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:

ArchitectureSpecificOpt.BURS_STATE, ArchitectureSpecificOpt.BURS_TreeNode

MinimalBURS

MinimalBURS(IR ir)

Create a BURS object for the given IR.

Parameters:

ir - the IR to translate from LIR to MIR.

invoke

public void invoke(BasicBlock bb)

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

Parameters:

bb - The dependence graph. XXX Is this correct?

buildTree

private ArchitectureSpecificOpt.BURS_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

generateTree

private void generateTree(ArchitectureSpecificOpt.BURS_TreeNode k,
                          ArchitectureSpecificOpt.BURS_STATE burs)

Generates code for a single tree root.

Parameters:

k - the root to start generation at

burs -