[COMMIT] Fix decoding CIE's in DWARF frame info
Daniel Jacobowitz
drow@false.org
Fri Nov 5 20:41:00 GMT 2004
On Fri, Nov 05, 2004 at 09:36:17PM +0100, Mark Kettenis wrote:
> Date: Fri, 5 Nov 2004 14:12:17 -0500
> From: Daniel Jacobowitz <drow@false.org>
>
> On Fri, Nov 05, 2004 at 07:53:51PM +0100, Mark Kettenis wrote:
> > Date: Fri, 05 Nov 2004 12:00:12 -0500
> > From: Andrew Cagney <cagney@gnu.org>
> >
> > Mark Kettenis wrote:
> > > The old code didn't take into account that the encoding used to
> > > specify the personality routine in the augmentation could be
> > > DW_PE_EH_aligned.
> > >
> > > Fixed by the attach patch.
> > >
> > > Committed to mainline. I'll commit this to the branch later today.
> >
> > How are you testing this? I'm seeing:
> >
> > dwarf2-frame.c:1083: internal-error: Unsupported encoding: DW_EH_PE_indirect
> >
> > If your toolchain really generates DW_EH_PE_indirect, it's a different
> > problem; I don't know how to properly support this :-(.
>
> I do know that some GCC toolchains emit DW_EH_PE_indirect - I ran into
> it yesterday on PowerPC. It's exactly what it says; after applying
> whatever other encoding (pcrel, etc), dereference the result. Adding
> this to read_encoded_value should be pretty straightforward.
>
> I don't think so. We read the encoded pointers when we load the
> executable in GDB. But if the value of these encoded pointers is
> known at that point, why doesn't the (static) linker resolve things
> instead of having us goe through the indirection process?
Because this is used, as far as I know, only for PIC code in shared
libraries (which we only load after they've been dynamically
relocated). DW_EH_PE_indirect is used so that symbols which will need
a runtime RELATIVE relocation live in the data segment, instead of the
with the rest of the exception data, which could otherwise be read-only.
It's true that in general we'd have to delay the read until it was
used, but I think it'll work OK to read it right away for all cases I
know of. But I don't have a test case, so I'll just save this thought
for later.
--
Daniel Jacobowitz
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