asm 9.6 · org.objectweb.asm.Frame

The input and output stack map frames of a basic block.

Stack map frames are computed in two steps:

During the visit of each instruction in MethodWriter, the state of the frame at the end of the current basic block is updated by simulating the action of the instruction on the previous state of this so called "output frame".
After all instructions have been visited, a fix point algorithm is used in MethodWriter to compute the "input frame" of each basic block (i.e. the stack map frame at the beginning of the basic block). See MethodWriter#computeAllFrames.

Output stack map frames are computed relatively to the input frame of the basic block, which is not yet known when output frames are computed. It is therefore necessary to be able to represent abstract types such as "the type at position x in the input frame locals" or "the type at position x from the top of the input frame stack" or even "the type at position x in the input frame, with y more (or less) array dimensions". This explains the rather complicated type format used in this class, explained below.

The local variables and the operand stack of input and output frames contain values called "abstract types" hereafter. An abstract type is represented with 4 fields named DIM, KIND, FLAGS and VALUE, packed in a single int value for better performance and memory efficiency:

  =====================================
  |...DIM|KIND|.F|...............VALUE|
  =====================================

the DIM field, stored in the 6 most significant bits, is a signed number of array dimensions (from -32 to 31, included). It can be retrieved with DIM_MASK and a right shift of DIM_SHIFT.
the KIND field, stored in 4 bits, indicates the kind of VALUE used. These 4 bits can be retrieved with KIND_MASK and, without any shift, must be equal to CONSTANT_KIND, REFERENCE_KIND, UNINITIALIZED_KIND, FORWARD_UNINITIALIZED_KIND,LOCAL_KIND or STACK_KIND.
the FLAGS field, stored in 2 bits, contains up to 2 boolean flags. Currently only one flag is defined, namely TOP_IF_LONG_OR_DOUBLE_FLAG.
the VALUE field, stored in the remaining 20 bits, contains either
- one of the constants ITEM_TOP, ITEM_ASM_BOOLEAN, ITEM_ASM_BYTE, ITEM_ASM_CHAR or ITEM_ASM_SHORT, ITEM_INTEGER, ITEM_FLOAT, ITEM_LONG, ITEM_DOUBLE, ITEM_NULL or ITEM_UNINITIALIZED_THIS, if KIND is equal to CONSTANT_KIND.
- the index of a Symbol#TYPE_TAG Symbol in the type table of a SymbolTable, if KIND is equal to REFERENCE_KIND.
- the index of an Symbol#UNINITIALIZED_TYPE_TAG Symbol in the type table of a SymbolTable, if KIND is equal to UNINITIALIZED_KIND.
- the index of a Symbol#FORWARD_UNINITIALIZED_TYPE_TAG Symbol in the type table of a SymbolTable, if KIND is equal to FORWARD_UNINITIALIZED_KIND.
- the index of a local variable in the input stack frame, if KIND is equal to LOCAL_KIND.
- a position relatively to the top of the stack of the input stack frame, if KIND is equal to STACK_KIND,

Output frames can contain abstract types of any kind and with a positive or negative array dimension (and even unassigned types, represented by 0 - which does not correspond to any valid abstract type value). Input frames can only contain CONSTANT_KIND, REFERENCE_KIND, UNINITIALIZED_KIND or FORWARD_UNINITIALIZED_KIND abstract types of positive or null array dimension. In all cases the type table contains only internal type names (array type descriptors are forbidden - array dimensions must be represented through the DIM field).

The LONG and DOUBLE types are always represented by using two slots (LONG + TOP or DOUBLE + TOP), for local variables as well as in the operand stack. This is necessary to be able to simulate DUPx_y instructions, whose effect would be dependent on the concrete types represented by the abstract types in the stack (which are not always known).

Field Summary

Modifier and Type	Field and Description
pack-priv static final int	APPEND_FRAME
private static final int	ARRAY_OF The constant to be added to an abstract type to get one with one more array dimension.
private static final int	BOOLEAN
private static final int	BYTE
private static final int	CHAR
pack-priv static final int	CHOP_FRAME
private static final int	CONSTANT_KIND
private static final int	DIM_MASK
private static final int	DIM_SHIFT
private static final int	DIM_SIZE
private static final int	DOUBLE
private static final int	ELEMENT_OF The constant to be added to an abstract type to get one with one less array dimension.
private static final int	FLAGS_SHIFT
private static final int	FLAGS_SIZE
private static final int	FLOAT
private static final int	FORWARD_UNINITIALIZED_KIND
pack-priv static final int	FULL_FRAME
private int	initializationCount The number of types that are initialized in the basic block.
private int[]	initializations The abstract types that are initialized in the basic block.
private int[]	inputLocals The input stack map frame locals.
private int[]	inputStack The input stack map frame stack.
private static final int	INTEGER
private static final int	ITEM_ASM_BOOLEAN
private static final int	ITEM_ASM_BYTE
private static final int	ITEM_ASM_CHAR
private static final int	ITEM_ASM_SHORT
pack-priv static final int	ITEM_DOUBLE
pack-priv static final int	ITEM_FLOAT
pack-priv static final int	ITEM_INTEGER
pack-priv static final int	ITEM_LONG
pack-priv static final int	ITEM_NULL
pack-priv static final int	ITEM_OBJECT
pack-priv static final int	ITEM_TOP
pack-priv static final int	ITEM_UNINITIALIZED
pack-priv static final int	ITEM_UNINITIALIZED_THIS
private static final int	KIND_MASK
private static final int	KIND_SHIFT
private static final int	KIND_SIZE
private static final int	LOCAL_KIND
private static final int	LONG
private static final int	NULL
private int[]	outputLocals The output stack map frame locals.
private int[]	outputStack The output stack map frame stack.
private short	outputStackStart The start of the output stack, relatively to the input stack.
private short	outputStackTop The index of the top stack element in `outputStack`.
pack-priv Label	owner The basic block to which these input and output stack map frames correspond.
private static final int	REFERENCE_KIND
pack-priv static final int	RESERVED
pack-priv static final int	SAME_FRAME
pack-priv static final int	SAME_FRAME_EXTENDED
pack-priv static final int	SAME_LOCALS_1_STACK_ITEM_FRAME
pack-priv static final int	SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED
private static final int	SHORT
private static final int	STACK_KIND
private static final int	TOP
private static final int	TOP_IF_LONG_OR_DOUBLE_FLAG A flag used for LOCAL_KIND and STACK_KIND abstract types, indicating that if the resolved, concrete type is LONG or DOUBLE, TOP should be used instead (because the value has been partially overridden with an xSTORE instruction).
private static final int	UNINITIALIZED_KIND
private static final int	UNINITIALIZED_THIS
private static final int	VALUE_MASK
private static final int	VALUE_SIZE

Constructor Summary

Access	Constructor and Description
pack-priv	Frame(final Label the basic block to which these input and output stack map frames correspond. owner) Constructs a new Frame.

Method Summary

Modifier and Type	Method and Description
pack-priv final void	accept(final MethodWriter the `MethodWriter` that should visit the input frame of this `Frame`. methodWriter) Makes the given `MethodWriter` visit the input frame of this `Frame`.
private void	addInitializedType(final int an abstract type on a which a constructor is invoked. abstractType) Adds an abstract type to the list of types on which a constructor is invoked in the basic block.
pack-priv final void	copyFrom(final Frame The new frame value. frame) Sets this frame to the value of the given frame.
pack-priv void	execute(final int the opcode of the instruction. opcode, final int the numeric operand of the instruction, if any. arg, final Symbol the Symbol operand of the instruction, if any. argSymbol, final SymbolTable the type table to use to lookup and store type `Symbol`. symbolTable) Simulates the action of the given instruction on the output stack frame.
pack-priv static int	Returns: the abstract type corresponding to the given frame element type. getAbstractTypeFromApiFormat(final SymbolTable the type table to use to lookup and store type `Symbol`. symbolTable, final Object a frame element type described using the same format as in `MethodVisitor#visitFrame`, i.e. either `Opcodes#TOP`, `Opcodes#INTEGER`, `Opcodes#FLOAT`, `Opcodes#LONG`, `Opcodes#DOUBLE`, `Opcodes#NULL`, or `Opcodes#UNINITIALIZED_THIS`, or the internal name of a class, or a Label designating a NEW instruction (for uninitialized types). type) Returns the abstract type corresponding to the given public API frame element type.
private static int	Returns: the abstract type corresponding to the given type descriptor. getAbstractTypeFromDescriptor(final SymbolTable the type table to use to lookup and store type `Symbol`. symbolTable, final String a string ending with a type descriptor. buffer, final int the start offset of the type descriptor in buffer. offset) Returns the abstract type corresponding to the given type descriptor.
pack-priv static int	Returns: the abstract type value corresponding to the given internal name. getAbstractTypeFromInternalName(final SymbolTable the type table to use to lookup and store type `Symbol`. symbolTable, final String the internal name of a class. This must not be an array type descriptor. internalName) Returns the abstract type corresponding to the internal name of a class.
private int	Returns: the concrete output type corresponding to 'abstractOutputType'. getConcreteOutputType(final int an abstract output type. abstractOutputType, final int the size of the input stack, used to resolve abstract output types of STACK_KIND kind. numStack) Computes the concrete output type corresponding to a given abstract output type.
private int	Returns: the REFERENCE_KIND abstract type corresponding to abstractType if it is UNINITIALIZED_THIS or an UNINITIALIZED_KIND or FORWARD_UNINITIALIZED_KIND abstract type for one of the types on which a constructor is invoked in the basic block. Otherwise returns abstractType. getInitializedType(final SymbolTable the type table to use to lookup and store type `Symbol`. symbolTable, final int an abstract type. abstractType) Returns the "initialized" abstract type corresponding to the given abstract type.
pack-priv final int	getInputStackSize()
private int	Returns: the abstract type stored at the given local variable index in the output frame. getLocal(final int the index of the local variable whose value must be returned. localIndex) Returns the abstract type stored at the given local variable index in the output frame.
pack-priv final boolean	Returns: true if the input frame of 'frame' has been changed by this operation. merge(final SymbolTable the type table to use to lookup and store type `Symbol`. symbolTable, final Frame the `Frame` whose input frame must be updated. This should be the frame of a successor, in the control flow graph, of the basic block corresponding to this frame. dstFrame, final int if 'frame' corresponds to an exception handler basic block, the type table index of the caught exception type, otherwise 0. catchTypeIndex) Merges the input frame of the given `Frame` with the input and output frames of this `Frame`.
private static boolean	Returns: true if the type array has been modified by this operation. merge(final SymbolTable the type table to use to lookup and store type `Symbol`. symbolTable, final int the abstract type with which the abstract type array element must be merged. This type should be of `CONSTANT_KIND`, `REFERENCE_KIND`, `UNINITIALIZED_KIND` or `FORWARD_UNINITIALIZED_KIND` kind, with positive or null array dimensions. sourceType, final int[] an array of abstract types. These types should be of `CONSTANT_KIND`, `REFERENCE_KIND`, `UNINITIALIZED_KIND` or `FORWARD_UNINITIALIZED_KIND` kind, with positive or null array dimensions. dstTypes, final int the index of the type that must be merged in dstTypes. dstIndex) Merges the type at the given index in the given abstract type array with the given type.
private int	Returns: the abstract type that has been popped from the output frame stack. pop() Pops an abstract type from the output frame stack and returns its value.
private void	pop(final int the number of abstract types that must be popped. elements) Pops the given number of abstract types from the output frame stack.
private void	pop(final String a type or method descriptor (in which case its argument types are popped). descriptor) Pops as many abstract types from the output frame stack as described by the given descriptor.
private void	push(final int an abstract type. abstractType) Pushes the given abstract type on the output frame stack.
private void	push(final SymbolTable the type table to use to lookup and store type `Symbol`. symbolTable, final String a type or method descriptor (in which case its return type is pushed). descriptor) Pushes the abstract type corresponding to the given descriptor on the output frame stack.
pack-priv static void	putAbstractType(final SymbolTable the type table to use to lookup and store type `Symbol`. symbolTable, final int an abstract type, restricted to `Frame#CONSTANT_KIND`, `Frame#REFERENCE_KIND`, `Frame#UNINITIALIZED_KIND` or `Frame#FORWARD_UNINITIALIZED_KIND` types. abstractType, final ByteVector where the abstract type must be put. output) Put the given abstract type in the given ByteVector, using the JVMS verification_type_info format used in StackMapTable attributes.
pack-priv final void	setInputFrameFromApiFormat(final SymbolTable the type table to use to lookup and store type `Symbol`. symbolTable, final int the number of local variables. numLocal, final Object[] the local variable types, described using the same format as in `MethodVisitor#visitFrame`. local, final int the number of operand stack elements. numStack, final Object[] the operand stack types, described using the same format as in `MethodVisitor#visitFrame`. stack) Sets the input frame from the given public API frame description.
pack-priv final void	setInputFrameFromDescriptor(final SymbolTable the type table to use to lookup and store type `Symbol`. symbolTable, final int the method's access flags. access, final String the method descriptor. descriptor, final int the maximum number of local variables of the method. maxLocals) Sets the input frame from the given method description.
private void	setLocal(final int the index of the output frame local variable that must be set. localIndex, final int the value that must be set. abstractType) Replaces the abstract type stored at the given local variable index in the output frame.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

APPEND_FRAME	back to summary
pack-priv static final int APPEND_FRAME

ARRAY_OF	back to summary
private static final int ARRAY_OF The constant to be added to an abstract type to get one with one more array dimension.

BOOLEAN	back to summary
private static final int BOOLEAN

BYTE	back to summary
private static final int BYTE

CHAR	back to summary
private static final int CHAR

CHOP_FRAME	back to summary
pack-priv static final int CHOP_FRAME

CONSTANT_KIND	back to summary
private static final int CONSTANT_KIND

DIM_MASK	back to summary
private static final int DIM_MASK

DIM_SHIFT	back to summary
private static final int DIM_SHIFT

DIM_SIZE	back to summary
private static final int DIM_SIZE

DOUBLE	back to summary
private static final int DOUBLE

ELEMENT_OF	back to summary
private static final int ELEMENT_OF The constant to be added to an abstract type to get one with one less array dimension.

FLAGS_SHIFT	back to summary
private static final int FLAGS_SHIFT

FLAGS_SIZE	back to summary
private static final int FLAGS_SIZE

FLOAT	back to summary
private static final int FLOAT

FORWARD_UNINITIALIZED_KIND	back to summary
private static final int FORWARD_UNINITIALIZED_KIND

FULL_FRAME	back to summary
pack-priv static final int FULL_FRAME

initializationCount	back to summary
private int initializationCount The number of types that are initialized in the basic block. See `initializations`.

initializations	back to summary
private int[] initializations The abstract types that are initialized in the basic block. A constructor invocation on an UNINITIALIZED, FORWARD_UNINITIALIZED or UNINITIALIZED_THIS abstract type must replace every occurrence of this type in the local variables and in the operand stack. This cannot be done during the first step of the algorithm since, during this step, the local variables and the operand stack types are still abstract. It is therefore necessary to store the abstract types of the constructors which are invoked in the basic block, in order to do this replacement during the second step of the algorithm, where the frames are fully computed. Note that this array can contain abstract types that are relative to the input locals or to the input stack.

initializations

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private int[] initializations

The abstract types that are initialized in the basic block. A constructor invocation on an UNINITIALIZED, FORWARD_UNINITIALIZED or UNINITIALIZED_THIS abstract type must replace every occurrence of this type in the local variables and in the operand stack. This cannot be done during the first step of the algorithm since, during this step, the local variables and the operand stack types are still abstract. It is therefore necessary to store the abstract types of the constructors which are invoked in the basic block, in order to do this replacement during the second step of the algorithm, where the frames are fully computed. Note that this array can contain abstract types that are relative to the input locals or to the input stack.

inputLocals	back to summary
private int[] inputLocals The input stack map frame locals. This is an array of abstract types.

inputStack	back to summary
private int[] inputStack The input stack map frame stack. This is an array of abstract types.

INTEGER	back to summary
private static final int INTEGER

ITEM_ASM_BOOLEAN	back to summary
private static final int ITEM_ASM_BOOLEAN

ITEM_ASM_BYTE	back to summary
private static final int ITEM_ASM_BYTE

ITEM_ASM_CHAR	back to summary
private static final int ITEM_ASM_CHAR

ITEM_ASM_SHORT	back to summary
private static final int ITEM_ASM_SHORT

ITEM_DOUBLE	back to summary
pack-priv static final int ITEM_DOUBLE

ITEM_FLOAT	back to summary
pack-priv static final int ITEM_FLOAT

ITEM_INTEGER	back to summary
pack-priv static final int ITEM_INTEGER

ITEM_LONG	back to summary
pack-priv static final int ITEM_LONG

ITEM_NULL	back to summary
pack-priv static final int ITEM_NULL

ITEM_OBJECT	back to summary
pack-priv static final int ITEM_OBJECT

ITEM_TOP	back to summary
pack-priv static final int ITEM_TOP

ITEM_UNINITIALIZED	back to summary
pack-priv static final int ITEM_UNINITIALIZED

ITEM_UNINITIALIZED_THIS	back to summary
pack-priv static final int ITEM_UNINITIALIZED_THIS

KIND_MASK	back to summary
private static final int KIND_MASK

KIND_SHIFT	back to summary
private static final int KIND_SHIFT

KIND_SIZE	back to summary
private static final int KIND_SIZE

LOCAL_KIND	back to summary
private static final int LOCAL_KIND

LONG	back to summary
private static final int LONG

NULL	back to summary
private static final int NULL

outputLocals	back to summary
private int[] outputLocals The output stack map frame locals. This is an array of abstract types.

outputStack	back to summary
private int[] outputStack The output stack map frame stack. This is an array of abstract types.

outputStackStart	back to summary
private short outputStackStart The start of the output stack, relatively to the input stack. This offset is always negative or null. A null offset means that the output stack must be appended to the input stack. A -n offset means that the first n output stack elements must replace the top n input stack elements, and that the other elements must be appended to the input stack.

outputStackTop	back to summary
private short outputStackTop The index of the top stack element in `outputStack`.

owner	back to summary
pack-priv Label owner The basic block to which these input and output stack map frames correspond.

REFERENCE_KIND	back to summary
private static final int REFERENCE_KIND

RESERVED	back to summary
pack-priv static final int RESERVED

SAME_FRAME	back to summary
pack-priv static final int SAME_FRAME

SAME_FRAME_EXTENDED	back to summary
pack-priv static final int SAME_FRAME_EXTENDED

SAME_LOCALS_1_STACK_ITEM_FRAME	back to summary
pack-priv static final int SAME_LOCALS_1_STACK_ITEM_FRAME

SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED	back to summary
pack-priv static final int SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED

SHORT	back to summary
private static final int SHORT

STACK_KIND	back to summary
private static final int STACK_KIND

TOP	back to summary
private static final int TOP

TOP_IF_LONG_OR_DOUBLE_FLAG	back to summary
private static final int TOP_IF_LONG_OR_DOUBLE_FLAG A flag used for LOCAL_KIND and STACK_KIND abstract types, indicating that if the resolved, concrete type is LONG or DOUBLE, TOP should be used instead (because the value has been partially overridden with an xSTORE instruction).

UNINITIALIZED_KIND	back to summary
private static final int UNINITIALIZED_KIND

UNINITIALIZED_THIS	back to summary
private static final int UNINITIALIZED_THIS

VALUE_MASK	back to summary
private static final int VALUE_MASK

VALUE_SIZE	back to summary
private static final int VALUE_SIZE

Constructor Detail

Frame

back to summary

pack-priv Frame(final Label owner)

Constructs a new Frame.

Parameters

owner:Label: the basic block to which these input and output stack map frames correspond.

Method Detail

accept back to summary

pack-priv final void accept(final MethodWriter methodWriter)

Makes the given MethodWriter visit the input frame of this Frame. The visit is done with the MethodWriter#visitFrameStart, MethodWriter#visitAbstractType and MethodWriter#visitFrameEnd methods.

Parameters

methodWriter:MethodWriter: the MethodWriter that should visit the input frame of this Frame.

addInitializedType

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private void addInitializedType(final int abstractType)

Adds an abstract type to the list of types on which a constructor is invoked in the basic block.

Parameters

abstractType:int: an abstract type on a which a constructor is invoked.

copyFrom

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pack-priv final void copyFrom(final Frame frame)

Sets this frame to the value of the given frame.

Warning

after this method is called the two frames share the same data structures. It is recommended to discard the given frame to avoid unexpected side effects.

Parameters

frame:Frame: The new frame value.

execute back to summary

pack-priv void execute(final int opcode, final int arg, final Symbol argSymbol, final SymbolTable symbolTable)

Simulates the action of the given instruction on the output stack frame.

Parameters

opcode:int: the opcode of the instruction.
arg:int: the numeric operand of the instruction, if any.
argSymbol:Symbol: the Symbol operand of the instruction, if any.
symbolTable:SymbolTable: the type table to use to lookup and store type Symbol.

getAbstractTypeFromApiFormat back to summary

pack-priv static int getAbstractTypeFromApiFormat(final SymbolTable symbolTable, final Object type)

Returns the abstract type corresponding to the given public API frame element type.

Parameters

symbolTable:SymbolTable: the type table to use to lookup and store type Symbol.
type:Object: a frame element type described using the same format as in MethodVisitor#visitFrame, i.e. either Opcodes#TOP, Opcodes#INTEGER, Opcodes#FLOAT, Opcodes#LONG, Opcodes#DOUBLE, Opcodes#NULL, or Opcodes#UNINITIALIZED_THIS, or the internal name of a class, or a Label designating a NEW instruction (for uninitialized types).

Returns:int

the abstract type corresponding to the given frame element type.

getAbstractTypeFromDescriptor back to summary

private static int getAbstractTypeFromDescriptor(final SymbolTable symbolTable, final String buffer, final int offset)

Returns the abstract type corresponding to the given type descriptor.

Parameters

symbolTable:SymbolTable: the type table to use to lookup and store type Symbol.
buffer:String: a string ending with a type descriptor.
offset:int: the start offset of the type descriptor in buffer.

Returns:int

the abstract type corresponding to the given type descriptor.

getAbstractTypeFromInternalName back to summary

pack-priv static int getAbstractTypeFromInternalName(final SymbolTable symbolTable, final String internalName)

Returns the abstract type corresponding to the internal name of a class.

Parameters

symbolTable:SymbolTable: the type table to use to lookup and store type Symbol.
internalName:String: the internal name of a class. This must not be an array type descriptor.

Returns:int

the abstract type value corresponding to the given internal name.

getConcreteOutputType

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private int getConcreteOutputType(final int abstractOutputType, final int numStack)

Computes the concrete output type corresponding to a given abstract output type.

Parameters

abstractOutputType:int: an abstract output type.
numStack:int: the size of the input stack, used to resolve abstract output types of STACK_KIND kind.

Returns:int

the concrete output type corresponding to 'abstractOutputType'.

getInitializedType back to summary

private int getInitializedType(final SymbolTable symbolTable, final int abstractType)

Returns the "initialized" abstract type corresponding to the given abstract type.

Parameters

symbolTable:SymbolTable: the type table to use to lookup and store type Symbol.
abstractType:int: an abstract type.

Returns:int

the REFERENCE_KIND abstract type corresponding to abstractType if it is UNINITIALIZED_THIS or an UNINITIALIZED_KIND or FORWARD_UNINITIALIZED_KIND abstract type for one of the types on which a constructor is invoked in the basic block. Otherwise returns abstractType.

getInputStackSize	back to summary
pack-priv final int getInputStackSize()

getLocal

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private int getLocal(final int localIndex)

Returns the abstract type stored at the given local variable index in the output frame.

Parameters

localIndex:int: the index of the local variable whose value must be returned.

Returns:int

the abstract type stored at the given local variable index in the output frame.

merge back to summary

pack-priv final boolean merge(final SymbolTable symbolTable, final Frame dstFrame, final int catchTypeIndex)

Merges the input frame of the given Frame with the input and output frames of this Frame. Returns true if the given frame has been changed by this operation (the input and output frames of this Frame are never changed).

Parameters

symbolTable:SymbolTable: the type table to use to lookup and store type Symbol.
dstFrame:Frame: the Frame whose input frame must be updated. This should be the frame of a successor, in the control flow graph, of the basic block corresponding to this frame.
catchTypeIndex:int: if 'frame' corresponds to an exception handler basic block, the type table index of the caught exception type, otherwise 0.

