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// 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.
#include "src/tint/fuzzers/tint_regex_fuzzer/wgsl_mutator.h"
#include <cassert>
#include <cstring>
#include <map>
#include <regex>
#include <string>
#include <unordered_set>
#include <utility>
#include <vector>
#include "src/tint/fuzzers/random_generator.h"
namespace tint::fuzzers::regex_fuzzer {
WgslMutator::WgslMutator(RandomGenerator& generator) : generator_(generator) {}
std::vector<size_t> WgslMutator::FindDelimiterIndices(const std::string& delimiter,
const std::string& wgsl_code) {
std::vector<size_t> result;
for (size_t pos = wgsl_code.find(delimiter, 0); pos != std::string::npos;
pos = wgsl_code.find(delimiter, pos + 1)) {
result.push_back(pos);
}
return result;
}
std::unordered_set<std::string> WgslMutator::GetCommonKeywords() {
return {"array", "bool", "break", "compute", "continue", "f32", "fn", "fragment",
"i32", "if", "for", "let", "location", "loop", "ptr", "return",
"struct", "u32", "var", "vec2", "vec3", "vec4", "vertex", "while"};
}
std::vector<std::pair<size_t, size_t>> WgslMutator::GetIdentifiers(const std::string& wgsl_code) {
std::vector<std::pair<size_t, size_t>> result;
// To reduce the rate that invalid programs are produced, common keywords will be excluded from
// the identifiers that are returned.
std::unordered_set<std::string> common_keywords = GetCommonKeywords();
// This regular expression works by looking for a character that
// is not part of an identifier followed by a WGSL identifier, followed
// by a character which cannot be part of a WGSL identifer. The regex
// for the WGSL identifier is obtained from:
// https://www.w3.org/TR/WGSL/#identifiers.
std::regex identifier_regex("[_a-zA-Z][0-9a-zA-Z_]*");
auto identifiers_begin =
std::sregex_iterator(wgsl_code.begin(), wgsl_code.end(), identifier_regex);
auto identifiers_end = std::sregex_iterator();
for (std::sregex_iterator i = identifiers_begin; i != identifiers_end; ++i) {
if (common_keywords.count(i->str()) > 0) {
// This is a common keyword, so skip it.
continue;
}
result.push_back(
{static_cast<size_t>(i->prefix().second - wgsl_code.cbegin()), i->str().size()});
}
return result;
}
std::vector<std::pair<size_t, size_t>> WgslMutator::GetFunctionCallIdentifiers(
const std::string& wgsl_code) {
std::vector<std::pair<size_t, size_t>> result;
std::regex call_regex("([_a-zA-Z][0-9a-zA-Z_]*)[ \\n]*\\(");
auto identifiers_begin = std::sregex_iterator(wgsl_code.begin(), wgsl_code.end(), call_regex);
auto identifiers_end = std::sregex_iterator();
for (std::sregex_iterator i = identifiers_begin; i != identifiers_end; ++i) {
auto submatch = (*i)[1];
result.push_back(
{static_cast<size_t>(submatch.first - wgsl_code.cbegin()), submatch.str().size()});
}
return result;
}
std::vector<std::pair<size_t, size_t>> WgslMutator::GetIntLiterals(const std::string& s) {
std::vector<std::pair<size_t, size_t>> result;
// Looks for integer literals in decimal or hexadecimal form.
// Regex obtained here: https://www.w3.org/TR/WGSL/#literals
std::regex int_literal_regex("-?0x[0-9a-fA-F]+ | 0 | -?[1-9][0-9]*");
std::regex uint_literal_regex("0x[0-9a-fA-F]+u | 0u | [1-9][0-9]*u");
std::smatch match;
std::string::const_iterator search_start(s.cbegin());
std::string prefix = "";
while (regex_search(search_start, s.cend(), match, int_literal_regex) ||
regex_search(search_start, s.cend(), match, uint_literal_regex)) {
prefix += match.prefix();
result.push_back(std::make_pair(prefix.size() + 1, match.str(0).size() - 1));
prefix += match.str(0);
search_start = match.suffix().first;
}
return result;
}
size_t WgslMutator::FindClosingBracket(size_t opening_bracket_pos,
const std::string& wgsl_code,
char opening_bracket_character,
char closing_bracket_character) {
size_t open_bracket_count = 1;
size_t pos = opening_bracket_pos + 1;
while (open_bracket_count >= 1 && pos < wgsl_code.size()) {
if (wgsl_code[pos] == opening_bracket_character) {
++open_bracket_count;
} else if (wgsl_code[pos] == closing_bracket_character) {
--open_bracket_count;
}
++pos;
}
return (pos == wgsl_code.size() && open_bracket_count >= 1) ? 0 : pos - 1;
}
std::vector<std::pair<size_t, bool>> WgslMutator::GetFunctionBodyPositions(
const std::string& wgsl_code) {
// Finds all the functions with a non-void return value.
std::regex function_regex("fn[^a-zA-Z_0-9][^\\{]*\\{");
std::vector<std::pair<size_t, bool>> result;
auto functions_begin = std::sregex_iterator(wgsl_code.begin(), wgsl_code.end(), function_regex);
auto functions_end = std::sregex_iterator();
for (std::sregex_iterator i = functions_begin; i != functions_end; ++i) {
bool returns_value = i->str().find("->") != std::string::npos;
result.push_back(
{static_cast<size_t>(i->suffix().first - wgsl_code.cbegin() - 1), returns_value});
}
return result;
}
std::vector<size_t> WgslMutator::GetLoopBodyPositions(const std::string& wgsl_code) {
// Finds all loops.
std::regex loop_regex("[^a-zA-Z_0-9](for|while|loop)[^\\{]*\\{");
std::vector<size_t> result;
auto loops_begin = std::sregex_iterator(wgsl_code.begin(), wgsl_code.end(), loop_regex);
auto loops_end = std::sregex_iterator();
for (std::sregex_iterator i = loops_begin; i != loops_end; ++i) {
result.push_back(static_cast<size_t>(i->suffix().first - wgsl_code.cbegin() - 1));
}
return result;
}
bool WgslMutator::InsertReturnStatement(std::string& wgsl_code) {
std::vector<std::pair<size_t, bool>> function_body_positions =
GetFunctionBodyPositions(wgsl_code);
// No function was found in wgsl_code.
if (function_body_positions.empty()) {
return false;
}
// Pick a random function
auto function = generator_.GetRandomElement(function_body_positions);
// Find the corresponding closing bracket for the function, and find a semi-colon within the
// function body.
size_t left_bracket_pos = function.first;
size_t right_bracket_pos = FindClosingBracket(left_bracket_pos, wgsl_code, '{', '}');
if (right_bracket_pos == 0) {
return false;
}
std::vector<size_t> semicolon_positions;
for (size_t pos = wgsl_code.find(";", left_bracket_pos + 1); pos < right_bracket_pos;
pos = wgsl_code.find(";", pos + 1)) {
semicolon_positions.push_back(pos);
}
if (semicolon_positions.empty()) {
return false;
}
std::string return_statement = "return";
if (function.second) {
// The function returns a value. Get all identifiers and integer literals to use as
// potential return values.
std::vector<std::pair<size_t, size_t>> identifiers = GetIdentifiers(wgsl_code);
auto return_values = identifiers;
std::vector<std::pair<size_t, size_t>> int_literals = GetIntLiterals(wgsl_code);
return_values.insert(return_values.end(), int_literals.begin(), int_literals.end());
std::pair<size_t, size_t> return_value = generator_.GetRandomElement(return_values);
return_statement += " " + wgsl_code.substr(return_value.first, return_value.second);
}
return_statement += ";";
// Insert the return statement immediately after the semicolon.
