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* Copyright 2020 Google LLC
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
#ifndef SkSLAnalysis_DEFINED
#define SkSLAnalysis_DEFINED
#include "include/private/SkSLSampleUsage.h"
#include "src/sksl/SkSLDefines.h"
#include <memory>
namespace SkSL {
class ErrorReporter;
class Expression;
class FunctionDeclaration;
class FunctionDefinition;
struct LoadedModule;
struct Program;
class ProgramElement;
class ProgramUsage;
class Statement;
class Variable;
class VariableReference;
* Provides utilities for analyzing SkSL statically before it's composed into a full program.
struct Analysis {
static SampleUsage GetSampleUsage(const Program& program, const Variable& fp);
static bool ReferencesBuiltin(const Program& program, int builtin);
static bool ReferencesSampleCoords(const Program& program);
static bool ReferencesFragCoords(const Program& program);
static bool NodeCountExceeds(const FunctionDefinition& function, int limit);
static std::unique_ptr<ProgramUsage> GetUsage(const Program& program);
static std::unique_ptr<ProgramUsage> GetUsage(const LoadedModule& module);
static bool StatementWritesToVariable(const Statement& stmt, const Variable& var);
static bool IsAssignable(Expression& expr, VariableReference** assignableVar,
ErrorReporter* errors = nullptr);
// A "trivial" expression is one where we'd feel comfortable cloning it multiple times in
// the code, without worrying about incurring a performance penalty. Examples:
// - true
// - 3.14159265
// - myIntVariable
// - myColor.rgb
// - myArray[123]
// - myStruct.myField
// - half4(0)
// Trivial-ness is stackable. Somewhat large expressions can occasionally make the cut:
// - half4(myColor.a)
// - myStruct.myArrayField[7].xyz
static bool IsTrivialExpression(const Expression& expr);
* Utility class to visit every element, statement, and expression in an SkSL program IR.
* This is intended for simple analysis and accumulation, where custom visitation behavior is only
* needed for a limited set of expression kinds.
* Subclasses should override visitExpression/visitStatement/visitProgramElement as needed and
* intercept elements of interest. They can then invoke the base class's function to visit all
* sub expressions. They can also choose not to call the base function to arrest recursion, or
* implement custom recursion.
* The visit functions return a bool that determines how the default implementation recurses. Once
* any visit call returns true, the default behavior stops recursing and propagates true up the
* stack.
template <typename PROG, typename EXPR, typename STMT, typename ELEM>
class TProgramVisitor {
virtual ~TProgramVisitor() = default;
virtual bool visitExpression(EXPR expression);
virtual bool visitStatement(STMT statement);
virtual bool visitProgramElement(ELEM programElement);
// Squelch bogus Clang warning about template vtables:
#if defined(__clang__)
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wweak-template-vtables"
extern template class TProgramVisitor<const Program&, const Expression&,
const Statement&, const ProgramElement&>;
extern template class TProgramVisitor<Program&, Expression&, Statement&, ProgramElement&>;
#if defined(__clang__)
#pragma clang diagnostic pop
class ProgramVisitor : public TProgramVisitor<const Program&,
const Expression&,
const Statement&,
const ProgramElement&> {
bool visit(const Program& program);
using ProgramWriter = TProgramVisitor<Program&, Expression&, Statement&, ProgramElement&>;
} // namespace SkSL