[TF:XLA] Bump open source llvm revision to r347843

PiperOrigin-RevId: 223414920

tensorflow/workspace.bzl

@@ -472,11 +472,11 @@ def tf_workspace(path_prefix = "", tf_repo_name = ""):
     tf_http_archive(
         name = "llvm",
         build_file = clean_dep("//third_party/llvm:llvm.autogenerated.BUILD"),
-        sha256 = "6c9b98f745b1cf2a9ef34f6220d0f94620ee5c828151924299913f1822cd40d1",
-        strip_prefix = "llvm-9d5ac66dc1ff01dee56354344c9da0879f1bdc36",
+        sha256 = "f4791ba3e166918bca82df34e2f854e8e188d6055888c64cb28743fd43f2d0d7",
+        strip_prefix = "llvm-b2a42b2112a511a5077fd747fb21e45349cff08d",
         urls = [
-            "https://mirror.bazel.build/github.com/llvm-mirror/llvm/archive/9d5ac66dc1ff01dee56354344c9da0879f1bdc36.tar.gz",
-            "https://github.com/llvm-mirror/llvm/archive/9d5ac66dc1ff01dee56354344c9da0879f1bdc36.tar.gz",
+            "https://mirror.bazel.build/github.com/llvm-mirror/llvm/archive/b2a42b2112a511a5077fd747fb21e45349cff08d.tar.gz",
+            "https://github.com/llvm-mirror/llvm/archive/b2a42b2112a511a5077fd747fb21e45349cff08d.tar.gz",
         ],
     )