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// ASM: a very small and fast Java bytecode manipulation framework
// Copyright (c) 2000-2011 INRIA, France Telecom
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
// 3. Neither the name of the copyright holders nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
// THE POSSIBILITY OF SUCH DAMAGE.
package net.bytebuddy.jar.asm;
/**
* 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 {@link 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 {@link #DIM_MASK} and a
* right shift of {@link #DIM_SHIFT}.
*
- the KIND field, stored in 4 bits, indicates the kind of VALUE used. These 4 bits can be
* retrieved with {@link #KIND_MASK} and, without any shift, must be equal to {@link
* #CONSTANT_KIND}, {@link #REFERENCE_KIND}, {@link #UNINITIALIZED_KIND}, {@link
* #FORWARD_UNINITIALIZED_KIND},{@link #LOCAL_KIND} or {@link #STACK_KIND}.
*
- the FLAGS field, stored in 2 bits, contains up to 2 boolean flags. Currently only one flag
* is defined, namely {@link #TOP_IF_LONG_OR_DOUBLE_FLAG}.
*
- the VALUE field, stored in the remaining 20 bits, contains either
*
* - one of the constants {@link #ITEM_TOP}, {@link #ITEM_ASM_BOOLEAN}, {@link
* #ITEM_ASM_BYTE}, {@link #ITEM_ASM_CHAR} or {@link #ITEM_ASM_SHORT}, {@link
* #ITEM_INTEGER}, {@link #ITEM_FLOAT}, {@link #ITEM_LONG}, {@link #ITEM_DOUBLE}, {@link
* #ITEM_NULL} or {@link #ITEM_UNINITIALIZED_THIS}, if KIND is equal to {@link
* #CONSTANT_KIND}.
*
- the index of a {@link Symbol#TYPE_TAG} {@link Symbol} in the type table of a {@link
* SymbolTable}, if KIND is equal to {@link #REFERENCE_KIND}.
*
- the index of an {@link Symbol#UNINITIALIZED_TYPE_TAG} {@link Symbol} in the type
* table of a {@link SymbolTable}, if KIND is equal to {@link #UNINITIALIZED_KIND}.
*
- the index of a {@link Symbol#FORWARD_UNINITIALIZED_TYPE_TAG} {@link Symbol} in the
* type table of a {@link SymbolTable}, if KIND is equal to {@link
* #FORWARD_UNINITIALIZED_KIND}.
*
- the index of a local variable in the input stack frame, if KIND is equal to {@link
* #LOCAL_KIND}.
*
- a position relatively to the top of the stack of the input stack frame, if KIND is
* equal to {@link #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 {@literal 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).
*
* @author Eric Bruneton
*/
class Frame {
// Constants used in the StackMapTable attribute.
// See https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.4.
static final int SAME_FRAME = 0;
static final int SAME_LOCALS_1_STACK_ITEM_FRAME = 64;
static final int RESERVED = 128;
static final int SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED = 247;
static final int CHOP_FRAME = 248;
static final int SAME_FRAME_EXTENDED = 251;
static final int APPEND_FRAME = 252;
static final int FULL_FRAME = 255;
static final int ITEM_TOP = 0;
static final int ITEM_INTEGER = 1;
static final int ITEM_FLOAT = 2;
static final int ITEM_DOUBLE = 3;
static final int ITEM_LONG = 4;
static final int ITEM_NULL = 5;
static final int ITEM_UNINITIALIZED_THIS = 6;
static final int ITEM_OBJECT = 7;
static final int ITEM_UNINITIALIZED = 8;
// Additional, ASM specific constants used in abstract types below.
private static final int ITEM_ASM_BOOLEAN = 9;
private static final int ITEM_ASM_BYTE = 10;
private static final int ITEM_ASM_CHAR = 11;
private static final int ITEM_ASM_SHORT = 12;
// The size and offset in bits of each field of an abstract type.
private static final int DIM_SIZE = 6;
private static final int KIND_SIZE = 4;
private static final int FLAGS_SIZE = 2;
private static final int VALUE_SIZE = 32 - DIM_SIZE - KIND_SIZE - FLAGS_SIZE;
private static final int DIM_SHIFT = KIND_SIZE + FLAGS_SIZE + VALUE_SIZE;
private static final int KIND_SHIFT = FLAGS_SIZE + VALUE_SIZE;
private static final int FLAGS_SHIFT = VALUE_SIZE;
// Bitmasks to get each field of an abstract type.
private static final int DIM_MASK = ((1 << DIM_SIZE) - 1) << DIM_SHIFT;
private static final int KIND_MASK = ((1 << KIND_SIZE) - 1) << KIND_SHIFT;
private static final int VALUE_MASK = (1 << VALUE_SIZE) - 1;
// Constants to manipulate the DIM field of an abstract type.
/** The constant to be added to an abstract type to get one with one more array dimension. */
private static final int ARRAY_OF = +1 << DIM_SHIFT;
/** The constant to be added to an abstract type to get one with one less array dimension. */
private static final int ELEMENT_OF = -1 << DIM_SHIFT;
// Possible values for the KIND field of an abstract type.
private static final int CONSTANT_KIND = 1 << KIND_SHIFT;
private static final int REFERENCE_KIND = 2 << KIND_SHIFT;
private static final int UNINITIALIZED_KIND = 3 << KIND_SHIFT;
private static final int FORWARD_UNINITIALIZED_KIND = 4 << KIND_SHIFT;
private static final int LOCAL_KIND = 5 << KIND_SHIFT;
private static final int STACK_KIND = 6 << KIND_SHIFT;
// Possible flags for the FLAGS field of an abstract type.
