[LLVMdev] Problem with x86 32-bit debug information ?

[Seb]

Hi James,

clang is able to generate correct debug informations for 64-bit target at
-O2. My feeling, given some other experiments I've done,  is that debug
information generated for x86 32-bit might be broken for parameters as long
as they are not 'homed' in the code (local copy to an automatic variable).
It seems that when llvm.declare is turned into a llvm.value for parameter
there is something incorrect with respect to parameters debug informations
that is generated by clang/llvm. I just would like confirmation of this.

Thanks for your answer
Best Regards
Seb

2012/3/7 James Molloy <james.molloy at arm.com>

>  Hi Seb,****
>
> ** **
>
> Clang cannot generate debug information for something that it has
> optimised away. You should reduce the optimisation level.****
>
> ** **
>
> In general debug information is only really accurate at –O0.****
>
> ** **
>
> Cheers,****
>
> ** **
>
> James****
>
> ** **
>
> *From:* llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] *On
> Behalf Of *Seb
> *Sent:* 07 March 2012 13:17
> *To:* llvmdev at cs.uiuc.edu
> *Subject:* [LLVMdev] Problem with x86 32-bit debug information ?****
>
> ** **
>
> Hi all,
>
> I'm using trunk version of LLVM/CLANG.
> When I compile attached files on my 64-bit Ubuntu 10.04 LTS system as
> follows:
>
> clang -O2 -g check.c main.c -o check64
>
> When I do gdb check64 and set a breakpoint to the check routine and
> executes to the breakpoint, I've got:
>
> Breakpoint 1, check (result=0x601110, expect=0x601020, n=53) at check.c:7
> 7    {
>
> As you can see I can inspect 'n' value.
>
> Now if I compile for x86 32-bit as follows:
>
> clang -m32 -O2 -g check.c main.c -o check32
>
> When I do gdb check32 and set a breakpoint to the check routine and
> executes to the breakpoint, I've got:
>
> Breakpoint 1, check (result=<value optimized out>,
>     expect=<value optimized out>, n=0) at check.c:7
> 7    {
>
> As you can see I can NOT inspect 'n' value. Is there a way to inforce even
> at -O2 clang to generate debug informations so that I can inspect 'n' value
> ?
> Or is it a BUG from clang for x86 32-bit ?
> Thanks for your answers.
> Best Regards
> Seb****
>
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