llvm dev - Nov 2016 - getting the value back from metadata

Hello,

I'm trying to extract the value out of my MDNode, but for some reason I
can't.



For example, if one part of the code gets an MDNode that was created as follows:

Metadata* vals[2] 
       { ValueAsMetadata::get(&F),
ValueAsMetadata::get(ConstantInt::get(context, 135)) };

MDNode* mdnode = MDNode::get(context, vals);



Is it possible to extract the value of the constant int (135 in this case)?



I tried using MetaDataAsValue as follows:

cast<ConstantInt>(MetadataAsValue::get(context,

                                 mdnode->getOperand(1)))->getZExtValue()



but I get NULL... (although when pronting the MetadataAsValue I do see "i32
135")



maybe the MDNode should be built in a different manner?



Thanks!

Alon





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> On Nov 14, 2016, at 9:18 AM, Alon Shaltiel (ashaltie) via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> 
> Hello,
> I’m trying to extract the value out of my MDNode, but for some reason I
can’t.
>  
> For example, if one part of the code gets an MDNode that was created as
follows:
> Metadata* vals[2] >        { ValueAsMetadata::get(&F),
ValueAsMetadata::get(ConstantInt::get(context, 135)) };
> MDNode* mdnode = MDNode::get(context, vals);
>  
> Is it possible to extract the value of the constant int (135 in this case)?
>  
> I tried using MetaDataAsValue as follows:
> cast<ConstantInt>(MetadataAsValue::get(context,
>                                 
mdnode->getOperand(1)))->getZExtValue()
>  
You should try mdconst::extract<ConstantInt> instead of
cast<ConstantInt> (search in the codebase for example if needed).

— 
Mehdi

> 
> 
> 
> but I get NULL… (although when pronting the MetadataAsValue I do see “i32
135”)
>  
> maybe the MDNode should be built in a different manner?
>  
> Thanks!
> Alon
>  
>  
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>
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Thanks a lot! J



From: mehdi.amini at apple.com [mailto:mehdi.amini at apple.com]
Sent: Monday, November 14, 2016 9:07 PM
To: Alon Shaltiel (ashaltie)
Cc: llvm-dev at lists.llvm.org
Subject: Re: [llvm-dev] getting the value back from metadata





   On Nov 14, 2016, at 9:18 AM, Alon Shaltiel (ashaltie) via llvm-dev
<llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>>
wrote:



   Hello,

   I’m trying to extract the value out of my MDNode, but for some reason I
can’t.



   For example, if one part of the code gets an MDNode that was created as
follows:

   Metadata* vals[2] 
          { ValueAsMetadata::get(&F),
ValueAsMetadata::get(ConstantInt::get(context, 135)) };

   MDNode* mdnode = MDNode::get(context, vals);



Is it possible to extract the value of the constant int (135 in this case)?



I tried using MetaDataAsValue as follows:

cast<ConstantInt>(MetadataAsValue::get(context,

                                 mdnode->getOperand(1)))->getZExtValue()





You should try mdconst::extract<ConstantInt> instead of
cast<ConstantInt> (search in the codebase for example if needed).



—

Mehdi

















but I get NULL… (although when pronting the MetadataAsValue I do see “i32 135”)



maybe the MDNode should be built in a different manner?



Thanks!

Alon





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