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v8/test/bigint/bigint-shell.cc
Jakob Kummerow 785e009eae [bigint][test] Better random input generation 
In addition to inputs consisting entirely of random bits, the
bigint test shell now also generates inputs that are powers of
two (i.e. have many 0-bits) and inputs with many 1-bits.
Empirically, these kinds of inputs are more likely to flush out
corner case bugs.

Bug: v8:11515
Change-Id: Ib69f12bf215055991b028196dc54ebbc00780bae
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3055292
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/main@{#76729}
2021-09-08 15:39:27 +00:00

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// Copyright 2021 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 <cmath>
#include <memory>
#include <string>
#include "src/bigint/bigint-internal.h"
#include "src/bigint/util.h"
namespace v8 {
namespace bigint {
namespace test {
int PrintHelp(char** argv) {
std::cerr << "Usage:\n"
<< argv[0] << " --help\n"
<< " Print this help and exit.\n"
<< argv[0] << " --list\n"
<< " List supported tests.\n"
<< argv[0] << " <testname>\n"
<< " Run the specified test (see --list for a list).\n"
<< "\nOptions when running tests:\n"
<< "--random-seed R\n"
<< " Initialize the random number generator with this seed.\n"
<< "--runs N\n"
<< " Repeat the test N times.\n";
return 1;
}
#define TESTS(V) \
V(kBarrett, "barrett") \
V(kBurnikel, "burnikel") \
V(kFFT, "fft") \
V(kFromString, "fromstring") \
V(kFromStringBase2, "fromstring2") \
V(kKaratsuba, "karatsuba") \
V(kToom, "toom") \
V(kToString, "tostring")
enum Operation { kNoOp, kList, kTest };
enum Test {
#define TEST(kName, name) kName,
TESTS(TEST)
#undef TEST
};
class RNG {
public:
RNG() = default;
void Initialize(int64_t seed) {
state0_ = MurmurHash3(static_cast<uint64_t>(seed));
state1_ = MurmurHash3(~state0_);
CHECK(state0_ != 0 || state1_ != 0);
}
uint64_t NextUint64() {
XorShift128(&state0_, &state1_);
return static_cast<uint64_t>(state0_ + state1_);
}
static inline void XorShift128(uint64_t* state0, uint64_t* state1) {
uint64_t s1 = *state0;
uint64_t s0 = *state1;
*state0 = s0;
s1 ^= s1 << 23;
s1 ^= s1 >> 17;
s1 ^= s0;
s1 ^= s0 >> 26;
*state1 = s1;
}
static uint64_t MurmurHash3(uint64_t h) {
h ^= h >> 33;
h *= uint64_t{0xFF51AFD7ED558CCD};
h ^= h >> 33;
h *= uint64_t{0xC4CEB9FE1A85EC53};
h ^= h >> 33;
return h;
}
private:
uint64_t state0_;
uint64_t state1_;
};
static constexpr int kCharsPerDigit = kDigitBits / 4;
static const char kConversionChars[] = "0123456789abcdefghijklmnopqrstuvwxyz";
std::string FormatHex(Digits X) {
X.Normalize();
if (X.len() == 0) return "0";
digit_t msd = X.msd();
const int msd_leading_zeros = CountLeadingZeros(msd);
const size_t bit_length = X.len() * kDigitBits - msd_leading_zeros;
const size_t chars = DIV_CEIL(bit_length, 4);
if (chars > 100000) {
return std::string("<BigInt with ") + std::to_string(bit_length) +
std::string(" bits>");
}
std::unique_ptr<char[]> result(new char[chars]);
for (size_t i = 0; i < chars; i++) result[i] = '?';
// Print the number into the string, starting from the last position.
int pos = static_cast<int>(chars - 1);
for (int i = 0; i < X.len() - 1; i++) {
digit_t d = X[i];
for (int j = 0; j < kCharsPerDigit; j++) {
result[pos--] = kConversionChars[d & 15];
d = static_cast<digit_t>(d >> 4u);
}
}
while (msd != 0) {
result[pos--] = kConversionChars[msd & 15];
msd = static_cast<digit_t>(msd >> 4u);
}
CHECK(pos == -1);
return std::string(result.get(), chars);
}
class Runner {
public:
Runner() = default;
void Initialize() {
rng_.Initialize(random_seed_);
processor_.reset(Processor::New(new Platform()));
}
ProcessorImpl* processor() {
return static_cast<ProcessorImpl*>(processor_.get());
}
int Run() {
if (op_ == kList) {
ListTests();
} else if (op_ == kTest) {
RunTest();
} else {
DCHECK(false); // Unreachable.
}
return 0;
}
void ListTests() {
#define PRINT(kName, name) std::cout << name << "\n";
TESTS(PRINT)
#undef PRINT
}
void AssertEquals(Digits input1, Digits input2, Digits expected,
Digits actual) {
if (Compare(expected, actual) == 0) return;
std::cerr << "Input 1: " << FormatHex(input1) << "\n";
std::cerr << "Input 2: " << FormatHex(input2) << "\n";
std::cerr << "Expected: " << FormatHex(expected) << "\n";
std::cerr << "Actual: " << FormatHex(actual) << "\n";
error_ = true;
}
void AssertEquals(Digits X, int radix, char* expected, int expected_length,
char* actual, int actual_length) {
if (expected_length == actual_length &&
std::memcmp(expected, actual, actual_length) == 0) {
return;
}
std::cerr << "Input: " << FormatHex(X) << "\n";
std::cerr << "Radix: " << radix << "\n";
std::cerr << "Expected: " << std::string(expected, expected_length) << "\n";
std::cerr << "Actual: " << std::string(actual, actual_length) << "\n";
error_ = true;
}
void AssertEquals(const char* input, int input_length, int radix,
Digits expected, Digits actual) {
if (Compare(expected, actual) == 0) return;
std::cerr << "Input: " << std::string(input, input_length) << "\n";
std::cerr << "Radix: " << radix << "\n";
std::cerr << "Expected: " << FormatHex(expected) << "\n";
std::cerr << "Actual: " << FormatHex(actual) << "\n";
error_ = true;
}
int RunTest() {
int count = 0;
if (test_ == kBarrett) {
for (int i = 0; i < runs_; i++) {
TestBarrett(&count);
}
} else if (test_ == kBurnikel) {
for (int i = 0; i < runs_; i++) {
TestBurnikel(&count);
}
} else if (test_ == kFFT) {
for (int i = 0; i < runs_; i++) {
TestFFT(&count);
}
} else if (test_ == kKaratsuba) {
for (int i = 0; i < runs_; i++) {
TestKaratsuba(&count);
}
} else if (test_ == kToom) {
for (int i = 0; i < runs_; i++) {
TestToom(&count);
}
} else if (test_ == kToString) {
for (int i = 0; i < runs_; i++) {
TestToString(&count);
}
} else if (test_ == kFromString) {
for (int i = 0; i < runs_; i++) {
TestFromString(&count);
}
} else if (test_ == kFromStringBase2) {
for (int i = 0; i < runs_; i++) {
TestFromStringBaseTwo(&count);
}
} else {
DCHECK(false); // Unreachable.
}
if (error_) return 1;
std::cout << count << " tests run, no error reported.\n";
return 0;
}
void TestKaratsuba(int* count) {
// Calling {MultiplyKaratsuba} directly is only valid if
// left_size >= right_size and right_size >= kKaratsubaThreshold.
constexpr int kMin = kKaratsubaThreshold;
constexpr int kMax = 3 * kKaratsubaThreshold;
for (int right_size = kMin; right_size <= kMax; right_size++) {
for (int left_size = right_size; left_size <= kMax; left_size++) {
ScratchDigits A(left_size);
ScratchDigits B(right_size);
int result_len = MultiplyResultLength(A, B);
ScratchDigits result(result_len);
ScratchDigits result_schoolbook(result_len);
GenerateRandom(A);
GenerateRandom(B);
processor()->MultiplyKaratsuba(result, A, B);
processor()->MultiplySchoolbook(result_schoolbook, A, B);
AssertEquals(A, B, result_schoolbook, result);
if (error_) return;
(*count)++;
}
}
}
void TestToom(int* count) {
#if V8_ADVANCED_BIGINT_ALGORITHMS
// {MultiplyToomCook} works fine even below the threshold, so we can
// save some time by starting small.
constexpr int kMin = kToomThreshold - 60;
constexpr int kMax = kToomThreshold + 10;
for (int right_size = kMin; right_size <= kMax; right_size++) {
for (int left_size = right_size; left_size <= kMax; left_size++) {
ScratchDigits A(left_size);
ScratchDigits B(right_size);
int result_len = MultiplyResultLength(A, B);
ScratchDigits result(result_len);
ScratchDigits result_karatsuba(result_len);
GenerateRandom(A);
GenerateRandom(B);
processor()->MultiplyToomCook(result, A, B);
// Using Karatsuba as reference.
