2023-07-25 11:14:16 -07:00
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# MLIR Release Notes
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This document tries to provide some context about MLIR important changes in the
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context of LLVM releases. It is updated on a best effort basis.
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At the moment the MLIR community does not qualify the LLVM release branch
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specifically, it is a snapshot of the MLIR development at the time of the release.
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2023-07-25 17:31:53 -07:00
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[TOC]
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2023-07-25 11:14:16 -07:00
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## LLVM 17
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See also the [deprecations and refactoring](https://mlir.llvm.org/deprecation/) doc.
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### Bytecode
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MLIR now support a [bytecode serialization](https://mlir.llvm.org/docs/BytecodeFormat/)
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with versionning compatibility allowing 2 ways compatibility scheme, and lazy-loading
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capabilities.
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### Properties: beyond attributes
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This is a new mechanism to implement storage for operations without having to
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use attributes. You can opt-in to use Properties for ODS inherent attributes
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using `let usePropertiesForAttributes = 1;` in your dialect definition (the flag
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will be default in the next release). See
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[slides](https://mlir.llvm.org/OpenMeetings/2023-02-09-Properties.pdf) and
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[recording](https://youtu.be/7ofnlCFzlqg) of the open meeting presentation for
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details.
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### Action: Tracing and Debugging MLIR-based Compilers
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[Action](https://mlir.llvm.org/docs/ActionTracing/) is a new mechanism to
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encapsulate any transformation of any granularity in a way that can be
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intercepted by the framework for debugging or tracing purposes, including
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skipping a transformation programmatically (think about “compiler fuel” or
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“debug counters” in LLVM). As such, “executing a pass” is an Action, so is “try
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to apply one canonicalization pattern”, or “tile this loop”.
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[slides](https://mlir.llvm.org/OpenMeetings/2023-02-23-Actions.pdf) and
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[recording](https://youtu.be/ayQSyekVa3c) of the open meeting presentation for
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details.
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### Transform Dialect
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See this [EuroLLVM talk](https://www.youtube.com/watch?v=P4gUj3QtH_Y&t=1s) and
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[the online tutorial](https://mlir.llvm.org/docs/Tutorials/transform/).
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### Others
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- There is now support for
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"[distinct attributes](https://mlir.llvm.org/docs/Dialects/Builtin/#distinctattribute)".
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- "Resources" (a way to store data outside the MLIR context) and "configuration"
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can now be serialized alongside the IR.
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