wgsl_code.insert(generator_.GetRandomElement(semicolon_positions) + 1, return_statement);
return true;
}
bool WgslMutator::InsertBreakOrContinue(std::string& wgsl_code) {
std::vector<size_t> loop_body_positions = GetLoopBodyPositions(wgsl_code);
// No loop was found in wgsl_code.
if (loop_body_positions.empty()) {
return false;
}
// Pick a random loop's opening bracket, find the corresponding closing
// bracket, and find a semi-colon within the loop body.
size_t left_bracket_pos = generator_.GetRandomElement(loop_body_positions);
size_t right_bracket_pos = FindClosingBracket(left_bracket_pos, wgsl_code, '{', '}');
if (right_bracket_pos == 0) {
return false;
}
std::vector<size_t> semicolon_positions;
for (size_t pos = wgsl_code.find(";", left_bracket_pos + 1); pos < right_bracket_pos;
pos = wgsl_code.find(";", pos + 1)) {
semicolon_positions.push_back(pos);
}
if (semicolon_positions.empty()) {
return false;
}
size_t semicolon_position = generator_.GetRandomElement(semicolon_positions);
// Insert a break or continue immediately after the semicolon.
wgsl_code.insert(semicolon_position + 1, generator_.GetBool() ? "break;" : "continue;");
return true;
}
void WgslMutator::SwapIntervals(size_t idx1,
size_t reg1_len,
size_t idx2,
size_t reg2_len,
std::string& wgsl_code) {
std::string region_1 = wgsl_code.substr(idx1 + 1, reg1_len - 1);
std::string region_2 = wgsl_code.substr(idx2 + 1, reg2_len - 1);
// The second transformation is done first as it doesn't affect idx2.
wgsl_code.replace(idx2 + 1, region_2.size(), region_1);
wgsl_code.replace(idx1 + 1, region_1.size(), region_2);
}
void WgslMutator::DeleteInterval(size_t idx1, size_t reg_len, std::string& wgsl_code) {
wgsl_code.erase(idx1 + 1, reg_len - 1);
}
void WgslMutator::DuplicateInterval(size_t idx1,
size_t reg1_len,
size_t idx2,
std::string& wgsl_code) {
std::string region = wgsl_code.substr(idx1 + 1, reg1_len - 1);
wgsl_code.insert(idx2 + 1, region);
}
void WgslMutator::ReplaceRegion(size_t idx1,
size_t id1_len,
size_t idx2,
size_t id2_len,
std::string& wgsl_code) {
std::string region_1 = wgsl_code.substr(idx1, id1_len);
std::string region_2 = wgsl_code.substr(idx2, id2_len);
wgsl_code.replace(idx2, region_2.size(), region_1);
}
void WgslMutator::ReplaceInterval(size_t start_index,
size_t length,
std::string replacement_text,
std::string& wgsl_code) {
std::string region_1 = wgsl_code.substr(start_index, length);
wgsl_code.replace(start_index, length, replacement_text);
}
bool WgslMutator::SwapRandomIntervals(const std::string& delimiter, std::string& wgsl_code) {
std::vector<size_t> delimiter_positions = FindDelimiterIndices(delimiter, wgsl_code);
// Need to have at least 3 indices.
if (delimiter_positions.size() < 3) {
return false;
}
// Choose indices:
// interval_1_start < interval_1_end <= interval_2_start < interval_2_end
uint32_t interval_1_start =
generator_.GetUInt32(static_cast<uint32_t>(delimiter_positions.size()) - 2u);
uint32_t interval_1_end = generator_.GetUInt32(
interval_1_start + 1u, static_cast<uint32_t>(delimiter_positions.size()) - 1u);
uint32_t interval_2_start = generator_.GetUInt32(
interval_1_end, static_cast<uint32_t>(delimiter_positions.size()) - 1u);
uint32_t interval_2_end = generator_.GetUInt32(
interval_2_start + 1u, static_cast<uint32_t>(delimiter_positions.size()));
SwapIntervals(delimiter_positions[interval_1_start],
delimiter_positions[interval_1_end] - delimiter_positions[interval_1_start],
delimiter_positions[interval_2_start],
delimiter_positions[interval_2_end] - delimiter_positions[interval_2_start],
wgsl_code);
return true;
}
bool WgslMutator::DeleteRandomInterval(const std::string& delimiter, std::string& wgsl_code) {
std::vector<size_t> delimiter_positions = FindDelimiterIndices(delimiter, wgsl_code);
// Need to have at least 2 indices.
if (delimiter_positions.size() < 2) {
return false;
}
uint32_t interval_start =
generator_.GetUInt32(static_cast<uint32_t>(delimiter_positions.size()) - 1u);
uint32_t interval_end = generator_.GetUInt32(interval_start + 1u,
static_cast<uint32_t>(delimiter_positions.size()));
DeleteInterval(delimiter_positions[interval_start],
delimiter_positions[interval_end] - delimiter_positions[interval_start],
wgsl_code);
return true;
}
bool WgslMutator::DuplicateRandomInterval(const std::string& delimiter, std::string& wgsl_code) {
std::vector<size_t> delimiter_positions = FindDelimiterIndices(delimiter, wgsl_code);
// Need to have at least 2 indices
if (delimiter_positions.size() < 2) {
return false;
}
uint32_t interval_start =
generator_.GetUInt32(static_cast<uint32_t>(delimiter_positions.size()) - 1u);
uint32_t interval_end = generator_.GetUInt32(interval_start + 1u,
static_cast<uint32_t>(delimiter_positions.size()));
uint32_t duplication_point =
generator_.GetUInt32(static_cast<uint32_t>(delimiter_positions.size()));
DuplicateInterval(delimiter_positions[interval_start],
delimiter_positions[interval_end] - delimiter_positions[interval_start],
delimiter_positions[duplication_point], wgsl_code);
return true;
}
bool WgslMutator::ReplaceRandomIdentifier(std::string& wgsl_code) {
std::vector<std::pair<size_t, size_t>> identifiers = GetIdentifiers(wgsl_code);
// Need at least 2 identifiers
if (identifiers.size() < 2) {
return false;
}
uint32_t id1_index = generator_.GetUInt32(static_cast<uint32_t>(identifiers.size()));
uint32_t id2_index = generator_.GetUInt32(static_cast<uint32_t>(identifiers.size()));
// The two identifiers must be different
while (id1_index == id2_index) {
id2_index = generator_.GetUInt32(static_cast<uint32_t>(identifiers.size()));
}
ReplaceRegion(identifiers[id1_index].first, identifiers[id1_index].second,
identifiers[id2_index].first, identifiers[id2_index].second, wgsl_code);
return true;
}
bool WgslMutator::ReplaceRandomIntLiteral(std::string& wgsl_code) {
std::vector<std::pair<size_t, size_t>> literals = GetIntLiterals(wgsl_code);
// Need at least one integer literal
if (literals.size() < 1) {
return false;
}
uint32_t literal_index = generator_.GetUInt32(static_cast<uint32_t>(literals.size()));
// INT_MAX = 2147483647, INT_MIN = -2147483648
std::vector<std::string> boundary_values = {"2147483647", "-2147483648", "1",
"-1", "0", "4294967295"};
uint32_t boundary_index = generator_.GetUInt32(static_cast<uint32_t>(boundary_values.size()));
ReplaceInterval(literals[literal_index].first, literals[literal_index].second,
boundary_values[boundary_index], wgsl_code);
return true;
}
std::string WgslMutator::ChooseRandomReplacementForOperator(const std::string& existing_operator) {
// Operators are partitioned into three classes: assignment, expression and increment. The regex
// mutator will swap operators in the same class. The hypothesis is that this should exercise a
// number of type-safe swaps (e.g. changing += to *=), as well as some badly-typed yet
// interesting swaps (e.g. changing + to ^ when the operators are matrices), while avoiding
// making totally nonsensical replacements (such as changing ++ too /).
