[LLVMdev] creating new Metadata

[John Criswell]

On 12/21/11 11:24 PM, Oksana Tkachuk wrote:
> Hello,
> Thank you very much for the pointers.
> I am are able to create new MDNodes, filled with some constants, and 
> attach them
> to llvm instructions. However, the metadata map is not getting updated 
> as expected.
> For example, instead of the expected new entry

If you look at PoolMDPass::runOnModule(), you'll see that the MDNodes 
are stored in a container (ValueToPoolNodes) and that they are added as 
operands to a NamedMDNode.  I think you have to make your MDNodes 
operands of a NamedMDNode in order to get them to work properly.

-- John T.

>
> !n = metadata !{some values}
>
> we are getting
>
> !n = metadata !{null}
>
> Do you know what might be wrong? Do we need to enter the MDNodes into 
> the map explicitly?
>
> Thank you,
> Oksana
>
>
> On Tue, Dec 20, 2011 at 7:25 PM, ??? <chenwj at iis.sinica.edu.tw 
> <mailto:chenwj at iis.sinica.edu.tw>> wrote:
>
>     > Dear llvm-ers,
>     > I am trying to attach a customized metadata to llvm instructions.
>     > Let's say, I want to attach some number to each instruction.
>     > I am trying to use
>     >
>     > void Instruction::setMetadata(unsigned KindID, MDNode* Node)
>     >
>     > but I am not sure how to create a brand new instance of an MDNode.
>     > Do you have any code samples demonstrating how to do that?
>     >
>     > Due to some tool dependencies, I am using LLVM 2.7
>
>      `grep -r MDNode` in $LLVM_SOURCE may give you some examples.  I
>     don't know if
>     there is a doxygen for LLVM 2.7, but you can see
>     include/llvm/Metadata.h and
>     unittests/VMCore/MetadataTest.cpp to know how to create a MDNode.
>     Below is code
>     snipt taken form MetadataTest.cpp.
>
>     ---
>      MDString *s1 = MDString::get(Context, StringRef(&x[0], 3));
>      MDString *s2 = MDString::get(Context, StringRef(&y[0], 3));
>      ConstantInt *CI = ConstantInt::get(getGlobalContext(), APInt(8, 0));
>
>      std::vector<Value *> V;
>      V.push_back(s1);
>      V.push_back(CI);
>      V.push_back(s2);
>
>      MDNode *n1 = MDNode::get(Context, &V[0], 3);
>     ---
>
>     HTH,
>     chenwj
>
>     --
>     Wei-Ren Chen (???)
>     Computer Systems Lab, Institute of Information Science,
>     Academia Sinica, Taiwan (R.O.C.)
>     Tel:886-2-2788-3799 #1667
>     Homepage: http://people.cs.nctu.edu.tw/~chenwj
>     <http://people.cs.nctu.edu.tw/%7Echenwj>
>
>
>
>
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