org.apache.xalan.xsltc.compiler.util
Class MethodGenerator

java.lang.Object
  MethodGen
      org.apache.xalan.xsltc.compiler.util.MethodGenerator

All Implemented Interfaces:

Constants

Direct Known Subclasses:

AttributeSetMethodGenerator, CompareGenerator, MatchGenerator, NamedMethodGenerator, RtMethodGenerator, TestGenerator

public class MethodGenerator
extends MethodGen
implements Constants

Nested Class Summary

private static class	MethodGenerator.Chunk Used to keep track of an outlineable chunk of instructions in the current method.
protected class	MethodGenerator.LocalVariableRegistry Keeps track of all local variables used in the method.

Field Summary

private boolean	_allocatorInit
private Instruction	_aloadDom
private Instruction	_aloadHandler
private Instruction	_aloadIterator
private Instruction	_astoreDom
private Instruction	_astoreHandler
private Instruction	_astoreIterator
private Instruction	_attribute
private Instruction	_endDocument
private Instruction	_endElement
private Instruction	_iloadCurrent
private Instruction	_istoreCurrent
private MethodGenerator.LocalVariableRegistry	_localVariableRegistry
private InstructionList	_mapTypeSub
private Instruction	_namespace
private Instruction	_nextNode
private java.util.Hashtable	_preCompiled A mapping between patterns and instruction lists used by test sequences to avoid compiling the same pattern multiple times.
private Instruction	_reset
private Instruction	_setStartNode
private SlotAllocator	_slotAllocator
private Instruction	_startDocument
private Instruction	_startElement
private Instruction	_uniqueAttribute
private static int	DOM_INDEX
private static java.lang.String	END_ELEMENT_SIG
private static int	HANDLER_INDEX
protected static int	INVALID_INDEX
private static int	ITERATOR_INDEX
private int	m_openChunks Track the number of outlineable chunks started but not yet ended.
private int	m_totalChunks Track the number of outlineable chunks seen.
private static int	MAX_BRANCH_TARGET_OFFSET
private static int	MAX_METHOD_SIZE
private static int	MIN_BRANCH_TARGET_OFFSET
private static int	MINIMUM_OUTLINEABLE_CHUNK_SIZE
private static java.lang.String	START_ELEMENT_SIG
private static int	TARGET_METHOD_SIZE

