org.jikesrvm.compilers.opt.lir2mir

Class MinimalBURS

java.lang.Object

org.jikesrvm.compilers.opt.lir2mir.BURS

org.jikesrvm.compilers.opt.lir2mir.MinimalBURS

final class MinimalBURS
extends BURS

This class contains code for quick and dirty instruction selection by forcing each instruction to be a tree and generating the trees in the same input as the input LIR instructions. This results in poor code quality, but can be done very quickly. The intended purpose is to reduce compile time by doing quick and dirty instruction selection for infrequently executed basic blocks.

See Also:

BURS_StateCoder, AbstractBURS_TreeNode

Field Summary

Fields inherited from class org.jikesrvm.compilers.opt.lir2mir.BURS

AddressConstant, BranchTarget, DEBUG, ir, lastInstr, LongConstant, NullTreeNode, Register

Constructor Summary

Constructors

Constructor and Description
MinimalBURS(IR ir) Create a BURS object for the given IR.

Method Summary

Modifier and Type	Method and Description
private AbstractBURS_TreeNode	buildTree(Instruction s) Build a BURS Tree for each Instruction.
private void	generateTree(AbstractBURS_TreeNode k, BURS_StateCoder burs) Generates code for a single tree root.
void	invoke(BasicBlock bb) Build BURS trees for the basic block bb, label the trees, and then generate MIR instructions based on the labeling.

Methods inherited from class org.jikesrvm.compilers.opt.lir2mir.BURS

action, append, debug, dumpTree, finalizeBlock, label, makeCoder, mark, prepareForBlock

Methods inherited from class java.lang.Object

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

Constructor Detail

MinimalBURS

MinimalBURS(IR ir)

Create a BURS object for the given IR.

Parameters:

ir - the IR to translate from LIR to MIR.

Method Detail

invoke

public void invoke(BasicBlock bb)

Build BURS trees for the basic block bb, label the trees, and then generate MIR instructions based on the labeling.

Parameters:

bb - the basic block to process

buildTree

private AbstractBURS_TreeNode buildTree(Instruction s)

Build a BURS Tree for each Instruction. Complete BURS trees by adding leaf nodes as needed, and creating tree edges by calling insertChild1() or insertChild2() This step is also where we introduce intermediate tree nodes for any LIR instruction that has > 2 "real" operands e.g., a CALL.

Parameters:

s - The instruction for which a tree must be built

Returns:

the root of the newly constructed tree

generateTree

private void generateTree(AbstractBURS_TreeNode k,
                          BURS_StateCoder burs)

Generates code for a single tree root.

Parameters:

k - the root to start generation at

burs - the current BURS state