[LLVMdev] Unwind behaviour in Clang/LLVM

[Jim Grosbach]

On Feb 7, 2014, at 3:35 AM, Renato Golin <renato.golin at linaro.org> wrote:

> On 7 February 2014 09:35, Renato Golin <renato.golin at linaro.org> wrote:
> Do we have such logic in Clang at the moment?
> 
> Let me answer my own question. Right now, both -funwind-tables and -fno-unwind-tables only enable the -muniwind-tables for -cc1, and either lack or presence of that flag in -cc1 has the same behaviour on C++ code: they both generate .eh_frame sections.
> 
> The only behaviour I found is that -munwind-tables will add uwtable to functions, which had no effect on x86_64. Is that because x86_64 mandates unwind tables?
> 
> If the semantics is that uwtable turns on tables on targets that don't require it (SjLj), but not that it turns off if missing on targets that mandate it, I can't use it to disable them on ARM. To be honest, recently, I'm not even sure I need, or want to disable. 
> 
> With Keith's patch to generate Dwarf unwind, the -arm-disable-ehabi flag could possibly be removed clean, and we can go directly to step 2.
> 
> Keith, Reid, are you happy with always generating unwind tables on ARM regardless?

Just to double check, none of this will change the current behavior on Darwin, right?

-Jim

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