trait ConditionalBranchInstructionLike extends ControlTransferInstructionLike
Common super class of all conditional branch instructions.
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Abstract Value Members
- abstract def indexOfNextInstruction(currentPC: Int, modifiedByWide: Boolean): Int
The index of the next instruction in the code array.
The index of the next instruction in the code array.
- Definition Classes
- InstructionLike
- abstract def isIsomorphic(thisPC: Int, otherPC: Int)(implicit code: Code): Boolean
Determines if this instruction is isomorphic to the given instruction.
Determines if this instruction is isomorphic to the given instruction.
Two instructions are isomporphic if they access the same operand and register values and if the instructions have the same bytecode representation, except of (A) (potential) padding bytes and (B) the branch offset of JSR(_W) instructions. In the first case the branch offsets are corrected by the number of padding bytes and in the second case the absolute addresses are compared (i.e., whether both instructions call the same subroutine).
For example, an
aload_0
instruction is only isomorphic to anotheraload_0
instruction and is not isomorphic to anaload(0)
instruction – though the runtime effect is the same. However, a LOOKUPSWITCH (TABLESWITCH) instruction is considered isomorphic to another respective instruction if the only difference is the number of padding bytes. Furthermore, two JSR(_W) instructions are isomorphic if and only if they jump to the same subroutine.- Definition Classes
- InstructionLike
- Note
The number of padding bytes is generally calculated by
(otherPC % 4) - (thisPC %4)
(==="padding other" - "padding this"
) and should be added to the branch offsets of this(XYZ)switch
instruction when the branch targets are compared to the other instructions branchoffsets.// "padding b" - "padding a" // === (3 - (bPC % 4)) - (3 - (aPC % 4)) // === (aPC % 4) - (bPC %4)
,this.isIsomorphic(
thisPC
,thisPC
) is alwaystrue
- abstract def mnemonic: String
The mnemonic of the instruction as defined by the JVM specification.
The mnemonic of the instruction as defined by the JVM specification.
- Definition Classes
- InstructionLike
- abstract def opcode: Int
The opcode of the instruction as defined by the JVM specification.
The opcode of the instruction as defined by the JVM specification. The opcode is a value in the range [0..255].
- Definition Classes
- InstructionLike
- abstract def operandCount: Int
The number of operand values popped from the operand stack.
- abstract def stackSlotsChange: Int
The number of stack slots pushed or popped by this instruction.
The number of stack slots pushed or popped by this instruction.
- Definition Classes
- InstructionLike
- Note
Overall, each DUP instruction always pushes the same number of stack slots. Only the number of values that are processed may depend on the stack layout.
- abstract def toString(currentPC: Int): String
Returns a string representation of this instruction.
Returns a string representation of this instruction. If this instruction is a (conditional) jump instruction, then the PCs of the target instructions are given absolute address.
- currentPC
The program counter of this instruction. Used to resolve relative jump targets.
- Definition Classes
- InstructionLike
Concrete Value Members
- final def expressionResult: NoExpression.type
Returns the location – Stack, Register or NoExpression – where the value computed by this instruction is stored.
Returns the location – Stack, Register or NoExpression – where the value computed by this instruction is stored. In this case an instruction is only considered to be an expression if it puts a value on the stack or in a register that is the result of some kind of computation; i.e., just copying, duplicating or moving a value between the stack and the registers is not considered to be an expression.
- Definition Classes
- ControlTransferInstructionLike → InstructionLike
- Note
The CHECKCAST instruction is special in the sense that it just inspects the top-most value.
- final def indexOfReadLocal: Int
The index of the local (variable)/register that is read is returned.
The index of the local (variable)/register that is read is returned. This method is only defined if readsLocal returns
true
.- Definition Classes
- ConditionalBranchInstructionLike → InstructionLike
- final def indexOfWrittenLocal: Int
The index of the local (variable)/register that is written.
