File:  [gforth] / gforth / profile.fs
Revision 1.5: download - view: text, annotated - select for diffs
Mon Dec 31 19:02:24 2007 UTC (9 years, 9 months ago) by anton
Branches: MAIN
CVS tags: v0-7-0, HEAD
updated copyright year after changing license notice

\ count execution of control-flow edges

\ Copyright (C) 2004,2007 Free Software Foundation, Inc.

\ This file is part of Gforth.

\ Gforth is free software; you can redistribute it and/or
\ modify it under the terms of the GNU General Public License
\ as published by the Free Software Foundation, either version 3
\ of the License, or (at your option) any later version.

\ This program is distributed in the hope that it will be useful,
\ but WITHOUT ANY WARRANTY; without even the implied warranty of
\ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
\ GNU General Public License for more details.

\ You should have received a copy of the GNU General Public License
\ along with this program. If not, see http://www.gnu.org/licenses/.


\ relies on some Gforth internals

\ !! assumption: each file is included only once; otherwise you get
\ the counts for just one of the instances of the file.  This can be
\ fixed by making sure that every source position occurs only once as
\ a profile point.

true constant count-calls? \ do some profiling of colon definitions etc.

\ for true COUNT-CALLS?:

\ What data do I need for evaluating the effectiveness of (partial) inlining?

\ static and dynamic counts of everything:

\ original BB length (histogram and average)
\ BB length with partial inlining (histogram and average)
\   since we cannot partially inline library calls, we use a parameter
\   that represents the amount of partial inlining we can expect there.
\ number of tail calls (original and after partial inlining)
\ number of calls (original and after partial inlining)
\ reason for BB end: call, return, execute, branch

\ how many static calls are there to a word?  How many of the dynamic
\ calls call just a single word?

struct
    cell%    field profile-next
    cell% 2* field profile-count
    cell% 2* field profile-sourcepos
    cell%    field profile-char \ character position in line
    count-calls? [if]
	cell% field profile-colondef? \ is this a colon definition start
	cell% field profile-calls \ static calls to the colon def
	cell% field profile-straight-line \ may contain calls, but no other CF
	cell% field profile-calls-from \ static calls in the colon def
    [endif]
end-struct profile% \ profile point

variable profile-points \ linked list of profile%
0 profile-points !
variable next-profile-point-p \ the address where the next pp will be stored
profile-points next-profile-point-p !
count-calls? [if]
    variable last-colondef-profile \ pointer to the pp of last colon definition
[endif]
    
: new-profile-point ( -- addr )
    profile% %alloc >r
    0. r@ profile-count 2!
    current-sourcepos r@ profile-sourcepos 2!
    >in @ r@ profile-char !
    [ count-calls? ] [if]
	r@ profile-colondef? off
	0 r@ profile-calls !
	r@ profile-straight-line on
	0 r@ profile-calls-from !
    [endif]
    0 r@ profile-next !
    r@ next-profile-point-p @ !
    r@ profile-next next-profile-point-p !
    r> ;

: print-profile ( -- )
    profile-points @ begin
	dup while
	    dup >r
	    r@ profile-sourcepos 2@ .sourcepos ." :"
	    r@ profile-char @ 0 .r ." : "
	    r@ profile-count 2@ 0 d.r cr
	    r> profile-next @
    repeat
    drop ;

: print-profile-coldef ( -- )
    profile-points @ begin
	dup while
	    dup >r
	    r@ profile-colondef? @ if
		r@ profile-sourcepos 2@ .sourcepos ." :"
		r@ profile-char @ 0 .r ." : "
		r@ profile-count 2@ 0 d.r
		r@ profile-straight-line @ space .
		cr
	    endif
	    r> profile-next @
    repeat
    drop ;


: dinc ( d-addr -- )
    \ increment double pointed to by d-addr
    dup 2@ 1. d+ rot 2! ;

: profile-this ( -- )
    new-profile-point profile-count POSTPONE literal POSTPONE dinc ;

\ Various words trigger PROFILE-THIS.  In order to avoid getting
\ several calls to PROFILE-THIS from a compiling word (like ?EXIT), we
\ just wait until the next word is parsed by the text interpreter (in
\ compile state) and call PROFILE-THIS only once then.  The whole
\ BEFORE-WORD hooking etc. is there for this.

\ The reason that we do this is because we use the source position for
\ the profiling information, and there's only one source position for
\ ?EXIT.  If we used the threaded code position instead, we would see
\ that ?EXIT compiles to several threaded-code words, and could use
\ different profile points for them.  However, usually dealing with
\ the source is more practical.

\ Another benefit is that we can ask for profiling anywhere in a
\ control-flow word (even before it compiles its own stuff).

\ Potential problem: Consider "COMPILING ] [" where COMPILING compiles
\ a whole colon definition (and triggers our profiler), but during the
\ compilation of the colon definition there is no parsing.  Afterwards
\ you get interpret state at first (no profiling, either), but after
\ the "]" you get parsing in compile state, and PROFILE-THIS gets
\ called (and compiles code that is never executed).  It would be
\ better if we had a way of knowing whether we are in a colon def or
\ not (and used that knowledge instead of STATE).

Defer before-word-profile ( -- )
' noop IS before-word-profile

: before-word1 ( -- )
    before-word-profile defers before-word ;

' before-word1 IS before-word

: profile-this-compiling ( -- )
    state @ if
	profile-this
	['] noop IS before-word-profile
    endif ;

: cock-profiler ( -- )
    \ as in cock the gun - pull the trigger
    ['] profile-this-compiling IS before-word-profile
    [ count-calls? ] [if] \ we are at a non-colondef profile point
	last-colondef-profile @ profile-straight-line off
    [endif]
;

: hook-profiling-into ( "name" -- )
    \ make (deferred word) "name" call cock-profiler, too
    ' >body >r :noname
    POSTPONE cock-profiler
    r@ @ compile, \ old hook behaviour
    POSTPONE ;
    r> ! ; \ change hook behaviour

hook-profiling-into then-like
\ hook-profiling-into if-like    \ subsumed by other-control-flow
\ hook-profiling-into ahead-like \ subsumed by other-control-flow
hook-profiling-into other-control-flow
hook-profiling-into begin-like
hook-profiling-into again-like
hook-profiling-into until-like

count-calls? [if]
    : :-hook-profile ( -- )
	defers :-hook
	next-profile-point-p @
	profile-this
	@ dup last-colondef-profile !
	profile-colondef? on ;

    ' :-hook-profile IS :-hook
[else]
    hook-profiling-into exit-like
    hook-profiling-into :-hook
[endif]

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