Add checks for stack-allocated types and their uses in fields.

tools/clang/blink_gc_plugin/RecordInfo.cpp

Index: tools/clang/blink_gc_plugin/RecordInfo.cpp
diff --git a/tools/clang/blink_gc_plugin/RecordInfo.cpp b/tools/clang/blink_gc_plugin/RecordInfo.cpp
index 9072d0340ef327bcea54591863a343bd4f6c112f..6fa2474b40a387fec1d5a9a49b7c67cc4eb5a440 100644
--- a/tools/clang/blink_gc_plugin/RecordInfo.cpp
+++ b/tools/clang/blink_gc_plugin/RecordInfo.cpp
@@ -17,6 +17,7 @@ RecordInfo::RecordInfo(CXXRecordDecl* record, RecordCache* cache)
       fields_need_tracing_(TracingStatus::Unknown()),
       bases_(0),
       fields_(0),
+      is_stack_allocated_(kMaybe),

[Mads Ager (chromium), 2014/03/20 10:32:29]

Wasn't it called kNone in the enum? This is really a cache and maybe we should
name it accordingly?

enum CachedBool {
  kFalse = 0,
  kTrue = 1,
  kNotComputed = 2
};

[zerny-chromium, 2014/03/20 15:14:20]

Done.

       determined_trace_methods_(false),
       trace_method_(0),
       trace_dispatch_method_(0),
@@ -151,17 +152,26 @@ RecordInfo* RecordCache::Lookup(CXXRecordDecl* record) {
 }
 
 bool RecordInfo::IsStackAllocated() {
-  for (CXXRecordDecl::method_iterator it = record_->method_begin();
-       it != record_->method_end();
-       ++it) {
-    if (it->getNameAsString() == kNewOperatorName)
-      return it->isDeleted() && IsAnnotated(*it, "blink_stack_allocated");
+  if (is_stack_allocated_ == kNone) {
+    is_stack_allocated_ = kFalse;
+    for (CXXRecordDecl::method_iterator it = record_->method_begin();
+         it != record_->method_end();
+         ++it) {
+      if (it->getNameAsString() == kNewOperatorName) {
+        if (it->isDeleted() && IsAnnotated(*it, "blink_stack_allocated")) {
+          is_stack_allocated_ = kTrue;
+          break;
+        }
+      }
+    }
   }
-  return false;
+  return is_stack_allocated_;
 }
 
 // An object requires a tracing method if it has any fields that need tracing.
 bool RecordInfo::RequiresTraceMethod() {
+  if (IsStackAllocated())
+    return false;
   GetFields();
   return fields_need_tracing_.IsNeeded();
 }