Instances of this class contain information about the subroutines
found in a code array of a method.
This implementation considers the top-level (the instructions
reachable without a JSR or JSR_W starting off from the first
instruction in a code array of a method) being a special subroutine;
see getTopLevel() for that.
Please note that the definition of subroutines in the Java Virtual
Machine Specification, Second Edition is somewhat incomplete.
Therefore, JustIce uses an own, more rigid notion.
Basically, a subroutine is a piece of code that starts at the target
of a JSR of JSR_W instruction and ends at a corresponding RET
instruction. Note also that the control flow of a subroutine
may be complex and non-linear; and that subroutines may be nested.
JustIce also mandates subroutines not to be protected by exception
handling code (for the sake of control flow predictability).
To understand JustIce's notion of subroutines, please read
TODO: refer to the paper.
Returns the Subroutine object associated with the given
leader (that is, the first instruction of the subroutine).
You must not use this to get the top-level instructions
modeled as a Subroutine object.
Returns the subroutine object associated with the
given instruction. This is a costly operation, you
should consider using getSubroutine(InstructionHandle).
Returns 'null' if the given InstructionHandle lies
in so-called 'dead code', i.e. code that can never
For easy handling, the piece of code that is not a
subroutine, the top-level, is also modeled as a Subroutine
It is a special Subroutine object where you must not invoke
getEnteringJsrInstructions() or getLeavingRET().