llvm dev - Aug 2009 - [LLVMdev] Debug information and bitcode linking patch

Hi,

The enclosed patch preserves debug information about compilation units, 
functions, and line number information when doing bitcode linking. I'm 
not easily able to try this for non-bitcode linking. Could someone 
familiar with debug info take a look and tell me if it appears to be benign?

The rational is that formerly the compile units and subprogram 
definitions were made into a single occurrence after linking, which 
really messed up the debug info. This patch keeps them separate, as they 
should be.

This is a fix for http://llvm.org/bugs/show_bug.cgi?id=4530

-Rich

Richard Pennington wrote:
> Hi,
> 
> The enclosed patch preserves debug information about compilation units, 
> functions, and line number information when doing bitcode linking. I'm 
> not easily able to try this for non-bitcode linking. Could someone 
> familiar with debug info take a look and tell me if it appears to be 
> benign?
> 
> The rational is that formerly the compile units and subprogram 
> definitions were made into a single occurrence after linking, which 
> really messed up the debug info. This patch keeps them separate, as they 
> should be.
> 
> This is a fix for http://llvm.org/bugs/show_bug.cgi?id=4530
> 
> -Rich
> 
Oops. the patch.


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On Sun, Aug 16, 2009 at 11:47 AM, Richard Pennington<rich at pennware.com>
wrote:
> Richard Pennington wrote:
>>
>> Hi,
>>
>> The enclosed patch preserves debug information about compilation units,
>> functions, and line number information when doing bitcode linking.
I'm not
>> easily able to try this for non-bitcode linking. Could someone familiar
with
>> debug info take a look and tell me if it appears to be benign?
>>
>> The rational is that formerly the compile units and subprogram
definitions
>> were made into a single occurrence after linking, which really messed
up the
>> debug info. This patch keeps them separate, as they should be.
>>
>> This is a fix for http://llvm.org/bugs/show_bug.cgi?id=4530
>>
>> -Rich
>>
>
> Oops. the patch.
>
This is not the right approach. This patch allows optimizer to remove
debug info for functions that are still present in the module.

Plus, very soon (as soon as 2.6 release branch is created) the LLVM IR
will stop using GlobalVariables to encode debug info. Stay tuned.
-
Devang