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Ahh. I knew it was generally 32 bit, but the info does say it has 64 bit integer units and some 128bit regs which is why I asked. Seems that wasn't really used much(the 64bit integer stuff at least)
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Couldn't we say the same about the GC/Wii? The CPU is basically 32 bit PPC based. How come moving to 64 bit helped that out so much?
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I mistyped that, I meant to say 30-40%. Would implementing fastmem on pcsx2 not benefit as much because of the way the PS2's hardware works or is it because not enough information is given about fastmem?
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Fastmem does not require 64bit (as has been said) and PCSX2 already has a a fast memory implementation (as has been said). None of us knows what Dolphin's "fastmem" is, and whether it's like what we have or something different.
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06-29-2015, 01:25 AM
(This post was last modified: 06-29-2015, 01:26 AM by JMC47.)
Doing fastmem on 32bit is definitely possible; just something that would have been fairly hacky (more than 64bit fastmem) and no one felt like implementing it.
It's not all fastmem though; one of the things that people miss is that Dolphin was maintaining a 32-bit and 64-bit JIT at the same time; part of what was bogging down the 64-bit JIT was maintaining the older 32-bit JIT. So yes, while the 64-bit JIT is faster naturally, and has fastmem implemented for it, the main reason why it was slower was maintaining the 32-bit JIT and keeping parity. I mean, if you're really dedicated, most of the advancements would have been possible on the 32-bit JIT.
For real though, 64-bit is better and has some big advantages for GameCube emulation; it's just nowhere near the numbers you'd see. Dolphin's JIT sped up by nearly 100% after the 32-bit JIT was dropped simply by having the freedom to implement things more easily and Fiora showing up.
Correction, over 100% in some games.
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I'm curious, how come having a 32-bit JIT in there was slowing it down? were the two not separate entities? was there some condition logic in there for most of it? Seems weird that removing a feature would make the same feature in a different bitness so much faster.
In your professional opinion, do you think we'd see any performance gains moving to 64-bit? I don't personally, but then I haven't coded in 64-bit, but neither have I seen any evidence to say otherwise.