Restore first frame tick exception in exclusive trees

runtime/vm/profiler_service.cc

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/profiler_service.h"
 
 #include "vm/growable_array.h"
 #include "vm/native_symbol.h"
 #include "vm/object.h"
 #include "vm/os.h"
@@ skipping 1177 matching lines @@
 
       // Walk the sampled PCs.
       for (intptr_t frame_index = 0;
            frame_index < sample->length();
            frame_index++) {
         ASSERT(sample->At(frame_index) != 0);
         intptr_t index =
             GetProfileCodeIndex(sample->At(frame_index), sample->timestamp());
         ASSERT(index >= 0);
         current = current->GetChild(index);
-        current->Tick();
+        if (ShouldTickNode(sample, frame_index)) {
+          current->Tick();
+        }
       }
-
       // Truncated tag.
       if (sample->truncated()) {
         current = AppendTruncatedTag(current);
       }
     }
   }
 
   void BuildFunctionTrie(Profile::TrieKind kind) {
     ProfileFunctionTrieNode* root =
         new ProfileFunctionTrieNode(
@@ skipping 143 matching lines @@
     ProfileFunction* function = function_table->LookupOrAdd(*inlined_function);
     ASSERT(function != NULL);
     return ProcessFunction(current,
                            sample_index,
                            sample,
                            frame_index,
                            function,
                            code_index);
   }
 
+  bool ShouldTickNode(ProcessedSample* sample, intptr_t frame_index) {
+    if (frame_index != 0) {
+      return true;
+    }
+    // Only tick the first frame's node, if we are executing OR
+    // vm tags have been emitted.
+    return IsExecutingFrame(sample, frame_index) || vm_tags_emitted();
+  }
+
   ProfileFunctionTrieNode* ProcessFunction(ProfileFunctionTrieNode* current,
                                            intptr_t sample_index,
                                            ProcessedSample* sample,
                                            intptr_t frame_index,
                                            ProfileFunction* function,
                                            intptr_t code_index) {
     if (tick_functions_) {
       function->Tick(IsExecutingFrame(sample, frame_index), sample_index);
     }
     function->AddProfileCode(code_index);
     current = current->GetChild(function->table_index());
+    if (ShouldTickNode(sample, frame_index)) {
+      current->Tick();
+    }
     current->AddCodeObjectIndex(code_index);
-    current->Tick();
     return current;
   }
 
   // Tick the truncated tag's inclusive tick count.
   void InclusiveTickTruncatedTag() {
     ProfileCodeTable* tag_table = profile_->tag_code_;
     intptr_t index = tag_table->FindCodeIndexForPC(VMTag::kTruncatedTagId);
     ASSERT(index >= 0);
     ProfileCode* code = tag_table->At(index);
     code->IncInclusiveTicks();
@@ skipping 700 matching lines @@
   ASSERT(sample_buffer != NULL);
 
   ClearProfileVisitor clear_profile(isolate);
   sample_buffer->VisitSamples(&clear_profile);
 
   // Enable profile interrupts.
   Profiler::BeginExecution(isolate);
 }
 
 }  // namespace dart