llvm dev - Mar 2011 - [LLVMdev] Accessing metadata & creating DIVariable

Hi,

I am wondering if someone can guide me in adding metadata to IR which
already contains some metadata. I am trying to add dbg.declare inst
for a local variable I added to a function. I used the DIBuilder to
build a DIVariable. When I try to compile llc fails  with following
message.

  llc: MCAsmStreamer.cpp:273: virtual
void<unnamed>::MCAsmStreamer::EmitLabel(llvm::MCSymbol*): Assertion
`Symbol->isUndefined() &&   "Cannot define a symbol
twice!"' failed.

I can't figure out what is wrong, there are no obvious duplicate
entries. The original CU entry got replaced by the CU I created  with
DIBuilder. Not sure, if changing the CU is the cause of error.

What is the right way to get a handle on the MDNode of the CompileUnit
in a Module ?

bye,
Vyas

On Mar 28, 2011, at 2:36 PM, Vedavyas Duggirala wrote:
> What is the right way to get a handle on the MDNode of the CompileUnit
> in a Module ?
> 
The CompileUnit is an instance of DICompileUnit, which is just a wrapper around
a MDNode. See DebugInfo.h
> I can't figure out what is wrong, there are no obvious duplicate
> entries. The original CU entry got replaced by the CU I created  with
> DIBuilder. Not sure, if changing the CU is the cause of error.
How did you create a CU ?
-
Devang

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>>> I am  adding local var to existing IR with debug info. I am not
using
>>> the Pass infrastructure.
>>>
>>> void InsertDbg(AllocaInst *i, StringRef varname, Instruction,
inserbefore)
>>> {
>>>
>>> DIBuilder di(*module);
>>> cu = di.createCU        / * How do I get the MDNode of  already in
the
>>> IR . Instead of recreating it, using filename and directory I knew
out
>>> of band */
>>
>> DIBuilder.createCompileUnit() does not return anything.
>>
>>> file= di.createFile
>>
>> You don't need CU here.
>>
>>>
>>> type= di.createBasicType   //long
>>
>> same, you don't need CU here.
>
> If I don't have a di.createCompileUnit.  di.createFile fails with this
message.
>
> DIBuilder.cpp:59: llvm::DIFile
> llvm::DIBuilder::createFile(llvm::StringRef, llvm::StringRef):
> Assertion `TheCU && "Unable to create DW_TAG_file_type without
> CompileUnit"' failed.
>
> Which had me scratching my head, If DIFile needs a CU it  would be an
> argument to DIBuilder::.createFile
> Also type.Verify() thought createBasicType succeeds.
I meant type.Verify() fails, though the call creatBasicType succeeds.

On Mar 29, 2011, at 8:23 AM, Vedavyas Duggirala wrote:
>>>> I am  adding local var to existing IR with debug info. I am not
using
>>>> the Pass infrastructure.
>>>> 
>>>> void InsertDbg(AllocaInst *i, StringRef varname, Instruction,
inserbefore)
>>>> {
>>>> 
>>>> DIBuilder di(*module);
>>>> cu = di.createCU        / * How do I get the MDNode of  already
in the
>>>> IR . Instead of recreating it, using filename and directory I
knew out
>>>> of band */
>>> 
>>> DIBuilder.createCompileUnit() does not return anything.
>>> 
>>>> file= di.createFile
>>> 
>>> You don't need CU here.
>>> 
>>>> 
>>>> type= di.createBasicType   //long
>>> 
>>> same, you don't need CU here.
>> 
>> If I don't have a di.createCompileUnit.  di.createFile fails with
this message.
>> 
>> DIBuilder.cpp:59: llvm::DIFile
>> llvm::DIBuilder::createFile(llvm::StringRef, llvm::StringRef):
>> Assertion `TheCU && "Unable to create DW_TAG_file_type
without
>> CompileUnit"' failed.
>> 
>> Which had me scratching my head, If DIFile needs a CU it  would be an
>> argument to DIBuilder::.createFile
>> Also type.Verify() thought createBasicType succeeds.
> 
> I meant type.Verify() fails, though the call creatBasicType succeeds.
You need to call di.createCompileUnit() once for your translation unit in the
beginning. You don't need to keep track of CU yourself. DIBuilder will take
care of it. After words, you can call di.createBasicType(..) and it will work.
-
Devang