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zcash / pasta_curves

Rust implementation for zcash/pasta
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Worth consider asmffi asm implementation for pasta fields? #62

Open CPerezz opened 1 year ago

CPerezz commented 1 year ago

I came across https://github.com/iden3/ffiasm and wondered if this asm code has ever been benched against the actual implementation. And if so, whether it is faster.

I did some initial exploration and saw that most of the asm backend we have at PSE (see here) is as optimized as what rust here compiles too. (At least for fns like double as seen in: https://github.com/zcash/pasta_curves/pull/44#issuecomment-1407313926

From a quick look, to functions like double or square looks like the exact same thing or even slightly worse:

Square

Instruction asmffi PSE-ASM (Ash)
PUSH 4 0
MOV 20 19
XOR 1 2
MULX 36 36
ADCX 39 28
ADOX 28 0
BT 2 0
SHL 1 0
ADD 2 28
SUB 2 2
SBB 0 6
CMOVC 0 8
TOTAL 135 129

Double

From a superficial view is already obvious that PSE-ASM is has less ops.

So I just wonder if anyone has done a deep analysis on that. As from a short check, looks like is not worth even considering it.