Update Assembler::TryAllocate to support inline allocation tracing

runtime/vm/assembler_arm64.cc

 // Copyright (c) 2014, 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/globals.h"  // NOLINT
 #if defined(TARGET_ARCH_ARM64)
 
 #include "vm/assembler.h"
 #include "vm/cpu.h"
 #include "vm/longjump.h"
@@ skipping 1304 matching lines @@
     ldr(TMP, Address(TMP2, count_field_offset));
     AddImmediate(TMP, TMP, 1, pp);
     str(TMP, Address(TMP2, count_field_offset));
     ldr(TMP, Address(TMP2, size_field_offset));
     add(TMP, TMP, Operand(size_reg));
     str(TMP, Address(TMP2, size_field_offset));
   }
 }
 
 
+void Assembler::MaybeTraceAllocation(intptr_t cid,
+                                     Register temp_reg,
+                                     Register pp,
+                                     Label* trace) {
+  ASSERT(cid > 0);
+  Isolate* isolate = Isolate::Current();
+  ClassTable* class_table = isolate->class_table();
+  const uword class_offset = cid * sizeof(ClassHeapStats);  // NOLINT
+  if (cid < kNumPredefinedCids) {
+    const uword class_heap_stats_table_address =
+        class_table->PredefinedClassHeapStatsTableAddress();
+    LoadImmediate(temp_reg, class_heap_stats_table_address + class_offset, pp);
+  } else {
+    LoadImmediate(temp_reg, class_table->ClassStatsTableAddress(), pp);
+    ldr(temp_reg, Address(temp_reg, 0));
+    AddImmediate(temp_reg, temp_reg, class_offset, pp);
+  }
+  const uword state_offset = ClassHeapStats::state_offset();
+  const Address& state_address = Address(temp_reg, state_offset);
+  ldr(temp_reg, state_address);
+  tsti(temp_reg, Immediate(ClassHeapStats::TraceAllocationMask()));
+  b(trace, NE);
+}
+
+
 void Assembler::TryAllocate(const Class& cls,
                             Label* failure,
                             Register instance_reg,
                             Register temp_reg,
                             Register pp) {
   ASSERT(failure != NULL);
   if (FLAG_inline_alloc) {
+    // If this allocation is traced, program will jump to failure path
+    // (i.e. the allocation stub) which will allocate the object and trace the
+    // allocation call site.
+    MaybeTraceAllocation(cls.id(), temp_reg, pp, failure);
     const intptr_t instance_size = cls.instance_size();
     Heap* heap = Isolate::Current()->heap();
     Heap::Space space = heap->SpaceForAllocation(cls.id());
     const uword top_address = heap->TopAddress(space);
     LoadImmediate(temp_reg, top_address, pp);
     ldr(instance_reg, Address(temp_reg));
     // TODO(koda): Protect against unsigned overflow here.
     AddImmediateSetFlags(instance_reg, instance_reg, instance_size, pp);
 
     // instance_reg: potential next object start.
@@ skipping 106 matching lines @@
     add(base, array, Operand(index, LSL, shift));
   }
   const OperandSize size = Address::OperandSizeFor(cid);
   ASSERT(Address::CanHoldOffset(offset, Address::Offset, size));
   return Address(base, offset, Address::Offset, size);
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM64