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/*
* Copyright 2016 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SKSL_VARIABLE
#define SKSL_VARIABLE
#include "SkSLModifiers.h"
#include "SkSLPosition.h"
#include "SkSLSymbol.h"
#include "SkSLType.h"
namespace SkSL {
struct Expression;
/**
* Represents a variable, whether local, global, or a function parameter. This represents the
* variable itself (the storage location), which is shared between all VariableReferences which
* read or write that storage location.
*/
struct Variable : public Symbol {
enum Storage {
kGlobal_Storage,
kLocal_Storage,
kParameter_Storage
};
Variable(int offset, Modifiers modifiers, StringFragment name, const Type& type,
Storage storage, Expression* initialValue = nullptr)
: INHERITED(offset, kVariable_Kind, name)
, fModifiers(modifiers)
, fType(type)
, fStorage(storage)
, fInitialValue(initialValue)
, fReadCount(0)
, fWriteCount(initialValue ? 1 : 0) {}
~Variable() override {
// can't destroy a variable while there are remaining references to it
if (fInitialValue) {
--fWriteCount;
}
SkASSERT(!fReadCount && !fWriteCount);
}
virtual String description() const override {
return fModifiers.description() + fType.fName + " " + fName;
}
bool dead() const {
return !fWriteCount || (!fReadCount && !(fModifiers.fFlags & Modifiers::kOut_Flag));
}
mutable Modifiers fModifiers;
const Type& fType;
const Storage fStorage;
Expression* fInitialValue = nullptr;
// Tracks how many sites read from the variable. If this is zero for a non-out variable (or
// becomes zero during optimization), the variable is dead and may be eliminated.
mutable int fReadCount;
// Tracks how many sites write to the variable. If this is zero, the variable is dead and may be
// eliminated.
mutable int fWriteCount;
typedef Symbol INHERITED;
};
} // namespace SkSL
#endif
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