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Commit 2b226c59 authored by floitschV8@gmail.com's avatar floitschV8@gmail.com
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Weed out extreme exponents in strtod. 

If a decimal exponent is less than -309 return 0.0.
If a decimal exponent is greater than +324 return +infinity.

BUG=
TEST=

Review URL: http://codereview.chromium.org/3519017

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5623 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
parent d5ac5658
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Showing with 113 additions and 32 deletions
src/conversions.cc
View file @ 2b226c59
......@@ -353,7 +353,7 @@ static double InternalStringToInt(Iterator current, EndMark end, int radix) {
ASSERT(buffer_pos < kBufferSize);
buffer[buffer_pos] = '\0';
Vector<char> buffer_vector(buffer, buffer_pos);
Vector<const char> buffer_vector(buffer, buffer_pos);
return sign ? -Strtod(buffer_vector, 0) : Strtod(buffer_vector, 0);
}
......@@ -653,7 +653,7 @@ static double InternalStringToDouble(Iterator current,
ASSERT(buffer_pos < kBufferSize);
buffer[buffer_pos] = '\0';
double converted = Strtod(Vector<char>(buffer, buffer_pos), exponent);
double converted = Strtod(Vector<const char>(buffer, buffer_pos), exponent);
return sign? -converted: converted;
}
......
src/strtod.cc
View file @ 2b226c59
......@@ -43,6 +43,14 @@ static const int kMaxExactDoubleIntegerDecimalDigits = 15;
// 2^64 = 18446744073709551616
// Any integer with at most 19 digits will hence fit into a 64bit datatype.
static const int kMaxUint64DecimalDigits = 19;
// Max double: 1.7976931348623157 x 10^308
// Min non-zero double: 4.9406564584124654 x 10^-324
// Any x >= 10^309 is interpreted as +infinity.
// Any x <= 10^-324 is interpreted as 0.
// Note that 2.5e-324 (despite being smaller than the min double) will be read
// as non-zero (equal to the min non-zero double).
static const int kMaxDecimalPower = 309;
static const int kMinDecimalPower = -324;
static const double exact_powers_of_ten[] = {
1.0, // 10^0
......@@ -76,26 +84,50 @@ static const int kExactPowersOfTenSize = ARRAY_SIZE(exact_powers_of_ten);
extern "C" double gay_strtod(const char* s00, const char** se);
static double old_strtod(Vector<char> buffer, int exponent) {
static double old_strtod(Vector<const char> buffer, int exponent) {
char gay_buffer[1024];
Vector<char> gay_buffer_vector(gay_buffer, sizeof(gay_buffer));
buffer.start()[buffer.length()] = '\0';
OS::SNPrintF(gay_buffer_vector, "%se%d", buffer.start(), exponent);
int pos = 0;
for (int i = 0; i < buffer.length(); ++i) {
gay_buffer_vector[pos++] = buffer[i];
}
gay_buffer_vector[pos++] = 'e';
if (exponent < 0) {
gay_buffer_vector[pos++] = '-';
exponent = -exponent;
}
const int kNumberOfExponentDigits = 5;
for (int i = kNumberOfExponentDigits - 1; i >= 0; i--) {
gay_buffer_vector[pos + i] = exponent % 10 + '0';
exponent /= 10;
}
pos += kNumberOfExponentDigits;
gay_buffer_vector[pos] = '\0';
return gay_strtod(gay_buffer, NULL);
}
static Vector<char> TrimTrailingZeros(Vector<char> buffer) {
static Vector<const char> TrimLeadingZeros(Vector<const char> buffer) {
for (int i = 0; i < buffer.length(); i++) {
if (buffer[i] != '0') {
return Vector<const char>(buffer.start() + i, buffer.length() - i);
}
}
return Vector<const char>(buffer.start(), 0);
}
static Vector<const char> TrimTrailingZeros(Vector<const char> buffer) {
for (int i = buffer.length() - 1; i >= 0; --i) {
if (buffer[i] != '0') {
return Vector<char>(buffer.start(), i + 1);
return Vector<const char>(buffer.start(), i + 1);
}
}
return Vector<char>(buffer.start(), 0);
return Vector<const char>(buffer.start(), 0);
}
uint64_t ReadUint64(Vector<char> buffer) {
uint64_t ReadUint64(Vector<const char> buffer) {
ASSERT(buffer.length() <= kMaxUint64DecimalDigits);
uint64_t result = 0;
for (int i = 0; i < buffer.length(); ++i) {
......@@ -107,10 +139,13 @@ uint64_t ReadUint64(Vector<char> buffer) {
}
double Strtod(Vector<char> buffer, int exponent) {
Vector<char> trimmed = TrimTrailingZeros(buffer);
double Strtod(Vector<const char> buffer, int exponent) {
Vector<const char> left_trimmed = TrimLeadingZeros(buffer);
Vector<const char> trimmed = TrimTrailingZeros(left_trimmed);
exponent += left_trimmed.length() - trimmed.length();
if (trimmed.length() == 0) return 0.0;
exponent += buffer.length() - trimmed.length();
if (exponent + trimmed.length() - 1 >= kMaxDecimalPower) return V8_INFINITY;
if (exponent + trimmed.length() <= kMinDecimalPower) return 0.0;
if (trimmed.length() <= kMaxExactDoubleIntegerDecimalDigits) {
// The trimmed input fits into a double.
// If the 10^exponent (resp. 10^-exponent) fits into a double too then we
......
src/strtod.h
View file @ 2b226c59
......@@ -33,7 +33,7 @@ namespace internal {
// The buffer must only contain digits in the range [0-9]. It must not
// contain a dot or a sign. It must not start with '0', and must not be empty.
double Strtod(Vector<char> buffer, int exponent);
double Strtod(Vector<const char> buffer, int exponent);
} } // namespace v8::internal
......
test/cctest/test-strtod.cc
View file @ 2b226c59
......@@ -4,30 +4,32 @@
#include "v8.h"
#include "platform.h"
#include "cctest.h"
#include "strtod.h"
using namespace v8::internal;
static const int kBufferSize = 100;
static Vector<const char> StringToVector(const char* str) {
return Vector<const char>(str, StrLength(str));
}
static double StrtodChar(const char* str, int exponent) {
return Strtod(StringToVector(str), exponent);
}
TEST(Strtod) {
char buffer_array[kBufferSize];
Vector<char> buffer(buffer_array, kBufferSize);
Vector<char> vector;
Vector<const char> vector;
OS::StrNCpy(buffer, "0", kBufferSize);
vector = Vector<char>(buffer_array, strlen(buffer_array));
vector = StringToVector("0");
CHECK_EQ(0.0, Strtod(vector, 1));
CHECK_EQ(0.0, Strtod(vector, 2));
CHECK_EQ(0.0, Strtod(vector, -2));
CHECK_EQ(0.0, Strtod(vector, -999));
CHECK_EQ(0.0, Strtod(vector, +999));
OS::StrNCpy(buffer, "1", kBufferSize);
vector = Vector<char>(buffer_array, strlen(buffer_array));
vector = StringToVector("1");
CHECK_EQ(1.0, Strtod(vector, 0));
CHECK_EQ(10.0, Strtod(vector, 1));
CHECK_EQ(100.0, Strtod(vector, 2));
......@@ -46,8 +48,7 @@ TEST(Strtod) {
CHECK_EQ(1e-25, Strtod(vector, -25));
CHECK_EQ(1e-39, Strtod(vector, -39));
OS::StrNCpy(buffer, "2", kBufferSize);
vector = Vector<char>(buffer_array, strlen(buffer_array));
vector = StringToVector("2");
CHECK_EQ(2.0, Strtod(vector, 0));
CHECK_EQ(20.0, Strtod(vector, 1));
CHECK_EQ(200.0, Strtod(vector, 2));
......@@ -66,8 +67,7 @@ TEST(Strtod) {
CHECK_EQ(2e-25, Strtod(vector, -25));
CHECK_EQ(2e-39, Strtod(vector, -39));
OS::StrNCpy(buffer, "9", kBufferSize);
vector = Vector<char>(buffer_array, strlen(buffer_array));
vector = StringToVector("9");
CHECK_EQ(9.0, Strtod(vector, 0));
CHECK_EQ(90.0, Strtod(vector, 1));
CHECK_EQ(900.0, Strtod(vector, 2));
......@@ -86,8 +86,7 @@ TEST(Strtod) {
CHECK_EQ(9e-25, Strtod(vector, -25));
CHECK_EQ(9e-39, Strtod(vector, -39));
OS::StrNCpy(buffer, "12345", kBufferSize);
vector = Vector<char>(buffer_array, strlen(buffer_array));
vector = StringToVector("12345");
CHECK_EQ(12345.0, Strtod(vector, 0));
CHECK_EQ(123450.0, Strtod(vector, 1));
CHECK_EQ(1234500.0, Strtod(vector, 2));
......@@ -109,8 +108,7 @@ TEST(Strtod) {
CHECK_EQ(12345e-25, Strtod(vector, -25));
CHECK_EQ(12345e-39, Strtod(vector, -39));
OS::StrNCpy(buffer, "12345678901234", kBufferSize);
vector = Vector<char>(buffer_array, strlen(buffer_array));
vector = StringToVector("12345678901234");
CHECK_EQ(12345678901234.0, Strtod(vector, 0));
CHECK_EQ(123456789012340.0, Strtod(vector, 1));
CHECK_EQ(1234567890123400.0, Strtod(vector, 2));
