From 697e1d02f53f985992a4f479b0b08fca5c272c6c Mon Sep 17 00:00:00 2001 From: David Rowley Date: Tue, 24 Nov 2020 11:29:28 +1300 Subject: [PATCH] Define pg_attribute_cold and pg_attribute_hot macros For compilers supporting __has_attribute and __has_attribute (hot/cold). __has_attribute is supported on gcc >= 5, clang >= 2.9 and icc >= 17. A followup commit will implement some usages of these macros. Author: David Rowley Reviewed-by: Andres Freund, Peter Eisentraut Discussion: https://postgr.es/m/CAApHDvrVpasrEzLL2er7p9iwZFZ%3DJj6WisePcFeunwfrV0js_A%40mail.gmail.com --- src/include/c.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/src/include/c.h b/src/include/c.h index d5dc3632f74..ff7c2eddcec 100644 --- a/src/include/c.h +++ b/src/include/c.h @@ -191,6 +191,22 @@ #define pg_noinline #endif +/* + * Marking certain functions as "hot" or "cold" can be useful to assist the + * compiler in arranging the assembly code in a more efficient way. + */ +#if defined(__has_attribute) && __has_attribute (cold) +#define pg_attribute_cold __attribute__((cold)) +#else +#define pg_attribute_cold +#endif + +#if defined(__has_attribute) && __has_attribute (hot) +#define pg_attribute_hot __attribute__((hot)) +#else +#define pg_attribute_hot +#endif + /* * Mark a point as unreachable in a portable fashion. This should preferably * be something that the compiler understands, to aid code generation.