[Codegen][Tuner] attr verifier for tuning specs

[bangtianliu]

This PR is relevant to task in #19214: add a discardable attr verifier for entry points iree_codegen.tuning_spec_entrypoint

[kuhar]

Mostly LGTM now

[kuhar]

Have you confirmed that this error gets emitted when the default spec is invalid?

[kuhar]

@bangtianliu can you please reply instead of marking this as resolved? I don't know what the outcome of this is.

[bangtianliu]

Yes, I did check it and fixed the crashes.

[kuhar]

LGTM % one nit

[MaheshRavishankar]

Could you explain a little bit more about what this is trying to verify. I am just trying to fit it within my mental model. Thanks in advance for explaining it to me.

[bangtianliu]

Could you explain a little bit more about what this is trying to verify. I am just trying to fit it within my mental model. Thanks in advance for explaining it to me.

The primary purpose of adding a verifier is to ensure the correctness of all provided tuning specifications, including the default tuning spec, user-provided tuning specs, and the output tuning specs after linking.

Currently, this PR is primarily on verifying:

• If an attribute's name matches kTuningSpecEntrypointAttrName ("iree_codegen.tuning_spec_entrypoint"), the attribute value must be a UnitAttr.
• The constraints related to the signature of transform::NamedSequenceOp

A detailed explanation can be found: https://github.com/iree-org/iree/blob/main/compiler/src/iree/compiler/Codegen/Dialect/Codegen/IR/IREECodegenDialect.cpp#L55

[MaheshRavishankar]

Could you explain a little bit more about what this is trying to verify. I am just trying to fit it within my mental model. Thanks in advance for explaining it to me.

The primary purpose of adding a verifier is to ensure the correctness of all provided tuning specifications, including the default tuning spec, user-provided tuning specs, and the output tuning specs after linking.

Currently, this PR is primarily on verifying:

• If an attribute's name matches kTuningSpecEntrypointAttrName ("iree_codegen.tuning_spec_entrypoint"), the attribute value must be a UnitAttr.

What is the entry point attr name for?

• The constraints related to the signature of transform::NamedSequenceOp

A detailed explanation can be found: https://github.com/iree-org/iree/blob/main/compiler/src/iree/compiler/Codegen/Dialect/Codegen/IR/IREECodegenDialect.cpp#L55

I don't really follow the reason for these constraints

[bangtianliu]

What is the entry point attr name for?
I don't really follow the reason for these constraints

The current tuning design leverages both default and user-provided tuning specs (specifications) to override compiler heuristics and guide dispatch code generation effectively.

The tunning specs are transform dialect libraries and must adhere to a specific format (as outlined in the tuning documentation):

• All tuning spec entry points (named sequence ops) are marked with the iree_codegen.tuning_spec_entrypoint attribute. They have a single argument of type !transform.any_op and return a single value of type !transform.any_op.

Therefore, the entry point attr (name) iree_codegen.tuning_spec_entrypoint is essential for marking named sequence ops in either default or user-provided tuning specs, and these constraints arise directly from the format requirements of named sequence ops.

For more details, please refer to the tuning documentation: https://iree.dev/reference/tuning/.