[bazel] Use zstd from the BCR

This way if the downstream consuming project uses zstd we make sure
they are dedup'd.

Author: keith

utils/bazel/MODULE.bazel

@@ -22,7 +22,6 @@ use_repo(
     "gmp",
     "llvm-raw",
     "llvm_zlib",
-    "llvm_zstd",
     "mpc",
     "mpfr",
     "nanobind",
@@ -34,6 +33,8 @@ use_repo(
     "vulkan_sdk",
 )
 
+bazel_dep(name = "zstd", version = "1.5.7", repo_name = "llvm_zstd")
+
 llvm_configure = use_repo_rule("@llvm-raw//utils/bazel:configure.bzl", "llvm_configure")
 
 llvm_configure(name = "llvm-project")

utils/bazel/MODULE.bazel.lock

@@ -79,16 +79,6 @@ def _llvm_repos_extension_impl(module_ctx):
         build_file = "@llvm-raw//utils/bazel/third_party_build:pfm.BUILD",
     )
 
-    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",
-        ],
-    )
-
     http_archive(
         name = "pybind11",
         url = "https://github.com/pybind/pybind11/archive/v2.10.3.zip",

utils/bazel/extensions.bzl

@@ -105,8 +105,8 @@ cc_library(
         "//llvm:TargetParser",
         "//llvm:TransformUtils",
         "//llvm:config",
+        "//third_party:zstd",
         "@llvm_zlib//:zlib",
-        "@llvm_zstd//:zstd",
     ],
 )
 

utils/bazel/llvm-project-overlay/lld/BUILD.bazel

@@ -331,7 +331,7 @@ cc_library(
         # We unconditionally depend on the custom LLVM zstd wrapper. This will
         # be an empty library unless zstd is enabled, in which case it will
         # both provide the necessary dependencies and configuration defines.
-        "@llvm_zstd//:zstd",
+        "//third-party:zstd",
     ],
 )
 

utils/bazel/llvm-project-overlay/llvm/BUILD.bazel

@@ -0,0 +1,40 @@
+# This file is licensed under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+load("@bazel_skylib//rules:common_settings.bzl", "bool_flag")
+load("@rules_cc//cc:defs.bzl", "cc_library")
+
+cc_library(name = "empty_lib")
+
+bool_flag(
+    name = "llvm_enable_zstd",
+    build_setting_default = True,
+)
+
+config_setting(
+    name = "llvm_zstd_enabled",
+    flag_values = {":llvm_enable_zstd": "true"},
+)
+
+cc_library(
+    name = "zstd_wrapper",
+    defines = select({
+        ":llvm_zstd_enabled": [
+            "LLVM_ENABLE_ZSTD=1",
+            "ZSTD_MULTITHREAD",
+        ],
+        "//conditions:default": [],
+    }),
+    deps = [
+        "@llvm_zstd//:zstd",
+    ],
+)
+
+alias(
+    name = "zstd",
+    actual = select({
+        ":llvm_zstd_enabled": ":zstd_wrapper",
+        "//conditions:default": ":empty_lib",
+    }),
+    visibility = ["//visibility:public"],
+)