[llvm-commits] [PATCH] Fix emission of debug data for global variables

[Devang Patel]

On Sep 26, 2011, at 10:20 AM, James Molloy wrote:

> Hi Devang,
> 
> Thanks. As the testcase needs to compile down to assembly (to test the DWARF
> output), is the target triple really unnecessary?

All targets support DWARF but assembly syntax may not match, so yeah test is fine as it is.  Long term, it'd be good to start using llvm-dwarfdump once it matures for such tests.
-
Devang

> 
> Cheers,
> 
> James
> 
> -----Original Message-----
> From: Devang Patel [mailto:dpatel at apple.com] 
> Sent: 26 September 2011 18:19
> To: James Molloy
> Cc: Commit Messages and Patches for LLVM
> Subject: Re: [llvm-commits] [PATCH] Fix emission of debug data for global
> variables
> 
> James,
> 
> Your patch looks good. Please apply (remove target datalayout and target
> triple from the test case because it is unnecessary).
> Thanks!
> -
> Devang
> On Sep 26, 2011, at 9:03 AM, James Molloy wrote:
> 
>> Hi,
>> 
>> With the new debug information changes, global variables aren't emitted
> properly to DWARF. The DW_AT_decl_file field is incorrect.
>> 
>> This stems from DwarfCompileUnit.cpp:138:
>> 
>> unsigned FileID = DD->GetOrCreateSourceID(G.getContext().getFilename(),
>>                                           G.getContext().getDirectory());
>> 
>> G.getContext() returns a NULL metadatum for the new metadata format (it
> used to return the CompileUnit). This causes a new SourceID to be generated
> for the "null" file, and the global is assigned this incorrect SourceID.
>> 
>> Attached is a testcase and proposed patch. It inlines getFilename() and
> getDirectory() into DIGlobalVariable, returning the original
> getContext().getFilename() for old versions of the debug info and
> getFieldAs<DIFile>(6).getFilename() for new versions.
>> 
>> I've implemented it this way so that the old code path is identical to
> before. I'm not sure if this is the most perfect fix - as
> getFieldAs<DIFile>(6) is valid (seemingly) for all debug info versions,
> perhaps the best idea would be to remove the conditionalization and always
> return getFieldAs<DIFile>(6).getFilename/getDirectory() ?
>> 
>> 
>> Cheers,
>> 
>> James
>> 
>> 
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