src/tint/fuzzers/tint_ast_fuzzer/mutations/delete_statement.cc - dawn - Git at Google

 // 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_ast_fuzzer/mutations/delete_statement.h"

 #include <algorithm>
 #include <utility>
 #include <vector>

 #include "src/tint/fuzzers/tint_ast_fuzzer/jump_tracker.h"
 #include "src/tint/fuzzers/tint_ast_fuzzer/util.h"
 #include "src/tint/lang/wgsl/ast/block_statement.h"
 #include "src/tint/lang/wgsl/ast/for_loop_statement.h"
 #include "src/tint/lang/wgsl/ast/if_statement.h"
 #include "src/tint/lang/wgsl/ast/loop_statement.h"
 #include "src/tint/lang/wgsl/ast/variable_decl_statement.h"
 #include "src/tint/lang/wgsl/program/program_builder.h"
 #include "src/tint/lang/wgsl/sem/for_loop_statement.h"
 #include "src/tint/lang/wgsl/sem/if_statement.h"
 #include "src/tint/lang/wgsl/sem/loop_statement.h"
 #include "src/tint/lang/wgsl/sem/statement.h"

 namespace tint::fuzzers::ast_fuzzer {

 MutationDeleteStatement::MutationDeleteStatement(protobufs::MutationDeleteStatement message)
     : message_(std::move(message)) {}

 MutationDeleteStatement::MutationDeleteStatement(uint32_t statement_id) {
     message_.set_statement_id(statement_id);
 }

 bool MutationDeleteStatement::IsApplicable(const tint::Program& program,
                                            const NodeIdMap& node_id_map) const {
     auto* statement_node = tint::As<ast::Statement>(node_id_map.GetNode(message_.statement_id()));

     if (!statement_node) {
         // The statement id is invalid or does not refer to a statement.
         return false;
     }

     const auto* statement_sem_node = tint::As<sem::Statement>(program.Sem().Get(statement_node));

     if (!statement_sem_node) {
         // Semantic information for the statement is not available. This
         // information is required in order to perform the deletion.
         return false;
     }

     // Check whether it is OK to delete this statement.
     if (!CanBeDeleted(*statement_node, program, JumpTracker(program))) {
         return false;
     }

     return true;
 }

 void MutationDeleteStatement::Apply(const NodeIdMap& node_id_map,
                                     tint::program::CloneContext& clone_context,
                                     NodeIdMap* /* unused */) const {
     const auto* statement_node =
         tint::As<ast::Statement>(node_id_map.GetNode(message_.statement_id()));
     const auto* statement_sem_node =
         tint::As<sem::Statement>(clone_context.src->Sem().Get(statement_node));
     const auto* sem_parent = statement_sem_node->Parent();

     if (tint::Is<sem::IfStatement>(sem_parent) &&
         tint::As<ast::IfStatement>(sem_parent->Declaration())->else_statement == statement_node) {
         // Remove the "else" part of an if statement.
         clone_context.Replace(statement_node, static_cast<const ast::Statement*>(nullptr));
     } else if (tint::Is<sem::ForLoopStatement>(sem_parent) &&
                tint::As<ast::ForLoopStatement>(sem_parent->Declaration())->initializer ==
                    statement_node) {
         // Remove the initializer of a for loop.
         clone_context.Replace(statement_node, static_cast<const ast::Statement*>(nullptr));
     } else if (tint::Is<sem::ForLoopStatement>(sem_parent) &&
                tint::As<ast::ForLoopStatement>(sem_parent->Declaration())->continuing ==
                    statement_node) {
         // Remove the "continuing" statement of a for loop.
         clone_context.Replace(statement_node, static_cast<const ast::Statement*>(nullptr));
     } else if (tint::Is<sem::LoopContinuingBlockStatement>(statement_sem_node)) {
         // Remove the "continuing" block of a loop.
         clone_context.Replace(statement_node, static_cast<const ast::Statement*>(nullptr));
     } else if (tint::Is<ast::CaseStatement>(statement_node)) {
         // Remove a case statement from its enclosing switch statement.
         const auto& case_statement_list =
             &sem_parent->Declaration()->As<ast::SwitchStatement>()->body;
         assert(std::find(case_statement_list->begin(), case_statement_list->end(),
                          statement_node) != case_statement_list->end() &&
                "Statement not found.");
         clone_context.Remove(*case_statement_list, statement_node);
     } else if (tint::Is<ast::BlockStatement>(statement_node)) {
         // Remove a block statement from the block that encloses it. A special case is required for
         // this, since a sem::Block has itself as its associated sem::Block, so it is necessary to
         // look at the parent to get the enclosing block.
         const auto& statement_list =
             sem_parent->Declaration()->As<ast::BlockStatement>()->statements;
         assert(std::find(statement_list.begin(), statement_list.end(), statement_node) !=
                    statement_list.end() &&
                "Statement not found.");
         clone_context.Remove(statement_list, statement_node);
     } else {
         // Remove a non-block statement from the block that encloses it.
         const auto& statement_list =
             statement_sem_node->Block()->Declaration()->As<ast::BlockStatement>()->statements;
         assert(std::find(statement_list.begin(), statement_list.end(), statement_node) !=
                    statement_list.end() &&
                "Statement not found.");
         clone_context.Remove(statement_list, statement_node);
     }
 }

