The recent rework of bytecode made all constants global with respect to the
module (previously, each function had its own constant table). That means
the constant table for a module is shared among all functions/methods/etc
within the module.
This commit add support to the compiler to de-duplicate constants in this
module constant table. So if a constant is used more than once -- eg 1.0
or (None, None) -- then the same object is reused for all instances.
For example, if there is code like `print(1.0, 1.0)` then the parser will
create two independent constants 1.0 and 1.0. The compiler will then (with
this commit) notice they are the same and only put one of them in the
constant table. The bytecode will then reuse that constant twice in the
print expression. That allows the second 1.0 to be reclaimed by the GC,
also means the constant table has one less entry so saves a word.
Signed-off-by: Damien George <damien@micropython.org>
Prior to this commit, all qstrs were required to be allocated (by calling
mp_emit_common_use_qstr) in the MP_PASS_SCOPE pass (the first one). But
this is an unnecessary restriction, which is lifted by this commit.
Lifting the restriction simplifies the compiler because it can allocate
qstrs in later passes.
This also generates better code, because in some cases (eg when a variable
is closed over) the scope of an identifier is not known until a bit later
and then the identifier no longer needs its qstr allocated in the global
table.
Code size is reduced for all ports with this commit.
Signed-off-by: Damien George <damien@micropython.org>
Some architectures (like esp32 xtensa) cannot read byte-wise from
executable memory. This means the prelude for native functions -- which is
usually located after the machine code for the native function -- must be
placed in separate memory that can be read byte-wise. Prior to this commit
this was achieved by enabling N_PRELUDE_AS_BYTES_OBJ for the emitter and
MICROPY_EMIT_NATIVE_PRELUDE_AS_BYTES_OBJ for the runtime. The prelude was
then placed in a bytes object, pointed to by the module's constant table.
This behaviour is changed by this commit so that a pointer to the prelude
is stored either in mp_obj_fun_bc_t.child_table, or in
mp_obj_fun_bc_t.child_table[num_children] if num_children > 0. The reasons
for doing this are:
1. It decouples the native emitter from runtime requirements, the emitted
code no longer needs to know if the system it runs on can/can't read
byte-wise from executable memory.
2. It makes all ports have the same emitter behaviour, there is no longer
the N_PRELUDE_AS_BYTES_OBJ option.
3. The module's constant table is now used only for actual constants in the
Python code. This allows further optimisations to be done with the
constants (eg constant deduplication).
Code size change for those ports that enable the native emitter:
unix x64: +80 +0.015%
stm32: +24 +0.004% PYBV10
esp8266: +88 +0.013% GENERIC
esp32: -20 -0.002% GENERIC[incl -112(data)]
rp2: +32 +0.005% PICO
Signed-off-by: Damien George <damien@micropython.org>
There were two issues with the existing code:
1. "1 << i" is computed as a 32-bit number so would overflow when
executed on 64-bit machines (when mp_uint_t is 64-bit). This meant that
*args beyond 32 positions would not be handled correctly.
2. star_args must fit as a positive small int so that it is encoded
correctly in the emitted code. MP_SMALL_INT_BITS is too big because it
overflows a small int by 1 bit. MP_SMALL_INT_BITS - 1 does not work
because it produces a signed small int which is then sign extended when
extracted (even by mp_obj_get_int_truncated), and this sign extension
means that any position arg after *args is also treated as a star-arg.
So the maximum bit position is MP_SMALL_INT_BITS - 2. This means that
MP_OBJ_SMALL_INT_VALUE() can be used instead of
mp_obj_get_int_truncated() to get the value of star_args.
These issues are fixed by this commit, and a test added.
Signed-off-by: Damien George <damien@micropython.org>
This is a partial implementation of PEP 448 to allow unpacking multiple
star args in a function or method call.
This is implemented by changing the emitted bytecodes so that both
positional args and star args are stored as positional args. A bitmap is
added to indicate if an argument at a given position is a positional
argument or a star arg.
In the generated code, this new bitmap takes the place of the old star arg.
It is stored as a small int, so this means only the first N arguments can
be star args where N is the number of bits in a small int.
The runtime is modified to interpret this new bytecode format while still
trying to perform as few memory reallocations as possible.
Signed-off-by: David Lechner <david@pybricks.com>
This is a partial implementation of PEP 448 to allow multiple ** unpackings
when calling a function or method.
