iii.3.46-leave-length.md

III.3.46 leave.<length> – exit a protected region of code

Format	Assembly Format	Description
DD <int32>	leave target	Exit a protected region of code.
DE <int8>	leave.s target	Exit a protected region of code, short form.

Stack Transition:

…, →

Description:

The leave instruction unconditionally transfers control to target. target is represented as a signed offset (4 bytes for leave, 1 byte for leave.s) from the beginning of the instruction following the current instruction.

The leave instruction is similar to the br instruction, but the former can be used to exit a try, filter, or catch block whereas the ordinary branch instructions can only be used in such a block to transfer control within it. The leave instruction empties the evaluation stack and ensures that the appropriate surrounding finally blocks are executed.

It is not valid to use a leave instruction to exit a finally block. To ease code generation for exception handlers it is valid from within a catch block to use a leave instruction to transfer control to any instruction within the associated try block.

The leave instruction can be used to exit multiple nested blocks (see Partition I).

If an instruction has one or more prefix codes, control can only be transferred to the first of these prefixes.

Exceptions:

None.

Correctness:

Correct CIL requires the computed destination lie within the current method.

Verifiability:

See §III.1.8 for details.