| // 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/transform/fold_trivial_single_use_lets.h" |
| |
| #include "src/tint/program_builder.h" |
| #include "src/tint/sem/block_statement.h" |
| #include "src/tint/sem/function.h" |
| #include "src/tint/sem/statement.h" |
| #include "src/tint/sem/variable.h" |
| #include "src/tint/utils/scoped_assignment.h" |
| |
| TINT_INSTANTIATE_TYPEINFO(tint::transform::FoldTrivialSingleUseLets); |
| |
| namespace tint::transform { |
| namespace { |
| |
| const ast::VariableDeclStatement* AsTrivialLetDecl(const ast::Statement* stmt) { |
| auto* var_decl = stmt->As<ast::VariableDeclStatement>(); |
| if (!var_decl) { |
| return nullptr; |
| } |
| auto* var = var_decl->variable; |
| if (!var->is_const) { |
| return nullptr; |
| } |
| auto* ctor = var->constructor; |
| if (!IsAnyOf<ast::IdentifierExpression, ast::LiteralExpression>(ctor)) { |
| return nullptr; |
| } |
| return var_decl; |
| } |
| |
| } // namespace |
| |
| FoldTrivialSingleUseLets::FoldTrivialSingleUseLets() = default; |
| |
| FoldTrivialSingleUseLets::~FoldTrivialSingleUseLets() = default; |
| |
| void FoldTrivialSingleUseLets::Run(CloneContext& ctx, |
| const DataMap&, |
| DataMap&) const { |
| for (auto* node : ctx.src->ASTNodes().Objects()) { |
| if (auto* block = node->As<ast::BlockStatement>()) { |
| auto& stmts = block->statements; |
| for (size_t stmt_idx = 0; stmt_idx < stmts.size(); stmt_idx++) { |
| auto* stmt = stmts[stmt_idx]; |
| if (auto* let_decl = AsTrivialLetDecl(stmt)) { |
| auto* let = let_decl->variable; |
| auto* sem_let = ctx.src->Sem().Get(let); |
| auto& users = sem_let->Users(); |
| if (users.size() != 1) { |
| continue; // Does not have a single user. |
| } |
| |
| auto* user = users[0]; |
| auto* user_stmt = user->Stmt()->Declaration(); |
| |
| for (size_t i = stmt_idx; i < stmts.size(); i++) { |
| if (user_stmt == stmts[i]) { |
| auto* user_expr = user->Declaration(); |
| ctx.Remove(stmts, let_decl); |
| ctx.Replace(user_expr, ctx.Clone(let->constructor)); |
| } |
| if (!AsTrivialLetDecl(stmts[i])) { |
| // Stop if we hit a statement that isn't the single use of the |
| // let, and isn't a let itself. |
| break; |
| } |
| } |
| } |
| } |
| } |
| } |
| |
| ctx.Clone(); |
| } |
| |
| } // namespace tint::transform |