/**
* 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 TOP_IF_LONG_OR_DOUBLE_FLAG = 1 << FLAGS_SHIFT;
// Useful predefined abstract types (all the possible CONSTANT_KIND types).
private static final int TOP = CONSTANT_KIND | ITEM_TOP;
private static final int BOOLEAN = CONSTANT_KIND | ITEM_ASM_BOOLEAN;
private static final int BYTE = CONSTANT_KIND | ITEM_ASM_BYTE;
private static final int CHAR = CONSTANT_KIND | ITEM_ASM_CHAR;
private static final int SHORT = CONSTANT_KIND | ITEM_ASM_SHORT;
private static final int INTEGER = CONSTANT_KIND | ITEM_INTEGER;
private static final int FLOAT = CONSTANT_KIND | ITEM_FLOAT;
private static final int LONG = CONSTANT_KIND | ITEM_LONG;
private static final int DOUBLE = CONSTANT_KIND | ITEM_DOUBLE;
private static final int NULL = CONSTANT_KIND | ITEM_NULL;
private static final int UNINITIALIZED_THIS = CONSTANT_KIND | ITEM_UNINITIALIZED_THIS;
// -----------------------------------------------------------------------------------------------
// Instance fields
// -----------------------------------------------------------------------------------------------
/** The basic block to which these input and output stack map frames correspond. */
Label owner;
/** The input stack map frame locals. This is an array of abstract types. */
private int[] inputLocals;
/** The input stack map frame stack. This is an array of abstract types. */
private int[] inputStack;
/** The output stack map frame locals. This is an array of abstract types. */
private int[] outputLocals;
/** The output stack map frame stack. This is an array of abstract types. */
private int[] outputStack;
/**
* 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.
*/
private short outputStackStart;
/** The index of the top stack element in {@link #outputStack}. */
private short outputStackTop;
/** The number of types that are initialized in the basic block. See {@link #initializations}. */
private int initializationCount;
/**
* 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.
*/
private int[] initializations;
// -----------------------------------------------------------------------------------------------
// Constructor
// -----------------------------------------------------------------------------------------------
/**
* Constructs a new Frame.
*
* @param owner the basic block to which these input and output stack map frames correspond.
*/
Frame(final Label owner) {
this.owner = owner;
}
/**
* 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.
*
* @param frame The new frame value.
*/
final void copyFrom(final Frame frame) {
inputLocals = frame.inputLocals;
inputStack = frame.inputStack;
outputStackStart = 0;
outputLocals = frame.outputLocals;
outputStack = frame.outputStack;
outputStackTop = frame.outputStackTop;
initializationCount = frame.initializationCount;
initializations = frame.initializations;
}
// -----------------------------------------------------------------------------------------------
// Static methods to get abstract types from other type formats
// -----------------------------------------------------------------------------------------------
/**
* Returns the abstract type corresponding to the given public API frame element type.
*
* @param symbolTable the type table to use to lookup and store type {@link Symbol}.
* @param type a frame element type described using the same format as in {@link
* MethodVisitor#visitFrame}, i.e. either {@link Opcodes#TOP}, {@link Opcodes#INTEGER}, {@link
* Opcodes#FLOAT}, {@link Opcodes#LONG}, {@link Opcodes#DOUBLE}, {@link Opcodes#NULL}, or
* {@link Opcodes#UNINITIALIZED_THIS}, or the internal name of a class, or a Label designating
* a NEW instruction (for uninitialized types).
* @return the abstract type corresponding to the given frame element type.
*/
static int getAbstractTypeFromApiFormat(final SymbolTable symbolTable, final Object type) {
if (type instanceof Integer) {
return CONSTANT_KIND | ((Integer) type).intValue();
} else if (type instanceof String) {
String descriptor = Type.getObjectType((String) type).getDescriptor();
return getAbstractTypeFromDescriptor(symbolTable, descriptor, 0);
} else {
Label label = (Label) type;
if ((label.flags & Label.FLAG_RESOLVED) != 0) {
return UNINITIALIZED_KIND | symbolTable.addUninitializedType("", label.bytecodeOffset);
} else {
return FORWARD_UNINITIALIZED_KIND | symbolTable.addForwardUninitializedType("", label);
}
}
}
/**
* Returns the abstract type corresponding to the internal name of a class.
*
* @param symbolTable the type table to use to lookup and store type {@link Symbol}.
* @param internalName the internal name of a class. This must not be an array type
* descriptor.
* @return the abstract type value corresponding to the given internal name.
*/
static int getAbstractTypeFromInternalName(
final SymbolTable symbolTable, final String internalName) {
return REFERENCE_KIND | symbolTable.addType(internalName);
}
/**
* Returns the abstract type corresponding to the given type descriptor.
*
* @param symbolTable the type table to use to lookup and store type {@link Symbol}.
* @param buffer a string ending with a type descriptor.
* @param offset the start offset of the type descriptor in buffer.
* @return the abstract type corresponding to the given type descriptor.
*/
private static int getAbstractTypeFromDescriptor(
final SymbolTable symbolTable, final String buffer, final int offset) {
String internalName;
switch (buffer.charAt(offset)) {
case 'V':
return 0;
case 'Z':
case 'C':
case 'B':
case 'S':
case 'I':
return INTEGER;
case 'F':
return FLOAT;
case 'J':
return LONG;
case 'D':
return DOUBLE;
case 'L':
internalName = buffer.substring(offset + 1, buffer.length() - 1);
return REFERENCE_KIND | symbolTable.addType(internalName);
case '[':
int elementDescriptorOffset = offset + 1;
while (buffer.charAt(elementDescriptorOffset) == '[') {
++elementDescriptorOffset;
}
int typeValue;
switch (buffer.charAt(elementDescriptorOffset)) {
case 'Z':
typeValue = BOOLEAN;
break;
case 'C':
typeValue = CHAR;
break;
case 'B':
typeValue = BYTE;
break;
case 'S':
typeValue = SHORT;
break;
case 'I':
typeValue = INTEGER;
break;
case 'F':
typeValue = FLOAT;
break;
case 'J':
typeValue = LONG;
break;
case 'D':
typeValue = DOUBLE;
break;
case 'L':
internalName = buffer.substring(elementDescriptorOffset + 1, buffer.length() - 1);
typeValue = REFERENCE_KIND | symbolTable.addType(internalName);
break;
default:
throw new IllegalArgumentException(
"Invalid descriptor fragment: " + buffer.substring(elementDescriptorOffset));
}
return ((elementDescriptorOffset - offset) << DIM_SHIFT) | typeValue;
default:
throw new IllegalArgumentException("Invalid descriptor: " + buffer.substring(offset));
}
}
// -----------------------------------------------------------------------------------------------
// Methods related to the input frame
// -----------------------------------------------------------------------------------------------
/**
* 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).
*
* @param symbolTable the type table to use to lookup and store type {@link Symbol}.
* @param access the method's access flags.
* @param descriptor the method descriptor.
* @param maxLocals the maximum number of local variables of the method.
*/
final void setInputFrameFromDescriptor(
final SymbolTable symbolTable,
final int access,
final String descriptor,
final int maxLocals) {
inputLocals = new int[maxLocals];
inputStack = new int[0];
int inputLocalIndex = 0;
if ((access & Opcodes.ACC_STATIC) == 0) {
if ((access & Constants.ACC_CONSTRUCTOR) == 0) {
inputLocals[inputLocalIndex++] =
REFERENCE_KIND | symbolTable.addType(symbolTable.getClassName());
} else {
inputLocals[inputLocalIndex++] = UNINITIALIZED_THIS;
}
}
for (Type argumentType : Type.getArgumentTypes(descriptor)) {
int abstractType =
getAbstractTypeFromDescriptor(symbolTable, argumentType.getDescriptor(), 0);
inputLocals[inputLocalIndex++] = abstractType;
if (abstractType == LONG || abstractType == DOUBLE) {
inputLocals[inputLocalIndex++] = TOP;
}
}
while (inputLocalIndex < maxLocals) {
inputLocals[inputLocalIndex++] = TOP;
}
}
/**
* Sets the input frame from the given public API frame description.
*
* @param symbolTable the type table to use to lookup and store type {@link Symbol}.
* @param numLocal the number of local variables.
* @param local the local variable types, described using the same format as in {@link
* MethodVisitor#visitFrame}.
* @param numStack the number of operand stack elements.
* @param stack the operand stack types, described using the same format as in {@link
* MethodVisitor#visitFrame}.
*/
final void setInputFrameFromApiFormat(
final SymbolTable symbolTable,
final int numLocal,
final Object[] local,
final int numStack,
final Object[] stack) {
int inputLocalIndex = 0;
for (int i = 0; i < numLocal; ++i) {
inputLocals[inputLocalIndex++] = getAbstractTypeFromApiFormat(symbolTable, local[i]);
if (local[i] == Opcodes.LONG || local[i] == Opcodes.DOUBLE) {
inputLocals[inputLocalIndex++] = TOP;
}
}
while (inputLocalIndex < inputLocals.length) {
inputLocals[inputLocalIndex++] = TOP;
}
int numStackTop = 0;
for (int i = 0; i < numStack; ++i) {
if (stack[i] == Opcodes.LONG || stack[i] == Opcodes.DOUBLE) {
++numStackTop;
}
}
inputStack = new int[numStack + numStackTop];
int inputStackIndex = 0;
for (int i = 0; i < numStack; ++i) {
inputStack[inputStackIndex++] = getAbstractTypeFromApiFormat(symbolTable, stack[i]);
if (stack[i] == Opcodes.LONG || stack[i] == Opcodes.DOUBLE) {
inputStack[inputStackIndex++] = TOP;
}
}
outputStackTop = 0;
initializationCount = 0;
}
final int getInputStackSize() {
return inputStack.length;
}
// -----------------------------------------------------------------------------------------------
// Methods related to the output frame
// -----------------------------------------------------------------------------------------------
/**
* Returns the abstract type stored at the given local variable index in the output frame.
*
* @param localIndex the index of the local variable whose value must be returned.
* @return the abstract type stored at the given local variable index in the output frame.
*/
private int getLocal(final int localIndex) {
if (outputLocals == null || localIndex >= outputLocals.length) {
// If this local has never been assigned in this basic block, it is still equal to its value
// in the input frame.
return LOCAL_KIND | localIndex;
} else {
int abstractType = outputLocals[localIndex];
if (abstractType == 0) {
// If this local has never been assigned in this basic block, so it is still equal to its
// value in the input frame.
abstractType = outputLocals[localIndex] = LOCAL_KIND | localIndex;
}
return abstractType;
}
}
/**
* Replaces the abstract type stored at the given local variable index in the output frame.
*
* @param localIndex the index of the output frame local variable that must be set.
* @param abstractType the value that must be set.
*/
private void setLocal(final int localIndex, final int abstractType) {
// Create and/or resize the output local variables array if necessary.
if (outputLocals == null) {
outputLocals = new int[10];
}
int outputLocalsLength = outputLocals.length;
if (localIndex >= outputLocalsLength) {
int[] newOutputLocals = new int[Math.max(localIndex + 1, 2 * outputLocalsLength)];
System.arraycopy(outputLocals, 0, newOutputLocals, 0, outputLocalsLength);
outputLocals = newOutputLocals;
}
// Set the local variable.
outputLocals[localIndex] = abstractType;
}
/**
* Pushes the given abstract type on the output frame stack.
*
* @param abstractType an abstract type.
*/
private void push(final int abstractType) {
// Create and/or resize the output stack array if necessary.
if (outputStack == null) {
outputStack = new int[10];
}
int outputStackLength = outputStack.length;
if (outputStackTop >= outputStackLength) {
int[] newOutputStack = new int[Math.max(outputStackTop + 1, 2 * outputStackLength)];
System.arraycopy(outputStack, 0, newOutputStack, 0, outputStackLength);
outputStack = newOutputStack;
}
// Pushes the abstract type on the output stack.
outputStack[outputStackTop++] = abstractType;
// Updates the maximum size reached by the output stack, if needed (note that this size is
// relative to the input stack size, which is not known yet).
short outputStackSize = (short) (outputStackStart + outputStackTop);
if (outputStackSize > owner.outputStackMax) {
owner.outputStackMax = outputStackSize;
}
}
/**
* Pushes the abstract type corresponding to the given descriptor on the output frame stack.
*
* @param symbolTable the type table to use to lookup and store type {@link Symbol}.
* @param descriptor a type or method descriptor (in which case its return type is pushed).
*/
private void push(final SymbolTable symbolTable, final String descriptor) {
int typeDescriptorOffset =
descriptor.charAt(0) == '(' ? Type.getReturnTypeOffset(descriptor) : 0;
int abstractType = getAbstractTypeFromDescriptor(symbolTable, descriptor, typeDescriptorOffset);
if (abstractType != 0) {
push(abstractType);
if (abstractType == LONG || abstractType == DOUBLE) {
push(TOP);
}
}
}
/**
* Pops an abstract type from the output frame stack and returns its value.
*
* @return the abstract type that has been popped from the output frame stack.
*/
private int pop() {
if (outputStackTop > 0) {
return outputStack[--outputStackTop];
} else {
// If the output frame stack is empty, pop from the input stack.
return STACK_KIND | -(--outputStackStart);
}
}
/**
* Pops the given number of abstract types from the output frame stack.
