Optimization 0-3?

Questions
1

Hey all! New to TVM and looking to get started. Question, as I can’t find it in the documentation explained.

On this page: https://docs.tvm.ai/tutorials/relay_quick_start.html

A bit goes into optimizations, but it’s not explained:

Users can specify the optimization level of the compilation. Currently this value can be 0 to 3

What is 0, what is 1, what is 2, and what is 3? What do these numbers represent?

2

I also have the same question for a long time.

3

By the codes it says, these are the opt_levels here some of the levels are understandable like SimplifyInference,OpFusion,FoldConstant rest there are no documentation about these. any one can refer these

        OPT_PASS_LEVEL = {
            "SimplifyInference": 0,
            "OpFusion": 1,
            "FoldConstant": 2,
            "FoldScaleAxis": 3,
            "AlterOpLayout": 3,
            "CanonicalizeOps": 3,
            "CanonicalizeCast": 3,
            "EliminateCommonSubexpr": 3,
            "CombineParallelConv2D": 4,
            "CombineParallelDense": 4,
            "FastMath": 4
        }