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 "src/sksl/ir/SkSLFieldAccess.h"
9
10 #include "include/core/SkSpan.h"
11 #include "include/core/SkTypes.h"
12 #include "include/private/base/SkTArray.h"
13 #include "src/sksl/SkSLAnalysis.h"
14 #include "src/sksl/SkSLBuiltinTypes.h"
15 #include "src/sksl/SkSLConstantFolder.h"
16 #include "src/sksl/SkSLContext.h"
17 #include "src/sksl/SkSLDefines.h"
18 #include "src/sksl/SkSLErrorReporter.h"
19 #include "src/sksl/SkSLOperator.h"
20 #include "src/sksl/ir/SkSLConstructorStruct.h"
21 #include "src/sksl/ir/SkSLFunctionDeclaration.h"
22 #include "src/sksl/ir/SkSLMethodReference.h"
23 #include "src/sksl/ir/SkSLSetting.h"
24 #include "src/sksl/ir/SkSLSymbol.h"
25 #include "src/sksl/ir/SkSLSymbolTable.h" // IWYU pragma: keep
26
27 #include <cstddef>
28
29 namespace SkSL {
30
Convert(const Context & context,Position pos,std::unique_ptr<Expression> base,std::string_view field)31 std::unique_ptr<Expression> FieldAccess::Convert(const Context& context,
32 Position pos,
33 std::unique_ptr<Expression> base,
34 std::string_view field) {
35 const Type& baseType = base->type();
36 if (baseType.isEffectChild()) {
37 // Turn the field name into a free function name, prefixed with '$':
38 std::string methodName = "$" + std::string(field);
39 const Symbol* result = context.fSymbolTable->find(methodName);
40 if (result && result->is<FunctionDeclaration>()) {
41 return std::make_unique<MethodReference>(context, pos, std::move(base),
42 &result->as<FunctionDeclaration>());
43 }
44 context.fErrors->error(pos, "type '" + baseType.displayName() + "' has no method named '" +
45 std::string(field) + "'");
46 return nullptr;
47 }
48 if (baseType.isStruct()) {
49 SkSpan<const Field> fields = baseType.fields();
50 for (size_t i = 0; i < fields.size(); i++) {
51 if (fields[i].fName == field) {
52 return FieldAccess::Make(context, pos, std::move(base), (int)i);
53 }
54 }
55 }
56 if (baseType.matches(*context.fTypes.fSkCaps)) {
57 return Setting::Convert(context, pos, field);
58 }
59
60 context.fErrors->error(pos, "type '" + baseType.displayName() +
61 "' does not have a field named '" + std::string(field) + "'");
62 return nullptr;
63 }
64
extract_field(Position pos,const ConstructorStruct & ctor,int fieldIndex)65 static std::unique_ptr<Expression> extract_field(Position pos,
66 const ConstructorStruct& ctor,
67 int fieldIndex) {
68 // Confirm that the fields that are being removed are side-effect free.
69 const ExpressionArray& args = ctor.arguments();
70 int numFields = args.size();
71 for (int index = 0; index < numFields; ++index) {
72 if (fieldIndex == index) {
73 continue;
74 }
75 if (Analysis::HasSideEffects(*args[index])) {
76 return nullptr;
77 }
78 }
79
80 // Return the desired field.
81 return args[fieldIndex]->clone(pos);
82 }
83
Make(const Context & context,Position pos,std::unique_ptr<Expression> base,int fieldIndex,OwnerKind ownerKind)84 std::unique_ptr<Expression> FieldAccess::Make(const Context& context,
85 Position pos,
86 std::unique_ptr<Expression> base,
87 int fieldIndex,
88 OwnerKind ownerKind) {
89 SkASSERT(base->type().isStruct());
90 SkASSERT(fieldIndex >= 0);
91 SkASSERT(fieldIndex < (int)base->type().fields().size());
92
93 // Replace `knownStruct.field` with the field's value if there are no side-effects involved.
94 const Expression* expr = ConstantFolder::GetConstantValueForVariable(*base);
95 if (expr->is<ConstructorStruct>()) {
96 if (std::unique_ptr<Expression> field = extract_field(pos, expr->as<ConstructorStruct>(),
97 fieldIndex)) {
98 return field;
99 }
100 }
101
102 return std::make_unique<FieldAccess>(pos, std::move(base), fieldIndex, ownerKind);
103 }
104
initialSlot() const105 size_t FieldAccess::initialSlot() const {
106 SkSpan<const Field> fields = this->base()->type().fields();
107 const int fieldIndex = this->fieldIndex();
108
109 size_t slot = 0;
110 for (int index = 0; index < fieldIndex; ++index) {
111 slot += fields[index].fType->slotCount();
112 }
113 return slot;
114 }
115
description(OperatorPrecedence) const116 std::string FieldAccess::description(OperatorPrecedence) const {
117 std::string f = this->base()->description(OperatorPrecedence::kPostfix);
118 if (!f.empty()) {
119 f.push_back('.');
120 }
121 return f + std::string(this->base()->type().fields()[this->fieldIndex()].fName);
122 }
123
124 } // namespace SkSL
125