Simplify and fix code aging.

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 118 matching lines @@
   // cp: Callee's context.
   // fp: Caller's frame pointer.
   // lr: Caller's pc.
 
   // Strict mode functions and builtins need to replace the receiver
   // with undefined when called as functions (without an explicit
   // receiver object). r5 is zero for method calls and non-zero for
   // function calls.
   if (!info_->is_classic_mode() || info_->is_native()) {
     Label ok;
-    Label begin;
-    __ bind(&begin);
     __ Branch(&ok, eq, t1, Operand(zero_reg));
 
     int receiver_offset = scope()->num_parameters() * kPointerSize;
     __ LoadRoot(a2, Heap::kUndefinedValueRootIndex);
     __ sw(a2, MemOperand(sp, receiver_offset));
     __ bind(&ok);
-    ASSERT_EQ(kSizeOfOptimizedStrictModePrologue, ok.pos() - begin.pos());
   }
 
+  info()->set_prologue_offset(masm_->pc_offset());
   // The following three instructions must remain together and unmodified for
   // code aging to work properly.
   __ Push(ra, fp, cp, a1);
   // Add unused load of ip to ensure prologue sequence is identical for
   // full-codegen and lithium-codegen.
   __ LoadRoot(at, Heap::kUndefinedValueRootIndex);
   __ Addu(fp, sp, Operand(2 * kPointerSize));  // Adj. FP to point to saved FP.
 
   // Reserve space for the stack slots needed by the code.
   int slots = GetStackSlotCount();
@@ skipping 5341 matching lines @@
   __ Subu(scratch, result, scratch);
   __ lw(result, FieldMemOperand(scratch,
                                 FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal