#include <MCInstrItineraries.h>

Collaboration diagram for llvm::InstrStage:

Public Types
enum	ReservationKinds { Required = 0, Reserved = 1 }

Public Member Functions
unsigned	getCycles () const
	getCycles - returns the number of cycles the stage is occupied More...

unsigned	getUnits () const
	getUnits - returns the choice of FUs More...

ReservationKinds	getReservationKind () const

unsigned	getNextCycles () const

Public Attributes
unsigned	Cycles_
	Length of stage in machine cycles. More...

unsigned	Units_
	Choice of functional units. More...

int	NextCycles_
	Number of machine cycles to next stage. More...

ReservationKinds	Kind_
	Kind of the FU reservation. More...

Detailed Description

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.

Definition at line 59 of file MCInstrItineraries.h.