MIPS: Inline zero argument array constructor.

src/mips/code-stubs-mips.cc

 // Copyright 2012 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 5987 matching lines @@
     __ Addu(a3, a3, Operand(1));
     __ lw(t1, FieldMemOperand(a2, Cell::kValueOffset));
 
     if (FLAG_debug_code) {
       __ lw(t1, FieldMemOperand(t1, 0));
       __ LoadRoot(at, Heap::kAllocationSiteMapRootIndex);
       __ Assert(eq, kExpectedAllocationSiteInCell, t1, Operand(at));
       __ lw(t1, FieldMemOperand(a2, Cell::kValueOffset));
     }
 
-    // Save the resulting elements kind in type info
-    __ SmiTag(a3);
-    __ lw(t1, FieldMemOperand(a2, Cell::kValueOffset));
-    __ sw(a3, FieldMemOperand(t1, AllocationSite::kTransitionInfoOffset));
-    __ SmiUntag(a3);
+    // Save the resulting elements kind in type info. We can't just store r3

[Paul Lind, 2013/11/14 18:36:15]

comment nit: register a3

+    // in the AllocationSite::transition_info field because elements kind is
+    // restricted to a portion of the field...upper bits need to be left alone.
+    STATIC_ASSERT(AllocationSite::ElementsKindBits::kShift == 0);
+    __ lw(t0, FieldMemOperand(t1, AllocationSite::kTransitionInfoOffset));
+    __ Addu(t0, t0, Operand(Smi::FromInt(kFastElementsKindPackedToHoley)));
+    __ sw(t0, FieldMemOperand(t1, AllocationSite::kTransitionInfoOffset));
+
 
     __ bind(&normal_sequence);
     int last_index = GetSequenceIndexFromFastElementsKind(
         TERMINAL_FAST_ELEMENTS_KIND);
     for (int i = 0; i <= last_index; ++i) {
       Label next;
       ElementsKind kind = GetFastElementsKindFromSequenceIndex(i);
       __ Branch(&next, ne, a3, Operand(kind));
       ArraySingleArgumentConstructorStub stub(kind);
       __ TailCallStub(&stub);
@@ skipping 121 matching lines @@
   __ lw(a3, FieldMemOperand(a2, Cell::kValueOffset));
 
   // If the type cell is undefined, or contains anything other than an
   // AllocationSite, call an array constructor that doesn't use AllocationSites.
   __ lw(t0, FieldMemOperand(a3, 0));
   __ LoadRoot(at, Heap::kAllocationSiteMapRootIndex);
   __ Branch(&no_info, ne, t0, Operand(at));
 
   __ lw(a3, FieldMemOperand(a3, AllocationSite::kTransitionInfoOffset));
   __ SmiUntag(a3);
+  STATIC_ASSERT(AllocationSite::ElementsKindBits::kShift == 0);
+  __ And(a3, a3, Operand(AllocationSite::ElementsKindBits::kMask));
   GenerateDispatchToArrayStub(masm, DONT_OVERRIDE);
 
   __ bind(&no_info);
   GenerateDispatchToArrayStub(masm, DISABLE_ALLOCATION_SITES);
 }
 
 
 void InternalArrayConstructorStub::GenerateCase(
     MacroAssembler* masm, ElementsKind kind) {
   Label not_zero_case, not_one_case;
@@ skipping 75 matching lines @@
   __ bind(&fast_elements_case);
   GenerateCase(masm, FAST_ELEMENTS);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_MIPS