*
* @param elements the number of abstract types that must be popped.
*/
private void pop(final int elements) {
if (outputStackTop >= elements) {
outputStackTop -= elements;
} else {
// If the number of elements to be popped is greater than the number of elements in the output
// stack, clear it, and pop the remaining elements from the input stack.
outputStackStart -= elements - outputStackTop;
outputStackTop = 0;
}
}
/**
* Pops as many abstract types from the output frame stack as described by the given descriptor.
*
* @param descriptor a type or method descriptor (in which case its argument types are popped).
*/
private void pop(final String descriptor) {
char firstDescriptorChar = descriptor.charAt(0);
if (firstDescriptorChar == '(') {
pop((Type.getArgumentsAndReturnSizes(descriptor) >> 2) - 1);
} else if (firstDescriptorChar == 'J' || firstDescriptorChar == 'D') {
pop(2);
} else {
pop(1);
}
}
// -----------------------------------------------------------------------------------------------
// Methods to handle uninitialized types
// -----------------------------------------------------------------------------------------------
/**
* Adds an abstract type to the list of types on which a constructor is invoked in the basic
* block.
*
* @param abstractType an abstract type on a which a constructor is invoked.
*/
private void addInitializedType(final int abstractType) {
// Create and/or resize the initializations array if necessary.
if (initializations == null) {
initializations = new int[2];
}
int initializationsLength = initializations.length;
if (initializationCount >= initializationsLength) {
int[] newInitializations =
new int[Math.max(initializationCount + 1, 2 * initializationsLength)];
System.arraycopy(initializations, 0, newInitializations, 0, initializationsLength);
initializations = newInitializations;
}
// Store the abstract type.
initializations[initializationCount++] = abstractType;
}
/**
* Returns the "initialized" abstract type corresponding to the given abstract type.
*
* @param symbolTable the type table to use to lookup and store type {@link Symbol}.
* @param abstractType an abstract type.
* @return 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.
*/
private int getInitializedType(final SymbolTable symbolTable, final int abstractType) {
if (abstractType == UNINITIALIZED_THIS
|| (abstractType & (DIM_MASK | KIND_MASK)) == UNINITIALIZED_KIND
|| (abstractType & (DIM_MASK | KIND_MASK)) == FORWARD_UNINITIALIZED_KIND) {
for (int i = 0; i < initializationCount; ++i) {
int initializedType = initializations[i];
int dim = initializedType & DIM_MASK;
int kind = initializedType & KIND_MASK;
int value = initializedType & VALUE_MASK;
if (kind == LOCAL_KIND) {
initializedType = dim + inputLocals[value];
} else if (kind == STACK_KIND) {
initializedType = dim + inputStack[inputStack.length - value];
}
if (abstractType == initializedType) {
if (abstractType == UNINITIALIZED_THIS) {
return REFERENCE_KIND | symbolTable.addType(symbolTable.getClassName());
} else {
return REFERENCE_KIND
| symbolTable.addType(symbolTable.getType(abstractType & VALUE_MASK).value);
}
}
}
}
return abstractType;
}
// -----------------------------------------------------------------------------------------------
// Main method, to simulate the execution of each instruction on the output frame
// -----------------------------------------------------------------------------------------------
/**
* Simulates the action of the given instruction on the output stack frame.
*
* @param opcode the opcode of the instruction.
* @param arg the numeric operand of the instruction, if any.
* @param argSymbol the Symbol operand of the instruction, if any.
* @param symbolTable the type table to use to lookup and store type {@link Symbol}.
*/
void execute(
final int opcode, final int arg, final Symbol argSymbol, final SymbolTable symbolTable) {
// Abstract types popped from the stack or read from local variables.
int abstractType1;
int abstractType2;
int abstractType3;
int abstractType4;
switch (opcode) {
case Opcodes.NOP:
case Opcodes.INEG:
case Opcodes.LNEG:
case Opcodes.FNEG:
case Opcodes.DNEG:
case Opcodes.I2B:
case Opcodes.I2C:
case Opcodes.I2S:
case Opcodes.GOTO:
case Opcodes.RETURN:
break;
case Opcodes.ACONST_NULL:
push(NULL);
break;
case Opcodes.ICONST_M1:
case Opcodes.ICONST_0:
case Opcodes.ICONST_1:
case Opcodes.ICONST_2:
case Opcodes.ICONST_3:
case Opcodes.ICONST_4:
case Opcodes.ICONST_5:
case Opcodes.BIPUSH:
case Opcodes.SIPUSH:
case Opcodes.ILOAD:
push(INTEGER);
break;
case Opcodes.LCONST_0:
case Opcodes.LCONST_1:
case Opcodes.LLOAD:
push(LONG);
push(TOP);
break;
case Opcodes.FCONST_0:
case Opcodes.FCONST_1:
case Opcodes.FCONST_2:
case Opcodes.FLOAD:
push(FLOAT);
break;
case Opcodes.DCONST_0:
case Opcodes.DCONST_1:
case Opcodes.DLOAD:
push(DOUBLE);
push(TOP);
break;
case Opcodes.LDC:
switch (argSymbol.tag) {
case Symbol.CONSTANT_INTEGER_TAG:
push(INTEGER);
break;
case Symbol.CONSTANT_LONG_TAG:
push(LONG);
push(TOP);
break;
case Symbol.CONSTANT_FLOAT_TAG:
push(FLOAT);
break;
case Symbol.CONSTANT_DOUBLE_TAG:
push(DOUBLE);
push(TOP);
break;
case Symbol.CONSTANT_CLASS_TAG:
push(REFERENCE_KIND | symbolTable.addType("java/lang/Class"));
break;
case Symbol.CONSTANT_STRING_TAG:
push(REFERENCE_KIND | symbolTable.addType("java/lang/String"));
break;
case Symbol.CONSTANT_METHOD_TYPE_TAG:
push(REFERENCE_KIND | symbolTable.addType("java/lang/invoke/MethodType"));
break;
case Symbol.CONSTANT_METHOD_HANDLE_TAG:
push(REFERENCE_KIND | symbolTable.addType("java/lang/invoke/MethodHandle"));
break;
case Symbol.CONSTANT_DYNAMIC_TAG:
push(symbolTable, argSymbol.value);
break;
default:
throw new AssertionError();
}
break;
case Opcodes.ALOAD:
push(getLocal(arg));
break;
case Opcodes.LALOAD:
case Opcodes.D2L:
pop(2);
push(LONG);
push(TOP);
break;
case Opcodes.DALOAD:
case Opcodes.L2D:
pop(2);
push(DOUBLE);
push(TOP);
break;
case Opcodes.AALOAD:
pop(1);
abstractType1 = pop();
push(abstractType1 == NULL ? abstractType1 : ELEMENT_OF + abstractType1);
break;
case Opcodes.ISTORE:
case Opcodes.FSTORE:
case Opcodes.ASTORE:
abstractType1 = pop();
setLocal(arg, abstractType1);
if (arg > 0) {
int previousLocalType = getLocal(arg - 1);
if (previousLocalType == LONG || previousLocalType == DOUBLE) {
setLocal(arg - 1, TOP);
} else if ((previousLocalType & KIND_MASK) == LOCAL_KIND
|| (previousLocalType & KIND_MASK) == STACK_KIND) {
// The type of the previous local variable is not known yet, but if it later appears
// to be LONG or DOUBLE, we should then use TOP instead.
setLocal(arg - 1, previousLocalType | TOP_IF_LONG_OR_DOUBLE_FLAG);
}
}
break;
case Opcodes.LSTORE:
case Opcodes.DSTORE:
pop(1);
abstractType1 = pop();
setLocal(arg, abstractType1);
setLocal(arg + 1, TOP);
if (arg > 0) {
int previousLocalType = getLocal(arg - 1);
if (previousLocalType == LONG || previousLocalType == DOUBLE) {
setLocal(arg - 1, TOP);
} else if ((previousLocalType & KIND_MASK) == LOCAL_KIND
|| (previousLocalType & KIND_MASK) == STACK_KIND) {
// The type of the previous local variable is not known yet, but if it later appears
// to be LONG or DOUBLE, we should then use TOP instead.
setLocal(arg - 1, previousLocalType | TOP_IF_LONG_OR_DOUBLE_FLAG);
}
}
break;
case Opcodes.IASTORE:
case Opcodes.BASTORE:
case Opcodes.CASTORE:
case Opcodes.SASTORE:
case Opcodes.FASTORE:
case Opcodes.AASTORE:
pop(3);
break;
case Opcodes.LASTORE:
case Opcodes.DASTORE:
pop(4);
break;
case Opcodes.POP:
case Opcodes.IFEQ:
case Opcodes.IFNE:
case Opcodes.IFLT:
case Opcodes.IFGE:
case Opcodes.IFGT:
case Opcodes.IFLE:
case Opcodes.IRETURN:
case Opcodes.FRETURN:
case Opcodes.ARETURN:
case Opcodes.TABLESWITCH:
case Opcodes.LOOKUPSWITCH:
case Opcodes.ATHROW:
case Opcodes.MONITORENTER:
case Opcodes.MONITOREXIT:
case Opcodes.IFNULL:
case Opcodes.IFNONNULL:
pop(1);
break;
case Opcodes.POP2:
case Opcodes.IF_ICMPEQ:
case Opcodes.IF_ICMPNE:
case Opcodes.IF_ICMPLT:
case Opcodes.IF_ICMPGE:
case Opcodes.IF_ICMPGT:
case Opcodes.IF_ICMPLE:
case Opcodes.IF_ACMPEQ:
case Opcodes.IF_ACMPNE:
case Opcodes.LRETURN:
case Opcodes.DRETURN:
pop(2);
break;
case Opcodes.DUP:
abstractType1 = pop();
push(abstractType1);
push(abstractType1);
break;
case Opcodes.DUP_X1:
abstractType1 = pop();
abstractType2 = pop();
push(abstractType1);
push(abstractType2);
push(abstractType1);
break;
case Opcodes.DUP_X2:
abstractType1 = pop();
abstractType2 = pop();
abstractType3 = pop();
push(abstractType1);
push(abstractType3);
push(abstractType2);
push(abstractType1);
break;
case Opcodes.DUP2:
abstractType1 = pop();
abstractType2 = pop();
push(abstractType2);
push(abstractType1);
push(abstractType2);
push(abstractType1);
break;
case Opcodes.DUP2_X1:
abstractType1 = pop();
abstractType2 = pop();
abstractType3 = pop();
push(abstractType2);
push(abstractType1);
push(abstractType3);
push(abstractType2);
push(abstractType1);
break;
case Opcodes.DUP2_X2:
abstractType1 = pop();
abstractType2 = pop();
abstractType3 = pop();
abstractType4 = pop();
push(abstractType2);
push(abstractType1);
push(abstractType4);
push(abstractType3);
push(abstractType2);
push(abstractType1);
break;
case Opcodes.SWAP:
abstractType1 = pop();
abstractType2 = pop();
push(abstractType1);
push(abstractType2);
break;
case Opcodes.IALOAD:
case Opcodes.BALOAD:
case Opcodes.CALOAD:
case Opcodes.SALOAD:
case Opcodes.IADD:
case Opcodes.ISUB:
case Opcodes.IMUL:
case Opcodes.IDIV:
case Opcodes.IREM:
case Opcodes.IAND:
case Opcodes.IOR:
case Opcodes.IXOR:
case Opcodes.ISHL:
case Opcodes.ISHR:
case Opcodes.IUSHR:
case Opcodes.L2I:
case Opcodes.D2I:
case Opcodes.FCMPL:
case Opcodes.FCMPG:
pop(2);
push(INTEGER);
break;
case Opcodes.LADD:
case Opcodes.LSUB:
case Opcodes.LMUL:
case Opcodes.LDIV:
case Opcodes.LREM:
case Opcodes.LAND:
case Opcodes.LOR:
case Opcodes.LXOR:
pop(4);
push(LONG);
push(TOP);
break;
case Opcodes.FALOAD:
case Opcodes.FADD:
case Opcodes.FSUB:
case Opcodes.FMUL:
case Opcodes.FDIV:
case Opcodes.FREM:
case Opcodes.L2F:
case Opcodes.D2F:
pop(2);
push(FLOAT);
break;
case Opcodes.DADD:
case Opcodes.DSUB:
case Opcodes.DMUL:
case Opcodes.DDIV:
case Opcodes.DREM:
pop(4);
push(DOUBLE);
push(TOP);
break;
case Opcodes.LSHL:
case Opcodes.LSHR:
case Opcodes.LUSHR:
pop(3);
push(LONG);
push(TOP);
break;
case Opcodes.IINC:
setLocal(arg, INTEGER);
break;
case Opcodes.I2L:
case Opcodes.F2L:
pop(1);
push(LONG);
push(TOP);
break;
case Opcodes.I2F:
pop(1);
push(FLOAT);
break;
case Opcodes.I2D:
case Opcodes.F2D:
pop(1);
push(DOUBLE);
push(TOP);
break;
case Opcodes.F2I:
case Opcodes.ARRAYLENGTH:
case Opcodes.INSTANCEOF:
pop(1);
push(INTEGER);
break;
case Opcodes.LCMP:
case Opcodes.DCMPL:
case Opcodes.DCMPG:
pop(4);
push(INTEGER);
break;
case Opcodes.JSR:
case Opcodes.RET:
throw new IllegalArgumentException("JSR/RET are not supported with computeFrames option");
case Opcodes.GETSTATIC:
push(symbolTable, argSymbol.value);
break;
case Opcodes.PUTSTATIC:
pop(argSymbol.value);
break;
case Opcodes.GETFIELD:
pop(1);
push(symbolTable, argSymbol.value);
break;
case Opcodes.PUTFIELD:
pop(argSymbol.value);
pop();
break;
case Opcodes.INVOKEVIRTUAL:
case Opcodes.INVOKESPECIAL:
case Opcodes.INVOKESTATIC:
case Opcodes.INVOKEINTERFACE:
pop(argSymbol.value);
if (opcode != Opcodes.INVOKESTATIC) {
abstractType1 = pop();
if (opcode == Opcodes.INVOKESPECIAL && argSymbol.name.charAt(0) == '<') {
addInitializedType(abstractType1);
}
}
push(symbolTable, argSymbol.value);
break;
case Opcodes.INVOKEDYNAMIC:
pop(argSymbol.value);
push(symbolTable, argSymbol.value);
break;
case Opcodes.NEW:
push(UNINITIALIZED_KIND | symbolTable.addUninitializedType(argSymbol.value, arg));
break;
case Opcodes.NEWARRAY:
pop();
switch (arg) {
case Opcodes.T_BOOLEAN:
push(ARRAY_OF | BOOLEAN);
break;
case Opcodes.T_CHAR:
push(ARRAY_OF | CHAR);
break;
case Opcodes.T_BYTE:
push(ARRAY_OF | BYTE);
break;
case Opcodes.T_SHORT:
push(ARRAY_OF | SHORT);
break;
case Opcodes.T_INT:
push(ARRAY_OF | INTEGER);
break;
case Opcodes.T_FLOAT:
push(ARRAY_OF | FLOAT);
break;
case Opcodes.T_DOUBLE:
push(ARRAY_OF | DOUBLE);
break;
case Opcodes.T_LONG:
push(ARRAY_OF | LONG);
break;
default:
throw new IllegalArgumentException();
}
break;
case Opcodes.ANEWARRAY:
String arrayElementType = argSymbol.value;
pop();
if (arrayElementType.charAt(0) == '[') {
push(symbolTable, '[' + arrayElementType);
} else {
push(ARRAY_OF | REFERENCE_KIND | symbolTable.addType(arrayElementType));
}
break;
case Opcodes.CHECKCAST:
String castType = argSymbol.value;
pop();
if (castType.charAt(0) == '[') {
push(symbolTable, castType);
} else {
push(REFERENCE_KIND | symbolTable.addType(castType));
}
break;
case Opcodes.MULTIANEWARRAY:
pop(arg);
push(symbolTable, argSymbol.value);
break;
default:
throw new IllegalArgumentException();
}
}
// -----------------------------------------------------------------------------------------------
// Frame merging methods, used in the second step of the stack map frame computation algorithm
// -----------------------------------------------------------------------------------------------
/**
* Computes the concrete output type corresponding to a given abstract output type.
*
* @param abstractOutputType an abstract output type.
* @param numStack the size of the input stack, used to resolve abstract output types of
* STACK_KIND kind.
* @return the concrete output type corresponding to 'abstractOutputType'.
*/
private int getConcreteOutputType(final int abstractOutputType, final int numStack) {
int dim = abstractOutputType & DIM_MASK;
int kind = abstractOutputType & KIND_MASK;
if (kind == LOCAL_KIND) {
// By definition, a LOCAL_KIND type designates the concrete type of a local variable at
// the beginning of the basic block corresponding to this frame (which is known when
// this method is called, but was not when the abstract type was computed).
int concreteOutputType = dim + inputLocals[abstractOutputType & VALUE_MASK];
if ((abstractOutputType & TOP_IF_LONG_OR_DOUBLE_FLAG) != 0
&& (concreteOutputType == LONG || concreteOutputType == DOUBLE)) {
concreteOutputType = TOP;
}
return concreteOutputType;
} else if (kind == STACK_KIND) {
// By definition, a STACK_KIND type designates the concrete type of a local variable at
// the beginning of the basic block corresponding to this frame (which is known when
// this method is called, but was not when the abstract type was computed).
int concreteOutputType = dim + inputStack[numStack - (abstractOutputType & VALUE_MASK)];
if ((abstractOutputType & TOP_IF_LONG_OR_DOUBLE_FLAG) != 0
&& (concreteOutputType == LONG || concreteOutputType == DOUBLE)) {
concreteOutputType = TOP;
}
return concreteOutputType;
} else {
return abstractOutputType;
}
}
/**
* Merges the input frame of the given {@link Frame} with the input and output frames of this
* {@link Frame}. Returns {@literal true} if the given frame has been changed by this operation
* (the input and output frames of this {@link Frame} are never changed).
*
* @param symbolTable the type table to use to lookup and store type {@link Symbol}.
* @param dstFrame the {@link 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.
* @param catchTypeIndex if 'frame' corresponds to an exception handler basic block, the type
* table index of the caught exception type, otherwise 0.
* @return {@literal true} if the input frame of 'frame' has been changed by this operation.
