[svn-r27428] Bug fix: DAILYTEST-170

Description:
    XL compilers in ostrich (PowerPC64 linux) fail in test/dt_arith
    because of the removal of the LLONG_TO_LDOUBLE_CORRECT (removed in
    r26625) and LDOUBLE_TO_LLONG_ACCURATE (removed in r26623).

Solution:
    Reverse revisions
	r26623: bring back LDOUBLE_TO_LLONG_ACCURATE configure macro
	r26625: bring back LLONG_TO_LDOUBLE_CORRECT configure macro
	r26627: bring back WANT_DATA_ACCURACY configure macro which is
	    used together with the above two macros. This also brings
	    back the enable-dconv-accuracy configure option.

Tested:
    h5committested.
    Also tested in ostrich using the XL compilers.

1 files changed, 153 insertions, 0 deletions

diff --git a/configure.ac b/configure.ac
index 5dd93b4..5418f28 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2269,6 +2269,27 @@ else
 fi
 
 ## ----------------------------------------------------------------------
+## Decide whether the data accuracy has higher priority during data
+## conversions.  If not, some hard conversions will still be prefered even
+## though the data may be wrong (for example, some compilers don't 
+## support denormalized floating values) to maximize speed.
+## 
+AC_MSG_CHECKING([whether data accuracy is guaranteed during data conversions])
+AC_ARG_ENABLE([dconv-accuracy],
+              [AS_HELP_STRING([--enable-dconv-accuracy],
+                              [if data accuracy is guaranteed during 
+                              data conversions [default=yes]])],
+              [DATA_ACCURACY=$enableval], [DATA_ACCURACY=yes])
+
+if test "$DATA_ACCURACY" = "yes"; then
+  AC_MSG_RESULT([yes])
+  AC_DEFINE([WANT_DATA_ACCURACY], [1],
+            [Data accuracy is prefered to speed during data conversions])
+else
+  AC_MSG_RESULT([no])
+fi
+
+## ----------------------------------------------------------------------
 ## Set the flag to indicate that the machine has window style pathname,
 ## that is, "drive-letter:\" (e.g. "C:") or "drive-letter:/" (e.g. "C:/").
 ## (This flag should be _unset_ for all machines, except for Windows, where
@@ -2448,6 +2469,138 @@ else
 fi
 
 ## ----------------------------------------------------------------------
+## Set the flag to indicate that the machine can accurately convert
+## 'long double' to '(unsigned) long long' values.  (This flag should
+## be set for all machines, except for Mac OS 10.4, SGI IRIX64 6.5 and
+## Powerpc Linux using XL compilers.
+## When the bit sequence of long double is 0x4351ccf385ebc8a0bfcc2a3c...,
+## the values of (unsigned)long long start to go wrong on these
+## two machines.  Adjusting it higher to 0x4351ccf385ebc8a0dfcc... or
+## 0x4351ccf385ebc8a0ffcc... will make the converted values wildly wrong.
+## This test detects this wrong behavior and disable the test.
+##
+AC_MSG_CHECKING([if correctly converting long double to (unsigned) long long values])
+
+if test ${ac_cv_sizeof_long_double} = 0; then
+   hdf5_cv_ldouble_to_llong_accurate=${hdf5_cv_ldouble_to_llong_accurate=no}
+else
+   AC_CACHE_VAL([hdf5_cv_ldouble_to_llong_accurate],
+        [AC_TRY_RUN([
+        int main(void)
+        {
+            long double         ld = 20041683600089727.779961L;
+            long long           ll;
+            unsigned long long  ull;
+            unsigned char       s[16];
+            int                 ret = 0;
+            
+            if(sizeof(long double) == 16) {
+                /*make sure the long double type is the same as the failing type 
+                 *which 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) {
+
+                    /*slightly adjust the bit sequence (s[8]=0xdf).  The converted
+                     *values will go wild on Mac OS 10.4 and IRIX64 6.5.*/ 
+                    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]=0xdf; 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 long)ld;
+                    ull = (unsigned long long)ld;
+                    
+                    if(ll != 20041683600089728 || ull != 20041683600089728)
+                        ret = 1;
+                }    
+            }    
+    done:
+            exit(ret);
+        }
+        ], [hdf5_cv_ldouble_to_llong_accurate=yes], [hdf5_cv_ldouble_to_llong_accurate=no],)])
+fi
+
+if test ${hdf5_cv_ldouble_to_llong_accurate} = "yes"; then
+  AC_DEFINE([LDOUBLE_TO_LLONG_ACCURATE], [1],
+            [Define if your system can convert long double to (unsigned) long long values correctly.])
+  AC_MSG_RESULT([yes])
+else
+  AC_MSG_RESULT([no])
+fi
+
+
+## ----------------------------------------------------------------------
+## Set the flag to indicate that the machine can accurately convert
+## '(unsigned) long long' to 'long double' values.  (This flag should be
+## set for all machines, except for Mac OS 10.4 and Powerpc Linux using
+## XL compilers.
+## When the bit sequences are 003fff..., 007fff..., 00ffff..., 01ffff...,
+## ..., 7fffff..., the converted values are twice as big as they should be.
+##
+AC_MSG_CHECKING([if correctly converting (unsigned) long long to long double values])
+
+if test ${ac_cv_sizeof_long_double} = 0; then
+   hdf5_cv_llong_to_ldouble_correct=${hdf5_cv_llong_to_ldouble_correct=no}
+else
+   AC_CACHE_VAL([hdf5_cv_llong_to_ldouble_correct],
+        [AC_TRY_RUN([
+        int main(void)
+        {
+            long double         ld;
+            long long           ll;
+            unsigned long long  ull;
+            unsigned char       s[16];
+            int                 flag=0, ret=0;
+        
+            /*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 long)==8) {
+                ll = 0x01ffffffffffffffLL;
+                ld = (long double)ll;
+                memcpy(s, &ld, 16);
+                /*Check if the bit sequence is as supposed to be*/
+                if(s[0]!=0x43 || s[1]!=0x7f || s[2]!=0xff || s[3]!=0xff ||
+                    s[4]!=0xff || s[5]!=0xff || s[6]!=0xff || s[7]!=0xff ||
+                    s[8]!=0xf0 || s[9]!=0x00 || s[10]!=0x00 || s[11]!=0x00)
+                    ret = 1;
+            }        
+            if(flag==1 && sizeof(unsigned long long)==8) {
+                ull = 0x01ffffffffffffffULL;
+                ld = (long double)ull;
+                memcpy(s, &ld, 16);
+                if(s[0]!=0x43 || s[1]!=0x7f || s[2]!=0xff || s[3]!=0xff ||
+                    s[4]!=0xff || s[5]!=0xff || s[6]!=0xff || s[7]!=0xff ||
+                    s[8]!=0xf0 || s[9]!=0x00 || s[10]!=0x00 || s[11]!=0x00)
+                    ret = 1;
+            }        
+    done:
+            exit(ret);
+        }
+        ], [hdf5_cv_llong_to_ldouble_correct=yes], [hdf5_cv_llong_to_ldouble_correct=no],)])
+fi
+
+if test ${hdf5_cv_llong_to_ldouble_correct} = "yes"; then
+  AC_DEFINE([LLONG_TO_LDOUBLE_CORRECT], [1],
+            [Define if your system can convert (unsigned) long long to long double values correctly.])
+  AC_MSG_RESULT([yes])
+else
+  AC_MSG_RESULT([no])
+fi
+
+## ----------------------------------------------------------------------
 ## Set some variables for general configuration information to be saved
 ## and installed with the libraries (used to generate libhdf5.settings).
 ##