scale.backend
Class BBIS

java.lang.Object
  scale.backend.BBIS

public class BBIS
extends java.lang.Object

This class provides basic block instruction scheduling.

$Id: BBIS.java,v 1.15 2007-10-04 19:57:48 burrill Exp $

Copyright 2008 by the Scale Compiler Group,
Department of Computer Science
University of Massachusetts,
Amherst MA. 01003, USA
All Rights Reserved.

The basic organization for this instruction scheduler was inspired by Chapter 12 of "Engineering a Compiler" by Keith D. Cooper and Linda Torczon, Morgan Kaufman Publishers, ISBN: 1-55860-698-X.

The basic list scheduling algorithm is used. Both forward and backward list scheduling are tried for each basic block to obtain the best schedule. The scheduler picks the priority scheme used to select the next instruction based on metrics of the basic block.

Anit-dependencies are handled without renaming. When the scheduler is run prior to rgister allocation very little renaming is required. When run after register allocation, renaming cannot be used.

The schuler requires two pieces on information from each instruction in addition to the registers used or def-ed by the instruction.

1. The length of time the instruction takes to execute in cycles.
2. The type of instruction - that is the functional unit that will execute it.

The scheduler will ask the code generator for the number of functional units that are available for a given type.

To add a different instruction scheduler, derive it from this class and implement the schedule() method. Then modify the code generator to use the new instruction scheduler.

Field Summary

static boolean	all True if all functions should be scheduled - false if just traced functions should be scheduled.
static boolean	classTrace True if traces are to be performed.
protected Generator	gen
static int	max Maximum block size to be scheduled.
static int	min Minimum block size to be scheduled.
protected RegisterSet	registers

Constructor Summary

BBIS(Generator gen)

Method Summary

Instruction

schedule(Instruction insts, boolean trace) Schedule all the instructions in a function.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

classTrace

public static boolean classTrace

True if traces are to be performed.

all

public static boolean all

True if all functions should be scheduled - false if just traced functions should be scheduled.

min

public static int min

Minimum block size to be scheduled.

max

public static int max

Maximum block size to be scheduled.

gen

protected Generator gen

registers

protected RegisterSet registers

Constructor Detail

BBIS

public BBIS(Generator gen)

Method Detail

schedule

public Instruction schedule(Instruction insts,
                            boolean trace)

Schedule all the instructions in a function.

Parameters:

insts - is the list of instructions

Returns:

the list of instructions in scheduled order