Add regex fuzzer

A fuzzer that mutates a WGSL code by finding two regions enclosed by
semicolons and swapping them randomly.

Change-Id: I5b14eb21fd2924227d05ac516f806c6e2efa6198
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/58395
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Alastair Donaldson <afdx@google.com>
Reviewed-by: Ryan Harrison <rharrison@chromium.org>
Commit-Queue: Alastair Donaldson <afdx@google.com>

fuzzers/tint_regex_fuzzer/cli.h

@@ -0,0 +1,64 @@
+// Copyright 2021 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef FUZZERS_TINT_REGEX_FUZZER_CLI_H_
+#define FUZZERS_TINT_REGEX_FUZZER_CLI_H_
+
+#include <cstdint>
+
+namespace tint {
+namespace fuzzers {
+namespace regex_fuzzer {
+
+/// The backend this fuzzer will test.
+enum class FuzzingTarget {
+  kNone = 0,
+  kHlsl = 1 << 0,
+  kMsl = 1 << 1,
+  kSpv = 1 << 2,
+  kWgsl = 1 << 3,
+  kAll = kHlsl | kMsl | kSpv | kWgsl
+};
+
+inline FuzzingTarget operator|(FuzzingTarget a, FuzzingTarget b) {
+  return static_cast<FuzzingTarget>(static_cast<int>(a) | static_cast<int>(b));
+}
+
+inline FuzzingTarget operator&(FuzzingTarget a, FuzzingTarget b) {
+  return static_cast<FuzzingTarget>(static_cast<int>(a) & static_cast<int>(b));
+}
+
+/// CLI parameters accepted by the fuzzer. Type -tint_help in the CLI to see the
+/// help message
+struct CliParams {
+  /// Compiler backends we want to fuzz.
+  FuzzingTarget fuzzing_target = FuzzingTarget::kAll;
+};
+
+/// @brief Parses CLI parameters.
+///
+/// This function will exit the process with non-zero return code if some
+/// parameters are invalid. This function will remove recognized parameters from
+/// `argv` and adjust `argc` accordingly.
+///
+/// @param argc - the total number of parameters.
+/// @param argv - array of all CLI parameters.
+/// @return parsed parameters.
+CliParams ParseCliParams(int* argc, char** argv);
+
+}  // namespace regex_fuzzer
+}  // namespace fuzzers
+}  // namespace tint
+
+#endif  // FUZZERS_TINT_REGEX_FUZZER_CLI_H_