clang has __builtin_clz, __builtin_clzl, __builtin_clzll, also on Windows.
At least in versions >= 4.0.0.
2020-08-05 Bruno Haible <br...@clisp.org>
Use __builtin_clz{,l,ll} with clang, also on Windows.
* lib/integer_length.c: With clang, use the GCC built-in, not
<intrin.h>.
* lib/integer_length_l.c: Likewise.
* lib/count-leading-zeros.h (COUNT_LEADING_ZEROS): Use the GCC built-in
also on clang.
* lib/vasnprintf.c (divide): Likewise.
diff --git a/lib/count-leading-zeros.h b/lib/count-leading-zeros.h
index 7e88c8c..7cf605a 100644
--- a/lib/count-leading-zeros.h
+++ b/lib/count-leading-zeros.h
@@ -38,7 +38,8 @@ extern "C" {
expand to code that computes the number of leading zeros of the local
variable 'x' of type TYPE (an unsigned integer type) and return it
from the current function. */
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
+#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) \
+ || (__clang_major__ >= 4)
# define COUNT_LEADING_ZEROS(BUILTIN, MSC_BUILTIN, TYPE) \
return x ? BUILTIN (x) : CHAR_BIT * sizeof x;
#elif _MSC_VER
diff --git a/lib/integer_length.c b/lib/integer_length.c
index 43d8f49..1896c6a 100644
--- a/lib/integer_length.c
+++ b/lib/integer_length.c
@@ -25,7 +25,7 @@
#include "float+.h"
-#if defined _MSC_VER
+#if defined _MSC_VER && !(__clang_major__ >= 4)
# include <intrin.h>
#endif
@@ -34,7 +34,7 @@
int
integer_length (unsigned int x)
{
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
+#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || (__clang_major__
>= 4)
if (x == 0)
return 0;
else
diff --git a/lib/integer_length_l.c b/lib/integer_length_l.c
index 161f1af..907a6db 100644
--- a/lib/integer_length_l.c
+++ b/lib/integer_length_l.c
@@ -41,7 +41,7 @@
# define MSVC_BUILTIN _BitScanReverse
#endif
-#if defined _MSC_VER
+#if defined _MSC_VER && !(__clang_major__ >= 4)
# include <intrin.h>
/* Copied from integer_length.c. */
static inline int
@@ -66,7 +66,7 @@ integer_length (unsigned int x)
int
FUNC (TYPE x)
{
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
+#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || (__clang_major__
>= 4)
if (x == 0)
return 0;
else
diff --git a/lib/vasnprintf.c b/lib/vasnprintf.c
index 0cdc6c0..7f75139 100644
--- a/lib/vasnprintf.c
+++ b/lib/vasnprintf.c
@@ -633,7 +633,8 @@ divide (mpn_t a, mpn_t b, mpn_t *q)
mp_limb_t msd = b_ptr[b_len - 1]; /* = b[n-1], > 0 */
/* Determine s = GMP_LIMB_BITS - integer_length (msd).
Code copied from gnulib's integer_length.c. */
-# if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
+# if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) \
+ || (__clang_major__ >= 4)
s = __builtin_clz (msd);
# else
# if defined DBL_EXPBIT0_WORD && defined DBL_EXPBIT0_BIT
