Shorter TryAllocate instruction sequence on ARM/ARM64/MIPS.

runtime/vm/assembler_arm.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_ARM)
 
 #include "vm/assembler.h"
 #include "vm/cpu.h"
 #include "vm/longjump.h"
@@ skipping 3128 matching lines @@
   }
 }
 
 
 void Assembler::TryAllocate(const Class& cls,
                             Label* failure,
                             Register instance_reg,
                             Register temp_reg) {
   ASSERT(failure != NULL);
   if (FLAG_inline_alloc) {
-    Heap* heap = Isolate::Current()->heap();
+    ASSERT(instance_reg != temp_reg);
+    ASSERT(temp_reg != IP);
     const intptr_t instance_size = cls.instance_size();
-    LoadImmediate(instance_reg, heap->TopAddress());
-    ldr(instance_reg, Address(instance_reg, 0));
+
+    LoadImmediate(temp_reg, Isolate::Current()->heap()->NewSpaceAddress());
+
+    ldr(instance_reg, Address(temp_reg, Scavenger::top_offset()));
     AddImmediate(instance_reg, instance_size);
 
     // instance_reg: potential next object start.
-    LoadImmediate(IP, heap->EndAddress());
-    ldr(IP, Address(IP, 0));
+    ldr(IP, Address(temp_reg, Scavenger::end_offset()));
     cmp(IP, Operand(instance_reg));
     // fail if heap end unsigned less than or equal to instance_reg.
     b(failure, LS);
 
     // Successfully allocated the object, now update top to point to
     // next object start and store the class in the class field of object.
-    LoadImmediate(IP, heap->TopAddress());
-    str(instance_reg, Address(IP, 0));
+    str(instance_reg, Address(temp_reg, Scavenger::top_offset()));
 
     ASSERT(instance_size >= kHeapObjectTag);
     AddImmediate(instance_reg, -instance_size + kHeapObjectTag);
     UpdateAllocationStats(cls.id(), temp_reg);
 
     uword tags = 0;
     tags = RawObject::SizeTag::update(instance_size, tags);
     ASSERT(cls.id() != kIllegalCid);
     tags = RawObject::ClassIdTag::update(cls.id(), tags);
     LoadImmediate(IP, tags);
@@ skipping 147 matching lines @@
 
 
 const char* Assembler::FpuRegisterName(FpuRegister reg) {
   ASSERT((0 <= reg) && (reg < kNumberOfFpuRegisters));
   return fpu_reg_names[reg];
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM