Introduce x87 port

src/strtod.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <stdarg.h>
 #include <cmath>
 
 #include "globals.h"
 #include "utils.h"
 #include "strtod.h"
@@ skipping 135 matching lines @@
     int exponent = 0;
     *result = DiyFp(significand, exponent);
     *remaining_decimals = buffer.length() - read_digits;
   }
 }
 
 
 static bool DoubleStrtod(Vector<const char> trimmed,
                          int exponent,
                          double* result) {
-#if (V8_TARGET_ARCH_IA32 || defined(USE_SIMULATOR)) && !defined(_MSC_VER)
+#if (V8_TARGET_ARCH_IA32 || V8_TARGET_ARCH_X87 || defined(USE_SIMULATOR)) && \
+    !defined(_MSC_VER)
   // On x86 the floating-point stack can be 64 or 80 bits wide. If it is
   // 80 bits wide (as is the case on Linux) then double-rounding occurs and the
   // result is not accurate.
   // We know that Windows32 with MSVC, unlike with MinGW32, uses 64 bits and is
   // therefore accurate.
   // Note that the ARM and MIPS simulators are compiled for 32bits. They
   // therefore exhibit the same problem.
   return false;
 #endif
   if (trimmed.length() <= kMaxExactDoubleIntegerDecimalDigits) {
@@ skipping 243 matching lines @@
 
   double guess;
   if (DoubleStrtod(trimmed, exponent, &guess) ||
       DiyFpStrtod(trimmed, exponent, &guess)) {
     return guess;
   }
   return BignumStrtod(trimmed, exponent, guess);
 }
 
 } }  // namespace v8::internal