Unroll more StringDictionary lookup probes both for positive and negative dictionary lookups.

src/ia32/ic-ia32.cc

 // Copyright 2011 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 122 matching lines @@
     if (i > 0) {
       __ add(Operand(r0), Immediate(StringDictionary::GetProbeOffset(i)));
     }
     __ and_(r0, Operand(r1));
 
     // Scale the index by multiplying by the entry size.
     ASSERT(StringDictionary::kEntrySize == 3);
     __ lea(r0, Operand(r0, r0, times_2, 0));  // r0 = r0 * 3
 
     // Check if the key is identical to the name.
-    __ cmp(name, Operand(elements, r0, times_4,
+    __ cmp(name, Operand(elements,
+                         r0,
+                         times_4,
                          kElementsStartOffset - kHeapObjectTag));
-    if (i != kProbes - 1) {
-      __ j(equal, done, taken);
-    } else {
-      __ j(not_equal, miss, not_taken);
-    }
+    __ j(equal, done, taken);
   }
+
+  StringDictionaryLookupStub stub(elements,
+                                  r1,
+                                  r0,
+                                  StringDictionaryLookupStub::POSITIVE_LOOKUP);
+  __ push(name);
+  __ mov(r0, FieldOperand(name, String::kHashFieldOffset));
+  __ shr(r0, String::kHashShift);
+  __ push(r0);
+  __ CallStub(&stub);
+
+  __ test(r1, Operand(r1));
+  __ j(zero, miss);
+  __ jmp(done);
 }
 
 
 
 // Helper function used to load a property from a dictionary backing
 // storage. This function may fail to load a property even though it is
 // in the dictionary, so code at miss_label must always call a backup
 // property load that is complete. This function is safe to call if
 // name is not a symbol, and will jump to the miss_label in that
 // case. The generated code assumes that the receiver has slow
@@ skipping 1431 matching lines @@
   Condition cc = *jmp_address == Assembler::kJncShortOpcode
       ? not_zero
       : zero;
   *jmp_address = static_cast<byte>(Assembler::kJccShortPrefix | cc);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32