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Old 05 December 2020, 19:43   #1
falken
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How to config Advanced Jit Settings?

I would like to know how you configure this section of the emulator, taking into account that a 68060 processor is in use. I would also like to know where you can read what each parameter of that section does.

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Old 06 December 2020, 16:17   #2
Toni Wilen
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Hard flush = Affects how JIT handles CPU cache flushed. No hard flush: keep translated code in memory but mark it as "needs to be checked", reuses existing translated code if original m68k code didn't change. If hard flush: always flush all translated code. Performance optimization. Without it static code (like OS/ROM code) gets translated again and again after each cache flush.

No flags = if JIT detects that following instruction(s) are known not to care about CPU flag contents, skip CCR setup part of instruction emulation. Performance optimization. Can be always enabled, if something breaks when it is enabled: JIT bug.

Constant jump = not sure.

Direct = memory accesses go directly to memory. Bypass memory mapping. Much faster. Can only work if "normal" RAM, no mirrors, no on the fly remap etc.. For example can't be used (disabled automatically) if emulating accelerator board with map rom.

Indirect = memory accesses use normal UAE memory banking method. Works always.

Catch unexpected exceptions = if JIT crashes (because program did something too stupid or corrupted stack etc..) tries to recover.
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Old 07 December 2020, 18:43   #3
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Quote:
Originally Posted by Toni Wilen View Post
Hard flush = Affects how JIT handles CPU cache flushed. No hard flush: keep translated code in memory but mark it as "needs to be checked", reuses existing translated code if original m68k code didn't change. If hard flush: always flush all translated code. Performance optimization. Without it static code (like OS/ROM code) gets translated again and again after each cache flush.

No flags = if JIT detects that following instruction(s) are known not to care about CPU flag contents, skip CCR setup part of instruction emulation. Performance optimization. Can be always enabled, if something breaks when it is enabled: JIT bug.

Constant jump = not sure.

Direct = memory accesses go directly to memory. Bypass memory mapping. Much faster. Can only work if "normal" RAM, no mirrors, no on the fly remap etc.. For example can't be used (disabled automatically) if emulating accelerator board with map rom.

Indirect = memory accesses use normal UAE memory banking method. Works always.

Catch unexpected exceptions = if JIT crashes (because program did something too stupid or corrupted stack etc..) tries to recover.
Thank you for the valuable info!
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Old 07 December 2020, 23:39   #4
rutra80
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From some old docs:

Constant Jump = If this enabled, unconditional branches will not end a block. Effectively, UAE-JIT compiles "through" them. Generally, that's a good idea, as it improves performance.
However, it makes soft cache flushing impossible for some blocks, so if you experience lots and lots of soft cache flushes (e.g. when using a Mac emulator), you might try "no" and see whether it does any better.
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Old 08 December 2020, 00:03   #5
Aladin
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in CopyMemAIO documentation:

http://aminet.net/package/util/boot/CopyMemAIO

For a fast emulation most important are the Advanced JIT Settings in WinUAE:
Cache Size: 16MB
Check FPU Support
Check Constant Jump
NoCheck Hard flush
Select Direct
Check No flags
Check Catch unexpected exceptions
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Old 08 December 2020, 16:29   #6
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Thank you guys ! With that information, you can get a better insight into those functions.
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