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mkst / maspsx

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Fix missing NOP before NOR instruction #40

Closed bismurphy closed 11 months ago

bismurphy commented 11 months ago

As part of SOTN Decomp, I was working on this function. It matches, aside from the missing NOP at assembly address 1F8.

https://decomp.me/scratch/aYRXv

It appears that when loading $v0, then applying a nor to it (in this case, nor with 0 to invert all the bits), a nop is needed in between. Changing the compiler to PSYQ3.5 properly adds the nop to the compiled assembly and results in a perfect match.

Testing locally (with this function's code copied over), adding nor to the store_mnemonics list fixed this issue.

I am not sure if there is a different list that nor should go into (since it's not a store mnemonic), or if store_mnemonics should be renamed now that we have found a non-storage instance where that nop is needed. So this PR may need to be adjusted, but at least this is a starting point toward a solution for this issue.

mkst commented 11 months ago

I think the "nor" should be added to the single_reg_loads array instead - I've tested this locally and it's inserting the nop correctly.

bismurphy commented 11 months ago

Done, thank you for the feedback!

mkst commented 11 months ago

Thanks for finding and fixing a(nother) bug in maspx!