org.jikesrvm.compilers.opt.regalloc.ia32

Class ExpandFPRStackConvention

java.lang.Object

org.jikesrvm.compilers.opt.driver.CompilerPhase

org.jikesrvm.compilers.opt.regalloc.ia32.ExpandFPRStackConvention

public final class ExpandFPRStackConvention
extends CompilerPhase

At the beginning of each basic block, the register allocator expects all floating-point stack locations to be available, and named FPi, 0 < i < 7

However, BURS may consume FP stack locations by inserting instructions that push or pop the floating-point stack. This phase inserts dummy definitions and uses to indicate when symbolic FP registers are not available for register allocation since BURS has consumed a stack slot. For example,

    FLD t1
    ...
    FSTP M, t1
 

will be modified by this phase to indicate that FP6 is not available for allocation in the interval:

   DUMMY_DEF FP6
   FLD t1
   .....
   FSTP M, t1
   DUMMY_USE FP6
 

Additionally, by convention, we will always clear the floating-point stack when delivering an exception. To model this, we insert dummy defs and uses for each floating-point register at the beginning of each catch block.

Field Summary

Fields

Modifier and Type	Field and Description
private static int	NUM_ALLOCATABLE_FPR The number of FPRs available for allocation.

Fields inherited from class org.jikesrvm.compilers.opt.driver.CompilerPhase

container

Constructor Summary

Constructors

Constructor and Description
ExpandFPRStackConvention()

Method Summary

Modifier and Type	Method and Description
String	getName()
CompilerPhase	newExecution(IR ir) Return this instance of this phase.
void	perform(IR ir) Insert the needed dummy defs and uses.
boolean	printingEnabled(OptOptions options, boolean before) Returns true if the phase wants the IR dumped before and/or after it runs.

Methods inherited from class org.jikesrvm.compilers.opt.driver.CompilerPhase

dumpIR, dumpIR, getClassConstructor, getCompilerPhaseConstructor, getCompilerPhaseConstructor, performPhase, reportAdditionalStats, setContainer, shouldPerform, verify

Methods inherited from class java.lang.Object

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

Field Detail

NUM_ALLOCATABLE_FPR

private static final int NUM_ALLOCATABLE_FPR

The number of FPRs available for allocation. Normally 7: we reserve one for final MIR expansion.

See Also:

Constant Field Values

Constructor Detail

ExpandFPRStackConvention

public ExpandFPRStackConvention()

Method Detail

newExecution

public CompilerPhase newExecution(IR ir)

Return this instance of this phase. This phase contains no per-compilation instance fields.

Overrides:

newExecution in class CompilerPhase

Parameters:

ir - not used

Returns:

this

printingEnabled

public boolean printingEnabled(OptOptions options,
                               boolean before)

Description copied from class: CompilerPhase

Returns true if the phase wants the IR dumped before and/or after it runs. By default, printing is not enabled. Subclasses should override this method if they want to provide IR dumping.

Overrides:

printingEnabled in class CompilerPhase

Parameters:

options - the compiler options for the compilation

before - true when invoked before perform, false otherwise.

Returns:

true if the IR should be printed, false otherwise.

getName

public String getName()

Specified by:

getName in class CompilerPhase

Returns:

a String which is the name of the phase.

perform

public void perform(IR ir)

Insert the needed dummy defs and uses.

Specified by:

perform in class CompilerPhase

Parameters:

ir - the IR on which to apply the phase