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Re: DWARF2 FDE Address Mismatch

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.

Given that decode_frame_entry_1() has to work with EH and non-EH data, I
would suggest passing eh_frame_p down into read_encoded_value() together
with an analogue for "code".  If we go on to implement EH, then we will
require a target macro that parallels ASM_PREFERRED_EH_DATA_FORMAT().
As far as I can see, this hasn't been an issue until now because most
ports either have types that are void* in size or they don't use DWARF2.

I can do the work.  How do you want to handle the patch though?  Do you
want me to submit something now, or should I hold it in our port until
it matures enough for adoption?


Matt Kern

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