org.jikesrvm.compilers.opt.controlflow
Class BranchOptimizationDriver

java.lang.Object
  org.jikesrvm.compilers.opt.driver.CompilerPhase
      org.jikesrvm.compilers.opt.controlflow.BranchOptimizationDriver

Direct Known Subclasses:

BranchOptimizations, MIRBranchOptimizations

public abstract class BranchOptimizationDriver
extends CompilerPhase

IR level independent driver for simple peephole optimizations of branches.

level

private final int level

Optimization level at which phase should be performed.

simplify

private final boolean simplify

Optimization level at which phase should be performed.

BranchOptimizationDriver

BranchOptimizationDriver(int level,
                         boolean simplify)

Parameters:

level - the minimum optimization level at which the branch optimizations should be performed.

simplify - perform simplification prior to optimization?

BranchOptimizationDriver

BranchOptimizationDriver(int level)

Parameters:

level - the minimum optimization level at which the branch optimizations should be performed.

shouldPerform

public final boolean shouldPerform(OptOptions options)

Interface

Overrides:

shouldPerform in class CompilerPhase

Parameters:

options - the compiler options for the compilation

Returns:

true if the phase should be performed

getName

public final String getName()

Specified by:

getName in class CompilerPhase

Returns:

a String which is the name of the phase.

printingEnabled

public final 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.

newExecution

public final CompilerPhase newExecution(IR ir)

This phase contains no per-compilation instance fields.

Overrides:

newExecution in class CompilerPhase

Parameters:

ir - the IR that is about to be passed to performPhase

Returns:

an opt compiler phase on which performPhase may be invoked.

perform

public final void perform(IR ir)

Perform peephole branch optimizations.

Specified by:

perform in class CompilerPhase

Parameters:

ir - the IR to optimize

perform

public final void perform(IR ir,
                          boolean renumber)

applySimplify

private static boolean applySimplify(IR ir)

Perform branch simplifications.

Parameters:

ir - the IR to optimize

Returns:

was something reduced

applyPeepholeBranchOpts

protected boolean applyPeepholeBranchOpts(IR ir)

This pass performs peephole branch optimizations. See Muchnick ~p.590

Parameters:

ir - the IR to optimize

optimizeBranchInstruction

protected abstract boolean optimizeBranchInstruction(IR ir,
                                                     Instruction s,
                                                     BasicBlock bb)

This method actually does the work of attempting to peephole optimize a branch instruction.

Parameters:

ir - the containing IR

s - the branch instruction to optimize

bb - the containing basic block

Returns:

true if an optimization was applied, false otherwise

removeUnreachableCode

protected final boolean removeUnreachableCode(IR ir)

Remove unreachable code

Parameters:

ir - the IR to optimize

Returns:

true if did something, false otherwise

maximizeBasicBlocks

protected final void maximizeBasicBlocks(IR ir)

Merge adjacent basic blocks

Parameters:

ir - the IR to optimize

firstLabelFollowing

protected final Instruction firstLabelFollowing(Instruction s)

Given an instruction s, return the first LABEL instruction following s.

firstRealInstructionFollowing

protected final Instruction firstRealInstructionFollowing(Instruction s)

Given an instruction s, return the first real (non-label) instruction following s