org.checkerframework.dataflow.cfg

Class CFGBuilder

java.lang.Object

org.checkerframework.dataflow.cfg.CFGBuilder

Direct Known Subclasses:

CFCFGBuilder

public class CFGBuilder
extends Object

Builds the control flow graph of some Java code (either a method, or an arbitrary statement).

The translation of the AST to the CFG is split into three phases:

1. Phase one. In the first phase, the AST is translated into a sequence of CFGBuilder.ExtendedNodes. An extended node can either be a Node, or one of several meta elements such as a conditional or unconditional jump or a node with additional information about exceptions. Some of the extended nodes contain labels (e.g., for the jump target), and phase one additionally creates a mapping from labels to extended nodes. Finally, the list of leaders is computed: A leader is an extended node which will give rise to a basic block in phase two.
2. Phase two. In this phase, the sequence of extended nodes is translated to a graph of control flow blocks that contain nodes. The meta elements from phase one are translated into the correct edges.
3. Phase three. The control flow graph generated in phase two can contain degenerate basic blocks such as empty regular basic blocks or conditional basic blocks that have the same block as both 'then' and 'else' successor. This phase removes these cases while preserving the control flow structure.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static class	CFGBuilder.CFGTranslationPhaseOne Class that performs phase one of the translation process.
protected static class	CFGBuilder.CFGTranslationPhaseThree Class that performs phase three of the translation process.
protected static class	CFGBuilder.CFGTranslationPhaseTwo Class that performs phase two of the translation process.
protected static class	CFGBuilder.ConditionalJump An extended node of type CFGBuilder.ExtendedNode.ExtendedNodeType.CONDITIONAL_JUMP.
protected static class	CFGBuilder.ExtendedNode An extended node can be one of several things (depending on its type): NODE.
protected static class	CFGBuilder.Label A label is used to refer to other extended nodes using a mapping from labels to extended nodes.
protected static class	CFGBuilder.NodeHolder An extended node of type NODE.
protected static class	CFGBuilder.NodeWithExceptionsHolder An extended node of type EXCEPTION_NODE.
protected static class	CFGBuilder.PhaseOneResult A wrapper object to pass around the result of phase one.
protected static class	CFGBuilder.TryCatchFrame A TryCatchFrame contains an ordered list of catch labels that apply to exceptions with specific types.
protected static class	CFGBuilder.TryFinallyFrame A TryFinallyFrame applies to exceptions of any type.
protected static class	CFGBuilder.TryFinallyScopeCell Storage cell for a single Label, with tracking whether it was accessed.
protected static class	CFGBuilder.TryFinallyScopeMap A map that keeps track of new labels added within a try block.
protected static interface	CFGBuilder.TryFrame A TryFrame takes a thrown exception type and maps it to a set of possible control-flow successors.
protected static class	CFGBuilder.TryStack An exception stack represents the set of all try-catch blocks in effect at a given point in a program.
protected static class	CFGBuilder.Tuple<A,B,C> Tuple class with up to three members.
protected static class	CFGBuilder.UnconditionalJump An extended node of type CFGBuilder.ExtendedNode.ExtendedNodeType.UNCONDITIONAL_JUMP.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	CFGBuilder() This class should never be instantiated.

Method Summary

Modifier and Type	Method and Description
static ControlFlowGraph	build(CompilationUnitTree root, MethodTree tree, @Nullable ClassTree classTree, @Nullable ProcessingEnvironment env) Build the control flow graph of a method.
static ControlFlowGraph	build(CompilationUnitTree root, UnderlyingAST underlyingAST, boolean assumeAssertionsEnabled, boolean assumeAssertionsDisabled, ProcessingEnvironment env) Build the control flow graph of some code.
static ControlFlowGraph	build(CompilationUnitTree root, UnderlyingAST underlyingAST, ProcessingEnvironment env) Build the control flow graph of some code.
static ControlFlowGraph	build(TreePath bodyPath, UnderlyingAST underlyingAST, boolean assumeAssertionsEnabled, boolean assumeAssertionsDisabled, ProcessingEnvironment env) Build the control flow graph of some code (method, initializer block, ...).
protected static void	printBlocks(Set<Block> blocks) Print a set of Blocks and the edges between them.

Methods inherited from class java.lang.Object

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

Constructor Detail

CFGBuilder

protected CFGBuilder()

This class should never be instantiated. Protected to still allow subclasses.

Method Detail

build

public static ControlFlowGraph build(CompilationUnitTree root,
                                     UnderlyingAST underlyingAST,
                                     boolean assumeAssertionsEnabled,
                                     boolean assumeAssertionsDisabled,
                                     ProcessingEnvironment env)

Build the control flow graph of some code.

build

public static ControlFlowGraph build(TreePath bodyPath,
                                     UnderlyingAST underlyingAST,
                                     boolean assumeAssertionsEnabled,
                                     boolean assumeAssertionsDisabled,
                                     ProcessingEnvironment env)

Build the control flow graph of some code (method, initializer block, ...). bodyPath is the TreePath to the body of that code.

build

public static ControlFlowGraph build(CompilationUnitTree root,
                                     UnderlyingAST underlyingAST,
                                     ProcessingEnvironment env)

Build the control flow graph of some code.

build

public static ControlFlowGraph build(CompilationUnitTree root,
                                     MethodTree tree,
                                     @Nullable ClassTree classTree,
                                     @Nullable ProcessingEnvironment env)

Build the control flow graph of a method.

printBlocks

protected static void printBlocks(Set<Block> blocks)

Print a set of Blocks and the edges between them. This is useful for examining the results of phase two.