard-based
/// hazard recognizer for PPC ooo processors with dispatch-group hazards.
class PPCDispatchGroupSBHazardRecognizer : public ScoreboardHazardRecognizer {
const ScheduleDAG *DAG;
SmallVector<SUnit *, 7> CurGroup;
unsigned CurSlots, CurBranches;
bool isLoadAfterStore(SUnit *SU);
bool isBCTRAfterSet(SUnit *SU);
bool mustComeFirst(const MCInstrDesc *MCID, unsigned &NSlots);
public:
PPCDispatchGroupSBHazardRecognizer(const InstrItineraryData *ItinData,
const ScheduleDAG *DAG_) :
ScoreboardHazardRecognizer(ItinData, DAG_), DAG(DAG_),
CurSlots(0), CurBranches(0) {}
virtual HazardType getHazardType(SUnit *SU, int Stalls);
virtual bool ShouldPreferAnother(SUnit* SU);
virtual unsigned PreEmitNoops(SUnit *SU);
virtual void EmitInstruction(SUnit *SU);
virtual void AdvanceCycle();
virtual void RecedeCycle();
virtual void Reset();
virtual void EmitNoop();
};
/// PPCHazardRecognizer970 - This class defines a finite state automata that
/// models the dispatch logic on the PowerPC 970 (aka G5) processor. This
/// promotes good dispatch group formation and implements noop insertion to
/// avoid structural hazards that cause significant performance penalties (e.g.
/// setting the CTR register then branching through it within a dispatch group),
/// or storing then loading from the same address within a dispatch group.
class PPCHazardRecognizer970 : public ScheduleHazardRecognizer {
const TargetMachine &TM;
unsigned NumIssued; // Number of insts issued, including advanced cycles.
// Various things that can cause a structural hazard.
// HasCTRSet - If the CTR register is set in this group, disallow BCTRL.
bool HasCTRSet;
// StoredPtr - Keep track of the address of any store. If we see a load from
// the same address (or one that aliases it), disallow the store. We can have
// up to four stores in one dispatch group, hence we track up to 4.
//
// This is null if we haven't seen a store yet. We keep track of both
// operands of the store here, since we support [r+r] and [r+i] addressing.
const Value *StoreValue[4];
int64_t StoreOffset[4];
uint64_t StoreSize[4];
unsigned NumStores;
public:
PPCHazardRecognizer970(const TargetMachine &TM);
virtual HazardType getHazardType(SUnit *SU, int Stalls);
virtual void EmitInstruction(SUnit *SU);
virtual void AdvanceCycle();
virtual void Reset();
private:
/// EndDispatchGroup - Called when we are finishing a new dispatch group.
///
void EndDispatchGroup();
/// GetInstrType - Classify the specified powerpc opcode according to its
/// pipeline.
PPCII::PPC970_Unit GetInstrType(unsigned Opcode,
bool &isFirst, bool &isSingle,bool &isCracked,
bool &isLoad, bool &isStore);
bool isLoadOfStoredAddress(uint64_t LoadSize, int64_t LoadOffset,
const Value *LoadValue) const;
};
} // end namespace llvm
#endif