Re: MPFR 2.3.1 Release Candidate

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MPFR 2.3.1 Release Candidate
\ Vincent Lefevre (29 Dec 2007)
. \ Dennis Clarke (29 Dec 2007)
. . \ Dave Korn (29 Dec 2007)
. . . \ Dennis Clarke (29 Dec 2007)
. . . \ Vincent Lefevre (29 Dec 2007)
. . . . \ Vincent Lefevre (1 Jan 2008)
. \ Kaveh R. GHAZI (31 Dec 2007)
. . \ Vincent Lefevre (1 Jan 2008)
. . . \ Kaveh R. GHAZI (2 Jan 2008)
. . . . \ Vincent Lefevre (2 Jan 2008)
. . . . . \ Kaveh R. GHAZI (4 Jan 2008)
. . . . . . \ Vincent Lefevre (4 Jan 2008)

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Subject:	Re: MPFR 2.3.1 Release Candidate
Group:	Gcc
From:	Kaveh R. GHAZI
Date:	31 Dec 2007

On Sat, 29 Dec 2007, Vincent Lefevre wrote:

> The release of MPFR 2.3.1 is imminent. Please help to make this
> release as good as possible by downloading and testing this
> release candidate:
> [...]
> Changes from version 2.3.0 to version 2.3.1:
> - Bug fixes; see <http://www.mpfr.org/mpfr-2.3.0/#bugs>.
> - Improved MPFR manual.

Hi Vincent,

I read through the bugs in 2.3.0 from the above link. I'm trying to see
if I can write a GCC testcase that exposes one of those bugs when GCC is
linked with mpfr-2.3.0, but passes when I use 2.3.1-rc1.

The bug would need to be exposed using a mantissa size of a C type, like
53 for double, and the default exponent range. And all the global mpfr
flags are cleared beforehand, and the input precision is the same as the
output precision. These circumstances seem to eliminate many (all?) of
the potential failures.

I tried several things through gcc+mpfr-2.3.0 like asin(-0.0), but that
folds to -0.0 correctly. I tried a call to sqrt(2.0) with
-frounding-math. But the inexact flag is apparently set and gcc
appropriately does not fold this case, instead replying on the library
call to get the rounding correct.

I'd rather not test for inefficiencies or infinite loops because then the
testcase will take too long to timeout and slow down everyone's testsuite
runs.

Often the bug says it will fail on "huge" inputs, but doesn't say exactly
what they are.

Rather than further guessing on my part, would you please suggest
something?

Thanks,
--Kaveh
--
Kaveh R. Ghazi ghazi