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//===-- llvm/Target/TargetInstrItineraries.h - Scheduling -------*- C++ -*-===//
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// The LLVM Compiler Infrastructure
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//===----------------------------------------------------------------------===//
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// This file describes the structures used for instruction
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// itineraries, stages, and operand reads/writes. This is used by
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// schedulers to determine instruction stages and latencies.
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_TARGET_TARGETINSTRITINERARIES_H
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#define LLVM_TARGET_TARGETINSTRITINERARIES_H
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//===----------------------------------------------------------------------===//
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/// Instruction stage - These values represent a non-pipelined step in
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/// the execution of an instruction. Cycles represents the number of
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/// discrete time slots needed to complete the stage. Units represent
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/// the choice of functional units that can be used to complete the
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/// stage. Eg. IntUnit1, IntUnit2. NextCycles indicates how many
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/// cycles should elapse from the start of this stage to the start of
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/// the next stage in the itinerary. A value of -1 indicates that the
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/// next stage should start immediately after the current one.
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/// indicates that the stage occupies FU x for 1 cycle and that
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/// the next stage starts immediately after this one.
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/// indicates that the stage occupies either FU x or FU y for 2
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/// consecuative cycles and that the next stage starts one cycle
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/// after this stage starts. That is, the stage requirements
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/// indicates that the stage occupies FU x for 1 cycle and that
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/// the next stage starts in this same cycle. This can be used to
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/// indicate that the instruction requires multiple stages at the
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/// FU reservation can be of two different kinds:
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/// - FUs which instruction actually requires
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/// - FUs which instruction just reserves. Reserved unit is not available for
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/// execution of other instruction. However, several instructions can reserve
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/// the same unit several times.
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/// Such two types of units reservation is used to model instruction domain
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/// change stalls, FUs using the same resource (e.g. same register file), etc.
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enum ReservationKinds {
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unsigned Cycles_; ///< Length of stage in machine cycles
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unsigned Units_; ///< Choice of functional units
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int NextCycles_; ///< Number of machine cycles to next stage
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ReservationKinds Kind_; ///< Kind of the FU reservation
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/// getCycles - returns the number of cycles the stage is occupied
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unsigned getCycles() const {
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/// getUnits - returns the choice of FUs
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unsigned getUnits() const {
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ReservationKinds getReservationKind() const {
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/// getNextCycles - returns the number of cycles from the start of
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/// this stage to the start of the next stage in the itinerary
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unsigned getNextCycles() const {
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return (NextCycles_ >= 0) ? (unsigned)NextCycles_ : Cycles_;
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//===----------------------------------------------------------------------===//
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/// Instruction itinerary - An itinerary represents the scheduling
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/// information for an instruction. This includes a set of stages
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/// occupies by the instruction, and the pipeline cycle in which
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/// operands are read and written.
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struct InstrItinerary {
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unsigned FirstStage; ///< Index of first stage in itinerary
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unsigned LastStage; ///< Index of last + 1 stage in itinerary
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unsigned FirstOperandCycle; ///< Index of first operand rd/wr
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unsigned LastOperandCycle; ///< Index of last + 1 operand rd/wr
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//===----------------------------------------------------------------------===//
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/// Instruction itinerary Data - Itinerary data supplied by a subtarget to be
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/// used by a target.
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class InstrItineraryData {
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const InstrStage *Stages; ///< Array of stages selected
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const unsigned *OperandCycles; ///< Array of operand cycles selected
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const InstrItinerary *Itineratries; ///< Array of itineraries selected
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InstrItineraryData() : Stages(0), OperandCycles(0), Itineratries(0) {}
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InstrItineraryData(const InstrStage *S, const unsigned *OS,
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const InstrItinerary *I)
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: Stages(S), OperandCycles(OS), Itineratries(I) {}
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/// isEmpty - Returns true if there are no itineraries.
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bool isEmpty() const { return Itineratries == 0; }
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/// isEndMarker - Returns true if the index is for the end marker
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bool isEndMarker(unsigned ItinClassIndx) const {
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return ((Itineratries[ItinClassIndx].FirstStage == ~0U) &&
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(Itineratries[ItinClassIndx].LastStage == ~0U));
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/// beginStage - Return the first stage of the itinerary.
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const InstrStage *beginStage(unsigned ItinClassIndx) const {
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unsigned StageIdx = Itineratries[ItinClassIndx].FirstStage;
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return Stages + StageIdx;
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/// endStage - Return the last+1 stage of the itinerary.
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const InstrStage *endStage(unsigned ItinClassIndx) const {
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unsigned StageIdx = Itineratries[ItinClassIndx].LastStage;
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return Stages + StageIdx;
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/// getStageLatency - Return the total stage latency of the given
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/// class. The latency is the maximum completion time for any stage
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/// in the itinerary.
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unsigned getStageLatency(unsigned ItinClassIndx) const {
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// If the target doesn't provide itinerary information, use a
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// simple non-zero default value for all instructions.
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// Calculate the maximum completion time for any stage.
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unsigned Latency = 0, StartCycle = 0;
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for (const InstrStage *IS = beginStage(ItinClassIndx),
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*E = endStage(ItinClassIndx); IS != E; ++IS) {
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Latency = std::max(Latency, StartCycle + IS->getCycles());
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StartCycle += IS->getNextCycles();
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/// getOperandCycle - Return the cycle for the given class and
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/// operand. Return -1 if no cycle is specified for the operand.
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int getOperandCycle(unsigned ItinClassIndx, unsigned OperandIdx) const {
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unsigned FirstIdx = Itineratries[ItinClassIndx].FirstOperandCycle;
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unsigned LastIdx = Itineratries[ItinClassIndx].LastOperandCycle;
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if ((FirstIdx + OperandIdx) >= LastIdx)
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return (int)OperandCycles[FirstIdx + OperandIdx];
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} // End llvm namespace