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/SkSLConstructorArrayCast.h"
9
10 #include "src/sksl/SkSLConstantFolder.h"
11 #include "src/sksl/SkSLProgramSettings.h"
12 #include "src/sksl/ir/SkSLConstructorArray.h"
13 #include "src/sksl/ir/SkSLConstructorCompoundCast.h"
14 #include "src/sksl/ir/SkSLConstructorScalarCast.h"
15
16 namespace SkSL {
17
cast_constant_array(const Context & context,const Type & destType,std::unique_ptr<Expression> constCtor)18 static std::unique_ptr<Expression> cast_constant_array(const Context& context,
19 const Type& destType,
20 std::unique_ptr<Expression> constCtor) {
21 const Type& scalarType = destType.componentType();
22
23 // Create a ConstructorArray(...) which typecasts each argument inside.
24 auto inputArgs = constCtor->as<ConstructorArray>().argumentSpan();
25 ExpressionArray typecastArgs;
26 typecastArgs.reserve_back(inputArgs.size());
27 for (std::unique_ptr<Expression>& arg : inputArgs) {
28 int line = arg->fLine;
29 if (arg->type().isScalar()) {
30 typecastArgs.push_back(ConstructorScalarCast::Make(context, line, scalarType,
31 std::move(arg)));
32 } else {
33 typecastArgs.push_back(ConstructorCompoundCast::Make(context, line, scalarType,
34 std::move(arg)));
35 }
36 }
37
38 return ConstructorArray::Make(context, constCtor->fLine, destType, std::move(typecastArgs));
39 }
40
Make(const Context & context,int line,const Type & type,std::unique_ptr<Expression> arg)41 std::unique_ptr<Expression> ConstructorArrayCast::Make(const Context& context,
42 int line,
43 const Type& type,
44 std::unique_ptr<Expression> arg) {
45 // Only arrays of the same size are allowed.
46 SkASSERT(type.isArray());
47 SkASSERT(type.isAllowedInES2(context));
48 SkASSERT(arg->type().isArray());
49 SkASSERT(type.columns() == arg->type().columns());
50
51 // If this is a no-op cast, return the expression as-is.
52 if (type == arg->type()) {
53 return arg;
54 }
55
56 // Look up the value of constant variables. This allows constant-expressions like `myArray` to
57 // be replaced with the compile-time constant `int[2](0, 1)`.
58 arg = ConstantFolder::MakeConstantValueForVariable(std::move(arg));
59
60 // We can cast a vector of compile-time constants at compile-time.
61 if (arg->isCompileTimeConstant()) {
62 return cast_constant_array(context, type, std::move(arg));
63 }
64 return std::make_unique<ConstructorArrayCast>(line, type, std::move(arg));
65 }
66
67 } // namespace SkSL
68