migrate llvm dependency to bazelmod

Author: j2kun

MODULE.bazel

@@ -41,6 +41,37 @@ bazel_dep(name = "rules_shell", version = "0.6.1")
 bazel_dep(name = "re2", version = "2025-08-12")
 bazel_dep(name = "isl", version = "0.27")
 
+# LLVM dependency uses module extensions because none of these are in the BCR
+mlir_tutorial_deps = use_extension("//bazel:extensions.bzl", "llvm_deps")
+use_repo(
+    mlir_tutorial_deps,
+    "llvm-raw",
+    "llvm_zlib",
+    "llvm_zstd",
+)
+
+# The subset of LLVM backend targets that should be compiled
+_LLVM_TARGETS = [
+    "X86",
+    # The bazel dependency graph for mlir-opt fails to load (at the analysis
+    # step) without the NVPTX target in this list, because mlir/test:TestGPU
+    # depends on the //llvm:NVPTXCodeGen target, which is not defined unless this
+    # is included. @j2kun asked the LLVM maintiners for tips on how to fix this,
+    # see https://github.com/llvm/llvm-project/issues/63135
+    "NVPTX",
+    # Needed for Apple M1 targets, see
+    # https://github.com/j2kun/mlir-tutorial/issues/11
+    "AArch64",
+]
+
+# 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",
+    targets = _LLVM_TARGETS,
+)
+
 # Yosys dependencies that are already on the bazel central registry.
 # abc can't be used in place because it changes the names of the targets from
 # abc-lib -> abc and abc -> abc_bin

MODULE.bazel.lock

@@ -2,46 +2,6 @@
 
 load("@bazel_tools//tools/build_defs/repo:git.bzl", "git_repository")
 load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
-load("@bazel_tools//tools/build_defs/repo:utils.bzl", "maybe")
-
-# LLVM is pinned to the same commit used in the Google monorepo, and then
-# imported into this workspace as a git repository. Then the build files
-# defined in the LLVM monorepo are overlaid using llvm_configure in the setup
-# script below. This defines the @llvm-project which is used for llvm build
-# dependencies.
-load("//bazel:import_llvm.bzl", "import_llvm")
-
-import_llvm("llvm-raw")
-
-load("//bazel:setup_llvm.bzl", "setup_llvm")
-
-setup_llvm("llvm-project")
-
-# LLVM doesn't have proper support for excluding the optional llvm_zstd and
-# llvm_zlib dependencies but it is supposed to make LLVM faster, so why not
-# include it.
-# See https://reviews.llvm.org/D143344#4232172
-maybe(
-    http_archive,
-    name = "llvm_zstd",
-    build_file = "@llvm-raw//utils/bazel/third_party_build:zstd.BUILD",
-    sha256 = "7c42d56fac126929a6a85dbc73ff1db2411d04f104fae9bdea51305663a83fd0",
-    strip_prefix = "zstd-1.5.2",
-    urls = [
-        "https://github.com/facebook/zstd/releases/download/v1.5.2/zstd-1.5.2.tar.gz",
-    ],
-)
-
-maybe(
-    http_archive,
-    name = "llvm_zlib",
-    build_file = "@llvm-raw//utils/bazel/third_party_build:zlib-ng.BUILD",
-    sha256 = "e36bb346c00472a1f9ff2a0a4643e590a254be6379da7cddd9daeb9a7f296731",
-    strip_prefix = "zlib-ng-2.0.7",
-    urls = [
-        "https://github.com/zlib-ng/zlib-ng/archive/refs/tags/2.0.7.zip",
-    ],
-)
 
 # install dependencies for yosys/ABC circuit optimizers
 http_archive(

WORKSPACE.bzlmod

@@ -2,18 +2,6 @@
 
 load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
 
-bzl_library(
-    name = "import_llvm_bzl",
-    srcs = ["import_llvm.bzl"],
-    visibility = ["//visibility:private"],
-)
-
-bzl_library(
-    name = "setup_llvm_bzl",
-    srcs = ["setup_llvm.bzl"],
-    visibility = ["//visibility:private"],
-)
-
 bzl_library(
     name = "lit_bzl",
     srcs = ["lit.bzl"],

bazel/BUILD

@@ -0,0 +1,55 @@
+"""Module extensions for MLIR Tutorial dependencies."""
+
+load("@bazel_tools//tools/build_defs/repo:git.bzl", "new_git_repository")
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+load("@bazel_tools//tools/build_defs/repo:utils.bzl", "maybe")
+
+def _llvm_deps_impl(_):
+    """Implementation of the llvm_deps module extension."""
+    LLVM_COMMIT = "8f264586d7521b0e305ca7bb78825aa3382ffef7"
+
+    # Download LLVM/MLIR using a git repository
+    new_git_repository(
+        name = "llvm-raw",
+        build_file_content = "# empty",
+        commit = LLVM_COMMIT,
+        init_submodules = False,
+        remote = "https://github.com/llvm/llvm-project.git",
+        patches = [
+            # This patch file contains changes that are fixed in upstream LLVM
+            # that are (usually) required to build HEIR, but are not included
+            # as of the LLVM_COMMIT hash above (the fixes are still progressing
+            # through the automated integration process). The patch file is
+            # automatically generated, and should not be removed even if empty.
+            "@heir//patches:llvm.patch",
+        ],
+        patch_args = ["-p1"],
+    )
+
+    # Optional LLVM dependencies for performance. Not required but the bazel
+    # build has no way to omit them. See https://reviews.llvm.org/D143344#4232172
+    maybe(
+        http_archive,
+        name = "llvm_zstd",
+        build_file = "@llvm-raw//utils/bazel/third_party_build:zstd.BUILD",
+        sha256 = "7c42d56fac126929a6a85dbc73ff1db2411d04f104fae9bdea51305663a83fd0",
+        strip_prefix = "zstd-1.5.2",
+        urls = [
+            "https://github.com/facebook/zstd/releases/download/v1.5.2/zstd-1.5.2.tar.gz",
+        ],
+    )
+
+    maybe(
+        http_archive,
+        name = "llvm_zlib",
+        build_file = "@llvm-raw//utils/bazel/third_party_build:zlib-ng.BUILD",
+        sha256 = "e36bb346c00472a1f9ff2a0a4643e590a254be6379da7cddd9daeb9a7f296731",
+        strip_prefix = "zlib-ng-2.0.7",
+        urls = [
+            "https://github.com/zlib-ng/zlib-ng/archive/refs/tags/2.0.7.zip",
+        ],
+    )
+
+llvm_deps = module_extension(
+    implementation = _llvm_deps_impl,
+)