=head1 NAME

core.ops - Core Opcodes


=cut

=head1 DESCRIPTION

Parrot's core library of ops.

Core operations are primarily flow control and interpreter
introspection.

When making changes to any ops file, run C<make bootstrap-ops> to regenerate
all generated ops files.


=cut

=head2 Basic ops

These are the fundamental operations.
Please note: These opcodes must not be moved; they must have
exactly these opcode numbers. Opcodes ending with underscores are for
internal use only; don't emit these opcodes.

=over 4


=cut

=item B<end>()

Halts the interpreter. See also B<exit>.


=cut

=item B<noop>()

Does nothing other than waste an iota of time and 32 bits of bytecode space.

=item B<check_events>()

Check the event queue and run event handlers if there are unhandled events.
Note: This opcode is mainly for testing. It should not be necessary to ever
use it explicitly.

=item B<check_events__>()

Check the event queue and run event handlers if there are unhandled events.
Note: Do B<not> use this opcode. It is for internal use only.

=item B<load_bytecode>(in STR)

Load Parrot bytecode from file $1, and search the library path to locate the
file. Automatically triggers :load functions if the file found is a .pbc. If
it is a .pir or a .pasm, the file is compiled first and the :init subs are
triggered instead. Nothing is returned.

=item B<load_bytecode>(out PMC, in STR)

Load Parrot bytecode from file $2, searching the library path to locate the
file. Returns a new PackfileView in $1. Does not perform any automatic
initialization. Use the PackfileView PMC interface to introspect and perform
actions on it.


=cut

=item B<load_language>(in STR)

Load the compiler libraries for a language $1. Search the library path to
locate the main compiler file in the standard locations.


=cut

=back


=cut

=head2 Control flow

The control flow opcodes check conditions and manage program flow.

=over 4


=cut

=item B<branch>(in LABEL)

Branch forward or backward by the amount in $1.


=cut

=item B<local_branch>(invar PMC, in LABEL)

Go to the location specified by the label in $2. Push the current location onto
the stack passed in $1 for later returning.


=cut

=item B<local_return>(invar PMC)

Pop the location off the top of the call stack and go there.


=cut

=item B<jump>(in LABEL)

Jump to the address held in register $1.


=cut

=back


=cut

=head2 Conditional branch operations

These operations perform a conditional relative branch. If the condition is
met, the branch happens.  Otherwise control falls to the next operation.

=over 4


=cut

=item B<if>(invar INT, inconst LABEL)

=item B<if>(invar NUM, inconst LABEL)

=item B<if>(invar PMC, inconst LABEL)

=item B<if>(invar STR, inconst LABEL)

Check register $1. If true, branch by $2.


=cut

=item B<unless>(invar INT, inconst LABEL)

=item B<unless>(invar NUM, inconst LABEL)

=item B<unless>(invar PMC, inconst LABEL)

=item B<unless>(invar STR, inconst LABEL)

Check register $1. If false, branch by $2.


=cut

=back


=cut

=head2 Subroutine operations

These operations are used to generate and call subroutines and
continuations.

=over 4


=cut

=item B<invokecc>(invar PMC)

Call the subroutine in $1 and generate a new return continuation, if needed.
For example, a NCI subroutine which executes code in some C library will not
create a continuation, nor will anything but the first call to a coroutine.

=item B<invoke>(invar PMC, invar PMC)

Call the subroutine in $1 and use continuation $2.

=item B<yield>()

Yield results from a coroutine.

=item B<tailcall>(invar PMC)

Call the subroutine in $1 and use the current continuation as the subs
continuation.

=item B<returncc>()

Return from the sub or method via the current continuation.

=item B<capture_lex>(invar PMC)

Capture the current lexical state of the inner subroutine PMC.

=item B<newclosure>(out PMC, invar PMC)

Create a closure of the given subroutine PMC by cloning the sub's state.


