Commit Graph

3861 Commits

Author SHA1 Message Date
stijn
ea880d5674 py/builtinimport: Forward all debug printing to MICROPY_DEBUG_PRINTER. 2021-09-24 13:17:19 +10:00
iabdalkader
2c5e9bbdfa extmod: Add platform module.
It contains the compiler version, and underlying system HAL/SDK version.
2021-09-19 23:35:10 +10:00
Jim Mussared
b326edf68c all: Remove MICROPY_OPT_CACHE_MAP_LOOKUP_IN_BYTECODE.
This commit removes all parts of code associated with the existing
MICROPY_OPT_CACHE_MAP_LOOKUP_IN_BYTECODE optimisation option, including the
-mcache-lookup-bc option to mpy-cross.

This feature originally provided a significant performance boost for Unix,
but wasn't able to be enabled for MCU targets (due to frozen bytecode), and
added significant extra complexity to generating and distributing .mpy
files.

The equivalent performance gain is now provided by the combination of
MICROPY_OPT_LOAD_ATTR_FAST_PATH and MICROPY_OPT_MAP_LOOKUP_CACHE (which has
been enabled on the unix port in the previous commit).

It's hard to provide precise performance numbers, but tests have been run
on a wide variety of architectures (x86-64, ARM Cortex, Aarch64, RISC-V,
xtensa) and they all generally agree on the qualitative improvements seen
by the combination of MICROPY_OPT_LOAD_ATTR_FAST_PATH and
MICROPY_OPT_MAP_LOOKUP_CACHE.

For example, on a "quiet" Linux x64 environment (i3-5010U @ 2.10GHz) the
change from CACHE_MAP_LOOKUP_IN_BYTECODE, to LOAD_ATTR_FAST_PATH combined
with MAP_LOOKUP_CACHE is:

diff of scores (higher is better)
N=2000 M=2000       bccache -> attrmapcache      diff      diff% (error%)
bm_chaos.py        13742.56 ->   13905.67 :   +163.11 =  +1.187% (+/-3.75%)
bm_fannkuch.py        60.13 ->      61.34 :     +1.21 =  +2.012% (+/-2.11%)
bm_fft.py         113083.20 ->  114793.68 :  +1710.48 =  +1.513% (+/-1.57%)
bm_float.py       256552.80 ->  243908.29 : -12644.51 =  -4.929% (+/-1.90%)
bm_hexiom.py         521.93 ->     625.41 :   +103.48 = +19.826% (+/-0.40%)
bm_nqueens.py     197544.25 ->  217713.12 : +20168.87 = +10.210% (+/-3.01%)
bm_pidigits.py      8072.98 ->    8198.75 :   +125.77 =  +1.558% (+/-3.22%)
misc_aes.py        17283.45 ->   16480.52 :   -802.93 =  -4.646% (+/-0.82%)
misc_mandel.py     99083.99 ->  128939.84 : +29855.85 = +30.132% (+/-5.88%)
misc_pystone.py    83860.10 ->   82592.56 :  -1267.54 =  -1.511% (+/-2.27%)
misc_raytrace.py   21490.40 ->   22227.23 :   +736.83 =  +3.429% (+/-1.88%)

This shows that the new optimisations are at least as good as the existing
inline-bytecode-caching, and are sometimes much better (because the new
ones apply caching to a wider variety of map lookups).

The new optimisations can also benefit code generated by the native
emitter, because they apply to the runtime rather than the generated code.
The improvement for the native emitter when LOAD_ATTR_FAST_PATH and
MAP_LOOKUP_CACHE are enabled is (same Linux environment as above):

diff of scores (higher is better)
N=2000 M=2000        native -> nat-attrmapcache  diff      diff% (error%)
bm_chaos.py        14130.62 ->   15464.68 :  +1334.06 =  +9.441% (+/-7.11%)
bm_fannkuch.py        74.96 ->      76.16 :     +1.20 =  +1.601% (+/-1.80%)
bm_fft.py         166682.99 ->  168221.86 :  +1538.87 =  +0.923% (+/-4.20%)
bm_float.py       233415.23 ->  265524.90 : +32109.67 = +13.756% (+/-2.57%)
bm_hexiom.py         628.59 ->     734.17 :   +105.58 = +16.796% (+/-1.39%)
bm_nqueens.py     225418.44 ->  232926.45 :  +7508.01 =  +3.331% (+/-3.10%)
bm_pidigits.py      6322.00 ->    6379.52 :    +57.52 =  +0.910% (+/-5.62%)
misc_aes.py        20670.10 ->   27223.18 :  +6553.08 = +31.703% (+/-1.56%)
misc_mandel.py    138221.11 ->  152014.01 : +13792.90 =  +9.979% (+/-2.46%)
misc_pystone.py    85032.14 ->  105681.44 : +20649.30 = +24.284% (+/-2.25%)
misc_raytrace.py   19800.01 ->   23350.73 :  +3550.72 = +17.933% (+/-2.79%)

In summary, compared to MICROPY_OPT_CACHE_MAP_LOOKUP_IN_BYTECODE, the new
MICROPY_OPT_LOAD_ATTR_FAST_PATH and MICROPY_OPT_MAP_LOOKUP_CACHE options:
- are simpler;
- take less code size;
- are faster (generally);
- work with code generated by the native emitter;
- can be used on embedded targets with a small and constant RAM overhead;
- allow the same .mpy bytecode to run on all targets.

See #7680 for further discussion.  And see also #7653 for a discussion
about simplifying mpy-cross options.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
2021-09-16 16:04:03 +10:00
Jim Mussared
11ef8f22fe py/map: Add an optional cache of (map+index) to speed up map lookups.
The existing inline bytecode caching optimisation, selected by
MICROPY_OPT_CACHE_MAP_LOOKUP_IN_BYTECODE, reserves an extra byte in the
bytecode after certain opcodes, which at runtime stores a map index of the
likely location of this field when looking up the qstr.  This scheme is
incompatible with bytecode-in-ROM, and doesn't work with native generated
code.  It also stores bytecode in .mpy files which is of a different format
to when the feature is disabled, making generation of .mpy files more
complex.

This commit provides an alternative optimisation via an approach that adds
a global cache for map offsets, then all mp_map_lookup operations use it.
It's less precise than bytecode caching, but allows the cache to be
independent and external to the bytecode that is executing.  It also works
for the native emitter and adds a similar performance boost on top of the
gain already provided by the native emitter.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
2021-09-16 16:02:19 +10:00
Jim Mussared
7b89ad8dbf py/vm: Add a fast path for LOAD_ATTR on instance types.
When the LOAD_ATTR opcode is executed there are quite a few different cases
that have to be handled, but the common case is accessing a member on an
instance type.  Typically, built-in types provide methods which is why this
is common.

Fortunately, for this specific case, if the member is found in the member
map then there's no further processing.

This optimisation does a relatively cheap check (type is instance) and then
forwards directly to the member map lookup, falling back to the regular
path if necessary.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
2021-09-16 16:02:15 +10:00
Jim Mussared
01374d941f py/mpconfig.h: Define initial templates for "feature levels".
This is the beginning of a set of changes to simplify enabling/disabling
features.  The goals are:
- Remove redundancy from mpconfigport.h (never set a value to the default
  -- make it clear exactly what's being enabled).
- Improve consistency between ports.  All "similar" ports (i.e. approx same
  flash size) should get the same features.
- Simplify mpconfigport.h -- just get default/sensible options for the size
  of the port.
- Make it easy for defining constrained boards (e.g. STM32F0/L0), they can
  just set a lower level.

This commit makes a step towards this and defines the "core" level as the
current default feature set, and a "minimal" level to turn off everything.
And a few placeholder levels are added for where the other ports will
roughly land.

This is a no-op change for all ports.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
2021-09-16 13:19:11 +10:00
Damien George
426785a19e py/emitnative: Ensure load_subscr does not clobber existing REG_RET.
Fixes issue #7782, and part of issue #6314.

Signed-off-by: Damien George <damien@micropython.org>
2021-09-13 22:30:24 +10:00
Damien George
e6850838cd py/parse: Simplify parse nodes representing a list.
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>
2021-09-10 14:09:44 +10:00
Damien George
af64c2ddbd extmod/machine_pwm: Factor out machine.PWM bindings to common code.
This commit refactors machine.PWM and creates extmod/machine_pwm.c.  The
esp8266, esp32 and rp2 ports all use this and provide implementations of
the required PWM functionality.  This helps to reduce code duplication and
keep the same Python API across ports.

