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Detect if 8-bit atomics are available.

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In some rare cases (older compiler, e.g. gcc 4.2 w/ MIPS), 8-bit atomics might
be unavailable.  Detect such cases so that we can workaround.
This commit is contained in:
Qi Wang
2019-03-07 15:58:26 -08:00
committed by Qi Wang
parent 14d3686c9f
commit 06f0850427
3 changed files with 39 additions and 0 deletions
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25
configure.ac
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@@ -1896,6 +1896,19 @@ JE_COMPILABLE([GCC __atomic atomics], [
], [je_cv_gcc_atomic_atomics])
if test "x${je_cv_gcc_atomic_atomics}" = "xyes" ; then
AC_DEFINE([JEMALLOC_GCC_ATOMIC_ATOMICS])
dnl check for 8-bit atomic support
JE_COMPILABLE([GCC 8-bit __atomic atomics], [
], [
unsigned char x = 0;
int val = 1;
int y = __atomic_fetch_add(&x, val, __ATOMIC_RELAXED);
int after_add = (int)x;
return after_add == 1;
], [je_cv_gcc_u8_atomic_atomics])
if test "x${je_cv_gcc_u8_atomic_atomics}" = "xyes" ; then
AC_DEFINE([JEMALLOC_GCC_U8_ATOMIC_ATOMICS])
fi
fi
dnl ============================================================================
@@ -1910,6 +1923,18 @@ JE_COMPILABLE([GCC __sync atomics], [
], [je_cv_gcc_sync_atomics])
if test "x${je_cv_gcc_sync_atomics}" = "xyes" ; then
AC_DEFINE([JEMALLOC_GCC_SYNC_ATOMICS])
dnl check for 8-bit atomic support
JE_COMPILABLE([GCC 8-bit __sync atomics], [
], [
unsigned char x = 0;
int before_add = __sync_fetch_and_add(&x, 1);
int after_add = (int)x;
return (before_add == 0) && (after_add == 1);
], [je_cv_gcc_u8_sync_atomics])
if test "x${je_cv_gcc_u8_sync_atomics}" = "xyes" ; then
AC_DEFINE([JEMALLOC_GCC_U8_SYNC_ATOMICS])
fi
fi
dnl ============================================================================