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

src/mips/lithium-codegen-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 121 matching lines @@
   }
 
   info()->set_prologue_offset(masm_->pc_offset());
   if (NeedsEagerFrame()) {
     if (info()->IsStub()) {
       __ Push(ra, fp, cp);
       __ Push(Smi::FromInt(StackFrame::STUB));
       // Adjust FP to point to saved FP.
       __ Addu(fp, sp, Operand(2 * kPointerSize));
     } else {
+      PredictableCodeSizeScope predictible_code_size_scope(
+        masm_, kNoCodeAgeSequenceLength * Assembler::kInstrSize);
       // The following three instructions must remain together and unmodified
       // for code aging to work properly.
-      __ Push(ra, fp, cp, a1);
-      // Add unused nop to ensure prologue sequence is identical for
-      // full-codegen and lithium-codegen.
-      __ nop(Assembler::CODE_AGE_SEQUENCE_NOP);
-      // Adj. FP to point to saved FP.
-      __ Addu(fp, sp, Operand(2 * kPointerSize));
+      if (FLAG_optimize_for_size && FLAG_age_code) {
+        // Pre-age the code.
+        Code* stub = Code::GetPreAgedCodeAgeStub(isolate());
+        __ nop(Assembler::CODE_AGE_MARKER_NOP);
+        // Save the function's original return address
+        // (it will be clobbered by Call(t9))
+        __ mov(at, ra);
+        // Load the stub address to t9 and call it
+        __ li(t9,
+              Operand(reinterpret_cast<uint32_t>(stub->instruction_start())));
+        __ Call(t9);
+        // Record the stub address in the empty space for GetCodeAgeAndParity()
+        __ dd(reinterpret_cast<uint32_t>(stub->instruction_start()));
+      } else {
+        __ Push(ra, fp, cp, a1);
+        __ nop(Assembler::CODE_AGE_SEQUENCE_NOP);
+        // Adjust fp to point to caller's fp.
+        __ Addu(fp, sp, Operand(2 * kPointerSize));
+      }
     }
     frame_is_built_ = true;
     info_->AddNoFrameRange(0, masm_->pc_offset());
   }
 
   // Reserve space for the stack slots needed by the code.
   int slots = GetStackSlotCount();
   if (slots > 0) {
     if (FLAG_debug_code) {
       __ Subu(sp,  sp, Operand(slots * kPointerSize));
@@ skipping 5665 matching lines @@
   __ Subu(scratch, result, scratch);
   __ lw(result, FieldMemOperand(scratch,
                                 FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal