tberghammer added inline comments.
================
Comment at:
source/Plugins/UnwindAssembly/x86/x86AssemblyInspectionEngine.cpp:875-876
+ row->GetCFAValue().GetRegisterNumber() == m_lldb_fp_regnum) {
+ current_sp_bytes_offset_from_cfa =
+ row->GetCFAValue().GetOffset() - stack_offset;
+ }
----------------
labath wrote:
> tberghammer wrote:
> > Shouldn't you change the unwind information for the CFA here? For me saying
> > CFA=rbp seems like an incorrect thing to do, but not sure what would be the
> > correct value (Undefined? IsSame?). The impact is if an other register (or
> > a local variable) have a location specified as CFA+off then after this
> > instruction it will point to bogus location.
> I think there has been some misunderstanding, as the your comment makes no
> sense to me. :)
>
> This code only fires if CFA=rbp+offset, and that remains valid even after
> this instruction -- `lea` does not change the value of the rbp register, so
> any register rule that was valid before this instruction will remain valid
> after it. This only begins to make a difference after we process the `pop
> %rbp` instruction -- then we will update the CFA rule to read
> `CFA=rsp+current_sp_bytes_offset_from_cfa`.
You are right, please ignore my comment. I somehow assumed the `lea`
instruction will change the value of `rbp` as well not just `rsp`.
https://reviews.llvm.org/D34750
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