blob: 685b62ed1ddcaa458f338472528b6690bc0c05a6 [file] [log] [blame]
* 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/SkSLConstructorCompoundCast.h"
#include "src/sksl/SkSLConstantFolder.h"
#include "src/sksl/ir/SkSLConstructor.h"
#include "src/sksl/ir/SkSLConstructorCompound.h"
#include "src/sksl/ir/SkSLConstructorDiagonalMatrix.h"
#include "src/sksl/ir/SkSLConstructorScalarCast.h"
#include "src/sksl/ir/SkSLConstructorSplat.h"
namespace SkSL {
static std::unique_ptr<Expression> cast_constant_composite(const Context& context,
const Type& destType,
std::unique_ptr<Expression> constCtor) {
const Type& scalarType = destType.componentType();
// We generate nicer code for splats and diagonal matrices by handling them separately instead
// of relying on the constant-subexpression code below. This is not truly necessary but it makes
// our output look a little better; human beings prefer `half4(0)` to `half4(0, 0, 0, 0)`.
if (constCtor->is<ConstructorSplat>()) {
// This is a typecast of a splat containing a constant value, e.g. `half4(7)`. We can
// replace it with a splat of a different type, e.g. `int4(7)`.
ConstructorSplat& splat = constCtor->as<ConstructorSplat>();
return ConstructorSplat::Make(
context, constCtor->fLine, destType,
ConstructorScalarCast::Make(context, constCtor->fLine, scalarType,
if (constCtor->is<ConstructorDiagonalMatrix>() && destType.isMatrix()) {
// This is a typecast of a constant diagonal matrix, e.g. `float3x3(2)`. We can replace it
// with a diagonal matrix of a different type, e.g. `half3x3(2)`.
ConstructorDiagonalMatrix& matrixCtor = constCtor->as<ConstructorDiagonalMatrix>();
return ConstructorDiagonalMatrix::Make(
context, constCtor->fLine, destType,
ConstructorScalarCast::Make(context, constCtor->fLine, scalarType,
// Create a compound Constructor(literal, ...) which typecasts each scalar value inside.
size_t numSlots = destType.slotCount();
SkASSERT(numSlots == constCtor->type().slotCount());
ExpressionArray typecastArgs;
for (size_t index = 0; index < numSlots; ++index) {
const Expression* arg = constCtor->getConstantSubexpression(index);
typecastArgs.push_back(ConstructorScalarCast::Make(context, constCtor->fLine, scalarType,
return ConstructorCompound::Make(context, constCtor->fLine, destType,
std::unique_ptr<Expression> ConstructorCompoundCast::Make(const Context& context,
int line,
const Type& type,
std::unique_ptr<Expression> arg) {
// Only vectors or matrices of the same dimensions are allowed.
SkASSERT(type.isVector() || type.isMatrix());
SkASSERT(arg->type().isVector() == type.isVector());
SkASSERT(arg->type().isMatrix() == type.isMatrix());
SkASSERT(type.columns() == arg->type().columns());
SkASSERT(type.rows() == arg->type().rows());
// If this is a no-op cast, return the expression as-is.
if (type == arg->type()) {
return arg;
// When optimization is on, look up the value of constant variables. This allows expressions
// like `int4(colorGreen)` to be replaced with the compile-time constant `int4(0, 1, 0, 1)`,
// which is eligible for constant folding.
if (context.fConfig->fSettings.fOptimize) {
arg = ConstantFolder::MakeConstantValueForVariable(std::move(arg));
// We can cast a vector of compile-time constants at compile-time.
if (arg->isCompileTimeConstant()) {
return cast_constant_composite(context, type, std::move(arg));
return std::make_unique<ConstructorCompoundCast>(line, type, std::move(arg));
} // namespace SkSL