[LLVMdev] debugging LLVM generated executables???

[Chris Lattner]

On Wed, 7 May 2008, Mark Oskin wrote:
> Just re-sending this.  Anyone have any suggestions on how to proceed
> with debugging LLVM produced executables?  The problem appears to be
> register-allocated variables.  Global variables and syntax lines do
> get symbols using the llc / as method I described below.  -Mark

Have you considered adding your pass to llvm-backend.cpp in llvmgcc?  This 
would allow you to use llvm-gcc from the command line, without having to 
invoke individual tools directly.

-Chris

> On May 6, 2008, at 7:36 AM, Mark Oskin wrote:
>
>>
>>> I think you probably need to pass -O0 to llvm-ld.  The link-time
>>> optimizations are probably killing your debug info.
>>>
>> No dice.  Doing it this way makes gdb spew out this:
>>
>> warning: Could not find object file "/var/folders/cQ/cQ+L3+RP2RWOpE
>> +8ZNQdPU+++TI/-Tmp-//ccVljWhn.o" - no debug information available for
>> "defs.h"
>>
>> And then no debug symbols are available.
>>
>> I also discovered a major down side to the "solution" I found last
>> night.  While the line number data does get successfully transfered
>> into gdb, I cannot inspect any variables.  Those appear to have been
>> lost.
>>
>> Any other suggestions out there?
>>
>> thanks!
>>
>> -mark
>>
>>> --Owen
>>>
>>> On May 5, 2008, at 8:21 PM, Mark Oskin wrote:
>>>
>>>> Hi everyone again,
>>>>
>>>> I did discover the following works (see below).  However, does
>>>> anyone
>>>> know of the "proper" way with LLVM?
>>>>
>>>> llvm-gcc -g -c -emit-llvm helloworld.c
>>>> opt -load=mypass.dylib -mypass < helloworld.o > helloworld-mypass.o
>>>> llc -fast -f -o helloworld.s helloworld-mypass.o
>>>> as -o helloworld-prime.o
>>>> gcc -o helloworld helloworld-prime.o
>>>> gdb helloworld
>>>>
>>>> On May 5, 2008, at 4:17 PM, Mark Oskin wrote:
>>>>
>>>>> Hi everyone,
>>>>>
>>>>> I have a question that seems simple, but has been confounding me
>>>>> for
>>>>> several hours.  I'd like to debug a binary produced with LLVM.  For
>>>>> the life of me, I can't get any symbols into gdb and llvm-db won't
>>>>> even start the program nor load any useful information about it.
>>>>> Here's my current strategy (which isn't working):
>>>>>
>>>>> llvm-gcc -g -O0 -c -emit-llvm helloworld.c
>>>>> opt -load=mypass.dylib -mypass < helloworld.o > helloworld-mypass.o
>>>>> llvm-ld -native -o helloworld helloworld-mypass.o
>>>>> gdb helloworld
>>>>>
>>>>> I've tried several variations on the above.
>>>>>
>>>>> Any suggestions?
>>>>>
>>>>> Note, what is critical about the whole thing is I must run
>>>>> "mypass" on
>>>>> the bytecode file.  I'm hoping there's an easy fix, that will both
>>>>> allow me to run my arbitrary pass, and debug a program.
>>>>>
>>>>> thanks,
>>>>>
>>>>> -Mark
>>>>> _______________________________________________
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>>>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>>>
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-Chris

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