Trace allocation of arrays

runtime/vm/stub_code_x64.cc

 // Copyright (c) 2013, 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"
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/assembler.h"
 #include "vm/compiler.h"
 #include "vm/dart_entry.h"
@@ skipping 593 matching lines @@
 //   RBX : array element type (either NULL or an instantiated type).
 // NOTE: R10 cannot be clobbered here as the caller relies on it being saved.
 // The newly allocated object is returned in RAX.
 void StubCode::GeneratePatchableAllocateArrayStub(Assembler* assembler,
     uword* entry_patch_offset, uword* patch_code_pc_offset) {
   // Must load pool pointer before being able to patch.
   Register new_pp = R13;
   __ LoadPoolPointer(new_pp);
   *entry_patch_offset = assembler->CodeSize();
   Label slow_case;
+  Isolate* isolate = Isolate::Current();
+  const Class& cls = Class::Handle(isolate->object_store()->array_class());
+  ASSERT(!cls.IsNull());
   // Compute the size to be allocated, it is based on the array length
   // and is computed as:
   // RoundedAllocationSize((array_length * kwordSize) + sizeof(RawArray)).
   __ movq(RDI, R10);  // Array Length.
   // Check that length is a positive Smi.
   __ testq(RDI, Immediate(kSmiTagMask));
-  __ j(NOT_ZERO, &slow_case);
+  if (FLAG_use_slow_path || cls.trace_allocation()) {
+    __ jmp(&slow_case);
+  } else {
+    __ j(NOT_ZERO, &slow_case);
+  }
   __ cmpq(RDI, Immediate(0));
   __ j(LESS, &slow_case);
   // Check for maximum allowed length.
   const Immediate& max_len =
       Immediate(reinterpret_cast<int64_t>(Smi::New(Array::kMaxElements)));
   __ cmpq(RDI, max_len);
   __ j(GREATER, &slow_case);
   const intptr_t fixed_size = sizeof(RawArray) + kObjectAlignment - 1;
   __ leaq(RDI, Address(RDI, TIMES_4, fixed_size));  // RDI is a Smi.
   ASSERT(kSmiTagShift == 1);
   __ andq(RDI, Immediate(-kObjectAlignment));
 
-  Isolate* isolate = Isolate::Current();
   Heap* heap = isolate->heap();
   const intptr_t cid = kArrayCid;
   Heap::Space space = heap->SpaceForAllocation(cid);
   __ movq(RAX, Immediate(heap->TopAddress(space)));
   __ movq(RAX, Address(RAX, 0));
 
   // RDI: allocation size.
   __ movq(RCX, RAX);
   __ addq(RCX, RDI);
   __ j(CARRY, &slow_case);
@@ skipping 1533 matching lines @@
 // Result:
 //  RCX: entry point.
 void StubCode::GenerateMegamorphicLookupStub(Assembler* assembler) {
   EmitMegamorphicLookup(assembler, RDI, RBX, RCX);
   __ ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64