Merge the Merlin heap tracing to top-of-trunk.

runtime/vm/scavenger.cc

Index: runtime/vm/scavenger.cc
diff --git a/runtime/vm/scavenger.cc b/runtime/vm/scavenger.cc
index 8953e7c941d017de6e0169dae2a4f5b00bc5fe5d..7daa940d01dd50b2466ecc36db3bb503eeda1472 100644
--- a/runtime/vm/scavenger.cc
+++ b/runtime/vm/scavenger.cc
@@ -172,6 +172,9 @@ class ScavengerVisitor : public ObjectPointerVisitor {
         // Not a survivor of a previous scavenge. Just copy the object into the
         // to space.
         new_addr = scavenger_->TryAllocate(size);
+        if (HeapTrace::is_enabled()) {
+          heap_->trace()->TraceCopy(raw_addr, new_addr);
+        }
       } else {
         // TODO(iposva): Experiment with less aggressive promotion. For example
         // a coin toss determines if an object is promoted or whether it should
@@ -185,6 +188,9 @@ class ScavengerVisitor : public ObjectPointerVisitor {
           // be traversed later.
           scavenger_->PushToPromotedStack(new_addr);
           bytes_promoted_ += size;
+          if (HeapTrace::is_enabled()) {
+            heap_->trace()->TracePromotion(raw_addr, new_addr);
+          }
         } else if (!scavenger_->had_promotion_failure_) {
           // Signal a promotion failure and set the growth policy for
           // this, and all subsequent promotion allocations, to force
@@ -195,15 +201,24 @@ class ScavengerVisitor : public ObjectPointerVisitor {
           if (new_addr != 0) {
             scavenger_->PushToPromotedStack(new_addr);
             bytes_promoted_ += size;
+            if (HeapTrace::is_enabled()) {
+              heap_->trace()->TracePromotion(raw_addr, new_addr);
+            }
           } else {
             // Promotion did not succeed. Copy into the to space
             // instead.
             new_addr = scavenger_->TryAllocate(size);
+            if (HeapTrace::is_enabled()) {
+              heap_->trace()->TraceCopy(raw_addr, new_addr);
+            }
           }
         } else {
           ASSERT(growth_policy_ == PageSpace::kForceGrowth);
           // Promotion did not succeed. Copy into the to space instead.
           new_addr = scavenger_->TryAllocate(size);
+          if (HeapTrace::is_enabled()) {
+            heap_->trace()->TraceCopy(raw_addr, new_addr);
+          }
         }
       }
       // During a scavenge we always succeed to at least copy all of the
@@ -635,6 +650,8 @@ void Scavenger::Scavenge(bool invoke_api_callbacks, const char* gc_reason) {
   if (FLAG_verbose_gc) {
     OS::PrintErr("Start scavenge for %s collection\n", gc_reason);
   }
+  uword prev_first_obj_start = FirstObjectStart();
+  uword prev_top_addr = *(TopAddress());
   Timer timer(FLAG_verbose_gc, "Scavenge");
   timer.Start();
 
@@ -680,6 +697,10 @@ void Scavenger::Scavenge(bool invoke_api_callbacks, const char* gc_reason) {
     OS::PrintErr(" done.\n");
   }
 
+  if (HeapTrace::is_enabled()) {
+    heap_->trace()->TraceDeathRange(prev_first_obj_start, prev_top_addr);
+  }
+
   count_++;
   // Done scavenging. Reset the marker.
   ASSERT(scavenging_);