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revision 660, Thu Jun 15 04:40:56 2000 UTC revision 715, Thu Nov 2 07:51:04 2000 UTC
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11  Date:  Date:
12  Tag: <post-commit CVS tag>  Tag: <post-commit CVS tag>
13  Description:  Description:
14    
15    ----------------------------------------------------------------------
16    Name: Matthias Blume
17    Date: 2000/11/02 17:00:00 JST
18    Tag: blume-20001102-condcomp
19    Description:
20    
21    - Small tweaks to pickler -- new BOOTFILES!
22    - Version bumped to 110.29.2.
23    - Added conditional compilation facility to init.cmi (see comment there).
24    ----------------------------------------------------------------------
25    Name: Allen Leung
26    Date: 2000/10/23 19:31:00
27    Tag: leunga-20001023-demo-ra
28    
29    1. Minor RA changes that improves spilling on x86 (affects Moby and C-- only)
30    2. Test programs for the graph library updated
31    3. Some new MLRISC demo programs added
32    
33    ----------------------------------------------------------------------
34    Name: Matthias Blume
35    Date: 2000/08/31 22:15:00 JST
36    Tag: blume-20001017-errmsg
37    Description:
38    
39    More error message grief: Where there used to be no messages, there
40    now were some that had bogus error regions.  Fixed.
41    
42    ----------------------------------------------------------------------
43    Name: Matthias Blume
44    Date: 2000/08/31 17:30:00 JST
45    Tag: blume-20001017-v110p29p1
46    Description:
47    
48    I made a version 110.29.1 with new bootfiles.
49    
50    Changes:  Modified pickler/unpickler for faster and leaner unpickling.
51              CM documentation changes and a small bugfix in CM's error reporting.
52    
53    ----------------------------------------------------------------------
54    Name: Lal George
55    Date: 2000/09/27 14:42:35 EDT
56    Tag: george-20000927-nodestatus
57    Description:
58    
59    Changed the type of the nodestatus, so that:
60    
61            SPILLED(~1)             is now SPILLED
62            SPILLED(m) where m>=0   is now MEMREG(m)
63            SPILLED(s) where s<~1   is now SPILL_LOC(~s)
64    
65    ----------------------------------------------------------------------
66    Name: Matthias Blume
67    Date: 2000/09/07 14:45:00 JST
68    Tag: blume-20000907-cmerrmsg
69    Description:
70    
71    Small tweak to CM to avoid getting ML syntax error messages twice.
72    
73    ----------------------------------------------------------------------
74    Name: Matthias Blume
75    Date: 2000/08/31 18:00:00 JST
76    Tag: blume-20000831-cvsbootfiles
77    Description:
78    
79    New URL for boot files (because the 110.29 files on the BL server do
80    now work correctly with my updated install scripts for yacc and lex).
81    
82    ----------------------------------------------------------------------
83    Name: Matthias Blume
84    Date: 2000/08/08 12:33:00 JST
85    Tag: blume-20000808-manual
86    Description:
87    
88    Tiny update to CM manual.
89    
90    ----------------------------------------------------------------------
91    Name: Allen Leung
92    Date: 2000/08/7 19:31:00
93    Tag: leunga-20000807-a-whole-bunch-of-stuff
94    
95      Moby, C--, SSA, x86, machine descriptions etc.  Should only affect C--
96    and Mobdy.
97    
98    1.  x86
99    
100       a.  Fixes to peephole module by John and Dan.
101       b.  Assembly fix to SETcc by Allen.
102       c.  Fix to c-call by John.
103       d.  Fix to spilling by John.  (This one deals with the missing FSTPT case)
104       e.  Instruction selection optimization to SETcc as suggested by John.
105    
106           For example,
107    
108            MV(32, x, COND(32, CMP(32, LT, a, b), LI 1, LI 0))
109    
110           should generate:
111    
112            MOVL a, x
113            SUBL b, x
114            SHRL 31, x
115    
116    2.  IR stuff
117    
118         A bunch of new DJ-graph related algorithms added.  These
119         speed up SSA construction.
120    
121    3.  SSA + Scheduling
122    
123         Added code for SSA and scheduling to the repository
124    
125    ----------------------------------------------------------------------
126    Name: Lal George
127    Date: 2000/07/27 11:53:14 EDT
128    
129    Tag: lal-20000727-linux-ppc
130    Description:
131    
132     Made changes to support Linux PPC.
133     p.s. I have confirmation that the 110.29 boot files work fine.
134    
135    ----------------------------------------------------------------------
136    Name: Matthias Blume
137    Date: 2000/07/27 17:40:00 JST
138    Tag: blume-20000727-scripts
139    Description:
140    
141    !!!! WARNING !!!!
142    You must recompile the runtime system!
143    !!!! WARNING !!!!
144    
145    This is basically another round of script-enhancements:
146    
147    1. sml, ml-build, and ml-makedepend accept options -D and -U to define
148       and undefine CM preprocessor symbols.
149    
150    2. ml-build avoids generating a new heap image if it finds that the
151       existing one is still ok.  (The condition is that no ML file had to
152       be recompiled and all ML files are found to be older that the heap
153       file.)
154    
155       To make this work smoothly, I also hacked the runtime system as
156       well as SMLofNJ.SysInfo to get access to the heap image suffix
157       (.sparc-solaris, ...) that is currently being used.
158    
159       Moreover, the signature of CM.mk_standalone has changed.  See the
160       CM manual.
161    
162    3. ml-makedepend accepts additional options -n, -a, and -o.  (See the
163       CM manual for details.)
164    
165    4. More CM manual updates:
166        - all of the above has been documented.
167        - there is now a section describing the (CM-related) command line
168          arguments that are accepted by the "sml" command
169    
170    ----------------------------------------------------------------------
171    Name: Matthias Blume
172    Date: 2000/07/25 16:20:00 JST
173    Tag: blume-20000725-makedepend
174    Description:
175    
176    Added a script called ml-makedepend.  This can be used in makefiles
177    for Unix' make in a way very similar to the "makedepend" command for
178    C.
179    
180    The script internally uses function CM.sources.
181    
182    Synopsis:
183    
184        ml-makedepend [-f makefile] cmfile targetname
185    
186    The default for the makefile is "makefile" (or "Makefile" should
187    "makefile" not exist).
188    
189    ml-makedepend adds a cmfile/targetname-specific section to this
190    makefile (after removing the previous version of this section).  The
191    section contains a single dependency specification with targetname on
192    the LHS (targetname is an arbitrary name), and a list of files derived
193    from the cmfile on the RHS.  Some of the files on the RHS are
194    ARCH/OPSYS-specific.  Therefore, ml-makedepend inserts references to
195    "make" variables $(ARCH) and $(OPSYS) in place of the corresponding
196    path names.  The makefile writer is responsible for making sure that
197    these variables have correct at the time "make" is invoked.
198    
199    ----------------------------------------------------------------------
200    Name: Matthias Blume
201    Date: 2000/07/22 23:30:00 JST
202    Tag: blume-20000722-urlupdate
203    Description:
204    
205    Changed BOOT and config/srcarchiveurl to point to BL server:
206    
207        ftp://ftp.research.bell-labs.com/dist/smlnj/working/110.29/
208    
209    ----------------------------------------------------------------------
210    Name: Matthias Blume
211    Date: 2000/07/18 18:00:00 JST
212    Tag: blume-20000718-Version_110_29
213    Description:
214    
215    1. Updated src/compiler/TopLevel/main/version.sml to version 110.29
216    
217    2. Updated config/version to 110.29
218    
219    3. Updated config/srcarchiveurl
220    
221    3. New boot files!
222       ftp://ftp.cs.princeton.edu/pub/people/blume/sml/110.29-autofetch
223    
224    ----------------------------------------------------------------------
225    Name: Matthias Blume
226    Date: 2000/07/11 13:58:00 JST
227    Tag: blume-20000711-doctypo
228    Description:
229    
230    Fixed a few typos in CM manual.
231    
232    ----------------------------------------------------------------------
233    Name: Allen Leung
234    Date: 2000/06/15 00:38:00
235    Tag: leunga-20000704-sparc-x86
236    
237    1. x86 peephole improvement sp += k; sp -= k => nop  [from John]
238    2. fix to x86 RET bug [found by Dan Grossman]
239    3. sparc assembly bug fix for ticc instructions [found by Fermin]
240    
241       Affects c-- and moby only
242    
243    ----------------------------------------------------------------------
244    Name: Matthias Blume
245    Date: 2000/07/04 15:26:00
246    Tag: blume-20000704-trigger
247    Description:
248    
249    1. Improvements to CM manual.
250    2. SMLofNJ.Internals.BTrace.trigger reinstated as an alternative way
251       of getting a back-trace.  The function, when called, raises an
252       internal exception which explicitly carries the full back-trace history,
253       so it is unaffected by any intervening handle-raise pairs ("trivial"
254       or not).  The interactive loop will print that history once it arrives
255       at top level.
