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| author | Wladimir J. van der Laan <laanwj@protonmail.com> | 2020-06-29 15:49:04 +0200 |
|---|---|---|
| committer | Wladimir J. van der Laan <laanwj@protonmail.com> | 2020-06-29 15:49:08 +0200 |
| commit | 1269cab21a9ac32f9ee8adfb9041950756eff3e4 (patch) | |
| tree | 0aa35bf319bc051a9536d14730ae976435ba37ea /configure.ac | |
| parent | 8edfc1715a02cbaf52420d3c4e71f67ff9af0b41 (diff) | |
| parent | 9952242c03fe587b5dff46a9f770e319146103bf (diff) | |
| download | bitcoin-1269cab21a9ac32f9ee8adfb9041950756eff3e4.tar.xz | |
Merge #19403: build: improve __builtin_clz* detection
9952242c03fe587b5dff46a9f770e319146103bf build: improve builtin_clz* detection (fanquake)
Pull request description:
Fixes #19402.
The way we currently test for `__builtin_clz*` support with `AC_CHECK_DECLS` does 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. If this is controversial then I'll add a test for it as well.
ACKs for top commit:
sipa:
ACK 9952242c03fe587b5dff46a9f770e319146103bf
laanwj:
ACK 9952242c03fe587b5dff46a9f770e319146103bf
Tree-SHA512: 695abb1a694a01a25aaa483b4fffa7d598842f2ba4fe8630fbed9ce5450b915c33bf34bb16ad16a16b702dd7c91ebf49fe509a2498b9e28254fe0ec5177bbac0
Diffstat (limited to 'configure.ac')
| -rw-r--r-- | configure.ac | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/configure.ac b/configure.ac index 8f5a183dde..75ed9256d9 100644 --- a/configure.ac +++ b/configure.ac @@ -850,7 +850,21 @@ 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) |