Daedalus Dynarec Fixes

May 16th, 2007, 01:45 Posted By: Wally

Dynarec Fixes

In the previous update I mentioned that the dynarec wasn't working with Goldeneye:

...I can still only get the rom running with dynarec disabled on the PSP, so the framerate is currently just 6-7 fps. Interestingly it runs fine with dynarec on the PC with the same set of changes, so this indicates a bug somewhere in the PSP dynarec implementation.



I've spent a couple of evenings investigating this problem, and I've finally had a bit of luck in determining the root cause. As I suspected it was due to a bug in the PSP dynarec implementation - it turns out that I was fiddling addresses to compensate for the different endianness of the PSP twice (essentially having the same effect as not compensating in the first place).

The fix was very easy to implement (just a single line of code). It's quite a significant bug, so I'm hoping that it will fix dynarec issues with a few other roms too. Unfortunately it looks like the bug which is preventing dynarec working with Super Smash Bros. is a different issue, so I'll have to spend some more time investigating that.

I'm pleased to say that Goldeneye is now running fine with dynarec, so it now boots and runs the intro sequence very quickly. Although the intro and menu run at around 30-60fps, in-game is still very slow (around 5-8fps) so I need to profile this and see what's going on.

As I've hinted above, the next job is to have a look why dynarec is causing Super Smash Bros to hang. A cursory look revealed that it's still broken even when I disable most of the native code generation and directly call the interpretive instruction handlers from the compiled fragment. Because of this I think the problem has something to do with how traces are selected and the resulting fragments are linked together. I'll know more later in the week.

-StrmnNrmn

Source: http://strmnNrmn.blogspot.com

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