......@@ -132,8 +130,7 @@ TEST(Strtod) {
CHECK_EQ(12345678901234e-25, Strtod(vector, -25));
CHECK_EQ(12345678901234e-39, Strtod(vector, -39));
OS::StrNCpy(buffer, "123456789012345", kBufferSize);
vector = Vector<char>(buffer_array, strlen(buffer_array));
vector = StringToVector("123456789012345");
CHECK_EQ(123456789012345.0, Strtod(vector, 0));
CHECK_EQ(1234567890123450.0, Strtod(vector, 1));
CHECK_EQ(12345678901234500.0, Strtod(vector, 2));
......@@ -152,4 +149,53 @@ TEST(Strtod) {
CHECK_EQ(123456789012345e-23, Strtod(vector, -23));
CHECK_EQ(123456789012345e-25, Strtod(vector, -25));
CHECK_EQ(123456789012345e-39, Strtod(vector, -39));
CHECK_EQ(0.0, StrtodChar("0", 12345));
CHECK_EQ(0.0, StrtodChar("", 1324));
CHECK_EQ(0.0, StrtodChar("000000000", 123));
CHECK_EQ(0.0, StrtodChar("2", -324));
CHECK_EQ(3e-324, StrtodChar("3", -324));
// It would be more readable to put non-zero literals on the left side (i.e.
// CHECK_EQ(1e-325, StrtodChar("1", -325))), but then Gcc complains that
// they are truncated to zero.
CHECK_EQ(0.0, StrtodChar("1", -325));
CHECK_EQ(0.0, StrtodChar("1", -325));
CHECK_EQ(0.0, StrtodChar("20000", -328));
CHECK_EQ(30000e-328, StrtodChar("30000", -328));
CHECK_EQ(0.0, StrtodChar("10000", -329));
CHECK_EQ(0.0, StrtodChar("90000", -329));
CHECK_EQ(0.0, StrtodChar("000000001", -325));
CHECK_EQ(0.0, StrtodChar("000000001", -325));
CHECK_EQ(0.0, StrtodChar("0000000020000", -328));
CHECK_EQ(30000e-328, StrtodChar("00000030000", -328));
CHECK_EQ(0.0, StrtodChar("0000000010000", -329));
CHECK_EQ(0.0, StrtodChar("0000000090000", -329));
// It would be more readable to put the literals (and not V8_INFINITY) on the
// left side (i.e. CHECK_EQ(1e309, StrtodChar("1", 309))), but then Gcc
// complains that the floating constant exceeds range of 'double'.
CHECK_EQ(V8_INFINITY, StrtodChar("1", 309));
CHECK_EQ(1e308, StrtodChar("1", 308));
CHECK_EQ(1234e305, StrtodChar("1234", 305));
CHECK_EQ(1234e304, StrtodChar("1234", 304));
CHECK_EQ(V8_INFINITY, StrtodChar("18", 307));
CHECK_EQ(17e307, StrtodChar("17", 307));
CHECK_EQ(V8_INFINITY, StrtodChar("0000001", 309));
CHECK_EQ(1e308, StrtodChar("00000001", 308));
CHECK_EQ(1234e305, StrtodChar("00000001234", 305));
CHECK_EQ(1234e304, StrtodChar("000000001234", 304));
CHECK_EQ(V8_INFINITY, StrtodChar("0000000018", 307));
CHECK_EQ(17e307, StrtodChar("0000000017", 307));
CHECK_EQ(V8_INFINITY, StrtodChar("1000000", 303));
CHECK_EQ(1e308, StrtodChar("100000", 303));
CHECK_EQ(1234e305, StrtodChar("123400000", 300));
CHECK_EQ(1234e304, StrtodChar("123400000", 299));
CHECK_EQ(V8_INFINITY, StrtodChar("180000000", 300));
CHECK_EQ(17e307, StrtodChar("170000000", 300));
CHECK_EQ(V8_INFINITY, StrtodChar("00000001000000", 303));
CHECK_EQ(1e308, StrtodChar("000000000000100000", 303));
CHECK_EQ(1234e305, StrtodChar("00000000123400000", 300));
CHECK_EQ(1234e304, StrtodChar("0000000123400000", 299));
CHECK_EQ(V8_INFINITY, StrtodChar("00000000180000000", 300));
CHECK_EQ(17e307, StrtodChar("00000000170000000", 300));
}
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