[git commit] libubacktrace: use -funwind-tables rather than -fexecptions

[Mike Frysinger]

On Tuesday 03 January 2012 11:34:40 Carmelo AMOROSO wrote:
> On 01/01/2012 0.10, Mike Frysinger wrote:
> > On Thursday 22 December 2011 13:19:22 Carmelo AMOROSO wrote:
> >> On 22/12/2011 15.30, Carmelo Amoroso wrote:
> >>> For backtrace to work is enough to use -funwind-tables instead
> >>> of -fexceptions.
> >> 
> >> Indeed, I'm wondering if -fasynchrous-unwind-tables should be
> >> used rather then funwind-tables. On my arh SH4 the generated code
> >> is exactly the same. I'm not expert of DWARF, neither gcc
> >> documentation regarding the differences between -fexceptions,
> >> -funwind-tables or -fasynchronous-unwind-tables helped me so
> >> much.
> >> 
> >> someone else has clearer idea ?
> > 
> > for backtrace, we just want unwind-tables, so using that over
> > -fexceptions is good (since we don't have to handle exceptions in
> > this code).  as for the async vs non-async unwind-tables, i don't
> > know the answer to that.
> 
> I've reported here below the extract from gcc manual. Reading it
> again, it seems to me that using -fasynchronous-unwind-tables is the
> best as it's purpose is actually to create the dwarf2 information, in
> the other two cases (-fexceptions or -funwind-tables) it seems to be a
> side effect.

glibc seems to prefer -fasynchronous-unwind-tables, so that's probably good 
for us too

we need -fexceptions if the funcs themselves need to handle exceptions.  but 
if we only want other things to be able to build a backtrace across the call, 
then -fasynchronous-unwind-tables should be sufficient.
-mike
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