llvm/llvm/lib/Target/PowerPC/PPCHazardRecognizers.cpp

//===-- PPCHazardRecognizers.cpp - PowerPC Hazard Recognizer Impls --------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements hazard recognizers for scheduling on PowerPC processors.
//
//===----------------------------------------------------------------------===//

#include "PPCHazardRecognizers.h"
#include "PPCInstrInfo.h"
#include "PPCSubtarget.h"
#include "llvm/CodeGen/ScheduleDAG.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
usingnamespacellvm;

#define DEBUG_TYPE …

bool PPCDispatchGroupSBHazardRecognizer::isLoadAfterStore(SUnit *SU) { … }

bool PPCDispatchGroupSBHazardRecognizer::isBCTRAfterSet(SUnit *SU) { … }

// FIXME: Remove this when we don't need this:
namespace llvm { namespace PPC { extern int getNonRecordFormOpcode(uint16_t); } }

// FIXME: A lot of code in PPCDispatchGroupSBHazardRecognizer is P7 specific.

bool PPCDispatchGroupSBHazardRecognizer::mustComeFirst(const MCInstrDesc *MCID,
                                                       unsigned &NSlots) { … }

ScheduleHazardRecognizer::HazardType
PPCDispatchGroupSBHazardRecognizer::getHazardType(SUnit *SU, int Stalls) { … }

bool PPCDispatchGroupSBHazardRecognizer::ShouldPreferAnother(SUnit *SU) { … }

unsigned PPCDispatchGroupSBHazardRecognizer::PreEmitNoops(SUnit *SU) { … }

void PPCDispatchGroupSBHazardRecognizer::EmitInstruction(SUnit *SU) { … }

void PPCDispatchGroupSBHazardRecognizer::AdvanceCycle() { … }

void PPCDispatchGroupSBHazardRecognizer::RecedeCycle() { … }

void PPCDispatchGroupSBHazardRecognizer::Reset() { … }

void PPCDispatchGroupSBHazardRecognizer::EmitNoop() { … }

//===----------------------------------------------------------------------===//
// PowerPC 970 Hazard Recognizer
//
// This models the dispatch group formation of the PPC970 processor.  Dispatch
// groups are bundles of up to five instructions that can contain various mixes
// of instructions.  The PPC970 can dispatch a peak of 4 non-branch and one
// branch instruction per-cycle.
//
// There are a number of restrictions to dispatch group formation: some
// instructions can only be issued in the first slot of a dispatch group, & some
// instructions fill an entire dispatch group.  Additionally, only branches can
// issue in the 5th (last) slot.
//
// Finally, there are a number of "structural" hazards on the PPC970.  These
// conditions cause large performance penalties due to misprediction, recovery,
// and replay logic that has to happen.  These cases include setting a CTR and
// branching through it in the same dispatch group, and storing to an address,
// then loading from the same address within a dispatch group.  To avoid these
// conditions, we insert no-op instructions when appropriate.
//
// FIXME: This is missing some significant cases:
//   1. Modeling of microcoded instructions.
//   2. Handling of serialized operations.
//   3. Handling of the esoteric cases in "Resource-based Instruction Grouping".
//

PPCHazardRecognizer970::PPCHazardRecognizer970(const ScheduleDAG &DAG)
    : … { … }

void PPCHazardRecognizer970::EndDispatchGroup() { … }


PPCII::PPC970_Unit
PPCHazardRecognizer970::GetInstrType(unsigned Opcode,
                                     bool &isFirst, bool &isSingle,
                                     bool &isCracked,
                                     bool &isLoad, bool &isStore) { … }

/// isLoadOfStoredAddress - If we have a load from the previously stored pointer
/// as indicated by StorePtr1/StorePtr2/StoreSize, return true.
bool PPCHazardRecognizer970::
isLoadOfStoredAddress(uint64_t LoadSize, int64_t LoadOffset,
  const Value *LoadValue) const { … }

/// getHazardType - We return hazard for any non-branch instruction that would
/// terminate the dispatch group.  We turn NoopHazard for any
/// instructions that wouldn't terminate the dispatch group that would cause a
/// pipeline flush.
ScheduleHazardRecognizer::HazardType PPCHazardRecognizer970::
getHazardType(SUnit *SU, int Stalls) { … }

void PPCHazardRecognizer970::EmitInstruction(SUnit *SU) { … }

void PPCHazardRecognizer970::AdvanceCycle() { … }

void PPCHazardRecognizer970::Reset() { … }