Halide  19.0.0
Halide compiler and libraries
Function.h
Go to the documentation of this file.
1 #ifndef HALIDE_FUNCTION_H
2 #define HALIDE_FUNCTION_H
3 
4 /** \file
5  * Defines the internal representation of a halide function and related classes
6  */
7 #include <map>
8 #include <string>
9 #include <utility>
10 #include <vector>
11 
12 #include "Definition.h"
13 #include "Expr.h"
14 #include "FunctionPtr.h"
15 #include "Reduction.h"
16 #include "Schedule.h"
17 
18 namespace Halide {
19 
20 struct ExternFuncArgument;
21 class Parameter;
22 class Tuple;
23 class Var;
24 
25 /** An enum to specify calling convention for extern stages. */
26 enum class NameMangling {
27  Default, ///< Match whatever is specified in the Target
28  C, ///< No name mangling
29  CPlusPlus, ///< C++ name mangling
30 };
31 
32 namespace Internal {
33 
34 struct Call;
35 
36 /** A reference-counted handle to Halide's internal representation of
37  * a function. Similar to a front-end Func object, but with no
38  * syntactic sugar to help with definitions. */
39 class Function {
40  FunctionPtr contents;
41 
42 public:
43  /** This lets you use a Function as a key in a map of the form
44  * map<Function, Foo, Function::Compare> */
45  struct Compare {
46  bool operator()(const Function &a, const Function &b) const {
47  internal_assert(a.contents.defined() && b.contents.defined());
48  return a.contents < b.contents;
49  }
50  };
51 
52  /** Construct a new function with no definitions and no name. This
53  * constructor only exists so that you can make vectors of
54  * functions, etc.
55  */
56  Function() = default;
57 
58  /** Construct a new function with the given name */
59  explicit Function(const std::string &n);
60 
61  /** Construct a new function with the given name,
62  * with a requirement that it can only represent Expr(s) of the given type(s),
63  * and must have exactly the give nnumber of dimensions.
64  * required_types.empty() means there are no constraints on the type(s).
65  * required_dims == AnyDims means there are no constraints on the dimensions. */
66  explicit Function(const std::vector<Type> &required_types, int required_dims, const std::string &n);
67 
68  /** Construct a Function from an existing FunctionContents pointer. Must be non-null */
69  explicit Function(const FunctionPtr &);
70 
71  /** Update a function with deserialized data */
72  void update_with_deserialization(const std::string &name,
73  const std::string &origin_name,
74  const std::vector<Halide::Type> &output_types,
75  const std::vector<Halide::Type> &required_types,
76  int required_dims,
77  const std::vector<std::string> &args,
78  const FuncSchedule &func_schedule,
79  const Definition &init_def,
80  const std::vector<Definition> &updates,
81  const std::string &debug_file,
82  const std::vector<Parameter> &output_buffers,
83  const std::vector<ExternFuncArgument> &extern_arguments,
84  const std::string &extern_function_name,
85  NameMangling name_mangling,
86  DeviceAPI device_api,
87  const Expr &extern_proxy_expr,
88  bool trace_loads,
89  bool trace_stores,
90  bool trace_realizations,
91  const std::vector<std::string> &trace_tags,
92  bool no_profiling,
93  bool frozen);
94 
95  /** Get a handle on the halide function contents that this Function
96  * represents. */
98  return contents;
99  }
100 
101  /** Deep copy this Function into 'copy'. It recursively deep copies all called
102  * functions, schedules, update definitions, extern func arguments, specializations,
103  * and reduction domains. This method does not deep-copy the Parameter objects.
104  * This method also takes a map of <old Function, deep-copied version> as input
105  * and would use the deep-copied Function from the map if exists instead of
106  * creating a new deep-copy to avoid creating deep-copies of the same Function
107  * multiple times. If 'name' is specified, copy's name will be set to that.
