Bump Bazel version to 8.3.1 and migrate to bzlmod

Author: SihaoLiu

.bazelrc

@@ -1,4 +1,11 @@
+# Enable Bzlmod for every Bazel command
+common --enable_bzlmod
+
+# Original configurations
 common --action_env=BAZEL_CXXOPTS=-std=c++17
+build --action_env=CCACHE_DISABLE=1
+build --action_env=CC=/usr/bin/gcc
+build --action_env=CXX=/usr/bin/g++
 common --cxxopt='-std=c++17'
 common --deleted_packages=externals
 build:macos --apple_platform_type=macos
@@ -8,3 +15,51 @@ build:macos_arm64 --cpu=darwin_arm64
 common --copt=-fdiagnostics-color=always
 common --test_output=errors
 common -c dbg
+
+# Additional optimizations for C++ compilation
+# Note: boost.thread requires exceptions, boost.serialization requires RTTI
+build --cxxopt=-fexceptions
+# Disabled RTTI as some boost components need it
+# build --cxxopt=-fno-rtti
+
+# GNU source compatibility
+build --cxxopt=-D_GNU_SOURCE
+build --cxxopt=-D__STDC_CONSTANT_MACROS
+build --cxxopt=-D__STDC_FORMAT_MACROS
+build --cxxopt=-D__STDC_LIMIT_MACROS
+
+# Debug build configuration (similar to CMAKE_BUILD_TYPE=DEBUG)
+build:debug --cxxopt=-g
+build:debug --cxxopt=-O0
+build:debug --strip=never
+build:debug --copt=-DDEBUG
+
+# Release build configuration (similar to CMAKE_BUILD_TYPE=RELEASE)  
+build:release --cxxopt=-O3
+build:release --cxxopt=-DNDEBUG
+build:release --strip=always
+
+# Build with assertions enabled (similar to LLVM_ENABLE_ASSERTIONS=ON)
+build:assertions --cxxopt=-UNDEBUG
+build:assertions --cxxopt=-DMLIR_ENABLE_ASSERTIONS
+
+# Verbose output (similar to ninja -v)
+build:verbose --subcommands=pretty_print
+build:verbose --verbose_failures
+
+# Parallel build (similar to ninja -j)
+build --jobs=auto
+
+# Test configuration
+test --test_output=errors
+test --test_summary=short
+
+# Cache configuration, disable ccache since bazel cache system is much better
+build --disk_cache=~/.cache/bazel
+build --repository_cache=~/.cache/bazel/repo
+
+# Compatibility settings
+build --incompatible_enable_cc_toolchain_resolution
+
+# Sandbox Location configuration
+build --sandbox_base=/dev/shm

.bazelversion

@@ -1 +1 @@
-6.4.0
+8.3.1

.gitignore

@@ -3,6 +3,7 @@ bazel-bin
 bazel-mlir-tutorial
 bazel-out
 bazel-testlogs
+MODULE.bazel.lock
 
