src/compiler/translator/SymbolTable.h

//
// Copyright (c) 2002-2014 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//

#ifndef COMPILER_TRANSLATOR_SYMBOLTABLE_H_
#define COMPILER_TRANSLATOR_SYMBOLTABLE_H_

//
// Symbol table for parsing.  Has these design characteristics:
//
// * Same symbol table can be used to compile many shaders, to preserve
//   effort of creating and loading with the large numbers of built-in
//   symbols.
//
// * Name mangling will be used to give each function a unique name
//   so that symbol table lookups are never ambiguous.  This allows
//   a simpler symbol table structure.
//
// * Pushing and popping of scope, so symbol table will really be a stack
//   of symbol tables.  Searched from the top, with new inserts going into
//   the top.
//
// * Constants:  Compile time constant symbols will keep their values
//   in the symbol table.  The parser can substitute constants at parse
//   time, including doing constant folding and constant propagation.
//
// * No temporaries:  Temporaries made from operations (+, --, .xy, etc.)
//   are tracked in the intermediate representation, not the symbol table.
//

#include <array>
#include <assert.h>
#include <set>

#include "common/angleutils.h"
#include "compiler/translator/ExtensionBehavior.h"
#include "compiler/translator/ImmutableString.h"
#include "compiler/translator/InfoSink.h"
#include "compiler/translator/IntermNode.h"
#include "compiler/translator/StaticType.h"
#include "compiler/translator/Symbol.h"

namespace sh
{

// Define ESymbolLevel as int rather than an enum since level can go
// above GLOBAL_LEVEL and cause atBuiltInLevel() to fail if the
// compiler optimizes the >= of the last element to ==.
typedef int ESymbolLevel;
const int COMMON_BUILTINS    = 0;
const int ESSL1_BUILTINS     = 1;
const int ESSL3_BUILTINS     = 2;
const int ESSL3_1_BUILTINS   = 3;
// GLSL_BUILTINS are desktop GLSL builtins that don't exist in ESSL but are used to implement
// features in ANGLE's GLSL backend. They're not visible to the parser.
const int GLSL_BUILTINS      = 4;
const int LAST_BUILTIN_LEVEL = GLSL_BUILTINS;
const int GLOBAL_LEVEL       = 5;

class TSymbolTable : angle::NonCopyable
{
  public:
    TSymbolTable() : mUniqueIdCounter(0), mUserDefinedUniqueIdsStart(-1)
    {
        // The symbol table cannot be used until push() is called, but
        // the lack of an initial call to push() can be used to detect
        // that the symbol table has not been preloaded with built-ins.
    }

    ~TSymbolTable();

    // When the symbol table is initialized with the built-ins, there should
    // 'push' calls, so that built-ins are at level 0 and the shader
    // globals are at level 1.
    bool isEmpty() const { return table.empty(); }
    bool atBuiltInLevel() const { return currentLevel() <= LAST_BUILTIN_LEVEL; }
    bool atGlobalLevel() const { return currentLevel() == GLOBAL_LEVEL; }

    void push();
    void pop();

    // The declare* entry points are used when parsing and declare symbols at the current scope.
    // They return the created true in case the declaration was successful, and false if the
    // declaration failed due to redefinition.
    bool declareVariable(TVariable *variable);
    bool declareStructType(TStructure *str);
    bool declareInterfaceBlock(TInterfaceBlock *interfaceBlock);
    // Functions are always declared at global scope.
    void declareUserDefinedFunction(TFunction *function, bool insertUnmangledName);

    // These return the TFunction pointer to keep using to refer to this function.
    const TFunction *markUserDefinedFunctionHasPrototypeDeclaration(
        const ImmutableString &mangledName,
        bool *hadPrototypeDeclarationOut);
    const TFunction *setUserDefinedFunctionParameterNamesFromDefinition(const TFunction *function,
                                                                        bool *wasDefinedOut);

    // find() is guaranteed not to retain a reference to the ImmutableString, so an ImmutableString
    // with a reference to a short-lived char * is fine to pass here.
    const TSymbol *find(const ImmutableString &name, int shaderVersion) const;

    const TSymbol *findGlobal(const ImmutableString &name) const;

    const TSymbol *findBuiltIn(const ImmutableString &name, int shaderVersion) const;

    const TSymbol *findBuiltIn(const ImmutableString &name,
                               int shaderVersion,
                               bool includeGLSLBuiltins) const;

    void setDefaultPrecision(TBasicType type, TPrecision prec)
    {
        int indexOfLastElement = static_cast<int>(precisionStack.size()) - 1;
        // Uses map operator [], overwrites the current value
        (*precisionStack[indexOfLastElement])[type] = prec;
    }

    // Searches down the precisionStack for a precision qualifier
    // for the specified TBasicType
    TPrecision getDefaultPrecision(TBasicType type) const;

    // This records invariant varyings declared through
    // "invariant varying_name;".
    void addInvariantVarying(const std::string &originalName);

    // If this returns false, the varying could still be invariant
    // if it is set as invariant during the varying variable
    // declaration - this piece of information is stored in the
    // variable's type, not here.
    bool isVaryingInvariant(const std::string &originalName) const;

    void setGlobalInvariant(bool invariant);

    const TSymbolUniqueId nextUniqueId() { return TSymbolUniqueId(this); }

    // Checks whether there is a built-in accessible by a shader with the specified version.
    bool hasUnmangledBuiltInForShaderVersion(const char *name, int shaderVersion);

    void initializeBuiltIns(sh::GLenum type,
                            ShShaderSpec spec,
                            const ShBuiltInResources &resources);
    void clearCompilationResults();

  private:
    friend class TSymbolUniqueId;
    int nextUniqueIdValue();

    class TSymbolTableLevel;

    ESymbolLevel currentLevel() const { return static_cast<ESymbolLevel>(table.size() - 1); }

    // The insert* entry points are used when initializing the symbol table with built-ins.
    // They return the created symbol / true in case the declaration was successful, and nullptr /
    // false if the declaration failed due to redefinition.
    TVariable *insertVariable(ESymbolLevel level, const ImmutableString &name, const TType *type);
    TVariable *insertVariableExt(ESymbolLevel level,
                                 TExtension ext,
                                 const ImmutableString &name,
                                 const TType *type);
    bool insertVariable(ESymbolLevel level, TVariable *variable);
    bool insertStructType(ESymbolLevel level, TStructure *str);
    bool insertInterfaceBlock(ESymbolLevel level, TInterfaceBlock *interfaceBlock);

    template <TPrecision precision>
    bool insertConstInt(ESymbolLevel level, const ImmutableString &name, int value);

    template <TPrecision precision>
    bool insertConstIntExt(ESymbolLevel level,
                           TExtension ext,
                           const ImmutableString &name,
                           int value);

    template <TPrecision precision>
    bool insertConstIvec3(ESymbolLevel level,
                          const ImmutableString &name,
                          const std::array<int, 3> &values);

    // Note that for inserted built-in functions the const char *name needs to remain valid for the
    // lifetime of the SymbolTable. SymbolTable does not allocate a copy of it.
    void insertBuiltIn(ESymbolLevel level,
                       TOperator op,
                       TExtension ext,
                       const TType *rvalue,
                       const char *name,
                       const TType *ptype1,
                       const TType *ptype2 = 0,
                       const TType *ptype3 = 0,
                       const TType *ptype4 = 0,
                       const TType *ptype5 = 0);

    void insertBuiltIn(ESymbolLevel level,
                       const TType *rvalue,
                       const char *name,
                       const TType *ptype1,
                       const TType *ptype2 = 0,
                       const TType *ptype3 = 0,
                       const TType *ptype4 = 0,
                       const TType *ptype5 = 0)
    {
        insertUnmangledBuiltInName(name, level);
        insertBuiltIn(level, EOpNull, TExtension::UNDEFINED, rvalue, name, ptype1, ptype2, ptype3,
                      ptype4, ptype5);
    }

    void insertBuiltIn(ESymbolLevel level,
                       TExtension ext,
                       const TType *rvalue,
                       const char *name,
                       const TType *ptype1,
                       const TType *ptype2 = 0,
                       const TType *ptype3 = 0,
                       const TType *ptype4 = 0,
                       const TType *ptype5 = 0)
    {
        insertUnmangledBuiltInName(name, level);
        insertBuiltIn(level, EOpNull, ext, rvalue, name, ptype1, ptype2, ptype3, ptype4, ptype5);
    }

    void insertBuiltInOp(ESymbolLevel level,
                         TOperator op,
                         const TType *rvalue,
                         const TType *ptype1,
                         const TType *ptype2 = 0,
                         const TType *ptype3 = 0,
                         const TType *ptype4 = 0,
                         const TType *ptype5 = 0);

    void insertBuiltInOp(ESymbolLevel level,
                         TOperator op,
                         TExtension ext,
                         const TType *rvalue,
                         const TType *ptype1,
                         const TType *ptype2 = 0,
                         const TType *ptype3 = 0,
                         const TType *ptype4 = 0,
                         const TType *ptype5 = 0);

    void insertBuiltInFunctionNoParameters(ESymbolLevel level,
                                           TOperator op,
                                           const TType *rvalue,
                                           const char *name);

    void insertBuiltInFunctionNoParametersExt(ESymbolLevel level,
                                              TExtension ext,
                                              TOperator op,
                                              const TType *rvalue,
                                              const char *name);

    TVariable *insertVariable(ESymbolLevel level,
                              const ImmutableString &name,
                              const TType *type,
                              SymbolType symbolType);

    bool insert(ESymbolLevel level, TSymbol *symbol);

    TFunction *findUserDefinedFunction(const ImmutableString &name) const;

    // Used to insert unmangled functions to check redeclaration of built-ins in ESSL 3.00 and
    // above.
    void insertUnmangledBuiltInName(const char *name, ESymbolLevel level);

    bool hasUnmangledBuiltInAtLevel(const char *name, ESymbolLevel level);

    void initSamplerDefaultPrecision(TBasicType samplerType);

    void initializeBuiltInFunctions(sh::GLenum type,
                                    ShShaderSpec spec,
                                    const ShBuiltInResources &resources);
    void initializeBuiltInVariables(sh::GLenum type,
                                    ShShaderSpec spec,
                                    const ShBuiltInResources &resources);
    void markBuiltInInitializationFinished();

    std::vector<TSymbolTableLevel *> table;
    typedef TMap<TBasicType, TPrecision> PrecisionStackLevel;
    std::vector<PrecisionStackLevel *> precisionStack;

    int mUniqueIdCounter;

    // -1 before built-in init has finished, one past the last built-in id afterwards.
    // TODO(oetuaho): Make this a compile-time constant once the symbol table is initialized at
    // compile time. http://anglebug.com/1432
    int mUserDefinedUniqueIdsStart;
};

}  // namespace sh

#endif  // COMPILER_TRANSLATOR_SYMBOLTABLE_H_