VM: Optimized context allocation on all platforms.

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"
 #if defined(TARGET_ARCH_ARM64)
 
 #include "vm/assembler.h"
 #include "vm/cpu.h"
 #include "vm/longjump.h"
@@ skipping 1395 matching lines @@
     ASSERT(cls.id() != kIllegalCid);
     tags = RawObject::ClassIdTag::update(cls.id(), tags);
     LoadImmediate(TMP, tags, pp);
     StoreFieldToOffset(TMP, instance_reg, Object::tags_offset(), pp);
   } else {
     b(failure);
   }
 }
 
 
+void Assembler::TryAllocateArray(intptr_t cid,
+                                 intptr_t instance_size,
+                                 Label* failure,
+                                 Register instance,
+                                 Register end_address,
+                                 Register temp1,
+                                 Register temp2) {
+  if (FLAG_inline_alloc) {
+    Isolate* isolate = Isolate::Current();
+    Heap* heap = isolate->heap();
+    LoadImmediate(temp1, heap->TopAddress(), PP);
+    ldr(instance, Address(temp1, 0));  // Potential new object start.
+    AddImmediate(end_address, instance, instance_size, PP);
+    b(failure, VS);
+
+    // Check if the allocation fits into the remaining space.
+    // instance: potential new object start.
+    // end_address: potential next object start.
+    LoadImmediate(temp2, heap->EndAddress(), PP);
+    ldr(temp2, Address(temp2, 0));
+    cmp(end_address, Operand(temp2));
+    b(failure, CS);
+
+    // Successfully allocated the object(s), now update top to point to
+    // next object start and initialize the object.
+    str(end_address, Address(temp1, 0));
+    add(instance, instance, Operand(kHeapObjectTag));
+    LoadImmediate(temp2, instance_size, PP);
+    UpdateAllocationStatsWithSize(cid, temp2, PP);
+
+    // Initialize the tags.
+    // instance: new object start as a tagged pointer.
+    uword tags = 0;
+    tags = RawObject::ClassIdTag::update(cid, tags);
+    tags = RawObject::SizeTag::update(instance_size, tags);
+    LoadImmediate(temp2, tags, PP);
+    str(temp2, FieldAddress(instance, Array::tags_offset()));  // Store tags.
+  } else {
+    b(failure);
+  }
+}
+
+
 Address Assembler::ElementAddressForIntIndex(bool is_external,
                                              intptr_t cid,
                                              intptr_t index_scale,
                                              Register array,
                                              intptr_t index) const {
   const int64_t offset = index * index_scale +
       (is_external ? 0 : (Instance::DataOffsetFor(cid) - kHeapObjectTag));
   ASSERT(Utils::IsInt(32, offset));
   const OperandSize size = Address::OperandSizeFor(cid);
   ASSERT(Address::CanHoldOffset(offset, Address::Offset, size));
@@ skipping 23 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