heap: Inline GCTracer::Scope::Name

This is a follow-up to https://crrev.com/c/3581774.
It inlines method GCTracer::Scope::Name so that the calculation of the
name of the trace event can be performed at compile time and optimized
away, at most call sites.

This is a reland of 370cae1d
which was reviewed here: https://crrev.com/c/3602511

Bug: chromium:1318062
Change-Id: I617fcad07448ebbd63790600a071e51964baf85c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3605811Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Nikolaos Papaspyrou <nikolaos@chromium.org>
Reviewed-by: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80231}

src/heap/gc-tracer-inl.h

@@ -77,6 +77,31 @@ GCTracer::Scope::~Scope() {
 #endif  // defined(V8_RUNTIME_CALL_STATS)
 }
 
+constexpr const char* GCTracer::Scope::Name(ScopeId id) {
+#define CASE(scope)  \
+  case Scope::scope: \
+    return "V8.GC_" #scope;
+  switch (id) {
+    TRACER_SCOPES(CASE)
+    TRACER_BACKGROUND_SCOPES(CASE)
+    default:
+      return nullptr;
+  }
+#undef CASE
+}
+
+constexpr bool GCTracer::Scope::NeedsYoungEpoch(ScopeId id) {
+#define CASE(scope)  \
+  case Scope::scope: \
+    return true;
+  switch (id) {
+    TRACER_YOUNG_EPOCH_SCOPES(CASE)
+    default:
+      return false;
+  }
+#undef CASE
+}
+
 constexpr int GCTracer::Scope::IncrementalOffset(ScopeId id) {
   DCHECK_LE(FIRST_INCREMENTAL_SCOPE, id);
   DCHECK_GE(LAST_INCREMENTAL_SCOPE, id);

src/heap/gc-tracer.cc

@@ -58,33 +58,6 @@ void GCTracer::Scope::AssertMainThread() {
 }
 #endif  // DEBUG
 
-const char* GCTracer::Scope::Name(ScopeId id) {
-#define CASE(scope)  \
-  case Scope::scope: \
-    return "V8.GC_" #scope;
-  switch (id) {
-    TRACER_SCOPES(CASE)
-    TRACER_BACKGROUND_SCOPES(CASE)
-    case Scope::NUMBER_OF_SCOPES:
-      break;
-  }
-#undef CASE
-  UNREACHABLE();
-}
-
-bool GCTracer::Scope::NeedsYoungEpoch(ScopeId id) {
-#define CASE(scope)  \
-  case Scope::scope: \
-    return true;
-  switch (id) {
-    TRACER_YOUNG_EPOCH_SCOPES(CASE)
-    default:
-      return false;
-  }
-#undef CASE
-  UNREACHABLE();
-}
-
 GCTracer::Event::Event(Type type, State state,
                        GarbageCollectionReason gc_reason,
                        const char* collector_reason)

src/heap/gc-tracer.h

@@ -97,9 +97,9 @@ class V8_EXPORT_PRIVATE GCTracer {
     V8_INLINE ~Scope();
     Scope(const Scope&) = delete;
     Scope& operator=(const Scope&) = delete;
-    static const char* Name(ScopeId id);
-    static bool NeedsYoungEpoch(ScopeId id);
-    V8_INLINE static constexpr int IncrementalOffset(ScopeId id);
+    static constexpr const char* Name(ScopeId id);
+    static constexpr bool NeedsYoungEpoch(ScopeId id);
+    static constexpr int IncrementalOffset(ScopeId id);
 
    private:
 #if DEBUG