Messages in this thread | | | From | Sedat Dilek <> | Date | Mon, 4 Jun 2018 10:12:41 +0200 | Subject | [2/3] x86/build: use -std=gnu89 for proper extern inline semantics |
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[ CC me I'am not subscribed to LKML and linux-kbuild ] [ Unsure if this the complete CC list of the original posting [0] ]
Hi,
I am discovering clang's compiler flags as HPA writes in [0]...
"-fgnu-inlines would be a better option.
We could also simply #define inline inline __attribute__((gnu_inline))"
[1] says on clang-7 compiler-flags...
Generate output compatible with the standard GNU Objective-C runtime
-fgnu89-inline, -fno-gnu89-inline
...and...
Place each function in its own section (ELF Only)
-fgnu-inline-asm, -fno-gnu-inline-asm
Should that be '-fgnu89-inline'? You happen to know what '-fgnu-inline-asm' does and it is an option?
This what Linux v4.17 says about inline defines...
[ include/linux/compiler-gcc.h ] ... /* * Force always-inline if the user requests it so via the .config, * or if gcc is too old. * GCC does not warn about unused static inline functions for * -Wunused-function. This turns out to avoid the need for complex #ifdef * directives. Suppress the warning in clang as well by using "unused" * function attribute, which is redundant but not harmful for gcc. */ #if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \ !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4) #define inline inline __attribute__((always_inline,unused)) notrace #define __inline__ __inline__ __attribute__((always_inline,unused)) notrace #define __inline __inline __attribute__((always_inline,unused)) notrace #else /* A lot of inline functions can cause havoc with function tracing */ #define inline inline __attribute__((unused)) notrace #define __inline__ __inline__ __attribute__((unused)) notrace #define __inline __inline __attribute__((unused)) notrace #endif ...
[ include/linux/compiler_types.h ] ... /* * Allow us to avoid 'defined but not used' warnings on functions and data, * as well as force them to be emitted to the assembly file. * * As of gcc 3.4, static functions that are not marked with attribute((used)) * may be elided from the assembly file. As of gcc 3.4, static data not so * marked will not be elided, but this may change in a future gcc version. * * NOTE: Because distributions shipped with a backported unit-at-a-time * compiler in gcc 3.3, we must define __used to be __attribute__((used)) * for gcc >=3.3 instead of 3.4. * * In prior versions of gcc, such functions and data would be emitted, but * would be warned about except with attribute((unused)). * * Mark functions that are referenced only in inline assembly as __used so * the code is emitted even though it appears to be unreferenced. */ #ifndef __used # define __used /* unimplemented */ #endif
#ifndef __maybe_unused # define __maybe_unused /* unimplemented */ #endif
#ifndef __always_unused # define __always_unused /* unimplemented */ #endif
#ifndef noinline #define noinline #endif
/* * Rather then using noinline to prevent stack consumption, use * noinline_for_stack instead. For documentation reasons. */ #define noinline_for_stack noinline
#ifndef __always_inline #define __always_inline inline #endif ...
Regards, - Sedat -
[0] https://patchwork.kernel.org/patch/10444075/ [1] https://clang.llvm.org/docs/ClangCommandLineReference.html
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