| /* |
| * Copyright 2020 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/SkSLConstantFolder.h" |
| |
| #include "include/core/SkTypes.h" |
| #include "include/private/SkSLModifiers.h" |
| #include "include/sksl/SkSLErrorReporter.h" |
| #include "include/sksl/SkSLPosition.h" |
| #include "src/sksl/SkSLAnalysis.h" |
| #include "src/sksl/SkSLContext.h" |
| #include "src/sksl/SkSLProgramSettings.h" |
| #include "src/sksl/ir/SkSLConstructorCompound.h" |
| #include "src/sksl/ir/SkSLConstructorDiagonalMatrix.h" |
| #include "src/sksl/ir/SkSLConstructorSplat.h" |
| #include "src/sksl/ir/SkSLExpression.h" |
| #include "src/sksl/ir/SkSLLiteral.h" |
| #include "src/sksl/ir/SkSLPrefixExpression.h" |
| #include "src/sksl/ir/SkSLType.h" |
| #include "src/sksl/ir/SkSLVariable.h" |
| #include "src/sksl/ir/SkSLVariableReference.h" |
| |
| #include <cfloat> |
| #include <cmath> |
| #include <cstdint> |
| #include <limits> |
| #include <optional> |
| #include <string> |
| #include <type_traits> |
| #include <utility> |
| |
| namespace SkSL { |
| |
| static bool is_vec_or_mat(const Type& type) { |
| switch (type.typeKind()) { |
| case Type::TypeKind::kMatrix: |
| case Type::TypeKind::kVector: |
| return true; |
| |
| default: |
| return false; |
| } |
| } |
| |
| static std::unique_ptr<Expression> eliminate_no_op_boolean(Position pos, |
| const Expression& left, |
| Operator op, |
| const Expression& right) { |
| bool rightVal = right.as<Literal>().boolValue(); |
| |
| // Detect no-op Boolean expressions and optimize them away. |
| if ((op.kind() == Operator::Kind::LOGICALAND && rightVal) || // (expr && true) -> (expr) |
| (op.kind() == Operator::Kind::LOGICALOR && !rightVal) || // (expr || false) -> (expr) |
| (op.kind() == Operator::Kind::LOGICALXOR && !rightVal) || // (expr ^^ false) -> (expr) |
| (op.kind() == Operator::Kind::EQEQ && rightVal) || // (expr == true) -> (expr) |
| (op.kind() == Operator::Kind::NEQ && !rightVal)) { // (expr != false) -> (expr) |
| |
| return left.clone(pos); |
| } |
| |
| return nullptr; |
| } |
| |
| static std::unique_ptr<Expression> short_circuit_boolean(Position pos, |
| const Expression& left, |
| Operator op, |
| const Expression& right) { |
| bool leftVal = left.as<Literal>().boolValue(); |
| |
| // When the literal is on the left, we can sometimes eliminate the other expression entirely. |
| if ((op.kind() == Operator::Kind::LOGICALAND && !leftVal) || // (false && expr) -> (false) |
| (op.kind() == Operator::Kind::LOGICALOR && leftVal)) { // (true || expr) -> (true) |
| |
| return left.clone(pos); |
| } |
| |
| // We can't eliminate the right-side expression via short-circuit, but we might still be able to |
| // simplify away a no-op expression. |
| return eliminate_no_op_boolean(pos, right, op, left); |
| } |
| |
| static std::unique_ptr<Expression> simplify_constant_equality(const Context& context, |
| Position pos, |
| const Expression& left, |
| Operator op, |
| const Expression& right) { |
| if (op.kind() == Operator::Kind::EQEQ || op.kind() == Operator::Kind::NEQ) { |
| bool equality = (op.kind() == Operator::Kind::EQEQ); |
| |
| switch (left.compareConstant(right)) { |
| case Expression::ComparisonResult::kNotEqual: |
| equality = !equality; |
| [[fallthrough]]; |
| |
| case Expression::ComparisonResult::kEqual: |
| return Literal::MakeBool(context, pos, equality); |
| |
| case Expression::ComparisonResult::kUnknown: |
| break; |
| } |
| } |
| return nullptr; |
| } |
| |
| static std::unique_ptr<Expression> simplify_matrix_multiplication(const Context& context, |
| Position pos, |
| const Expression& left, |
| const Expression& right, |
| int leftColumns, |
| int leftRows, |
| int rightColumns, |
| int rightRows) { |
| const Type& componentType = left.type().componentType(); |
| SkASSERT(componentType.matches(right.type().componentType())); |
| |
| // Fetch the left matrix. |
| double leftVals[4][4]; |
| for (int c = 0; c < leftColumns; ++c) { |
| for (int r = 0; r < leftRows; ++r) { |
| leftVals[c][r] = *left.getConstantValue((c * leftRows) + r); |
| } |
| } |
| // Fetch the right matrix. |
| double rightVals[4][4]; |
| for (int c = 0; c < rightColumns; ++c) { |
| for (int r = 0; r < rightRows; ++r) { |
| rightVals[c][r] = *right.getConstantValue((c * rightRows) + r); |
| } |
| } |
| |
| SkASSERT(leftColumns == rightRows); |
| int outColumns = rightColumns, |
| outRows = leftRows; |
| |
| ExpressionArray args; |
| args.reserve_back(outColumns * outRows); |
| for (int c = 0; c < outColumns; ++c) { |
| for (int r = 0; r < outRows; ++r) { |
| // Compute a dot product for this position. |
| double val = 0; |
| for (int dotIdx = 0; dotIdx < leftColumns; ++dotIdx) { |
| val += leftVals[dotIdx][r] * rightVals[c][dotIdx]; |
| } |
| args.push_back(Literal::Make(pos, val, &componentType)); |
| } |
| } |
| |
| if (outColumns == 1) { |
| // Matrix-times-vector conceptually makes a 1-column N-row matrix, but we return vecN. |
| std::swap(outColumns, outRows); |
| } |
| |
| const Type& resultType = componentType.toCompound(context, outColumns, outRows); |
| return ConstructorCompound::Make(context, pos, resultType, std::move(args)); |
| } |
| |
| static std::unique_ptr<Expression> simplify_matrix_times_matrix(const Context& context, |
| Position pos, |
| const Expression& left, |
| const Expression& right) { |
| const Type& leftType = left.type(); |
| const Type& rightType = right.type(); |
| |
| SkASSERT(leftType.isMatrix()); |
| SkASSERT(rightType.isMatrix()); |
| |
| return simplify_matrix_multiplication(context, pos, left, right, |
| leftType.columns(), leftType.rows(), |
| rightType.columns(), rightType.rows()); |
| } |
| |
| static std::unique_ptr<Expression> simplify_vector_times_matrix(const Context& context, |
| Position pos, |
| const Expression& left, |
| const Expression& right) { |
| const Type& leftType = left.type(); |
| const Type& rightType = right.type(); |
| |
| SkASSERT(leftType.isVector()); |
| SkASSERT(rightType.isMatrix()); |
| |
| return simplify_matrix_multiplication(context, pos, left, right, |
| /*leftColumns=*/leftType.columns(), /*leftRows=*/1, |
| rightType.columns(), rightType.rows()); |
| } |
| |
| static std::unique_ptr<Expression> simplify_matrix_times_vector(const Context& context, |
| Position pos, |
| const Expression& left, |
| const Expression& right) { |
| const Type& leftType = left.type(); |
| const Type& rightType = right.type(); |
| |
| SkASSERT(leftType.isMatrix()); |
| SkASSERT(rightType.isVector()); |
| |
| return simplify_matrix_multiplication(context, pos, left, right, |
| leftType.columns(), leftType.rows(), |
| /*rightColumns=*/1, /*rightRows=*/rightType.columns()); |
| } |
| |
| static std::unique_ptr<Expression> simplify_componentwise(const Context& context, |
| Position pos, |
| const Expression& left, |
| Operator op, |
| const Expression& right) { |
| SkASSERT(is_vec_or_mat(left.type())); |
| SkASSERT(left.type().matches(right.type())); |
| const Type& type = left.type(); |
| |
| // Handle equality operations: == != |
| if (std::unique_ptr<Expression> result = simplify_constant_equality(context, pos, left, op, |
| right)) { |
| return result; |
| } |
| |
| // Handle floating-point arithmetic: + - * / |
| using FoldFn = double (*)(double, double); |
| FoldFn foldFn; |
| switch (op.kind()) { |
| case Operator::Kind::PLUS: foldFn = +[](double a, double b) { return a + b; }; break; |
| case Operator::Kind::MINUS: foldFn = +[](double a, double b) { return a - b; }; break; |
| case Operator::Kind::STAR: foldFn = +[](double a, double b) { return a * b; }; break; |
| case Operator::Kind::SLASH: foldFn = +[](double a, double b) { return a / b; }; break; |
| default: |
| return nullptr; |
| } |
| |
| const Type& componentType = type.componentType(); |
| SkASSERT(componentType.isNumber()); |
| |
| double minimumValue = -INFINITY, maximumValue = INFINITY; |
| if (componentType.isInteger()) { |
| minimumValue = componentType.minimumValue(); |
| maximumValue = componentType.maximumValue(); |
| } |
| |
| ExpressionArray args; |
| int numSlots = type.slotCount(); |
| args.reserve_back(numSlots); |
| for (int i = 0; i < numSlots; i++) { |
| double value = foldFn(*left.getConstantValue(i), *right.getConstantValue(i)); |
| if (value < minimumValue || value > maximumValue) { |
| return nullptr; |
| } |
| |
| args.push_back(Literal::Make(pos, value, &componentType)); |
| } |
| return ConstructorCompound::Make(context, pos, type, std::move(args)); |
| } |
| |
| static std::unique_ptr<Expression> splat_scalar(const Context& context, |
| const Expression& scalar, |
| const Type& type) { |
| if (type.isVector()) { |
| return ConstructorSplat::Make(context, scalar.fPosition, type, scalar.clone()); |
| } |
| if (type.isMatrix()) { |
| int numSlots = type.slotCount(); |
| ExpressionArray splatMatrix; |
| splatMatrix.reserve_back(numSlots); |
| for (int index = 0; index < numSlots; ++index) { |
| splatMatrix.push_back(scalar.clone()); |
| } |
| return ConstructorCompound::Make(context, scalar.fPosition, type, std::move(splatMatrix)); |
| } |
| SkDEBUGFAILF("unsupported type %s", type.description().c_str()); |
| return nullptr; |
| } |
| |
| static std::unique_ptr<Expression> cast_expression(const Context& context, |
| Position pos, |
| const Expression& expr, |
| const Type& type) { |
| SkASSERT(type.componentType().matches(expr.type().componentType())); |
| if (expr.type().isScalar()) { |
| if (type.isMatrix()) { |
| return ConstructorDiagonalMatrix::Make(context, pos, type, expr.clone()); |
| } |
| if (type.isVector()) { |
| return ConstructorSplat::Make(context, pos, type, expr.clone()); |
| } |
| } |
| if (type.matches(expr.type())) { |
| return expr.clone(pos); |
| } |
| // We can't cast matrices into vectors or vice-versa. |
| return nullptr; |
| } |
| |
| static std::unique_ptr<Expression> zero_expression(const Context& context, |
| Position pos, |
| const Type& type) { |
| std::unique_ptr<Expression> zero = Literal::Make(pos, 0.0, &type.componentType()); |
| if (type.isScalar()) { |
| return zero; |
| } |
| if (type.isVector()) { |
| return ConstructorSplat::Make(context, pos, type, std::move(zero)); |
| } |
| if (type.isMatrix()) { |
| return ConstructorDiagonalMatrix::Make(context, pos, type, std::move(zero)); |
| } |
| SkDEBUGFAILF("unsupported type %s", type.description().c_str()); |
| return nullptr; |
| } |
| |
