Re: A bug in gnat/gcc 3.3.3?

[Ludovic Brenta <ludovic.brenta@insalien.org>]

"Adrian Hoe" writes:
> Florian Weimer wrote:
>> * Ludovic Brenta:
>>
>> >> Yes! 3.4 is currently the best option. 3.15 is old, 3.3 is buggy
> and
>> >> 4.0 is still fighting with the tree-saa extentsion.
>> >
>> > I differ with this.  The quality of GCC 3.4 is similar to, but not
>> > significantly better than that of GNAT 3.15p.  Also, 3.4 is much
>> > slower and memory-hungry than 3.15p (it may or may not matter to
> you
>> > but it's a fact).
>>
>> But this comparison is not fair because you are backporting fixes to
>> GNAT 3.15p.  No one is doing this for GNAT in GCC 3.4. 8-)
>>
>> Due to the NPTL problem, plain GNAT 3.15p is probably not so useful
>> for many people with recent GNU/Linux distributions.
>
> Could you elaborate further your last statement? Why do you think
> gnat3.15p is not so useful with recent GNU/Linux distribution?

This issue has been discussed at length here.  It is summarised in the
corresponding Debian bug report:

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=245312

The workaround is to declare the environment variable
LD_ASSUME_KERNEL=2.4.1

or any other value less than 2.6.  The problem is on linux >= 2.6 with
glibc >= 2.3, and on some 2.4 kernels provided by Red Hat.  The patch
that fixes this problem in GNAT 3.15p is quite small.

> Also, does gnat3.15p work well with gcc3.3.3?
>
> If I'm going to bootstrap gnat 3.15p with gnat/gcc3.3.3, wouldn't the
> buggy 3.x affect the compilation? Has anyone tried to bootstrap
> gnat3.15p with gnat/gcc3.x before?

I have done that without problems.  The bootstrapping has three
stages; the bootstrap compiler is used only in the first stage, to
build a non-optimised new compiler.  Then the new compiler recompiles
itself, with optimisations, two times (stages 2 and 3) and compares
the output.  If the two recompiles gave the same results, the
bootstrap is considered successful.

-- 
Ludovic Brenta.


This patch makes it possible to use the New POSIX Thread Library on
Linux >= 2.6 and glibc >= 2.3.  It also works on linux 2.4.  I
backported it from GCC 3.4.

I omitted irrelevant parts of this patch to keep it minimal.

-- 
Ludovic Brenta.