Improve Hydrogen code for accessing undefined/null/Infinity.

src/runtime.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 3920 matching lines @@
       // Character array used for conversion.
       static const char kCharTable[] = "0123456789abcdefghijklmnopqrstuvwxyz";
       return isolate->heap()->
           LookupSingleCharacterStringFromCode(kCharTable[value]);
     }
   }
 
   // Slow case.
   CONVERT_DOUBLE_ARG_CHECKED(value, 0);
   if (isnan(value)) {
-    return isolate->heap()->AllocateStringFromAscii(CStrVector("NaN"));
+    return *isolate->factory()->nan_symbol();
   }
   if (isinf(value)) {
     if (value < 0) {
-      return isolate->heap()->AllocateStringFromAscii(CStrVector("-Infinity"));
+      return *isolate->factory()->minus_infinity_symbol();
     }
-    return isolate->heap()->AllocateStringFromAscii(CStrVector("Infinity"));
+    return *isolate->factory()->infinity_symbol();
   }
   char* str = DoubleToRadixCString(value, radix);
   MaybeObject* result =
       isolate->heap()->AllocateStringFromAscii(CStrVector(str));
   DeleteArray(str);
   return result;
 }
 
 
 RUNTIME_FUNCTION(MaybeObject*, Runtime_NumberToFixed) {
   NoHandleAllocation ha;
   ASSERT(args.length() == 2);
 
   CONVERT_DOUBLE_ARG_CHECKED(value, 0);
   if (isnan(value)) {
-    return isolate->heap()->AllocateStringFromAscii(CStrVector("NaN"));
+    return *isolate->factory()->nan_symbol();
   }
   if (isinf(value)) {
     if (value < 0) {
-      return isolate->heap()->AllocateStringFromAscii(CStrVector("-Infinity"));
+      return *isolate->factory()->minus_infinity_symbol();
     }
-    return isolate->heap()->AllocateStringFromAscii(CStrVector("Infinity"));
+    return *isolate->factory()->infinity_symbol();
   }
   CONVERT_DOUBLE_ARG_CHECKED(f_number, 1);
   int f = FastD2I(f_number);
   RUNTIME_ASSERT(f >= 0);
   char* str = DoubleToFixedCString(value, f);
   MaybeObject* res =
       isolate->heap()->AllocateStringFromAscii(CStrVector(str));
   DeleteArray(str);
   return res;
 }
 
 
 RUNTIME_FUNCTION(MaybeObject*, Runtime_NumberToExponential) {
   NoHandleAllocation ha;
   ASSERT(args.length() == 2);
 
   CONVERT_DOUBLE_ARG_CHECKED(value, 0);
   if (isnan(value)) {
-    return isolate->heap()->AllocateStringFromAscii(CStrVector("NaN"));
+    return *isolate->factory()->nan_symbol();
   }
   if (isinf(value)) {
     if (value < 0) {
-      return isolate->heap()->AllocateStringFromAscii(CStrVector("-Infinity"));
+      return *isolate->factory()->minus_infinity_symbol();
     }
-    return isolate->heap()->AllocateStringFromAscii(CStrVector("Infinity"));
+    return *isolate->factory()->infinity_symbol();
   }
   CONVERT_DOUBLE_ARG_CHECKED(f_number, 1);
   int f = FastD2I(f_number);
   RUNTIME_ASSERT(f >= -1 && f <= 20);
   char* str = DoubleToExponentialCString(value, f);
   MaybeObject* res =
       isolate->heap()->AllocateStringFromAscii(CStrVector(str));
   DeleteArray(str);
   return res;
 }
 
 
 RUNTIME_FUNCTION(MaybeObject*, Runtime_NumberToPrecision) {
   NoHandleAllocation ha;
   ASSERT(args.length() == 2);
 
   CONVERT_DOUBLE_ARG_CHECKED(value, 0);
   if (isnan(value)) {
-    return isolate->heap()->AllocateStringFromAscii(CStrVector("NaN"));
+    return *isolate->factory()->nan_symbol();
   }
   if (isinf(value)) {
     if (value < 0) {
-      return isolate->heap()->AllocateStringFromAscii(CStrVector("-Infinity"));
+      return *isolate->factory()->minus_infinity_symbol();
     }
-    return isolate->heap()->AllocateStringFromAscii(CStrVector("Infinity"));
+    return *isolate->factory()->infinity_symbol();
   }
   CONVERT_DOUBLE_ARG_CHECKED(f_number, 1);
   int f = FastD2I(f_number);
   RUNTIME_ASSERT(f >= 1 && f <= 21);
   char* str = DoubleToPrecisionCString(value, f);
   MaybeObject* res =
       isolate->heap()->AllocateStringFromAscii(CStrVector(str));
   DeleteArray(str);
   return res;
 }
@@ skipping 9176 matching lines @@
   } else {
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags);
   }
 }
 
 
 } }  // namespace v8::internal