 # cmake related files
 # ignore the user specified CMake presets in subproject directories.

CLAUDE.md

@@ -0,0 +1,88 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Project Overview
+
+This is an MLIR (Multi-Level Intermediate Representation) tutorial codebase demonstrating compiler construction concepts. The project implements custom MLIR dialects and passes, with comprehensive examples showing how to build compiler transformations.
+
+## Build Systems
+
+The project supports two build systems:
+
+### Bazel (Primary)
+- **Version**: Bazel 8.3.1 with Bzlmod enabled
+- **Dependency Management**: Uses MODULE.bazel with Bazel Central Registry (BCR)
+- **Build all**: `bazel build ...:all`
+- **Test all**: `bazel test ...:all`
+- **Build specific target**: `bazel build //tools:tutorial-opt`
+- **Test specific target**: `bazel test //tests:poly_syntax`
+
+#### Bzlmod Migration
+The project has been migrated from WORKSPACE-based dependency management to Bzlmod:
+- **MODULE.bazel**: Main module definition with dependencies from BCR
+- **extensions.bzl**: Custom module extension for LLVM-related dependencies
+- **WORKSPACE**: Simplified to workspace name only
+- Most dependencies (rules_python, protobuf, or-tools, etc.) now use BCR
+- LLVM dependencies still use git repositories for latest upstream integration
+
+### CMake (Secondary)
+First build LLVM/MLIR dependencies, then:
+- **Configure**: `cmake -G Ninja -DLLVM_DIR="externals/llvm-project/build/lib/cmake/llvm" -DMLIR_DIR="externals/llvm-project/build/lib/cmake/mlir" -DBUILD_DEPS=ON -DCMAKE_BUILD_TYPE=Debug .`
+- **Build main tool**: `cmake --build build-ninja --target tutorial-opt`
+- **Run tests**: `cmake --build build-ninja --target check-mlir-tutorial`
+
+## Key Architecture
+
+### Core Components
+- **tutorial-opt**: Main compiler tool in `tools/tutorial-opt.cpp` - processes MLIR files through various passes
+- **Custom Dialects**: 
+  - `Poly`: Polynomial arithmetic dialect (`lib/Dialect/Poly/`)
+  - `Noisy`: Demonstration dialect with noise operations (`lib/Dialect/Noisy/`)
+- **Transforms**: Located in `lib/Transform/` with subdirectories for different pass categories
+- **Conversions**: Dialect lowering passes in `lib/Conversion/`
+- **Analysis**: Data flow analysis passes in `lib/Analysis/`
+
+### Test Infrastructure
+- Uses LLVM's `lit` testing framework
+- Test files in `tests/` directory with `.mlir` extension
+- Run individual tests: `bazel test //tests:test_name`
+
+### Pass Pipeline
+The `poly-to-llvm` pipeline demonstrates full lowering:
+1. Poly dialect → Standard dialect
+2. Standard → Linalg
+3. Bufferization
+4. Linalg → Loops
+5. Loops → Control Flow
+6. Control Flow → LLVM IR
+
+## Development Commands
+
+### Testing Individual Components
+- **Syntax test**: `tutorial-opt tests/poly_syntax.mlir`
+- **Canonicalization**: `tutorial-opt --canonicalize tests/poly_canonicalize.mlir`
+- **Full lowering**: `tutorial-opt --poly-to-llvm tests/poly_to_llvm.mlir`
+
+### Adding New Passes
+1. Define in appropriate `lib/Transform/*/Passes.td`
+2. Implement in corresponding `.cpp` file
+3. Register in `tools/tutorial-opt.cpp`
+4. Add test in `tests/`
+
+### Tablegen Files
+- Dialect definitions: `*.td` files in `lib/Dialect/*/`
+- Pass definitions: `Passes.td` files in `lib/Transform/*/`
+- Pattern definitions: `*.td` files for rewrite patterns
+
+## File Structure
+- `lib/`: Core implementation (dialects, passes, conversions, analysis)
+- `tools/`: Command-line tools (mainly tutorial-opt)
+- `tests/`: Test files using lit framework
+- `bazel/`: Bazel build configuration (legacy, LLVM import utilities)
+- `externals/`: LLVM/MLIR submodule (for CMake builds)
+- `MODULE.bazel`: Bzlmod module definition with BCR dependencies
+- `extensions.bzl`: Custom module extension for LLVM dependencies
+- `WORKSPACE`: Simplified workspace marker (legacy dependencies removed)
+- `.bazelversion`: Pins Bazel version to 8.3.1
+- `.bazelrc`: Build configuration with Bzlmod enabled

