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Convert fuzzer to generating configuration data

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This is instead of consuming a portion of the input, so that the seed
corpus of valid shaders can be more effective.

BUG=tint:1098

Change-Id: If3696527c82c23b09edeea6ddd2a0f935e5e1ac7
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/63301
Auto-Submit: Ryan Harrison <rharrison@chromium.org>
Commit-Queue: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
This commit is contained in:
Ryan Harrison
2021-09-22 14:37:46 +00:00
committed by Tint LUCI CQ
parent 28d6763ef8
commit a617d0f0fc
15 changed files with 164 additions and 183 deletions
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37
fuzzers/random_generator.cc
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@@ -18,6 +18,8 @@
#include <cassert>
#include <vector>
#include "src/utils/hash.h"
namespace tint {
namespace fuzzers {
@@ -38,7 +40,7 @@ I RandomUInt(std::mt19937* engine, I lower, I upper) {
} // namespace
RandomGenerator::RandomGenerator(uint32_t seed) : engine_(seed) {}
RandomGenerator::RandomGenerator(uint64_t seed) : engine_(seed) {}
uint32_t RandomGenerator::GetUInt32(uint32_t lower, uint32_t upper) {
return RandomUInt(&engine_, lower, upper);
@@ -66,12 +68,11 @@ uint32_t RandomGenerator::Get4Bytes() {
return std::independent_bits_engine<std::mt19937, 32, uint32_t>(engine_)();
}
std::vector<uint8_t> RandomGenerator::GetNBytes(size_t n) {
std::vector<uint8_t> result(n);
void RandomGenerator::GetNBytes(uint8_t* dest, size_t n) {
assert(dest && "|dest| must not be nullptr");
std::generate(
std::begin(result), std::end(result),
dest, dest + n,
std::independent_bits_engine<std::mt19937, 8, uint8_t>(engine_));
return result;
}
bool RandomGenerator::GetBool() {
@@ -85,5 +86,31 @@ bool RandomGenerator::GetWeightedBool(uint32_t percentage) {
return RandomUInt(&engine_, 0u, kMaxPercentage) < percentage;
}
uint64_t RandomGenerator::CalculateSeed(const uint8_t* data, size_t size) {
assert(data != nullptr && "|data| must be !nullptr");
assert(size > 0 && "|size| must be > 0");
// Number of bytes we want to skip at the start of data for the hash.
// Fewer bytes may be skipped when `size` is small.
// Has lower precedence than kHashDesiredMinBytes.
static const int64_t kHashDesiredLeadingSkipBytes = 5;
// Minimum number of bytes we want to use in the hash.
// Used for short buffers.
static const int64_t kHashDesiredMinBytes = 4;
// Maximum number of bytes we want to use in the hash.
static const int64_t kHashDesiredMaxBytes = 32;
int64_t size_i64 = static_cast<int64_t>(size);
int64_t hash_begin_i64 =
std::min(kHashDesiredLeadingSkipBytes,
std::max<int64_t>(size_i64 - kHashDesiredMinBytes, 0));
int64_t hash_end_i64 =
std::max(hash_begin_i64 + kHashDesiredMaxBytes, size_i64);
size_t hash_begin = static_cast<size_t>(hash_begin_i64);
size_t hash_size = static_cast<size_t>(hash_end_i64) - hash_begin;
std::vector<uint8_t> hash_portion(data + hash_begin,
data + hash_begin + hash_size + 1);
return tint::utils::Hash(hash_portion);
}
} // namespace fuzzers
} // namespace tint