*/
final boolean merge(
final SymbolTable symbolTable, final Frame dstFrame, final int catchTypeIndex) {
boolean frameChanged = false;
// Compute the concrete types of the local variables at the end of the basic block corresponding
// to this frame, by resolving its abstract output types, and merge these concrete types with
// those of the local variables in the input frame of dstFrame.
int numLocal = inputLocals.length;
int numStack = inputStack.length;
if (dstFrame.inputLocals == null) {
dstFrame.inputLocals = new int[numLocal];
frameChanged = true;
}
for (int i = 0; i < numLocal; ++i) {
int concreteOutputType;
if (outputLocals != null && i < outputLocals.length) {
int abstractOutputType = outputLocals[i];
if (abstractOutputType == 0) {
// If the local variable has never been assigned in this basic block, it is equal to its
// value at the beginning of the block.
concreteOutputType = inputLocals[i];
} else {
concreteOutputType = getConcreteOutputType(abstractOutputType, numStack);
}
} else {
// If the local variable has never been assigned in this basic block, it is equal to its
// value at the beginning of the block.
concreteOutputType = inputLocals[i];
}
// concreteOutputType might be an uninitialized type from the input locals or from the input
// stack. However, if a constructor has been called for this class type in the basic block,
// then this type is no longer uninitialized at the end of basic block.
if (initializations != null) {
concreteOutputType = getInitializedType(symbolTable, concreteOutputType);
}
frameChanged |= merge(symbolTable, concreteOutputType, dstFrame.inputLocals, i);
}
// If dstFrame is an exception handler block, it can be reached from any instruction of the
// basic block corresponding to this frame, in particular from the first one. Therefore, the
// input locals of dstFrame should be compatible (i.e. merged) with the input locals of this
// frame (and the input stack of dstFrame should be compatible, i.e. merged, with a one
// element stack containing the caught exception type).
if (catchTypeIndex > 0) {
for (int i = 0; i < numLocal; ++i) {
frameChanged |= merge(symbolTable, inputLocals[i], dstFrame.inputLocals, i);
}
if (dstFrame.inputStack == null) {
dstFrame.inputStack = new int[1];
frameChanged = true;
}
frameChanged |= merge(symbolTable, catchTypeIndex, dstFrame.inputStack, 0);
return frameChanged;
}
// Compute the concrete types of the stack operands at the end of the basic block corresponding
// to this frame, by resolving its abstract output types, and merge these concrete types with
// those of the stack operands in the input frame of dstFrame.
int numInputStack = inputStack.length + outputStackStart;
if (dstFrame.inputStack == null) {
dstFrame.inputStack = new int[numInputStack + outputStackTop];
frameChanged = true;
}
// First, do this for the stack operands that have not been popped in the basic block
// corresponding to this frame, and which are therefore equal to their value in the input
// frame (except for uninitialized types, which may have been initialized).
for (int i = 0; i < numInputStack; ++i) {
int concreteOutputType = inputStack[i];
if (initializations != null) {
concreteOutputType = getInitializedType(symbolTable, concreteOutputType);
}
frameChanged |= merge(symbolTable, concreteOutputType, dstFrame.inputStack, i);
}
// Then, do this for the stack operands that have pushed in the basic block (this code is the
// same as the one above for local variables).
for (int i = 0; i < outputStackTop; ++i) {
int abstractOutputType = outputStack[i];
int concreteOutputType = getConcreteOutputType(abstractOutputType, numStack);
if (initializations != null) {
concreteOutputType = getInitializedType(symbolTable, concreteOutputType);
}
frameChanged |=
merge(symbolTable, concreteOutputType, dstFrame.inputStack, numInputStack + i);
}
return frameChanged;
}
/**
* Merges the type at the given index in the given abstract type array with the given type.
* Returns {@literal true} if the type array has been modified by this operation.
*
* @param symbolTable the type table to use to lookup and store type {@link Symbol}.
* @param sourceType the abstract type with which the abstract type array element must be merged.
* This type should be of {@link #CONSTANT_KIND}, {@link #REFERENCE_KIND}, {@link
* #UNINITIALIZED_KIND} or {@link #FORWARD_UNINITIALIZED_KIND} kind, with positive or
* {@literal null} array dimensions.
* @param dstTypes an array of abstract types. These types should be of {@link #CONSTANT_KIND},
* {@link #REFERENCE_KIND}, {@link #UNINITIALIZED_KIND} or {@link #FORWARD_UNINITIALIZED_KIND}
* kind, with positive or {@literal null} array dimensions.
* @param dstIndex the index of the type that must be merged in dstTypes.
* @return {@literal true} if the type array has been modified by this operation.
*/
private static boolean merge(
final SymbolTable symbolTable,
final int sourceType,
final int[] dstTypes,
final int dstIndex) {
int dstType = dstTypes[dstIndex];
if (dstType == sourceType) {
// If the types are equal, merge(sourceType, dstType) = dstType, so there is no change.
return false;
}
int srcType = sourceType;
if ((sourceType & ~DIM_MASK) == NULL) {
if (dstType == NULL) {
return false;
}
srcType = NULL;
}
if (dstType == 0) {
// If dstTypes[dstIndex] has never been assigned, merge(srcType, dstType) = srcType.
dstTypes[dstIndex] = srcType;
return true;
}
int mergedType;
if ((dstType & DIM_MASK) != 0 || (dstType & KIND_MASK) == REFERENCE_KIND) {
// If dstType is a reference type of any array dimension.
if (srcType == NULL) {
// If srcType is the NULL type, merge(srcType, dstType) = dstType, so there is no change.
return false;
} else if ((srcType & (DIM_MASK | KIND_MASK)) == (dstType & (DIM_MASK | KIND_MASK))) {
// If srcType has the same array dimension and the same kind as dstType.
if ((dstType & KIND_MASK) == REFERENCE_KIND) {
// If srcType and dstType are reference types with the same array dimension,
// merge(srcType, dstType) = dim(srcType) | common super class of srcType and dstType.
mergedType =
(srcType & DIM_MASK)
| REFERENCE_KIND
| symbolTable.addMergedType(srcType & VALUE_MASK, dstType & VALUE_MASK);
} else {
// If srcType and dstType are array types of equal dimension but different element types,
// merge(srcType, dstType) = dim(srcType) - 1 | java/lang/Object.
int mergedDim = ELEMENT_OF + (srcType & DIM_MASK);
mergedType = mergedDim | REFERENCE_KIND | symbolTable.addType("java/lang/Object");
}
} else if ((srcType & DIM_MASK) != 0 || (srcType & KIND_MASK) == REFERENCE_KIND) {
// If srcType is any other reference or array type,
// merge(srcType, dstType) = min(srcDdim, dstDim) | java/lang/Object
// where srcDim is the array dimension of srcType, minus 1 if srcType is an array type
// with a non reference element type (and similarly for dstDim).
