[core] check for __builtin_expect() availability

3 years ago · 647222b35c
parent 730c932e3c
commit 647222b35c
1 changed files with 11 additions and 0 deletions
--- a/src/first.h
+++ b/src/first.h
@ -60,6 +60,10 @@
 #define __has_attribute(x) 0
 #endif

+#ifndef __has_builtin         /* clang */
+#define __has_builtin(x) 0
+#endif
+
 #ifdef __GNUC__
 #ifndef __GNUC_PREREQ
 #  ifdef __GNUC_PREREQ__
@ -75,6 +79,13 @@
 #define __GNUC_PREREQ(maj,min) 0
 #endif

+#ifndef __builtin_expect
+#if !__has_builtin(__builtin_expect) \
+ && !__GNUC_PREREQ(2,96)
+#define __builtin_expect(x,y) (x)
+#endif
+#endif
+
 #ifndef __attribute_noinline__
 #if __has_attribute(noinline) \
 || __GNUC_PREREQ(3,1)