Avoid calling ToRegister(register) when result is in register already, and re...

src/ia32/virtual-frame-ia32.cc

 // Copyright 2009 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 1022 matching lines @@
 
 Result VirtualFrame::CallKeyedStoreIC() {
   // Value, key, and receiver are on the top of the frame.  The IC
   // expects value in eax, key in ecx, and receiver in edx.
   Result value = Pop();
   Result key = Pop();
   Result receiver = Pop();
   PrepareForCall(0, 0);
   if (!cgen()->allocator()->is_used(eax) ||
       (value.is_register() && value.reg().is(eax))) {
-    value.ToRegister(eax);  // No effect if value is in eax already.
+    if (!cgen()->allocator()->is_used(eax)) {
+      value.ToRegister(eax);
+    }
     MoveResultsToRegisters(&key, &receiver, ecx, edx);
     value.Unuse();
   } else if (!cgen()->allocator()->is_used(ecx) ||
              (key.is_register() && key.reg().is(ecx))) {
-    // Receiver and/or key are in eax.
-    key.ToRegister(ecx);
+    if (!cgen()->allocator()->is_used(ecx)) {
+      key.ToRegister(ecx);
+    }
     MoveResultsToRegisters(&value, &receiver, eax, edx);
     key.Unuse();
   } else if (!cgen()->allocator()->is_used(edx) ||
              (receiver.is_register() && receiver.reg().is(edx))) {
-    receiver.ToRegister(edx);
+    if (!cgen()->allocator()->is_used(edx)) {
+      receiver.ToRegister(edx);
+    }
     MoveResultsToRegisters(&key, &value, ecx, eax);
     receiver.Unuse();
   } else {
     // All three registers are used, and no value is in the correct place.
     // We have one of the two circular permutations of eax, ecx, edx.
     ASSERT(value.is_register());
     if (value.reg().is(ecx)) {
       __ xchg(eax, edx);
       __ xchg(eax, ecx);
     } else {
@@ skipping 214 matching lines @@
       return;
     }
   }
   UNREACHABLE();
 }
 
 
 #undef __
 
 } }  // namespace v8::internal