| /* |
| * 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); |
| } |
| |
| 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 | Modifiers::kVarying_Flag))) { |
| return false; |
| } |
| return !fWriteCount || |
| (!fReadCount && !(fModifiers.fFlags & (Modifiers::kPLS_Flag | |
| Modifiers::kPLSOut_Flag))); |
| } |
| |
| mutable Modifiers fModifiers; |
| const Type& fType; |
| const Storage fStorage; |
| |
| const 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 |