PPU LLVM: Improve VMADDFP and VNMSUBFP #7798
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Pushed a version where native FMA is active for VNMSUBFP as well, neko said it doesn't matter. |
- Use native FMA to emulate VMADDFP, with a fallback for processors that don't support FMA - Use native FMA to emulate VNMSUBFP as well, but note that it differs from the emulated path with regards to negative zero
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This PR improves the accuracy of the
VMADDFPandVUMSUBFPPPU instructions.VMADDFPwas written to use native FMA if possible, but I couldn't get the accuracy ofVNMSUBFPto match the behavior of the emulated FMA path, so it's not using native FMA for now.This fixes an issue in Nier that caused a boss's turn rate to go haywire, which would then cause the boss to dive out of bounds rendering the fight impossible.
fixes #7158
I tested against the tests here: https://github.com/RPCS3/ps3autotests/tree/master/tests/cpu/ppu_vpu
ppu_vpu diff against master
diff_vpu_fma_master.txt
ppu_vpu diff against this pr
Diff_vpu_fma_pr.txt
ppu_vpu diff against this pr with native fma for
VNMSUBFP(there is a regression with positive and negative zero)diff_vnmsub_native_fma.txt
If you want to test make sure you remove the PPU cache before testing, since this PR doesn't invalidate it.