[RFA/RFC/dwarf] detect 0xffffffff size attribute values

[Joel Brobecker <brobecker at adacore dot com>]

Hello,

This an attempt to guard against a compiler bug:

    http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35998

I know that Olivier and Eric told me that they committed some changes
in gigi that should fix some of the problems, but I don't know if this
one is already fixed on not. If someone does a build from HEAD could
tell me, that'd be great.

In any case, to help handling older versions of the compiler,
I propose we install a guard against -1 size attributes, which
get encoded as 0xffffffff.  When we detect this size attribute
value, we pretend we actually read 0.  This avoids attempting
to make a huge memory allocation when trying to create a value
of the associated type.

Jan, could you check whether this fixes the problem you saw?

2008-06-19  Joel Brobecker  <brobecker@adacore.com>

        * dwarf2read.c (read_attribute_value): Treat size attribute
        values of 0xffffffff as if the attribute value was zero.

Tested on x86-linux (both the standard regression testsuite and
the AdaCore regression testsuite). No regression.

What do you think? I know Daniel said during one of our conversations
that the idea itself is reasonable, but does the implementation look
OK to you?

Thanks,
-- 
Joel

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