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

[James Molloy]

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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