<optimized out> in debugger

[Ehsan]

Hi,

When I trace the code in debugger, I get <optimized out> for some variables.
For example I set const double test_value = 1; but when I watch test_value it only shows <optimized out>.
I use last version of eclipse and debug with gdb debugger

How can I solve this problem?

Best regards.
Ehsan

[Timo Heister]

Ehsan,

is the code compiled in debug mode?
(https://stackoverflow.com/questions/5497855/what-does-value-optimized-out-mean-in-gdb)

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[Ehsan]

Dear Timo,

How can I compile in debug mode?

I tried make -debug but the problem is not solved.

Regards.
Ehsan

[Armin Ghajar Jazi]

Ehsan,

you have to specify the type of build when calling the cmake(precompiler) which according to documentation is:

$ cmake -DCMAKE_BUILD_TYPE="Debug" .

$ cmake -DCMAKE_BUILD_TYPE="Release" .

Also take a look at the following:

http://www.dealii.org/developer/users/cmakelists.html

it gives you a nice overview of cmake-build and compiling.

cheers,

armin

--

[Ehsan]

Dear Armin,

I did as you recommended, but the problem is not solved yet !!

Best regards.
Ehsan

[Ehsan]

Hi,
I compiled the code in debug mode, but still get <optimized out> in debugger for some variables.
Is this a usual problem or I am doing something wrong?
Regards.
Ehsan

[Wolfgang Bangerth]

> I compiled the code in debug mode, but still get <optimized out>in debugger
> for some variables.
> Is this a usual problem or I am doing something wrong?

It's not common but it may happen on rare occasions. I'm still surprised
though. What do you get when you say
ldd my_executable | grep deal_II
where my_executable is the executable program in the directory you're working
in? It should show libdeal_II.g.so if you are linking against the debug mode
libraries (not the .g. in the middle).

The typical case where a variable may be optimized out even in debug mode is
code like this:

class X {
static const unsigned int dim = 2;
};

Here, 'dim' is essentially just an alias for the number 2. It may not have a
memory location. Otherwise, compilers have become pretty good at producing
reasonable debug information.

Best
W.

--
------------------------------------------------------------------------
Wolfgang Bangerth email: bang...@math.tamu.edu
www: http://www.math.tamu.edu/~bangerth/

[Ehsan]

Hi,
I get libdeal_II.g.so.8.1.0

It is really strange !!
I checked whole code. when I write for example:

const double AAA = 1.2;
right_hand_side.vector_value_list(fe_values.get_quadrature_points(), rhs_values);
const double BBB = 1.2;

the debugger shows the value of AAA but it returns <optimized out> for  BBB.

What happens inside right_hand_side.vector_value_list that causes this problem?

Best regards.
Ehsan

[Wolfgang Bangerth]

> I get libdeal_II.g.so.8.1.0
>
> It is really strange !!
> I checked whole code. when I write for example:
>
> const double AAA = 1.2;
> right_hand_side.vector_value_list(fe_values.get_quadrature_points(), rhs_values);
> const double BBB = 1.2;
>
> the debugger shows the value of AAA but it returns <optimized out> for BBB.

Do you ever reference BBB? And at what point do you stop the debugger when you
try to print BBB?

> What happens inside right_hand_side.vector_value_list that causes this problem?

I don't know. This is the wrong forum for your question. We can help you with
questions about deal.II, but you are asking a question of why your compiler
does not communicate information to the debugger (we don't even know which
compiler or debugger). This is a question for the compiler/debugger people.

[Ehsan]

Dear bangerth,

I use last version of eclipse and gdb.
yes, you are right, may be this problem is not related to deal ii.
I will try to install eclipse and gdb again maybe this solve the problem.

So many thanks for everyone's reply.

Best regards.
Ehsan

[Mark McClure]

If you are inside an openmp loop, even if the number of threads is 1, then variables declared locally inside the loop may appear as 'optimized out' it in the debugger. Temporary solution during debugging is to remove the openmp pragma in front of the for loop.