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Differential D130032

[libc] fix strtofloatingpoint on rare edge case
ClosedPublic

Authored by michaelrj on Jul 18 2022, 11:36 AM.

Details

Reviewers
sivachandra
lntue
Commits
rGbf7f01d857ed: [libc] fix strtofloatingpoint on rare edge case
Summary

Currently, there are two string parsers that can be used in a call to
strtofloatingpoint. There is the main parser used by Clinger's fast path
and Eisel-Lemire, and the backup parser used by Simple Decimal
Conversion. There was a bug in the backup parser where if the number had
more than 800 digits (the size of the SDC buffer) before the decimal
point, it would just ignore the digits after the 800th and not count
them into the exponent. This patch fixes that issue and adds regression
tests.

Diff Detail

Event Timeline

michaelrj created this revision.Jul 18 2022, 11:36 AM
Herald added projects: Restricted Project, Restricted Project. · View Herald TranscriptJul 18 2022, 11:36 AM
Herald added subscribers: libc-commits, ecnelises, tschuett. · View Herald Transcript
michaelrj requested review of this revision.Jul 18 2022, 11:36 AM
lntue accepted this revision.Jul 18 2022, 11:46 AM
This revision is now accepted and ready to land.Jul 18 2022, 11:46 AM
michaelrj updated this revision to Diff 445587.Jul 18 2022, 11:53 AM

fix another small bug (leading zeroes were being counted as digits despite not affecting the actual number) and remove the test case from the comparison test data.

lntue accepted this revision.Jul 18 2022, 12:49 PM
Harbormaster completed remote builds in B176088: Diff 445587.Jul 18 2022, 1:10 PM
Closed by commit rGbf7f01d857ed: [libc] fix strtofloatingpoint on rare edge case (authored by michaelrj). · Explain WhyJul 18 2022, 2:23 PM
This revision was automatically updated to reflect the committed changes.
michaelrj added a commit: rGbf7f01d857ed: [libc] fix strtofloatingpoint on rare edge case.

Revision Contents

PathSize
libc/
src/
__support/
11 lines
test/
src/
stdlib/
98 lines

Diff 445627

libc/src/__support/high_precision_decimal.h

Show First 20 Lines • Show All 279 Lines • ▼ Show 20 Lines void left_shift(uint32_t shiftAmount) {
this->trim_trailing_zeroes(); this->trim_trailing_zeroes();
} }
public: public:
// numString is assumed to be a string of numeric characters. It doesn't // numString is assumed to be a string of numeric characters. It doesn't
// handle leading spaces. // handle leading spaces.
HighPrecisionDecimal(const char *__restrict numString) { HighPrecisionDecimal(const char *__restrict numString) {
bool saw_dot = false; bool saw_dot = false;
// This counts the digits in the number, even if there isn't space to store
// them all.
uint32_t total_digits = 0;
while (isdigit(*numString) || *numString == '.') { while (isdigit(*numString) || *numString == '.') {
if (*numString == '.') { if (*numString == '.') {
if (saw_dot) { if (saw_dot) {
break; break;
} }
this->decimal_point = this->num_digits; this->decimal_point = total_digits;
saw_dot = true; saw_dot = true;
} else { } else {
if (*numString == '0' && this->num_digits == 0) { if (*numString == '0' && this->num_digits == 0) {
--this->decimal_point; --this->decimal_point;
++numString; ++numString;
continue; continue;
} }
++total_digits;
if (this->num_digits < MAX_NUM_DIGITS) { if (this->num_digits < MAX_NUM_DIGITS) {
this->digits[this->num_digits] = this->digits[this->num_digits] =
static_cast<uint8_t>(*numString - '0'); static_cast<uint8_t>(*numString - '0');
++this->num_digits; ++this->num_digits;
} else if (*numString != '0') { } else if (*numString != '0') {
this->truncated = true; this->truncated = true;
} }
} }
++numString; ++numString;
} }
if (!saw_dot) { if (!saw_dot)
this->decimal_point = this->num_digits; this->decimal_point = total_digits;
}
if ((*numString | 32) == 'e') { if ((*numString | 32) == 'e') {
++numString; ++numString;
if (isdigit(*numString) || *numString == '+' || *numString == '-') { if (isdigit(*numString) || *numString == '+' || *numString == '-') {
int32_t add_to_exp = strtointeger<int32_t>(numString, nullptr, 10); int32_t add_to_exp = strtointeger<int32_t>(numString, nullptr, 10);
if (add_to_exp > 100000) { if (add_to_exp > 100000) {
add_to_exp = 100000; add_to_exp = 100000;
} else if (add_to_exp < -100000) { } else if (add_to_exp < -100000) {
▲ Show 20 Lines • Show All 67 Lines • Show Last 20 Lines

