Enable preaging of code objects when --optimize-for-size.

src/arm/macro-assembler-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 898 matching lines @@
   CompareRoot(object, Heap::kUndefinedValueRootIndex);
   b(ne, not_int32);
   // |undefined| is truncated to 0.
   mov(dst, Operand(Smi::FromInt(0)));
   // Fall through.
 
   bind(&done);
 }
 
 
+void MacroAssembler::Prologue(PrologueFrameMode frame_mode) {
+  if (frame_mode == BUILD_STUB_FRAME) {
+    stm(db_w, sp, cp.bit() | fp.bit() | lr.bit());
+    Push(Smi::FromInt(StackFrame::STUB));
+    // Adjust FP to point to saved FP.
+    add(fp, sp, Operand(2 * kPointerSize));
+  } else {
+    PredictableCodeSizeScope predictible_code_size_scope(
+        this, kNoCodeAgeSequenceLength * Assembler::kInstrSize);
+    // The following three instructions must remain together and unmodified
+    // for code aging to work properly.
+    if (FLAG_optimize_for_size && FLAG_age_code) {
+      // Pre-age the code.
+      Code* stub = Code::GetPreAgedCodeAgeStub(isolate());
+      add(r0, pc, Operand(-8));
+      ldr(pc, MemOperand(pc, -4));
+      dd(reinterpret_cast<uint32_t>(stub->instruction_start()));
+    } else {
+      stm(db_w, sp, r1.bit() | cp.bit() | fp.bit() | lr.bit());
+      nop(ip.code());
+      // Adjust FP to point to saved FP.
+      add(fp, sp, Operand(2 * kPointerSize));
+    }
+  }
+}
+
+
 void MacroAssembler::EnterFrame(StackFrame::Type type) {
   // r0-r3: preserved
   stm(db_w, sp, cp.bit() | fp.bit() | lr.bit());
   mov(ip, Operand(Smi::FromInt(type)));
   push(ip);
   mov(ip, Operand(CodeObject()));
   push(ip);
   add(fp, sp, Operand(3 * kPointerSize));  // Adjust FP to point to saved FP.
 }
 
@@ skipping 3036 matching lines @@
 void CodePatcher::EmitCondition(Condition cond) {
   Instr instr = Assembler::instr_at(masm_.pc_);
   instr = (instr & ~kCondMask) | cond;
   masm_.emit(instr);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM