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-rw-r--r--build_msvc/bitcoin_config.h12
-rw-r--r--configure.ac16
-rw-r--r--src/crypto/common.h4
3 files changed, 17 insertions, 15 deletions
diff --git a/build_msvc/bitcoin_config.h b/build_msvc/bitcoin_config.h
index 35ba8425b3..fbbe1a2156 100644
--- a/build_msvc/bitcoin_config.h
+++ b/build_msvc/bitcoin_config.h
@@ -137,18 +137,6 @@
don't. */
#define HAVE_DECL_STRNLEN 1
-/* Define to 1 if you have the declaration of `__builtin_clz', and to 0 if you
- don't. */
-//#define HAVE_DECL___BUILTIN_CLZ 1
-
-/* Define to 1 if you have the declaration of `__builtin_clzl', and to 0 if
- you don't. */
-//#define HAVE_DECL___BUILTIN_CLZL 1
-
-/* Define to 1 if you have the declaration of `__builtin_clzll', and to 0 if
- you don't. */
-//#define HAVE_DECL___BUILTIN_CLZLL 1
-
/* Define to 1 if you have the <dlfcn.h> header file. */
/* #undef HAVE_DLFCN_H */
diff --git a/configure.ac b/configure.ac
index 12bece6903..0c7573c313 100644
--- a/configure.ac
+++ b/configure.ac
@@ -849,7 +849,21 @@ AC_CHECK_DECLS([bswap_16, bswap_32, bswap_64],,,
#include <byteswap.h>
#endif])
-AC_CHECK_DECLS([__builtin_clz, __builtin_clzl, __builtin_clzll])
+AC_MSG_CHECKING(for __builtin_clzl)
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[ ]], [[
+ (void) __builtin_clzl(0);
+ ]])],
+ [ AC_MSG_RESULT(yes); AC_DEFINE(HAVE_BUILTIN_CLZL, 1, [Define this symbol if you have __builtin_clzl])],
+ [ AC_MSG_RESULT(no)]
+)
+
+AC_MSG_CHECKING(for __builtin_clzll)
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[ ]], [[
+ (void) __builtin_clzll(0);
+ ]])],
+ [ AC_MSG_RESULT(yes); AC_DEFINE(HAVE_BUILTIN_CLZLL, 1, [Define this symbol if you have __builtin_clzll])],
+ [ AC_MSG_RESULT(no)]
+)
dnl Check for malloc_info (for memory statistics information in getmemoryinfo)
AC_MSG_CHECKING(for getmemoryinfo)
diff --git a/src/crypto/common.h b/src/crypto/common.h
index e7bb020a19..5b4932c992 100644
--- a/src/crypto/common.h
+++ b/src/crypto/common.h
@@ -82,12 +82,12 @@ void static inline WriteBE64(unsigned char* ptr, uint64_t x)
/** Return the smallest number n such that (x >> n) == 0 (or 64 if the highest bit in x is set. */
uint64_t static inline CountBits(uint64_t x)
{
-#if HAVE_DECL___BUILTIN_CLZL
+#if HAVE_BUILTIN_CLZL
if (sizeof(unsigned long) >= sizeof(uint64_t)) {
return x ? 8 * sizeof(unsigned long) - __builtin_clzl(x) : 0;
}
#endif
-#if HAVE_DECL___BUILTIN_CLZLL
+#if HAVE_BUILTIN_CLZLL
if (sizeof(unsigned long long) >= sizeof(uint64_t)) {
return x ? 8 * sizeof(unsigned long long) - __builtin_clzll(x) : 0;
}