llvm dev - Apr 2018 - [SelectionDAG] DbgValue nodes aren't transferred

> On Apr 30, 2018, at 2:57 PM, Se Jong Oh <sejooh at microsoft.com>
wrote:
> 
> Thanks! It looks like SelectionDAG::salvageDebugInfo handles only addition
with constant.
You can look at llvm::salvageDebugInfo() for examples on how to handle other
situations.

-- adrian

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For cast instructions, llvm::salvageDebugInfo() simply makes dbg.value point to
the source of the cast. Since SelectionDAG already has transferDbgValues which
can move dbgvalue to the cast source, I think that we can just call it where the
truncate is optimized away.

Thanks,
Sejong

From: aprantl at apple.com <aprantl at apple.com>
Sent: Monday, April 30, 2018 2:59 PM
To: Se Jong Oh <sejooh at microsoft.com>
Cc: jdevlieghere at apple.com; Vedant Kumar <vsk at apple.com>; llvm-dev
at lists.llvm.org; pidgeot18 at gmail.com
Subject: Re: [llvm-dev] [SelectionDAG] DbgValue nodes aren't transferred




On Apr 30, 2018, at 2:57 PM, Se Jong Oh <sejooh at
microsoft.com<mailto:sejooh at microsoft.com>> wrote:

Thanks! It looks like SelectionDAG::salvageDebugInfo handles only addition with
constant.

You can look at llvm::salvageDebugInfo() for examples on how to handle other
situations.

-- adrian

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> On Apr 30, 2018, at 3:16 PM, Se Jong Oh <sejooh at microsoft.com>
wrote:
> 
> For cast instructions, llvm::salvageDebugInfo() simply makes dbg.value
point to the source of the cast. Since SelectionDAG already has
transferDbgValues which can move dbgvalue to the cast source, I think that we
can just call it where the truncate is optimized away.
That sounds reasonable, yes. Casts are effectively transparent for debug info
purposes.

-- adrian
>  
> Thanks,
> Sejong
>  
> From: aprantl at apple.com <mailto:aprantl at apple.com> <aprantl
at apple.com <mailto:aprantl at apple.com>>
> Sent: Monday, April 30, 2018 2:59 PM
> To: Se Jong Oh <sejooh at microsoft.com <mailto:sejooh at
microsoft.com>>
> Cc: jdevlieghere at apple.com <mailto:jdevlieghere at apple.com>;
Vedant Kumar <vsk at apple.com <mailto:vsk at apple.com>>; llvm-dev
at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>; pidgeot18 at
gmail.com <mailto:pidgeot18 at gmail.com>
> Subject: Re: [llvm-dev] [SelectionDAG] DbgValue nodes aren't
transferred
>  
>  
> 
> 
> On Apr 30, 2018, at 2:57 PM, Se Jong Oh <sejooh at microsoft.com
<mailto:sejooh at microsoft.com>> wrote:
>  
> Thanks! It looks like SelectionDAG::salvageDebugInfo handles only addition
with constant.
>  
> You can look at llvm::salvageDebugInfo() for examples on how to handle
other situations.
>  
> -- adrian
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