Created attachment 562892 [details]
In the attached benchmark, we could get a significant speedup from removing the negative zero check on the multiplication. We should be able to do this in MIR by seeing that (a * a) will never be negative.
Created attachment 563502 [details] [diff] [review]
Speedup is 1.12x, but I need some feedback on the patch's specifics:
1) I think isCongruent is a more specific (and costly) test that we want for this, but I could be quite wrong.
2) Is there a way to implement this check without having to copy the body of MBinaryArithInstruction::foldsTo?
3) Should I add a setter for canBeNegativeZero_?
Created attachment 563524 [details] [diff] [review]
Shorter patch using congruentTo and calling out to super (requires us to re-acquire lhs/rhs). It seems to be epsilon slower than v1 in the benchmark, but it's well within the error bars.
Comment on attachment 563524 [details] [diff] [review]
Created attachment 567918 [details] [diff] [review]
I still don't have commit access, but that's no reason to let this bitrot.