Building from scratch. Part 1

As I said in my previous post, we decided to integrate OCC into our team’s app test database at Intel. So I committed to enable that integration and proceeded to the task.

In order to get correct data when profiling an application (including using Intel Parallel Amplifier and Inspector), it must be compiled with /Zi option and linked with /DEBUG options to enable symbol information and store it in pdb. For performance tuning it should also be compiled with /O2 (maximize speed), and software vendors usually apply it. So, I needed all these three. This is not a default combination offered by Visual Studio (/Zi and /DEBUG come in Debug configuration with /Od and Release come with /O2 but without /Zi and /DEBUG). OCC ships *.vcproj files with those conventions. So I had to manually update all *.vcproj and for the Release config to set /Zi and /DEBUG. This was a first challenge, as OCC does not provide a single VS solution (*.sln) where I could select all projects and modify only once (fortunately Visual Studio provides multiple selection of the projects to change settings at once). So I had to reopen each solution one by one. I was luck as setting /Zi and /DEBUG could be done at the project file level and each source file (*.cxx) inherited these settings. This is not the case for optimization parameters (/O2) which are set in OCC shipped *.vcproj files on individual basis, for each source file. I believe this was done by intended oversight in some scripts generating *.vcproj from WOK. But this did not make my life easier two months ago when I initially had to set /Od for Release configurations (and I had to ‘grep’ project files and remove individual settings then). OCC folks in charge of the build environment and those who tweak OCC files might want to take this note into account.

Rebuilding OCC in MSVS (I am currently using 2005, by the way) was straightforward and seamless. Just had to reopen a new solution every few minutes and click Build Solution. The fact that there is no single global solution is a bit irritating though. I remember in the past we refrained from creating it because VS98 simply could not deal with it (running out of memory or something like that). Is it still the problem on newer VS (2003 and beyond), did anyone try ?
What was a bit annoying is number of warnings, sometimes really ugly (like intentional semicolon after some ‘if’ in Foundation Classes or constant arithmetic overflow in Modeling Algorithms). Right now in our team at Intel we are also fighting with warnings and set an aggressive goal to treat warnings as errors (we are not there yet however). Every code promotion will be rejected if it reveals warnings. Though it adds some overhead (and some developers complain) I believe this is beneficial for the product. So, if OCC team adopts that behavior sometime, we may see OCC compiled with 0 warnings ;-).

A few words on WOK. As I have to use my patched version of OCC 6.3.0 (to enable multi-threading and use some other modifications), I had to start with WOK. There are modifications in CDL extractor (that generates *.hxx from *.cdl) and in addition that are several new classes (with *.cdl definitions). Well, WOK is not something an average developer would (and should!) understand. It’s a beast in its own. Two months ago I spent a good deal of time to install it on my laptop and even this time when migrating to a lab workstation I had to be very careful in setting up an environment in multiple *.edl and *.bat files. Unless you spent several months or years with it, any mistake can cost you hours to figure out what goes wrong. I would seriously recommend you not to use it unless you really have to and understand what you are doing. WOK however was a great idea in 1990-es and let me shed some light on it.

(to be continued)

No comments:

Post a Comment