The index of the local (variable)/register that is written. This method is only defined if writesLocal returns
true
.- Definition Classes
- ConditionalBranchInstructionLike → InstructionLike
- def isAthrow: Boolean
- Definition Classes
- InstructionLike
- final def isControlTransferInstruction: Boolean
- Definition Classes
- ControlTransferInstructionLike → InstructionLike
- def isLoadConstantInstruction: Boolean
- Definition Classes
- InstructionLike
- def isMonitorInstruction: Boolean
- Definition Classes
- InstructionLike
- def isRET: Boolean
- Definition Classes
- InstructionLike
- def isReturnInstruction: Boolean
- Definition Classes
- InstructionLike
- final def jvmExceptions: List[ObjectType]
The exceptions that may be thrown by the JVM at runtime if the execution of this instruction fails.
The exceptions that may be thrown by the JVM at runtime if the execution of this instruction fails. I.e., these are neither exceptions that are explicitly created and then thrown by user code nor errors that may arise due to an invalid code base (in particular
LinkageError
s). However,OutOfMemoryError
s are possible.- Definition Classes
- ControlTransferInstructionLike → InstructionLike
- Note
The returned types always precisely describe the thrown exception; they are not upper bounds. All instructions – except of the InvocationInstructions and the ATHROW$ instruction – will always either succeed, throw a linkage time related exception or throw one of the specified exceptions.
- final def mayThrowExceptions: Boolean
Returns
true
if the evaluation of the instruction may lead to some runtime exception.Returns
true
if the evaluation of the instruction may lead to some runtime exception. For example, in case of INVOKESTATICjvmExceptions
will return an empty list. However, in general the called method may throw an arbitrary exception.Errors (such as LinkageError) related to invalid projects are not considered.
- Definition Classes
- ControlTransferInstructionLike → InstructionLike
- final def numberOfPoppedOperands(ctg: (Int) => ComputationalTypeCategory): Int
The number of values that are popped from the operand stack.
The number of values that are popped from the operand stack. Here, long and double values are also counted as one value though they use two stack slots. E.g., IADD (integer add) and LADD (long add) both pop two values and push one value.
- ctg
A function that returns the computational type category of the value on the operand stack with a given value index. E.g., The top value on the operand stack has index '0' and may occupy one (for category 1 values) or two stack slots (for category 2 values.)
- Definition Classes
- ConditionalBranchInstructionLike → InstructionLike
- Note
In case of some of the StackManagementInstruction the number of popped values is not fixed. In that case the number depends on the concrete layout of the operand stack. E.g., the POP2 instruction may just pop one categeory 2 value (of type
long
ordouble
) or two category 1 values.
- final def numberOfPushedOperands(ctg: (Int) => ComputationalTypeCategory): Int
The number of values that are put onto the operand stack.
The number of values that are put onto the operand stack. Here, long and double values are also counted as one value though they use two stack slots. E.g., IADD (integer add) and LADD (long add) both pop two values and push one value.
- ctg
A function that returns the computational type category of the value on the operand stack with a given value index. The top value on the operand stack has index '0' and may occupy one (for category 1 values) or two stack slots (for category 2 values.)
- Definition Classes
- ConditionalBranchInstructionLike → InstructionLike
- Note
In case of some of the StackManagementInstruction this number is not fixed. In that case the number depends on the concrete layout of the operand stack. E.g., the DUP2 instruction may just duplicate one categeory 2 value (result is 1) (of type long or double) or two category 1 values (result is 2).
- final def readsLocal: Boolean
Returns
true
if this instruction reads/uses a local variable.Returns
true
if this instruction reads/uses a local variable.- Definition Classes
- ConditionalBranchInstructionLike → InstructionLike
- final def writesLocal: Boolean
Returns
true
if this instruction writes/updates a local variable.Returns
true
if this instruction writes/updates a local variable.- Definition Classes
- ConditionalBranchInstructionLike → InstructionLike