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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 "src/sksl/SkSLPosition.h"
- #include "src/sksl/ir/SkSLModifiers.h"
- #include "src/sksl/ir/SkSLSymbol.h"
- #include "src/sksl/ir/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,
- kInterfaceBlock_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 {
- if ((fStorage != kLocal_Storage && fReadCount) ||
- (fModifiers.fFlags & (Modifiers::kIn_Flag | Modifiers::kOut_Flag |
- Modifiers::kUniform_Flag))) {
- return false;
- }
- return !fWriteCount ||
- (!fReadCount && !(fModifiers.fFlags & (Modifiers::kPLS_Flag |
- Modifiers::kPLSOut_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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