vppinfra: add COMPILE_TIME_CONST() macro

[vpp.git] / src / vppinfra / clib.h

diff --git a/src/vppinfra/clib.h b/src/vppinfra/clib.h
index 22377c6..4629a7d 100644 (file)
--- a/src/vppinfra/clib.h
+++ b/src/vppinfra/clib.h
@@ -120,6 +120,7 @@
 /* Hints to compiler about hot/cold code. */
 #define PREDICT_FALSE(x) __builtin_expect((x),0)
 #define PREDICT_TRUE(x) __builtin_expect((x),1)
+#define COMPILE_TIME_CONST(x) __builtin_constant_p (x)
 
 /*
  * Compiler barrier
@@ -158,6 +159,16 @@
 #endif
 
 #if defined (count_leading_zeros)
+always_inline uword
+clear_lowest_set_bit (uword x)
+{
+#ifdef __BMI2__
+  return _blsr_u64 (x);
+#else
+  return x ^ (1ULL << count_trailing_zeros (x));
+#endif
+}
+
 always_inline uword
 min_log2 (uword x)
 {