1 /*
2 * Copyright 2016 Google Inc.
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 #ifndef SKSL_SWIZZLE
9 #define SKSL_SWIZZLE
10
11 #include "SkSLConstructor.h"
12 #include "SkSLContext.h"
13 #include "SkSLExpression.h"
14 #include "SkSLIRGenerator.h"
15 #include "SkSLUtil.h"
16
17 namespace SkSL {
18
19 /**
20 * Given a type and a swizzle component count, returns the type that will result from swizzling. For
21 * instance, swizzling a float3with two components will result in a float2 It is possible to swizzle
22 * with more components than the source vector, as in 'float21).xxxx'.
23 */
get_type(const Context & context,Expression & value,size_t count)24 static const Type& get_type(const Context& context, Expression& value, size_t count) {
25 const Type& base = value.fType.componentType();
26 if (count == 1) {
27 return base;
28 }
29 if (base == *context.fFloat_Type) {
30 switch (count) {
31 case 2: return *context.fFloat2_Type;
32 case 3: return *context.fFloat3_Type;
33 case 4: return *context.fFloat4_Type;
34 }
35 } else if (base == *context.fHalf_Type) {
36 switch (count) {
37 case 2: return *context.fHalf2_Type;
38 case 3: return *context.fHalf3_Type;
39 case 4: return *context.fHalf4_Type;
40 }
41 } else if (base == *context.fDouble_Type) {
42 switch (count) {
43 case 2: return *context.fDouble2_Type;
44 case 3: return *context.fDouble3_Type;
45 case 4: return *context.fDouble4_Type;
46 }
47 } else if (base == *context.fInt_Type) {
48 switch (count) {
49 case 2: return *context.fInt2_Type;
50 case 3: return *context.fInt3_Type;
51 case 4: return *context.fInt4_Type;
52 }
53 } else if (base == *context.fShort_Type) {
54 switch (count) {
55 case 2: return *context.fShort2_Type;
56 case 3: return *context.fShort3_Type;
57 case 4: return *context.fShort4_Type;
58 }
59 } else if (base == *context.fUInt_Type) {
60 switch (count) {
61 case 2: return *context.fUInt2_Type;
62 case 3: return *context.fUInt3_Type;
63 case 4: return *context.fUInt4_Type;
64 }
65 } else if (base == *context.fUShort_Type) {
66 switch (count) {
67 case 2: return *context.fUShort2_Type;
68 case 3: return *context.fUShort3_Type;
69 case 4: return *context.fUShort4_Type;
70 }
71 } else if (base == *context.fBool_Type) {
72 switch (count) {
73 case 2: return *context.fBool2_Type;
74 case 3: return *context.fBool3_Type;
75 case 4: return *context.fBool4_Type;
76 }
77 }
78 ABORT("cannot swizzle %s\n", value.description().c_str());
79 }
80
81 /**
82 * Represents a vector swizzle operation such as 'float21, 2, 3).zyx'.
83 */
84 struct Swizzle : public Expression {
SwizzleSwizzle85 Swizzle(const Context& context, std::unique_ptr<Expression> base, std::vector<int> components)
86 : INHERITED(base->fOffset, kSwizzle_Kind, get_type(context, *base, components.size()))
87 , fBase(std::move(base))
88 , fComponents(std::move(components)) {
89 ASSERT(fComponents.size() >= 1 && fComponents.size() <= 4);
90 }
91
constantPropagateSwizzle92 std::unique_ptr<Expression> constantPropagate(const IRGenerator& irGenerator,
93 const DefinitionMap& definitions) override {
94 if (fBase->fKind == Expression::kConstructor_Kind && fBase->isConstant()) {
95 // we're swizzling a constant vector, e.g. float4(1).x. Simplify it.
96 ASSERT(fBase->fKind == Expression::kConstructor_Kind);
97 if (fType == *irGenerator.fContext.fInt_Type) {
98 ASSERT(fComponents.size() == 1);
99 int64_t value = ((Constructor&) *fBase).getIVecComponent(fComponents[0]);
100 return std::unique_ptr<Expression>(new IntLiteral(irGenerator.fContext,
101 -1,
102 value));
103 } else if (fType == *irGenerator.fContext.fFloat_Type) {
104 ASSERT(fComponents.size() == 1);
105 double value = ((Constructor&) *fBase).getFVecComponent(fComponents[0]);
106 return std::unique_ptr<Expression>(new FloatLiteral(irGenerator.fContext,
107 -1,
108 value));
109 }
110 }
111 return nullptr;
112 }
113
hasSideEffectsSwizzle114 bool hasSideEffects() const override {
115 return fBase->hasSideEffects();
116 }
117
descriptionSwizzle118 String description() const override {
119 String result = fBase->description() + ".";
120 for (int x : fComponents) {
121 result += "xyzw"[x];
122 }
123 return result;
124 }
125
126 std::unique_ptr<Expression> fBase;
127 const std::vector<int> fComponents;
128
129 typedef Expression INHERITED;
130 };
131
132 } // namespace
133
134 #endif
135