Re: [PATCH v6 4/25] compiler-gcc{3,4}.h: Use GCC_VERSION macro

From: Andrew Morton
Date: Mon Oct 01 2012 - 15:39:51 EST


On Thu, 27 Sep 2012 20:54:20 -0500
Daniel Santos <daniel.santos@xxxxxxxxx> wrote:

> Using GCC_VERSION reduces complexity, is easier to read and is GCC's
> recommended mechanism for doing version checks. (Just don't ask me why
> they didn't define it in the first place.) This also makes it easy to
> merge compiler-gcc{3,4}.h should somebody want to.
>
> Signed-off-by: Daniel Santos <daniel.santos@xxxxxxxxx>
> ---
> include/linux/compiler-gcc3.h | 8 ++++----
> include/linux/compiler-gcc4.h | 14 +++++++-------
> 2 files changed, 11 insertions(+), 11 deletions(-)
>
> diff --git a/include/linux/compiler-gcc3.h b/include/linux/compiler-gcc3.h
> index 37d4124..7d89feb 100644
> --- a/include/linux/compiler-gcc3.h
> +++ b/include/linux/compiler-gcc3.h
> @@ -2,22 +2,22 @@
> #error "Please don't include <linux/compiler-gcc3.h> directly, include <linux/compiler.h> instead."
> #endif
>
> -#if __GNUC_MINOR__ < 2
> +#if GCC_VERSION < 30200
> # error Sorry, your compiler is too old - please upgrade it.
> #endif
>
> -#if __GNUC_MINOR__ >= 3
> +#if GCC_VERSION >= 30300
> # define __used __attribute__((__used__))
> #else
> # define __used __attribute__((__unused__))
> #endif
>
> -#if __GNUC_MINOR__ >= 4
> +#if GCC_VERSION >= 30400
> #define __must_check __attribute__((warn_unused_result))
> #endif
>
> #ifdef CONFIG_GCOV_KERNEL
> -# if __GNUC_MINOR__ < 4
> +# if GCC_VERSION < 30400
> # error "GCOV profiling support for gcc versions below 3.4 not included"
> # endif /* __GNUC_MINOR__ */
> #endif /* CONFIG_GCOV_KERNEL */
> diff --git a/include/linux/compiler-gcc4.h b/include/linux/compiler-gcc4.h
> index 4506d65..b44307d 100644
> --- a/include/linux/compiler-gcc4.h
> +++ b/include/linux/compiler-gcc4.h
> @@ -4,7 +4,7 @@
>
> /* GCC 4.1.[01] miscompiles __weak */
> #ifdef __KERNEL__
> -# if __GNUC_MINOR__ == 1 && __GNUC_PATCHLEVEL__ <= 1
> +# if GCC_VERSION >= 40100 && GCC_VERSION <= 40101
> //# error Your version of gcc miscompiles the __weak directive
> # endif
> #endif
> @@ -13,11 +13,11 @@
> #define __must_check __attribute__((warn_unused_result))
> #define __compiler_offsetof(a,b) __builtin_offsetof(a,b)
>
> -#if __GNUC_MINOR__ > 0
> +#if GCC_VERSION >= 40102

Is this correct (and clear)? I'd expect

#if GCC_VERSION > 40000

> # define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
> #endif
>
> -#if __GNUC_MINOR__ >= 3
> +#if GCC_VERSION >= 40300
> /* Mark functions as cold. gcc will assume any path leading to a call
> to them will be unlikely. This means a lot of manual unlikely()s
> are unnecessary now for any paths leading to the usual suspects
> @@ -39,9 +39,9 @@
> # define __compiletime_warning(message) __attribute__((warning(message)))
> # define __compiletime_error(message) __attribute__((error(message)))
> #endif /* __CHECKER__ */
> -#endif /* __GNUC_MINOR__ >= 3 */
> +#endif /* GCC_VERSION >= 40300 */
>
> -#if __GNUC_MINOR__ >= 5
> +#if GCC_VERSION >= 40500
> /*
> * Mark a position in code as unreachable. This can be used to
> * suppress control flow warnings after asm blocks that transfer
> @@ -56,9 +56,9 @@
> /* Mark a function definition as prohibited from being cloned. */
> #define __noclone __attribute__((__noclone__))
>
> -#endif /* __GNUC_MINOR__ >= 5 */
> +#endif /* GCC_VERSION >= 40500 */
>
> -#if __GNUC_MINOR__ >= 6
> +#if GCC_VERSION >= 40600
> /*
> * Tell the optimizer that something else uses this function or variable.
> */
> --
> 1.7.3.4
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