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Re: [vta->trunk] VTA merge


On Aug 30, 2009, "Joseph S. Myers" <joseph@codesourcery.com> wrote:

> It seems likely that GDB 7.0 will be out well before GCC 4.5 and could
> be a suitable GDB version to specify.

And, in case it isn't, GDB 6.8 needs these two patches in order to deal
with code generated by the GCC trunk today, before the VTA merge:

- the patch in http://sourceware.org/bugzilla/show_bug.cgi?id=10275 for
  DW_CFA_restore_state

- http://sourceware.org/ml/gdb-patches/2009-06/msg00247.html for
  DW_LNE_set_discriminator

This means that anyone wishing to test VTA for optimized programs in the
trunk will need a GDB with these two patches for a reasonable debugging
experience.  Without them, you get broken stack traces and unrelated
line numbers.

I actually thought DW_OP_stack_value and DW_OP_implicit_value might be
somehow related with this, which is why I disabled their use for
dwarf_version < 4, but investigation showed it to be unrelated, but I'll
leave the decision on whether to retain this restriction for someone
else to make.

Both problems are fixed in the GDB trunk.  I thank Jan Kratochvil for
tracking down the two patches required to make GDB 6.8 work with GCC
trunk, before or after VTA.

-- 
Alexandre Oliva, freedom fighter    http://FSFLA.org/~lxoliva/
You must be the change you wish to see in the world. -- Gandhi
Be Free! -- http://FSFLA.org/   FSF Latin America board member
Free Software Evangelist      Red Hat Brazil Compiler Engineer


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