=cut

=back

=head2 Function argument opcode

Implementations of function argument and params handling

=over 4

=item B<set_args>(inconst PMC /* , ... */)

Define arguments for the next function call.

=item B<get_results>(inconst PMC /* , ... */)

Define return values for the next function call.

=item B<get_params>(inconst PMC /* , ... */)

Define function parameters for this subroutine.

=item B<set_returns>(inconst PMC /* , ... */)

Define return results for the subroutine return statement.

For all of these opcodes the passed invar PMC constant is the string
representation of a FixedIntegerArray with one flag word per argument.
The flags are documented currently in F<include/parrot/enums.h> only.

After this argument a variable amount of arguments must follow according
to the elements of the signature array.


=cut

=item B<set_result_info>(in PMC)

Set result_info. See also C<result_info>.


=cut

=item B<result_info>(out PMC)

Returns the get_results signature PMC of the caller. This PMC is a
FixedIntegerPMCArray. The number of elements of this PMC is equal to the number
of return values that are expected.  The individual bits per entry are
specified in F<docs/pdds/pdd03_calling_conventions.pod>.


=cut

=back

=head2 Address manipulation

=for clarity


=cut

=over 4

=item B<set_addr>(out INT, inconst LABEL)

Sets register $1 to the current address plus the offset $2.

=item B<set_addr>(invar PMC, inconst LABEL)

Sets PMC in register $1 to the current address plus the offset $2.

=item B<set_addr>(invar PMC, invar LABEL)

Sets PMC in register $1 to the absolute address $2 obtained from B<get_addr>.

=item B<get_addr>(out INT, invar PMC)

Sets $1 to the absolute address of the Sub PMC $2.


=cut

=back


=cut

=head2 Concurrency operations

=over 4

=item B<schedule>(invar PMC)

Register a task with the concurrency scheduler. Details about the task are
stored within the task PMC.


=cut

=item B<schedule_local>(invar PMC)

Like schedule but execute it on the current thread.


=cut

=item B<addhandler>(invar PMC)

Add an event or exception handler to the concurrency scheduler. Details about
the handler are stored within the handler PMC.


=cut

=back


=cut

=head2 Exception handling

=over 4

=item B<push_eh>(inconst LABEL)

Create an exception handler for the given catch label and push it onto
the exception handler stack.

=item B<push_eh>(invar PMC)

Push an invokable PMC onto the exception handler stack.

=item B<pop_eh>()

Pop the most recently placed exception off the handler stack.

=item B<throw>(invar PMC)

Throw the exception in $1 with current continuation.

=item B<throw>(invar PMC, invar PMC)

Throw the exception in $1 with continuation from $2.

=item B<rethrow>(invar PMC)

Only valid inside an exception handler. Rethrow the exception $1.

=item B<count_eh>(out INT)

Get a count of currently active exception handlers on the stack.

=item B<die>(in STR)

=item B<die>(in PMC)

Die with message $1

=item B<die>(in INT, in INT)

Die with severity $1 and error $2. If severity is .EXCEPT_DOOMED,
call _exit($2). The latter isn't catchable.

=item B<exit>(in INT)

Exit the interpreter with exit_status $1. If you want to communicate an
extended exit status, create an exception with severity B<EXCEPT_exit>
and throw it.

=item B<finalize>(in PMC)

Finalize exception handling, freeing any information needed to resume
the handled exception, like inner runloops.
$1 is the Exception handled or the ExceptionHandler that is handling it.

=item B<pop_upto_eh>(in PMC)

Pops all exception handlers upto the one indicated by $1. Like with the
finalize op, $1 can either be the handled Exception or the ExceptionHandler
handling it. Also, you should not resume Exceptions after pop_upto_eh
or finalize has been called. This limitation may be fixed in a future
version of parrot. Also note that the specified exception handler
is not popped.

