Re: [libiberty and gdb] floatformat_is_valid

[Daniel Jacobowitz <drow@mvista.com>]

On Thu, Sep 18, 2003 at 06:59:37PM -0400, Andrew Cagney wrote:
> >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 asked myself, "Dan, are you going to add this patch to all your GDB
packages anyway?"  The answer was yes, so I'm checking it in.

+2003-09-19  Daniel Jacobowitz  <drow@mvista.com>
+
+       Merge from mainline:
+       2003-09-15  Daniel Jacobowitz  <drow@mvista.com>
+
+       * values.c (unpack_double): Call floatformat_is_valid.

+2003-09-15  Andrew Cagney  <cagney@redhat.com>
+
+       * floatformat.h (floatformat_to_double): Make input buffer constant.
+       (floatformat_from_double, floatformat_is_valid): Ditto.
+       
+2003-09-15  Daniel Jacobowitz  <drow@mvista.com>
+
+       * floatformat.h (floatformat_is_valid): Add prototype.
+

+2003-09-15  Andrew Cagney  <cagney@redhat.com>
+
+       * floatformat.c (get_field): Make "data" constant.
+       (floatformat_is_valid, floatformat_to_double): Make "from"
+       constant, fix casts.
+       (floatformat_from_double): Make "from" constant.
+
+2003-09-15  Daniel Jacobowitz  <drow@mvista.com>
+
+       * floatformat.c (floatformat_is_valid): New function.
+       (get_field, put_field): Correct comments.
+

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer