Interface DiscontinuedInstruction.JsrInstruction

All Superinterfaces:

ClassFileElement, CodeElement, DiscontinuedInstruction, Instruction

Enclosing interface:

DiscontinuedInstruction

public static sealed interface DiscontinuedInstruction.JsrInstruction
extends DiscontinuedInstruction

Models jump subroutine instructions discontinued from the code array of a Code attribute since class file major version 51 (JVMS 4.9.1). Corresponding opcodes have a kind of Opcode.Kind.DISCONTINUED_JSR. Delivered as a CodeElement when traversing the elements of a CodeModel.

A jump subroutine instruction is composite:

JsrInstruction(Label target)

Due to physical restrictions, jsr instructions cannot encode labels too far away in the list of code elements. In such cases, the ClassFile.ShortJumpsOption controls how an invalid jsr instruction model is written by a CodeBuilder.

Jump subroutine instructions push a returnAddress value to the operand stack, and astore series of instructions can then store this value to a local variable slot.

API Note:

Jump subroutine instructions are discontinued to enforce verification by type checking (JVMS 4.10.1) using the StackMapTable attribute.

Since:

24

See Also:

• Opcode.Kind.DISCONTINUED_JSR
• StackMapTableAttribute

Nested Class Summary

Nested classes/interfaces declared in interface java.lang.classfile.instruction.DiscontinuedInstruction

DiscontinuedInstruction.JsrInstruction, DiscontinuedInstruction.RetInstruction

Method Summary

Modifier and Type	Method	Description
static DiscontinuedInstruction.JsrInstruction	of(Label target)	Returns a jump subroutine instruction.
static DiscontinuedInstruction.JsrInstruction	of(Opcode op, Label target)	Returns a jump subroutine instruction.
Label	target()	Returns the target of the jump subroutine instruction.

Methods declared in interface java.lang.classfile.Instruction

opcode, sizeInBytes

Method Details

target

Label target()

Returns the target of the jump subroutine instruction.

Returns:

the target of the jump subroutine instruction

of

static DiscontinuedInstruction.JsrInstruction of(Opcode op,
 Label target)

Returns a jump subroutine instruction.

API Note:

The explicit op argument allows creating jsr_w instructions to avoid short jumps.

Parameters:

op - the opcode for the specific type of jump subroutine instruction, which must be of kind Opcode.Kind.DISCONTINUED_JSR

target - target label of the subroutine

Returns:

a jump subroutine instruction

Throws:

IllegalArgumentException - if the opcode kind is not Opcode.Kind.DISCONTINUED_JSR.

of

static DiscontinuedInstruction.JsrInstruction of(Label target)

Returns a jump subroutine instruction.

Parameters:

target - target label of the subroutine

Returns:

a jump subroutine instruction