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/SkSLConstructorScalarCast.h"
9
10 #include "include/core/SkTypes.h"
11 #include "include/private/SkSLDefines.h"
12 #include "include/private/base/SkTArray.h"
13 #include "include/sksl/SkSLErrorReporter.h"
14 #include "src/sksl/SkSLConstantFolder.h"
15 #include "src/sksl/SkSLContext.h"
16 #include "src/sksl/ir/SkSLLiteral.h"
17 #include "src/sksl/ir/SkSLType.h"
18
19 #include <string>
20
21 namespace SkSL {
22
Convert(const Context & context,Position pos,const Type & rawType,ExpressionArray args)23 std::unique_ptr<Expression> ConstructorScalarCast::Convert(const Context& context,
24 Position pos,
25 const Type& rawType,
26 ExpressionArray args) {
27 // As you might expect, scalar-cast constructors should only be created with scalar types.
28 const Type& type = rawType.scalarTypeForLiteral();
29 SkASSERT(type.isScalar());
30
31 if (args.size() != 1) {
32 context.fErrors->error(pos, "invalid arguments to '" + type.displayName() +
33 "' constructor, (expected exactly 1 argument, but found " +
34 std::to_string(args.size()) + ")");
35 return nullptr;
36 }
37
38 const Type& argType = args[0]->type();
39 if (!argType.isScalar()) {
40 // Casting a vector-type into its scalar component type is treated as a slice in GLSL.
41 // We don't allow those casts in SkSL; recommend a .x swizzle instead.
42 const char* swizzleHint = "";
43 if (argType.componentType().matches(type)) {
44 if (argType.isVector()) {
45 swizzleHint = "; use '.x' instead";
46 } else if (argType.isMatrix()) {
47 swizzleHint = "; use '[0][0]' instead";
48 }
49 }
50
51 context.fErrors->error(pos,
52 "'" + argType.displayName() + "' is not a valid parameter to '" +
53 type.displayName() + "' constructor" + swizzleHint);
54 return nullptr;
55 }
56 if (type.checkForOutOfRangeLiteral(context, *args[0])) {
57 return nullptr;
58 }
59
60 return ConstructorScalarCast::Make(context, pos, type, std::move(args[0]));
61 }
62
Make(const Context & context,Position pos,const Type & type,std::unique_ptr<Expression> arg)63 std::unique_ptr<Expression> ConstructorScalarCast::Make(const Context& context,
64 Position pos,
65 const Type& type,
66 std::unique_ptr<Expression> arg) {
67 SkASSERT(type.isScalar());
68 SkASSERT(type.isAllowedInES2(context));
69 SkASSERT(arg->type().isScalar());
70
71 // No cast required when the types match.
72 if (arg->type().matches(type)) {
73 return arg;
74 }
75 // Look up the value of constant variables. This allows constant-expressions like `int(zero)` to
76 // be replaced with a literal zero.
77 arg = ConstantFolder::MakeConstantValueForVariable(pos, std::move(arg));
78
79 // We can cast scalar literals at compile-time when possible. (If the resulting literal would be
80 // out of range for its type, we report an error and return zero to minimize error cascading.
81 // This can occur when code is inlined, so we can't necessarily catch it during Convert. As
82 // such, it's not safe to return null or assert.)
83 if (arg->is<Literal>()) {
84 double value = arg->as<Literal>().value();
85 if (type.checkForOutOfRangeLiteral(context, value, arg->fPosition)) {
86 value = 0.0;
87 }
88 return Literal::Make(pos, value, &type);
89 }
90 return std::make_unique<ConstructorScalarCast>(pos, type, std::move(arg));
91 }
92
93 } // namespace SkSL
94