[Bug math/13563] New: LoP asinl returns unexpected value on long double

[Bug math/13563] New: LoP asinl returns unexpected value on long double

[guojiufu at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13563

             Bug #: 13563
           Summary: LoP asinl returns unexpected value on long double
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: math
        AssignedTo: aj@suse.de
        ReportedBy: guojiufu@gmail.com
    Classification: Unclassified


#include <stdio.h>
#include <float.h>
#include <math.h>

typedef union { long double ld; struct{long l1, l2, l3, l4;} s; } U ;

int main(void) {
   U u ;
   long double arg = (1.L-((__extension__ 0x1p-105L))/(long double)2);
   long double a = asinl(arg);

   u.ld = arg ;
   printf("size of long double=%d long=%d\n", sizeof(long double),
sizeof(long));
   printf("%X %X %X %X\n", u.s.l1,u.s.l2,u.s.l3,u.s.l4);
   printf("%.30Lg\n",arg);
   printf("%.30Lg\n",a);

 return 0;
}

> gcc t.c -lm;./a.out

EXPECTED OUTPUT:

size of long double=8 long=4
3FF00000 0 FE97FF4 0
1
1.57079632679489655799898173427


ACTUAL OUTPUT:
size of long double=16 long=4
3FF00000 0 B9500000 0
1
nan   <-should be 1.570796326794....

This issue happens at Linux on Power system

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[Bug math/13563] LoP asinl returns unexpected value on long double

[aj at suse dot de]

http://sourceware.org/bugzilla/show_bug.cgi?id=13563

Andreas Jaeger <aj at suse dot de> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|aj at suse dot de           |sjmunroe at us dot ibm.com

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[Bug math/13563] LoP asinl returns unexpected value on long double

[sjmunroe at us dot ibm.com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13563

Steven Munroe <sjmunroe at us dot ibm.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED

--- Comment #1 from Steven Munroe <sjmunroe at us dot ibm.com> 2012-01-05 14:44:59 UTC ---
I did not see any info on which distro and release?

But it looks like this is fixed up stream, And the fix is available via the
advance toolchain:
http://ausgsa.ibm.com/projects/p/ppctoolchain/web/public/at/at5.0/suse/SLES_10/

sjmunroe@spokane1:~/src> export PATH=/opt/at5.0/bin:$PATH
sjmunroe@spokane1:~/src> gcc -O2 -g bugz-13563.c -lm -o bugz-13563
sjmunroe@spokane1:~/src> ./bugz-13563
size of long double=16 long=8
0 0 0 37DF8
1
1.57079632679489646222207582326

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[Bug math/13563] LoP asinl returns unexpected value on long double

[sjmunroe at us dot ibm.com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13563

Steven Munroe <sjmunroe at us dot ibm.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|FIXED                       |

--- Comment #2 from Steven Munroe <sjmunroe at us dot ibm.com> 2012-01-05 19:19:01 UTC ---
Oops false resolve, seems the GCC-4.6 compiler will optimize the asinl call
away and load the correct const result for -O1 or higher. I see the same
failure when compiled at -O0.

The team will take a closer look.

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[Bug math/13563] LoP asinl returns unexpected value on long double

[dflahert at us dot ibm.com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13563

Dave Flaherty <dflahert at us dot ibm.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dflahert at us dot ibm.com

--- Comment #3 from Dave Flaherty <dflahert at us dot ibm.com> 2012-01-24 21:02:41 UTC ---
It appears there are a couple issues with this code.  The first issue is how
the code is checking for values greater than 1 (or less than -1), and the other
issue is how the code gets the absolute value of the input argument. 

Patch and test suite update will be provided shortly.

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[Bug math/13563] LoP asinl returns unexpected value on long double

[dflahert at us dot ibm.com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13563

--- Comment #4 from Dave Flaherty <dflahert at us dot ibm.com> 2012-02-16 17:13:29 UTC ---
Created attachment 6223
  --> http://sourceware.org/bugzilla/attachment.cgi?id=6223
patch with updates to e_asinl.c and libm-test.inc

* sysdeps/ieee754/ldbl-128ibm/e_asinl.c (__ieee754_asinl): Updated the |x|  
  code and specifically check for |x|>1.
* math/libm-test.inc (asin_test): Added a long double and  
  LDBL_MANT_DIG == 106 test for values near |1|.

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[Bug math/13563] LoP asinl returns unexpected value on long double

[jsm28 at gcc dot gnu.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=13563

--- Comment #5 from Joseph Myers <jsm28 at gcc dot gnu.org> 2012-03-02 00:58:24 UTC ---
The patch should be posted to libc-alpha for review.

You shouldn't be updating copyright dates in a copyright notice in the name of
Sun, only those in FSF copyright notices....

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[Bug math/13563] LoP asinl returns unexpected value on long double

[azanella at linux dot vnet.ibm.com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13563

Adhemerval Zanella Netto <azanella at linux dot vnet.ibm.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |azanella at linux dot
                   |                            |vnet.ibm.com

--- Comment #6 from Adhemerval Zanella Netto <azanella at linux dot vnet.ibm.com> 2012-05-06 14:43:27 UTC ---
Commit '31dc8730af585d8e13021484752fb20decae0661' fixes this and also the same
issue for acosl. My patch corrects the case for value near '1' that depends on
both double and also for every comparison using the wrong absolute value for
'x'.

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[Bug math/13563] LoP asinl returns unexpected value on long double

[azanella at linux dot vnet.ibm.com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13563

Adhemerval Zanella Netto <azanella at linux dot vnet.ibm.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |RESOLVED
         Resolution|                            |FIXED

--- Comment #7 from Adhemerval Zanella Netto <azanella at linux dot vnet.ibm.com> 2012-05-06 14:44:30 UTC ---
Fixed by commit '31dc8730af585d8e13021484752fb20decae0661'.

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[Bug math/13563] LoP asinl returns unexpected value on long double

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=13563

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
              Flags|                            |security-

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