1 /*
2  * Copyright 2016 Google Inc.
3  *
4  * Use of this source code is governed by a BSD-style license that can be
5  * found in the LICENSE file.
6  */
7 
8 #ifndef SKSL_VARIABLE
9 #define SKSL_VARIABLE
10 
11 #include "SkSLModifiers.h"
12 #include "SkSLPosition.h"
13 #include "SkSLSymbol.h"
14 #include "SkSLType.h"
15 
16 namespace SkSL {
17 
18 /**
19  * Represents a variable, whether local, global, or a function parameter. This represents the
20  * variable itself (the storage location), which is shared between all VariableReferences which
21  * read or write that storage location.
22  */
23 struct Variable : public Symbol {
24     enum Storage {
25         kGlobal_Storage,
26         kLocal_Storage,
27         kParameter_Storage
28     };
29 
VariableVariable30     Variable(Position position, Modifiers modifiers, SkString name, const Type& type,
31              Storage storage)
32     : INHERITED(position, kVariable_Kind, std::move(name))
33     , fModifiers(modifiers)
34     , fType(type)
35     , fStorage(storage)
36     , fReadCount(0)
37     , fWriteCount(0) {}
38 
descriptionVariable39     virtual SkString description() const override {
40         return fModifiers.description() + fType.fName + " " + fName;
41     }
42 
43     mutable Modifiers fModifiers;
44     const Type& fType;
45     const Storage fStorage;
46 
47     // Tracks how many sites read from the variable. If this is zero for a non-out variable (or
48     // becomes zero during optimization), the variable is dead and may be eliminated.
49     mutable int fReadCount;
50     // Tracks how many sites write to the variable. If this is zero, the variable is dead and may be
51     // eliminated.
52     mutable int fWriteCount;
53 
54     typedef Symbol INHERITED;
55 };
56 
57 } // namespace SkSL
58 
59 #endif
60