108  */
109  // @{
110  void deep_copy(const FunctionPtr &copy, std::map<FunctionPtr, FunctionPtr> &copied_map) const;
111  void deep_copy(std::string name, const FunctionPtr &copy,
112  std::map<FunctionPtr, FunctionPtr> &copied_map) const;
113  // @}
114 
115  /** Add a pure definition to this function. It may not already
116  * have a definition. All the free variables in 'value' must
117  * appear in the args list. 'value' must not depend on any
118  * reduction domain */
119  void define(const std::vector<std::string> &args, std::vector<Expr> values);
120 
121  /** Add an update definition to this function. It must already have a pure
122  * definition but not an update definition, and the length of args must
123  * match the length of args used in the pure definition. 'value' may depend
124  * on some reduction domain may contain variables from that domain as well
125  * as pure variables. A reduction domain may also be introduced by passing
126  * it as the last argument. Any pure variables must also appear as Variables
127  * in the args array, and they must have the same name as the pure
128  * definition's argument in the same index. */
129  void define_update(const std::vector<Expr> &args, std::vector<Expr> values, const ReductionDomain &rdom = ReductionDomain{});
130 
131  /** Accept a visitor to visit all of the definitions and arguments
132  * of this function. */
133  void accept(IRVisitor *visitor) const;
134 
135  /** Accept a mutator to mutator all of the definitions and
136  * arguments of this function. */
137  void mutate(IRMutator *mutator);
138 
139  /** Get the name of the function. */
140  const std::string &name() const;
141 
142  /** If this is a wrapper of another func, created by a chain of in
143  * or clone_in calls, returns the name of the original
144  * Func. Otherwise returns the name. */
145  const std::string &origin_name() const;
146 
147  /** Get a mutable handle to the init definition. */
149 
150  /** Get the init definition. */
151  const Definition &definition() const;
152 
153  /** Get the pure arguments. */
154  const std::vector<std::string> &args() const;
155 
156  /** Get the dimensionality. */
157  int dimensions() const;
158 
159  /** Get the number of outputs. */
160  int outputs() const;
161 
162  /** Get the types of the outputs. */
163  const std::vector<Type> &output_types() const;
164 
165  /** Get the type constaints on the outputs (if any). */
166  const std::vector<Type> &required_types() const;
167 
168  /** Get the dimensionality constaints on the outputs (if any). */
169  int required_dimensions() const;
170 
171  /** Get the right-hand-side of the pure definition. Returns an
172  * empty vector if there is no pure definition.
173  *
174  * Warning: Any Vars in the Exprs are not qualified with the Func name, so
175  * the Exprs may contain names which collide with names provided by
176  * unique_name.
177  */
178  const std::vector<Expr> &values() const;
179 
180  /** Does this function have a pure definition? */
181  bool has_pure_definition() const;
182 
183  /** Does this function *only* have a pure definition? */
184  bool is_pure() const {
185  return (has_pure_definition() &&
188  }
189 
190  /** Is it legal to inline this function? */
191  bool can_be_inlined() const;
192 
193  /** Get a handle to the function-specific schedule for the purpose
194  * of modifying it. */
196 
197  /** Get a const handle to the function-specific schedule for inspecting it. */
198  const FuncSchedule &schedule() const;
199 
200  /** Get a handle on the output buffer used for setting constraints
201  * on it. */
202  const std::vector<Parameter> &output_buffers() const;
203 
204  /** Get a mutable handle to the stage-specfic schedule for the update
205  * stage. */
207 
208  /** Get a mutable handle to this function's update definition at
209  * index 'idx'. */
210  Definition &update(int idx = 0);
211 
212  /** Get a const reference to this function's update definition at
213  * index 'idx'. */
214  const Definition &update(int idx = 0) const;
215 
216  /** Get a const reference to this function's update definitions. */
217  const std::vector<Definition> &updates() const;
218 
219  /** Does this function have an update definition? */
220  bool has_update_definition() const;
221 
222  /** Check if the function has an extern definition. */
223  bool has_extern_definition() const;
224 
225  /** Get the name mangling specified for the extern definition. */
227 
228  /** Make a call node to the extern definition. An error if the
229  * function has no extern definition. */
230  Expr make_call_to_extern_definition(const std::vector<Expr> &args,
231  const Target &t) const;
232 
233  /** Get the proxy Expr for the extern stage. This is an expression
234  * known to have the same data access pattern as the extern
235  * stage. It must touch at least all of the memory that the extern
236  * stage does, though it is permissible for it to be conservative
237  * and touch a superset. For most Functions, including those with
238  * extern definitions, this will be an undefined Expr. */
239  // @{
242  // @}
243 
244  /** Add an external definition of this Func. */
