Fast allocation of block contexts.

src/arm/code-stubs-arm.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 171 matching lines @@
   __ mov(cp, r0);
   __ pop();
   __ Ret();
 
   // Need to collect. Call into runtime system.
   __ bind(&gc);
   __ TailCallRuntime(Runtime::kNewFunctionContext, 1, 1);
 }
 
 
+void FastNewBlockContextStub::Generate(MacroAssembler* masm) {
+  // Stack layout on entry:
+  //
+  // [sp]: function.
+  // [sp + kPointerSize]: serialized scope info
+
+  // Try to allocate the context in new space.
+  Label gc;
+  int length = slots_ + Context::MIN_CONTEXT_SLOTS;
+  __ AllocateInNewSpace(FixedArray::SizeFor(length),
+                        r0, r1, r2, &gc, TAG_OBJECT);
+
+  // Load the function from the stack.
+  __ ldr(r3, MemOperand(sp, 0));
+
+  // Load the serialized scope info from the stack.
+  __ ldr(r1, MemOperand(sp, 1 * kPointerSize));
+
+  // Setup the object header.
+  __ LoadRoot(r2, Heap::kBlockContextMapRootIndex);
+  __ str(r2, FieldMemOperand(r0, HeapObject::kMapOffset));
+  __ mov(r2, Operand(Smi::FromInt(length)));
+  __ str(r2, FieldMemOperand(r0, FixedArray::kLengthOffset));
+
+  // If this block context is nested in the global context we get a smi
+  // sentinel instead of a function. The block context should get the
+  // canonical empty function of the global context as its closure which
+  // we still have to look up.
+  Label after_sentinel;
+  __ JumpIfNotSmi(r3, &after_sentinel);

[danno, 2011/10/06 14:44:08]

Make a debug check for zero? 

[Steven, 2011/10/06 16:02:40]

Done.

+  __ ldr(r3, GlobalObjectOperand());
+  __ ldr(r3, FieldMemOperand(r3, GlobalObject::kGlobalContextOffset));
+  __ ldr(r3, ContextOperand(r3, Context::CLOSURE_INDEX));
+  __ bind(&after_sentinel);
+
+  // Setup the fixed slots.
+  __ str(r3, ContextOperand(r0, Context::CLOSURE_INDEX));
+  __ str(cp, ContextOperand(r0, Context::PREVIOUS_INDEX));
+  __ str(r1, ContextOperand(r0, Context::EXTENSION_INDEX));
+
+  // Copy the global object from the previous context.
+  __ ldr(r1, ContextOperand(cp, Context::GLOBAL_INDEX));
+  __ str(r1, ContextOperand(r0, Context::GLOBAL_INDEX));
+
+  // Initialize the rest of the slots to the hole value.
+  __ LoadRoot(r1, Heap::kTheHoleValueRootIndex);
+  for (int i = 0; i < slots_; i++) {
+    __ str(r1, ContextOperand(r0, i + Context::MIN_CONTEXT_SLOTS));
+  }
+
+  // Remove the on-stack argument and return.
+  __ mov(cp, r0);
+  __ add(sp, sp, Operand(2 * kPointerSize));
+  __ Ret();
+
+  // Need to collect. Call into runtime system.
+  __ bind(&gc);
+  __ TailCallRuntime(Runtime::kPushBlockContext, 2, 1);
+}
+
+
 void FastCloneShallowArrayStub::Generate(MacroAssembler* masm) {
   // Stack layout on entry:
   //
   // [sp]: constant elements.
   // [sp + kPointerSize]: literal index.
   // [sp + (2 * kPointerSize)]: literals array.
 
   // All sizes here are multiples of kPointerSize.
   int elements_size = (length_ > 0) ? FixedArray::SizeFor(length_) : 0;
   int size = JSArray::kSize + elements_size;
@@ skipping 6884 matching lines @@
 
   // Fall through when we need to inform the incremental marker.
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM