// Copyright 2011 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. #ifndef V8_CONVERSIONS_INL_H_ #define V8_CONVERSIONS_INL_H_ #include <float.h> // Required for DBL_MAX and on Win32 for finite() #include <limits.h> // Required for INT_MAX etc. #include <stdarg.h> #include <cmath> #include "src/globals.h" // Required for V8_INFINITY #include "src/unicode-cache-inl.h" // ---------------------------------------------------------------------------- // Extra POSIX/ANSI functions for Win32/MSVC. #include "src/base/bits.h" #include "src/base/platform/platform.h" #include "src/conversions.h" #include "src/double.h" #include "src/objects-inl.h" #include "src/strtod.h" namespace v8 { namespace internal { inline double JunkStringValue() { return bit_cast<double, uint64_t>(kQuietNaNMask); } inline double SignedZero(bool negative) { return negative ? uint64_to_double(Double::kSignMask) : 0.0; } // The fast double-to-unsigned-int conversion routine does not guarantee // rounding towards zero, or any reasonable value if the argument is larger // than what fits in an unsigned 32-bit integer. inline unsigned int FastD2UI(double x) { // There is no unsigned version of lrint, so there is no fast path // in this function as there is in FastD2I. Using lrint doesn't work // for values of 2^31 and above. // Convert "small enough" doubles to uint32_t by fixing the 32 // least significant non-fractional bits in the low 32 bits of the // double, and reading them from there. const double k2Pow52 = 4503599627370496.0; bool negative = x < 0; if (negative) { x = -x; } if (x < k2Pow52) { x += k2Pow52; uint32_t result; #ifndef V8_TARGET_BIG_ENDIAN Address mantissa_ptr = reinterpret_cast<Address>(&x); #else Address mantissa_ptr = reinterpret_cast<Address>(&x) + kInt32Size; #endif // Copy least significant 32 bits of mantissa. memcpy(&result, mantissa_ptr, sizeof(result)); return negative ? ~result + 1 : result; } // Large number (outside uint32 range), Infinity or NaN. return 0x80000000u; // Return integer indefinite. } inline float DoubleToFloat32(double x) { // TODO(yangguo): This static_cast is implementation-defined behaviour in C++, // so we may need to do the conversion manually instead to match the spec. volatile float f = static_cast<float>(x); return f; } inline double DoubleToInteger(double x) { if (std::isnan(x)) return 0; if (!std::isfinite(x) || x == 0) return x; return (x >= 0) ? std::floor(x) : std::ceil(x); } int32_t DoubleToInt32(double x) { int32_t i = FastD2I(x); if (FastI2D(i) == x) return i; Double d(x); int exponent = d.Exponent(); if (exponent < 0) { if (exponent <= -Double::kSignificandSize) return 0; return d.Sign() * static_cast<int32_t>(d.Significand() >> -exponent); } else { if (exponent > 31) return 0; return d.Sign() * static_cast<int32_t>(d.Significand() << exponent); } } bool DoubleToSmiInteger(double value, int* smi_int_value) { if (IsMinusZero(value)) return false; int i = FastD2IChecked(value); if (value != i || !Smi::IsValid(i)) return false; *smi_int_value = i; return true; } bool IsSmiDouble(double value) { return !IsMinusZero(value) && value >= Smi::kMinValue && value <= Smi::kMaxValue && value == FastI2D(FastD2I(value)); } bool IsInt32Double(double value) { return !IsMinusZero(value) && value >= kMinInt && value <= kMaxInt && value == FastI2D(FastD2I(value)); } bool IsUint32Double(double value) { return !IsMinusZero(value) && value >= 0 && value <= kMaxUInt32 && value == FastUI2D(FastD2UI(value)); } bool DoubleToUint32IfEqualToSelf(double value, uint32_t* uint32_value) { const double k2Pow52 = 4503599627370496.0; const uint32_t kValidTopBits = 0x43300000; const uint64_t kBottomBitMask = V8_2PART_UINT64_C(0x00000000, FFFFFFFF); // Add 2^52 to the double, to place valid uint32 values in the low-significant // bits of the exponent, by effectively setting the (implicit) top bit of the // significand. Note that this addition also normalises 0.0 and -0.0. double shifted_value = value + k2Pow52; // At this point, a valid uint32 valued double will be represented as: // // sign = 0 // exponent = 52 // significand = 1. 