Re: [libiberty and gdb] floatformat_is_valid

[Andrew Cagney <ac131313@redhat.com>]

> On Mon, Sep 15, 2003 at 10:39:33AM -0400, Daniel Jacobowitz wrote:
> 
>> GDB's "struct value" has a union in it.  This union, named "aligner", has a
>> long double member as well as several others; its goal is to be a cheap way
>> to ensure that we can load all sorts of values straight from the value
>> structure, without alignment problems.  Unfortunately, this means that when
>> debugging GDB we tend to feed random bytes to printf ("%.35Lg").  That's not
>> kosher, and on i386 I've found a whole bunch of numbers which can crash it -
>> the gist is that GMP shifts normalized numbers over until it hits a one bit,
>> and if the explicit integer bit isn't set it walks right out of the number.
>> 
>> This could show up in other places too.  Anywhere you print floating-point
>> data from the inferior, really.
>> 
>> So here's a patch which checks for the problem.  I added
>> floatformat_is_valid to libiberty/floatformat.c.  Is this OK?
>> [Do I need approval?  Floatformat.c is in libiberty, but marked as part of
>> GDB.]
>> 
>> Oh, this patch misses some copyright year updates.  I'll get them before
>> checking in.
> 
> 
> This patch fixes a really annoyin problem when debugging GDB.  It
> doesn't generally come up debugging anything else, though.

For the record, I don't care :-)  It appears to work (I guess my 
revision should go in?), and fixes a bug.

> I'm planning to leave the patch for 6.0.1.  Does anyone believe it
> should be in 6.0 instead?

enjoy,
Andrew