Moves the top_ and end_ words of the Scavenger into mutator thread.

runtime/vm/scavenger.h

Index: runtime/vm/scavenger.h
diff --git a/runtime/vm/scavenger.h b/runtime/vm/scavenger.h
index 82e9adc4badf3b5f1eb2aa1aac4a89cf24f4eaf0..1fd7c9fe2bd88b93e8f26e2c6b7964e11a0408bc 100644
--- a/runtime/vm/scavenger.h
+++ b/runtime/vm/scavenger.h
@@ -121,24 +121,46 @@ class Scavenger {
 
   RawObject* FindObject(FindObjectVisitor* visitor) const;
 
-  uword TryAllocate(intptr_t size) {
+  uword AllocateGC(intptr_t size) {
     ASSERT(Utils::IsAligned(size, kObjectAlignment));
     ASSERT(heap_ != Dart::vm_isolate()->heap());
+    ASSERT(scavenging_);
+    uword result = top_;
+    intptr_t remaining = end_ - top_;
+
+    // This allocation happens only in GC and only when copying objects to
+    // the new to_ space. It must succeed.
+    ASSERT(size <= remaining);
+    ASSERT(to_->Contains(result));
+    ASSERT((result & kObjectAlignmentMask) == object_alignment_);
+    top_ += size;
+    ASSERT(to_->Contains(top_) || (top_ == to_->end()));
+    return result;
+  }
+
+  uword TryAllocateInTLAB(Thread* thread, intptr_t size) {
+    ASSERT(Utils::IsAligned(size, kObjectAlignment));
+    ASSERT(heap_ != Dart::vm_isolate()->heap());
+    ASSERT(thread->IsMutatorThread());
+    ASSERT(thread->isolate()->IsMutatorThreadScheduled());
 #if defined(DEBUG)
-    if (FLAG_gc_at_alloc && !scavenging_) {
+    if (FLAG_gc_at_alloc) {
+      ASSERT(!scavenging_);
       Scavenge();
     }
 #endif
-    uword result = top_;
-    intptr_t remaining = end_ - top_;
+    uword top = thread->top();
+    uword end = thread->end();
+    uword result = top;
+    intptr_t remaining = end - top;
     if (remaining < size) {
       return 0;
     }
     ASSERT(to_->Contains(result));
     ASSERT((result & kObjectAlignmentMask) == object_alignment_);
-
-    top_ += size;
-    ASSERT(to_->Contains(top_) || (top_ == to_->end()));
+    top += size;
+    ASSERT(to_->Contains(top) || (top == to_->end()));
+    thread->set_top(top);
     return result;
   }
 
@@ -149,11 +171,14 @@ class Scavenger {
   // Promote all live objects.
   void Evacuate();
 
-  // Accessors to generate code for inlined allocation.
-  uword* TopAddress() { return &top_; }
-  uword* EndAddress() { return &end_; }
-  static intptr_t top_offset() { return OFFSET_OF(Scavenger, top_); }
-  static intptr_t end_offset() { return OFFSET_OF(Scavenger, end_); }
+  uword top() { return top_; }
+  uword end() { return end_; }
+
+  void set_top(uword value) { top_ = value; }
+  void set_end(uword value) {
+    ASSERT(to_->end() == value);
+    end_ = value;
+  }
 
   int64_t UsedInWords() const {
     return (top_ - FirstObjectStart()) >> kWordSizeLog2;
@@ -190,6 +215,8 @@ class Scavenger {
   void AllocateExternal(intptr_t size);
   void FreeExternal(intptr_t size);
 
+  void FlushTLS() const;
+
  private:
   // Ids for time and data records in Heap::GCStats.
   enum {
@@ -252,12 +279,6 @@ class Scavenger {
 
   intptr_t NewSizeInWords(intptr_t old_size_in_words) const;
 
-  // Accessed from generated code.
-  // ** This block of fields must come first! **
-  // For AOT cross-compilation, we rely on these members having the same offsets
-  // in SIMARM(IA32) and ARM, and the same offsets in SIMARM64(X64) and ARM64.
-  // We use only word-sized fields to avoid differences in struct packing on the
-  // different architectures. See also CheckOffsets in dart.cc.
   uword top_;
   uword end_;