00...00 <value> // implicit^ ^^^^^^^ 32 bits // ^^^^^^^^^^^^^^^ 52 bits // // Therefore, we can first check the top 32 bits to make sure that the sign, // exponent and remaining significand bits are valid, and only then check the // value in the bottom 32 bits. uint64_t result = bit_cast<uint64_t>(shifted_value); if ((result >> 32) == kValidTopBits) { *uint32_value = result & kBottomBitMask; return FastUI2D(result & kBottomBitMask) == value; } return false; } int32_t NumberToInt32(Object* number) { if (number->IsSmi()) return Smi::cast(number)->value(); return DoubleToInt32(number->Number()); } uint32_t NumberToUint32(Object* number) { if (number->IsSmi()) return Smi::cast(number)->value(); return DoubleToUint32(number->Number()); } uint32_t PositiveNumberToUint32(Object* number) { if (number->IsSmi()) { int value = Smi::cast(number)->value(); if (value <= 0) return 0; return value; } DCHECK(number->IsHeapNumber()); double value = number->Number(); // Catch all values smaller than 1 and use the double-negation trick for NANs. if (!(value >= 1)) return 0; uint32_t max = std::numeric_limits<uint32_t>::max(); if (value < max) return static_cast<uint32_t>(value); return max; } int64_t NumberToInt64(Object* number) { if (number->IsSmi()) return Smi::cast(number)->value(); return static_cast<int64_t>(number->Number()); } bool TryNumberToSize(Object* number, size_t* result) { // Do not create handles in this function! Don't use SealHandleScope because // the function can be used concurrently. if (number->IsSmi()) { int value = Smi::cast(number)->value(); DCHECK(static_cast<unsigned>(Smi::kMaxValue) <= std::numeric_limits<size_t>::max()); if (value >= 0) { *result = static_cast<size_t>(value); return true; } return false; } else { DCHECK(number->IsHeapNumber()); double value = HeapNumber::cast(number)->value(); // If value is compared directly to the limit, the limit will be // casted to a double and could end up as limit + 1, // because a double might not have enough mantissa bits for it. // So we might as well cast the limit first, and use < instead of <=. double maxSize = static_cast<double>(std::numeric_limits<size_t>::max()); if (value >= 0 && value < maxSize) { *result = static_cast<size_t>(value); return true; } else { return false; } } } size_t NumberToSize(Object* number) { size_t result = 0; bool is_valid = TryNumberToSize(number, &result); CHECK(is_valid); return result; } uint32_t DoubleToUint32(double x) { return static_cast<uint32_t>(DoubleToInt32(x)); } template <class Iterator, class EndMark> bool SubStringEquals(Iterator* current, EndMark end, const char* substring) { DCHECK(**current == *substring); for (substring++; *substring != '\0'; substring++) { ++*current; if (*current == end || **current != *substring) return false; } ++*current; return true; } // Returns true if a nonspace character has been found and false if the // end was been reached before finding a nonspace character. template <class Iterator, class EndMark> inline bool AdvanceToNonspace(UnicodeCache* unicode_cache, Iterator* current, EndMark end) { while (*current != end) { if (!unicode_cache->IsWhiteSpaceOrLineTerminator(**current)) return true; ++*current; } return false; } // Parsing integers with radix 2, 4, 8, 16, 32. Assumes current != end. template <int radix_log_2, class Iterator, class EndMark> double InternalStringToIntDouble(UnicodeCache* unicode_cache, Iterator current, EndMark end, bool negative, bool allow_trailing_junk) { DCHECK(current != end); // Skip leading 0s. while (*current == '0') { ++current; if (current == end) return SignedZero(negative); } int64_t number = 0; int exponent = 0; const int radix = (1 << radix_log_2); do { int digit; if (*current >= '0' && *current <= '9' && *current < '0' + radix) { digit = static_cast<char>(*current) - '0'; } else if (radix > 10 && *current >= 'a' && *current < 'a' + radix - 10) { digit = static_cast<char>(*current) - 'a' + 10; } else if (radix > 10 && *current >= 'A' && *current < 'A' + radix - 10) { digit = static_cast<char>(*current) - 'A' + 10; } else { if (allow_trailing_junk || !AdvanceToNonspace(unicode_cache, ¤t, end)) { break; } else { return JunkStringValue(); } } number = number * radix + digit; int overflow = static_cast<int>(number >> 53); if (overflow != 0) { // Overflow occurred. Need to determine which direction to round the // result. int overflow_bits_count = 1; while (overflow > 1) { overflow_bits_count++; overflow >>= 1; } int dropped_bits_mask = ((1 << overflow_bits_count) - 1); int dropped_bits = static_cast<int>(number) & dropped_bits_mask; number >>= overflow_bits_count; exponent = overflow_bits_count; bool zero_tail = true; while (true) { ++current; if (current == end || !isDigit(*current, radix)) break; zero_tail = zero_tail && *current == '0'; exponent += radix_log_2; } if (!allow_trailing_junk && AdvanceToNonspace(unicode_cache, ¤t, end)) { return JunkStringValue(); } int middle_value = (1 << (overflow_bits_count - 1)); if (dropped_bits > middle_value) { number++; // Rounding up. } else if (dropped_bits == middle_value) { // Rounding to even to consistency with decimals: half-way case rounds // up if significant part is odd and down otherwise. if ((number & 1) != 0 || !zero_tail) { number++; // Rounding up. } } // Rounding up may cause overflow. if ((number & (static_cast<int64_t>(1) << 53)) != 0) { exponent++; number >>= 1; } break; } ++current; } while (current != end); DCHECK(number < ((int64_t)1 << 53)); DCHECK(static_cast<int64_t>(static_cast<double>(number)) == number); if (exponent == 0) { if (negative) { if (number == 0) return -0.0; number = -number; } return static_cast<double>(number); } DCHECK(number != 0); return std::ldexp(static_cast<double>(negative ? -number : number), exponent); } // ES6 18.2.5 parseInt(string, radix) template <class Iterator, class EndMark> double InternalStringToInt(UnicodeCache* unicode_cache, Iterator current, EndMark end, int radix) { const bool allow_trailing_junk = true; const double empty_string_val = JunkStringValue(); if (!AdvanceToNonspace(unicode_cache, ¤t, end)) { return empty_string_val; } bool negative = false; bool leading_zero = false; if (*current == '+') { // Ignore leading sign; skip following spaces. ++current; if (current == end) { return JunkStringValue(); } } else if (*current == '-') { ++current; if (current == end) { return JunkStringValue(); } negative = true; } if (radix == 0) { // Radix detection. radix = 10; if (*current == '0') { ++current; if (current == end) return SignedZero(negative); if (*current == 'x' || *current == 'X') { radix = 16; ++current; if (current == end) return JunkStringValue(); } else { leading_zero = true; } } } else if (radix == 16) { if (*current == '0') { // Allow "0x" prefix. ++current; if (current == end) return SignedZero(negative); if (*current == 'x' || *current == 'X') { ++current; if (current == end) return JunkStringValue(); } else { leading_zero = true; } } } if (radix < 2 || radix > 36) return JunkStringValue(); // Skip leading zeros. while (*current == '0') { leading_zero = true; ++current; if (current == end) return SignedZero(negative); } if (!leading_zero && !isDigit(*current, radix)) { return JunkStringValue(); } if (base::bits::IsPowerOfTwo32(radix)) { switch (radix) { case 2: return InternalStringToIntDouble<1>( unicode_cache, current, end, negative, allow_trailing_junk); case 4: return InternalStringToIntDouble<2>( unicode_cache, current, end, negative, allow_trailing_junk); case 8: return InternalStringToIntDouble<3>( unicode_cache, current, end, negative, allow_trailing_junk); case 16: return InternalStringToIntDouble<4>( unicode_cache, current, end, negative, allow_trailing_junk); case 32: return InternalStringToIntDouble<5>( unicode_cache, current, end, negative, allow_trailing_junk); default: UNREACHABLE(); } } if (radix == 10) { // Parsing with strtod. const int kMaxSignificantDigits = 309; // Doubles are less than 1.8e308. // The buffer may contain up to kMaxSignificantDigits + 1 digits and a zero // end. const int kBufferSize = kMaxSignificantDigits + 2; char buffer[kBufferSize]; int buffer_pos = 0; while (*current >= '0' && *current <= '9') { if (buffer_pos <= kMaxSignificantDigits) { // If the number has more than kMaxSignificantDigits it will be parsed // as infinity. DCHECK(buffer_pos < kBufferSize); buffer[buffer_pos++] = static_cast<char>(*current); } ++current; if (current == end) break; } if (!allow_trailing_junk && AdvanceToNonspace(unicode_cache, ¤t, end)) { return JunkStringValue(); } SLOW_DCHECK(buffer_pos < kBufferSize); buffer[buffer_pos] = '\0'; Vector<const char> buffer_vector(buffer, buffer_pos); return negative ? -Strtod(buffer_vector, 0) : Strtod(buffer_vector, 0); } // The following code causes accumulating rounding error for numbers greater // than ~2^56. It's explicitly allowed in the spec: "if R is not 2, 4, 8, 10, // 16, or 32, then mathInt may be an implementation-dependent approximation to // the mathematical integer value" (15.1.2.2). int lim_0 = '0' + (radix < 10 ? radix : 10); int lim_a = 'a' + (radix - 10); int lim_A = 'A' + (radix - 10); // NOTE: The code for computing the value may seem a bit complex at // first glance. It is structured to use 32-bit multiply-and-add // loops as long as possible to avoid loosing precision. double v = 0.0; bool done = false; do { // Parse the longest part of the string starting at index j // possible while keeping the multiplier, and thus the part // itself, within 32 bits. unsigned int part = 0, multiplier = 1; while (true) { int d; if (*current >= '0' && *current < lim_0) { d = *current - '0'; } else if (*current >= 'a' && *current < lim_a) { d = *current - 'a' + 10; } else if (*current >= 'A' && *current < lim_A) { d = *current - 'A' + 10; } else { done = true; break; } // Update the value of the part as long as the multiplier fits // in 32 bits. When we can't guarantee that the next iteration // will not overflow the multiplier, we stop parsing the part // by leaving the loop. const unsigned int kMaximumMultiplier = 0xffffffffU / 36; uint32_t m = multiplier * radix; if (m > kMaximumMultiplier) break; part = part * radix + d; multiplier = m; DCHECK(multiplier > part); ++current; if (current == end) { done = true; break; } } // Update the value and skip the part in the string. v = v * multiplier + part; } while (!done); if (!allow_trailing_junk && AdvanceToNonspace(unicode_cache, ¤t, end)) { return JunkStringValue(); } return negative ? -v : v; } // Converts a string to a double value. Assumes the Iterator supports // the following operations: // 1. current == end (other ops are not allowed), current != end. // 2. *current - gets the current character in the sequence. // 3. ++current (advances the position). template <class Iterator, class EndMark> double InternalStringToDouble(UnicodeCache* unicode_cache, Iterator current, EndMark end, int flags, double empty_string_val) { // To make sure that iterator dereferencing is valid the following // convention is used: // 1. Each '++current' statement is followed by check for equality to 'end'. // 2. If AdvanceToNonspace returned false then current == end. // 3. If 'current' becomes be equal to 'end' the function returns or goes to // 'parsing_done'. // 4. 'current' is not dereferenced after the 'parsing_done' label. // 5. Code before 'parsing_done' may rely on 'current != end'. if (!AdvanceToNonspace(unicode_cache, ¤t, end)) { return empty_string_val; } const bool allow_trailing_junk = (flags & ALLOW_TRAILING_JUNK) != 0; // The longest form of simplified number is: "-<significant digits>'.1eXXX\0". const int kBufferSize = kMaxSignificantDigits + 10; char buffer[kBufferSize]; // NOLINT: size is known at compile time. int buffer_pos = 0; // Exponent will be adjusted if insignificant digits of the integer part // or insignificant leading zeros of the fractional part are dropped. int exponent = 0; int significant_digits = 0; int insignificant_digits = 0; bool nonzero_digit_dropped = false; enum Sign { NONE, NEGATIVE, POSITIVE }; Sign sign = NONE; if (*current == '+') { // Ignore leading sign. ++current; if (current == end) return JunkStringValue(); sign = POSITIVE; } else if (*current == '-') { ++current; if (current == end) return JunkStringValue(); sign = NEGATIVE; } static const char kInfinityString[] = "Infinity"; if (*current == kInfinityString[0]) { if (!SubStringEquals(¤t, end, kInfinityString)) { return JunkStringValue(); } if (!allow_trailing_junk && AdvanceToNonspace(unicode_cache, ¤t, end)) { return JunkStringValue(); } DCHECK(buffer_pos == 0); return (sign == NEGATIVE) ? -V8_INFINITY : V8_INFINITY; } bool leading_zero = false; if (*current == '0') { ++current; if (current == end) return SignedZero(sign == NEGATIVE); leading_zero = true; // It could be hexadecimal value. if ((flags & ALLOW_HEX) && (*current == 'x' || *current == 'X')) { ++current; if (current == end || !isDigit(*current, 16) || sign != NONE) { return JunkStringValue(); // "0x". } return InternalStringToIntDouble<4>(unicode_cache, current, end, false, allow_trailing_junk); // It could be an explicit octal value. } else if ((flags & ALLOW_OCTAL) && (*current == 'o' || *current == 