3 emitter functions are needed only for emitcpy, and so we can #if them
out when compiling with emitcpy support.
Also remove unused SETUP_LOOP bytecode.
Closed over variables are now passed on the stack, instead of creating a
tuple and passing that. This way memory for the closed over variables
can be allocated within the closure object itself. See issue #510 for
background.
On stmhal, computed gotos make the binary about 1k bigger, but makes it
run faster, and we have the room, so why not. All tests pass on
pyboard using computed gotos.
Things get tricky when using the nlr code to catch exceptions. Need to
ensure that the variables (stack layout) in the exception handler are
the same as in the bit protected by the exception handler.
Prior to this patch there were a few bugs. 1) The constant
mp_const_MemoryError_obj was being preloaded to a specific location on
the stack at the start of the function. But this location on the stack
was being overwritten in the opcode loop (since it didn't think that
variable would ever be referenced again), and so when an exception
occurred, the variable holding the address of MemoryError was corrupt.
2) The FOR_ITER opcode detection in the exception handler used sp, which
may or may not contain the right value coming out of the main opcode
loop.
With this patch there is a clear separation of variables used in the
opcode loop and in the exception handler (should fix issue (2) above).
Furthermore, nlr_raise is no longer used in the opcode loop. Instead,
it jumps directly into the exception handler. This tells the C compiler
more about the possible code flow, and means that it should have the
same stack layout for the exception handler. This should fix issue (1)
above. Indeed, the generated (ARM) assembler has been checked explicitly,
and with 'goto exception_handler', the problem with &MemoryError is
fixed.
This may now fix problems with rge-sm, and probably many other subtle
bugs yet to show themselves. Incidentally, rge-sm now passes on
pyboard (with a reduced range of integration)!
Main lesson: nlr is tricky. Don't use nlr_push unless you know what you
are doing! Luckily, it's not used in many places. Using nlr_raise/jump
is fine.
Attempt to address issue #386. unique_code_id's have been removed and
replaced with a pointer to the "raw code" information. This pointer is
stored in the actual byte code (aligned, so the GC can trace it), so
that raw code (ie byte code, native code and inline assembler) is kept
only for as long as it is needed. In memory it's now like a tree: the
outer module's byte code points directly to its children's raw code. So
when the outer code gets freed, if there are no remaining functions that
need the raw code, then the children's code gets freed as well.
This is pretty much like CPython does it, except that CPython stores
indexes in the byte code rather than machine pointers. These indices
index the per-function constant table in order to find the relevant
code.
This is necessary to catch all cases where locals are referenced before
assignment. We still keep the _0, _1, _2 versions of LOAD_FAST to help
reduced the byte code size in RAM.
Addresses issue #457.
This simplifies the compiler a little, since now it can do 1 pass over
a function declaration, to determine default arguments. I would have
done this originally, but CPython 3.3 somehow had the default keyword
args compiled before the default position args (even though they appear
in the other order in the text of the script), and I thought it was
important to have the same order of execution when evaluating default
arguments. CPython 3.4 has changed the order to the more obvious one,
so we can also change.
Damien George
Paul Sokolovsky
AZ Huang