1/*
2 * Copyright 2021 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/private/SkSLProgramElement.h"
9#include "src/sksl/SkSLProgramSettings.h"
10#include "src/sksl/ir/SkSLProgram.h"
11#include "src/sksl/ir/SkSLVarDeclarations.h"
12#include "src/sksl/transform/SkSLTransform.h"
13
14#include <algorithm>
15
16namespace SkSL {
17
18bool Transform::EliminateDeadGlobalVariables(Program& program, ProgramUsage* usage) {
19    bool madeChanges = false;
20
21    if (program.fConfig->fSettings.fRemoveDeadVariables) {
22        auto isDeadVariable = [&](const ProgramElement* element) {
23            if (!element->is<GlobalVarDeclaration>()) {
24                return false;
25            }
26            const GlobalVarDeclaration& global = element->as<GlobalVarDeclaration>();
27            const VarDeclaration& varDecl = global.declaration()->as<VarDeclaration>();
28            if (!usage->isDead(varDecl.var())) {
29                return false;
30            }
31            madeChanges = true;
32            return true;
33        };
34
35        program.fOwnedElements.erase(std::remove_if(program.fOwnedElements.begin(),
36                                                    program.fOwnedElements.end(),
37                                                    [&](const std::unique_ptr<ProgramElement>& pe) {
38                                                        return isDeadVariable(pe.get());
39                                                    }),
40                                     program.fOwnedElements.end());
41        program.fSharedElements.erase(std::remove_if(program.fSharedElements.begin(),
42                                                     program.fSharedElements.end(),
43                                                     isDeadVariable),
44                                      program.fSharedElements.end());
45    }
46    return madeChanges;
47}
48
49}  // namespace SkSL
50