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Re: [PATCH] PowerPC: remove wrong truncl implementation for PowerPC64
- From: OndÅej BÃlka <neleai at seznam dot cz>
- To: Adhemerval Zanella <azanella at linux dot vnet dot ibm dot com>
- Cc: "GNU C. Library" <libc-alpha at sourceware dot org>
- Date: Wed, 8 Jan 2014 13:34:29 +0100
- Subject: Re: [PATCH] PowerPC: remove wrong truncl implementation for PowerPC64
- Authentication-results: sourceware.org; auth=none
- References: <52CC7A2A dot 3070006 at linux dot vnet dot ibm dot com> <52CC7A8F dot 6030707 at linux dot vnet dot ibm dot com> <52CD3F8E dot 1000706 at linux dot vnet dot ibm dot com>
On Wed, Jan 08, 2014 at 10:07:42AM -0200, Adhemerval Zanella wrote:
> Updated ChangeLog with bug report:
>
> ---
>
> 2014-01-08 Adhemerval Zanella <azanella@linux.vnet.ibm.com>
>
> [BZ #16414]
> * sysdeps/powerpc/powerpc64/fpu/s_truncl.S: Remove wrong
> implementation.
> * sysdeps/ieee754/ldbl-128ibm/s_truncl.c: Remove bogus comment.
>
> On 07-01-2014 20:07, Adhemerval Zanella wrote:
> > I forgot to add that I'll create a bugzilla for the truncl on PPC64 and
> > send a patch to add some test inputs for 2.20.
> >
> >
> > On 07-01-2014 20:05, Adhemerval Zanella wrote:
> >> 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.
> >>
> >> By just removing the implementation and make the build select
> >> sysdeps/ieee754/ldbl-128ibm/s_truncl.c instead it fixes the tgammal
> >> issues.
> >>
Looks ok.