The compiler is modified to encode the argument as a None: obj key-value
pair (similar to how regular keyword arguments are encoded as str: obj
pairs). The extra object that was pushed on the stack to hold a single **
unpacking object is no longer used and is removed.
The runtime is modified to decode this new format.
Signed-off-by: David Lechner <david@pybricks.com>
This commit introduces changes:
- All jump opcodes are changed to have variable length arguments, of either
1 or 2 bytes (previously they were fixed at 2 bytes). In most cases only
1 byte is needed to encode the short jump offset, saving bytecode size.
- The bytecode emitter now selects 1 byte jump arguments when the jump
offset is guaranteed to fit in 1 byte. This is achieved by checking if
the code size changed during the last pass and, if it did (if it shrank),
then requesting that the compiler make another pass to get the correct
offsets of the now-smaller code. This can continue multiple times until
the code stabilises. The code can only ever shrink so this iteration is
guaranteed to complete. In most cases no extra passes are needed, the
original 4 passes are enough to get it right by the 4th pass (because the
2nd pass computes roughly the correct labels and the 3rd pass computes
the correct size for the jump argument).
This change to the jump opcode encoding reduces .mpy files and RAM usage
(when bytecode is in RAM) by about 2% on average.
The performance of the VM is not impacted, at least within measurment of
the performance benchmark suite.
Code size is reduced for builds that include a decent amount of frozen
bytecode. ARM Cortex-M builds without any frozen code increase by about
350 bytes.
Signed-off-by: Damien George <damien@micropython.org>
The bytecode state variables mp_showbc_code_start and mp_showbc_constants
have been removed and made local variables passed into the various
functions.
As part of this, the DECODE_PTR macro is fixed so it extracts the relevant
pointer from the child_table (a regression introduced in
f2040bfc7e).
Signed-off-by: Damien George <damien@micropython.org>
This means that all constants for EMIT_ARG(load_const_obj, obj) are created
in the parser (rather than some in the compiler).
Signed-off-by: Damien George <damien@micropython.org>
Background: .mpy files are precompiled .py files, built using mpy-cross,
that contain compiled bytecode functions (and can also contain machine
code). The benefit of using an .mpy file over a .py file is that they are
faster to import and take less memory when importing. They are also
smaller on disk.
But the real benefit of .mpy files comes when they are frozen into the
firmware. This is done by loading the .mpy file during compilation of the
firmware and turning it into a set of big C data structures (the job of
mpy-tool.py), which are then compiled and downloaded into the ROM of a
device. These C data structures can be executed in-place, ie directly from
ROM. This makes importing even faster because there is very little to do,
and also means such frozen modules take up much less RAM (because their
bytecode stays in ROM).
The downside of frozen code is that it requires recompiling and reflashing
the entire firmware. This can be a big barrier to entry, slows down
development time, and makes it harder to do OTA updates of frozen code
(because the whole firmware must be updated).
This commit attempts to solve this problem by providing a solution that
sits between loading .mpy files into RAM and freezing them into the
firmware. The .mpy file format has been reworked so that it consists of
data and bytecode which is mostly static and ready to run in-place. If
these new .mpy files are located in flash/ROM which is memory addressable,
the .mpy file can be executed (mostly) in-place.
With this approach there is still a small amount of unpacking and linking
of the .mpy file that needs to be done when it's imported, but it's still
much better than loading an .mpy from disk into RAM (although not as good
as freezing .mpy files into the firmware).
The main trick to make static .mpy files is to adjust the bytecode so any
qstrs that it references now go through a lookup table to convert from
local qstr number in the module to global qstr number in the firmware.
That means the bytecode does not need linking/rewriting of qstrs when it's
loaded. Instead only a small qstr table needs to be built (and put in RAM)
at import time. This means the bytecode itself is static/constant and can
be used directly if it's in addressable memory. Also the qstr string data
in the .mpy file, and some constant object data, can be used directly.
Note that the qstr table is global to the module (ie not per function).
In more detail, in the VM what used to be (schematically):
qst = DECODE_QSTR_VALUE;
is now (schematically):
idx = DECODE_QSTR_INDEX;
qst = qstr_table[idx];
That allows the bytecode to be fixed at compile time and not need
relinking/rewriting of the qstr values. Only qstr_table needs to be linked
when the .mpy is loaded.
Incidentally, this helps to reduce the size of bytecode because what used
to be 2-byte qstr values in the bytecode are now (mostly) 1-byte indices.
If the module uses the same qstr more than two times then the bytecode is
smaller than before.
