[cfe-dev] [LLVMdev] Unwind behaviour in Clang/LLVM

[Renato Golin]

Hi Joerg,

You are right, there are three separate issues here: unwinding, debug info
and exception handling.

Debug and EH require unwinding, but one doesn't require the other and
unwinding is not exclusive to either.


On 6 February 2014 14:51, Joerg Sonnenberger <joerg at britannica.bec.de>wrote:

> (1) Should enough unwind data be provided for a basic, read-only stack
> walk?
>

As you said, platforms and systems should define their own defaults, and
that's mainly driven by the front-end via flags and triples.

The behaviour of flags should be precise, and different flags should be
on/off by default depending on the triple, so build systems can enforce
flags if they need to make sure the behaviour will be the same across
different platforms.

I can't decide that, but those decisions should stay in the front-end. To
the back-end, function attributes should be able to control table emission
(or maybe we need flags, I don't know).



> That said, the option already exists for changing the default:
> -funwind-tables. There shouldn't be another ARM specific flag.
>

So, can I assume that -f{no-}unwind-tables's syntax is to completely
enable/disable the unwind tables and add/remove the ELF sections from the
objects? If that's so, I can easily remove -arm-disable-ehabi and check on
that flag.

thanks,
--renato
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