int srcDim = srcType & DIM_MASK;
if (srcDim != 0 && (srcType & KIND_MASK) != REFERENCE_KIND) {
srcDim = ELEMENT_OF + srcDim;
}
int dstDim = dstType & DIM_MASK;
if (dstDim != 0 && (dstType & KIND_MASK) != REFERENCE_KIND) {
dstDim = ELEMENT_OF + dstDim;
}
mergedType =
Math.min(srcDim, dstDim) | REFERENCE_KIND | symbolTable.addType("java/lang/Object");
} else {
// If srcType is any other type, merge(srcType, dstType) = TOP.
mergedType = TOP;
}
} else if (dstType == NULL) {
// If dstType is the NULL type, merge(srcType, dstType) = srcType, or TOP if srcType is not a
// an array type or a reference type.
mergedType =
(srcType & DIM_MASK) != 0 || (srcType & KIND_MASK) == REFERENCE_KIND ? srcType : TOP;
} else {
// If dstType is any other type, merge(srcType, dstType) = TOP whatever srcType.
mergedType = TOP;
}
if (mergedType != dstType) {
dstTypes[dstIndex] = mergedType;
return true;
}
return false;
}
// -----------------------------------------------------------------------------------------------
// Frame output methods, to generate StackMapFrame attributes
// -----------------------------------------------------------------------------------------------
/**
* Makes the given {@link MethodWriter} visit the input frame of this {@link Frame}. The visit is
* done with the {@link MethodWriter#visitFrameStart}, {@link MethodWriter#visitAbstractType} and
* {@link MethodWriter#visitFrameEnd} methods.
*
* @param methodWriter the {@link MethodWriter} that should visit the input frame of this {@link
* Frame}.
*/
final void accept(final MethodWriter methodWriter) {
// Compute the number of locals, ignoring TOP types that are just after a LONG or a DOUBLE, and
// all trailing TOP types.
int[] localTypes = inputLocals;
int numLocal = 0;
int numTrailingTop = 0;
int i = 0;
while (i < localTypes.length) {
int localType = localTypes[i];
i += (localType == LONG || localType == DOUBLE) ? 2 : 1;
if (localType == TOP) {
numTrailingTop++;
} else {
numLocal += numTrailingTop + 1;
numTrailingTop = 0;
}
}
// Compute the stack size, ignoring TOP types that are just after a LONG or a DOUBLE.
int[] stackTypes = inputStack;
int numStack = 0;
i = 0;
while (i < stackTypes.length) {
int stackType = stackTypes[i];
i += (stackType == LONG || stackType == DOUBLE) ? 2 : 1;
numStack++;
}
// Visit the frame and its content.
int frameIndex = methodWriter.visitFrameStart(owner.bytecodeOffset, numLocal, numStack);
i = 0;
while (numLocal-- > 0) {
int localType = localTypes[i];
i += (localType == LONG || localType == DOUBLE) ? 2 : 1;
methodWriter.visitAbstractType(frameIndex++, localType);
}
i = 0;
while (numStack-- > 0) {
int stackType = stackTypes[i];
i += (stackType == LONG || stackType == DOUBLE) ? 2 : 1;
methodWriter.visitAbstractType(frameIndex++, stackType);
}
methodWriter.visitFrameEnd();
}
/**
* Put the given abstract type in the given ByteVector, using the JVMS verification_type_info
* format used in StackMapTable attributes.
*
* @param symbolTable the type table to use to lookup and store type {@link Symbol}.
* @param abstractType an abstract type, restricted to {@link Frame#CONSTANT_KIND}, {@link
* Frame#REFERENCE_KIND}, {@link Frame#UNINITIALIZED_KIND} or {@link
* Frame#FORWARD_UNINITIALIZED_KIND} types.
* @param output where the abstract type must be put.
* @see JVMS
* 4.7.4
*/
static void putAbstractType(
final SymbolTable symbolTable, final int abstractType, final ByteVector output) {
int arrayDimensions = (abstractType & Frame.DIM_MASK) >> DIM_SHIFT;
if (arrayDimensions == 0) {
int typeValue = abstractType & VALUE_MASK;
switch (abstractType & KIND_MASK) {
case CONSTANT_KIND:
output.putByte(typeValue);
break;
case REFERENCE_KIND:
output
.putByte(ITEM_OBJECT)
.putShort(symbolTable.addConstantClass(symbolTable.getType(typeValue).value).index);
break;
case UNINITIALIZED_KIND:
output.putByte(ITEM_UNINITIALIZED).putShort((int) symbolTable.getType(typeValue).data);
break;
case FORWARD_UNINITIALIZED_KIND:
output.putByte(ITEM_UNINITIALIZED);
symbolTable.getForwardUninitializedLabel(typeValue).put(output);
break;
default:
throw new AssertionError();
}
} else {
// Case of an array type, we need to build its descriptor first.
StringBuilder typeDescriptor = new StringBuilder();
while (arrayDimensions-- > 0) {
typeDescriptor.append('[');
}
if ((abstractType & KIND_MASK) == REFERENCE_KIND) {
typeDescriptor
.append('L')
.append(symbolTable.getType(abstractType & VALUE_MASK).value)
.append(';');
} else {
switch (abstractType & VALUE_MASK) {
case Frame.ITEM_ASM_BOOLEAN:
typeDescriptor.append('Z');
break;
case Frame.ITEM_ASM_BYTE:
typeDescriptor.append('B');
break;
case Frame.ITEM_ASM_CHAR:
typeDescriptor.append('C');
break;
case Frame.ITEM_ASM_SHORT:
typeDescriptor.append('S');
break;
case Frame.ITEM_INTEGER:
typeDescriptor.append('I');
break;
case Frame.ITEM_FLOAT:
typeDescriptor.append('F');
break;
case Frame.ITEM_LONG:
typeDescriptor.append('J');
break;
case Frame.ITEM_DOUBLE:
typeDescriptor.append('D');
break;
default:
throw new AssertionError();
}
}
output
.putByte(ITEM_OBJECT)
.putShort(symbolTable.addConstantClass(typeDescriptor.toString()).index);
}
}
}