1 files changed, 73 insertions, 0 deletions
diff --git a/gfx/skia/skia/src/sksl/ir/SkSLConstructorArrayCast.cpp b/gfx/skia/skia/src/sksl/ir/SkSLConstructorArrayCast.cpp
new file mode 100644
index 0000000000..a5f9039eb0
--- /dev/null
+++ b/gfx/skia/skia/src/sksl/ir/SkSLConstructorArrayCast.cpp
@@ -0,0 +1,73 @@
+/*
+ * Copyright 2021 Google LLC
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "src/sksl/ir/SkSLConstructorArrayCast.h"
+
+#include "include/core/SkSpan.h"
+#include "include/core/SkTypes.h"
+#include "include/private/SkSLDefines.h"
+#include "src/sksl/SkSLAnalysis.h"
+#include "src/sksl/SkSLConstantFolder.h"
+#include "src/sksl/ir/SkSLConstructorArray.h"
+#include "src/sksl/ir/SkSLConstructorCompoundCast.h"
+#include "src/sksl/ir/SkSLConstructorScalarCast.h"
+#include "src/sksl/ir/SkSLType.h"
+
+namespace SkSL {
+
+static std::unique_ptr<Expression> cast_constant_array(const Context& context,
+                                                       Position pos,
+                                                       const Type& destType,
+                                                       std::unique_ptr<Expression> constCtor) {
+    const Type& scalarType = destType.componentType();
+
+    // Create a ConstructorArray(...) which typecasts each argument inside.
+    auto inputArgs = constCtor->as<ConstructorArray>().argumentSpan();
+    ExpressionArray typecastArgs;
+    typecastArgs.reserve_back(inputArgs.size());
+    for (std::unique_ptr<Expression>& arg : inputArgs) {
+        Position argPos = arg->fPosition;
+        if (arg->type().isScalar()) {
+            typecastArgs.push_back(ConstructorScalarCast::Make(context, argPos, scalarType,
+                                                               std::move(arg)));
+        } else {
+            typecastArgs.push_back(ConstructorCompoundCast::Make(context, argPos, scalarType,
+                                                                 std::move(arg)));
+        }
+    }
+
+    return ConstructorArray::Make(context, pos, destType, std::move(typecastArgs));
+}
+
+std::unique_ptr<Expression> ConstructorArrayCast::Make(const Context& context,
+                                                       Position pos,
+                                                       const Type& type,
+                                                       std::unique_ptr<Expression> arg) {
+    // Only arrays of the same size are allowed.
+    SkASSERT(type.isArray());
+    SkASSERT(type.isAllowedInES2(context));
+    SkASSERT(arg->type().isArray());
+    SkASSERT(type.columns() == arg->type().columns());
+
+    // If this is a no-op cast, return the expression as-is.
+    if (type.matches(arg->type())) {
+        arg->fPosition = pos;
+        return arg;
+    }
+
+    // Look up the value of constant variables. This allows constant-expressions like `myArray` to
+    // be replaced with the compile-time constant `int[2](0, 1)`.
+    arg = ConstantFolder::MakeConstantValueForVariable(pos, std::move(arg));
+
+    // We can cast a vector of compile-time constants at compile-time.
+    if (Analysis::IsCompileTimeConstant(*arg)) {
+        return cast_constant_array(context, pos, type, std::move(arg));
+    }
+    return std::make_unique<ConstructorArrayCast>(pos, type, std::move(arg));
+}
+
+}  // namespace SkSL