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llvm-mirror/lib/Target/PowerPC/PPCHazardRecognizers.h
Hal Finkel 548d6f1ad0 Fix dynamic linking on PPC64.
Dynamic linking on PPC64 has had problems since we had to move the top-down
hazard-detection logic post-ra. For dynamic linking to work there needs to be
a nop placed after every call. It turns out that it is really hard to guarantee
that nothing will be placed in between the call (bl) and the nop during post-ra
scheduling. Previous attempts at fixing this by placing logic inside the
hazard detector only partially worked.

This is now fixed in a different way: call+nop codegen-only instructions. As far
as CodeGen is concerned the pair is now a single instruction and cannot be split.
This solution works much better than previous attempts.

The scoreboard hazard detector is also renamed to be more generic, there is currently
no cpu-specific logic in it.

llvm-svn: 153816
2012-03-31 14:45:15 +00:00

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3.3 KiB
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//===-- 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 {
/// PPCScoreboardHazardRecognizer - This class implements a scoreboard-based
/// hazard recognizer for generic PPC processors.
class PPCScoreboardHazardRecognizer : public ScoreboardHazardRecognizer {
const ScheduleDAG *DAG;
public:
PPCScoreboardHazardRecognizer(const InstrItineraryData *ItinData,
const ScheduleDAG *DAG_) :
ScoreboardHazardRecognizer(ItinData, DAG_), DAG(DAG_) {}
virtual HazardType getHazardType(SUnit *SU, int Stalls);
virtual void EmitInstruction(SUnit *SU);
virtual void AdvanceCycle();
virtual void Reset();
};
/// 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 TargetInstrInfo &TII;
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 TargetInstrInfo &TII);
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