llvm-6502/include/llvm/MC/MCInstrItineraries.h
Pete Cooper 6de6c6aae4 Change MCSchedModel to be a struct of statically initialized data.
This removes static initializers from the backends which generate this data, and also makes this struct match the other Tablegen generated structs in behaviour

Reviewed by Andy Trick and Chandler C

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216919 91177308-0d34-0410-b5e6-96231b3b80d8
2014-09-02 17:43:54 +00:00

252 lines
9.3 KiB
C++

//===-- llvm/MC/MCInstrItineraries.h - Scheduling ---------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file describes the structures used for instruction
// itineraries, stages, and operand reads/writes. This is used by
// schedulers to determine instruction stages and latencies.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_MC_MCINSTRITINERARIES_H
#define LLVM_MC_MCINSTRITINERARIES_H
#include "llvm/MC/MCSchedule.h"
#include <algorithm>
namespace llvm {
//===----------------------------------------------------------------------===//
/// Instruction stage - These values represent a non-pipelined step in
/// the execution of an instruction. Cycles represents the number of
/// discrete time slots needed to complete the stage. Units represent
/// the choice of functional units that can be used to complete the
/// stage. Eg. IntUnit1, IntUnit2. NextCycles indicates how many
/// cycles should elapse from the start of this stage to the start of
/// the next stage in the itinerary. A value of -1 indicates that the
/// next stage should start immediately after the current one.
/// For example:
///
/// { 1, x, -1 }
/// indicates that the stage occupies FU x for 1 cycle and that
/// the next stage starts immediately after this one.
///
/// { 2, x|y, 1 }
/// indicates that the stage occupies either FU x or FU y for 2
/// consecuative cycles and that the next stage starts one cycle
/// after this stage starts. That is, the stage requirements
/// overlap in time.
///
/// { 1, x, 0 }
/// indicates that the stage occupies FU x for 1 cycle and that
/// the next stage starts in this same cycle. This can be used to
/// indicate that the instruction requires multiple stages at the
/// same time.
///
/// FU reservation can be of two different kinds:
/// - FUs which instruction actually requires
/// - FUs which instruction just reserves. Reserved unit is not available for
/// execution of other instruction. However, several instructions can reserve
/// the same unit several times.
/// Such two types of units reservation is used to model instruction domain
/// change stalls, FUs using the same resource (e.g. same register file), etc.
struct InstrStage {
enum ReservationKinds {
Required = 0,
Reserved = 1
};
unsigned Cycles_; ///< Length of stage in machine cycles
unsigned Units_; ///< Choice of functional units
int NextCycles_; ///< Number of machine cycles to next stage
ReservationKinds Kind_; ///< Kind of the FU reservation
/// getCycles - returns the number of cycles the stage is occupied
unsigned getCycles() const {
return Cycles_;
}
/// getUnits - returns the choice of FUs
unsigned getUnits() const {
return Units_;
}
ReservationKinds getReservationKind() const {
return Kind_;
}
/// getNextCycles - returns the number of cycles from the start of
/// this stage to the start of the next stage in the itinerary
unsigned getNextCycles() const {
return (NextCycles_ >= 0) ? (unsigned)NextCycles_ : Cycles_;
}
};
//===----------------------------------------------------------------------===//
/// Instruction itinerary - An itinerary represents the scheduling
/// information for an instruction. This includes a set of stages
/// occupies by the instruction, and the pipeline cycle in which
/// operands are read and written.
///
struct InstrItinerary {
int NumMicroOps; ///< # of micro-ops, -1 means it's variable
unsigned FirstStage; ///< Index of first stage in itinerary
unsigned LastStage; ///< Index of last + 1 stage in itinerary
unsigned FirstOperandCycle; ///< Index of first operand rd/wr
unsigned LastOperandCycle; ///< Index of last + 1 operand rd/wr
};
//===----------------------------------------------------------------------===//
/// Instruction itinerary Data - Itinerary data supplied by a subtarget to be
/// used by a target.
///
class InstrItineraryData {
public:
MCSchedModel SchedModel; ///< Basic machine properties.
const InstrStage *Stages; ///< Array of stages selected
const unsigned *OperandCycles; ///< Array of operand cycles selected
