Halide
Closure.h
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1 #ifndef HALIDE_CLOSURE_H
2 #define HALIDE_CLOSURE_H
3 
4 /** \file
5  *
6  * Provides Closure class.
7  */
8 #include <map>
9 #include <string>
10 
11 #include "Buffer.h"
12 #include "IR.h"
13 #include "IRVisitor.h"
14 #include "Scope.h"
15 
16 namespace Halide {
17 
18 namespace Internal {
19 
20 /** A helper class to manage closures. Walks over a statement and
21  * retrieves all the references within it to external symbols
22  * (variables and allocations). It then helps you build a struct
23  * containing the current values of these symbols that you can use as
24  * a closure if you want to migrate the body of the statement to its
25  * own function (e.g. because it's the body of a parallel for loop. */
26 class Closure : public IRVisitor {
27 protected:
29 
30  using IRVisitor::visit;
31 
32  void visit(const Let *op) override;
33  void visit(const LetStmt *op) override;
34  void visit(const For *op) override;
35  void visit(const Load *op) override;
36  void visit(const Store *op) override;
37  void visit(const Allocate *op) override;
38  void visit(const Variable *op) override;
39  void visit(const Atomic *op) override;
40 
41 public:
42  /** Information about a buffer reference from a closure. */
43  struct Buffer {
44  /** The type of the buffer referenced. */
46 
47  /** The dimensionality of the buffer. */
49 
50  /** The buffer is read from. */
51  bool read = false;
52 
53  /** The buffer is written to. */
54  bool write = false;
55 
56  /** The buffer is a texture */
58 
59  /** The size of the buffer if known, otherwise zero. */
60  size_t size = 0;
61 
62  Buffer() = default;
63  };
64 
65 protected:
66  void found_buffer_ref(const std::string &name, Type type,
67  bool read, bool written, const Halide::Buffer<> &image);
68 
69 public:
70  Closure() = default;
71 
72  // Movable but not copyable.
73  Closure(const Closure &) = delete;
74  Closure &operator=(const Closure &) = delete;
75  Closure(Closure &&) = default;
76  Closure &operator=(Closure &&) = default;
77 
78  /** Traverse a statement and find all references to external
79  * symbols.
80  *
81  * When the closure encounters a read or write to 'foo', it
82  * assumes that the host pointer is found in the symbol table as
83  * 'foo.host', and any halide_buffer_t pointer is found under
84  * 'foo.buffer'.
85  *
86  * Calling this multiple times (on multiple statements) is legal
87  * (and will produce a unified closure).
88  **/
89  void include(const Stmt &s, const std::string &loop_variable = "");
90 
91  /** External variables referenced. There's code that assumes iterating over
92  * this repeatedly gives a consistent order, so don't swap out the data type
93  * for something non-deterministic. */
94  std::map<std::string, Type> vars;
95 
96  /** External allocations referenced. */
97  std::map<std::string, Buffer> buffers;
98 
99  /** Pack a closure into a struct. */
100  Expr pack_into_struct() const;
101 
102  /** Unpack a closure around a Stmt, putting all the names in scope. */
103  Stmt unpack_from_struct(const Expr &, const Stmt &) const;
104 };
105 
106 } // namespace Internal
107 } // namespace Halide
108 
109 #endif
Halide::Internal::Closure::ignore
Scope ignore
Definition: Closure.h:28
Halide::Internal::Allocate
Allocate a scratch area called with the given name, type, and size.
Definition: IR.h:363
Scope.h
Halide::Internal::IRVisitor::visit
virtual void visit(const IntImm *)
uint8_t
unsigned __INT8_TYPE__ uint8_t
Definition: runtime_internal.h:29
Halide::Internal::Closure::pack_into_struct
Expr pack_into_struct() const
Pack a closure into a struct.
Halide::Internal::Closure::Buffer::memory_type
MemoryType memory_type
The buffer is a texture.
Definition: Closure.h:57
Halide::Internal::IRVisitor
A base class for algorithms that need to recursively walk over the IR.
Definition: IRVisitor.h:19
Halide::Internal::For
A for loop.
Definition: IR.h:788
Halide::Internal::Closure::include
void include(const Stmt &s, const std::string &loop_variable="")
Traverse a statement and find all references to external symbols.
Halide::Internal::Closure::found_buffer_ref
void found_buffer_ref(const std::string &name, Type type, bool read, bool written, const Halide::Buffer<> &image)
Halide::Internal::LetStmt
The statement form of a let node.
Definition: IR.h:274
Halide::Internal::Closure::operator=
Closure & operator=(const Closure &)=delete
Halide::Internal::Scope
A common pattern when traversing Halide IR is that you need to keep track of stuff when you find a Le...
Definition: ModulusRemainder.h:17
IR.h
Halide::Internal::Stmt
A reference-counted handle to a statement node.
Definition: Expr.h:418
Halide::Internal::Closure::Buffer::write
bool write
The buffer is written to.
Definition: Closure.h:54
Halide::Type
Types in the halide type system.
Definition: Type.h:276
Halide::Internal::Closure::unpack_from_struct
Stmt unpack_from_struct(const Expr &, const Stmt &) const
Unpack a closure around a Stmt, putting all the names in scope.
Halide::Internal::Load
Load a value from a named symbol if predicate is true.
Definition: IR.h:209
Halide
This file defines the class FunctionDAG, which is our representation of a Halide pipeline,...
Definition: AbstractGenerator.h:19
Halide::Internal::Closure::buffers
std::map< std::string, Buffer > buffers
External allocations referenced.
Definition: Closure.h:97
Halide::Internal::Closure::visit
void visit(const Let *op) override
Halide::Internal::Closure::Buffer::type
Type type
The type of the buffer referenced.
Definition: Closure.h:45
Halide::Internal::Closure::Buffer
Information about a buffer reference from a closure.
Definition: Closure.h:43
Halide::Internal::Closure::vars
std::map< std::string, Type > vars
External variables referenced.
Definition: Closure.h:94
Halide::LinkageType::Internal
@ Internal
Not visible externally, similar to 'static' linkage in C.
Halide::Internal::Closure::Closure
Closure()=default
Halide::Buffer<>
Halide::Internal::Let
A let expression, like you might find in a functional language.
Definition: IR.h:263
Buffer.h
IRVisitor.h
Halide::Internal::Closure::Buffer::size
size_t size
The size of the buffer if known, otherwise zero.
Definition: Closure.h:60
Halide::Internal::Closure::Buffer::dimensions
uint8_t dimensions
The dimensionality of the buffer.
Definition: Closure.h:48
Halide::Internal::Store
Store a 'value' to the buffer called 'name' at a given 'index' if 'predicate' is true.
Definition: IR.h:325
Halide::Internal::Variable
A named variable.
Definition: IR.h:741
Halide::Internal::Closure
A helper class to manage closures.
Definition: Closure.h:26
Halide::Internal::Closure::Buffer::read
bool read
The buffer is read from.
Definition: Closure.h:51
Halide::MemoryType::Auto
@ Auto
Let Halide select a storage type automatically.
Halide::Expr
A fragment of Halide syntax.
Definition: Expr.h:257
Halide::MemoryType
MemoryType
An enum describing different address spaces to be used with Func::store_in.
Definition: Expr.h:347
Halide::Internal::Atomic
Lock all the Store nodes in the body statement.
Definition: IR.h:911
Halide::Internal::Closure::Buffer::Buffer
Buffer()=default