 protobufs::Mutation MutationDeleteStatement::ToMessage() const {
     protobufs::Mutation mutation;
     *mutation.mutable_delete_statement() = message_;
     return mutation;
 }

 bool MutationDeleteStatement::CanBeDeleted(const ast::Statement& statement_node,
                                            const Program& program,
                                            const JumpTracker& jump_tracker) {
     if (statement_node.Is<ast::VariableDeclStatement>()) {
         // This is conservative. It would be possible to delete variable declarations if they are
         // not used. Further analysis could allow that.
         return false;
     }

     if (jump_tracker.ContainsReturn(statement_node)) {
         // This is conservative. It would be possible to delete a return statement as long as there
         // is still a return on every control flow path.
         return false;
     }

     if (jump_tracker.ContainsBreakForInnermostLoop(statement_node)) {
         // This is conservative. Disallowing the removal of breaks ensures that loops cannot become
         // statically infinite. However, a loop might in practice have multiple breaks, some of
         // which can be removed.
         return false;
     }

     if (auto* case_statement = statement_node.As<ast::CaseStatement>()) {
         // It is not OK to delete the case statement which contains the default selector.
         if (case_statement->ContainsDefault()) {
             return false;
         }
     }

     auto* parent_sem = program.Sem().Get(&statement_node)->Parent();
     if (parent_sem == nullptr) {
         // Semantic information for the parent node is required.
         return false;
     }

     auto* parent_stmt = parent_sem->Declaration();

     // It does not make sense to delete the entire body of a loop or if statement.
     if (auto* for_loop = parent_stmt->As<ast::ForLoopStatement>()) {
         if (for_loop->body == &statement_node) {
             return false;
         }
     }
     if (auto* loop = parent_stmt->As<ast::LoopStatement>()) {
         if (loop->body == &statement_node) {
             return false;
         }
     }
     if (auto* while_loop = parent_stmt->As<ast::WhileStatement>()) {
         if (while_loop->body == &statement_node) {
             return false;
         }
     }
     if (auto* if_statement = parent_stmt->As<ast::IfStatement>()) {
         if (if_statement->body == &statement_node) {
             return false;
         }
     }

     return true;
 }

 }  // namespace tint::fuzzers::ast_fuzzer
	// 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_ast_fuzzer/mutations/delete_statement.h"

	#include <algorithm>
	#include <utility>
	#include <vector>

	#include "src/tint/fuzzers/tint_ast_fuzzer/jump_tracker.h"
	#include "src/tint/fuzzers/tint_ast_fuzzer/util.h"
	#include "src/tint/lang/wgsl/ast/block_statement.h"
	#include "src/tint/lang/wgsl/ast/for_loop_statement.h"
	#include "src/tint/lang/wgsl/ast/if_statement.h"
	#include "src/tint/lang/wgsl/ast/loop_statement.h"
	#include "src/tint/lang/wgsl/ast/variable_decl_statement.h"
	#include "src/tint/lang/wgsl/program/program_builder.h"
	#include "src/tint/lang/wgsl/sem/for_loop_statement.h"
	#include "src/tint/lang/wgsl/sem/if_statement.h"
	#include "src/tint/lang/wgsl/sem/loop_statement.h"
	#include "src/tint/lang/wgsl/sem/statement.h"

	namespace tint::fuzzers::ast_fuzzer {

	MutationDeleteStatement::MutationDeleteStatement(protobufs::MutationDeleteStatement message)
	: message_(std::move(message)) {}

	MutationDeleteStatement::MutationDeleteStatement(uint32_t statement_id) {
	message_.set_statement_id(statement_id);
	}

	bool MutationDeleteStatement::IsApplicable(const tint::Program& program,
	const NodeIdMap& node_id_map) const {
	auto* statement_node = tint::As<ast::Statement>(node_id_map.GetNode(message_.statement_id()));

	if (!statement_node) {
	// The statement id is invalid or does not refer to a statement.
	return false;
	}

	const auto* statement_sem_node = tint::As<sem::Statement>(program.Sem().Get(statement_node));

	if (!statement_sem_node) {
	// Semantic information for the statement is not available. This
	// information is required in order to perform the deletion.
	return false;
	}

