[QST] [CuTeDSL] `fastmath` ignored?

[HanGuo97]

What is your question?

Is it intentional that fastmath argument is ignored in cute.math

[fengxie]

Yes, the reason is fast math flag is a bit complicated: https://mlir.llvm.org/docs/Dialects/MathOps/#fastmathflags

We feel need some time to figure out right way to expose. (Working on some partial solution). But users can temporarily wire them to get what you want.

[HanGuo97]

Gotcha, thank you!

On a unrelated question. For wrappers around PTX, when should we set has_side_effects=True vs has_side_effects=False? It looks like everywhere inline_asm is used, it was set to True, including for exp2.

[fengxie]

Gotcha, thank you!

On a unrelated question. For wrappers around PTX, when should we set has_side_effects=True vs has_side_effects=False? It looks like everywhere inline_asm is used, it was set to True, including for exp2.

It's better to set has_side_effects=False for operations don't really have side-effects e.g. memory load/store, barrier, etc. It should be safe to use has_side_effects=False for math ops. This allows compiler to do some optimization.

[HanGuo97]

Got it, thanks again!