Subject: Re: [stella] 6502 superoptimizer update From: "Andrew Davie" <atari2600@xxxxxxxxxxxxx> Date: Tue, 31 May 2005 09:41:17 -0400 |
This is an extremely interesting idea, Fred. I had a quick play with it -- my computer is too slow to really let it have a good run at things. I don't know enough about it yet to make really meaningful suggestions, but I thought I'd just give you some encouragement to continue development. Cheers A ----- Original Message ----- From: "Fred Quimby" <c9r@xxxxxxxxxxx> To: <stella@xxxxxxxxxxxxxxxxxx> Sent: Tuesday, May 31, 2005 9:44 PM Subject: [stella] 6502 superoptimizer update >I found an amazing number of bugs in the first version of this I posted >last > week, and some of them were so bad that the program produced bogus results > or overlooked results that should have been good. I've attached the > updated > version (Alpha 0.02) to this post. > > Bugs fixed: > The program did not set N and Z flags based on initial accumulator value > Carry flag was inverted in compare operations > Branches often jumped to wrong target address > Various other errors in 6502 core > The "Estimated time" is severely underestimated (actually, it's still not > particularly accurate) > > New feature: > Still one unbounded immediate, but also up to two bounded immedates > allowed > ($00, $01, or $FF, which are probably the most common immediate values > loaded.) > > To do for next version: > Optimize code for speed! > Skip tests that rely on undefined flags > Skip tests that rely on undefined zero-page loads > Skip tests that store undefined register values > Stop if it is determined that the input code can be optimized > Post the source > Use something other than the gets() function to get stdin > Add command-line switches to specify: > - number of unbounded immediates allowed > - number of bounded immediates > - number of zero-page addresses > - Option to limit to a subset of the available instructions (legal > opcodes, > common opcodes, etc) > > Any other suggestions/comments/criticism? > > Archives (includes files) at http://www.biglist.com/lists/stella/archives/ > Unsub & more at http://stella.biglist.com > Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://stella.biglist.com
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