Halide
CSE.h
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1 #ifndef HALIDE_INTERNAL_CSE_H
2 #define HALIDE_INTERNAL_CSE_H
3 
4 /** \file
5  * Defines a pass for introducing let expressions to wrap common sub-expressions. */
6 
7 #include "Expr.h"
8 
9 namespace Halide {
10 namespace Internal {
11 
12 /** Replace each common sub-expression in the argument with a
13  * variable, and wrap the resulting expr in a let statement giving a
14  * value to that variable.
15  *
16  * This is important to do within Halide (instead of punting to llvm),
17  * because exprs that come in from the front-end are small when
18  * considered as a graph, but combinatorially large when considered as
19  * a tree. For an example of a such a case, see
20  * test/code_explosion.cpp
21  *
22  * The last parameter determines whether all common subexpressions are
23  * lifted, or only those that the simplifier would not subsitute back
24  * in (e.g. addition of a constant).
25  */
26 Expr common_subexpression_elimination(const Expr &, bool lift_all = false);
27 
28 /** Do common-subexpression-elimination on each expression in a
29  * statement. Does not introduce let statements. */
30 Stmt common_subexpression_elimination(const Stmt &, bool lift_all = false);
31 
32 void cse_test();
33 
34 } // namespace Internal
35 } // namespace Halide
36 
37 #endif
Halide::Internal::cse_test
void cse_test()
Halide::Internal::common_subexpression_elimination
Expr common_subexpression_elimination(const Expr &, bool lift_all=false)
Replace each common sub-expression in the argument with a variable, and wrap the resulting expr in a ...
Halide
This file defines the class FunctionDAG, which is our representation of a Halide pipeline,...
Definition: AddAtomicMutex.h:21
Halide::LinkageType::Internal
@ Internal
Not visible externally, similar to 'static' linkage in C.
Expr.h