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This is the constantfold Reference Manual, version 0.1, generated automatically by Declt version 3.0 "Montgomery Scott" on Wed Mar 25 17:53:42 2020 GMT+0.
| • Introduction | What constantfold is all about | |
| • Systems | The systems documentation | |
| • Files | The files documentation | |
| • Packages | The packages documentation | |
| • Definitions | The symbols documentation | |
| • Indexes | Concepts, functions, variables and data types |
* Constantfold - User-defined constant folding facility
This is a supporting library for NUMCL.
It provides a single macro, =(constantfold name &key commutative associative copier)=.
=constantfold= registers the function =NAME= as an additional form that is
considered as a candidate for a constant. For example,
#+begin_src lisp
(defstruct point2d
(x 0 :type 'real)
(y 0 :type 'real))
(defun point2d-add/2 (p1 p2)
(ematch* (p1 p2)
(((point2d :x x1 :y y1)
(point2d :x x2 :y y2))
(make-point2d :x (+ x1 x2) :y (+ y1 y2)))))
(defun point2d-add (&rest args)
(reduce #'point2d-add/2 args))
(constantfold make-point2d :copier copy-point2d)
(constantfold point2d-add :copier copy-point2d :commutative t :associative t)
#+end_src
This allows the compiler to constant fold
#+begin_src lisp
(defun fn1 () (point2d-add (make-point2d :x 1 :y 2) (make-point2d :x 3 :y 4)))
#+end_src
and
#+begin_src lisp
(defun fn1 () (point2d-add #S(point2d :x 1 :y 2) #S(point2d :x 3 :y 4)))
#+end_src
into
#+begin_src lisp
(defun fn1 () (copy-point2d #S(point2d :x 4 :y 6))).
#+end_src
When =:associative= and/or =:commutative= is true, it performs the corresponding
code morphing and tries to fold constants as much as possible. For example,
#+begin_src lisp
(defun fn2 (p1 p2 x y)
(point2d-add (make-point2d :x 1 :y 2)
p1
(make-point2d :x 3 :y 4)
p2
(make-point2d :x x :y y)))
#+end_src
gets compiled into
#+begin_src lisp
(defun fn2 (p1 p2 x y)
(point2d-add (copy-point2d #S(point2d :x 4 :y 6))
p1
p2
(make-point2d :x x :y y)))
#+end_src
due to commutativity.
This library preserves the original semantics of the code. For example,
#+begin_src lisp
(defun fn3 ()
(make-point2d :x 1 :y 2))
#+end_src
originally always instantiates a new object. This is compiled into
#+begin_src lisp
(defun fn3 ()
(copy-point2d #S(point2d :x 1 :y 2)))
#+end_src
which also instantiates a new object.
The reason why =fn1/fn2= are allowed to remove some instance creations while
=fn3= does not perform the pruning is that the result of =make-point2d= in =fn1/fn2=
are so-called *rvalues* which are not visible to the user
while the result of =(make-point2d :x 1 :y 2)= is going to be returned to the user
and is thus an *lvalue*.
It might then be confusing why =fn2= does not completely remove the instantiation.
This is because =point2d-add= may perform a destructive operation on the argument,
and thus the value (e.g. slots) of the constant could be modified.
=copy-point2d= is called in order to avoid the effect of this destructive operation.
COPIER could be ommited when the object is known to be immutable
and there is no need for copying the object.
In this case the compilation result always returns the same object under =EQ=.
Note that if the result of the constant folding is an object of class
=CL:STANDARD-OBJECT= / =CL:STRUCTURE-OBJECT= / =CL:CONDITION= / =CL:CLASS=, the
corresponding =CL:MAKE-LOAD-FORM= method should be defined.
** Dependencies
This library is at least tested on implementation listed below:
+ SBCL 1.4.12 on X86-64 Linux 4.4.0-141-generic (author's environment)
+ SBCL 1.5.1 on X86-64 Linux 4.4.0-141-generic (author's environment)
Also, it depends on the following libraries:
+ trivia by *Masataro Asai* :
NON-optimized pattern matcher compatible with OPTIMA, with extensible optimizer interface and clean codebase
+ alexandria by *Nikodemus Siivola , and others.* :
Alexandria is a collection of portable public domain utilities.
+ iterate by ** :
Jonathan Amsterdam's iterator/gatherer/accumulator facility
+ lisp-namespace by *Masataro Asai* :
Provides LISP-N --- extensible namespaces in Common Lisp.
[[./constantfold.png]]
** Author, License, Copyright
Masataro Asai (guicho2.71828@gmail.com)
Licensed under LGPL v3.
Copyright (c) 2019 IBM Corporation
Next: Files, Previous: Introduction, Up: Top [Contents][Index]
The main system appears first, followed by any subsystem dependency.
| • The constantfold system |
Masataro Asai
LGPL
User-defined constant folding facility
0.1
constantfold.asd (file)
package.lisp (file)
Files are sorted by type and then listed depth-first from the systems components trees.
| • Lisp files |
| • The constantfold.asd file | ||
| • The constantfold/package.lisp file |
Next: The constantfold/package․lisp file, Previous: Lisp files, Up: Lisp files [Contents][Index]
/home/quickref/quicklisp/dists/quicklisp/software/constantfold-20191227-git/constantfold.asd
constantfold (system)
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constantfold (system)
package.lisp
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Packages are listed by definition order.
| • The constantfold package |
package.lisp (file)
Definitions are sorted by export status, category, package, and then by lexicographic order.
| • Exported definitions | ||
| • Internal definitions |
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| • Exported macros | ||
| • Exported functions |
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Registers a constant folding compiler macros to the function NAME.
package.lisp (file)
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Unregister the compiler macro
package.lisp (file)
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| • Internal special variables | ||
| • Internal compiler macros | ||
| • Internal functions | ||
| • Internal conditions | ||
| • Internal types |
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package.lisp (file)
package.lisp (file)
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Performs constant-folding for associative functions.
Following optimization is performed:
(+ a 2 3 b) –> (+ a (+ 2 3) b) –> (+ a 5 b)
package.lisp (file)
Performs constant-folding for commutative and associative functions.
Following optimization is performed:
(+ a 2 3 b 1) –> (+ (+ 2 3 1) a b) –> (+ 6 a b)
package.lisp (file)
Performs a simple constant-folding. Constantfold when all arguments are constants.
package.lisp (file)
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package.lisp (file)
package.lisp (file)
package.lisp (file)
Extracts the name of the function from the &whole argument of a compiler macro.
package.lisp (file)
Automatically defined boolean function.
package.lisp (file)
package.lisp (file)
Recursively checks if the form is a constant form.
Returns a boolean. When FORM is a standard constant form reconized by
constantp, it also returns T as the secondary value.
package.lisp (file)
package.lisp (file)
Flattens a tree of forms of the same functions. For example, (+ (+ 2 3) (+ 5 6)) into (+ 2 3 5 6).
package.lisp (file)
package.lisp (file)
Automatically defined getter function. When DEFAULT is supplied, the value is set automatically.
package.lisp (file)
(setf symbol-constant-form) (function)
Automatically defined setter function.
package.lisp (file)
symbol-constant-form (function)
Allows further calls to the compiler macro.
package.lisp (file)
Suppresses further calls to the compiler macro which otherwise causes an infinite loop.
package.lisp (file)
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package.lisp (file)
unbound-variable (condition)
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package.lisp (file)
Previous: Definitions, Up: Top [Contents][Index]
| • Concept index | ||
| • Function index | ||
| • Variable index | ||
| • Data type index |
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