build: add OpenMP as dependency

Author: batzor

WORKSPACE.bazel

@@ -14,6 +14,10 @@
 
 workspace(name = "zkir")
 
+load("//bazel:zkir_deps.bzl", "zkir_deps")
+
+zkir_deps()
+
 load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 
 LLVM_COMMIT = "f8287f6c373fcf993643dd6f0e30dde304c1be73"

bazel/zkir_deps.bzl

@@ -0,0 +1,8 @@
+"""
+This module configures dependencies for the ZKIR project.
+"""
+
+load("//third_party/omp:omp_configure.bzl", "omp_configure")
+
+def zkir_deps():
+    omp_configure(name = "local_config_omp")

third_party/omp/BUILD.bazel

@@ -0,0 +1,35 @@
+load("@rules_cc//cc:defs.bzl", "cc_library")
+
+package(default_visibility = ["//visibility:public"])
+
+HEADERS = [
+    "omp.h",
+    "ompx.h",
+    "omp-tools.h",
+    "ompt.h",
+]
+
+# NOTE: This is only for macos.
+#       On other platforms openmp should work without local config.
+genrule(
+    name = "link_headers",
+    outs = HEADERS,
+    cmd = """
+      mkdir -p $(@D)/
+      for file in $(OUTS); do
+        file=$${file##*/}
+        ln -sf /opt/homebrew/opt/libomp/include/$$file $(@D)/$$file
+      done
+    """,
+)
+
+cc_library(
+    name = "omp",
+    hdrs = HEADERS,
+    include_prefix = "third_party/omp/include",
+    includes = ["."],
+    linkopts = [
+        "-L/opt/homebrew/opt/libomp/lib",
+        "-lomp",
+    ],
+)

third_party/omp/omp.BUILD

@@ -0,0 +1,10 @@
+"""
+This module configures OpenMP for use with Bazel.
+"""
+
+def _omp_configure_impl(repository_ctx):
+    repository_ctx.symlink(Label("//third_party/omp:omp.BUILD"), "BUILD.bazel")
+
+omp_configure = repository_rule(
+    implementation = _omp_configure_impl,
+)