Optimizer.pod

NAME

Tree::Optimizer - A tool for scheduling optimization passes

DESCRIPTION

Tree::Optimizer and its subclasses allow specifying a set of transformations (called passes) to be performed on a tree and the dependencies between those passes. Once the passes and their dependencies have been registered, the run method will run the registered passes on a tree, ensuring that each pass runs after any passes on which it depends.

Tree::Optimizer

Public methods

new()

Create a new Tree::Optimizer.

find-pass(name)

Returns the pass that was registered with the specified name or an Undef PMC if no pass has been registered with the specified name.

register(transformation, adverbs :named :slurpy)

Registers a pass to be run. The transformation may be either a Tree::Optimizer::Pass object, in which case, it is cloned and registered. Otherwise, it is assumed to be an invokable object that performs the desired transformation, and it is used to create a new object of the class returned by the pass-class method. It is an error to supply a null transformation.

The adverbs slurpy named parameter accepts all of the named parameters that Tree::Optimizer::Pass.new does. They are generally simply passed on to Tree::Optimizer::Pass.new. The name and depends-on named parameters are two exceptions. If the transformation is a pass object, then the name of the pass is changed to the supplied name, if any, and the dependencies in the supplied depends-on parameter are added to those listed in the pass obejct itself.

add-dependency(dependent, dependency)

Marks the pass named dependent as depending on the pass named dependency.

remove-dependency(dependent, dependency)

Removes dependent's dependency on dependency. This does not modify the list of the dependencies of the dependent pass. It causes the optimizer to forget that dependent depends on dependency. If dependent does not depend on dependency, the remove-dependency method throws an exception.

run(tree, combine :named)

Runs the registered passes on the tree. If the combine option is supplied and is true, any adjacent passes with a when pattern and with the recursive flag set will be performed in a single traversal of the tree.

Overridden methods

These methods are intended to be overridden in subclasses in order to augment Tree::Optimizer's behavior.

pass-class()

Returns the Tree::Optimizer::Pass subclass which should be used to create new passes.

combine-passes(passes :slurpy)

Creates a single Tree::Optimizer::CombinedPass from the supplied passes.

Internal methods

These methods are used internally and should not generally be used by users of Tree::Optimizer.

BUILD()

Initializes a newly-created Tree::Optimizer. It is called by new.

run-pass(name, tree)

Runs the pass with the supplied name on the tree.

pass-order(combine :named)

Produce the list of passes that the optimizer should run in the correct order. If combine is provided and true, combine adjacent when/recursive passes into single CombinedPasses.