Debug with the -O3 optimization option

Lee Holeva

I'm using CCS4.2.3 with a XDS510USB emulator and when debugging DSP code having been built with the -O3 optimization option I notice that when in debug mode some local variables are not displayed and some variables which are displayed show incorrect values. This is particularly true for register variables. Would changing to a faster emulator, such as a XDS560v2, change this, or is this behavior simply a consequence of using -O3?

Lee

over 13 years ago

0 Ki over 13 years ago

TI__Guru**** 463441 points

Hi Lee,

-o3 is a pretty aggressive level of optimization. That would certainly impact your debug visibility. Are you also building with -g?

The below wiki topic has some good information on your debug visibility with optimization:

http://processors.wiki.ti.com/index.php/Debug_versus_Optimization_Tradeoff

Thanks

0 Lee Holeva over 13 years ago in reply to Ki

Genius 4615 points

Ki-Soo Lee said:

-o3 is a pretty aggressive level of optimization. That would certainly impact your debug visibility. Are you also building with -g?

In the package.bld file I have -g -O3. My app runs noticably faster after built this way versus the default -O2.

Lee

0 Ki over 13 years ago in reply to Lee Holeva

TI__Guru**** 463441 points

Lee,

I checked with a colleague who is more knowledgeable on these matters and he confirmed that regardless of the -g option, -o3 is a very aggressive optimization setting and you lose a lot of debug visibility. Variables get optimized out (stored in registers or on the stack), things get aggressively reordered, etc. The issues you are seeing are expected.

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Debug with the -O3 optimization option