idb & idbc (Intel Debugger)

Overview

Typically a debugger is used to execute a program and pause under certain conditions (e.g. at specific line numbers) to examine the state of the program, e.g. to look at values associated with the program’s variables. Using the debugger it is also possible to step through execution of the program line by line.

The Intel debugger is supplied with the Intel ifort and icc compilers, and can be used with either Intel and GNU compilers. GUI and command line interfaces are available, see the idb documentation for more details.

• idb – GUI version of the debugger
• idbc – Command line version of the debugger

Restrictions on use

See restrictions on the Intel Compilers page.

Debugging sessions should use the interactive queue, do not run the debugger on the login node.

Set up procedure

The GUI and command-line debuggers (idb and idbc) are available as part of the compiler suites so simply load the required compiler module to set up the debugger for that compiler:

To debug C/C++ code choose one of:

module load compilers/intel/c/12.0.5

module load compilers/intel/c/11.1.075

To debug fortran code choose one of:

module load compilers/intel/fortran/12.0.5

module load compilers/intel/fortran/11.1.064

Before using the Intel debugger a program must be compiled with the appropriate flag, e.g. -g for the Intel and GNU compilers. Note: the -g flag may change the default level of optimisation, check the compiler documentation for further information, but a simple example would be:

icc -g -o my_program myprogram.c

The GUI version requires X Windows, e.g. use the -X flag with ssh when logging in, plus an X server if using the Microsoft Windows operating system locally. See the instructions for Windows users for more details.

Running the application

Debugging is an interactive process and should use the interactive queue, using the SGE command qrsh. For example, to run the debugger in the (where my_program is located) use:

GUI version:

qrsh -cwd -V -l inter -l twoday idb ./my_program

command-line version

qrsh -cwd -V -l inter -l twoday idbc ./my_program

and wait to connect to a remote node on which the debugger will start. You should see something like the following for the command-line debugger:

qrsh -cwd -V -l inter -l twoday idbc ./my_program
Intel(R) Debugger for applications running on Intel(R) 64, Version 12.0, Build [76.252.2]
------------------ 
object file name: ./my_program 
Reading symbols from /users01/mxyzabc2/dev/src/my_program...done.
(idb)

(idb) is the debugger prompt at which you can enter commands. For example:

• To run your code enter r optional-args where optional-args are any command-line args you would normally give to my_program when you run it.
• To quit the debugger enter q which will return control to the log in node.

Further info

Documentation can be found on the CSF:

• Version 12.0.5: $INTELROOT/Documentation/en_US/debugger/
• Version 11.1.075: $INTELROOT/Documentation/en_US/idb/
• Version 11.1.064: $INTELROOT/Documentation/en_US/idb/

On the CSF the firefox application can be used to view the html files, and evince can be used to view the pdf files.

Updates

None.