Lawrence Mitchell

Note that if you do that, the usage I implemented there has this performance antipattern which you may wish to try and address https://github.com/firedrakeproject/firedrake/issues/3560

Just to add some more API requests into the mix. From the libcudf side of things, we would want to do this on non fixed-width data types (e.g. string columns)...

> How does it perform if you turn off `comm_subexpr_elim`? Same, indeed with all optimisations off it's still quadratic, just faster overall: ``` for i in 1 200 400 800...

I don't _think_ so. The expression is (for $N = 4$) ``` ((((a + a) + a) + a) + a) ``` Or ``` (+) | \ (+) a |...

BTW: should I expect that the AExpr processing treats expressions with common sub-expressions like DAGs, or like trees (increasing the perceived size?). That is, if I write: ``` expr =...

> It is seen as trees. They are turned into DAGS during execution if CSE recognized it. Thanks. I suspect that means there are (perhaps pathological) cases where expression processing...