The following changes are measured for this commit compared to the
previous (the baseline):
- average 7%-9% reduction in size of .mpy files
- frozen code size is reduced by about 5%-7%
- importing .py files uses about 5% less RAM in total
- importing .mpy files uses about 4% less RAM in total
- importing .py and .mpy files takes about the same time as before
The qstr indirection in the bytecode has only a small impact on VM
performance. For stm32 on PYBv1.0 the performance change of this commit
is:
diff of scores (higher is better)
N=100 M=100 baseline -> this-commit diff diff% (error%)
bm_chaos.py 371.07 -> 357.39 : -13.68 = -3.687% (+/-0.02%)
bm_fannkuch.py 78.72 -> 77.49 : -1.23 = -1.563% (+/-0.01%)
bm_fft.py 2591.73 -> 2539.28 : -52.45 = -2.024% (+/-0.00%)
bm_float.py 6034.93 -> 5908.30 : -126.63 = -2.098% (+/-0.01%)
bm_hexiom.py 48.96 -> 47.93 : -1.03 = -2.104% (+/-0.00%)
bm_nqueens.py 4510.63 -> 4459.94 : -50.69 = -1.124% (+/-0.00%)
bm_pidigits.py 650.28 -> 644.96 : -5.32 = -0.818% (+/-0.23%)
core_import_mpy_multi.py 564.77 -> 581.49 : +16.72 = +2.960% (+/-0.01%)
core_import_mpy_single.py 68.67 -> 67.16 : -1.51 = -2.199% (+/-0.01%)
core_qstr.py 64.16 -> 64.12 : -0.04 = -0.062% (+/-0.00%)
core_yield_from.py 362.58 -> 354.50 : -8.08 = -2.228% (+/-0.00%)
misc_aes.py 429.69 -> 405.59 : -24.10 = -5.609% (+/-0.01%)
misc_mandel.py 3485.13 -> 3416.51 : -68.62 = -1.969% (+/-0.00%)
misc_pystone.py 2496.53 -> 2405.56 : -90.97 = -3.644% (+/-0.01%)
misc_raytrace.py 381.47 -> 374.01 : -7.46 = -1.956% (+/-0.01%)
viper_call0.py 576.73 -> 572.49 : -4.24 = -0.735% (+/-0.04%)
viper_call1a.py 550.37 -> 546.21 : -4.16 = -0.756% (+/-0.09%)
viper_call1b.py 438.23 -> 435.68 : -2.55 = -0.582% (+/-0.06%)
viper_call1c.py 442.84 -> 440.04 : -2.80 = -0.632% (+/-0.08%)
viper_call2a.py 536.31 -> 532.35 : -3.96 = -0.738% (+/-0.06%)
viper_call2b.py 382.34 -> 377.07 : -5.27 = -1.378% (+/-0.03%)
And for unix on x64:
diff of scores (higher is better)
N=2000 M=2000 baseline -> this-commit diff diff% (error%)
bm_chaos.py 13594.20 -> 13073.84 : -520.36 = -3.828% (+/-5.44%)
bm_fannkuch.py 60.63 -> 59.58 : -1.05 = -1.732% (+/-3.01%)
bm_fft.py 112009.15 -> 111603.32 : -405.83 = -0.362% (+/-4.03%)
bm_float.py 246202.55 -> 247923.81 : +1721.26 = +0.699% (+/-2.79%)
bm_hexiom.py 615.65 -> 617.21 : +1.56 = +0.253% (+/-1.64%)
bm_nqueens.py 215807.95 -> 215600.96 : -206.99 = -0.096% (+/-3.52%)
bm_pidigits.py 8246.74 -> 8422.82 : +176.08 = +2.135% (+/-3.64%)
misc_aes.py 16133.00 -> 16452.74 : +319.74 = +1.982% (+/-1.50%)
misc_mandel.py 128146.69 -> 130796.43 : +2649.74 = +2.068% (+/-3.18%)
misc_pystone.py 83811.49 -> 83124.85 : -686.64 = -0.819% (+/-1.03%)
misc_raytrace.py 21688.02 -> 21385.10 : -302.92 = -1.397% (+/-3.20%)
The code size change is (firmware with a lot of frozen code benefits the
most):
bare-arm: +396 +0.697%
minimal x86: +1595 +0.979% [incl +32(data)]
unix x64: +2408 +0.470% [incl +800(data)]
unix nanbox: +1396 +0.309% [incl -96(data)]
stm32: -1256 -0.318% PYBV10
cc3200: +288 +0.157%
esp8266: -260 -0.037% GENERIC
esp32: -216 -0.014% GENERIC[incl -1072(data)]
nrf: +116 +0.067% pca10040
rp2: -664 -0.135% PICO
samd: +844 +0.607% ADAFRUIT_ITSYBITSY_M4_EXPRESS
As part of this change the .mpy file format version is bumped to version 6.
