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Convert all nlr .S files to .c with inline asm #2923

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Merged
merged 5 commits into from
Mar 6, 2017
Merged

Convert all nlr .S files to .c with inline asm #2923

merged 5 commits into from
Mar 6, 2017

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dpgeorge
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@dpgeorge dpgeorge commented Mar 1, 2017

This PR converts all the py/nlrXXX.S assembler files to py/nlrXXX.c C files with inline assembler. The benefits of this are:

  • the core now only has .c files
  • you can #include headers in .c files to get access to config variables (before, with .S files, this was a bit of a hack)
  • no need for special treatment for linux vs mac vs windows (well, not as much as with .S files)
  • much cleaner code because now half of it is written in C
  • easily supports both threading and non-threading builds without magic numbers and difficult assembly

Drawbacks:

  • slightly less efficient due to some C overhead (a few extra instructions here and there but nothing major)

@stinos I have a feeling that this won't work properly on all windows machines / with all supported windows compilers. Can you please check and advise? Thanks.

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stinos commented Mar 1, 2017 •
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The msvc implementation uses setjmp so that is ok. With mingw the code doesn't build currently due to an undefined reference to nlr_push_tail Reason for that, as well as the solution: http://stackoverflow.com/questions/1034852/adding-leading-underscores-to-assembly-symbols-with-gcc-on-win32.
Indeed after adding this this to nlrx86.c before the definition of nlr_push

#if NLR_OS_WINDOWS
unsigned int nlr_push_tail(nlr_buf_t *nlr) asm("nlr_push_tail");
#endif

everything builds and runs. No idea why nlrx64.c doesn't seem to need this modification though.

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dpgeorge commented Mar 2, 2017

@stinos thanks for testing. I've now updated this PR to add that line in nlrx86.c and it seems that all tests are now passing.

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pfalcon commented Mar 4, 2017

ack

@dpgeorge dpgeorge merged commit 914648c into micropython:master Mar 6, 2017
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dpgeorge commented Mar 6, 2017

Ok, this is now merged.

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pfalcon commented Mar 7, 2017

So, workaround for workaround for this is pushed as fd49ff9.

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dpgeorge commented Mar 8, 2017

So, this refactor, and this particular change broke Zephyr/x86

Sorry about that! I didn't expect going from .S to .c with inline asm to be a simple change, but I still think it's worth it.

@dpgeorge dpgeorge deleted the convert-nlr-asm branch March 8, 2017 04:58
@stinos stinos mentioned this pull request Dec 18, 2017
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3 participants
@dpgeorge @stinos @pfalcon