Sub-channel quantized type implementation (#120172) This is an implementation for [RFC: Supporting Sub-Channel Quantization in MLIR](https://discourse.llvm.org/t/rfc-supporting-sub-channel-quantization-in-mlir/82694). In order to make the review process easier, the PR has been divided into the following commit labels: 1. **Add implementation for sub-channel type:** Includes the class design for `UniformQuantizedSubChannelType`, printer/parser and bytecode read/write support. The existing types (per-tensor and per-axis) are unaltered. 2. **Add implementation for sub-channel type:** Lowering of `quant.qcast` and `quant.dcast` operations to Linalg operations. 3. **Adding C/Python Apis:** We first define he C-APIs and build the Python-APIs on top of those. 4. **Add pass to normalize generic ....:** This pass normalizes sub-channel quantized types to per-tensor per-axis types, if possible. A design note: - **Explicitly storing the `quantized_dimensions`, even when they can be derived for ranked tensor.** While it's possible to infer quantized dimensions from the static shape of the scales (or zero-points) tensor for ranked data tensors ([ref](https://discourse.llvm.org/t/rfc-supporting-sub-channel-quantization-in-mlir/82694/3) for background), there are cases where this can lead to ambiguity and issues with round-tripping. ``` Consider the example: tensor<2x4x!quant.uniform<i8:f32:{0:2, 0:2}, {{s00:z00, s01:z01}}>> ``` The shape of the scales tensor is [1, 2], which might suggest that only axis 1 is quantized. While this inference is technically correct, as the block size for axis 0 is a degenerate case (equal to the dimension size), it can cause problems with round-tripping. Therefore, even for ranked tensors, we are explicitly storing the quantized dimensions. Suggestions welcome! PS: I understand that the upcoming holidays may impact your schedule, so please take your time with the review. There's no rush.
Welcome to the LLVM project!
This repository contains the source code for LLVM, a toolkit for the construction of highly optimized compilers, optimizers, and run-time environments.
The LLVM project has multiple components. The core of the project is itself called “LLVM”. This contains all of the tools, libraries, and header files needed to process intermediate representations and convert them into object files. Tools include an assembler, disassembler, bitcode analyzer, and bitcode optimizer.
C-like languages use the Clang frontend. This component compiles C, C++, Objective-C, and Objective-C++ code into LLVM bitcode -- and from there into object files, using LLVM.
Other components include: the libc++ C++ standard library, the LLD linker, and more.
Consult the Getting Started with LLVM page for information on building and running LLVM.
For information on how to contribute to the LLVM project, please take a look at the Contributing to LLVM guide.
Join the LLVM Discourse forums, Discord chat, LLVM Office Hours or Regular sync-ups.
The LLVM project has adopted a code of conduct for participants to all modes of communication within the project.