Track live instance and allocation counts for classes

runtime/vm/stub_code_ia32.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_IA32)
 
 #include "vm/assembler.h"
 #include "vm/compiler.h"
 #include "vm/dart_entry.h"
@@ skipping 570 matching lines @@
     __ j(ABOVE_EQUAL, &slow_case);
 
     // Successfully allocated the object(s), now update top to point to
     // next object start and initialize the object.
     // EAX: potential new object start.
     // EBX: potential next object start.
     // EDX: Array length as Smi.
     // EDI: Points to new space object.
     __ movl(Address(EDI, Scavenger::top_offset()), EBX);
     __ addl(EAX, Immediate(kHeapObjectTag));
+    // EDI: Size of allocation in bytes.

[Ivan Posva, 2013/12/12 13:53:24]

At this point EDI does not contain the size of the allocation in bytes. The
comments are supposed to explain what is in the registers at that particular
point. It is also supposed to convey "register allocation" high-lighting which
registers hold values which will be needed later.

So in this case the comment should be:
// EAX: new object start as tagged pointer
// EBX: next object start (new top)
// ECX: array element type
// EDX: array lenght as Smi

This shows that the length in bytes calculation is broken in this case. It needs
to be moved before the tagging of the new object.

+    __ movl(EDI, EBX);
+    __ subl(EDI, EAX);
+    __ BumpAllocationCount(Heap::kNew, kArrayCid, EDI, kNoRegister);
 
     // EAX: new object start as a tagged pointer.
     // EBX: new object end address.
     // ECX: array element type.
     // EDX: Array length as Smi.
 
     // Store the type argument field.
     __ StoreIntoObjectNoBarrier(
         EAX,
         FieldAddress(EAX, Array::type_arguments_offset()),
@@ skipping 322 matching lines @@
       __ j(ABOVE_EQUAL, &slow_case, Assembler::kNearJump);
     }
 
     // Successfully allocated the object, now update top to point to
     // next object start and initialize the object.
     // EAX: new object.
     // EBX: next object start.
     // EDX: number of context variables.
     __ movl(Address::Absolute(heap->TopAddress()), EBX);
     __ addl(EAX, Immediate(kHeapObjectTag));
+    // EBX: Size of allocation in bytes.

[Ivan Posva, 2013/12/12 13:53:24]

ditto

+    __ subl(EBX, EAX);
+    __ BumpAllocationCount(Heap::kNew, context_class.id(), EBX, kNoRegister);
 
     // Calculate the size tag.
     // EAX: new object.
     // EDX: number of context variables.
     {
       Label size_tag_overflow, done;
       __ leal(EBX, Address(EDX, TIMES_4, fixed_size));
       __ andl(EBX, Immediate(-kObjectAlignment));
       __ cmpl(EBX, Immediate(RawObject::SizeTag::kMaxSizeTag));
       __ j(ABOVE, &size_tag_overflow, Assembler::kNearJump);
@@ skipping 181 matching lines @@
       // ECX: potential new object end and, if ECX != EBX, potential new
       // InstantiatedTypeArguments object start.
     }
     // Check if the allocation fits into the remaining space.
     // EAX: potential new object start.
     // EBX: potential next object start.
     __ cmpl(EBX, Address::Absolute(heap->EndAddress()));
     if (FLAG_use_slow_path) {
       __ jmp(&slow_case);
     } else {
-      __ j(ABOVE_EQUAL, &slow_case, Assembler::kNearJump);
+      __ j(ABOVE_EQUAL, &slow_case);
     }
 
     // Successfully allocated the object(s), now update top to point to
     // next object start and initialize the object.
     __ movl(Address::Absolute(heap->TopAddress()), EBX);
+    __ BumpAllocationCount(Heap::kNew, cls.id(), EDI);
 
     if (is_cls_parameterized) {
       // Initialize the type arguments field in the object.
       // EAX: new object start.
       // ECX: potential new object end and, if ECX != EBX, potential new
       // InstantiatedTypeArguments object start.
       // EBX: next object start.
       Label type_arguments_ready;
       __ movl(EDI, Address(ESP, kObjectTypeArgumentsOffset));
       __ cmpl(ECX, EBX);
@@ skipping 144 matching lines @@
     __ cmpl(EBX, Address::Absolute(heap->EndAddress()));
     if (FLAG_use_slow_path) {
       __ jmp(&slow_case);
     } else {
       __ j(ABOVE_EQUAL, &slow_case, Assembler::kNearJump);
     }
 
     // Successfully allocated the object, now update top to point to
     // next object start and initialize the object.
     __ movl(Address::Absolute(heap->TopAddress()), EBX);
+    // EBX: Size of allocation in bytes.
+    __ subl(EBX, EAX);
+    // EDX: Clobbered.

[Ivan Posva, 2013/12/12 13:53:24]

This should not be necessary if the list of live registers is correct in the
comments.

+    __ BumpAllocationCount(Heap::kNew, cls.id(), EBX, EDX);
 
     // EAX: new closure object.
     // ECX: new context object (only if is_implicit_closure).
     // Set the tags.
     uword tags = 0;
     tags = RawObject::SizeTag::update(closure_size, tags);
     tags = RawObject::ClassIdTag::update(cls.id(), tags);
     __ movl(Address(EAX, Instance::tags_offset()), Immediate(tags));
 
     // Initialize the function field in the object.
     // EAX: new closure object.
     // ECX: new context object (only if is_implicit_closure).
-    // EBX: next object start.
     __ LoadObject(EDX, func);  // Load function of closure to be allocated.
     __ movl(Address(EAX, Closure::function_offset()), EDX);
 
     // Setup the context for this closure.
     if (is_implicit_instance_closure) {
       // Initialize the new context capturing the receiver.
       const Class& context_class = Class::ZoneHandle(Object::context_class());
       // Set the tags.
       uword tags = 0;
       tags = RawObject::SizeTag::update(context_size, tags);
@@ skipping 873 matching lines @@
   const Register temp = ECX;
   __ movl(left, Address(ESP, 2 * kWordSize));
   __ movl(right, Address(ESP, 1 * kWordSize));
   GenerateIdenticalWithNumberCheckStub(assembler, left, right, temp);
   __ ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_IA32