Commit be1f49bd authored by Eric Anholt's avatar Eric Anholt

mesa: Detect and provide macros for function attributes pure and const.

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.

v2: Alphabetize.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org> (v1)
parent bde4c8ec
......@@ -205,10 +205,12 @@ AX_GCC_BUILTIN([__builtin_popcount])
AX_GCC_BUILTIN([__builtin_popcountll])
AX_GCC_BUILTIN([__builtin_unreachable])
AX_GCC_FUNC_ATTRIBUTE([const])
AX_GCC_FUNC_ATTRIBUTE([flatten])
AX_GCC_FUNC_ATTRIBUTE([format])
AX_GCC_FUNC_ATTRIBUTE([malloc])
AX_GCC_FUNC_ATTRIBUTE([packed])
AX_GCC_FUNC_ATTRIBUTE([pure])
AX_GCC_FUNC_ATTRIBUTE([unused])
AX_GCC_FUNC_ATTRIBUTE([warn_unused_result])
......
......@@ -103,6 +103,17 @@ do { \
#define assume(expr) assert(expr)
#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 HAVE_FUNC_ATTRIBUTE_FLATTEN
#define FLATTEN __attribute__((__flatten__))
#else
......@@ -130,6 +141,15 @@ 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
#ifdef __cplusplus
/**
* Macro function that evaluates to true if T is a trivially
......
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