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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