Re: [PATCH][BZ #6803] Set errno for scalbln, scalbn

[Stefan Liebler <stli at linux dot vnet dot ibm dot com>]

Hi,

this patch introduces a new wrapper for scalbln functions
in order to set errno to ERANGE on overflow and underflow.
The existing aliases that uses __scalbln functions are replaced by 
aliases to the new wrapper.
The corresponding tests in libm-test.inc are updated to check for errno 
via ERRNO_PLUS_OFLOW etc.

This patch only covers the scalbln-part of bug 6803.

Tested on s390/s390x/x86_64/ppc64.
Please review and test and give feedback, if this is the way to add a 
new wrapper!

Bye.

---
2014-05-07  Stefan Liebler  <stli@linux.vnet.ibm.com>

	[BZ #6803]
	* math/libm-test.inc (scalbln_test_date):
	Add errno expectations.
	* math/w_scalblnf.c: New File.
	Add wrapper which checks for setting errno to ERANGE.
	Add weak_alias for corresponding scalbln function.
	* math/w_scalbln.c: Likewise.
	* math/w_scalblnl.c: Likewise.
	* math/Makefile (libm-calls): Add w_scalbln.
	* sysdeps/ieee754/flt-32/s_scalblnf.c:
	Remove weak_alias for corresponding scalbln function.
	* sysdeps/ieee754/dbl-64/s_scalbln.c: Likewise.
	* sysdeps/ieee754/dbl-64/wordsize-64/s_scalbln.c: Likewise.
	* sysdeps/ieee754/ldbl-96/s_scalblnl.c: Likewise.
	* sysdeps/ieee754/ldbl-128/s_scalblnl.c: Likewise.
	* sysdeps/sparc/sparc64/soft-fp/s_scalblnl.c: Likewise.
	* sysdeps/ieee754/ldbl-64-128/s_scalblnl.c:
	Remove long_double_symbol for scalblnl function in libm, libc.
	* sysdeps/ieee754/ldbl-64-128/w_scalblnl.c: New File.
	Add wrapper which checks for setting errno to ERANGE.
	Add long_double_symbol for scalblnl function in libm, libc.
	* sysdeps/ieee754/ldbl-128ibm/s_scalblnl.c:
	Remove long_double_symbol for scalblnl in libm.
	* sysdeps/ieee754/ldbl-128ibm/w_scalblnl.c: New File.
	Add wrapper which checks for setting errno to ERANGE.
	Add long_double_symbol for scalblnl function in libm.
	* sysdeps/i386/fpu/w_scalblnf.c: New File.
	Do not use wrapper because scalbn functions are used as scalbln.
	* sysdeps/i386/fpu/w_scalbln.c: Likewise.
	* sysdeps/i386/fpu/w_scalblnl.c: Likewise.
	* sysdeps/m68k/m680x0/fpu/w_scalblnf.c: Likewise.
	* sysdeps/m68k/m680x0/fpu/w_scalbln.c: Likewise.
	* sysdeps/m68k/m680x0/fpu/w_scalblnl.c: Likewise.
	* sysdeps/ia64/fpu/w_scalblnf.c: New File.
	Do not use wrapper because of own implementation.
	* sysdeps/ia64/fpu/w_scalbln.c: Likewise.
	* sysdeps/ia64/fpu/w_scalblnl.c: Likewise.
---

On 04/25/2014 04:35 PM, Joseph S. Myers wrote:
> On Wed, 23 Apr 2014, Stefan Liebler wrote:
>
> > Hi,
> >
> > this patch sets errno to ERANGE on overflow and underflow.
> > The corresponding tests in libm-test.inc are updated to check for errno, too.
> >
> > Tested on S390/S390x.
> >
> > ok to commit?
>
> I don't think this is the best approach.  Apart from needing lots of
> architecture-specific versions updated (so you'd need to draw the
> attention of relevant architecture maintainers to the issue), we already
> have a scalbn wrapper that checks for overflow/underflow and sets errno,
> in the form of ldexp.  So for scalbn it would be most natural to make
> scalbn an alias for __ldexp instead of __scalbn; for scalbln you'd need to
> add a new wrapper, replacing scalbln being an alias for __scalbln.
>
> (The tests will then need to use ERRNO_PLUS_OFLOW etc. so the expectations
> only cover the cases where glibc guarantees errno setting.)

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