Interface DiscontinuedInstruction.RetInstruction

All Superinterfaces:

ClassFileElement, CodeElement, DiscontinuedInstruction, Instruction

Enclosing interface:

DiscontinuedInstruction

public static sealed interface DiscontinuedInstruction.RetInstruction
extends DiscontinuedInstruction

Models return from 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_RET. Delivered as a CodeElement when traversing the elements of a CodeModel.

A return from subroutine instruction is composite:

RetInstruction(int slot)

where slot must be u2.

astore series of instructions store a returnAddress value to a local variable slot, making the slot usable by a return from subroutine instruction.

API Note:

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

See Java Virtual Machine Specification:

6.5.ret ret

Since:

24

See Also:

• Opcode.Kind.DISCONTINUED_RET
• StackMapTableAttribute

Nested Class Summary

Nested classes/interfaces declared in interface DiscontinuedInstruction

DiscontinuedInstruction.JsrInstruction, DiscontinuedInstruction.RetInstruction

Modifier and Type	Interface	Description
static interface	DiscontinuedInstruction.JsrInstruction	Models jump subroutine instructions discontinued from the code array of a Code attribute since class file major version 51 (JVMS 4.9.1).
static interface	DiscontinuedInstruction.RetInstruction	Models return from subroutine instructions discontinued from the code array of a Code attribute since class file major version 51 (JVMS 4.9.1).

Method Summary

Modifier and Type	Method	Description
static DiscontinuedInstruction.RetInstruction	of(int slot)	Returns a return from subroutine instruction.
static DiscontinuedInstruction.RetInstruction	of(Opcode op, int slot)	Returns a return from subroutine instruction.
int	slot()	Returns the local variable slot with return address.

Methods declared in interface Instruction

opcode, sizeInBytes

Modifier and Type	Method	Description
Opcode	opcode()	Returns the operation of this instruction.
int	sizeInBytes()	Returns the size in bytes of this instruction.

Method Details

slot

int slot()

Returns the local variable slot with return address. It is a u2 value.

Returns:

the local variable slot with return address

of

static DiscontinuedInstruction.RetInstruction of(Opcode op,
 int slot)

Returns a return from subroutine instruction.

slot must be u1 for ret, or u2 for wide ret.

API Note:

The explicit op argument allows creating wide ret instructions with slot in the range of regular ret instructions.

Parameters:

op - the opcode for the specific type of return from subroutine instruction, which must be of kind Opcode.Kind.DISCONTINUED_RET

slot - the local variable slot to load return address from

Returns:

a return from subroutine instruction

Throws:

IllegalArgumentException - if the opcode kind is not Opcode.Kind.DISCONTINUED_RET or if slot is out of range

of

static DiscontinuedInstruction.RetInstruction of(int slot)

Returns a return from subroutine instruction.

slot must be u2.

Parameters:

slot - the local variable slot to load return address from

Returns:

a return from subroutine instruction

Throws:

IllegalArgumentException - if slot is not u2