Closed Bug 689779 Opened 11 years ago Closed 11 years ago
Monkey: Eliminate negative zero checks for a*a
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.
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_?
Assignee: general → tcole
Status: NEW → ASSIGNED
Attachment #563502 - Flags: feedback?(dvander)
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.
Attachment #563524 - Flags: feedback?(dvander)
Comment on attachment 563524 [details] [diff] [review] v2 Nice.
Attachment #563524 - Flags: feedback?(dvander) → review+
11 years ago
I still don't have commit access, but that's no reason to let this bitrot.
11 years ago
Status: ASSIGNED → RESOLVED
Closed: 11 years ago
Resolution: --- → FIXED
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