diff options
Diffstat (limited to 'Zend/Zend.m4')
| -rw-r--r-- | Zend/Zend.m4 | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/Zend/Zend.m4 b/Zend/Zend.m4 index 904f188681..bf9be5c7f8 100644 --- a/Zend/Zend.m4 +++ b/Zend/Zend.m4 @@ -117,6 +117,38 @@ AC_CHECK_FUNCS(finite isfinite isinf isnan) ZEND_FP_EXCEPT ZEND_CHECK_FLOAT_PRECISION + +dnl test whether double cast to long preserves least significant bits +AC_MSG_CHECKING(whether double cast to long preserves least significant bits) + +AC_TRY_RUN([ +#include <limits.h> + +int main() +{ + if (sizeof(long) == 4) { + double d = (double) LONG_MIN * LONG_MIN + 2e9; + + if ((long) d == 2e9 && (long) -d == -2e9) { + exit(0); + } + } else if (sizeof(long) == 8) { + double correct = 18e18 - ((double) LONG_MIN * -2); /* Subtract ULONG_MAX + 1 */ + + if ((long) 18e18 == correct) { /* On 64-bit, only check between LONG_MAX and ULONG_MAX */ + exit(0); + } + } + exit(1); +} +], [ + AC_DEFINE([ZEND_DVAL_TO_LVAL_CAST_OK], 1, [Define if double cast to long preserves least significant bits]) + AC_MSG_RESULT(yes) +], [ + AC_MSG_RESULT(no) +], [ + AC_MSG_RESULT(no) +]) ]) |