[PATCH] D83468: [Debuginfo] Fix for PR46653

Wed Aug 19 10:11:20 PDT 2020

aemerson added a comment.

In D83468#2226466 <https://reviews.llvm.org/D83468#2226466>, @Jac1494 wrote:

>> I would consider this to be more of a bug in GDB. Line 0 has a well-defined meaning in DWARF and stands for "no source location corresponds to this code". LLDB, for example, interprets line 0 as an indicator to skip over instructions and automatically steps over them when single-stepping through a program, since line 0 is not a meaningful place to stop. It might be worth talking to the GDB developers and ask them what they think about adding a similar feature to their handling of line 0. DWARF doesn't prescribe that that's how debuggers should behave, but I think it's a reasonable interpretation.
>
> @aprantl I understand line zero meaning in DWARF standard. 
> But could you please explain that why this behavior is there with only with Global-isel enabled and NOT with SelectionDAG/FastIsel...? 
> I mean when selection/fast-isel is enabled this not seen when using GDB. That suggest bug in global-isel not in GDB...?

GlobalISel is a different instruction selection framework to SelectionDAG. Therefore, it can make different decisions and generate different code. That does not necessarily imply that there's a bug in GlobalISel, it may just be exposing an existing issue.

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  https://reviews.llvm.org/D83468/new/

https://reviews.llvm.org/D83468