std::vector<std::string> assignment_operators{
"=", "+=", "-=", "*=", "/=", "%=", "&=", "|=", "^=", "<<=", ">>="};
std::vector<std::string> expression_operators{"+", "-", "*", "/", "%", "&&", "||",
"&", "|", "^", "<<", ">>", "<", ">",
"<=", ">=", "!", "!=", "~"};
std::vector<std::string> increment_operators{"++", "--"};
for (auto operators : {assignment_operators, expression_operators, increment_operators}) {
auto it = std::find(operators.begin(), operators.end(), existing_operator);
if (it != operators.end()) {
// The operator falls into this category, so select another operator from the category.
operators.erase(it);
return generator_.GetRandomElement(operators);
}
}
assert(false && "Unknown operator");
return "";
}
bool WgslMutator::ReplaceRandomOperator(std::string& wgsl_code) {
// Choose an index into the code at random.
const uint32_t start_index = generator_.GetUInt32(static_cast<uint32_t>(wgsl_code.size()));
// Find the first operator occurrence from the chosen point, wrapping back to the start of the
// file if needed.
auto maybe_operator_occurrence = FindOperatorOccurrence(wgsl_code, start_index);
if (!maybe_operator_occurrence.has_value()) {
// It is unlikely that there will be *no* operators in the file, but if this is the case
// then this mutation cannot be applied.
return false;
}
std::string existing_operator =
wgsl_code.substr(maybe_operator_occurrence->first, maybe_operator_occurrence->second);
// Replace the identified operator with a randomly-chosen alternative.
wgsl_code.replace(maybe_operator_occurrence->first, maybe_operator_occurrence->second,
ChooseRandomReplacementForOperator(existing_operator));
return true;
}
std::optional<std::pair<uint32_t, uint32_t>> WgslMutator::FindOperatorOccurrence(
const std::string& wgsl_code,
uint32_t start_index) {
// Loops through the characters of the code in a wrap-around fashion, looking for the first
// encountered token that is a WGSL operator.
for (size_t i = 0; i < wgsl_code.size(); i++) {
uint32_t current_index = static_cast<uint32_t>((start_index + i) % wgsl_code.size());
// To cater for multi-character operator tokens, get the three consecutive characters from
// the code string starting at the current index. Use null characters to account for the
// case where search has reached the end of the code string.
char first_character = wgsl_code[current_index];
char second_character =
current_index == wgsl_code.size() - 1 ? '\0' : wgsl_code[current_index + 1];
char third_character =
current_index >= wgsl_code.size() - 2 ? '\0' : wgsl_code[current_index + 2];
// This uses the extracted characters to match for the various WGSL operators.
switch (first_character) {
case '!':
case '^':
switch (second_character) {
case '=':
return {{current_index, 2}};
default:
return {{current_index, 1}};
}
case '|':
case '&':
case '+':
case '-':
if (second_character == first_character || second_character == '=') {
return {{current_index, 2}};
}
return {{current_index, 1}};
case '*':
case '/':
case '%':
switch (second_character) {
case '=':
return {{current_index, 2}};
default:
return {{current_index, 1}};
}
case '=':
if (second_character == '=') {
return {{current_index, 2}};
}
return {{current_index, 1}};
case '<':
case '>':
if (second_character == '=') {
return {{current_index, 2}};
}
if (second_character == first_character) {
if (third_character == '=') {
return {{current_index, 3}};
}
return {{current_index, 2}};
}
return {{current_index, 1}};
case '~':
return {{current_index, 1}};
default:
break;
}
}
// No operator was found, so empty is returned.
return {};
}
bool WgslMutator::ReplaceFunctionCallWithBuiltin(std::string& wgsl_code) {
std::vector<std::pair<size_t, bool>> function_body_positions =
GetFunctionBodyPositions(wgsl_code);
// No function was found in wgsl_code.
if (function_body_positions.empty()) {
return false;
}
// Pick a random function
auto function = generator_.GetRandomElement(function_body_positions);
// Find the corresponding closing bracket for the function.
size_t left_bracket_pos = function.first;
size_t right_bracket_pos = FindClosingBracket(left_bracket_pos, wgsl_code, '{', '}');
if (right_bracket_pos == 0) {
return false;
}
std::string function_body(
wgsl_code.substr(left_bracket_pos, right_bracket_pos - left_bracket_pos));
std::vector<std::pair<size_t, size_t>> function_call_identifiers =
GetFunctionCallIdentifiers(function_body);
if (function_call_identifiers.empty()) {
return false;
}
auto function_call_identifier = generator_.GetRandomElement(function_call_identifiers);
std::vector<std::string> builtin_functions{"all",
"any",
"select",
"arrayLength",
"abs",
"acos",
"acosh",
"asin",
"asinh",
"atan",
"atanh",
"atan2",
"ceil",
"clamp",
"cos",
"cosh",
"cross",
"degrees",
"distance",
"exp",
"exp2",
"faceForward",
"floor",
"fma",
"fract",
"frexp",
"inverseSqrt",
"ldexp",
"length",
"log",
"log2",
"max",
"min",
"mix",
"modf",
"normalize",
"pow",
"quantizeToF16",
"radians",
"reflect",
"refract",
"round",
"saturate",
"sign",
"sin",
"sinh",
"smoothstep",
"sqrt",
"step",
"tan",
"tanh",
"trunc",
"abs",
"clamp",
"countLeadingZeros",
"countOneBits",
"countTrailingZeros",
"extractBits",
"firstLeadingBit",
"firstTrailingBit",
"insertBits",
"max",
"min",
"reverseBits",
"determinant",
"transpose",
"dot",
"dpdx",
"dpdxCoarse",
"dpdxFine",
"dpdy",
"dpdyCoarse",
"dpdyFine",
"fwidth",
"fwidthCoarse",
"fwidthFine",
"textureDimensions",
"textureGather",
"textureGatherCompare",
"textureLoad",
"textureNumLayers",
"textureNumLevels",
"textureNumSamples",
"textureSample",
"textureSampleBias",
"textureSampleCompare",
"textureSampleCompareLevel",
"textureSampleGrad",
"textureSampleLevel",
"textureStore",
"atomicLoad",
"atomicStore",
"atomicAdd",
"atomicSub",
"atomicMax",
"atomicMin",
"atomicAnd",
"atomicOr",
"atomicXor",
"pack4x8snorm",
"pack4x8unorm",
"pack2x16snorm",
"pack2x16unorm",
"pack2x16float",
"unpack4x8snorm",
"unpack4x8unorm",
"unpack2x16snorm",
"unpack2x16unorm",
"unpack2x16float",
"storageBarrier",
"workgroupBarrier"};
wgsl_code.replace(left_bracket_pos + function_call_identifier.first,
function_call_identifier.second,
generator_.GetRandomElement(builtin_functions));
return true;
}
bool WgslMutator::AddSwizzle(std::string& wgsl_code) {
std::vector<std::pair<size_t, bool>> function_body_positions =
GetFunctionBodyPositions(wgsl_code);
// No function was found in wgsl_code.
if (function_body_positions.empty()) {
return false;
}
// Pick a random function
auto function = generator_.GetRandomElement(function_body_positions);
// Find the corresponding closing bracket for the function.
size_t left_bracket_pos = function.first;
size_t right_bracket_pos = FindClosingBracket(left_bracket_pos, wgsl_code, '{', '}');
if (right_bracket_pos == 0) {
return false;
}
std::string function_body(
wgsl_code.substr(left_bracket_pos, right_bracket_pos - left_bracket_pos));
// It makes sense to try applying swizzles to:
// - identifiers, because they might be vectors
auto identifiers = GetIdentifiers(function_body);
// - existing swizzles, e.g. to turn v.xy into v.xy.xx
auto swizzles = GetSwizzles(function_body);
// - vector constructors, e.g. to turn vec3<f32>(...) into vec3<f32>(...).yyz
auto vector_constructors = GetVectorConstructors(function_body);
// Create a combined vector of all the possibilities for swizzling, so that they can be sampled
// from as a whole.