libc/test/src/stdlib/strtod_test.cpp

Show First 20 Lines • Show All 74 Lines • ▼ Show 20 Lines
// These are tests that have caused problems in the past. // These are tests that have caused problems in the past.
TEST_F(LlvmLibcStrToDTest, SpecificFailures) { TEST_F(LlvmLibcStrToDTest, SpecificFailures) {
run_test("3E70000000000000", 16, uint64_t(0x7FF0000000000000), ERANGE); run_test("3E70000000000000", 16, uint64_t(0x7FF0000000000000), ERANGE);
run_test("358416272e-33", 13, uint64_t(0x3adbbb2a68c9d0b9)); run_test("358416272e-33", 13, uint64_t(0x3adbbb2a68c9d0b9));
run_test("2.16656806400000023841857910156251e9", 36, run_test("2.16656806400000023841857910156251e9", 36,
uint64_t(0x41e0246690000001)); uint64_t(0x41e0246690000001));
run_test("27949676547093071875", 20, uint64_t(0x43f83e132bc608c9)); run_test("27949676547093071875", 20, uint64_t(0x43f83e132bc608c9));
run_test(
"100000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000e-800",
806, 0x3ff0000000000000);
run_test(
"100000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000e-799",
806, 0x4024000000000000);
run_test(
"100000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"0000000000e-800",
807, 0x4024000000000000);
run_test(
"10000000000000000000000000000000000000000000000000000000000000000e-64",
69, 0x3ff0000000000000);
run_test(
"100000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000e-128",
134, 0x3ff0000000000000);
run_test("1000000000000000000000000000000000000000000000000000000000000000000"
"0000000000000000000000000000000000000000000000000000000000000000000"
"0000000000000000000000000000000000000000000000000000000000000000000"
"00000000000000000000000000000000000000000000000000000000e-256",
262, 0x3ff0000000000000);
run_test("1000000000000000000000000000000000000000000000000000000000000000000"
"0000000000000000000000000000000000000000000000000000000000000000000"
"0000000000000000000000000000000000000000000000000000000000000000000"
"0000000000000000000000000000000000000000000000000000000000000000000"
"0000000000000000000000000000000000000000000000000000000000000000000"
"0000000000000000000000000000000000000000000000000000000000000000000"
"0000000000000000000000000000000000000000000000000000000000000000000"
"00000000000000000000000000000000000000000000e-512",
518, 0x3ff0000000000000);
run_test(
"100000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"00000000000000000e-1024",
1031, 0x3ff0000000000000);
run_test(
"0"
"100000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"000000000000000000000000000000000000000000000000000000000000000000000000"
"00000000000000000e-1024",
1032, 0x3ff0000000000000);
} }
TEST_F(LlvmLibcStrToDTest, FuzzFailures) { TEST_F(LlvmLibcStrToDTest, FuzzFailures) {
run_test("-\xff\xff\xff\xff\xff\xff\xff\x01", 0, uint64_t(0)); run_test("-\xff\xff\xff\xff\xff\xff\xff\x01", 0, uint64_t(0));
run_test("-.????", 0, uint64_t(0)); run_test("-.????", 0, uint64_t(0));
run_test( run_test(
"44444444444444444444444444444444444444444444444444A44444444444444444" "44444444444444444444444444444444444444444444444444A44444444444444444"
"44444444444*\x99\xff\xff\xff\xff", "44444444444*\x99\xff\xff\xff\xff",
50, uint64_t(0x4a3e68fdd0e0b2d8)); 50, uint64_t(0x4a3e68fdd0e0b2d8));
run_test("-NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNKNNNNNNNNNNNNNNNNNN?" run_test("-NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNKNNNNNNNNNNNNNNNNNN?"
"NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN?", "NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN?",
0, uint64_t(0)); 0, uint64_t(0));
run_test("0x.666E40", 9, uint64_t(0x3fd99b9000000000)); run_test("0x.666E40", 9, uint64_t(0x3fd99b9000000000));
} }