Minor optimization of strtod

include/rapidjson/internal/diyfp.h

@@ -102,8 +102,8 @@ struct DiyFp {
         unsigned long index;
         _BitScanReverse64(&index, f);
         return DiyFp(f << (63 - index), e - (63 - index));
-#elif 0//defined(__GNUC__)
-        int s = __builtin_clzll(f) + 1;
+#elif defined(__GNUC__) && __GNUC__ >= 4
+        int s = __builtin_clzll(f);
         return DiyFp(f << s, e - s);
 #else
         DiyFp res = *this;
@@ -111,22 +111,11 @@ struct DiyFp {
             res.f <<= 1;
             res.e--;
         }
-        // while (!(res.f & kDpHiddenBit)) {
-        //     res.f <<= 1;
-        //     res.e--;
-        // }
-        // res.f <<= (kDiySignificandSize - kDpSignificandSize - 1);
-        // res.e = res.e - (kDiySignificandSize - kDpSignificandSize - 1);
         return res;
 #endif
     }
 
     DiyFp NormalizeBoundary() const {
-#if defined(_MSC_VER) && defined(_M_AMD64)
-        unsigned long index;
-        _BitScanReverse64(&index, f);
-        return DiyFp (f << (63 - index), e - (63 - index));
-#else
         DiyFp res = *this;
         while (!(res.f & (kDpHiddenBit << 1))) {
             res.f <<= 1;
@@ -135,7 +124,6 @@ struct DiyFp {
         res.f <<= (kDiySignificandSize - kDpSignificandSize - 2);
         res.e = res.e - (kDiySignificandSize - kDpSignificandSize - 2);
         return res;
-#endif
     }
 
     void NormalizedBoundaries(DiyFp* minus, DiyFp* plus) const {

include/rapidjson/internal/strtod.h

@@ -179,7 +179,8 @@ inline bool StrtodDiyFp(const char* decimals, size_t length, size_t decimalPosit
             DiyFp(RAPIDJSON_UINT64_C2(0xf4240000, 00000000), -44),  // 10^6
             DiyFp(RAPIDJSON_UINT64_C2(0x98968000, 00000000), -40)   // 10^7
         };
-        int adjustment = dExp - actualExp - 1;        
+        int adjustment = dExp - actualExp - 1;
+        RAPIDJSON_ASSERT(adjustment >= 0 && adjustment < 7);
         v = v * kPow10[adjustment];
         if (length + adjustment > 19) // has more digits than decimal digits in 64-bit
             error += kUlp / 2;