This commit does not make any functional changes.

Signed-off-by: Damien George <damien@micropython.org>
2021-09-04 16:31:17 +10:00
Damien George
d41f6dde56 extmod/modonewire: Make _onewire module configurable via macro option.
Signed-off-by: Damien George <damien@micropython.org>
2021-09-02 13:11:23 +10:00
Damien George
afe0634c98 extmod/machine_spi: Make SoftSPI configurable via macro option.
Signed-off-by: Damien George <damien@micropython.org>
2021-09-02 13:11:23 +10:00
Damien George
122d901ef1 extmod/machine_i2c: Make SoftI2C configurable via macro option.
The zephyr port doesn't support SoftI2C so it's not enabled, and the legacy
I2C constructor check can be removed.

Signed-off-by: Damien George <damien@micropython.org>
2021-09-02 13:11:23 +10:00
Damien George
7c54b64280 all: Bump version to 1.17.
Signed-off-by: Damien George <damien@micropython.org>
2021-09-02 00:07:13 +10:00
Jim Mussared
b51e7e9d01 stm32: Disable computed goto on constrained boards.
Saves ~1kiB.  Add comment to this effect to mpconfig.h.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
2021-08-20 20:18:52 +10:00
Jim Mussared
85adc25558 py/mkrules.mk: Do submodule sync in "make submodules".
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
2021-08-19 22:53:44 +10:00
Jim Mussared
e64cda5295 stm32: Add implementation of machine.bitstream.
Hand-written version for M0, and cycle-counter version for everything else.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
2021-08-19 22:50:32 +10:00
Jim Mussared
870000f35b extmod: Add machine.bitstream.
This is a generic API for synchronously bit-banging data on a pin.

Initially this adds a single supported encoding, which supports controlling
WS2812 LEDs.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
2021-08-19 22:50:11 +10:00
Jim Mussared
5555f147df py/lexer: Clear fstring_args vstr on lexer free.
This was missed in 692d36d779.  It's not
strictly necessary as the GC will clean it anyway, but it's good to
pre-emptively gc_free() all the blocks used in lexing/parsing.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
2021-08-19 17:31:02 +10:00
Jim Mussared
692d36d779 py: Implement partial PEP-498 (f-string) support.
This implements (most of) the PEP-498 spec for f-strings and is based on
https://github.com/micropython/micropython/pull/4998 by @klardotsh.

It is implemented in the lexer as a syntax translation to `str.format`:
  f"{a}" --> "{}".format(a)

It also supports:
  f"{a=}" --> "a={}".format(a)

This is done by extracting the arguments into a temporary vstr buffer,
then after the string has been tokenized, the lexer input queue is saved
and the contents of the temporary vstr buffer are injected into the lexer
instead.

There are four main limitations:
- raw f-strings (`fr` or `rf` prefixes) are not supported and will raise
  `SyntaxError: raw f-strings are not supported`.

- literal concatenation of f-strings with adjacent strings will fail
    "{}" f"{a}" --> "{}{}".format(a)    (str.format will incorrectly use
                                         the braces from the non-f-string)
    f"{a}" f"{a}" --> "{}".format(a) "{}".format(a) (cannot concatenate)

- PEP-498 requires the full parser to understand the interpolated
  argument, however because this entirely runs in the lexer it cannot
  resolve nested braces in expressions like
    f"{'}'}"

- The !r, !s, and !a conversions are not supported.

Includes tests and cpydiffs.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
2021-08-14 16:58:40 +10:00
Damien George
78718fffb1 py/mkrules: Automatically build mpy-cross if it doesn't exist.
Commit 4173950658 removed automatic building
of mpy-cross, which rebuilt it whenever any of its dependent source files
changed.

But needing to build mpy-cross, and not knowing how, is a frequent issue.
This commit aims to help by automatically building mpy-cross only if it
doesn't exist.  For Makefiles it uses an order-only prerequisite, while
for CMake it uses a custom command.

If MICROPY_MPYCROSS (which is what makemanifest.py uses to locate the
mpy-cross executable) is defined in the environment then automatic build
will not be attempted, allowing a way to prevent this auto-build if needed.

Thanks to Trammell Hudson aka @osresearch for the original idea; see #5760.

Signed-off-by: Damien George <damien@micropython.org>
2021-08-07 20:25:32 +10:00
Peter Züger
ffc854f17f extmod/modujson: Add support for dump/dumps separators keyword-argument.
Optionally enabled via MICROPY_PY_UJSON_SEPARATORS.  Enabled by default.

For dump, make sure mp_get_stream_raise is called after
mod_ujson_separators since CPython does it in this order (if both
separators and stream are invalid, separators will raise an exception
first).

Add separators argument in the docs as well.

Signed-off-by: Peter Züger <zueger.peter@icloud.com>
Signed-off-by: Damien George <damien@micropython.org>
2021-08-07 13:52:16 +10:00
David Lechner
afcc77cebc py/builtinimport: Fix condition for including do_execute_raw_code().
Commit e33bc597 ("py: Remove calls to file reader functions when these
are disabled.") changed the condition for one caller of
do_execute_raw_code() from

    MICROPY_PERSISTENT_CODE_LOAD

to

    MICROPY_HAS_FILE_READER && MICROPY_PERSISTENT_CODE_LOAD

The condition that enables compiling the function itself needs to be
changed to match.

Signed-off-by: David Lechner <david@pybricks.com>
2021-07-31 16:51:58 +10:00
Jim Mussared
4e39ff221a py/runtime: Fix bool unary op for subclasses of native types.
Previously a subclass of a type that didn't implement unary_op, or didn't
handle MP_UNARY_OP_BOOL, would raise TypeError on bool conversion.

Fixes #5677.
2021-07-23 12:40:00 +10:00
Jim Mussared
0e3752e82a py/emitnative: Ensure stack settling is safe mid-branch.
And add a test for the case where REG_RET could be in use.

Fixes #7523.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
2021-07-19 23:18:59 +10:00
Damien George
d0227d5862 py/emitnative: Reuse need_reg_all func in need_stack_settled.
To reduce code size and code duplication.

Signed-off-by: Damien George <damien@micropython.org>
2021-07-19 23:18:13 +10:00
David Lechner
8758504f0f extmod/moduselect: Conditionally compile select().
This adds #if MICROPY_PY_USELECT_SELECT around the uselect.select()
function. According to the docs, this function is only for CPython
compatibility and should not normally be used. So we can disable it
and save a few bytes of flash space where possible.

Signed-off-by: David Lechner <david@pybricks.com>
2021-07-17 23:32:39 +10:00
Damien George
70b8e1d1f5 py/obj: Fix formatting of comment for mp_obj_is_integer.
Signed-off-by: Damien George <damien@micropython.org>
2021-07-15 00:12:41 +10:00
Damien George
022b8a7fea py/objexcept: Make mp_obj_new_exception_arg1 inline.
This function is rarely used so making it inline reduces code size.

Signed-off-by: Damien George <damien@micropython.org>
2021-07-15 00:12:41 +10:00
Damien George
74085f167e py/modsys: Optimise sys.exit for code size by using exception helpers.
Signed-off-by: Damien George <damien@micropython.org>
2021-07-15 00:12:41 +10:00
Damien George
38a204ed96 py: Introduce and use mp_raise_type_arg helper.
To reduce code size.

Signed-off-by: Damien George <damien@micropython.org>
2021-07-15 00:12:41 +10:00
Damien George
bb00125aaa py: Support single argument to optimised MP_OBJ_STOP_ITERATION.
The MP_OBJ_STOP_ITERATION optimisation is a shortcut for creating a
StopIteration() exception object, and means that heap memory does not need
to be allocated for the exception (in cases where it can be used).  This
commit allows this optimised object to take an optional argument (before,
it could only have no argument).

The commit also adds some new tests to cover corner cases with
StopIteration and generators that previously did not work.

Signed-off-by: Damien George <damien@micropython.org>
2021-07-15 00:12:41 +10:00
Damien George
e3825e28e6 py/objexcept: Make mp_obj_exception_get_value support subclassed excs.
Signed-off-by: Damien George <damien@micropython.org>
2021-07-15 00:12:41 +10:00
Damien George
b8255dd2e0 py/vm: Simplify handling of MP_OBJ_STOP_ITERATION in yield-from opcode.
Signed-off-by: Damien George <damien@micropython.org>
2021-07-15 00:12:41 +10:00
Damien George
136369d72f all: Update to point to files in new shared/ directory.
Signed-off-by: Damien George <damien@micropython.org>
2021-07-12 17:08:10 +10:00
Bryan Tong Minh
3d9af87721 windows/Makefile: Add .exe extension to executables name.
Uses the same logic applied in 5b57ae985f
to determine when to add .exe.

See related: #3310, #3361, #3370, #4143, #5727.
2021-07-08 12:35:08 +10:00
David Lechner
d934f8c8a8 py/makeversionhdr: Add --tags arg to git describe.
This adds the --tags argument to the git describe command that is used
to define the MICROPY_GIT_TAG macro. This makes it match non-annotated
tags. This is useful for MicroPython derivatives that don't use
annotated tags.

Signed-off-by: David Lechner <david@pybricks.com>
2021-07-05 10:41:31 -05:00
David Lechner
58e4d72338 py/objexcept: Pretty print OSError also when it has 2 arguments.
This extends pretty-printing of OSError's to handle two arguments when the
exception name is known.

Signed-off-by: David Lechner <david@pybricks.com>
2021-07-01 13:23:54 +10:00
Yonatan Goldschmidt
4ada56d4cb tools/makemanifest.py: Allow passing flags to mpy-tool.py. 2021-06-28 01:50:00 +03:00
Damien George
cfd08448a1 py: Mark unused arguments from bytecode decoding macros.
Signed-off-by: Damien George <damien@micropython.org>
2021-06-25 10:58:22 +10:00
Damien George
08e0e065f4 py/makeqstrdefs.py: Don't include .h files explicitly in preprocessing.
Only include .c and .cpp files explicitly in the list of files passed to
the preprocessor for QSTR extraction.  All relevant .h files will be
included in this process by "#include" from the .c(pp) files.  In
particular for moduledefs.h, this is included by py/objmodule.c (and
doesn't actually contain any extractable MP_QSTR_xxx, but rather defines
macros with MP_QSTR_xxx's in them which are then part of py/objmodule.c).

The main reason for this change is to simplify the preprocessing step on
the javascript port, which tries to compile .h files as C++ precompiled
headers if they are passed with -E to clang.

Signed-off-by: Damien George <damien@micropython.org>
2021-06-25 10:50:54 +10:00
David Lechner
b51ae20c07 py/mperrno: Add MP_ECANCELED error code.
This is useful when binding asynchronous functions in C.

Signed-off-by: David Lechner <david@pybricks.com>
2021-06-24 23:14:01 +10:00
Jeff Epler
413f34cd8f all: Fix signed shifts and NULL access errors from -fsanitize=undefined.
Fixes the following (the line numbers match commit 0e87459e2b):

../../extmod/crypto-algorithms/sha256.c:49:19: runtime error: left shif...
../../extmod/moduasyncio.c:106:35: runtime error: member access within ...
../../py/binary.c:210:13: runtime error: left shift of negative value -...
../../py/mpz.c:744:16: runtime error: negation of -9223372036854775808 ...
../../py/objint.c:109:22: runtime error: left shift of 1 by 31 places c...
../../py/objint_mpz.c:374:9: runtime error: left shift of 4611686018427...
../../py/objint_mpz.c:374:9: runtime error: left shift of negative valu...
../../py/parsenum.c:106:14: runtime error: left shift of 46116860184273...
../../py/runtime.c:395:33: runtime error: left shift of negative value ...
../../py/showbc.c:177:28: runtime error: left shift of negative value -...
../../py/vm.c:321:36: runtime error: left shift of negative value -1```

Testing was done on an amd64 Debian Buster system using gcc-8.3 and these
settings:

    CFLAGS += -g3 -Og -fsanitize=undefined
    LDFLAGS += -fsanitize=undefined

The introduced TASK_PAIRHEAP macro's conditional (x ? &x->i : NULL)
assembles (under amd64 gcc 8.3 -Os) to the same as &x->i, since i is the
initial field of the struct.  However, for the purposes of undefined
behavior analysis the conditional is needed.

Signed-off-by: Jeff Epler <jepler@gmail.com>
2021-06-24 23:01:04 +10:00
David Lechner
259d9b69fe py/mpstate: Schedule KeyboardInterrupt on main thread.
This introduces a new macro to get the main thread and uses it to ensure
that asynchronous exceptions such as KeyboardInterrupt (CTRL+C) are only
scheduled on the main thread. This is more deterministic than being
scheduled on a random thread and is more in line with CPython that only
allow signal handlers to run on the main thread.

Fixes issue #7026.

Signed-off-by: David Lechner <david@pybricks.com>
2021-06-19 09:49:00 +10:00
David Lechner
ca920f7218 py/mpstate: Make exceptions thread-local.
This moves mp_pending_exception from mp_state_vm_t to mp_state_thread_t.
This allows exceptions to be scheduled on a specific thread.

Signed-off-by: David Lechner <david@pybricks.com>
2021-06-19 09:43:44 +10:00
Damien George
7c51cb2307 all: Bump version to 1.16.
Signed-off-by: Damien George <damien@micropython.org>
2021-06-18 16:38:06 +10:00
Damien George
bc89cdeb45 py/gc: Only use no_sanitize_address attribute for GCC 4.8 and above.
It's not supported on older GCC versions.

Signed-off-by: Damien George <damien@micropython.org>
2021-06-18 14:15:37 +10:00
Damien George
5e1d3c8b5d py/stackctrl: Prevent unused-var warning when stack checking disabled.
Signed-off-by: Damien George <damien@micropython.org>
2021-06-05 11:03:09 +10:00
Damien George
a70a4e6688 py/emitglue: Always flush caches when assigning native ARM code.
Prior to this commit, cache flushing for ARM native code was done only in
the assembler code asm_thumb_end_pass()/asm_arm_end_pass(), at the last
pass of the assembler.  But this misses flushing the cache when loading
native code from an .mpy file, ie in persistentcode.c.

The change here makes sure the cache is always flushed/cleaned/invalidated
when assigning native code on ARM architectures.

This problem was found running tests/micropython/import_mpy_native_gc.py on
the mimxrt port.

Signed-off-by: Damien George <damien@micropython.org>
2021-06-05 11:03:04 +10:00
Damien George
53519e322a py/builtinimport: Change relative import's ValueError to ImportError.
Following CPython change, see https://bugs.python.org/issue37444.

Signed-off-by: Damien George <damien@micropython.org>
2021-05-30 19:35:03 +10:00
Jeff Epler
d67f4115b4 py/repl: Don't read past the end of import_str.
asan considers that memcmp(p, q, N) is permitted to access N bytes at each
of p and q, even for values of p and q that have a difference earlier.
Accessing additional values is frequently done in practice, reading 4 or
more bytes from each input at a time for efficiency, so when completing
"non_exist<TAB>" in the repl, this causes a diagnostic:

    ==16938==ERROR: AddressSanitizer: global-buffer-overflow on
    address 0x555555cd8dc8 at pc 0x7ffff726457b bp 0x7fffffffda20 sp 0x7fff
    READ of size 9 at 0x555555cd8dc8 thread T0
        #0 0x7ffff726457a  (/usr/lib/x86_64-linux-gnu/libasan.so.5+0xb857a)
        #1 0x555555b0e82a in mp_repl_autocomplete ../../py/repl.c:301
        #2 0x555555c89585 in readline_process_char ../../lib/mp-readline/re
        #3 0x555555c8ac6e in readline ../../lib/mp-readline/readline.c:513
        #4 0x555555b8dcbd in do_repl /home/jepler/src/micropython/ports/uni
        #5 0x555555b90859 in main_ /home/jepler/src/micropython/ports/unix/
        #6 0x555555b90a3a in main /home/jepler/src/micropython/ports/unix/m
        #7 0x7ffff619a09a in __libc_start_main ../csu/libc-start.c:308
        #8 0x55555595fd69 in _start (/home/jepler/src/micropython/ports/uni

    0x555555cd8dc8 is located 0 bytes to the right of global variable
    'import_str' defined in '../../py/repl.c:285:23' (0x555555cd8dc0) of
    size 8
      'import_str' is ascii string 'import '

Signed-off-by: Jeff Epler <jepler@gmail.com>
2021-05-30 11:50:51 +10:00