| static std::unique_ptr<Expression> negate_expression(const Context& context, |
| Position pos, |
| const Expression& expr, |
| const Type& type) { |
| std::unique_ptr<Expression> ctor = cast_expression(context, pos, expr, type); |
| return ctor ? PrefixExpression::Make(context, pos, Operator::Kind::MINUS, std::move(ctor)) |
| : nullptr; |
| } |
| |
| bool ConstantFolder::GetConstantInt(const Expression& value, SKSL_INT* out) { |
| const Expression* expr = GetConstantValueForVariable(value); |
| if (!expr->isIntLiteral()) { |
| return false; |
| } |
| *out = expr->as<Literal>().intValue(); |
| return true; |
| } |
| |
| bool ConstantFolder::GetConstantValue(const Expression& value, double* out) { |
| const Expression* expr = GetConstantValueForVariable(value); |
| if (!expr->is<Literal>()) { |
| return false; |
| } |
| *out = expr->as<Literal>().value(); |
| return true; |
| } |
| |
| static bool contains_constant_zero(const Expression& expr) { |
| int numSlots = expr.type().slotCount(); |
| for (int index = 0; index < numSlots; ++index) { |
| std::optional<double> slotVal = expr.getConstantValue(index); |
| if (slotVal.has_value() && *slotVal == 0.0) { |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| // Returns true if the expression contains `value` in every slot. |
| static bool is_constant_splat(const Expression& expr, double value) { |
| int numSlots = expr.type().slotCount(); |
| for (int index = 0; index < numSlots; ++index) { |
| std::optional<double> slotVal = expr.getConstantValue(index); |
| if (!slotVal.has_value() || *slotVal != value) { |
| return false; |
| } |
| } |
| return true; |
| } |
| |
| // Returns true if the expression is a square diagonal matrix containing `value`. |
| static bool is_constant_diagonal(const Expression& expr, double value) { |
| SkASSERT(expr.type().isMatrix()); |
| int columns = expr.type().columns(); |
| int rows = expr.type().rows(); |
| if (columns != rows) { |
| return false; |
| } |
| int slotIdx = 0; |
| for (int c = 0; c < columns; ++c) { |
| for (int r = 0; r < rows; ++r) { |
| double expectation = (c == r) ? value : 0; |
| std::optional<double> slotVal = expr.getConstantValue(slotIdx++); |
| if (!slotVal.has_value() || *slotVal != expectation) { |
| return false; |
| } |
| } |
| } |
| return true; |
| } |
| |
| // Returns true if the expression is a scalar, vector, or diagonal matrix containing `value`. |
| static bool is_constant_value(const Expression& expr, double value) { |
| return expr.type().isMatrix() ? is_constant_diagonal(expr, value) |
| : is_constant_splat(expr, value); |
| } |
| |
| static bool error_on_divide_by_zero(const Context& context, Position pos, Operator op, |
| const Expression& right) { |
| switch (op.kind()) { |
| case Operator::Kind::SLASH: |
| case Operator::Kind::SLASHEQ: |
| case Operator::Kind::PERCENT: |
| case Operator::Kind::PERCENTEQ: |
| if (contains_constant_zero(right)) { |
| context.fErrors->error(pos, "division by zero"); |
| return true; |
| } |
| return false; |
| default: |
| return false; |
| } |
| } |
| |
| const Expression* ConstantFolder::GetConstantValueForVariable(const Expression& inExpr) { |
| for (const Expression* expr = &inExpr;;) { |
| if (!expr->is<VariableReference>()) { |
| break; |
| } |
| const VariableReference& varRef = expr->as<VariableReference>(); |
| if (varRef.refKind() != VariableRefKind::kRead) { |
| break; |
| } |
| const Variable& var = *varRef.variable(); |
| if (!(var.modifiers().fFlags & Modifiers::kConst_Flag)) { |