Fields inherited from interface org.apache.xalan.xsltc.compiler.Constants

ABSOLUTE_ITERATOR, ACC_FINAL, ACC_PRIVATE, ACC_PROTECTED, ACC_PUBLIC, ACC_STATIC, ACC_SUPER, ADD_ATTRIBUTE, ADD_ATTRIBUTE_SIG, ADD_ITERATOR, ADD_ITERATOR_SIG, ADD_PARAMETER, ADD_PARAMETER_SIG, APPLY_TEMPLATES, ATTR_SET_SIG, ATTRIBUTE_LIST_FIELD, ATTRIBUTE_LIST_IMPL_CLASS, ATTRIBUTE_LIST_IMPL_SIG, ATTRIBUTES_SIG, BASIS_LIBRARY_CLASS, BOOLEAN_CLASS, BOOLEAN_VALUE, BOOLEAN_VALUE_SIG, CACHED_NODE_LIST_ITERATOR_CLASS, CHARACTERS, CHARACTERS_SIG, CHARACTERSW, CHARACTERSW_SIG, CLEAR_ATTRIBUTES, CLEAR_ATTRIBUTES_SIG, COLLATOR_CLASS, COLLATOR_SIG, COMPILER_PACKAGE, CURRENT_NODE_LIST_FILTER, CURRENT_NODE_LIST_FILTER_SIG, CURRENT_NODE_LIST_ITERATOR, CURRENT_NODE_LIST_ITERATOR_SIG, DEFAULT_NODE_COUNTER, DEFAULT_NODE_COUNTER_SIG, DOCUMENT_PNAME, DOM_ADAPTER_CLASS, DOM_ADAPTER_SIG, DOM_FIELD, DOM_IMPL, DOM_IMPL_CLASS, DOM_IMPL_SIG, DOM_INTF, DOM_INTF_SIG, DOM_PNAME, DOUBLE_CLASS, DOUBLE_SIG, DOUBLE_VALUE, DOUBLE_VALUE_SIG, DUP_FILTERED_ITERATOR, EMPTYATTR_FIELD, EMPTYSTRING, ERROR, EXPAND_STYLESHEET_QNAME_REF, EXPAND_STYLESHEET_QNAME_SIG, FALLBACK_CLASS, FATAL, FILTER_INTERFACE, FILTER_INTERFACE_SIG, FILTER_ITERATOR, FILTER_STEP_ITERATOR, FORMAT_SYMBOLS_FIELD, GET_ATTRIBUTE_VALUE, GET_ATTRIBUTE_VALUE_SIG, GET_CHILDREN, GET_CHILDREN_SIG, GET_ELEMENT_VALUE, GET_ELEMENT_VALUE_SIG, GET_ITERATOR_SIG, GET_NODE_NAME, GET_NODE_NAME_SIG, GET_NODE_TYPE, GET_NODE_TYPE_SIG, GET_NODE_VALUE, GET_NODE_VALUE_ITERATOR, GET_NODE_VALUE_ITERATOR_SIG, GET_NODE_VALUE_SIG, GET_PARAMETER, GET_PARAMETER_SIG, GET_PARENT, GET_PARENT_SIG, GET_TYPED_CHILDREN, GET_TYPED_CHILDREN_SIG, GET_UNPARSED_ENTITY_URI, GET_UNPARSED_ENTITY_URI_SIG, HAS_ATTRIBUTE, HAS_ATTRIBUTE_SIG, HASIDCALL_INDEX, HASIDCALL_INDEX_SIG, INT_VALUE, INT_VALUE_SIG, INTEGER_CLASS, INTEGER_SIG, INTERNAL, INVOKE_METHOD, ITERATOR_FIELD_SIG, ITERATOR_PNAME, KEY_INDEX_CLASS, KEY_INDEX_ITERATOR_SIG, KEY_INDEX_SIG, LAST_INDEX, LOAD_DOCUMENT_CLASS, LOCALE_CLASS, LOCALE_SIG, LOOKUP_STYLESHEET_QNAME_NS_REF, LOOKUP_STYLESHEET_QNAME_NS_SIG, MAKE_NODE, MAKE_NODE_LIST, MAKE_NODE_LIST_SIG, MAKE_NODE_LIST_SIG2, MAKE_NODE_SIG, MAKE_NODE_SIG2, MATCHING_ITERATOR, MATH_CLASS, MULTI_DOM_CLASS, MULTI_DOM_SIG, NAMES_INDEX, NAMES_INDEX_SIG, NAMESPACE_FEATURE, NAMESPACE_INDEX, NAMESPACE_INDEX_SIG, NEXT, NEXT_SIG, NEXTID, NODE, NODE_COUNTER, NODE_COUNTER_SIG, NODE_FIELD, NODE_FIELD_SIG, NODE_ITERATOR, NODE_ITERATOR_BASE, NODE_ITERATOR_SIG, NODE_PNAME, NODE_SIG, NODE_SORT_FACTORY, NODE_SORT_FACTORY_SIG, NODE_SORT_RECORD, NODE_SORT_RECORD_SIG, NS_ANCESTORS_INDEX_SIG, NTH_ITERATOR_CLASS, OBJECT_CLASS, OBJECT_SIG, ORDER_ITERATOR, ORDER_ITERATOR_SIG, OUTPUT_BASE, OUTPUT_HANDLER, OUTPUT_HANDLER_SIG, POP_PARAM_FRAME, POP_PARAM_FRAME_SIG, POSITION_INDEX, PREFIX_URIS_ARRAY_SIG, PREFIX_URIS_IDX_SIG, PUSH_PARAM_FRAME, PUSH_PARAM_FRAME_SIG, REDIRECT_URI, RESET, RESET_SIG, RTF_INITIAL_SIZE, RUNTIME_NODE_CLASS, RUNTIME_PACKAGE, SAX_IMPL, SAX_IMPL_CLASS, SAX_IMPL_SIG, SET_START_NODE, SET_START_NODE_SIG, SINGLETON_ITERATOR, SORT_ITERATOR, SORT_ITERATOR_SIG, STATIC_CHAR_DATA_FIELD, STATIC_CHAR_DATA_FIELD_SIG, STATIC_NAMES_ARRAY_FIELD, STATIC_NAMESPACE_ARRAY_FIELD, STATIC_NS_ANCESTORS_ARRAY_FIELD, STATIC_PREFIX_URIS_ARRAY_FIELD, STATIC_PREFIX_URIS_IDX_ARRAY_FIELD, STATIC_TYPES_ARRAY_FIELD, STATIC_URIS_ARRAY_FIELD, STEP_ITERATOR_CLASS, STREAM_XML_OUTPUT, STRING, STRING_BUFFER_CLASS, STRING_BUFFER_SIG, STRING_CLASS, STRING_SIG, STRING_TO_INT, STRING_TO_INT_SIG, STRING_TO_REAL, STRING_TO_REAL_SIG, STRING_VALUE_HANDLER, STRING_VALUE_HANDLER_SIG, STRING_WRITER, STRIP_SPACE, STRIP_SPACE_INTF, STRIP_SPACE_PARAMS, STRIP_SPACE_SIG, TRANSLET_CLASS, TRANSLET_FIELD, TRANSLET_FIELD_SIG, TRANSLET_INTF, TRANSLET_INTF_SIG, TRANSLET_OUTPUT_BASE, TRANSLET_OUTPUT_INTERFACE, TRANSLET_OUTPUT_PNAME, TRANSLET_OUTPUT_SIG, TRANSLET_PNAME, TRANSLET_SIG, TRANSLET_URI, TRANSLET_VERSION_INDEX, TRANSLET_VERSION_INDEX_SIG, TYPES_INDEX, TYPES_INDEX_SIG, UNION_ITERATOR_CLASS, UNION_ITERATOR_SIG, UNSUPPORTED, URIS_INDEX, URIS_INDEX_SIG, WARNING, WRITER_SIG, XHTML_URI, XMLNS_PREFIX, XMLNS_STRING, XMLNS_URI, XSLT_PACKAGE, XSLT_URI

