Allocation space decisions are precisely made in hydrogen.

src/arm/lithium-codegen-arm.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 5335 matching lines @@
 
   Register result = ToRegister(instr->result());
   Register scratch = ToRegister(instr->temp1());
   Register scratch2 = ToRegister(instr->temp2());
 
   // Allocate memory for the object.
   AllocationFlags flags = TAG_OBJECT;
   if (instr->hydrogen()->MustAllocateDoubleAligned()) {
     flags = static_cast<AllocationFlags>(flags | DOUBLE_ALIGNMENT);
   }
-  if (instr->hydrogen()->CanAllocateInOldPointerSpace()) {
-    ASSERT(!instr->hydrogen()->CanAllocateInOldDataSpace());
+  if (instr->hydrogen()->IsOldPointerSpaceAllocation()) {
+    ASSERT(!instr->hydrogen()->IsOldDataSpaceAllocation());
+    ASSERT(!instr->hydrogen()->IsNewSpaceAllocation());
     flags = static_cast<AllocationFlags>(flags | PRETENURE_OLD_POINTER_SPACE);
-  } else if (instr->hydrogen()->CanAllocateInOldDataSpace()) {
+  } else if (instr->hydrogen()->IsOldDataSpaceAllocation()) {
+    ASSERT(!instr->hydrogen()->IsNewSpaceAllocation());
     flags = static_cast<AllocationFlags>(flags | PRETENURE_OLD_DATA_SPACE);
   }
 
   if (instr->size()->IsConstantOperand()) {
     int32_t size = ToInteger32(LConstantOperand::cast(instr->size()));
     __ Allocate(size, result, scratch, scratch2, deferred->entry(), flags);
   } else {
     Register size = ToRegister(instr->size());
     __ Allocate(size,
                 result,
@@ skipping 38 matching lines @@
   if (instr->size()->IsRegister()) {
     Register size = ToRegister(instr->size());
     ASSERT(!size.is(result));
     __ SmiTag(size);
     __ push(size);
   } else {
     int32_t size = ToInteger32(LConstantOperand::cast(instr->size()));
     __ Push(Smi::FromInt(size));
   }
 
-  if (instr->hydrogen()->CanAllocateInOldPointerSpace()) {
-    ASSERT(!instr->hydrogen()->CanAllocateInOldDataSpace());
+  if (instr->hydrogen()->IsOldPointerSpaceAllocation()) {
+    ASSERT(!instr->hydrogen()->IsOldDataSpaceAllocation());
+    ASSERT(!instr->hydrogen()->IsNewSpaceAllocation());
     CallRuntimeFromDeferred(Runtime::kAllocateInOldPointerSpace, 1, instr);
-  } else if (instr->hydrogen()->CanAllocateInOldDataSpace()) {
+  } else if (instr->hydrogen()->IsOldDataSpaceAllocation()) {
+    ASSERT(!instr->hydrogen()->IsNewSpaceAllocation());
     CallRuntimeFromDeferred(Runtime::kAllocateInOldDataSpace, 1, instr);
   } else {
     CallRuntimeFromDeferred(Runtime::kAllocateInNewSpace, 1, instr);
   }
   __ StoreToSafepointRegisterSlot(r0, result);
 }
 
 
 void LCodeGen::DoToFastProperties(LToFastProperties* instr) {
   ASSERT(ToRegister(instr->value()).is(r0));
@@ skipping 404 matching lines @@
   __ sub(scratch, result, Operand::PointerOffsetFromSmiKey(index));
   __ ldr(result, FieldMemOperand(scratch,
                                  FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal