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 /configure.ac | |
| parent | d3a5dbfd1f18b89dd990ee83ece7c1dd9ba94b1a (diff) | |
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.
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 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) |