Constructor Summary

MethodGenerator(int access_flags, Type return_type, Type[] arg_types, java.lang.String[] arg_names, java.lang.String method_name, java.lang.String class_name, InstructionList il, ConstantPoolGen cpg)

Method Summary

void	addInstructionList(Pattern pattern, InstructionList ilist) Add a pre-compiled pattern to this mode.
LocalVariableGen	addLocalVariable(java.lang.String name, Type type, InstructionHandle start, InstructionHandle end) Allocates a local variable.
LocalVariableGen	addLocalVariable2(java.lang.String name, Type type, InstructionHandle start)
Instruction	attribute()
Instruction	endDocument()
Instruction	endElement()
private java.util.ArrayList	getCandidateChunks(ClassGenerator classGen, int totalMethodSize) Find the outlineable chunks in this method that would be the best choices to outline, based on size and position in the method.
(package private) Method[]	getGeneratedMethods(ClassGenerator classGen) Get all Methods generated by this MethodGenerator.
InstructionList	getInstructionList(Pattern pattern) Get the instruction list for a pre-compiled pattern.
int	getLocalIndex(java.lang.String name)
LocalVariableGen	getLocalVariable(java.lang.String name)
private MethodGenerator.LocalVariableRegistry	getLocalVariableRegistry()
protected Method	getThisMethod()
Instruction	loadContextNode() by default context node is the same as current node.
Instruction	loadCurrentNode()
Instruction	loadDOM()
Instruction	loadHandler()
Instruction	loadIterator()
private static Instruction	loadLocal(int index, Type type) Helper method to generate an instance of a subclass of LoadInstruction based on the specified Type that will load the specified local variable
void	markChunkEnd() Mark the end of an outlineable chunk of code.
void	markChunkStart() Mark the end of the method's InstructionList as the start of an outlineable chunk of code.
private java.util.ArrayList	mergeAdjacentChunks(MethodGenerator.Chunk[] chunks) Merge adjacent sibling chunks to produce larger candidate chunks for outlining
Instruction	namespace()
Instruction	nextNode()
(package private) boolean	offsetInLocalVariableGenRange(LocalVariableGen lvg, int offset) Determines whether a particular variable is in use at a particular offset in the byte code for this method.
private Method	outline(InstructionHandle first, InstructionHandle last, java.lang.String outlinedMethodName, ClassGenerator classGen) Given an outlineable chunk of code in the current MethodGenerator move ("outline") the chunk to a new method, and replace the chunk in the old method with a reference to that new method.
Method[]	outlineChunks(ClassGenerator classGen, int originalMethodSize) Breaks up the IL for this MethodGenerator into separate outlined methods so that no method exceeds the 64KB limit on the length of the byte code associated with a method.
void	removeLocalVariable(LocalVariableGen lvg)
Instruction	reset()
void	setMaxLocals()
Instruction	setStartNode()
Instruction	startDocument()
Instruction	startElement()
Instruction	storeContextNode()
Instruction	storeCurrentNode()
Instruction	storeDOM()
Instruction	storeHandler()
Instruction	storeIterator()
private static Instruction	storeLocal(int index, Type type) Helper method to generate an instance of a subclass of StoreInstruction based on the specified Type that will store a value in the specified local variable
Instruction	uniqueAttribute()
(package private) boolean	widenConditionalBranchTargetOffsets() Rewrites branches to avoid the JVM limits of relative branch offsets.