	// Check whether it is OK to delete this statement.
	if (!CanBeDeleted(*statement_node, program, JumpTracker(program))) {
	return false;
	}

	return true;
	}

	void MutationDeleteStatement::Apply(const NodeIdMap& node_id_map,
	tint::program::CloneContext& clone_context,
	NodeIdMap* /* unused */) const {
	const auto* statement_node =
	tint::As<ast::Statement>(node_id_map.GetNode(message_.statement_id()));
	const auto* statement_sem_node =
	tint::As<sem::Statement>(clone_context.src->Sem().Get(statement_node));
	const auto* sem_parent = statement_sem_node->Parent();

	if (tint::Is<sem::IfStatement>(sem_parent) &&
	tint::As<ast::IfStatement>(sem_parent->Declaration())->else_statement == statement_node) {
	// Remove the "else" part of an if statement.
	clone_context.Replace(statement_node, static_cast<const ast::Statement*>(nullptr));
	} else if (tint::Is<sem::ForLoopStatement>(sem_parent) &&
	tint::As<ast::ForLoopStatement>(sem_parent->Declaration())->initializer ==
	statement_node) {
	// Remove the initializer of a for loop.
	clone_context.Replace(statement_node, static_cast<const ast::Statement*>(nullptr));
	} else if (tint::Is<sem::ForLoopStatement>(sem_parent) &&
	tint::As<ast::ForLoopStatement>(sem_parent->Declaration())->continuing ==
	statement_node) {
	// Remove the "continuing" statement of a for loop.
	clone_context.Replace(statement_node, static_cast<const ast::Statement*>(nullptr));
	} else if (tint::Is<sem::LoopContinuingBlockStatement>(statement_sem_node)) {
	// Remove the "continuing" block of a loop.
	clone_context.Replace(statement_node, static_cast<const ast::Statement*>(nullptr));
	} else if (tint::Is<ast::CaseStatement>(statement_node)) {
	// Remove a case statement from its enclosing switch statement.
	const auto& case_statement_list =
	&sem_parent->Declaration()->As<ast::SwitchStatement>()->body;
	assert(std::find(case_statement_list->begin(), case_statement_list->end(),
	statement_node) != case_statement_list->end() &&
	"Statement not found.");
	clone_context.Remove(*case_statement_list, statement_node);
	} else if (tint::Is<ast::BlockStatement>(statement_node)) {
	// Remove a block statement from the block that encloses it. A special case is required for
	// this, since a sem::Block has itself as its associated sem::Block, so it is necessary to
	// look at the parent to get the enclosing block.
	const auto& statement_list =
	sem_parent->Declaration()->As<ast::BlockStatement>()->statements;
	assert(std::find(statement_list.begin(), statement_list.end(), statement_node) !=
	statement_list.end() &&
	"Statement not found.");
	clone_context.Remove(statement_list, statement_node);
	} else {
	// Remove a non-block statement from the block that encloses it.
	const auto& statement_list =
	statement_sem_node->Block()->Declaration()->As<ast::BlockStatement>()->statements;
	assert(std::find(statement_list.begin(), statement_list.end(), statement_node) !=
	statement_list.end() &&
	"Statement not found.");
	clone_context.Remove(statement_list, statement_node);
	}
	}

	protobufs::Mutation MutationDeleteStatement::ToMessage() const {
	protobufs::Mutation mutation;
	*mutation.mutable_delete_statement() = message_;
	return mutation;
	}

	bool MutationDeleteStatement::CanBeDeleted(const ast::Statement& statement_node,
	const Program& program,
	const JumpTracker& jump_tracker) {
	if (statement_node.Is<ast::VariableDeclStatement>()) {
	// This is conservative. It would be possible to delete variable declarations if they are
	// not used. Further analysis could allow that.
	return false;
	}

	if (jump_tracker.ContainsReturn(statement_node)) {
	// This is conservative. It would be possible to delete a return statement as long as there
	// is still a return on every control flow path.
	return false;
	}

	if (jump_tracker.ContainsBreakForInnermostLoop(statement_node)) {
	// This is conservative. Disallowing the removal of breaks ensures that loops cannot become
	// statically infinite. However, a loop might in practice have multiple breaks, some of
	// which can be removed.
	return false;
	}

	if (auto* case_statement = statement_node.As<ast::CaseStatement>()) {
	// It is not OK to delete the case statement which contains the default selector.
	if (case_statement->ContainsDefault()) {
	return false;
	}
	}

	auto* parent_sem = program.Sem().Get(&statement_node)->Parent();
	if (parent_sem == nullptr) {
	// Semantic information for the parent node is required.
	return false;
	}

	auto* parent_stmt = parent_sem->Declaration();

	// It does not make sense to delete the entire body of a loop or if statement.
	if (auto* for_loop = parent_stmt->As<ast::ForLoopStatement>()) {
	if (for_loop->body == &statement_node) {
	return false;
	}
	}
	if (auto* loop = parent_stmt->As<ast::LoopStatement>()) {
	if (loop->body == &statement_node) {
	return false;
	}
	}
	if (auto* while_loop = parent_stmt->As<ast::WhileStatement>()) {
	if (while_loop->body == &statement_node) {
	return false;
	}
	}
	if (auto* if_statement = parent_stmt->As<ast::IfStatement>()) {
	if (if_statement->body == &statement_node) {
	return false;
	}
	}

	return true;
	}

	} // namespace tint::fuzzers::ast_fuzzer