const unsigned *Forwardings; ///< Array of pipeline forwarding pathes
const InstrItinerary *Itineraries; ///< Array of itineraries selected
/// Ctors.
///
InstrItineraryData() : SchedModel(MCSchedModel::GetDefaultSchedModel()),
Stages(nullptr), OperandCycles(nullptr),
Forwardings(nullptr), Itineraries(nullptr) {}
InstrItineraryData(const MCSchedModel &SM, const InstrStage *S,
const unsigned *OS, const unsigned *F)
: SchedModel(SM), Stages(S), OperandCycles(OS), Forwardings(F),
Itineraries(SchedModel.InstrItineraries) {}
/// isEmpty - Returns true if there are no itineraries.
///
bool isEmpty() const { return Itineraries == nullptr; }
/// isEndMarker - Returns true if the index is for the end marker
/// itinerary.
///
bool isEndMarker(unsigned ItinClassIndx) const {
return ((Itineraries[ItinClassIndx].FirstStage == ~0U) &&
(Itineraries[ItinClassIndx].LastStage == ~0U));
}
/// beginStage - Return the first stage of the itinerary.
///
const InstrStage *beginStage(unsigned ItinClassIndx) const {
unsigned StageIdx = Itineraries[ItinClassIndx].FirstStage;
return Stages + StageIdx;
}
/// endStage - Return the last+1 stage of the itinerary.
///
const InstrStage *endStage(unsigned ItinClassIndx) const {
unsigned StageIdx = Itineraries[ItinClassIndx].LastStage;
return Stages + StageIdx;
}
/// getStageLatency - Return the total stage latency of the given
/// class. The latency is the maximum completion time for any stage
/// in the itinerary.
///
/// If no stages exist, it defaults to one cycle.
unsigned getStageLatency(unsigned ItinClassIndx) const {
// If the target doesn't provide itinerary information, use a simple
// non-zero default value for all instructions.
if (isEmpty())
return 1;
// Calculate the maximum completion time for any stage.
unsigned Latency = 0, StartCycle = 0;
for (const InstrStage *IS = beginStage(ItinClassIndx),
*E = endStage(ItinClassIndx); IS != E; ++IS) {
Latency = std::max(Latency, StartCycle + IS->getCycles());
StartCycle += IS->getNextCycles();
}
return Latency;
}
/// getOperandCycle - Return the cycle for the given class and
/// operand. Return -1 if no cycle is specified for the operand.
///
int getOperandCycle(unsigned ItinClassIndx, unsigned OperandIdx) const {
if (isEmpty())
return -1;
unsigned FirstIdx = Itineraries[ItinClassIndx].FirstOperandCycle;
unsigned LastIdx = Itineraries[ItinClassIndx].LastOperandCycle;
if ((FirstIdx + OperandIdx) >= LastIdx)
return -1;
return (int)OperandCycles[FirstIdx + OperandIdx];
}
/// hasPipelineForwarding - Return true if there is a pipeline forwarding
/// between instructions of itinerary classes DefClass and UseClasses so that
/// value produced by an instruction of itinerary class DefClass, operand
/// index DefIdx can be bypassed when it's read by an instruction of
/// itinerary class UseClass, operand index UseIdx.
bool hasPipelineForwarding(unsigned DefClass, unsigned DefIdx,
unsigned UseClass, unsigned UseIdx) const {
unsigned FirstDefIdx = Itineraries[DefClass].FirstOperandCycle;
unsigned LastDefIdx = Itineraries[DefClass].LastOperandCycle;
if ((FirstDefIdx + DefIdx) >= LastDefIdx)
return false;
if (Forwardings[FirstDefIdx + DefIdx] == 0)
return false;
unsigned FirstUseIdx = Itineraries[UseClass].FirstOperandCycle;
unsigned LastUseIdx = Itineraries[UseClass].LastOperandCycle;
if ((FirstUseIdx + UseIdx) >= LastUseIdx)
return false;
return Forwardings[FirstDefIdx + DefIdx] ==
Forwardings[FirstUseIdx + UseIdx];
}
/// getOperandLatency - Compute and return the use operand latency of a given
/// itinerary class and operand index if the value is produced by an
/// instruction of the specified itinerary class and def operand index.
int getOperandLatency(unsigned DefClass, unsigned DefIdx,
unsigned UseClass, unsigned UseIdx) const {
if (isEmpty())
return -1;
int DefCycle = getOperandCycle(DefClass, DefIdx);
if (DefCycle == -1)
return -1;
int UseCycle = getOperandCycle(UseClass, UseIdx);
if (UseCycle == -1)
return -1;
UseCycle = DefCycle - UseCycle + 1;
if (UseCycle > 0 &&
hasPipelineForwarding(DefClass, DefIdx, UseClass, UseIdx))
// FIXME: This assumes one cycle benefit for every pipeline forwarding.
--UseCycle;
return UseCycle;
}
/// getNumMicroOps - Return the number of micro-ops that the given class
/// decodes to. Return -1 for classes that require dynamic lookup via
/// TargetInstrInfo.
int getNumMicroOps(unsigned ItinClassIndx) const {
if (isEmpty())
return 1;
return Itineraries[ItinClassIndx].NumMicroOps;
}
};
} // End llvm namespace
#endif