Methods inherited from class java.lang.Object

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

Field Detail

INVALID_INDEX

protected static final int INVALID_INDEX

See Also:

Constant Field Values

START_ELEMENT_SIG

private static final java.lang.String START_ELEMENT_SIG

See Also:

Constant Field Values

END_ELEMENT_SIG

private static final java.lang.String END_ELEMENT_SIG

See Also:

Constant Field Values

_mapTypeSub

private InstructionList _mapTypeSub

DOM_INDEX

private static final int DOM_INDEX

See Also:

Constant Field Values

ITERATOR_INDEX

private static final int ITERATOR_INDEX

See Also:

Constant Field Values

HANDLER_INDEX

private static final int HANDLER_INDEX

See Also:

Constant Field Values

MAX_METHOD_SIZE

private static final int MAX_METHOD_SIZE

See Also:

Constant Field Values

MAX_BRANCH_TARGET_OFFSET

private static final int MAX_BRANCH_TARGET_OFFSET

See Also:

Constant Field Values

MIN_BRANCH_TARGET_OFFSET

private static final int MIN_BRANCH_TARGET_OFFSET

See Also:

Constant Field Values

TARGET_METHOD_SIZE

private static final int TARGET_METHOD_SIZE

See Also:

Constant Field Values

MINIMUM_OUTLINEABLE_CHUNK_SIZE

private static final int MINIMUM_OUTLINEABLE_CHUNK_SIZE

See Also:

Constant Field Values

_iloadCurrent

private Instruction _iloadCurrent

_istoreCurrent

private Instruction _istoreCurrent

_astoreHandler

private final Instruction _astoreHandler

_aloadHandler

private final Instruction _aloadHandler

_astoreIterator

private final Instruction _astoreIterator

_aloadIterator

private final Instruction _aloadIterator

_aloadDom

private final Instruction _aloadDom

_astoreDom

private final Instruction _astoreDom

_startElement

private final Instruction _startElement

_endElement

private final Instruction _endElement

_startDocument

private final Instruction _startDocument

_endDocument

private final Instruction _endDocument

_attribute

private final Instruction _attribute

_uniqueAttribute

private final Instruction _uniqueAttribute

_namespace

private final Instruction _namespace

_setStartNode

private final Instruction _setStartNode

_reset

private final Instruction _reset

_nextNode

private final Instruction _nextNode

_slotAllocator

private SlotAllocator _slotAllocator

_allocatorInit

private boolean _allocatorInit

_localVariableRegistry

private MethodGenerator.LocalVariableRegistry _localVariableRegistry

_preCompiled

private java.util.Hashtable _preCompiled

A mapping between patterns and instruction lists used by test sequences to avoid compiling the same pattern multiple times. Note that patterns whose kernels are "*", "node()" and "@*" can between shared by test sequences.

m_totalChunks

private int m_totalChunks

Track the number of outlineable chunks seen.

m_openChunks

private int m_openChunks

Track the number of outlineable chunks started but not yet ended. Used to detect imbalances in byte code generation.

