[svn-r19693] Bug 2008 - IBM Power6 Linux uses special conversion algorithms to convert some values from long

double to (unsigned) long and from (unsigned) long to long double.  I added tests in configure.in
to detect these algorithms.  Before I can figure out them, I disable the tests in dt_arith.c.

Tested on jam, heiwa, amani, IBM Power6 Linux machine in Holland (huygens.sara.nl).

1 files changed, 198 insertions, 1 deletions

diff --git a/configure b/configure
index 9d62b16..ed4128f 100755
--- a/configure
+++ b/configure
@@ -1,5 +1,5 @@
 #! /bin/sh
-# From configure.in Id: configure.in 19511 2010-10-05 13:28:37Z hdftest .
+# From configure.in Id: configure.in 19671 2010-10-27 01:54:11Z koziol .
 # Guess values for system-dependent variables and create Makefiles.
 # Generated by GNU Autoconf 2.67 for HDF5 1.8.7-snap1.
 #
@@ -27621,6 +27621,202 @@ else
 $as_echo "no" >&6; }
 fi
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking if using special algorithm to convert long double to (unsigned) long values" >&5
+$as_echo_n "checking if using special algorithm to convert long double to (unsigned) long values... " >&6; }
+
+if test ${ac_cv_sizeof_long_double} = 0; then
+   hdf5_cv_ldouble_to_long_special=${hdf5_cv_ldouble_to_long_special=no}
+else
+   if test "${hdf5_cv_ldouble_to_long_special+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+  if test "$cross_compiling" = yes; then :
+  { { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
+$as_echo "$as_me: error: in \`$ac_pwd':" >&2;}
+as_fn_error $? "cannot run test program while cross compiling
+See \`config.log' for more details" "$LINENO" 5; }
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+        int main(void)
+        {
+            long double         ld = 20041683600089727.779961L;
+            long                ll;
+            unsigned long       ull;
+            unsigned char       s[16];
+            unsigned char       s2[8];
+            int                 ret = 1;
+
+            if(sizeof(long double) == 16 && sizeof(long) == 8) {
+                /*make sure the long double type has 16 bytes in size and
+                 * 11 bits of exponent.  If it is,
+                 *the bit sequence should be like below.  It's not
+                 *a decent way to check but this info isn't available. */
+                memcpy(s, &ld, 16);
+                if(s[0]==0x43 && s[1]==0x51 && s[2]==0xcc && s[3]==0xf3 &&
+                    s[4]==0x85 && s[5]==0xeb && s[6]==0xc8 && s[7]==0xa0 &&
+                    s[8]==0xbf && s[9]==0xcc && s[10]==0x2a && s[11]==0x3c) {
+
+                    /* Assign the hexadecimal value of long double type. */
+                    s[0]=0x43; s[1]=0x51; s[2]=0xcc; s[3]=0xf3;
+                    s[4]=0x85; s[5]=0xeb; s[6]=0xc8; s[7]=0xa0;
+                    s[8]=0xbf; s[9]=0xcc; s[10]=0x2a; s[11]=0x3c;
+                    s[12]=0x3d; s[13]=0x85; s[14]=0x56; s[15]=0x20;
+
+                    memcpy(&ld, s, 16);
+
+                    ll = (long)ld;
+                    memcpy(s2, &ll, 8);
+
+                    /* The library's algorithm converts it to 0x 00 47 33 ce 17 af 22 82
+                     * and gets wrong value 20041683600089730 on the IBM Power6 Linux.
+                     * But the IBM Power6 Linux converts it to 0x00 47 33 ce 17 af 22 7f
+                     * and gets the correct value 20041683600089727.  It uses some special
+                     * algorithm.  We're going to define the macro and skip the test until
+                     * we can figure out how they do it. */
+                    if(s2[0]==0x00 && s2[1]==0x47 && s2[2]==0x33 && s2[3]==0xce &&
+                       s2[4]==0x17 && s2[5]==0xaf && s2[6]==0x22 && s2[7]==0x7f)
+                        ret = 0;
+
+                    ull = (unsigned long)ld;
+                    memcpy(s2, &ull, 8);
+
+                    /* The unsigned long is the same as signed long. */
+                    if(s2[0]==0x00 && s2[1]==0x47 && s2[2]==0x33 && s2[3]==0xce &&
+                       s2[4]==0x17 && s2[5]==0xaf && s2[6]==0x22 && s2[7]==0x7f)
+                        ret = 0;
+                }
+            }
+
+    done:
+            exit(ret);
+        }
+
+_ACEOF
+if ac_fn_c_try_run "$LINENO"; then :
+  hdf5_cv_ldouble_to_long_special=yes
+else
+  hdf5_cv_ldouble_to_long_special=no
+fi
+rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext \
+  conftest.$ac_objext conftest.beam conftest.$ac_ext
+fi
+
+fi
+
+fi
+
+if test ${hdf5_cv_ldouble_to_long_special} = "yes"; then
+
+$as_echo "#define LDOUBLE_TO_LONG_SPECIAL 1" >>confdefs.h
+
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking if using special algorithm to convert (unsigned) long to long double values" >&5
+$as_echo_n "checking if using special algorithm to convert (unsigned) long to long double values... " >&6; }
+
+if test ${ac_cv_sizeof_long_double} = 0; then
+   hdf5_cv_long_to_ldouble_special=${hdf5_cv_long_to_ldouble_special=no}
+else
+   if test "${hdf5_cv_long_to_ldouble_special+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+  if test "$cross_compiling" = yes; then :
+  { { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
+$as_echo "$as_me: error: in \`$ac_pwd':" >&2;}
+as_fn_error $? "cannot run test program while cross compiling
+See \`config.log' for more details" "$LINENO" 5; }
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+        int main(void)
+        {
+            long double         ld;
+            long                ll;
+            unsigned long       ull;
+            unsigned char       s[16];
+            int                 flag=0, ret=1;
+
+            /*Determine if long double has 16 byte in size, 11 bit exponent, and
+             *the bias is 0x3ff */
+            if(sizeof(long double) == 16) {
+                ld = 1.0L;
+                memcpy(s, &ld, 16);
+                if(s[0]==0x3f && s[1]==0xf0 && s[2]==0x00 && s[3]==0x00 &&
+                    s[4]==0x00 && s[5]==0x00 && s[6]==0x00 && s[7]==0x00)
+                    flag = 1;
+            }
+
+            if(flag==1 && sizeof(long)==8) {
+                ll = 0x003fffffffffffffL;
+                ld = (long double)ll;
+                memcpy(s, &ld, 16);
+                /* The library converts the value to 0x434fffffffffffff8000000000000000.
+                 * In decimal it is 18014398509481982.000000, one value short of the original.
+                 * The IBM Power6 Linux converts it to 0x4350000000000000bff0000000000000.
+                 * The value is correct in decimal. It uses some special
+                 * algorithm.  We're going to define the macro and skip the test until
+                 * we can figure out how they do it. */
+                if(s[0]==0x43 && s[1]==0x50 && s[2]==0x00 && s[3]==0x00 &&
+                    s[4]==0x00 && s[5]==0x00 && s[6]==0x00 && s[7]==0x00 &&
+                    s[8]==0xbf && s[9]==0xf0 && s[10]==0x00 && s[11]==0x00 &&
+                    s[12]==0x00 && s[13]==0x00 && s[14]==0x00 && s[15]==0x00)
+                    ret = 0;
+            }
+            if(flag==1 && sizeof(unsigned long)==8) {
+                ull = 0xffffffffffffffffUL;
+                ld = (long double)ull;
+                memcpy(s, &ld, 16);
+                /* Use a different value from signed long to test. The problem is the same
+                 * for both long and unsigned long. The value is 18446744073709551615.
+                 * The library converts the value to 0x43effffffffffffffe000000000000000.
+                 * In decimal it's 18446744073709548544.000000, very different from the original.
+                 * The IBM Power6 Linux converts it to 0x43f0000000000000bff0000000000000.
+                 * The value is correct in decimal. It uses some special
+                 * algorithm.  We're going to define the macro and skip the test until
+                 * we can figure out how they do it. */
+                if(s[0]==0x43 && s[1]==0xf0 && s[2]==0x00 && s[3]==0x00 &&
+                    s[4]==0x00 && s[5]==0x00 && s[6]==0x00 && s[7]==0x00 &&
+                    s[8]==0xbf && s[9]==0xf0 && s[10]==0x00 && s[11]==0x00 &&
+                    s[12]==0x00 && s[13]==0x00 && s[14]==0x00 && s[15]==0x00)
+                    ret = 0;
+            }
+    done:
+            exit(ret);
+        }
+
+_ACEOF
+if ac_fn_c_try_run "$LINENO"; then :
+  hdf5_cv_long_to_ldouble_special=yes
+else
+  hdf5_cv_long_to_ldouble_special=no
+fi
+rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext \
+  conftest.$ac_objext conftest.beam conftest.$ac_ext
+fi
+
+fi
+
+fi
+
+if test ${hdf5_cv_long_to_ldouble_special} = "yes"; then
+
+$as_echo "#define LONG_TO_LDOUBLE_SPECIAL 1" >>confdefs.h
+
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking if correctly converting long double to (unsigned) long long values" >&5
 $as_echo_n "checking if correctly converting long double to (unsigned) long long values... " >&6; }
 
@@ -27701,6 +27897,7 @@ else
 $as_echo "no" >&6; }
 fi
 
+
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking if correctly converting (unsigned) long long to long double values" >&5
 $as_echo_n "checking if correctly converting (unsigned) long long to long double values... " >&6; }