Zero-sized new-space for VM isolate.

runtime/vm/heap.cc

 // Copyright (c) 2012, 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/heap.h"
 
 #include "platform/assert.h"
 #include "platform/utils.h"
 #include "vm/flags.h"
 #include "vm/isolate.h"
@@ skipping 11 matching lines @@
 
 namespace dart {
 
 DEFINE_FLAG(bool, verbose_gc, false, "Enables verbose GC.");
 DEFINE_FLAG(int, verbose_gc_hdr, 40, "Print verbose GC header interval.");
 DEFINE_FLAG(bool, verify_before_gc, false,
             "Enables heap verification before GC.");
 DEFINE_FLAG(bool, verify_after_gc, false,
             "Enables heap verification after GC.");
 DEFINE_FLAG(bool, gc_at_alloc, false, "GC at every allocation.");
-DEFINE_FLAG(int, new_gen_heap_size, 32, "new gen heap size in MB,"
-            "e.g: --new_gen_heap_size=64 allocates a 64MB new gen heap");
-DEFINE_FLAG(int, old_gen_heap_size, Heap::kHeapSizeInMB,
-            "old gen heap size in MB,"
-            "e.g: --old_gen_heap_size=1024 allocates a 1024MB old gen heap");
 DEFINE_FLAG(int, new_gen_ext_limit, 64,
             "maximum total external size (MB) in new gen before triggering GC");
 
-Heap::Heap() : read_only_(false), gc_in_progress_(false) {
+Heap::Heap(intptr_t max_new_gen_words,

[Ivan Posva, 2014/04/24 17:12:44]

Thanks! This is also a good step towards being able to set different heap sizes
as we span isolates.

+           intptr_t max_old_gen_words)
+    : read_only_(false), gc_in_progress_(false) {
   for (int sel = 0;
        sel < kNumWeakSelectors;
        sel++) {
     new_weak_tables_[sel] = new WeakTable();
     old_weak_tables_[sel] = new WeakTable();
   }
   new_space_ = new Scavenger(this,
-                             (FLAG_new_gen_heap_size * MBInWords),
+                             max_new_gen_words,
                              kNewObjectAlignmentOffset);
-  old_space_ = new PageSpace(this, (FLAG_old_gen_heap_size * MBInWords));
+  old_space_ = new PageSpace(this, max_old_gen_words);
   stats_.num_ = 0;
 }
 
 
 Heap::~Heap() {
   delete new_space_;
   delete old_space_;
   for (int sel = 0;
        sel < kNumWeakSelectors;
        sel++) {
@@ skipping 249 matching lines @@
 uword Heap::TopAddress() {
   return reinterpret_cast<uword>(new_space_->TopAddress());
 }
 
 
 uword Heap::EndAddress() {
   return reinterpret_cast<uword>(new_space_->EndAddress());
 }
 
 
-void Heap::Init(Isolate* isolate) {
+void Heap::Init(Isolate* isolate,
+                intptr_t max_new_gen_words,
+                intptr_t max_old_gen_words) {
   ASSERT(isolate->heap() == NULL);
-  Heap* heap = new Heap();
+  Heap* heap = new Heap(max_new_gen_words, max_old_gen_words);
   isolate->set_heap(heap);
 }
 
 
-void Heap::StartEndAddress(uword* start, uword* end) const {
-  ASSERT(new_space_->CapacityInWords() != 0);
-  new_space_->StartEndAddress(start, end);
+void Heap::GetMergedAddressRange(uword* start, uword* end) const {
+  if (new_space_->CapacityInWords() != 0) {
+    uword new_start;
+    uword new_end;
+    new_space_->StartEndAddress(&new_start, &new_end);
+    *start = Utils::Minimum(new_start, *start);
+    *end = Utils::Maximum(new_end, *end);
+  }
   if (old_space_->CapacityInWords() != 0) {
     uword old_start;
     uword old_end;
     old_space_->StartEndAddress(&old_start, &old_end);
     *start = Utils::Minimum(old_start, *start);
     *end = Utils::Maximum(old_end, *end);
   }
   ASSERT(*start <= *end);
 }
 
 
 ObjectSet* Heap::CreateAllocatedObjectSet() const {
+  uword start = static_cast<uword>(-1);
+  uword end = 0;
+  Isolate* vm_isolate = Dart::vm_isolate();
+  vm_isolate->heap()->GetMergedAddressRange(&start, &end);
   Isolate* isolate = Isolate::Current();
-  uword start, end;
-  isolate->heap()->StartEndAddress(&start, &end);
+  isolate->heap()->GetMergedAddressRange(&start, &end);

[koda, 2014/04/24 00:24:48]

Actually, why do we get explicitly get Isolate::Current()->heap() here, rather
than simply use 'this' (also below)?

[Ivan Posva, 2014/04/24 17:12:44]

Please use this.

[koda, 2014/04/24 17:52:54]

Actually, there was a reason. We need the isolate and a non-const heap pointer
to call the visitor.

I added an ASSERT (also in Verify below) that 'this' is indeed the current heap
and a TODO to beautify this code.

 
-  Isolate* vm_isolate = Dart::vm_isolate();
-  uword vm_start, vm_end;
-  vm_isolate->heap()->StartEndAddress(&vm_start, &vm_end);
-
-  ObjectSet* allocated_set = new ObjectSet(Utils::Minimum(start, vm_start),
-                                           Utils::Maximum(end, vm_end));
+  ObjectSet* allocated_set = new ObjectSet(start, end);
 
   VerifyObjectVisitor object_visitor(isolate, allocated_set);
   isolate->heap()->IterateObjects(&object_visitor);
   vm_isolate->heap()->IterateObjects(&object_visitor);
 
   return allocated_set;
 }
 
 
 bool Heap::Verify() const {
@@ skipping 219 matching lines @@
     heap->DisableGrowthControl();
 }
 
 
 NoHeapGrowthControlScope::~NoHeapGrowthControlScope() {
     Heap* heap = reinterpret_cast<Isolate*>(isolate())->heap();
     heap->SetGrowthControlState(current_growth_controller_state_);
 }
 
 }  // namespace dart