[Scummvm-devel] templates, visuals, getDevices()
matt at use.net
Tue Mar 3 21:12:47 CET 2009
On Tue, 3 Mar 2009, Joost Peters wrote:
> Max Horn schreef:
>>>> Maybe if you tell us what errors you get, with which compiler, we can
>>> I was aware of the proper class names, but those forward declatations
>>> were the only way I've found so far that made the compiler in
>>> question (SGI MIPSpro) happy.
>> My first thought is: Gee, yet another buggy compiler :-). One approach
>> to solve this problem is to switch to GCC, e.g. maybe this one works: <http://freeware.sgi.com/cd-2/relnotes/gcc.html
>> > or the 4.2.3 gcc provided by pkgsrc: <http://mail-index.netbsd.org/pkgsrc-users/2008/02/19/msg000417.html
> While compiling with GCC certainly is an option (it's what I use since I
> don't have MIPSpro), the code that is produced tends to be less well
> optimized than that generated by MIPSpro, and on low-end hardware, this
> is the difference between ScummVM running acceptably or not.
> To that end, it would be nice if we could find a non-invasive workaround
> to get MIPSpro working again.
> OTOH, I've only used GCC3, so perhaps 4 produces considerably faster code..
GCC 4.x may or may not produce better code for the MIPS CPU you are
targeting. There are some things that some people I know have done to get
good performance from GCC-compiled programs on the PS2:
1. Favor -Os over -O2. The cache on the MIPS CPU in the PS2 is retardedly
small, and the cache misses can be a major drag.
2. Generate runtime profiles using -fprofile-arcs on a non-embedded
platform, and then feed the profiling data back into GCC when you are
cross-compiling for your embedded target. This helps reorder branches,
functions, and segregate out lesser used code. This increase in locality
can be a big boost on cache-limited platforms like the PS2. Note that if
you do more than reordering, you should really exercise all the game
engines decently. Like, say, making every supported game go in-game.
Anything not captured in the runtime profile will not necessarily perform
worse, but it definitely won't perform any better.
3. In lieu of the Link Time Optimizations that will be part of the next
GCC, there is a way to get a similar effect. For each directory, make a
.cpp that #includes all the other .cpp files in the directory. Then
include all of those "meta" cpp files into one big .cpp file. Get that
file compiling (there can sometimes be name collisions if people are using
'static' and other globals). If there are entry points, they need to be
marked as such. This allows GCC to optimize across the entire
program at once, instead of a unit at a time. Besides yielding a smaller
binary (in my experience), the constant folding and tree optimizations in
GCC 4.3 and above can do a really great job.
The simplest thing would be to use GCC 4.3.x and -Os to see if that gets
you the performance you're looking for. If not, try these other, deeper
I hope this helps!
tangled strands of DNA explain the way that I behave.
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