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

[Frédéric Riss]

> On Sep 30, 2014, at 5:43 PM, David Blaikie <dblaikie at gmail.com> wrote:
> 
> 
> 
> On Thu, Sep 4, 2014 at 8:53 AM, Frédéric Riss <friss at apple.com <mailto:friss at apple.com>> wrote:
> 
>> On 04 Sep 2014, at 17:40, David Blaikie <dblaikie at gmail.com <mailto: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).
> 
> You can probably add DW_AT_lower_bound, DW_AT_upper_bound, and DW_AT_count to the list of attributes that might make more sense as (signed) decimal. (just something I came across in a test case)

Are you sure about the (signed) part? I have been working on a patch to add this, but now I’m wondering… What makes it a signed entity, I’m not seeing anything in the standard that mandates it. It’s not a big deal because anything we generate should be OK, but I thought I’d ask before submitting the pacth (which is actually not that obvious as we don’t have getAsSignedConstant() right now, and getting that tested isn’t that easy).

Fred

> 
>> (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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