And mpy-tool.py has been improved to provide a good visualisation of the
contents of .mpy files.
In summary: this commit changes the bytecode to use qstr indirection, and
reworks the .mpy file format to be simpler and allow .mpy files to be
executed in-place. Performance is not impacted too much. Eventually it
will be possible to store such .mpy files in a linear, read-only, memory-
mappable filesystem so they can be executed from flash/ROM. This will
essentially be able to replace frozen code for most applications.
Signed-off-by: Damien George <damien@micropython.org>
This commit simplifies and optimises the parse tree in-memory
representation of lists of expressions, for tuples and lists, and when
tuples are used on the left-hand-side of assignments and within del
statements. This reduces memory usage of the parse tree when such code is
compiled, and also reduces the size of the compiler.
For example, (1,) was previously the following parse tree:
expr_stmt(5) (n=2)
atom_paren(45) (n=1)
testlist_comp(146) (n=2)
int(1)
testlist_comp_3b(149) (n=1)
NULL
NULL
and with this commit is now:
expr_stmt(5) (n=2)
atom_paren(45) (n=1)
testlist_comp(146) (n=1)
int(1)
NULL
Similarly, (1, 2, 3) was previously:
expr_stmt(5) (n=2)
atom_paren(45) (n=1)
testlist_comp(146) (n=2)
int(1)
testlist_comp_3c(150) (n=2)
int(2)
int(3)
NULL
and is now:
expr_stmt(5) (n=2)
atom_paren(45) (n=1)
testlist_comp(146) (n=3)
int(1)
int(2)
int(3)
NULL
Signed-off-by: Damien George <damien@micropython.org>
This introduces a new option, MICROPY_ERROR_REPORTING_NONE, which
completely disables all error messages. To be used in cases where
MicroPython needs to fit in very limited systems.
Signed-off-by: Damien George <damien@micropython.org>
MicroPython's original implementation of __aiter__ was correct for an
earlier (provisional) version of PEP492 (CPython 3.5), where __aiter__ was
an async-def function. But that changed in the final version of PEP492 (in
CPython 3.5.2) where the function was changed to a normal one. See
https://www.python.org/dev/peps/pep-0492/#why-aiter-does-not-return-an-awaitable
See also the note at the end of this subsection in the docs:
https://docs.python.org/3.5/reference/datamodel.html#asynchronous-iterators
And for completeness the BPO: https://bugs.python.org/issue27243
To be consistent with the Python spec as it stands today (and now that
PEP492 is final) this commit changes MicroPython's behaviour to match
CPython: __aiter__ should return an async-iterable object, but is not
itself awaitable.
The relevant tests are updated to match.
See #6267.
This addition to the grammar was introduced in Python 3.6. It allows
annotating the type of a varilable, like:
x: int = 123
s: str
The implementation in this commit is quite simple and just ignores the
annotation (the int and str bits above). The reason to implement this is
to allow Python 3.6+ code that uses this feature to compile under
MicroPython without change, and for users to use type checkers.
In the future viper could use this syntax as a way to give types to
variables, which is currently done in a bit of an ad-hoc way, eg
x = int(123). And this syntax could potentially be used in the inline
assembler to define labels in an way that's easier to read.
The syntax matches CPython and the semantics are equivalent except that,
unlike CPython, MicroPython allows using := to assign to comprehension
iteration variables, because disallowing this would take a lot of code to
check for it.
The new compile-time option MICROPY_PY_ASSIGN_EXPR selects this feature and
is enabled by default, following MICROPY_PY_ASYNC_AWAIT.
Note: the uncrustify configuration is explicitly set to 'add' instead of
'force' in order not to alter the comments which use extra spaces after //
as a means of indenting text for clarity.
The decompression of error-strings is only done if the string is accessed
via printing or via er.args. Tests are added for this feature to ensure
the decompression works.
Instead of compiler-level if-logic. This is necessary to know what error
strings are included in the build at the preprocessor stage, so that string
compression can be implemented.
A 'return' statement on module/class level is not correct Python, but
nothing terribly bad happens when it's allowed. So remove the check unless
MICROPY_CPYTHON_COMPAT is on.
This is similar to MicroPython's treatment of 'import *' in functions
(except 'return' has unsurprising behavior if it's allowed).
This check follows CPython's behaviour, because 'import *' always populates
the globals with the imported names, not locals.
Since it's safe to do this (doesn't lead to a crash or undefined behaviour)
the check is only enabled for MICROPY_CPYTHON_COMPAT.
Fixes issue #5121.
This commit adds support for sys.settrace, allowing to install Python
handlers to trace execution of Python code. The interface follows CPython
as closely as possible. The feature is disabled by default and can be
enabled via MICROPY_PY_SYS_SETTRACE.
Prior to this patch the line number for a lambda would be "line 1" if the
body of the lambda contained only a simple expression (with no line number
stored in the parse node). Now the line number is always reported
correctly.
mp_compile no longer takes an emit_opt argument, rather this setting is now
provided by the global default_emit_opt variable.
Now, when -X emit=native is passed as a command-line option, the emitter
will be set for all compiled modules (included imports), not just the
top-level script.
In the future there could be a way to also set this variable from a script.
Fixes issue #4267.
Prior to this commit, building the unix port with `DEBUG=1` and
`-finstrument-functions` the compilation would fail with an error like
"control reaches end of non-void function". This change fixes this by
removing the problematic "if (0)" branches. Not all branches affect
compilation, but they are all removed for consistency.
With this change, @micropython.asm_thumb functions will work on standard
ARM processors (that are in ARM state by default), in scripts and
precompiled .mpy files.
Addresses issue #4675.
This commit adds support for saving and loading .mpy files that contain
native code (native, viper and inline-asm). A lot of the ground work was
already done for this in the form of removing pointers from generated
native code. The changes here are mainly to link in qstr values to the
native code, and change the format of .mpy files to contain native code
blocks (possibly mixed with bytecode).
A top-level summary:
- @micropython.native, @micropython.viper and @micropython.asm_thumb/
asm_xtensa are now allowed in .py files when compiling to .mpy, and they
work transparently to the user.
- Entire .py files can be compiled to native via mpy-cross -X emit=native
and for the most part the generated .mpy files should work the same as
their bytecode version.
- The .mpy file format is changed to 1) specify in the header if the file
contains native code and if so the architecture (eg x86, ARMV7M, Xtensa);
2) for each function block the kind of code is specified (bytecode,
native, viper, asm).
- When native code is loaded from a .mpy file the native code must be
modified (in place) to link qstr values in, just like bytecode (see
py/persistentcode.c:arch_link_qstr() function).
In addition, this now defines a public, native ABI for dynamically loadable
native code generated by other languages, like C.
POP_BLOCK and POP_EXCEPT are now the same, and are always followed by a
JUMP. So this optimisation reduces code size, and RAM usage of bytecode by
two bytes for each try-except handler.
This patch fixes a bug in the VM when breaking within a try-finally. The
bug has to do with executing a break within the finally block of a
try-finally statement. For example:
def f():
for x in (1,):
print('a', x)
try:
raise Exception
finally:
print(1)
break
print('b', x)
f()
Currently in uPy the above code will print:
a 1
1
1
segmentation fault (core dumped) micropython
Not only is there a seg fault, but the "1" in the finally block is printed
twice. This is because when the VM executes a finally block it doesn't
really know if that block was executed due to a fall-through of the try (no
exception raised), or because an exception is active. In particular, for
nested finallys the VM has no idea which of the nested ones have active
exceptions and which are just fall-throughs. So when a break (or continue)
is executed it tries to unwind all of the finallys, when in fact only some
may be active.
It's questionable whether break (or return or continue) should be allowed
within a finally block, because they implicitly swallow any active
exception, but nevertheless it's allowed by CPython (although almost never
used in the standard library). And uPy should at least not crash in such a
case.
The solution here relies on the fact that exception and finally handlers
always appear in the bytecode after the try body.
Note: there was a similar bug with a return in a finally block, but that
was previously fixed in b735208403
This optimisation eliminates the need to create a temporary normal dict.
The optimisation is enabled via MICROPY_COMP_CONST_LITERAL which is enabled
by default (although only has an effect if OrderdDict is enabled).
Thanks to @pfalcon for the initial idea and implementation.
All exceptions that unwind through the async-with must be caught and
BaseException is the top-level class, which includes Exception and others.
Fixes issue #4552.
Damien George