[llvm-dev] [CUDA] Lost debug information when compiling CUDA code

[Tom Stellard via llvm-dev]

On 06/14/2017 11:33 AM, Yuanfeng Peng wrote:
> Hi Tom,
> 
> Thanks for the response!  I wonder whether there's any other way that I can get the source level information when using cuda-gdb to debug a binary compiled by LLVM? Or is there any way to feed the IR files to NVCC and get a binary with the debug info I need?
> 

I don't know, I think you will have to ask NVIDIA about this.

-Tom

> Thanks!
> Yuanfeng
> 
> 
> ------------------ Original ------------------
> *From: * "Tom Stellard";<tstellar at redhat.com>;
> *Send time:* Wednesday, Jun 14, 2017 9:06 PM
> *To:* "Yuanfeng Peng"<yuanfengp at foxmail.com>; "via llvm-dev"<llvm-dev at lists.llvm.org>;
> *Subject: * Re: [llvm-dev] [CUDA] Lost debug information when compiling CUDA code
> 
> On 06/14/2017 02:59 AM, Yuanfeng Peng via llvm-dev wrote:
>> Hi,
>>
>> I needed to debug some CUDA code in my project; however, although I used -g when compiling the source code, no source-level information is available in cuda-gdb or cuda-memcheck. 
>>
> 
> The NVPTX backend in LLVM does not support DWARF emission.
> 
> -Tom
> 
>> Specifically, below is what I did:
>>
>> 1) For a CUDA file a.cu, generate IR files: clang++ -g -emit-llvm --cuda-gpu-arch=sm_35 -c a.cu;
>> 2) Instrument the device code a-cuda-nvptx64-nvidia-cuda-sm_35.bc (generated in the previous step), inserting a call to a hook function before each device memory access.  The hook function is defined in another file, b.cu.  Let's say we get a file named intrumented-a-device.bc after this step;
>> 3) Generate IR files for b.cu: clang++ -g -emit-llvm --cuda-gpu-arch=sm_35 -c b.cu;
>> 4) Link instrumented-a.device.bc with the device code generated for b.cu: llvm-link intrumented-a-device.bc b-cuda-nvptx64-nvidia-cuda-sm_35.bc -o ab-device.bc;
>> 5) Use llc, ptxas & fatbinary on ab-device.bc to get ab-device.ptx, ab-device.o & ab-device.fatbin;
>> 6) Call clang again the generate the host object file ab.o, with ab-device.o & ab-device.fatbin embedded;
>> 7) Link against libraries and get the final binary: a.out.
>>
>> The binary a.out fails with an exception I when run it; but when I try to debug it with cuda-gdb or cuda-memcheck, no source information was available.  Why?
>>
>> Thanks!
>> Yuanfeng Peng
>> 
>>
>>
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> 
> 
> 
>