Re: define-inlinable

[Andreas Rottmann <a.rottmann@gmx.at>]

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ludo@gnu.org (Ludovic Courtès) writes:

> Hello!
>
> Andreas Rottmann <a.rottmann@gmx.at> writes:
>
>> Subject: Move `define-inlinable' into the default namespace
>>
>> +@node Inlinable Procedures
>> +@subsection Inlinable Procedures
>> +
>> +You can define an ``inlinable procedure'' by using
>
> Use @dfn{inlinable procedure} here.
>
Done.

>> +@code{define-inlinable} instead of @code{define}. An inlinable procedure
>
> I prefer two-spaces-after-period, but there’s no consensus.
>
I try to use two spaces in English text as well, but being a German
native speaker (where this is against typographical rules, AFAIK), I
slip sometimes.  Fixed.

>> +behaves the same as a regular procedure, but direct calls will result in
>> +the procedure body being inlined into the caller.
>> +
>> +Making a procedure inlinable eliminates the overhead of the call,
>
> How about:
>
>   Procedures defined with @code{define-inlinable} are @emph{always}
>   inlined, at all call sites.  This eliminates function call overhead at
>   the expense of an increase in code size.
>
Folded in, with the addition of using ".., at _direct_ call sites.".
There's no inlining happening when you use `apply', or rebind the
procedure with `let'.  Should this be made more explicit?

>> but at
>> +the same time means that the caller will not transparently use the new
>> +definition if the inline procedure is redefined.
>
>   ... redefined using @code{set!}.
>
I don't agree with that one: there are multiple ways a procedure can get
"redefined", `set!' being just one of them.  I was actually thinking
more of re-evaluating the procedure definition or something like
`geiser-compile-file', hence I left the text like it was, being more
vague.

>> Inlinable procedures
>> +will also not deal nicely with debugging and tracing.
>
> Instead of “not deal nicely”, what about something like:
>
>   It is not possible to trace an inlined procedures or install a
>   breakpoint in it (@pxref{Traps}).
>
Done.

>> Therefore, you
>> +should not make a procedure inlinable unless it demonstrably improves
>> +performance in a crucial way.
>> +
>> +In general, only small procedures should be considered for inlining, as
>> +making large procedures inlinable will probably result in an increase in
>> +code size.  Additionally, the elimination of the call overhead rarely
>> +matters for for large procedures.
>> +
>> +@deffn {Scheme Syntax} define-inlinable (name parameter ...) . body
>
> I’d write “body ...” instead of “. body”.  Besides being aesthetically
> nicer, the former matches a proper list whereas the latter matches a
> pair.
>
Agreed, and done.

Updated patch attached, is it OK to push this way?


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From: Andreas Rottmann <a.rottmann@gmx.at>
Subject: Move `define-inlinable' into the default namespace

* module/ice-9/boot-9.scm (define-inlineable): Moved here from SRFI-9.
* module/srfi/srfi-9 (define-inlinable): Removed here.

* doc/ref/api-procedures.texi (Inlinable Procedures): Add subsection
  about `define-inlinable'.

---
 doc/ref/api-procedures.texi |   29 ++++++++++++++++++++++++++++-
 module/ice-9/boot-9.scm     |   36 ++++++++++++++++++++++++++++++++++++
 module/srfi/srfi-9.scm      |   32 --------------------------------
 3 files changed, 64 insertions(+), 33 deletions(-)

diff --git a/doc/ref/api-procedures.texi b/doc/ref/api-procedures.texi
index 02889c4..5c6d380 100644
--- a/doc/ref/api-procedures.texi
+++ b/doc/ref/api-procedures.texi
@@ -1,6 +1,6 @@
 @c -*-texinfo-*-
 @c This is part of the GNU Guile Reference Manual.
-@c Copyright (C)  1996, 1997, 2000, 2001, 2002, 2003, 2004, 2009, 2010
+@c Copyright (C)  1996, 1997, 2000, 2001, 2002, 2003, 2004, 2009, 2010, 2011
 @c   Free Software Foundation, Inc.
 @c See the file guile.texi for copying conditions.
 
