[svn-r8491] Purpose: Bug fix

Description:  For certain compiler(PGI we know so far), during conversion
from float or double to unsigned long long, it does round-up when the
fraction part is greater than 0.5, which shouldn't happen.

Solution:  check it during configuration and compensate this offset
during testing in dtypes.

Platforms tested:  verbena and fuss.  verbena is the only machine with
PGI compiler. Ran it on fuss to verify it with other compiler.

1 files changed, 70 insertions, 0 deletions

diff --git a/configure b/configure
index bd89456..18c3c6a 100755
--- a/configure
+++ b/configure
@@ -33384,6 +33384,76 @@ else
 echo "${ECHO_T}no" >&6
 fi
 
+echo "$as_me:$LINENO: checking if accurately converting floating-point to unsigned long long values works" >&5
+echo $ECHO_N "checking if accurately converting floating-point to unsigned long long values works... $ECHO_C" >&6
+
+if test "${hdf5_cv_fp_to_ullong_bottom_bit_works+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+  if test "$cross_compiling" = yes; then
+  { { echo "$as_me:$LINENO: error: cannot run test program while cross compiling" >&5
+echo "$as_me: error: cannot run test program while cross compiling" >&2;}
+   { (exit 1); exit 1; }; }
+else
+  cat >conftest.$ac_ext <<_ACEOF
+#line $LINENO "configure"
+#include "confdefs.h"
+
+    int main(void)
+    {
+        float f = 111.60;
+        double d = 222.55;
+        unsigned long long l1 = (unsigned long long)f;
+        unsigned long long l2 = (unsigned long long)d;
+        int           ret = 0;
+
+        if(l1 == 112)
+            ret = 1;
+        if(l2 == 223)
+            ret = 1;
+
+done:
+        exit(ret);
+    }
+
+_ACEOF
+rm -f conftest$ac_exeext
+if { (eval echo "$as_me:$LINENO: \"$ac_link\"") >&5
+  (eval $ac_link) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && { ac_try='./conftest$ac_exeext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  hdf5_cv_fp_to_ullong_bottom_bit_works=yes
+else
+  echo "$as_me: program exited with status $ac_status" >&5
+echo "$as_me: failed program was:" >&5
+cat conftest.$ac_ext >&5
+( exit $ac_status )
+hdf5_cv_fp_to_ullong_bottom_bit_works=no
+fi
+rm -f core core.* *.core conftest$ac_exeext conftest.$ac_objext conftest.$ac_ext
+fi
+fi
+
+
+if test ${hdf5_cv_fp_to_ullong_bottom_bit_works} = "yes"; then
+
+cat >>confdefs.h <<\_ACEOF
+#define FP_TO_ULLONG_BOTTOM_BIT_WORKS 1
+_ACEOF
+
+  echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6
+else
+  echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6
+fi
+
 echo "$as_me:$LINENO: checking if compiling unsigned long long to floating-point typecasts work" >&5
 echo $ECHO_N "checking if compiling unsigned long long to floating-point typecasts work... $ECHO_C" >&6
 if test "${hdf5_cv_ullong_to_fp_cast_works+set}" = set; then