[lldb-dev] Inquiry regarding AddOneMoreFrame function in UnWindLLDB

via lldb-dev lldb-dev at lists.llvm.org
Tue May 31 11:31:41 PDT 2016

> On May 31, 2016, at 12:52 AM, Ravitheja Addepally via lldb-dev <lldb-dev at lists.llvm.org> wrote:
> Hello,
>       I posted this query a while ago, i still have no answers, I am currently working on Bug 27687 (PrintStackTraces), so the reason for the failure is the erroneous unwinding of the frames from the zeroth frame. The error is not detected in AddOneMoreFrame, since it only checks for 2 more frames, if it was checking more frames in AddOneMoreFrame, it would have detected the error. Now my questions are ->
> ->  is that is there any specific reason for only checking 2 frames instead of more ?

The stepping machinery uses the unwinder on each stop to figure out whether it has stepped in or out, which is fairly performance sensitive, so we don't want AddOneMoreFrame to do more work than it has to.  


> ->  Why no make the EH CFI based unwinder the default one and make the assembly the fallback ?
> Best Regards,
> A Ravi Theja
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