Update BUILD.gn

arm/build/config/compiler/BUILD.gn

@@ -773,6 +773,24 @@ config("compiler") {
       (is_win || use_custom_libcxx)) {
     cflags += [ "-fcomplete-member-pointers" ]
   }
+  
+  # MLGO specific flags. These flags enable an ML-based inliner trained on
+  # Chrome on Android (arm32) with ThinLTO enabled, optimizing for size.
+  # The "release" ML model is embedded into clang as part of its build.
+  # Currently, the ML inliner is only enabled when targeting Android due to:
+  # a) Android is where size matters the most.
+  # b) MLGO presently has the limitation of only being able to embed one model
+  #    at a time; It is unclear if the embedded model is beneficial for
+  #    non-Android targets.
+  # MLGO is only officially supported on linux.
+  if (use_ml_inliner && is_a_target_toolchain) {
+    assert(
+        is_android && host_os == "linux",
+        "MLGO is currently only supported for targeting Android on a linux host")
+    if (use_thin_lto) {
+      ldflags += [ "-Wl,-mllvm,-enable-ml-inliner=release" ]
+    }
+  }
 
   # Pass the same C/C++ flags to the objective C/C++ compiler.
   cflags_objc += cflags_c
@@ -1519,9 +1537,6 @@ config("default_warnings") {
         # TODO(thakis): https://crbug.com/617318
         # Currently goma can not handle case sensitiveness for windows well.
         cflags += [ "-Wno-nonportable-include-path" ]
-
-        # Warns in ATL headers; see https://crbug.com/1208419.
-        cflags += [ "-Wno-null-pointer-subtraction" ]
       }
 
       cflags += [
@@ -2052,6 +2067,13 @@ config("optimize") {
     # Favor size over speed.
     if (is_clang) {
       cflags = [ "-O3" ] + common_optimize_on_cflags
+
+      if (use_ml_inliner && is_a_target_toolchain) {
+        cflags += [
+          "-mllvm",
+          "-enable-ml-inliner=release",
+        ]
+      }
     } else {
       cflags = [ "-O3" ] + common_optimize_on_cflags
     }