Constructor Detail

MethodGenerator

public MethodGenerator(int access_flags,
                       Type return_type,
                       Type[] arg_types,
                       java.lang.String[] arg_names,
                       java.lang.String method_name,
                       java.lang.String class_name,
                       InstructionList il,
                       ConstantPoolGen cpg)

Method Detail

addLocalVariable

public LocalVariableGen addLocalVariable(java.lang.String name,
                                         Type type,
                                         InstructionHandle start,
                                         InstructionHandle end)

Allocates a local variable. If the slot allocator has already been initialized, then call addLocalVariable2() so that the new variable is known to the allocator. Failing to do this may cause the allocator to return a slot that is already in use.

addLocalVariable2

public LocalVariableGen addLocalVariable2(java.lang.String name,
                                          Type type,
                                          InstructionHandle start)

getLocalVariableRegistry

private MethodGenerator.LocalVariableRegistry getLocalVariableRegistry()

offsetInLocalVariableGenRange

boolean offsetInLocalVariableGenRange(LocalVariableGen lvg,
                                      int offset)

Determines whether a particular variable is in use at a particular offset in the byte code for this method.

Preconditions:

• The InstructionList#setPositions() has been called for the InstructionList associated with this MethodGenerator.

Parameters:

lvg - the LocalVariableGen for the variable

offset - the position in the byte code

Returns:

true if and only if the specified variable is in use at the particular byte code offset.

removeLocalVariable

public void removeLocalVariable(LocalVariableGen lvg)

loadDOM

public Instruction loadDOM()

storeDOM

public Instruction storeDOM()

storeHandler

public Instruction storeHandler()

loadHandler

public Instruction loadHandler()

storeIterator

public Instruction storeIterator()

loadIterator

public Instruction loadIterator()

setStartNode

public final Instruction setStartNode()

reset

public final Instruction reset()

nextNode

public final Instruction nextNode()

startElement

public final Instruction startElement()

endElement

public final Instruction endElement()

startDocument

public final Instruction startDocument()

endDocument

public final Instruction endDocument()

attribute

public final Instruction attribute()

uniqueAttribute

public final Instruction uniqueAttribute()

namespace

public final Instruction namespace()

loadCurrentNode

public Instruction loadCurrentNode()

storeCurrentNode

public Instruction storeCurrentNode()

loadContextNode

public Instruction loadContextNode()

by default context node is the same as current node. MK437

storeContextNode

public Instruction storeContextNode()

getLocalIndex

public int getLocalIndex(java.lang.String name)

getLocalVariable

public LocalVariableGen getLocalVariable(java.lang.String name)

setMaxLocals

public void setMaxLocals()

addInstructionList

public void addInstructionList(Pattern pattern,
                               InstructionList ilist)

Add a pre-compiled pattern to this mode.

getInstructionList

public InstructionList getInstructionList(Pattern pattern)

Get the instruction list for a pre-compiled pattern. Used by test sequences to avoid compiling patterns more than once.

getCandidateChunks

private java.util.ArrayList getCandidateChunks(ClassGenerator classGen,
                                               int totalMethodSize)

Find the outlineable chunks in this method that would be the best choices to outline, based on size and position in the method.

Parameters:

classGen - The ClassGen with which the generated methods will be associated

totalMethodSize - the size of the bytecode in the original method

Returns:

a java.util.ArrayList containing the MethodGenerator.Chunks that may be outlined from this method

mergeAdjacentChunks

private java.util.ArrayList mergeAdjacentChunks(MethodGenerator.Chunk[] chunks)

Merge adjacent sibling chunks to produce larger candidate chunks for outlining

Parameters:

chunks - array of sibling MethodGenerator.Chunks that are under consideration for outlining. Chunks must be in the order encountered in the InstructionList

Returns:

a java.util.ArrayList of MethodGenerator.Chunks maximally merged

outlineChunks

public Method[] outlineChunks(ClassGenerator classGen,
                              int originalMethodSize)

Breaks up the IL for this MethodGenerator into separate outlined methods so that no method exceeds the 64KB limit on the length of the byte code associated with a method.

