1 /* 2 * Copyright 2020 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 #ifndef SKSL_CONSTANT_FOLDER 9 #define SKSL_CONSTANT_FOLDER 10 11 #include <memory> 12 13 #include "include/private/SkSLDefines.h" 14 #include "src/sksl/SkSLOperators.h" 15 16 namespace SkSL { 17 18 class Context; 19 class ErrorReporter; 20 class Expression; 21 22 /** 23 * Performs constant folding on IR expressions. This simplifies expressions containing 24 * compile-time constants, such as replacing `IntLiteral(2) + IntLiteral(2)` with `IntLiteral(4)`. 25 */ 26 class ConstantFolder { 27 public: 28 /** 29 * If value is an int literal or const int variable with a known value, returns true and stores 30 * the value in out. Otherwise returns false. 31 */ 32 static bool GetConstantInt(const Expression& value, SKSL_INT* out); 33 34 /** 35 * If value is a float literal or const float variable with a known value, returns true and 36 * stores the value in out. Otherwise returns false. 37 */ 38 static bool GetConstantFloat(const Expression& value, SKSL_FLOAT* out); 39 40 /** 41 * If the expression is a const variable with a known compile-time-constant value, returns that 42 * value. If not, returns the original expression as-is. 43 */ 44 static const Expression* GetConstantValueForVariable(const Expression& value); 45 46 /** 47 * If the expression is a const variable with a known compile-time-constant value, returns a 48 * clone of that value. If not, returns the original expression as-is. 49 */ 50 static std::unique_ptr<Expression> MakeConstantValueForVariable( 51 std::unique_ptr<Expression> expr); 52 53 /** 54 * Reports an error and returns true if op is a division / mod operator and right is zero or 55 * contains a zero element. 56 */ 57 static bool ErrorOnDivideByZero(const Context& context, int offset, Operator op, 58 const Expression& right); 59 60 /** Simplifies the binary expression `left OP right`. Returns null if it can't be simplified. */ 61 static std::unique_ptr<Expression> Simplify(const Context& context, 62 int offset, 63 const Expression& left, 64 Operator op, 65 const Expression& right, 66 const Type& resultType); 67 }; 68 69 } // namespace SkSL 70 71 #endif // SKSL_CONSTANT_FOLDER 72