Remove excess copy from fuzzer random number generation code
Adds limited ability to hash C-style buffers, so that the seed can be
directly calculated on the provided input, instead of converting it to
a vector.
BUG=tint:1161
Change-Id: I1b9b0805665436a3242d5918fb563242b91b0f09
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/63420
Auto-Submit: Ryan Harrison <rharrison@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: Ben Clayton <bclayton@google.com>
diff --git a/fuzzers/random_generator.cc b/fuzzers/random_generator.cc
index 73c594c..93c7f4c 100644
--- a/fuzzers/random_generator.cc
+++ b/fuzzers/random_generator.cc
@@ -38,6 +38,22 @@
return std::uniform_int_distribution<I>(lower, upper - 1)(*engine);
}
+/// Calculate the hash for the contents of a c-style data buffer
+/// This is intentionally not implemented as a generic override of HashCombine
+/// in "src/utils/hash.h", because it conflicts with the vardiac override for
+/// the case where a pointer and an integer are being hashed.
+/// @param data - pointer to buffer to be hashed
+/// @param size - number of elements in buffer
+/// @returns hash of the data in the buffer
+size_t HashBuffer(const uint8_t* data, const size_t size) {
+ size_t hash = 102931;
+ utils::HashCombine(&hash, size);
+ for (size_t i = 0; i < size; i++) {
+ utils::HashCombine(&hash, data[i]);
+ }
+ return hash;
+}
+
} // namespace
RandomGenerator::RandomGenerator(uint64_t seed) : engine_(seed) {}
@@ -107,9 +123,7 @@
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);
+ return HashBuffer(data + hash_begin, hash_size);
}
} // namespace fuzzers
