--- gforth/glocals.fs 1996/05/13 16:36:58 1.22 +++ gforth/glocals.fs 1997/10/04 17:33:53 1.35 @@ -85,7 +85,7 @@ \ Currently locals may only be \ defined at the outer level and TO is not supported. -require search-order.fs +require search.fs require float.fs : compile-@local ( n -- ) \ gforth compile-fetch-local @@ -104,6 +104,21 @@ require float.fs ( otherwise ) dup postpone f@local# , endcase ; +\ locals stuff needed for control structures + +: compile-lp+! ( n -- ) \ gforth compile-l-p-plus-store + dup negate locals-size +! + 0 over = if + else -1 cells over = if postpone lp- + else 1 floats over = if postpone lp+ + else 2 floats over = if postpone lp+2 + else postpone lp+!# dup , + then then then then drop ; + +: adjust-locals-size ( n -- ) \ gforth + \ sets locals-size to n and generates an appropriate lp+! + locals-size @ swap - compile-lp+! ; + \ the locals stack grows downwards (see primitives) \ of the local variables of a group (in braces) the leftmost is on top, \ i.e. by going onto the locals stack the order is reversed. @@ -142,6 +157,55 @@ variable locals-dp \ so here's the speci swap ! postpone >l ; +\ locals list operations + +: common-list ( list1 list2 -- list3 ) \ gforth-internal +\ list1 and list2 are lists, where the heads are at higher addresses than +\ the tail. list3 is the largest sublist of both lists. + begin + 2dup u<> + while + 2dup u> + if + swap + then + @ + repeat + drop ; + +: sub-list? ( list1 list2 -- f ) \ gforth-internal +\ true iff list1 is a sublist of list2 + begin + 2dup u< + while + @ + repeat + = ; + +: list-size ( list -- u ) \ gforth-internal +\ size of the locals frame represented by list + 0 ( list n ) + begin + over 0<> + while + over + ((name>)) >body @ max + swap @ swap ( get next ) + repeat + faligned nip ; + +: set-locals-size-list ( list -- ) + dup locals-list ! + list-size locals-size ! ; + +: check-begin ( list -- ) +\ warn if list is not a sublist of locals-list + locals-list @ sub-list? 0= if + \ !! print current position + ." compiler was overly optimistic about locals at a BEGIN" cr + \ !! print assumption and reality + then ; + : compile-pushlocal-f ( a-addr -- ) ( run-time: f -- ) locals-size @ alignlp-f float+ dup locals-size ! swap ! @@ -255,25 +319,32 @@ previous true abort" this should not happen: new-locals-reveal" ; create new-locals-map ( -- wordlist-map ) -' new-locals-find A, ' new-locals-reveal A, +' new-locals-find A, +' new-locals-reveal A, +' drop A, \ rehash method +' drop A, +slowvoc @ +slowvoc on vocabulary new-locals +slowvoc ! new-locals-map ' new-locals >body cell+ A! \ !! use special access words variable old-dpp \ and now, finally, the user interface words -: { ( -- addr wid 0 ) \ gforth open-brace +: { ( -- lastxt wid 0 ) \ gforth open-brace dp old-dpp ! locals-dp dpp ! + lastxt get-current also new-locals - also get-current locals definitions locals-types + also locals definitions locals-types 0 TO locals-wordlist 0 postpone [ ; immediate locals-types definitions -: } ( addr wid 0 a-addr1 xt1 ... -- ) \ gforth close-brace +: } ( lastxt wid 0 a-addr1 xt1 ... -- ) \ gforth close-brace \ ends locals definitions ] old-dpp @ dpp ! begin @@ -283,8 +354,8 @@ locals-types definitions repeat drop locals-size @ alignlp-f locals-size ! \ the strictest alignment - set-current previous previous + set-current lastcfa ! locals-list TO locals-wordlist ; : -- ( addr wid 0 ... -- ) \ gforth dash-dash @@ -381,20 +452,7 @@ forth definitions \ If this assumption is too optimistic, the compiler will warn the user. -\ Implementation: migrated to kernal.fs - -\ THEN (another control flow from before joins the current one): -\ The new locals-list is the intersection of the current locals-list and -\ the orig-local-list. The new locals-size is the (alignment-adjusted) -\ size of the new locals-list. The following code is generated: -\ lp+!# (current-locals-size - orig-locals-size) -\ : -\ lp+!# (orig-locals-size - new-locals-size) - -\ Of course "lp+!# 0" is not generated. Still this is admittedly a bit -\ inefficient, e.g. if there is a locals declaration between IF and -\ ELSE. However, if ELSE generates an appropriate "lp+!#" before the -\ branch, there will be none after the target . +\ Implementation: \ explicit scoping @@ -428,9 +486,85 @@ forth definitions lastcfa ! last ! DEFERS ;-hook ; +\ THEN (another control flow from before joins the current one): +\ The new locals-list is the intersection of the current locals-list and +\ the orig-local-list. The new locals-size is the (alignment-adjusted) +\ size of the new locals-list. The following code is generated: +\ lp+!# (current-locals-size - orig-locals-size) +\ : +\ lp+!