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build: improve builtin_clz* detection

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The way we currently test with AC_CHECK_DECLS do not work with Clang:
```bash
configure:21492: clang++-10 -std=c++11 -c -g -O2  -DHAVE_BUILD_INFO -D__STDC_FORMAT_MACROS conftest.cpp >&5
conftest.cpp💯10: error: builtin functions must be directly called
  (void) __builtin_clz;
         ^
1 error generated.
```

This also removes the __builtin_clz() check, as we don't actually use
it anywhere, and it's trvial to re-add detection if we do start using
it at some point.
This commit is contained in:
fanquake 2020-06-29 11:24:25 +08:00
parent d3a5dbfd1f
commit 9952242c03
No known key found for this signature in database
GPG key ID: 2EEB9F5CC09526C1
3 changed files with 17 additions and 15 deletions
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12
build_msvc/bitcoin_config.h
View file

@ -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 */

16
configure.ac
View file

@ -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)

4
src/crypto/common.h
View file

@ -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;
}