[llvm-commits] patch for Bug #10125

[Jakob Stoklund Olesen]

On Jun 12, 2011, at 12:50 AM, Shajrawi, Yousef wrote:

> I’ve reported bug #10125 about debug variables incorrectly deleted by LLVM in the Live Debug Variables pass: http://llvm.org/bugs/show_bug.cgi?id=10125
>  
> Attached is a patch resolving this bug via adding a check to live ins of a basic block (description is in bugzilla)

Hi Yousef,

I think you are misunderstanding the purpose of the Live Debug Variables pass. It is supposed to remove all DBG_VALUE instructions. It builds a data structure that is easier to work with for the register allocator passes.

After register allocation, the DBG_VALUE instructions are written back with references to the correct physical registers and spill slots.

This is all necessary to keep track of debug variables while the register allocator coalesces and splits and spills live ranges.

>  Please see if this is suitable for adding to LLVM and/or please advise on what to do next, This is my first contribution to LLVM so I don’t know the procedure…

You are on the right track, but please make sure that you describe the actual symptoms when you file a bug report. The behavior you describe sounds correct to me, and when I run your IR through the ARM backend, the result looks fine.

So what caused you to file a bug in the first place?

/jakob

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