[toolchain] Make Os and Oz mutually exclusive.

This change ensures optimization level flags are exclusive, resolving
ambiguity caused by the previous implementation where it expects the last flag
overwrote the optimization level.

Change-Id: I6b372c36ac99eb647f36956934e08fd6cc0e412f
Signed-off-by: Yi-Hsuan Deng <[email protected]>

toolchain/BUILD

@@ -87,26 +87,92 @@ cc_action_type(
     action_name = OT_ACTION_OBJDUMP,
 )
 
+# minsize feature to switch between Os and Oz.
+cc_feature(
+    name = "feat_minsize",
+    feature_name = "minsize",
+)
+
+cc_feature_constraint(
+    name = "constraint_minsize",
+    all_of = [":feat_minsize"],
+)
+
+cc_feature_constraint(
+    name = "constraint_no_minsize",
+    none_of = [":feat_minsize"],
+)
+
+cc_feature_constraint(
+    name = "constraint_minsize_lld",
+    all_of = [
+        ":feat_minsize",
+        ":feat_use_lld",
+    ],
+)
+
 # Built-in Bazel feature enabled for optimized builds.
 cc_feature(
     name = "feat_opt",
     args = [
-        ":opt",
+        ":optsize",
+        ":minsize",
+        ":minsize_inline_cc",
+        ":minsize_inline_ld",
+        ":default_debug_info",
         ":lto",
     ],
     overrides = "@rules_cc//cc/toolchains/features:opt",
 )
 
 cc_args(
-    name = "opt",
+    name = "default_debug_info",
     actions = ["@rules_cc//cc/toolchains/actions:compile_actions"],
     args = [
-        "-Os",
         "-g",
         "-gdwarf-4",
     ],
 )
 
+cc_args(
+    name = "optsize",
+    actions = ["@rules_cc//cc/toolchains/actions:compile_actions"],
+    args = [
+        "-Os",
+    ],
+    requires_any_of = [":constraint_no_minsize"],
+)
+
+cc_args(
+    name = "minsize",
+    actions = ["@rules_cc//cc/toolchains/actions:compile_actions"],
+    args = [
+        "-Oz",
+    ],
+    requires_any_of = [":constraint_minsize"],
+)
+
+# Inline slightly more which is actually smaller.
+cc_args(
+    name = "minsize_inline_cc",
+    actions = ["@rules_cc//cc/toolchains/actions:compile_actions"],
+    args = [
+        "-mllvm",
+        "--inline-threshold=10",
+    ],
+    requires_any_of = [":constraint_minsize_lld"],
+)
+
+cc_args(
+    name = "minsize_inline_ld",
+    actions = ["@rules_cc//cc/toolchains/actions:link_actions"],
+    args = [
+        "-Wl,-mllvm",
+        "-Wl,--inline-threshold=10",
+    ],
+    requires_any_of = [":constraint_minsize_lld"],
+)
+
 # Built-in Bazel feature enabled for debug builds.
 cc_feature(
     name = "feat_dbg",
@@ -126,18 +192,14 @@ cc_args(
 # Built-in Bazel feature for fast builds.
 cc_feature(
     name = "feat_fastbuild",
-    args = [":fastbuild"],
-    overrides = "@rules_cc//cc/toolchains/features:fastbuild",
-)
-
-cc_args(
-    name = "fastbuild",
-    actions = ["@rules_cc//cc/toolchains/actions:compile_actions"],
     args = [
-        "-Os",
-        "-g",
-        "-gdwarf-4",
+        ":optsize",
+        ":minsize",
+        ":minsize_inline_cc",
+        ":minsize_inline_ld",
+        ":default_debug_info",
     ],
+    overrides = "@rules_cc//cc/toolchains/features:fastbuild",
 )
 
 cc_args(
@@ -306,35 +368,6 @@ cc_args(
     args = ["-flto"],
 )
 
-cc_feature(
-    name = "feat_minsize",
-    args = [
-        ":minsize_cc",
-        ":minsize_ld",
-    ],
-    feature_name = "minsize",
-)
-
-cc_args(
-    name = "minsize_cc",
-    actions = ["@rules_cc//cc/toolchains/actions:compile_actions"],
-    args = [
-        "-Oz",
-        # Inline slightly more which is actually smaller.
-        "-mllvm",
-        "--inline-threshold=10",
-    ],
-)
-
-cc_args(
-    name = "minsize_ld",
-    actions = ["@rules_cc//cc/toolchains/actions:link_actions"],
-    args = [
-        "-Wl,-mllvm",
-        "-Wl,--inline-threshold=10",
-    ],
-)
-
 cc_args(
     name = "unique_sections",
     actions = ["@rules_cc//cc/toolchains/actions:compile_actions"],