On Tue, Jul 14, 2015 at 11:45 AM, Eric Anholt <e...@anholt.net> wrote:
> These are really useful hints to the compiler in the absence of link-time
> optimization, and I'm going to use them in VC4.
>
> I've made the const attribute be ATTRIBUTE_CONST unlike other function
> attributes, because we have other things in the tree #defining CONST for
> their own unrelated purposes.
> ---
> configure.ac | 2 ++
> src/util/macros.h | 20 ++++++++++++++++++++
> 2 files changed, 22 insertions(+)
>
> diff --git a/configure.ac b/configure.ac
> index bdfd134..38ad398 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -210,6 +210,8 @@ AX_GCC_FUNC_ATTRIBUTE([format])
> AX_GCC_FUNC_ATTRIBUTE([malloc])
> AX_GCC_FUNC_ATTRIBUTE([packed])
> AX_GCC_FUNC_ATTRIBUTE([unused])
> +AX_GCC_FUNC_ATTRIBUTE([const])
> +AX_GCC_FUNC_ATTRIBUTE([pure])
> AX_GCC_FUNC_ATTRIBUTE([warn_unused_result])
>
> AM_CONDITIONAL([GEN_ASM_OFFSETS], test "x$GEN_ASM_OFFSETS" = xyes)
> diff --git a/src/util/macros.h b/src/util/macros.h
> index 66698e7..4d16183 100644
> --- a/src/util/macros.h
> +++ b/src/util/macros.h
> @@ -130,6 +130,26 @@ do { \
> #define PACKED
> #endif
>
> +/* Attribute pure is used for functions that have no effects other than their
> + * return value. As a result, calls to it can be dead code eliminated.
> + */
> +#ifdef HAVE_FUNC_ATTRIBUTE_PURE
> +#define PURE __attribute__((__pure__))
> +#else
> +#define PURE
> +#endif
> +
> +/* Attribute const is used for functions that have no effects other than
> their
> + * return value, and only rely on the argument values to compute the return
> + * value. As a result, calls to it can be CSEed. Note that using memory
> + * pointed to by the arguments is not allowed for const functions.
> + */
> +#ifdef HAVE_FUNC_ATTRIBUTE_CONST
> +#define ATTRIBUTE_CONST __attribute__((__const__))
> +#else
> +#define ATTRIBUTE_CONST
> +#endif
> +
> #ifdef __cplusplus
> /**
> * Macro function that evaluates to true if T is a trivially
> --
> 2.1.4
Both of these hunks are alphabetized.
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