8000 Load qstrs separately in load_raw_code_native by aykevl · Pull Request #3 · dpgeorge/micropython · GitHub
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Load qstrs separately in load_raw_code_native #3

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aykevl
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@aykevl aykevl commented Oct 19, 2017

Do not load qstrs from within the init function, but put them in a separate area of the .mpy file (with a more efficient encoding). This reduces the size of the .mpy file (94 bytes in the modx example), but increases the code size by 20 bytes on a Cortex-M0. I've also done another optimization which reduces code size by 16 bytes (net increase is thus 4 bytes).

Saves 16 bytes of code on a Cortex M0 and 7 bytes in the .mpy file.
This costs 20 bytes on a Cortex-M0 but saves 94 bytes of file size in
the modx example.
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This is superseded by micropython#5083

@dpgeorge dpgeorge closed this Oct 16, 2019
dpgeorge pushed a commit that referenced this pull request May 30, 2021
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>
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