| break; |
| } |
| expr = var.initialValue(); |
| if (!expr) { |
| // Function parameters can be const but won't have an initial value. |
| break; |
| } |
| if (expr->isCompileTimeConstant()) { |
| return expr; |
| } |
| } |
| // We didn't find a compile-time constant at the end. Return the expression as-is. |
| return &inExpr; |
| } |
| |
| std::unique_ptr<Expression> ConstantFolder::MakeConstantValueForVariable(Position pos, |
| std::unique_ptr<Expression> expr) { |
| const Expression* constantExpr = GetConstantValueForVariable(*expr); |
| if (constantExpr != expr.get()) { |
| expr = constantExpr->clone(pos); |
| } |
| return expr; |
| } |
| |
| static bool is_scalar_op_matrix(const Expression& left, const Expression& right) { |
| return left.type().isScalar() && right.type().isMatrix(); |
| } |
| |
| static bool is_matrix_op_scalar(const Expression& left, const Expression& right) { |
| return is_scalar_op_matrix(right, left); |
| } |
| |
| static std::unique_ptr<Expression> simplify_no_op_arithmetic(const Context& context, |
| Position pos, |
| const Expression& left, |
| Operator op, |
| const Expression& right, |
| const Type& resultType) { |
| switch (op.kind()) { |
| case Operator::Kind::PLUS: |
| if (!is_scalar_op_matrix(left, right) && is_constant_splat(right, 0.0)) { // x + 0 |
| if (std::unique_ptr<Expression> expr = cast_expression(context, pos, left, |
| resultType)) { |
| return expr; |
| } |
| } |
| if (!is_matrix_op_scalar(left, right) && is_constant_splat(left, 0.0)) { // 0 + x |
| if (std::unique_ptr<Expression> expr = cast_expression(context, pos, right, |
| resultType)) { |
| return expr; |
| } |
| } |
| break; |
| |
| case Operator::Kind::STAR: |
| if (is_constant_value(right, 1.0)) { // x * 1 |
| if (std::unique_ptr<Expression> expr = cast_expression(context, pos, left, |
| resultType)) { |
| return expr; |
| } |
| } |
| if (is_constant_value(left, 1.0)) { // 1 * x |
| if (std::unique_ptr<Expression> expr = cast_expression(context, pos, right, |
| resultType)) { |
| return expr; |
| } |
| } |
| if (is_constant_value(right, 0.0) && !left.hasSideEffects()) { // x * 0 |
| return zero_expression(context, pos, resultType); |
| } |
| if (is_constant_value(left, 0.0) && !right.hasSideEffects()) { // 0 * x |
| return zero_expression(context, pos, resultType); |
| } |
| if (is_constant_value(right, -1.0)) { // x * -1 (to `-x`) |
| if (std::unique_ptr<Expression> expr = negate_expression(context, pos, left, |
| resultType)) { |
| return expr; |
| } |
| } |
| if (is_constant_value(left, -1.0)) { // -1 * x (to `-x`) |
| if (std::unique_ptr<Expression> expr = negate_expression(context, pos, right, |
| resultType)) { |
| return expr; |
| } |
| } |
| break; |
| |
| case Operator::Kind::MINUS: |
| if (!is_scalar_op_matrix(left, right) && is_constant_splat(right, 0.0)) { // x - 0 |
| if (std::unique_ptr<Expression> expr = cast_expression(context, pos, left, |
| resultType)) { |
| return expr; |
| } |
| } |
| if (!is_matrix_op_scalar(left, right) && is_constant_splat(left, 0.0)) { // 0 - x |
| if (std::unique_ptr<Expression> expr = negate_expression(context, pos, right, |
| resultType)) { |
| return expr; |
| } |
| } |
| break; |
| |
| case Operator::Kind::SLASH: |
| if (!is_scalar_op_matrix(left, right) && is_constant_splat(right, 1.0)) { // x / 1 |
| if (std::unique_ptr<Expression> expr = cast_expression(context, pos, left, |
| resultType)) { |
| return expr; |
| } |
| } |
| break; |
| |
| case Operator::Kind::PLUSEQ: |
| case Operator::Kind::MINUSEQ: |
| if (is_constant_splat(right, 0.0)) { // x += 0, x -= 0 |
| if (std::unique_ptr<Expression> var = cast_expression(context, pos, left, |
| resultType)) { |
| Analysis::UpdateVariableRefKind(var.get(), VariableRefKind::kRead); |
| return var; |
| } |
| } |
| break; |
| |
| case Operator::Kind::STAREQ: |
| if (is_constant_value(right, 1.0)) { // x *= 1 |
| if (std::unique_ptr<Expression> var = cast_expression(context, pos, left, |
| resultType)) { |
| Analysis::UpdateVariableRefKind(var.get(), VariableRefKind::kRead); |
| return var; |
| } |
| } |
| break; |
| |
| case Operator::Kind::SLASHEQ: |
| if (is_constant_splat(right, 1.0)) { // x /= 1 |
| if (std::unique_ptr<Expression> var = cast_expression(context, pos, left, |
| resultType)) { |
| Analysis::UpdateVariableRefKind(var.get(), VariableRefKind::kRead); |
| return var; |
| } |
| } |
| break; |
| |
| default: |
| break; |
| } |
| |
| return nullptr; |
| } |
| |
| template <typename T> |
| static std::unique_ptr<Expression> fold_float_expression(Position pos, |
| T result, |
| const Type* resultType) { |
| if constexpr (!std::is_same<T, bool>::value) { |
| if (result >= -FLT_MAX && result <= FLT_MAX) { |
| // This result will fit inside a float Literal. |
| } else { |
| // The value is outside the float range or is NaN (all if-checks fail); do not optimize. |
| return nullptr; |
| } |
| } |
| |
| return Literal::Make(pos, result, resultType); |
| } |
| |
| template <typename T> |
| static std::unique_ptr<Expression> fold_int_expression(Position pos, |
| T result, |
| const Type* resultType) { |
| // If constant-folding this expression would overflow the result type, leave it as-is. |
| if constexpr (!std::is_same<T, bool>::value) { |
| if (result < resultType->minimumValue() || result > resultType->maximumValue()) { |
| return nullptr; |
| } |
| } |
| |
| return Literal::Make(pos, result, resultType); |
| } |
| |
| std::unique_ptr<Expression> ConstantFolder::Simplify(const Context& context, |
| Position pos, |
| const Expression& leftExpr, |
| Operator op, |
| const Expression& rightExpr, |
| const Type& resultType) { |
| // Replace constant variables with their literal values. |
| const Expression* left = GetConstantValueForVariable(leftExpr); |
| const Expression* right = GetConstantValueForVariable(rightExpr); |
| |
| // If this is the assignment operator, and both sides are the same trivial expression, this is |
| // self-assignment (i.e., `var = var`) and can be reduced to just a variable reference (`var`). |
| // This can happen when other parts of the assignment are optimized away. |
| if (op.kind() == Operator::Kind::EQ && Analysis::IsSameExpressionTree(*left, *right)) { |
| return right->clone(pos); |
| } |
| |
| // Simplify the expression when both sides are constant Boolean literals. |
| if (left->isBoolLiteral() && right->isBoolLiteral()) { |
| bool leftVal = left->as<Literal>().boolValue(); |
| bool rightVal = right->as<Literal>().boolValue(); |
| bool result; |
| switch (op.kind()) { |
| case Operator::Kind::LOGICALAND: result = leftVal && rightVal; break; |
| case Operator::Kind::LOGICALOR: result = leftVal || rightVal; break; |
| case Operator::Kind::LOGICALXOR: result = leftVal ^ rightVal; break; |
| case Operator::Kind::EQEQ: result = leftVal == rightVal; break; |
| case Operator::Kind::NEQ: result = leftVal != rightVal; break; |
| default: return nullptr; |
| } |
| return Literal::MakeBool(context, pos, result); |
| } |
| |
| // If the left side is a Boolean literal, apply short-circuit optimizations. |
| if (left->isBoolLiteral()) { |
| return short_circuit_boolean(pos, *left, op, *right); |
| } |
| |
| // If the right side is a Boolean literal... |
| if (right->isBoolLiteral()) { |
| // ... and the left side has no side effects... |
| if (!left->hasSideEffects()) { |
| // We can reverse the expressions and short-circuit optimizations are still valid. |
| return short_circuit_boolean(pos, *right, op, *left); |
| } |
| |
| // We can't use short-circuiting, but we can still optimize away no-op Boolean expressions. |
| return eliminate_no_op_boolean(pos, *left, op, *right); |
| } |
| |
| if (op.kind() == Operator::Kind::EQEQ && Analysis::IsSameExpressionTree(*left, *right)) { |
| // With == comparison, if both sides are the same trivial expression, this is self- |
| // comparison and is always true. (We are not concerned with NaN.) |
| return Literal::MakeBool(context, pos, /*value=*/true); |
| } |
| |
| if (op.kind() == Operator::Kind::NEQ && Analysis::IsSameExpressionTree(*left, *right)) { |
| // With != comparison, if both sides are the same trivial expression, this is self- |
| // comparison and is always false. (We are not concerned with NaN.) |
| return Literal::MakeBool(context, pos, /*value=*/false); |
| } |
| |
| if (error_on_divide_by_zero(context, pos, op, *right)) { |
| return nullptr; |
| } |
| |
| // Optimize away no-op arithmetic like `x * 1`, `x *= 1`, `x + 0`, `x * 0`, `0 / x`, etc. |
| const Type& leftType = left->type(); |
| const Type& rightType = right->type(); |
| if (context.fConfig->fSettings.fOptimize) { |
| if (std::unique_ptr<Expression> expr = simplify_no_op_arithmetic(context, pos, *left, op, |
| *right, resultType)) { |
| return expr; |
| } |
| } |
| |
| // Other than the cases above, constant folding requires both sides to be constant. |
| if (!left->isCompileTimeConstant() || !right->isCompileTimeConstant()) { |
| return nullptr; |
| } |
| |
| // Note that fold_int_expression returns null if the result would overflow its type. |
| using SKSL_UINT = uint64_t; |
| if (left->isIntLiteral() && right->isIntLiteral()) { |
| SKSL_INT leftVal = left->as<Literal>().intValue(); |
| SKSL_INT rightVal = right->as<Literal>().intValue(); |
| |
| #define RESULT(Op) fold_int_expression(pos, \ |
| (SKSL_INT)(leftVal) Op (SKSL_INT)(rightVal), &resultType) |
| #define URESULT(Op) fold_int_expression(pos, \ |
| (SKSL_INT)((SKSL_UINT)(leftVal) Op (SKSL_UINT)(rightVal)), &resultType) |
| switch (op.kind()) { |
| case Operator::Kind::PLUS: return URESULT(+); |
| case Operator::Kind::MINUS: return URESULT(-); |
| case Operator::Kind::STAR: return URESULT(*); |
| case Operator::Kind::SLASH: |
| if (leftVal == std::numeric_limits<SKSL_INT>::min() && rightVal == -1) { |
| context.fErrors->error(pos, "arithmetic overflow"); |
| return nullptr; |
| } |
| return RESULT(/); |
| case Operator::Kind::PERCENT: |
| if (leftVal == std::numeric_limits<SKSL_INT>::min() && rightVal == -1) { |
| context.fErrors->error(pos, "arithmetic overflow"); |
| return nullptr; |
| } |
| return RESULT(%); |
| case Operator::Kind::BITWISEAND: return RESULT(&); |
| case Operator::Kind::BITWISEOR: return RESULT(|); |
| case Operator::Kind::BITWISEXOR: return RESULT(^); |
| case Operator::Kind::EQEQ: return RESULT(==); |
| case Operator::Kind::NEQ: return RESULT(!=); |
| case Operator::Kind::GT: return RESULT(>); |
| case Operator::Kind::GTEQ: return RESULT(>=); |
| case Operator::Kind::LT: return RESULT(<); |
| case Operator::Kind::LTEQ: return RESULT(<=); |
| case Operator::Kind::SHL: |
| if (rightVal >= 0 && rightVal <= 31) { |
| // Left-shifting a negative (or really, any signed) value is undefined behavior |
| // in C++, but not GLSL. Do the shift on unsigned values, to avoid UBSAN. |
| return URESULT(<<); |
| } |
| context.fErrors->error(pos, "shift value out of range"); |
| return nullptr; |
| case Operator::Kind::SHR: |
| if (rightVal >= 0 && rightVal <= 31) { |
| return RESULT(>>); |
| } |
| context.fErrors->error(pos, "shift value out of range"); |
| return nullptr; |
| |
| default: |
| return nullptr; |
| } |
| #undef RESULT |
| #undef URESULT |
| } |
| |
| // Perform constant folding on pairs of floating-point literals. |
| if (left->isFloatLiteral() && right->isFloatLiteral()) { |
| SKSL_FLOAT leftVal = left->as<Literal>().floatValue(); |
| SKSL_FLOAT rightVal = right->as<Literal>().floatValue(); |
| |
| #define RESULT(Op) fold_float_expression(pos, leftVal Op rightVal, &resultType) |
| switch (op.kind()) { |
| case Operator::Kind::PLUS: return RESULT(+); |
| case Operator::Kind::MINUS: return RESULT(-); |
| case Operator::Kind::STAR: return RESULT(*); |
| case Operator::Kind::SLASH: return RESULT(/); |
| case Operator::Kind::EQEQ: return RESULT(==); |
| case Operator::Kind::NEQ: return RESULT(!=); |
| case Operator::Kind::GT: return RESULT(>); |
| case Operator::Kind::GTEQ: return RESULT(>=); |
| case Operator::Kind::LT: return RESULT(<); |
| case Operator::Kind::LTEQ: return RESULT(<=); |
| default: return nullptr; |
| } |
| #undef RESULT |
| } |
| |
| // Perform matrix multiplication. |
| if (op.kind() == Operator::Kind::STAR) { |
| if (leftType.isMatrix() && rightType.isMatrix()) { |
| return simplify_matrix_times_matrix(context, pos, *left, *right); |
| } |
| if (leftType.isVector() && rightType.isMatrix()) { |
| return simplify_vector_times_matrix(context, pos, *left, *right); |
| } |
| if (leftType.isMatrix() && rightType.isVector()) { |
| return simplify_matrix_times_vector(context, pos, *left, *right); |
| } |
| } |
| |
| // Perform constant folding on pairs of vectors/matrices. |
| if (is_vec_or_mat(leftType) && leftType.matches(rightType)) { |
| return simplify_componentwise(context, pos, *left, op, *right); |
| } |
| |
| // Perform constant folding on vectors/matrices against scalars, e.g.: half4(2) + 2 |
| if (rightType.isScalar() && is_vec_or_mat(leftType) && |
| leftType.componentType().matches(rightType)) { |
| return simplify_componentwise(context, pos, *left, op, |
| *splat_scalar(context, *right, left->type())); |
| } |
| |
| // Perform constant folding on scalars against vectors/matrices, e.g.: 2 + half4(2) |
| if (leftType.isScalar() && is_vec_or_mat(rightType) && |
| rightType.componentType().matches(leftType)) { |
| return simplify_componentwise(context, pos, *splat_scalar(context, *left, right->type()), |
| op, *right); |
| } |
| |
| // Perform constant folding on pairs of matrices, arrays or structs. |
| if ((leftType.isMatrix() && rightType.isMatrix()) || |
| (leftType.isArray() && rightType.isArray()) || |
| (leftType.isStruct() && rightType.isStruct())) { |
| return simplify_constant_equality(context, pos, *left, op, *right); |
| } |
| |
| // We aren't able to constant-fold. |
| return nullptr; |
| } |
| |
| } // namespace SkSL |
