[Bug math/16414] New: IBM long double truncl assembly implementation showing wrong results

[Bug math/16414] New: IBM long double truncl assembly implementation showing wrong results

[azanella at linux dot vnet.ibm.com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16414

            Bug ID: 16414
           Summary: IBM long double truncl assembly implementation showing
                    wrong results
           Product: glibc
           Version: 2.19
            Status: NEW
          Severity: normal
          Priority: P2
         Component: math
          Assignee: unassigned at sourceware dot org
          Reporter: azanella at linux dot vnet.ibm.com

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[Bug math/16414] IBM long double truncl assembly implementation showing wrong results

[azanella at linux dot vnet.ibm.com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16414

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED

--- Comment #1 from Adhemerval Zanella Netto <azanella at linux dot vnet.ibm.com> ---
While seeking why some tgammal results shows wrong signal on PPC64, I found
out that the assembly implementation truncl
(sysdeps/powerpc/powerpc64/fpu/s_truncl.S)
for is in fact returning wrong results for some inputs. More specifically,
for number where the first double is a exact integer and the precision
is determined by second long double.

Checking on implementation comments and history, I am very confident the
assembly implementation was based on a version before commit
5c68d401698a58cf7da150d9cce769fa6679ba5f that fixes BZ#2423 (Errors in
long double (ldbl-128ibm) rounding functions in glibc-2.4), since
the implementation indeed does not handle some inputs correctly.

A possible solutions is just remove the implementation and make the build
select 
sysdeps/ieee754/ldbl-128ibm/s_truncl.c instead (which contains all the
appropriated fixes).

(Hit enter button before finishing editing, this comments is the bug
description).

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[Bug math/16414] IBM long double truncl assembly implementation showing wrong results

[azanella at linux dot vnet.ibm.com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16414

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |azanella at linux dot vnet.ibm.com
           Assignee|unassigned at sourceware dot org   |azanella at linux dot vnet.ibm.com

--- Comment #2 from Adhemerval Zanella Netto <azanella at linux dot vnet.ibm.com> ---
The patch https://sourceware.org/ml/libc-alpha/2014-01/msg00136.html fixes this
issue.

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[Bug math/16414] IBM long double truncl assembly implementation showing wrong results

[azanella at linux dot vnet.ibm.com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16414

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

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

--- Comment #3 from Adhemerval Zanella Netto <azanella at linux dot vnet.ibm.com> ---
Fixed by commit 38f3458175ecf7c3588bd5b6e465f4d9205fbe1c.

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[Bug math/16414] IBM long double truncl assembly implementation showing wrong results

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16414

Florian Weimer <fweimer at redhat dot com> changed:

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

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