245  void define_extern(const std::string &function_name,
246  const std::vector<ExternFuncArgument> &args,
247  const std::vector<Type> &types,
248  const std::vector<Var> &dims,
249  NameMangling mangling, DeviceAPI device_api);
250 
251  /** Retrive the arguments of the extern definition. */
252  // @{
253  const std::vector<ExternFuncArgument> &extern_arguments() const;
254  std::vector<ExternFuncArgument> &extern_arguments();
255  // @}
256 
257  /** Get the name of the extern function called for an extern
258  * definition. */
259  const std::string &extern_function_name() const;
260 
261  /** Get the DeviceAPI declared for an extern function. */
263 
264  /** Test for equality of identity. */
265  bool same_as(const Function &other) const {
266  return contents.same_as(other.contents);
267  }
268 
269  /** Get a const handle to the debug filename. */
270  const std::string &debug_file() const;
271 
272  /** Get a handle to the debug filename. */
273  std::string &debug_file();
274 
275  /** Use an an extern argument to another function. */
276  operator ExternFuncArgument() const;
277 
278  /** Tracing calls and accessors, passed down from the Func
279  * equivalents. */
280  // @{
281  void trace_loads();
282  void trace_stores();
284  void add_trace_tag(const std::string &trace_tag);
285  bool is_tracing_loads() const;
286  bool is_tracing_stores() const;
288  const std::vector<std::string> &get_trace_tags() const;
289  // @}
290 
291  /** Replace this Function's LoopLevels with locked copies that
292  * cannot be mutated further. */
294 
295  /** Mark the function as too small for meaningful profiling. */
297 
298  /** Check if the function is marked as one that should not be profiled. */
299  bool should_not_profile() const;
300 
301  /** Mark function as frozen, which means it cannot accept new
302  * definitions. */
303  void freeze();
304 
305  /** Check if a function has been frozen. If so, it is an error to
306  * add new definitions. */
307  bool frozen() const;
308 
309  /** Make a new Function with the same lifetime as this one, and
310  * return a strong reference to it. Useful to create Functions which
311  * have circular references to this one - e.g. the wrappers
312  * produced by Func::in. */
313  Function new_function_in_same_group(const std::string &);
314 
315  /** Mark calls of this function by 'f' to be replaced with its wrapper
316  * during the lowering stage. If the string 'f' is empty, it means replace
317  * all calls to this function by all other functions (excluding itself) in
318  * the pipeline with the wrapper. This will also freeze 'wrapper' to prevent
319  * user from updating the values of the Function it wraps via the wrapper.
320  * See \ref Func::in for more details. */
321  // @{
322  void add_wrapper(const std::string &f, Function &wrapper);
323  const std::map<std::string, FunctionPtr> &wrappers() const;
324  // @}
325 
326  /** Check if a Function is a trivial wrapper around another
327  * Function, Buffer, or Parameter. Returns the Call node if it
328  * is. Otherwise returns null.
329  */
330  const Call *is_wrapper() const;
331 
332  /** Replace every call to Functions in 'substitutions' keys by all Exprs
333  * referenced in this Function to call to their substitute Functions (i.e.
334  * the corresponding values in 'substitutions' map). */
335  // @{
336  Function &substitute_calls(const std::map<FunctionPtr, FunctionPtr> &substitutions);
338  // @}
339 
340  /** Return true iff the name matches one of the Function's pure args. */
341  bool is_pure_arg(const std::string &name) const;
342 
343  /** If the Function has type requirements, check that the given argument
344  * is compatible with them. If not, assert-fail. (If there are no type requirements, do nothing.) */
345  void check_types(const Expr &e) const;
346  void check_types(const Tuple &t) const;
347  void check_types(const Type &t) const;
348  void check_types(const std::vector<Expr> &exprs) const;
349  void check_types(const std::vector<Type> &types) const;
350 
351  /** If the Function has dimension requirements, check that the given argument
352  * is compatible with them. If not, assert-fail. (If there are no dimension requirements, do nothing.) */
353  void check_dims(int dims) const;
354 
355  /** Define the output buffers. If the Function has types specified, this can be called at
356  * any time. If not, it can only be called for a Function with a pure definition. */
357  void create_output_buffers(const std::vector<Type> &types, int dims) const;
358 };
359 
360 /** Deep copy an entire Function DAG. */
361 std::pair<std::vector<Function>, std::map<std::string, Function>> deep_copy(
362  const std::vector<Function> &outputs,
363  const std::map<std::string, Function> &env);
364 
365 extern std::atomic<int> random_variable_counter;
366 
367 } // namespace Internal
368 } // namespace Halide
369 
370 #endif
Defines the internal representation of a halide function's definition and related classes.
#define internal_assert(c)
Definition: Errors.h:19
Base classes for Halide expressions (Halide::Expr) and statements (Halide::Internal::Stmt)
Defines internal classes related to Reduction Domains.
Defines the internal representation of the schedule for a function.
A Function definition which can either represent a init or an update definition.
Definition: Definition.h:38
A schedule for a Function of a Halide pipeline.
Definition: Schedule.h:590
A reference-counted handle to Halide's internal representation of a function.
Definition: Function.h:39
FunctionPtr get_contents() const
Get a handle on the halide function contents that this Function represents.
Definition: Function.h:97
std::string & debug_file()
Get a handle to the debug filename.
void define(const std::vector< std::string > &args, std::vector< Expr > values)
Add a pure definition to this function.
bool should_not_profile() const
Check if the function is marked as one that should not be profiled.
void deep_copy(const FunctionPtr &copy, std::map< FunctionPtr, FunctionPtr > &copied_map) const
Deep copy this Function into 'copy'.
bool frozen() const
Check if a function has been frozen.
DeviceAPI extern_function_device_api() const
Get the DeviceAPI declared for an extern function.
const std::vector< Definition > & updates() const
Get a const reference to this function's update definitions.
Function(const std::string &n)
Construct a new function with the given name.
int dimensions() const
Get the dimensionality.
void check_types(const Type &t) const
bool is_tracing_realizations() const
bool has_extern_definition() const
Check if the function has an extern definition.
int outputs() const
Get the number of outputs.
int required_dimensions() const
Get the dimensionality constaints on the outputs (if any).
void define_update(const std::vector< Expr > &args, std::vector< Expr > values, const ReductionDomain &rdom=ReductionDomain{})
Add an update definition to this function.
void lock_loop_levels()
Replace this Function's LoopLevels with locked copies that cannot be mutated further.
bool can_be_inlined() const
Is it legal to inline this function?
const std::vector< std::string > & get_trace_tags() const
std::vector< ExternFuncArgument > & extern_arguments()
const std::string & origin_name() const
If this is a wrapper of another func, created by a chain of in or clone_in calls, returns the name of...
bool is_tracing_stores() const
bool has_pure_definition() const
Does this function have a pure definition?
const std::string & extern_function_name() const
Get the name of the extern function called for an extern definition.
const std::string & debug_file() const
Get a const handle to the debug filename.
Function & substitute_calls(const std::map< FunctionPtr, FunctionPtr > &substitutions)
Replace every call to Functions in 'substitutions' keys by all Exprs referenced in this Function to c...
void check_dims(int dims) const
If the Function has dimension requirements, check that the given argument is compatible with them.
Function()=default
Construct a new function with no definitions and no name.
bool is_pure() const
Does this function only have a pure definition?
Definition: Function.h:184
Function & substitute_calls(const Function &orig, const Function &substitute)
bool has_update_definition() const
Does this function have an update definition?
void trace_loads()
Tracing calls and accessors, passed down from the Func equivalents.
const FuncSchedule & schedule() const
Get a const handle to the function-specific schedule for inspecting it.
Definition & update(int idx=0)
Get a mutable handle to this function's update definition at index 'idx'.
void update_with_deserialization(const std::string &name, const std::string &origin_name, const std::vector< Halide::Type > &output_types, const std::vector< Halide::Type > &required_types, int required_dims, const std::vector< std::string > &args, const FuncSchedule &func_schedule, const Definition &init_def, const std::vector< Definition > &updates, const std::string &debug_file, const std::vector< Parameter > &output_buffers, const std::vector< ExternFuncArgument > &extern_arguments, const std::string &extern_function_name, NameMangling name_mangling, DeviceAPI device_api, const Expr &extern_proxy_expr, bool trace_loads, bool trace_stores, bool trace_realizations, const std::vector< std::string > &trace_tags, bool no_profiling, bool frozen)
Update a function with deserialized data.
FuncSchedule & schedule()
Get a handle to the function-specific schedule for the purpose of modifying it.
const Definition & definition() const
Get the init definition.
Function new_function_in_same_group(const std::string &)
Make a new Function with the same lifetime as this one, and return a strong reference to it.
void check_types(const std::vector< Expr > &exprs) const
void create_output_buffers(const std::vector< Type > &types, int dims) const
Define the output buffers.
const std::vector< Expr > & values() const
Get the right-hand-side of the pure definition.
void mutate(IRMutator *mutator)
Accept a mutator to mutator all of the definitions and arguments of this function.
void define_extern(const std::string &function_name, const std::vector< ExternFuncArgument > &args, const std::vector< Type > &types, const std::vector< Var > &dims, NameMangling mangling, DeviceAPI device_api)
Add an external definition of this Func.
const Definition & update(int idx=0) const
Get a const reference to this function's update definition at index 'idx'.
void check_types(const Expr &e) const
If the Function has type requirements, check that the given argument is compatible with them.
void deep_copy(std::string name, const FunctionPtr &copy, std::map< FunctionPtr, FunctionPtr > &copied_map) const
NameMangling extern_definition_name_mangling() const
Get the name mangling specified for the extern definition.
void accept(IRVisitor *visitor) const
Accept a visitor to visit all of the definitions and arguments of this function.
bool same_as(const Function &other) const
Test for equality of identity.
Definition: Function.h:265
bool is_pure_arg(const std::string &name) const
Return true iff the name matches one of the Function's pure args.
const std::vector< Type > & output_types() const
Get the types of the outputs.
void check_types(const Tuple &t) const
void freeze()
Mark function as frozen, which means it cannot accept new definitions.
const Call * is_wrapper() const
Check if a Function is a trivial wrapper around another Function, Buffer, or Parameter.
Definition & definition()
Get a mutable handle to the init definition.
void do_not_profile()
Mark the function as too small for meaningful profiling.
void add_wrapper(const std::string &f, Function &wrapper)
Mark calls of this function by 'f' to be replaced with its wrapper during the lowering stage.
const std::vector< ExternFuncArgument > & extern_arguments() const
Retrive the arguments of the extern definition.
const std::vector< std::string > & args() const
Get the pure arguments.
const std::string & name() const
Get the name of the function.
void check_types(const std::vector< Type > &types) const
Expr make_call_to_extern_definition(const std::vector< Expr > &args, const Target &t) const
Make a call node to the extern definition.
Function(const FunctionPtr &)
Construct a Function from an existing FunctionContents pointer.
const std::vector< Type > & required_types() const
Get the type constaints on the outputs (if any).
const std::vector< Parameter > & output_buffers() const
Get a handle on the output buffer used for setting constraints on it.
StageSchedule & update_schedule(int idx=0)
Get a mutable handle to the stage-specfic schedule for the update stage.
const std::map< std::string, FunctionPtr > & wrappers() const
void add_trace_tag(const std::string &trace_tag)
Expr extern_definition_proxy_expr() const
Get the proxy Expr for the extern stage.
Function(const std::vector< Type > &required_types, int required_dims, const std::string &n)
Construct a new function with the given name, with a requirement that it can only represent Expr(s) o...
A base class for passes over the IR which modify it (e.g.
Definition: IRMutator.h:26
A base class for algorithms that need to recursively walk over the IR.
Definition: IRVisitor.h:19
A reference-counted handle on a reduction domain, which is just a vector of ReductionVariable.
Definition: Reduction.h:33
A schedule for a single stage of a Halide pipeline.
Definition: Schedule.h:698
Create a small array of Exprs for defining and calling functions with multiple outputs.
Definition: Tuple.h:18
std::pair< std::vector< Function >, std::map< std::string, Function > > deep_copy(const std::vector< Function > &outputs, const std::map< std::string, Function > &env)
Deep copy an entire Function DAG.
Expr substitute(const std::string &name, const Expr &replacement, const Expr &expr)
Substitute variables with the given name with the replacement expression within expr.
std::atomic< int > random_variable_counter
This file defines the class FunctionDAG, which is our representation of a Halide pipeline,...
NameMangling
An enum to specify calling convention for extern stages.
Definition: Function.h:26
@ C
No name mangling.
@ CPlusPlus
C++ name mangling.
@ Default
Match whatever is specified in the Target.
DeviceAPI
An enum describing a type of device API.
Definition: DeviceAPI.h:15
A fragment of Halide syntax.
Definition: Expr.h:258
An argument to an extern-defined Func.
A function call.
Definition: IR.h:490
This lets you use a Function as a key in a map of the form map<Function, Foo, Function::Compare>
Definition: Function.h:45
bool operator()(const Function &a, const Function &b) const
Definition: Function.h:46
A possibly-weak pointer to a Halide function.
Definition: FunctionPtr.h:27
bool defined() const
Check if the reference is defined.
Definition: FunctionPtr.h:74
bool same_as(const FunctionPtr &other) const
Check if two FunctionPtrs refer to the same Function.
Definition: FunctionPtr.h:79
A struct representing a target machine and os to generate code for.
Definition: Target.h:19
Types in the halide type system.
Definition: Type.h:283