[PATCH] [dwarfdump] Implement extraction of file information referenced in .debug_info.

[Frédéric Riss]

> On 04 Sep 2014, at 17:40, David Blaikie <dblaikie at gmail.com> wrote:
> 
> 
> 
> 
> On Thu, Sep 4, 2014 at 8:32 AM, Frédéric Riss <friss at apple.com <mailto:friss at apple.com>> wrote:
> 
>> On 04 Sep 2014, at 17:19, David Blaikie <dblaikie at gmail.com <mailto:dblaikie at gmail.com>> wrote:
>> 
>> 
>> 
>> 
>> On Thu, Sep 4, 2014 at 6:55 AM, Frederic Riss <friss at apple.com <mailto:friss at apple.com>> wrote:
>> Hi dblaikie, echristo, aprantl,
>> 
>> This is the merge of 2 patches:
>> 
>> Pass the DWARFUnit to DWARFDebugLine::getFileNameByIndex().
>> 
>> This way it can query the compilation dir when it is referenced (when a file references directory index 0, it refers to the compilation dir).
>> 
>> Alternatively (Though not necessarily better - open to opinions/preferences) DWARFUnit could have a wrapper for getFileNameByIndex and could be returned a zero/default/something that the DWARFUnit could detect and return the CU.
>> 
>> Or the DWARFDebugLine could be constructed with its unit, or just with the comp_dir of its unit so it didn't have to be passed in/queried for on every lookup?
>> 
> 
> I’m currently working on an alternative where I turn DWARFContext.cpp::getFileNameForUnit() and getFileLineInfoForCompileUnit() into LineTable methods. This way I reduce code duplication with what I’ve added to DWARFDebugInfoEntry::dump. I’ll see how that turns out.
> 
>> 
>> and:
>> 
>> [dwarfdump] Implement extraction of file information referenced in .debug_info.
>> 
>> This patch pretty prints the contents of the DW_AT_decl_file, DW_AT_call_file, DW_AT_decl_line and DW_AT_call line attributes.
>> Drop the const on the passed DWARFUnit to be able to call getLineTableForUnit (the line table construction is lazy, thus the getter might modify the Unit).
>> 
>> What pretty printing occurs for lines? (obviously for files this would allow you to print the file name rather than the file number - but DW_AT_decl/call_line already contain the line number, right?)
> 
> It’s just that they’re printed as decimal numbers. Which is indisputably more pretty for line numbers :-)
> 
> Agreed - though should we just print numbers as decimal generally? Which numbers benefit from being printed as hex I wonder?

All unsigned Forms get printed as hex by FormValue. As this covers addresses for example, I wouldn’t call that a bad choice. In fact, I can’t come up right now with another attribute I’d like to see printed as decimal (but I’m sure there are some).

> (might be worth splitting the line number part of the patch out - it might be easier (as you say, it's simply printing them as decimal rather than hex - doesn't depend on access to the line table you're adding here, etc) or it might be harder/different (if we end up changing the default & trying to decide if there are places where that new default would be problematic, etc))

I’ll do that once I finish the current rework.

Fred

> 
> Fred
> 
>> 
>> http://reviews.llvm.org/D5192 <http://reviews.llvm.org/D5192>
>> 
>> Files:
>>   lib/DebugInfo/DWARFContext.cpp
>>   lib/DebugInfo/DWARFDebugInfoEntry.cpp
>>   lib/DebugInfo/DWARFDebugInfoEntry.h
>>   lib/DebugInfo/DWARFDebugLine.cpp
>>   lib/DebugInfo/DWARFDebugLine.h
>>   test/DebugInfo/X86/2011-09-26-GlobalVarContext.ll
>>   test/DebugInfo/X86/fission-cu.ll
>>   test/DebugInfo/namespace.ll
>>   test/MC/MachO/gen-dwarf.s
>> 
> 
> 

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