[Dwarf-Discuss] Location list entries for caller-saved registers at time of call
david.stenberg at ericsson.com
Thu Dec 6 07:49:56 PST 2018
On tor, 2018-12-06 at 16:32 +0100, Andreas Arnez via Dwarf-Discuss
> If GDB uses caller-saved register values from the inner-most frame in
> outer frames, then this is a bug. Note that this could also be
> by bad CFI.
Hmm, right. I'm not very familiar with the design philosophy of GDB,
but as far as I have understood it they prefer to rely on producer to
emit such information. In the LLVM bug report  I wrote for this I
mentioned using DW_CFA_undefined for caller-saved registers, or at
least for those that it knows are clobbered.
Neither GCC nor Clang emits CFI for caller-saved registers at the
moment. I have not been successful in finding out why, but my
(uneducated) guess is that, maybe at least one of the reasons, is
debug info size concerns?
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