@@ -16,6 +16,7 @@
 * Higher-Order Functions::      Function that take or return functions.
 * Procedure Properties::        Procedure properties and meta-information.
 * Procedures with Setters::     Procedures with setters.
+* Inlinable Procedures::        Procedures that can be inlined.
 @end menu
 
 
@@ -797,6 +798,32 @@ Return the setter of @var{proc}, which must be either a procedure with
 setter or an operator struct.
 @end deffn
 
+@node Inlinable Procedures
+@subsection Inlinable Procedures
+
+You can define an @dfn{inlinable procedure} by using
+@code{define-inlinable} instead of @code{define}.  An inlinable
+procedure behaves the same as a regular procedure, but direct calls will
+result in the procedure body being inlined into the caller.
+
+Procedures defined with @code{define-inlinable} are @emph{always}
+inlined, at all direct call sites.  This eliminates function call
+overhead at the expense of an increase in code size.  Additionally, the
+caller will not transparently use the new definition if the inline
+procedure is redefined.  It is not possible to trace an inlined
+procedures or install a breakpoint in it (@pxref{Traps}).  For these
+reasons, you should not make a procedure inlinable unless it
+demonstrably improves performance in a crucial way.
+
+In general, only small procedures should be considered for inlining, as
+making large procedures inlinable will probably result in an increase in
+code size.  Additionally, the elimination of the call overhead rarely
+matters for for large procedures.
+
+@deffn {Scheme Syntax} define-inlinable (name parameter ...) body ...
+Define @var{name} as a procedure with parameters @var{parameter}s and
+body @var{body}.
+@end deffn
 
 @c Local Variables:
 @c TeX-master: "guile.texi"
diff --git a/module/ice-9/boot-9.scm b/module/ice-9/boot-9.scm
index 33aa333..327e3fa 100644
--- a/module/ice-9/boot-9.scm
+++ b/module/ice-9/boot-9.scm
@@ -3497,6 +3497,42 @@ module '(ice-9 q) '(make-q q-length))}."
                          x)))))
 
 \f
+;;; Defining transparently inlinable procedures
+;;;
+
+(define-syntax define-inlinable
+  ;; Define a macro and a procedure such that direct calls are inlined, via
+  ;; the macro expansion, whereas references in non-call contexts refer to
+  ;; the procedure.  Inspired by the `define-integrable' macro by Dybvig et al.
+  (lambda (x)
+    ;; Use a space in the prefix to avoid potential -Wunused-toplevel
+    ;; warning
+    (define prefix (string->symbol "% "))
+    (define (make-procedure-name name)
+      (datum->syntax name
+                     (symbol-append prefix (syntax->datum name)
+                                    '-procedure)))
+
+    (syntax-case x ()
+      ((_ (name formals ...) body ...)
+       (identifier? #'name)
+       (with-syntax ((proc-name  (make-procedure-name #'name))
+                     ((args ...) (generate-temporaries #'(formals ...))))
+         #`(begin
+             (define (proc-name formals ...)
+               body ...)
+             (define-syntax name
+               (lambda (x)
+                 (syntax-case x ()
+                   ((_ args ...)
+                    #'((lambda (formals ...)
+                         body ...)
+                       args ...))
+                   (_
+                    (identifier? x)
+                    #'proc-name))))))))))
+
+\f
 
 (define using-readline?
   (let ((using-readline? (make-fluid)))
diff --git a/module/srfi/srfi-9.scm b/module/srfi/srfi-9.scm
index f9449a6..ad9e95d 100644
--- a/module/srfi/srfi-9.scm
+++ b/module/srfi/srfi-9.scm
@@ -64,38 +64,6 @@
 
 (cond-expand-provide (current-module) '(srfi-9))
 
-(define-syntax define-inlinable
-  ;; Define a macro and a procedure such that direct calls are inlined, via
-  ;; the macro expansion, whereas references in non-call contexts refer to
-  ;; the procedure.  Inspired by the `define-integrable' macro by Dybvig et al.
-  (lambda (x)
-    ;; Use a space in the prefix to avoid potential -Wunused-toplevel
-    ;; warning
-    (define prefix (string->symbol "% "))
-    (define (make-procedure-name name)
-      (datum->syntax name
-                     (symbol-append prefix (syntax->datum name)
-                                    '-procedure)))
-
-    (syntax-case x ()
-      ((_ (name formals ...) body ...)
-       (identifier? #'name)
-       (with-syntax ((proc-name  (make-procedure-name #'name))
-                     ((args ...) (generate-temporaries #'(formals ...))))
-         #`(begin
-             (define (proc-name formals ...)
-               body ...)
-             (define-syntax name
-               (lambda (x)
-                 (syntax-case x ()
-                   ((_ args ...)
-                    #'((lambda (formals ...)
-                         body ...)
-                       args ...))
-                   (_
-                    (identifier? x)
-                    #'proc-name))))))))))
-
 (define-syntax define-record-type
   (lambda (x)
     (define (field-identifiers field-specs)
-- 
tg: (ce60660..) t/refactor-define-inlinable (depends on: stable-2.0)

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Thanks for the review, Rotty
-- 
Andreas Rottmann -- <http://rotty.yi.org/>