diff options
| author | Stephan Bergmann <sbergman@redhat.com> | 2020-04-17 12:10:00 +0200 |
|---|---|---|
| committer | Stephan Bergmann <sbergman@redhat.com> | 2020-04-17 15:24:07 +0200 |
| commit | 870ab3b8492fa7d42c56ca09884811fef1695d28 (patch) | |
| tree | 6d5bc07f7e443709eeb36652141b733f848794ce /configure.ac | |
| parent | 0a0c10c0502906bebf9ea8c732d63809d5080dd6 (diff) | |
Just use __builtin_ffs on GCC and Clang
GCC appears to support it at least since <https://gcc.gnu.org/git/
?p=gcc.git;a=commit;h=51e2940139d5e3e86590f6e6802ffc3f3010be5b> "Initial
revision" in 1992, and Clang appears to support it since <https://github.com/
llvm/llvm-project/commit/d93abc3bb0acdd430839abdd67bd3920fee87bbc> "Implement
ffs, parity, and popcount builtins" in Clang 2.4. (And if a build used a
compiler that does not support it, there would be no guarantee that it would
support strings.h function ffs from X/Open System Interfaces, either.)
Introducing HAVE_GCC_BUILTIN_FFS in 334a9f16cd1d1f9694f885c759903a41aa3d4833
"tdf#113211: fix calculations with big integers" appears to be due to a
misguided recommendation at <https://gerrit.libreoffice.org/c/core/+/43477/4#
message-899806c724fbdcece0ea9438514a6a5db6a2e645>.
Change-Id: Ib6ee6de548172b3aae25483d03efb86620133933
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/92421
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>
Diffstat (limited to 'configure.ac')
| -rw-r--r-- | configure.ac | 9 |
1 files changed, 0 insertions, 9 deletions
diff --git a/configure.ac b/configure.ac index 57a243841505..1eb9a1af7898 100644 --- a/configure.ac +++ b/configure.ac @@ -6304,15 +6304,6 @@ if test "$GCC" = "yes" -o "$COM_IS_CLANG" = TRUE; then AC_MSG_RESULT([no]) fi - AC_MSG_CHECKING([whether $CC_BASE supports __builtin_ffs]) - AC_LINK_IFELSE([AC_LANG_PROGRAM([[]], [[ return __builtin_ffs(1); ]])],[HAVE_GCC_BUILTIN_FFS=TRUE],[]) - if test "$HAVE_GCC_BUILTIN_FFS" = "TRUE"; then - AC_MSG_RESULT([yes]) - AC_DEFINE(HAVE_GCC_BUILTIN_FFS) - else - AC_MSG_RESULT([no]) - fi - AC_MSG_CHECKING([whether $CC_BASE supports __attribute__((deprecated(message)))]) save_CFLAGS=$CFLAGS CFLAGS="$CFLAGS -Werror" |