On Wed, 28 Aug 2024, LIU Hao wrote:
在 2024-08-28 03:15, Pali Rohár 写道:
Use gcc's function attribute naked which omits any prologue or epilogue
sequences and for x86 is supported by gcc since version 8.0.0. It is also
supported by clang. For older gcc versions use existing code.
This change fixes compile warning:
stdio/_scprintf.c:32:20: warning: ‘init_scprintf’ used but never defined
static int __cdecl init_scprintf(const char * __restrict__ format, ...);
^~~~~~~~~~~~~
I think that introducing such complexity for just silencing a warning is an
overkill.
I somewhat agree, but I don't have a very strong opinion on it. In one
sense, we're lying to the compiler, when we claim something is a static
function, but it doesn't exist in the C source of the translation unit, so
it wouldn't surprise me if a future compiler could break this case.
If this file is only ever compiled for i686 then I would prefer the resolver
function to be implemented in assembly. The `ASM_SYM` macro is no longer
necessary.
I guess that's possible, but the more assembly code we have, the less
maintainable it is. (I'm personally not very fluent in x86 assembly,
contrary to arm/aarch64.)
A different way of getting rid of the warning, and making it safe for the
compiler, would to just make the symbol extern instead of static, and
adding e.g. a __mingw prefix to it. It's less elegant than having a static
symbol, but feels like a reasonable tradeoff between safe and maintainable
code, exposing symbols, and using fancy compiler features optionally.
(A way to make it less overkill could be to just require a compiler that
supports the attribute. But I guess there can be users who want to use the
latest mingw-w64 with old compilers too?)
// Martin
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