wrongtest-intellif opened a new pull request, #12572:
URL: https://github.com/apache/tvm/pull/12572
Hi, there. The change aims to improve customization experience of TIR
lowering using annotations.
Currently, we have `LowerOpaqueBlock` pass to convert s-tir(schedulable tir
with blocks) to non-stir. All annotations are dropped then except those used by
legacy TE pragma attributes, they are converted to legacy AttrStmt. For example:
```python
# before
for i in range(10, annotations={"pragma_myattr0": 1, "my_attr0": 1}): ....
# after
with T.attr(i, "pragma_myattr0", 1):
for i in range(10): ....
```
This introduce difficulties when we want to leverage schedule phase
annotations in lowering phase.
1. `pragma_` annotations are converted to legacy AttrStmt, which only
accepts `PrimExpr` typed value. But the loop/block annotations before are
originally much flexible, one could use list/dict to encode more rich compile
time hints.
2. Using `AttrStmt` loses the roundtrip property of TIR, thus we fail to
write testcases of lowering pass with friendly before/after script comparations.
3. It is more cohesive to encode annotations just with related IR node (like
`ForNode`). Or else the developers always have to write separate logics
handling attr node and for node.
The change just add a pass configuration `"tir.LowerOpaqueBlock":
{"preserved_annotations": List[str]}}`. For each annotation key value of loop
or block:
1. if key starts with `pragma_`, keep the original behaviour.
2. if key is registered in `preserved_annotations` list, the annotation is
preserved.
3. or else it is dropped.
The alternative may be preserve all annotations without any extra
configuration. But I think current way take the least impact on overall
lowering stream. If we do not add customized pass config into pass context, all
things should be same.
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