Fix x64 performance regression, array allocation was always going via runtime. Improvements: Havlak…

runtime/vm/intrinsifier_x64.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/globals.h"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/intrinsifier.h"
 
 #include "vm/assembler.h"
@@ skipping 43 matching lines @@
 
   // RDI: allocation size.
   __ movq(RAX, Immediate(heap->TopAddress()));
   __ movq(RAX, Address(RAX, 0));
   __ leaq(RCX, Address(RAX, RDI, TIMES_1, 0));
 
   // Check if the allocation fits into the remaining space.
   // RAX: potential new object start.
   // RCX: potential next object start.
   // RDI: allocation size.
-  __ movq(R13, Immediate(heap->TopAddress()));
+  __ movq(R13, Immediate(heap->EndAddress()));
   __ cmpq(RCX, Address(R13, 0));
   __ j(ABOVE_EQUAL, &fall_through);
 
   // Successfully allocated the object(s), now update top to point to
   // next object start and initialize the object.
+  __ movq(R13, Immediate(heap->TopAddress()));
   __ movq(Address(R13, 0), RCX);
   __ addq(RAX, Immediate(kHeapObjectTag));
 
   // Initialize the tags.
   // RAX: new object start as a tagged pointer.
   // RCX: new object end address.

[siva, 2012/08/06 22:47:17]

RCX is not used in the block below, why does it have to be documented here.

[srdjan, 2012/08/06 23:01:02]

Removed from comment.

   // RDI: allocation size.
   {
     Label size_tag_overflow, done;
-    __ cmpl(RDI, Immediate(RawObject::SizeTag::kMaxSizeTag));
+    __ cmpq(RDI, Immediate(RawObject::SizeTag::kMaxSizeTag));
     __ j(ABOVE, &size_tag_overflow, Assembler::kNearJump);
     __ shlq(RDI, Immediate(RawObject::kSizeTagBit - kObjectAlignmentLog2));
     __ jmp(&done, Assembler::kNearJump);
 
     __ Bind(&size_tag_overflow);
     __ movq(RDI, Immediate(0));
     __ Bind(&done);
 
     // Get the class index and insert it into the tags.
     const Class& cls = Class::Handle(isolate->object_store()->array_class());
     __ orq(RDI, Immediate(RawObject::ClassIdTag::encode(cls.id())));
     __ movq(FieldAddress(RAX, Array::tags_offset()), RDI);  // Tags.
   }
 
   // RAX: new object start as a tagged pointer.
   // RCX: new object end address.

[siva, 2012/08/06 22:47:17]

Ditto comment regarding RCX.

[srdjan, 2012/08/06 23:01:02]

Removed from comment.

   // Store the type argument field.
-  __ movl(RDI, Address(RSP, kTypeArgumentsOffset));  // type argument.
+  __ movq(RDI, Address(RSP, kTypeArgumentsOffset));  // type argument.
   __ StoreIntoObjectNoBarrier(RAX,
                               FieldAddress(RAX, Array::type_arguments_offset()),
                               RDI);
 
   // Set the length field.
   __ movq(RDI, Address(RSP, kArrayLengthOffset));  // Array Length.
   __ StoreIntoObjectNoBarrier(RAX,
                               FieldAddress(RAX, Array::length_offset()),
                               RDI);
 
@@ skipping 1213 matching lines @@
   __ LoadObject(RAX, bool_true);
   __ ret();
   return true;
 }
 
 #undef __
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64