MODULE.bazel

@@ -0,0 +1,70 @@
+###############################################################################
+# Bazel now uses Bzlmod by default to manage external dependencies.
+# Please consider migrating your external dependencies from WORKSPACE to MODULE.bazel.
+#
+# For more details, please check https://github.com/bazelbuild/bazel/issues/18958
+###############################################################################
+
+module(
+    name = "mlir_tutorial",
+    version = "1.0.0",
+    repo_name = "mlir_tutorial",
+)
+
+# Core Bazel dependencies that are available in BCR
+bazel_dep(name = "bazel_skylib", version = "1.7.1")
+bazel_dep(name = "rules_python", version = "1.2.0")
+bazel_dep(name = "platforms", version = "0.0.11")
+bazel_dep(name = "rules_cc", version = "0.1.1")
+bazel_dep(name = "rules_java", version = "8.12.0")
+bazel_dep(name = "protobuf", version = "30.1")
+bazel_dep(name = "rules_proto", version = "7.1.0")
+bazel_dep(name = "rules_pkg", version = "1.1.0")
+
+# External dependencies available in BCR
+bazel_dep(name = "re2", version = "2024-07-02.bcr.1")
+bazel_dep(name = "abseil-cpp", version = "20250512.1")
+bazel_dep(name = "or-tools", version = "9.12")
+bazel_dep(name = "eigen", version = "4.0.0-20241125.bcr.2")
+bazel_dep(name = "highs", version = "1.11.0")
+bazel_dep(name = "pcre2", version = "10.46-DEV")
+bazel_dep(name = "glpk", version = "5.0.bcr.4")
+bazel_dep(name = "bliss", version = "0.73")
+bazel_dep(name = "scip", version = "9.2.0.bcr.3")
+bazel_dep(name = "zlib-ng", version = "2.0.7")
+
+# Hedron's Compile Commands Extractor for Bazel
+# https://github.com/hedronvision/bazel-compile-commands-extractor
+bazel_dep(name = "hedron_compile_commands", dev_dependency = True)
+git_override(
+    module_name = "hedron_compile_commands",
+    remote = "https://github.com/hedronvision/bazel-compile-commands-extractor.git",
+    commit = "0e990032f3c5a866e72615cf67e5ce22186dcb97",
+    # Replace the commit hash (above) with the latest (https://github.com/hedronvision/bazel-compile-commands-extractor/commits/main).
+    # Even better, set up Renovate and let it do the work for you (see "Suggestion: Updates" in the README).
+)
+
+# Use module extensions for LLVM and other dependencies that aren't in BCR
+mlir_tutorial_deps = use_extension("//:extensions.bzl", "mlir_tutorial_deps")
+use_repo(mlir_tutorial_deps, 
+    "llvm-raw", 
+    "llvm_zstd", 
+    "llvm_zlib"
+)
+
+# Configure LLVM project using use_repo_rule
+llvm_configure = use_repo_rule("@llvm-raw//utils/bazel:configure.bzl", "llvm_configure")
+llvm_configure(name = "llvm-project")
+
+# Configure Python dependencies
+python = use_extension("@rules_python//python/extensions:python.bzl", "python")
+python.toolchain(python_version = "3.10")
+use_repo(python, "python_3_10")
+
+pip = use_extension("@rules_python//python/extensions:pip.bzl", "pip")
+pip.parse(
+    hub_name = "mlir_tutorial_pip_deps",
+    python_version = "3.10",
+    requirements_lock = "//:requirements.txt",
+)
+use_repo(pip, "mlir_tutorial_pip_deps") 

README.md

@@ -30,6 +30,11 @@ the tutorial series and explained in the first article,
 The CMake build is maintained, but was added at article 10 (Dialect Conversion)
 and will not be explained in the articles.
 
+**Note**: This project has been upgraded to Bazel 8.3.1 and migrated to use 
+Bzlmod for dependency management, replacing the traditional WORKSPACE file 
+approach. Dependencies are now managed through `MODULE.bazel` using the 
+Bazel Central Registry (BCR) where possible.
+
 ### Prerequisites
 
 Install Bazelisk via instructions at
@@ -39,6 +44,9 @@ This should create the `bazel` command on your system.
 You should also have a modern C++ compiler on your system, either `gcc` or
 `clang`, which Bazel will detect.
 
+**Bazel Version**: This project requires Bazel 8.3.1 or newer. The specific
+version is pinned in `.bazelversion`.
+
 ### Build and test
 
 Run
@@ -48,6 +56,19 @@ bazel build ...:all
 bazel test ...:all
 ```
 
+### Dependency Management
+
+The project uses Bzlmod (MODULE.bazel) for dependency management:
+
+- **Core dependencies**: Managed through Bazel Central Registry (BCR)
+  - rules_python, rules_java, protobuf, abseil-cpp, or-tools, etc.
+- **LLVM dependencies**: Managed through custom module extension
+  - LLVM/MLIR source code via git repository
+- **Development tools**: hedron_compile_commands via git_override
+
+This approach provides better dependency resolution, versioning, and 
+compatibility compared to the legacy WORKSPACE approach.
+
 ## CMake build
 
 CMake is one of two supported build systems for this tutorial. The other is