[vm] Remove traces of LLVM backend

The code has been dead for quite some time.

TEST=ci

Change-Id: Iddcb63e14e9e4d95230f006ac05da64f444f0712
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/190024
Commit-Queue: Vyacheslav Egorov <vegorov@google.com>
Reviewed-by: Siva Annamalai <asiva@google.com>

.gitignore

@@ -23,11 +23,6 @@
 /*.vcxproj.user
 *.stamp
 
-# LLVM prebuilts
-/third_party/llvm/include
-/third_party/llvm/lib
-/third_party/llvm/.versions
-
 # Gyp generated files
 *.xcodeproj
 *.intermediate

BUILD.gn

@@ -14,9 +14,6 @@ group("default") {
     testonly = true
   }
   deps = [ ":runtime" ]
-  if (defined(checkout_llvm) && checkout_llvm) {
-    deps += [ ":llvm_codegen" ]
-  }
 }
 
 group("most") {
@@ -117,21 +114,6 @@ group("analysis_server") {
   deps = [ "utils/analysis_server" ]
 }
 
-group("check_llvm") {
-  if (defined(checkout_llvm) && checkout_llvm) {
-    deps = [ "runtime/llvm_codegen/test" ]
-  }
-}
-
-group("llvm_codegen") {
-  if (defined(checkout_llvm) && checkout_llvm) {
-    deps = [
-      "runtime/llvm_codegen/bit",
-      "runtime/llvm_codegen/codegen",
-    ]
-  }
-}
-
 # This is the target that is built on the dart2js build bots.
 # It must depend on anything that is required by the dart2js
 # test suites.

DEPS

@@ -180,18 +180,10 @@ vars = {
   "chrome_tag": "84",
   "download_firefox": False,
   "firefox_tag": "67",
-
-  # An LLVM backend needs LLVM binaries and headers. To avoid build time
-  # increases we can use prebuilts. We don't want to download this on every
-  # CQ/CI bot nor do we want the average Dart developer to incur that cost.
-  # So by default we will not download prebuilts.
-  "checkout_llvm": False,
-  "llvm_revision": "fe8bd96ebd6c490ea0b5c1fb342db2d7c393a109"
 }
 
 gclient_gn_args_file = Var("dart_root") + '/build/config/gclient_args.gni'
 gclient_gn_args = [
-  'checkout_llvm'
 ]
 
 deps = {
@@ -615,16 +607,6 @@ deps = {
       ],
       "dep_type": "cipd",
   },
-  Var("dart_root") + "/third_party/llvm": {
-      "packages": [
-          {
-              "package": "fuchsia/lib/llvm/${{platform}}",
-              "version": "git_revision:" + Var("llvm_revision"),
-          },
-      ],
-      "condition": "checkout_llvm",
-      "dep_type": "cipd",
-  },
   Var("dart_root") + "/third_party/browsers/chrome": {
       "packages": [
           {

runtime/bin/BUILD.gn

@@ -897,9 +897,6 @@ executable("run_vm_tests") {
     "..:libdart_precompiler",
     "//third_party/zlib",
   ]
-  if (defined(checkout_llvm) && checkout_llvm) {
-    deps += [ "//runtime/llvm_codegen/bit:test" ]
-  }
   include_dirs = [
     "..",
     "$target_gen_dir",