std::vector<std::pair<size_t, size_t>> combined;
combined.insert(combined.end(), identifiers.begin(), identifiers.end());
combined.insert(combined.end(), swizzles.begin(), swizzles.end());
combined.insert(combined.end(), vector_constructors.begin(), vector_constructors.end());
if (combined.empty()) {
// No opportunities for swizzling: give up.
return false;
}
// Randomly create a swizzle operation. This is done without checking the potential length of
// the target vector. For identifiers this isn't possible without proper context. For existing
// swizzles and vector constructors it would be possible to check the length, but it is anyway
// good to stress-test swizzle validation code paths.
std::string swizzle = ".";
{
// Choose a swizzle length between 1 and 4, inclusive.
uint32_t swizzle_length = generator_.GetUInt32(1, 5);
// Decide whether to use xyzw or rgba as convenience names.
bool use_xyzw = generator_.GetBool();
// Randomly choose a convenience name for each component of the swizzle.
for (uint32_t i = 0; i < swizzle_length; i++) {
switch (generator_.GetUInt32(4)) {
case 0:
swizzle += use_xyzw ? "x" : "r";
break;
case 1:
swizzle += use_xyzw ? "y" : "g";
break;
case 2:
swizzle += use_xyzw ? "z" : "b";
break;
case 3:
swizzle += use_xyzw ? "w" : "a";
break;
default:
assert(false && "Unreachable");
break;
}
}
}
// Choose a random opportunity for swizzling and add the swizzle right after it.
auto target = generator_.GetRandomElement(combined);
wgsl_code.insert(left_bracket_pos + target.first + target.second, swizzle);
return true;
}
std::vector<std::pair<size_t, size_t>> WgslMutator::GetSwizzles(const std::string& wgsl_code) {
std::regex swizzle_regex("\\.(([xyzw]+)|([rgba]+))");
std::vector<std::pair<size_t, size_t>> result;
auto swizzles_begin = std::sregex_iterator(wgsl_code.begin(), wgsl_code.end(), swizzle_regex);
auto swizles_end = std::sregex_iterator();
for (std::sregex_iterator i = swizzles_begin; i != swizles_end; ++i) {
result.push_back(
{static_cast<size_t>(i->prefix().second - wgsl_code.cbegin()), i->str().size()});
}
return result;
}
std::vector<std::pair<size_t, size_t>> WgslMutator::GetVectorConstructors(
const std::string& wgsl_code) {
// This regex recognises the prefixes of vector constructors, which have the form:
// "vecn<type>(", with possible whitespace between tokens.
std::regex vector_constructor_prefix_regex("vec\\d[ \\n]*<[ \\n]*[a-z0-9_]+[ \\n]*>[^\\(]*\\(");
std::vector<std::pair<size_t, size_t>> result;
auto vector_constructor_prefixes_begin =
std::sregex_iterator(wgsl_code.begin(), wgsl_code.end(), vector_constructor_prefix_regex);
auto vector_constructor_prefixes_end = std::sregex_iterator();
// Look through all of the vector constructor prefixes and see whether each one appears to
// correspond to a complete vector construction.
for (std::sregex_iterator i = vector_constructor_prefixes_begin;
i != vector_constructor_prefixes_end; ++i) {
// A prefix is deemed to correspond to a complete vector construction if it is possible to
// find a corresponding closing bracket for the "(" at the end of the prefix.
size_t closing_bracket = FindClosingBracket(
static_cast<size_t>(i->suffix().first - wgsl_code.cbegin()), wgsl_code, '(', ')');
if (closing_bracket != 0) {
// A closing bracket was found, so record the start and size of the entire vector
// constructor.
size_t start = static_cast<size_t>(i->prefix().second - wgsl_code.cbegin());
result.push_back({start, closing_bracket - start + 1});
}
}
return result;
}
} // namespace tint::fuzzers::regex_fuzzer