=item B<peek_exception>(out PMC)

Returns the caught exception without clearing the call object. This is
currently needed because HLL authors use get_params to fetch the exception,
but get_params clears the call object. So we can't use get_params in PCT
to get the exception object without disturbing the HLL code.
This op will be removed again when PCT offers another mechansim to get
the exception and the HLLs switched to it.


=cut

=back


=cut

=head2 Interpreter operations

These operations inspect or modify the interpreter itself, possibly
affecting its subsequent operation.

=over 4


=cut

=item B<debug>(in INT)

If $1 is zero, turn off debugging. Otherwise turn debug flag $1 on.


=cut

=item B<bounds>(in INT)

If $1 is zero, turn off byte code bounds checking. Otherwise turn it on.


=cut

=item B<profile>(in INT)

If $1 is zero, turn off profiling. Otherwise turn it on.


=cut

=item B<trace>(in INT)

If $1 is zero, turn off tracing. Otherwise turn trace flag $1 on.


=cut

=item B<gc_debug>(in INT)

If $1 is zero, turn off GC_DEBUG. Otherwise turn it on.


=cut

=item B<interpinfo>

Fetch some piece of information about the interpreter and put it in $1.
Possible values for $2 are defined in F<runtime/parrot/include/interpinfo.pasm>.
The valid constants for each return value are (excluding the .INTERPINFO_
prefix):

=over 4

=item B<interpinfo>(out INT, in INT)

TOTAL_MEM_ALLOC, TOTAL_MEM_USED, GC_MARK_RUNS, GC_COLLECT_RUNS, ACTIVE_PMCS,
ACTIVE_BUFFERS, TOTAL_PMCS, TOTAL_BUFFERS, HEADER_ALLOCS_SINCE_COLLECT,
MEM_ALLOCS_SINCE_COLLECT, TOTAL_COPIED, IMPATIENT_PMCS, GC_LAZY_MARK_RUNS,
EXTENDED_PMCS, CURRENT_RUNCORE, PARROT_INTSIZE, PARROT_FLOATSIZE, PARROT_POINTERSIZE,
PARROT_INTMAX, PARROT_INTMIN

=item B<interpinfo>(out PMC, in INT)

CURRENT_SUB, CURRENT_CONT, CURRENT_OBJECT, CURRENT_LEXPAD

=item B<interpinfo>(out STR, in INT)

EXECUTABLE_FULLNAME, EXECUTABLE_BASENAME, RUNTIME_PREFIX, CURRENT_RUNCORE, PARROT_OS,
PARROT_OS_VERSION, PARROT_OS_VERSION_NUMBER, CPU_ARCH, CPU_TYPE

=back


=cut

=item B<warningson>(in INT)

Turns on warnings categories. Categories already turned on will stay on.
Initial setting is currently all warnings off.  Include F<warnings.pasm> to
access the categories. Refer to that file for the current list of warnings
available.

=over 4

=back

To turn on multiple categories, OR the category numbers together.


=cut

=item B<warningsoff>(in INT)

Turns off warnings categories.  Categories already turned off will
stay off.  See the documentation for B<warningson> for category
numbers.


=cut

=item B<errorson>(in INT)

Turns on error categories. Categories already turned on will stay on.  To
access these from PASM, include F<errors.pasm>.  The current categories are:

=over 4

=item .PARROT_ERRORS_OVERFLOW_FLAG

When performing arithmetic on Integer PMCs, throw a math overflow exception
instead of promoting to BigInt. This flag does not pertain to native integers,
which are never promoted. Default: off.

=item .PARROT_ERRORS_PARAM_COUNT_FLAG

Throw an exception on an argument versus parameter count mismatch. Default: on.

=item .PARROT_ERRORS_RESULT_COUNT_FLAG

Throw an exception on a return versus result count mismatch. Default: off.

=item .PARROT_ERRORS_ALL_FLAG

=back

To turn on multiple categories, OR the category numbers together.


=cut

=item B<errorsoff>(in INT)

Turns off errors categories.  Categories already turned off will
stay off.  See the documentation for B<errorson> for category
numbers.