'O')) { ++current; if (current == end || !isDigit(*current, 8) || sign != NONE) { return JunkStringValue(); // "0o". } return InternalStringToIntDouble<3>(unicode_cache, current, end, false, allow_trailing_junk); // It could be a binary value. } else if ((flags & ALLOW_BINARY) && (*current == 'b' || *current == 'B')) { ++current; if (current == end || !isBinaryDigit(*current) || sign != NONE) { return JunkStringValue(); // "0b". } return InternalStringToIntDouble<1>(unicode_cache, current, end, false, allow_trailing_junk); } // Ignore leading zeros in the integer part. while (*current == '0') { ++current; if (current == end) return SignedZero(sign == NEGATIVE); } } bool octal = leading_zero && (flags & ALLOW_IMPLICIT_OCTAL) != 0; // Copy significant digits of the integer part (if any) to the buffer. while (*current >= '0' && *current <= '9') { if (significant_digits < kMaxSignificantDigits) { DCHECK(buffer_pos < kBufferSize); buffer[buffer_pos++] = static_cast<char>(*current); significant_digits++; // Will later check if it's an octal in the buffer. } else { insignificant_digits++; // Move the digit into the exponential part. nonzero_digit_dropped = nonzero_digit_dropped || *current != '0'; } octal = octal && *current < '8'; ++current; if (current == end) goto parsing_done; } if (significant_digits == 0) { octal = false; } if (*current == '.') { if (octal && !allow_trailing_junk) return JunkStringValue(); if (octal) goto parsing_done; ++current; if (current == end) { if (significant_digits == 0 && !leading_zero) { return JunkStringValue(); } else { goto parsing_done; } } if (significant_digits == 0) { // octal = false; // Integer part consists of 0 or is absent. Significant digits start after // leading zeros (if any). while (*current == '0') { ++current; if (current == end) return SignedZero(sign == NEGATIVE); exponent--; // Move this 0 into the exponent. } } // There is a fractional part. We don't emit a '.', but adjust the exponent // instead. while (*current >= '0' && *current <= '9') { if (significant_digits < kMaxSignificantDigits) { DCHECK(buffer_pos < kBufferSize); buffer[buffer_pos++] = static_cast<char>(*current); significant_digits++; exponent--; } else { // Ignore insignificant digits in the fractional part. nonzero_digit_dropped = nonzero_digit_dropped || *current != '0'; } ++current; if (current == end) goto parsing_done; } } if (!leading_zero && exponent == 0 && significant_digits == 0) { // If leading_zeros is true then the string contains zeros. // If exponent < 0 then string was [+-]\.0*... // If significant_digits != 0 the string is not equal to 0. // Otherwise there are no digits in the string. return JunkStringValue(); } // Parse exponential part. if (*current == 'e' || *current == 'E') { if (octal) return JunkStringValue(); ++current; if (current == end) { if (allow_trailing_junk) { goto parsing_done; } else { return JunkStringValue(); } } char sign = '+'; if (*current == '+' || *current == '-') { sign = static_cast<char>(*current); ++current; if (current == end) { if (allow_trailing_junk) { goto parsing_done; } else { return JunkStringValue(); } } } if (current == end || *current < '0' || *current > '9') { if (allow_trailing_junk) { goto parsing_done; } else { return JunkStringValue(); } } const int max_exponent = INT_MAX / 2; DCHECK(-max_exponent / 2 <= exponent && exponent <= max_exponent / 2); int num = 0; do { // Check overflow. int digit = *current - '0'; if (num >= max_exponent / 10 && !(num == max_exponent / 10 && digit <= max_exponent % 10)) { num = max_exponent; } else { num = num * 10 + digit; } ++current; } while (current != end && *current >= '0' && *current <= '9'); exponent += (sign == '-' ? -num : num); } if (!allow_trailing_junk && AdvanceToNonspace(unicode_cache, ¤t, end)) { return JunkStringValue(); } parsing_done: exponent += insignificant_digits; if (octal) { return InternalStringToIntDouble<3>(unicode_cache, buffer, buffer + buffer_pos, sign == NEGATIVE, allow_trailing_junk); } if (nonzero_digit_dropped) { buffer[buffer_pos++] = '1'; exponent--; } SLOW_DCHECK(buffer_pos < kBufferSize); buffer[buffer_pos] = '\0'; double converted = Strtod(Vector<const char>(buffer, buffer_pos), exponent); return (sign == NEGATIVE) ? -converted : converted; } } // namespace internal } // namespace v8 #endif // V8_CONVERSIONS_INL_H_