Re: DWARF2 FDE Address Mismatch

Daniel Jacobowitz
2007-06-01T17:14:58Z

On Fri, Jun 01, 2007 at 03:26:13PM +0100, Matt Kern wrote:
> On Fri, Jun 01, 2007 at 09:43:55AM -0400, Daniel Jacobowitz wrote:
> > On Fri, Jun 01, 2007 at 01:20:49PM +0100, Matt Kern wrote:
> > > ...
> > > In short it looks like GDB DWARF2 support lacks a mechanism to override
> > > the address size (comparable to DWARF2_ADDR_SIZE in gcc). Is my
> > > understanding correct?
> >
> > Yes, that looks true. Perhaps it should be using TARGET_ADDR_BIT
> > instead.
>
> A quick look at GCC tells me:
>
> * For EH data it uses a potentially arch-specific macro,
> ASM_PREFERRED_EH_DATA_FORMAT() to determine the address siz. This
> macro is parameterised by code (data, code label, function ptr) and
> global (true if may be affected by dynamic relocs).
>
> * For non-EH data, DWARF2_ADDR_SIZE is used.

For .eh_frame we have to do this funny dance with GCC to determine the
"right" behavior. For .debug_frame, there is a standard and we should
be following it - and so should GCC. What does it have to say? If it
says "the size of an address on the target machine" then we should
probably use TARGET_ADDR_BIT; otherwise I'm not sure. I think this
format ambiguity has come up before.

--
Daniel Jacobowitz
CodeSourcery