build tweaks for cfi

build/config/sanitizers/BUILD.gn

Index: build/config/sanitizers/BUILD.gn
diff --git a/build/config/sanitizers/BUILD.gn b/build/config/sanitizers/BUILD.gn
index dddbf2fa49410578aa913c4d82e38e7c749026d6..fac7d51f682451e3493e77a8171903dd7920a9bf 100644
--- a/build/config/sanitizers/BUILD.gn
+++ b/build/config/sanitizers/BUILD.gn
@@ -157,9 +157,13 @@ config("default_sanitizer_ldflags") {
     if (is_cfi && !is_nacl) {
       ldflags += [
         "-fsanitize=cfi-vcall",
-        "-fsanitize=cfi-derived-cast",
-        "-fsanitize=cfi-unrelated-cast",
       ]
+      if (use_cfi_cast) {
+        ldflags += [
+          "-fsanitize=cfi-derived-cast",
+          "-fsanitize=cfi-unrelated-cast",
+        ]
+      }
       if (use_cfi_diag) {
         ldflags += [
           "-fno-sanitize-trap=cfi",
@@ -255,8 +259,14 @@ config("cfi_flags") {
         rebase_path("//tools/cfi/blacklist.txt", root_build_dir)
     cflags += [
       "-fsanitize=cfi-vcall",
-      "-fsanitize=cfi-derived-cast",
-      "-fsanitize=cfi-unrelated-cast",
+    ]
+    if (use_cfi_cast) {
+      cflags += [
+        "-fsanitize=cfi-derived-cast",
+        "-fsanitize=cfi-unrelated-cast",
+      ]
+    }
+    cflags += [
       "-fsanitize-blacklist=$cfi_blacklist_path",
     ]