Parameters:

classGen - The ClassGen with which the generated methods will be associated

originalMethodSize - The number of bytes of bytecode represented by the InstructionList of this method

Returns:

an array of the outlined Methods and the original method itself

outline

private Method outline(InstructionHandle first,
                       InstructionHandle last,
                       java.lang.String outlinedMethodName,
                       ClassGenerator classGen)

Given an outlineable chunk of code in the current MethodGenerator move ("outline") the chunk to a new method, and replace the chunk in the old method with a reference to that new method. No OutlineableChunkStart or OutlineableChunkEnd instructions are copied.

Parameters:

first - The InstructionHandle of the first instruction in the chunk to outline

last - The InstructionHandle of the last instruction in the chunk to outline

outlinedMethodName - The name of the new method

classGen - The ClassGenerator of which the original and new methods will be members

Returns:

The new Method containing the outlined code.

loadLocal

private static Instruction loadLocal(int index,
                                     Type type)

Helper method to generate an instance of a subclass of LoadInstruction based on the specified Type that will load the specified local variable

Parameters:

index - the JVM stack frame index of the variable that is to be loaded

type - the Type of the variable

Returns:

the generated LoadInstruction

storeLocal

private static Instruction storeLocal(int index,
                                      Type type)

Helper method to generate an instance of a subclass of StoreInstruction based on the specified Type that will store a value in the specified local variable

Parameters:

index - the JVM stack frame index of the variable that is to be stored

type - the Type of the variable

Returns:

the generated StoredInstruction

markChunkStart

public void markChunkStart()

Mark the end of the method's InstructionList as the start of an outlineable chunk of code. The outlineable chunk begins after the InstructionHandle that is at the end of the method's InstructionList, or at the start of the method if the InstructionList is empty. See OutlineableChunkStart for more information.

markChunkEnd

public void markChunkEnd()

Mark the end of an outlineable chunk of code. See OutlineableChunkStart for more information.

getGeneratedMethods

Method[] getGeneratedMethods(ClassGenerator classGen)

Get all Methods generated by this MethodGenerator. The MethodGen#getMethod() only returns a single Method object. This method takes into account the Java Virtual Machine Specification limit of 64KB on the size of a method, and may return more than one Method.

If the code associated with the MethodGenerator would exceed the 64KB limit, this method will attempt to split the code in the InstructionList associated with this MethodGenerator into several methods.

Parameters:

classGen - the ClassGenerator of which these methods are members

Returns:

an array of all the Methods generated

getThisMethod

protected Method getThisMethod()

widenConditionalBranchTargetOffsets

boolean widenConditionalBranchTargetOffsets()

Rewrites branches to avoid the JVM limits of relative branch offsets. There is no need to invoke this method if the bytecode for the MethodGenerator does not exceed 32KB.

The Java Virtual Machine Specification permits the code portion of a method to be up to 64KB in length. However, some control transfer instructions specify relative offsets as a signed 16-bit quantity, limiting the range to a subset of the instructions that might be in a method.

The TABLESWITCH and LOOKUPSWITCH instructions always use 32-bit signed relative offsets, so they are immune to this problem.

The GOTO and JSR instructions come in two forms, one of which uses 16-bit relative offsets, and the other of which uses 32-bit relative offsets. The BCEL library decides whether to use the wide form of GOTO or JSRinstructions based on the relative offset of the target of the instruction without any intervention by the user of the library.

This leaves the various conditional branch instructions, IFEQ, IFNULL, IF_ICMPEQ, et al., all of which use 16-bit signed relative offsets, with no 32-bit wide form available.

This method scans the InstructionList associated with this MethodGenerator and finds all conditional branch instructions that might exceed the 16-bit limitation for relative branch offsets. The logic of each such instruction is inverted, and made to target the instruction which follows it. An unconditional branch to the original target of the instruction is then inserted between the conditional branch and the instruction which previously followed it. The unconditional branch is permitted to have a 16-bit or a 32-bit relative offset, as described above. For example, 1234: NOP ... 55278: IFEQ -54044 55280: NOP is rewritten as 1234: NOP ... 55278: IFNE 7 55280: GOTO_W -54046 55285: NOP

Preconditions:

• The InstructionList#setPositions() has been called for the InstructionList associated with this MethodGenerator.

Postconditions:

• Any further changes to the InstructionList for this MethodGenerator will invalidate the changes made by this method.

Returns:

true if the InstructionList was modified; false otherwise

See Also:

Java Virtual Machine Specification, Second Edition