processor()->MultiplyKaratsuba(result_karatsuba, A, B);
AssertEquals(A, B, result_karatsuba, result);
if (error_) return;
(*count)++;
}
}
#endif // V8_ADVANCED_BIGINT_ALGORITHMS
}
void TestFFT(int* count) {
#if V8_ADVANCED_BIGINT_ALGORITHMS
// Larger multiplications are slower, so to keep individual runs fast,
// we test a few random samples. With build bots running 24/7, we'll
// get decent coverage over time.
uint64_t random_bits = rng_.NextUint64();
int min = kFftThreshold - static_cast<int>(random_bits & 1023);
random_bits >>= 10;
int max = kFftThreshold + static_cast<int>(random_bits & 1023);
random_bits >>= 10;
// If delta is too small, then this run gets too slow. If it happened
// to be zero, we'd even loop forever!
int delta = 10 + (random_bits & 127);
std::cout << "min " << min << " max " << max << " delta " << delta << "\n";
for (int right_size = min; right_size <= max; right_size += delta) {
for (int left_size = right_size; left_size <= max; left_size += delta) {
ScratchDigits A(left_size);
ScratchDigits B(right_size);
int result_len = MultiplyResultLength(A, B);
ScratchDigits result(result_len);
ScratchDigits result_toom(result_len);
GenerateRandom(A);
GenerateRandom(B);
processor()->MultiplyFFT(result, A, B);
// Using Toom-Cook as reference.
processor()->MultiplyToomCook(result_toom, A, B);
AssertEquals(A, B, result_toom, result);
if (error_) return;
(*count)++;
}
}
#endif // V8_ADVANCED_BIGINT_ALGORITHMS
}
void TestBurnikel(int* count) {
// Start small to save test execution time.
constexpr int kMin = kBurnikelThreshold / 2;
constexpr int kMax = 2 * kBurnikelThreshold;
for (int right_size = kMin; right_size <= kMax; right_size++) {
for (int left_size = right_size; left_size <= kMax; left_size++) {
ScratchDigits A(left_size);
ScratchDigits B(right_size);
GenerateRandom(A);
GenerateRandom(B);
int quotient_len = DivideResultLength(A, B);
int remainder_len = right_size;
ScratchDigits quotient(quotient_len);
ScratchDigits quotient_schoolbook(quotient_len);
ScratchDigits remainder(remainder_len);
ScratchDigits remainder_schoolbook(remainder_len);
processor()->DivideBurnikelZiegler(quotient, remainder, A, B);
processor()->DivideSchoolbook(quotient_schoolbook, remainder_schoolbook,
A, B);
AssertEquals(A, B, quotient_schoolbook, quotient);
AssertEquals(A, B, remainder_schoolbook, remainder);
if (error_) return;
(*count)++;
}
}
}
#if V8_ADVANCED_BIGINT_ALGORITHMS
void TestBarrett_Internal(int left_size, int right_size) {
ScratchDigits A(left_size);
ScratchDigits B(right_size);
GenerateRandom(A);
GenerateRandom(B);
int quotient_len = DivideResultLength(A, B);
// {DivideResultLength} doesn't expect to be called for sizes below
// {kBarrettThreshold} (which we do here to save time), so we have to
// manually adjust the allocated result length.
if (B.len() < kBarrettThreshold) quotient_len++;
int remainder_len = right_size;
ScratchDigits quotient(quotient_len);
ScratchDigits quotient_burnikel(quotient_len);
ScratchDigits remainder(remainder_len);
ScratchDigits remainder_burnikel(remainder_len);
processor()->DivideBarrett(quotient, remainder, A, B);
processor()->DivideBurnikelZiegler(quotient_burnikel, remainder_burnikel, A,
B);
AssertEquals(A, B, quotient_burnikel, quotient);
AssertEquals(A, B, remainder_burnikel, remainder);
}
void TestBarrett(int* count) {
// We pick a range around kBurnikelThreshold (instead of kBarrettThreshold)
// to save test execution time.
constexpr int kMin = kBurnikelThreshold / 2;
constexpr int kMax = 2 * kBurnikelThreshold;
// {DivideBarrett(A, B)} requires that A.len > B.len!
for (int right_size = kMin; right_size <= kMax; right_size++) {
for (int left_size = right_size + 1; left_size <= kMax; left_size++) {
TestBarrett_Internal(left_size, right_size);
if (error_) return;
(*count)++;
}
}
// We also test one random large case.
uint64_t random_bits = rng_.NextUint64();
int right_size = kBarrettThreshold + static_cast<int>(random_bits & 0x3FF);
random_bits >>= 10;
int left_size = right_size + 1 + static_cast<int>(random_bits & 0x3FFF);
random_bits >>= 14;
TestBarrett_Internal(left_size, right_size);
if (error_) return;
(*count)++;
}
#else
void TestBarrett(int* count) {}
#endif // V8_ADVANCED_BIGINT_ALGORITHMS
void TestToString(int* count) {
constexpr int kMin = kToStringFastThreshold / 2;
constexpr int kMax = kToStringFastThreshold * 2;
for (int size = kMin; size < kMax; size++) {
ScratchDigits X(size);
GenerateRandom(X);
for (int radix = 2; radix <= 36; radix++) {
int chars_required = ToStringResultLength(X, radix, false);
int result_len = chars_required;
int reference_len = chars_required;
std::unique_ptr<char[]> result(new char[result_len]);
std::unique_ptr<char[]> reference(new char[reference_len]);
processor()->ToStringImpl(result.get(), &result_len, X, radix, false,
true);
processor()->ToStringImpl(reference.get(), &reference_len, X, radix,
false, false);
AssertEquals(X, radix, reference.get(), reference_len, result.get(),
result_len);
if (error_) return;
(*count)++;
}
}
}
void TestFromString(int* count) {
constexpr int kMaxDigits = 1 << 20; // Any large-enough value will do.
constexpr int kMin = kFromStringLargeThreshold / 2;
constexpr int kMax = kFromStringLargeThreshold * 2;
for (int size = kMin; size < kMax; size++) {
// To keep test execution times low, test one random radix every time.
// Generally, radixes 2 through 36 (inclusive) are supported; however
// the functions {FromStringLarge} and {FromStringClassic} can't deal
// with the data format that {Parse} creates for power-of-two radixes,
// so we skip power-of-two radixes here (and test them separately below).
// We round up the number of radixes in the list to 32 by padding with
// 10, giving decimal numbers extra test coverage, and making it easy
// to evenly map a random number into the index space.
constexpr uint8_t radixes[] = {3, 5, 6, 7, 9, 10, 11, 12, 13, 14, 15,
17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27,
28, 29, 30, 31, 33, 34, 35, 36, 10, 10};
int radix_index = (rng_.NextUint64() & 31);
int radix = radixes[radix_index];
int num_chars = std::round(size * kDigitBits / std::log2(radix));
std::unique_ptr<char[]> chars(new char[num_chars]);
GenerateRandomString(chars.get(), num_chars, radix);
FromStringAccumulator accumulator(kMaxDigits);
FromStringAccumulator ref_accumulator(kMaxDigits);
const char* start = chars.get();
const char* end = chars.get() + num_chars;
accumulator.Parse(start, end, radix);
ref_accumulator.Parse(start, end, radix);
ScratchDigits result(accumulator.ResultLength());
ScratchDigits reference(ref_accumulator.ResultLength());
processor()->FromStringLarge(result, &accumulator);
processor()->FromStringClassic(reference, &ref_accumulator);
AssertEquals(start, num_chars, radix, result, reference);
if (error_) return;
(*count)++;
}
}
void TestFromStringBaseTwo(int* count) {
constexpr int kMaxDigits = 1 << 20; // Any large-enough value will do.
constexpr int kMin = 1;
constexpr int kMax = 100;
for (int size = kMin; size < kMax; size++) {
ScratchDigits X(size);
GenerateRandom(X);
for (int bits = 1; bits <= 5; bits++) {
int radix = 1 << bits;
int chars_required = ToStringResultLength(X, radix, false);
int string_len = chars_required;
std::unique_ptr<char[]> chars(new char[string_len]);
processor()->ToStringImpl(chars.get(), &string_len, X, radix, false,
true);
// Fill any remaining allocated characters with garbage to test that
// too.
for (int i = string_len; i < chars_required; i++) {
chars[i] = '?';
}
const char* start = chars.get();
const char* end = start + chars_required;
FromStringAccumulator accumulator(kMaxDigits);
accumulator.Parse(start, end, radix);
ScratchDigits result(accumulator.ResultLength());
processor()->FromString(result, &accumulator);
AssertEquals(start, chars_required, radix, X, result);
if (error_) return;
(*count)++;
}
}
}
int ParseOptions(int argc, char** argv) {
for (int i = 1; i < argc; i++) {
if (strcmp(argv[i], "--list") == 0) {
op_ = kList;
} else if (strcmp(argv[i], "--help") == 0 || strcmp(argv[i], "-h") == 0) {
PrintHelp(argv);
return 0;
} else if (strcmp(argv[i], "--random-seed") == 0 ||
strcmp(argv[i], "--random_seed") == 0) {
random_seed_ = std::stoi(argv[++i]);
} else if (strncmp(argv[i], "--random-seed=", 14) == 0 ||
strncmp(argv[i], "--random_seed=", 14) == 0) {
random_seed_ = std::stoi(argv[i] + 14);
} else if (strcmp(argv[i], "--runs") == 0) {
runs_ = std::stoi(argv[++i]);
} else if (strncmp(argv[i], "--runs=", 7) == 0) {
runs_ = std::stoi(argv[i] + 7);
}
#define TEST(kName, name) \
else if (strcmp(argv[i], name) == 0) { \
op_ = kTest; \
test_ = kName; \
}
TESTS(TEST)
#undef TEST
else {
std::cerr << "Warning: ignored argument: " << argv[i] << "\n";
}
}
if (op_ == kNoOp) return PrintHelp(argv); // op is mandatory.
return 0;
}
private:
void GenerateRandom(RWDigits Z) {
if (Z.len() == 0) return;
int mode = static_cast<int>(rng_.NextUint64() & 3);
if (mode == 0) {
// Generate random bits.
if (sizeof(digit_t) == 8) {
for (int i = 0; i < Z.len(); i++) {
Z[i] = static_cast<digit_t>(rng_.NextUint64());
}
} else {
for (int i = 0; i < Z.len(); i += 2) {
uint64_t random = rng_.NextUint64();
Z[i] = static_cast<digit_t>(random);
if (i + 1 < Z.len()) Z[i + 1] = static_cast<digit_t>(random >> 32);
}
}
// Special case: we don't want the MSD to be zero.
while (Z.msd() == 0) {
Z[Z.len() - 1] = static_cast<digit_t>(rng_.NextUint64());
}
return;
}
if (mode == 1) {
// Generate a power of 2, with the lone 1-bit somewhere in the MSD.
int bit_in_msd = static_cast<int>(rng_.NextUint64() % kDigitBits);
Z[Z.len() - 1] = digit_t{1} << bit_in_msd;
for (int i = 0; i < Z.len() - 1; i++) Z[i] = 0;
return;
}
// For mode == 2 and mode == 3, generate a random number of 1-bits in the
// MSD, aligned to the least-significant end.
int bits_in_msd = static_cast<int>(rng_.NextUint64() % kDigitBits);
digit_t msd = (digit_t{1} << bits_in_msd) - 1;
if (msd == 0) msd = ~digit_t{0};
Z[Z.len() - 1] = msd;
if (mode == 2) {
// The non-MSD digits are all 1-bits.
for (int i = 0; i < Z.len() - 1; i++) Z[i] = ~digit_t{0};
} else {
// mode == 3
// Each non-MSD digit is either all ones or all zeros.
uint64_t random;
int random_bits = 0;
for (int i = 0; i < Z.len() - 1; i++) {
if (random_bits == 0) {
random = rng_.NextUint64();
random_bits = 64;
}
Z[i] = random & 1 ? ~digit_t{0} : digit_t{0};
random >>= 1;
random_bits--;
}
}
}
void GenerateRandomString(char* str, int len, int radix) {
DCHECK(2 <= radix && radix <= 36);
if (len == 0) return;
uint64_t random;
int available_bits = 0;
const int char_bits = BitLength(radix - 1);
const uint64_t char_mask = (1u << char_bits) - 1u;
for (int i = 0; i < len; i++) {
while (true) {
if (available_bits < char_bits) {
random = rng_.NextUint64();
available_bits = 64;
}
int next_char = static_cast<int>(random & char_mask);
random = random >> char_bits;
available_bits -= char_bits;
if (next_char >= radix) continue;
*str = kConversionChars[next_char];
str++;
break;
};
}
}
Operation op_{kNoOp};
Test test_;
bool error_{false};
int runs_ = 1;
int64_t random_seed_{314159265359};
RNG rng_;
std::unique_ptr<Processor, Processor::Destroyer> processor_;
};
} // namespace test
} // namespace bigint
} // namespace v8
int main(int argc, char** argv) {
v8::bigint::test::Runner runner;
int ret = runner.ParseOptions(argc, argv);
if (ret != 0) return ret;
runner.Initialize();
return runner.Run();
}
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