Returns:boolean

true if the input frame of 'frame' has been changed by this operation.

merge back to summary

private static boolean merge(final SymbolTable symbolTable, final int sourceType, final int[] dstTypes, final int dstIndex)

Merges the type at the given index in the given abstract type array with the given type. Returns true if the type array has been modified by this operation.

Parameters

symbolTable:SymbolTable: the type table to use to lookup and store type Symbol.
sourceType:int: the abstract type with which the abstract type array element must be merged. This type should be of CONSTANT_KIND, REFERENCE_KIND, UNINITIALIZED_KIND or FORWARD_UNINITIALIZED_KIND kind, with positive or null array dimensions.
dstTypes:int[]: an array of abstract types. These types should be of CONSTANT_KIND, REFERENCE_KIND, UNINITIALIZED_KIND or FORWARD_UNINITIALIZED_KIND kind, with positive or null array dimensions.
dstIndex:int: the index of the type that must be merged in dstTypes.

Returns:boolean

true if the type array has been modified by this operation.

pop

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private int pop()

Pops an abstract type from the output frame stack and returns its value.

Returns:int: the abstract type that has been popped from the output frame stack.

pop

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private void pop(final int elements)

Pops the given number of abstract types from the output frame stack.

Parameters

elements:int: the number of abstract types that must be popped.

pop

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private void pop(final String descriptor)

Pops as many abstract types from the output frame stack as described by the given descriptor.

Parameters

descriptor:String: a type or method descriptor (in which case its argument types are popped).

push

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private void push(final int abstractType)

Pushes the given abstract type on the output frame stack.

Parameters

abstractType:int: an abstract type.

push back to summary

private void push(final SymbolTable symbolTable, final String descriptor)

Pushes the abstract type corresponding to the given descriptor on the output frame stack.

Parameters

symbolTable:SymbolTable: the type table to use to lookup and store type Symbol.
descriptor:String: a type or method descriptor (in which case its return type is pushed).

putAbstractType back to summary

pack-priv static void putAbstractType(final SymbolTable symbolTable, final int abstractType, final ByteVector output)

Put the given abstract type in the given ByteVector, using the JVMS verification_type_info format used in StackMapTable attributes.

Parameters

symbolTable:SymbolTable: the type table to use to lookup and store type Symbol.
abstractType:int: an abstract type, restricted to Frame#CONSTANT_KIND, Frame#REFERENCE_KIND, Frame#UNINITIALIZED_KIND or Frame#FORWARD_UNINITIALIZED_KIND types.
output:ByteVector: where the abstract type must be put.

See Also

JVMS 4.7.4

setInputFrameFromApiFormat back to summary

pack-priv final void setInputFrameFromApiFormat(final SymbolTable symbolTable, final int numLocal, final Object[] local, final int numStack, final Object[] stack)

Sets the input frame from the given public API frame description.

Parameters

symbolTable:SymbolTable: the type table to use to lookup and store type Symbol.
numLocal:int: the number of local variables.
local:Object[]: the local variable types, described using the same format as in MethodVisitor#visitFrame.
numStack:int: the number of operand stack elements.
stack:Object[]: the operand stack types, described using the same format as in MethodVisitor#visitFrame.

setInputFrameFromDescriptor back to summary

pack-priv final void setInputFrameFromDescriptor(final SymbolTable symbolTable, final int access, final String descriptor, final int maxLocals)

Sets the input frame from the given method description. This method is used to initialize the first frame of a method, which is implicit (i.e. not stored explicitly in the StackMapTable attribute).

Parameters

symbolTable:SymbolTable: the type table to use to lookup and store type Symbol.
access:int: the method's access flags.
descriptor:String: the method descriptor.
maxLocals:int: the maximum number of local variables of the method.

setLocal

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private void setLocal(final int localIndex, final int abstractType)

Replaces the abstract type stored at the given local variable index in the output frame.

Parameters

localIndex:int: the index of the output frame local variable that must be set.
abstractType:int: the value that must be set.

pack-priv Class Frame

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail