Introduce likely/unlikely macros, use them in saa.c

Introduce the likely() and unlikely() macros, as used in Linux.
They are compiler-dependent hints that a particular boolean expression
is likely to be true or false, respectively.

Currently only implemented for gcc.

1 files changed, 12 insertions, 0 deletions

diff --git a/compiler.h b/compiler.h
index 01e1127..51f4983 100644
--- a/compiler.h
+++ b/compiler.h
@@ -110,4 +110,16 @@ char *strsep(char **, const char *);
 # define X86_MEMORY 0
 #endif
 
+/*
+ * Hints to the compiler that a particular branch of code is more or
+ * less likely to be taken.
+ */
+#if defined(__GNUC__) && __GNUC__ >= 3
+# define likely(x)	__builtin_expect(!!(x), 1)
+# define unlikely(x)	__builtin_expect(!!(x), 0)
+#else
+# define likely(x)	(!!(x))
+# define unlikely(x)	(!!(x))
+#endif
+
 #endif	/* NASM_COMPILER_H */