=cut

=item B<set_runcore>(in STR)

Switch the current runcore to the one with the specified name.
Needs to be an op, as we need to restart the runops() call.
You can get the name of the current runcore with the interpinfo op.


=cut

=item B<runinterp>(invar PMC, in LABEL)

Run the code starting at offset $2 within interpreter $1.

=item B<getinterp>(out PMC)

Get the current ParrotInterpreter.


=cut

=back


=cut

=head2 Garbage Collection

Opcodes that interact with the GC subsystem.

=over 4


=cut

=item B<sweep>(inconst INT)

Triggers a GC run, based on the value of $1, where:

=over

=item * 0

Trigger a GC run only if there are things that have flagged themselves as
really needing to be collected.

=item * 1

Trigger a GC run unconditionally.

=back


=cut

=item B<collect>()

Trigger a garbage collection.


=cut

=item B<sweepoff>()

Disable GC runs. (Nestable)


=cut

=item B<sweepon>()

Re-enable GC runs.


=cut

=item B<collectoff>()

Disable GC runs (nestable).


=cut

=item B<collecton>()

Re-enable GC.


=cut

=item B<needs_destroy>(invar PMC)

Mark the PMC wanting destruction as soon as possible, for example
when unused during the lazy sweep, triggered by C<sweep 0>.


=cut

=back

=head2 Native Call Interface

Opcodes for interfacing with C functions in shared libraries.

=over 4


=cut

=item B<loadlib>(out PMC, in STR)

=item B<loadlib>(out PMC, in STR, in PMC)

Load a dynamic link library named $2 and store it in $1. $3, if
provided, controls library loading and initialization; currently,
we expect a bitmask accessible as an integer.  Bit definitions are
accessible from PASM if F<dlopenflags.pasm> is included.  The current
bits are:

=over 4

=item PARROT_DLOPEN_GLOBAL

Make any symbols in the library accessible to other libraries loaded.

=back

=item B<dlfunc>(out PMC, invar PMC, in STR, in STR)

=item B<dlfunc>(out PMC, invar PMC, in STR, invar PMC)

Look up symbol $3 in library $2 with signature $4, and put the
corresponding sub object in $1. Note that you need the signature so we
can build or find an appropriate thunking function.

=item B<dlvar>(out PMC, invar PMC, in STR)

Look up symbol $3 in library $2. We assume that this is actually a
variable address rather than a function address, and build an
UnManagedStruct PMC and stick the address into its data pointer.

=item B<compreg>(out PMC, in STR)

Get the compiler object for source type $2.  The returned compiler
object should provide a C<compile> method for translating code
in the source type.  However, some Parrot compilers such as
C<PIR> and C<PASM> currently return a sub that is to be
invoked directly on the source.

=item B<compreg>(in STR, invar PMC)

Register $2 as the compiler object for source type $1.

=item B<new_callback>(out PMC, invar PMC, invar PMC, in STR)

Create a callback stub $1 for PASM subroutine $2 with userdata $3 and
callback function signature $4. Only 2 argument signatures with
signature chars I<U[1iscpt]> or I<[1iscpt]U>  are handled currently.
But these cover a lot of callback signatures. Please note that the
userdata PMC I<U> has to be handled transparently by the caller of
the callback function.


=cut

=back


=cut

=head2 Annotations operations

These operations relate to bytecode annotations.

=over 4


=cut

=item B<annotations>(out PMC)

Gets all bytecode annotations in effect at the current point, in a Hash.
If there are none, returns an empty Hash.


=cut

=item B<annotations>(out PMC, in STR)

Gets the bytecode annotation with the given name that is in effect at the
current point. Returns PMCNULL if there is none.


=cut

=back


=cut

=head1 COPYRIGHT

Copyright (C) 2001-2012, Parrot Foundation.

=head1 LICENSE

This program is free software. It is subject to the same license
as the Parrot interpreter itself.


=cut