# (orig-locals-size - new-locals-size) + +\ Of course "lp+!# 0" is not generated. Still this is admittedly a bit +\ inefficient, e.g. if there is a locals declaration between IF and +\ ELSE. However, if ELSE generates an appropriate "lp+!#" before the +\ branch, there will be none after the target . + +: (then-like) ( orig -- ) + dead-orig = + if + >resolve drop + else + dead-code @ + if + >resolve set-locals-size-list dead-code off + else \ both live + over list-size adjust-locals-size + >resolve + locals-list @ common-list dup list-size adjust-locals-size + locals-list ! + then + then ; + +: (begin-like) ( -- ) + dead-code @ if + \ set up an assumption of the locals visible here. if the + \ users want something to be visible, they have to declare + \ that using ASSUME-LIVE + backedge-locals @ set-locals-size-list + then + dead-code off ; + +\ AGAIN (the current control flow joins another, earlier one): +\ If the dest-locals-list is not a subset of the current locals-list, +\ issue a warning (see below). The following code is generated: +\ lp+!# (current-local-size - dest-locals-size) +\ branch + +: (again-like) ( dest -- addr ) + over list-size adjust-locals-size + swap check-begin POSTPONE unreachable ; + +\ UNTIL (the current control flow may join an earlier one or continue): +\ Similar to AGAIN. The new locals-list and locals-size are the current +\ ones. The following code is generated: +\ ?branch-lp+!# (current-local-size - dest-locals-size) + +: (until-like) ( list addr xt1 xt2 -- ) + \ list and addr are a fragment of a cs-item + \ xt1 is the conditional branch without lp adjustment, xt2 is with + >r >r + locals-size @ 2 pick list-size - dup if ( list dest-addr adjustment ) + r> drop r> compile, + swap compile, drop + then ( list ) + check-begin ; + +: (exit-like) ( -- ) + 0 adjust-locals-size ; + ' locals-:-hook IS :-hook ' locals-;-hook IS ;-hook +' (then-like) IS then-like +' (begin-like) IS begin-like +' (again-like) IS again-like +' (until-like) IS until-like +' (exit-like) IS exit-like + \ The words in the locals dictionary space are not deleted until the end \ of the current word. This is a bit too conservative, but very simple. @@ -441,10 +575,6 @@ forth definitions \ things above are not control flow joins. Everything should be taken \ over from the live flow. No lp+!# is generated. -\ !! The lp gymnastics for UNTIL are also a real problem: locals cannot be -\ used in signal handlers (or anything else that may be called while -\ locals live beyond the lp) without changing the locals stack. - \ About warning against uses of dead locals. There are several options: \ 1) Do not complain (After all, this is Forth;-) @@ -489,10 +619,9 @@ forth definitions \ this gives a unique identifier for the way the xt was defined \ words defined with different does>-codes have different definers \ the definer can be used for comparison and in definer! - dup >code-address [ ' spaces >code-address ] Literal = - \ !! this definition will not work on some implementations for `bits' - if \ if >code-address delivers the same value for all does>-def'd words - >does-code 1 or \ bit 0 marks special treatment for does codes + dup >does-code + ?dup-if + nip 1 or else >code-address then ; @@ -505,29 +634,33 @@ forth definitions code-address! then ; -: TO ( c|w|d|r "name" -- ) \ core-ext,local +:noname + ' dup >definer [ ' locals-wordlist ] literal >definer = + if + >body ! + else + -&32 throw + endif ; +:noname 0 0 0. 0.0e0 { c: clocal w: wlocal d: dlocal f: flocal } - ' dup >definer + comp' drop dup >definer case - [ ' locals-wordlist >definer ] literal \ value + [ ' locals-wordlist ] literal >definer \ value OF >body POSTPONE Aliteral POSTPONE ! ENDOF - [ ' clocal >definer ] literal + \ !! dependent on c: etc. being does>-defining words + \ this works, because >definer uses >does-code in this case, + \ which produces a relocatable address + [ comp' clocal drop >definer ] literal OF POSTPONE laddr# >body @ lp-offset, POSTPONE c! ENDOF - [ ' wlocal >definer ] literal + [ comp' wlocal drop >definer ] literal OF POSTPONE laddr# >body @ lp-offset, POSTPONE ! ENDOF - [ ' dlocal >definer ] literal + [ comp' dlocal drop >definer ] literal OF POSTPONE laddr# >body @ lp-offset, POSTPONE 2! ENDOF - [ ' flocal >definer ] literal + [ comp' flocal drop >definer ] literal OF POSTPONE laddr# >body @ lp-offset, POSTPONE f! ENDOF -&32 throw - endcase ; immediate -interpretation: - ' dup >definer [ ' locals-wordlist >definer ] literal = - if - >body ! - else - -&32 throw - endif ; + endcase ; +interpret/compile: TO ( c|w|d|r "name" -- ) \ core-ext,local : locals| \ don't use 'locals|'! use '{'! A portable and free '{'