Re: Issue with GDB 7.0 on MIPS(gcc 4.4.1)

Ian Lance Taylor
2011-11-14T18:01:59Z

> So I just request is there any patch available to fix this problem ?

I don't know. As I said earlier, current versions of gcc are much
better at debugging info for inlined functions, and are much better at
not incorrectly reporting variable values for optimized code. However,
I have no idea whether that will help with this specific problem.

Ian

> On Mon, Nov 14, 2011 at 12:20 PM, Ian Lance Taylor <iant@google.com> wrote:
>> naveen yadav <yad.naveen@gmail.com> writes:
>>
>>> My GCC  version 4.4.1. and  here is source code.
>>>
>>> http://gingacdn.lavid.ufpb.br/projects/ginga-j/repository/revisions/7e233c1906624b0e01698415987aada3fd8c3fe4/entry/gingaj/jvm/src/share/javavm/runtime/gc/generational/gen_markcompact.c
>>>
>>> and here is backtrace.
>>>
>>> mips-gdb> bt
>>> sweep (gen=0x5d5f508, ee=0x5c4300d0, numBytes=4294967295,
>>> gcOpts=0x5c3408f8) #1
>>> CVMgenMarkCompactCollect (gen=0x5d5f508, ee=0x5c4300d0,
>>> numBytes=4294967295, gcOpts=0x5c3408f8)
>>
>> Looking at the code, it's perfectly obvious that gdb is reporting the
>> arguments to sweep incorrectly.  The sweep function takes three
>> arugments: thisGen, base, and top.  It is called only from
>> CVMgenMarkCompactCollect, and that function takes four arguments, gen,
>> ee, numBytes, and gcOpts.
>>
>> Clearly the parameters to sweep are being reported incorrectly.  I don't
>> think you really needed me to tell you that.  I don't know where the bug
>> is, but my guess would be that gcc 4.4.1 is not generating correct debug
>> info for inlined functions.
>>
>> Ian
>>
>>
>>>
>>>  ......
>>>
>>> If you need more detail pls let me know..
>>> Thanks.
>>>
>>> On Fri, Nov 11, 2011 at 10:01 PM, Ian Lance Taylor <iant@google.com> wrote:
>>>> naveen yadav <yad.naveen@gmail.com> writes:
>>>>
>>>>> I am running one application and it generate core dump. When I run bt .
>>>>> (gdb) bt
>>>>> #0  sweep (gn=0x5d5f58, ef=0x5c43000, Bytes=429496729, gcOs=0x5c3408f)
>>>>> #1  CompactCollect (gn=0x5d5f58, ef=0x5c43000, Bytes=429496729, gcOs=0x5c3408f)
>>>>> ...
>>>>>
>>>>> In above case
>>>>> we got crash in wepp().
>>>>> CompactCollect () is main function and wepp() is another function
>>>>> which got called from CompactCollect ().
>>>>>
>>>>> When I check the assembly wepp() become inline.
>>>>> So i got bit surprise when i check that function parameter;s for both
>>>>> wepp() and CompactCollect () are same.
>>>>>
>>>>> So is it correct behaviour ? that calling and calle have same parameter
>>>>
>>>> Without any information about the source code, I don't see how we can
>>>> tell whether having the same parameters is correct behaviour or not.
>>>>
>>>> That said, it is certainly possible that the arguments of the inlined
>>>> function are not being displayed correctly.  Mainline gcc has gotten
>>>> quite a bit better about debug info for inlined functions and in general
>>>> for avoiding incorrect display of variables in optimized code.
>>>>
>>>> Ian
>>>>
>>