1 /* 2 * Copyright 2022 Google LLC 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8 #include "include/core/SkSpan.h" 9 #include "src/sksl/SkSLDefines.h" 10 #include "src/sksl/SkSLModule.h" 11 #include "src/sksl/ir/SkSLBlock.h" 12 #include "src/sksl/ir/SkSLFunctionDefinition.h" 13 #include "src/sksl/ir/SkSLProgramElement.h" 14 #include "src/sksl/ir/SkSLStatement.h" 15 #include "src/sksl/transform/SkSLProgramWriter.h" 16 #include "src/sksl/transform/SkSLTransform.h" 17 18 #include <algorithm> 19 #include <iterator> 20 #include <memory> 21 #include <vector> 22 23 namespace SkSL { 24 25 class Expression; 26 eliminate_empty_statements(SkSpan<std::unique_ptr<ProgramElement>> elements)27static void eliminate_empty_statements(SkSpan<std::unique_ptr<ProgramElement>> elements) { 28 class EmptyStatementEliminator : public ProgramWriter { 29 public: 30 bool visitExpressionPtr(std::unique_ptr<Expression>& expr) override { 31 // We don't need to look inside expressions at all. 32 return false; 33 } 34 35 bool visitStatementPtr(std::unique_ptr<Statement>& stmt) override { 36 // Work from the innermost blocks to the outermost. 37 INHERITED::visitStatementPtr(stmt); 38 39 if (stmt->is<Block>()) { 40 StatementArray& children = stmt->as<Block>().children(); 41 auto iter = std::remove_if(children.begin(), children.end(), 42 [](std::unique_ptr<Statement>& stmt) { 43 return stmt->isEmpty(); 44 }); 45 children.resize(std::distance(children.begin(), iter)); 46 } 47 48 // We always check the entire program. 49 return false; 50 } 51 52 using INHERITED = ProgramWriter; 53 }; 54 55 for (std::unique_ptr<ProgramElement>& pe : elements) { 56 if (pe->is<FunctionDefinition>()) { 57 EmptyStatementEliminator visitor; 58 visitor.visitStatementPtr(pe->as<FunctionDefinition>().body()); 59 } 60 } 61 } 62 EliminateEmptyStatements(Module & module)63void Transform::EliminateEmptyStatements(Module& module) { 64 return eliminate_empty_statements(SkSpan(module.fElements)); 65 } 66 67 } // namespace SkSL 68