llvm dev - Dec 2017 - Help in generating Debug symbols

Hi Florian,

   Thanks for the reply.

On Fri, Dec 8, 2017 at 6:48 PM, Florian Hahn <florian.hahn at arm.com>
wrote:
> Hi,
>
> On 08/12/2017 06:24, Nagaraju Mekala via llvm-dev wrote:
>>
>> Hi all,
>>
>>    I am new to LLVM. Currently working on adding an embedded target to
>> LLVM backend.
>>    I was able to generate the object file for our target using LLVM and
>> Clang framework.
>>    The generated object file doesn't contain any debug symbols in
it.
>>
>
> What commands are you using?
llvm/bin/clang -g -target xmb -c a.c
> Do you get object files with debug info for> other backends?
Yes, for ARM and X86 targets debug symbols are generating fine.
> If you pass `clang -g`, debug info should be generated. In> the IR, you
should have !dbg metadata.
Yes I can see the !dbg metadata in ll file:

a.c
---------------------------
int main()
{
  printf ("Hello World\n");
 return 0;
}

a.ll
--------------------------------
@.str = private unnamed_addr constant [13 x i8] c"Hello World\0A\00",
align 1

; Function Attrs: nounwind
define i32 @main() #0 !dbg !4 {
entry:
  %retval = alloca i32, align 4
  store i32 0, i32* %retval, align 4
  %call = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([13
x i8], [13 x i8]* @.str, i32 0, i32 0)), !dbg !12
  ret i32 0, !dbg !13
}

Thanks,
Nagaraju
.
> Cheers,
> Florian

> -----Original Message-----
> From: llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] On Behalf Of
> Nagaraju Mekala via llvm-dev
> Sent: Friday, December 08, 2017 10:06 AM
> To: Florian Hahn
> Cc: llvm-dev at lists.llvm.org; nd
> Subject: Re: [llvm-dev] Help in generating Debug symbols
> 
> Hi Florian,
> 
>    Thanks for the reply.
> 
> On Fri, Dec 8, 2017 at 6:48 PM, Florian Hahn <florian.hahn at
arm.com> wrote:
> > Hi,
> >
> > On 08/12/2017 06:24, Nagaraju Mekala via llvm-dev wrote:
> >>
> >> Hi all,
> >>
> >>    I am new to LLVM. Currently working on adding an embedded
target to
> >> LLVM backend.
> >>    I was able to generate the object file for our target using
LLVM and
> >> Clang framework.
> >>    The generated object file doesn't contain any debug symbols
in it.
> >>
> >
> > What commands are you using?
> llvm/bin/clang -g -target xmb -c a.c
> 
> > Do you get object files with debug info for> other backends?
> Yes, for ARM and X86 targets debug symbols are generating fine.
> 
> > If you pass `clang -g`, debug info should be generated. In> the IR,
you
> should have !dbg metadata.
> Yes I can see the !dbg metadata in ll file:
That is not surprising, if all you have done is add a new target.

If you use `clang -g -S` to get an asm file, do you see the
.debug_info and other .debug_* sections?  Do you see .loc directives?
If not, the problem is somewhere in how your target interacts with
CodeGen.  If you see these things in the assembler source, but
assembling to an object file loses the information, then there is
likely some problem with how your target interacts with the MC
layer.  Or, if you are not emitting ELF or MachO object files, but
have your own object format, then you might have a problem with how 
you have implemented the object file stuff.

I hope this helps narrow down the problem for you.
--paulr
> 
> a.c
> ---------------------------
> int main()
> {
>   printf ("Hello World\n");
>  return 0;
> }
> 
> a.ll
> --------------------------------
> @.str = private unnamed_addr constant [13 x i8] c"Hello
World\0A\00",
> align 1
> 
> ; Function Attrs: nounwind
> define i32 @main() #0 !dbg !4 {
> entry:
>   %retval = alloca i32, align 4
>   store i32 0, i32* %retval, align 4
>   %call = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([13
> x i8], [13 x i8]* @.str, i32 0, i32 0)), !dbg !12
>   ret i32 0, !dbg !13
> }
> 
> Thanks,
> Nagaraju
> .
> > Cheers,
> > Florian
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

Hi Paulr,

   Thanks for the pointers.
   In my case debug symbols are not getting generated even in asm
file. I will check the target interaction with Codegen.

Thanks,
Nagaraju

On Sat, Dec 9, 2017 at 3:35 AM, Robinson, Paul <paul.robinson at sony.com>
wrote:
>> -----Original Message-----
>> From: llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] On Behalf Of
>> Nagaraju Mekala via llvm-dev
>> Sent: Friday, December 08, 2017 10:06 AM
>> To: Florian Hahn
>> Cc: llvm-dev at lists.llvm.org; nd
>> Subject: Re: [llvm-dev] Help in generating Debug symbols
>>
>> Hi Florian,
>>
>>    Thanks for the reply.
>>
>> On Fri, Dec 8, 2017 at 6:48 PM, Florian Hahn <florian.hahn at
arm.com> wrote:
>> > Hi,
>> >
>> > On 08/12/2017 06:24, Nagaraju Mekala via llvm-dev wrote:
>> >>
>> >> Hi all,
>> >>
>> >>    I am new to LLVM. Currently working on adding an embedded
target to
>> >> LLVM backend.
>> >>    I was able to generate the object file for our target using
LLVM and
>> >> Clang framework.
>> >>    The generated object file doesn't contain any debug
symbols in it.
>> >>
>> >
>> > What commands are you using?
>> llvm/bin/clang -g -target xmb -c a.c
>>
>> > Do you get object files with debug info for> other backends?
>> Yes, for ARM and X86 targets debug symbols are generating fine.
>>
>> > If you pass `clang -g`, debug info should be generated. In> the
IR, you
>> should have !dbg metadata.
>> Yes I can see the !dbg metadata in ll file:
>
> That is not surprising, if all you have done is add a new target.
>
> If you use `clang -g -S` to get an asm file, do you see the
> .debug_info and other .debug_* sections?  Do you see .loc directives?
> If not, the problem is somewhere in how your target interacts with
> CodeGen.  If you see these things in the assembler source, but
> assembling to an object file loses the information, then there is
> likely some problem with how your target interacts with the MC
> layer.  Or, if you are not emitting ELF or MachO object files, but
> have your own object format, then you might have a problem with how
> you have implemented the object file stuff.
>
> I hope this helps narrow down the problem for you.
> --paulr
>
>>
>> a.c
>> ---------------------------
>> int main()
>> {
>>   printf ("Hello World\n");
>>  return 0;
>> }
>>
>> a.ll
>> --------------------------------
>> @.str = private unnamed_addr constant [13 x i8] c"Hello
World\0A\00",
>> align 1
>>
>> ; Function Attrs: nounwind
>> define i32 @main() #0 !dbg !4 {
>> entry:
>>   %retval = alloca i32, align 4
>>   store i32 0, i32* %retval, align 4
>>   %call = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([13
>> x i8], [13 x i8]* @.str, i32 0, i32 0)), !dbg !12
>>   ret i32 0, !dbg !13
>> }
>>
>> Thanks,
>> Nagaraju
>> .
>> > Cheers,
>> > Florian
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev