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/SkSLConstantFolder.h"
9 #include "src/sksl/ir/SkSLIndexExpression.h"
10 #include "src/sksl/ir/SkSLSwizzle.h"
11
12 namespace SkSL {
13
IndexType(const Context & context,const Type & type)14 const Type& IndexExpression::IndexType(const Context& context, const Type& type) {
15 if (type.isMatrix()) {
16 if (type.componentType() == *context.fTypes.fFloat) {
17 switch (type.rows()) {
18 case 2: return *context.fTypes.fFloat2;
19 case 3: return *context.fTypes.fFloat3;
20 case 4: return *context.fTypes.fFloat4;
21 default: SkASSERT(false);
22 }
23 } else if (type.componentType() == *context.fTypes.fHalf) {
24 switch (type.rows()) {
25 case 2: return *context.fTypes.fHalf2;
26 case 3: return *context.fTypes.fHalf3;
27 case 4: return *context.fTypes.fHalf4;
28 default: SkASSERT(false);
29 }
30 }
31 }
32 return type.componentType();
33 }
34
Convert(const Context & context,std::unique_ptr<Expression> base,std::unique_ptr<Expression> index)35 std::unique_ptr<Expression> IndexExpression::Convert(const Context& context,
36 std::unique_ptr<Expression> base,
37 std::unique_ptr<Expression> index) {
38 // Convert an index expression with an expression inside of it: `arr[a * 3]`.
39 const Type& baseType = base->type();
40 if (!baseType.isArray() && !baseType.isMatrix() && !baseType.isVector()) {
41 context.fErrors.error(base->fOffset,
42 "expected array, but found '" + baseType.displayName() + "'");
43 return nullptr;
44 }
45 if (!index->type().isInteger()) {
46 index = context.fTypes.fInt->coerceExpression(std::move(index), context);
47 if (!index) {
48 return nullptr;
49 }
50 }
51 // Perform compile-time bounds checking on constant-expression indices.
52 const Expression* indexExpr = ConstantFolder::GetConstantValueForVariable(*index);
53 if (indexExpr->is<IntLiteral>()) {
54 SKSL_INT indexValue = indexExpr->as<IntLiteral>().value();
55 const int upperBound = (baseType.isArray() && baseType.columns() == Type::kUnsizedArray)
56 ? INT_MAX
57 : baseType.columns();
58 if (indexValue < 0 || indexValue >= upperBound) {
59 context.fErrors.error(base->fOffset, "index " + to_string(indexValue) + " out of range "
60 "for '" + baseType.displayName() + "'");
61 return nullptr;
62 }
63 }
64 return IndexExpression::Make(context, std::move(base), std::move(index));
65 }
66
Make(const Context & context,std::unique_ptr<Expression> base,std::unique_ptr<Expression> index)67 std::unique_ptr<Expression> IndexExpression::Make(const Context& context,
68 std::unique_ptr<Expression> base,
69 std::unique_ptr<Expression> index) {
70 const Type& baseType = base->type();
71 SkASSERT(baseType.isArray() || baseType.isMatrix() || baseType.isVector());
72 SkASSERT(index->type().isInteger());
73
74 if (context.fConfig->fSettings.fOptimize) {
75 // Constant array indexes on vectors can be converted to swizzles: `v[2]` --> `v.z`.
76 // Swizzling is harmless and can unlock further simplifications for some base types.
77 const Expression* indexExpr = ConstantFolder::GetConstantValueForVariable(*index);
78 if (indexExpr->is<IntLiteral>() && baseType.isVector()) {
79 SKSL_INT indexValue = indexExpr->as<IntLiteral>().value();
80 return Swizzle::Make(context, std::move(base), ComponentArray{(int8_t)indexValue});
81 }
82 }
83
84 return std::make_unique<IndexExpression>(context, std::move(base), std::move(index));
85 }
86
87 } // namespace SkSL
88