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

Hi,

I have a problem that dbg_value nodes are not transferred when integer DAG nodes
are promoted. For example, an i32 add node is promoted to a i64 add node by
DAGTypeLegalizer::PromoteIntegerResult and its dbg_value node is not transferred
to the new node.

t9: i32 = add nsw t5, t8 -->  t31: i64 = add t30, t7   ; the dbg_value node
is not transferred to the new i64 add node.

For expansion, DAGTypeLegalizer::SetExpandedInteger calls transferDbgValues()
but I couldn't find any place to call trasnferDbgValues() for integer type
promotion in DAGTypeLegalizer ::SetPromotedInteger and other places. I am
wondering If I miss anything or the legalization needs to call
transferDbgValues() for this case.

I found this problem because a recently added unittest,
DebugInfo/X86/linear-dbg-value.ll fails for my project, and the x86 and aarch64
backends don't have this problem since they don't promote i32 add nodes.

Thanks,
Sejong

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+ Adrian, Joshua
+ Jonas, since he contributed the transferDbgValues change in
DAGTypeLegalizer::SetExpandedInteger
> On Mar 8, 2018, at 5:44 PM, Se Jong Oh via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> Hi,
>  
> I have a problem that dbg_value nodes are not transferred when integer DAG
nodes are promoted. For example, an i32 add node is promoted to a i64 add node
by DAGTypeLegalizer::PromoteIntegerResult and its dbg_value node is not
transferred to the new node.
>  
> t9: i32 = add nsw t5, t8 à  t31: i64 = add t30, t7   ; the dbg_value node
is not transferred to the new i64 add node.
>  
> For expansion, DAGTypeLegalizer::SetExpandedInteger calls
transferDbgValues() but I couldn’t find any place to call trasnferDbgValues()
for integer type promotion in DAGTypeLegalizer ::SetPromotedInteger and other
places.
Maybe the right place to do this is within the PromoteIntRes_ helper for sign
extensions?

best,
vedant
> I am wondering If I miss anything or the legalization needs to call
transferDbgValues() for this case.
>  
> I found this problem because a recently added unittest,
DebugInfo/X86/linear-dbg-value.ll fails for my project, and the x86 and aarch64
backends don’t have this problem since they don’t promote i32 add nodes.
>  
> Thanks,
> Sejong
>  
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> llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>
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Thanks for help! I think that sign extension is not involved here.
PromoteIntegerResult is called since i32 is not a legal type in my target and
the legalizer promotes operations with i32 result type to i64 operations. I
think that SetPromotedInteger seems to be a common place for all promotions like
SetExpandedInteger.

Jonas, I would appreciate it if you can guide me about whether my understanding
is correct or not.

Thanks,
Sejong



From: vsk at apple.com <vsk at apple.com>
Sent: Friday, March 9, 2018 3:19 PM
To: Se Jong Oh <sejooh at microsoft.com>
Cc: llvm-dev at lists.llvm.org; Jonas Devlieghere <jdevlieghere at
apple.com>; Adrian Prantl <aprantl at apple.com>; pidgeot18 at
gmail.com
Subject: Re: [llvm-dev] [SelectionDAG] DbgValue nodes aren't transferred

+ Adrian, Joshua
+ Jonas, since he contributed the transferDbgValues change in
DAGTypeLegalizer::SetExpandedInteger

On Mar 8, 2018, at 5:44 PM, Se Jong Oh via llvm-dev <llvm-dev at
lists.llvm.org<mailto:llvm-dev at lists.llvm.org>> wrote:

Hi,

I have a problem that dbg_value nodes are not transferred when integer DAG nodes
are promoted. For example, an i32 add node is promoted to a i64 add node by
DAGTypeLegalizer::PromoteIntegerResult and its dbg_value node is not transferred
to the new node.

t9: i32 = add nsw t5, t8 -->  t31: i64 = add t30, t7   ; the dbg_value node
is not transferred to the new i64 add node.

For expansion, DAGTypeLegalizer::SetExpandedInteger calls transferDbgValues()
but I couldn’t find any place to call trasnferDbgValues() for integer type
promotion in DAGTypeLegalizer ::SetPromotedInteger and other places.

Maybe the right place to do this is within the PromoteIntRes_ helper for sign
extensions?

best,
vedant


I am wondering If I miss anything or the legalization needs to call
transferDbgValues() for this case.

I found this problem because a recently added unittest,
DebugInfo/X86/linear-dbg-value.ll fails for my project, and the x86 and aarch64
backends don’t have this problem since they don’t promote i32 add nodes.

Thanks,
Sejong

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