Pretenure ASCII cons string in high promotion mode.

src/ia32/code-stubs-ia32.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 5820 matching lines @@
   __ j(zero, &non_ascii);
   __ bind(&ascii_data);
   // Allocate an ASCII cons string.
   __ AllocateAsciiConsString(ecx, edi, no_reg, &call_runtime);
   __ bind(&allocated);
   // Fill the fields of the cons string.
   __ AssertSmi(ebx);
   __ mov(FieldOperand(ecx, ConsString::kLengthOffset), ebx);
   __ mov(FieldOperand(ecx, ConsString::kHashFieldOffset),
          Immediate(String::kEmptyHashField));
+
+  Label skip_write_barrier, after_writing;
+  ExternalReference high_promotion_mode = ExternalReference::
+      new_space_high_promotion_mode_active_address(masm->isolate());
+  __ test(Operand::StaticVariable(high_promotion_mode), Immediate(1));
+  __ j(zero, &skip_write_barrier);
+
+  __ mov(FieldOperand(ecx, ConsString::kFirstOffset), eax);
+  __ RecordWriteField(ecx,
+                     ConsString::kFirstOffset,
+                     eax,
+                     ebx,
+                     kDontSaveFPRegs);
+  __ mov(FieldOperand(ecx, ConsString::kSecondOffset), edx);
+  __ RecordWriteField(ecx,
+                     ConsString::kSecondOffset,
+                     edx,
+                     ebx,
+                     kDontSaveFPRegs);
+  __ jmp(&after_writing);
+
+  __ bind(&skip_write_barrier);
   __ mov(FieldOperand(ecx, ConsString::kFirstOffset), eax);
   __ mov(FieldOperand(ecx, ConsString::kSecondOffset), edx);
+
+  __ bind(&after_writing);
+
   __ mov(eax, ecx);
   __ IncrementCounter(counters->string_add_native(), 1);
   __ ret(2 * kPointerSize);
   __ bind(&non_ascii);
   // At least one of the strings is two-byte. Check whether it happens
   // to contain only one byte characters.
   // ecx: first instance type AND second instance type.
   // edi: second instance type.
   __ test(ecx, Immediate(kOneByteDataHintMask));
   __ j(not_zero, &ascii_data);
@@ skipping 1511 matching lines @@
   // ElementsTransitionGenerator::GenerateMapChangeElementTransition
   // and ElementsTransitionGenerator::GenerateSmiToDouble
   // and ElementsTransitionGenerator::GenerateDoubleToObject
   { REG(edx), REG(ebx), REG(edi), EMIT_REMEMBERED_SET},
   { REG(edx), REG(ebx), REG(edi), OMIT_REMEMBERED_SET},
   // ElementsTransitionGenerator::GenerateDoubleToObject
   { REG(eax), REG(edx), REG(esi), EMIT_REMEMBERED_SET},
   { REG(edx), REG(eax), REG(edi), EMIT_REMEMBERED_SET},
   // StoreArrayLiteralElementStub::Generate
   { REG(ebx), REG(eax), REG(ecx), EMIT_REMEMBERED_SET},
-  // FastNewClosureStub
+  // FastNewClosureStub and StringAddStub::Generate
   { REG(ecx), REG(edx), REG(ebx), EMIT_REMEMBERED_SET},
+  // StringAddStub::Generate
+  { REG(ecx), REG(eax), REG(ebx), EMIT_REMEMBERED_SET},
   // Null termination.
   { REG(no_reg), REG(no_reg), REG(no_reg), EMIT_REMEMBERED_SET}
 };
 
 #undef REG
 
 bool RecordWriteStub::IsPregenerated() {
   for (const AheadOfTimeWriteBarrierStubList* entry = kAheadOfTime;
        !entry->object.is(no_reg);
        entry++) {
@@ skipping 557 matching lines @@
     __ jmp(generic_construct_stub, RelocInfo::CODE_TARGET);
   }
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32