Re: [PATCH v2] lib/string.c: implement stpcpy

Arvind Sankar
2020-08-17T20:14:05Z

On Mon, Aug 17, 2020 at 11:36:49AM -0700, Nick Desaulniers wrote:
> > > Though I don't understand the original issue, with -ffreestanding,
> > > sprintf shouldn't have been turned into strcpy in the first place.
>
> Huh? The original issue for this thread is because `-ffreestanding`
> *isn't* being used for most targets (oh boy, actually mixed usage by
> ARCH. Looks like MIPS, m68k, superH, xtensa, and 32b x86 use it?); and
> I'm not suggesting it be used.
>

Sorry, I meant the issue mentioned in the commit that removed
-ffreestanding, not the stpcpy one you're solving now. It says that
sprintf got converted into strcpy, which caused failures because back
then, strcpy was #define'd to __builtin_strcpy, and the default
implementation was actually of a function called __builtin_strcpy o_O,
not strcpy.

Anyway, that's water under the bridge now.

6edfba1b33c7 ("x86_64: Don't define string functions to builtin")
gcc should handle this anyways, and it causes problems when
sprintf is turned into strcpy by gcc behind our backs and
the C fallback version of strcpy is actually defining __builtin_strcpy