Fast algorithm for double->string conversion.

src/checks.h

 // Copyright 2006-2008 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 62 matching lines @@
 static inline void CheckEqualsHelper(const char* file, int line,
                                      const char* expected_source, int expected,
                                      const char* value_source, int value) {
   if (expected != value) {
     V8_Fatal(file, line,
              "CHECK_EQ(%s, %s) failed\n#   Expected: %i\n#   Found: %i",
              expected_source, value_source, expected, value);
   }
 }
 
+
 // Helper function used by the CHECK_EQ function when given int64_t
 // arguments.  Should not be called directly.
 static inline void CheckEqualsHelper(const char* file, int line,
                                      const char* expected_source,
                                      int64_t expected,
                                      const char* value_source,
                                      int64_t value) {
   if (expected != value) {
     // Print int64_t values in hex, as two int32s,
     // to avoid platform-dependencies.
@@ skipping 102 matching lines @@
   if (*exp != *val) {
     V8_Fatal(file, line,
              "CHECK_EQ(%s, %s) failed\n#   Expected: %f\n#   Found: %f",
              expected_source, value_source, *exp, *val);
   }
   delete[] exp;
   delete[] val;
 }
 
 
+static inline void CheckNonEqualsHelper(const char* file,
+                                     int line,
+                                     const char* expected_source,
+                                     double expected,
+                                     const char* value_source,
+                                     double value) {
+  // Force values to 64 bit memory to truncate 80 bit precision on IA32.
+  volatile double* exp = new double[1];
+  *exp = expected;
+  volatile double* val = new double[1];
+  *val = value;
+  if (*exp == *val) {
+    V8_Fatal(file, line,
+             "CHECK_NE(%s, %s) failed\n#   Value: %f",
+             expected_source, value_source, *val);
+  }
+  delete[] exp;
+  delete[] val;
+}
+
+
 namespace v8 {
   class Value;
   template <class T> class Handle;
 }
 
 
 void CheckNonEqualsHelper(const char* file,
                           int line,
                           const char* unexpected_source,
                           v8::Handle<v8::Value> unexpected,
@@ skipping 62 matching lines @@
 
 
 #define ASSERT_TAG_ALIGNED(address) \
   ASSERT((reinterpret_cast<intptr_t>(address) & kHeapObjectTagMask) == 0)
 
 #define ASSERT_SIZE_TAG_ALIGNED(size) ASSERT((size & kHeapObjectTagMask) == 0)
 
 #define ASSERT_NOT_NULL(p)  ASSERT_NE(NULL, p)
 
 #endif  // V8_CHECKS_H_