diff options
author | fanquake <fanquake@gmail.com> | 2020-06-29 11:24:25 +0800 |
---|---|---|
committer | fanquake <fanquake@gmail.com> | 2020-06-29 11:31:17 +0800 |
commit | 9952242c03fe587b5dff46a9f770e319146103bf (patch) | |
tree | 6177b4850642e0ed13144fe421cd2b3dc07e6497 | |
parent | d3a5dbfd1f18b89dd990ee83ece7c1dd9ba94b1a (diff) | |
download | bitcoin-9952242c03fe587b5dff46a9f770e319146103bf.tar.xz |
build: improve builtin_clz* detection
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:100:10: 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.
-rw-r--r-- | build_msvc/bitcoin_config.h | 12 | ||||
-rw-r--r-- | configure.ac | 16 | ||||
-rw-r--r-- | src/crypto/common.h | 4 |
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; } |