256       Short of having all exceptions implicitly carry the full history, the
257       recommended way of using this facility is:
258         - compile your program with instrumentation "on"
259         - run it, when it raises an exception, look at the history
260         - if the history is "cut off" because of some handler, go and modify
261           your program so that it explicitly calls BTrace.trigger
262         - recompile (still instrumented), and rerun; look at the full history
263    
264    ----------------------------------------------------------------------
265    Name: Matthias Blume
266    Date: 2000/07/03 15:36:00 JST
267    Tag: blume-20000702-manual
268    Description:
269    
270    Small corrections and updates to CM manual.
271    
272    ----------------------------------------------------------------------
273    Name: Matthias Blume
274    Date: 2000/06/29 16:04:00 JST
275    Tag: blume-20000629-yacctool
276    Description:
277    
278    Changes:
279    
280    1. Class "mlyacc" now takes separate arguments to pass options to
281       generated .sml- and .sig-files independently.
282    2. Corresponding CM manual updates.
283    3. BTrace module now also reports call sites.  (However, for loop clusters
284       it only shows from where the cluster was entered.)  There are associated
285       modifications to core.sml, internals.{sig,sml}, btrace.sml, and btimp.sml.
286    
287    ----------------------------------------------------------------------
288    Name: Matthias Blume
289    Date: 2000/06/27 16:51:00 JST
290    Tag: blume-20000627-noweb
291    Description:
292    
293    Changes:
294    
295     1. Implemented "subdir" and "witness" options for noweb tool.
296        This caused some slight internal changes in CM's tool implementation.
297     2. Fixed bug in "tool plugin" mechanism.  This is essentially cleaning
298        some remaining issues from earlier path anchor changes.
299     3. Updated CM manual accordingly.
300    
301     4. Changed implementation of back-tracing so that I now consider it
302        ready for prime-time.
303    
304        In particular, you don't have to explicitly trigger the back-trace
305        anymore.  Instead, if you are running BTrace-instrumented code and
306        there is an uncaught exception (regardless of whether or not it was
307        raised in instrumented code), the top-level evalloop will print
308        the back-trace.
309    
310        Features:
311    
312          - Instrumented and uninstrumented code work together seemlessly.
313            (Of course, uninstrumented code is never mentioned in actual
314             back-traces.)
315    
316          - Asymptotic time- and space-complexity of instrumented code is
317            equal to that of uninstrumented code.  (This means that
318            tail-recursion is preserved by the instrumentation phase.)
319    
320          - Modules whose code has been instrumented in different sessions
321            work together without problem.
322    
323          - There is no penalty whatsoever on uninstrumented code.
324    
325          - There is no penalty on "raise" expressions, even in
326            instrumented code.
327    
328        A potential bug (or perhaps it is a feature, too):
329    
330          A back-trace reaches no further than the outermost instrumented
331          non-trivial "raise".  Here, a "trivial" raise is one that is the
332          sole RHS of a "handle" rule.  Thus, back-traces reach trough
333    
334               <exp> handle e => raise e
335    
336          and even
337    
338               <exp> handle Foo => raise Bar
339    
340          and, of course, through
341    
342               <exp> handle Foo => ...
343    
344         if the exception was not Foo.
345    
346         Back-traces always reach right through any un-instrumented code
347         including any of its "handle" expressions, trivial or not.
348    
349       To try this out, do the following:
350    
351         - Erase all existing binfiles for your program.
352           (You may keep binfiles for those modules where you think you
353            definitely don't need back-tracing.)
354         - Turn on back-trace instrumentation:
355              SMLofNJ.Internals.BTrace.mode (SOME true);
356         - Recompile your program.  (I.e., run "CM.make" or "use".)
357         - You may now turn instrumentation off again (if you want):
358              SMLofNJ.Internals.BTrace.mode (SOME false);
359         - Run your program as usual.  If it raises an exception that
360           reaches the interactive toplevel, then a back-trace will
361           automatically be printed.  After that, the toplevel loop
362           will print the exception history as usual.
363    
364    ----------------------------------------------------------------------
365    Name: Matthias Blume
366    Date: 2000/06/26 09:56:46 JST
367    Tag: blume-20000626-setup
368    Description:
369    
370    CM: - setup-parameter to "sml" added; this can be used to run arbitrary
371          ML code before and after compiling a file (e.g., to set compiler
372          flags)
373    
374    Compiler: - improved btrace API (in core.sml, internals.{sig,sml})
375              - associated changes to btrace.sml (BTrace instrumentation pass)
376              - cleaner implementation of btimp.sml (BTrace tracing and report
377                module)
378    
379    CM manual: * new path encoding documented
380               * description of setup-parameter to "sml" added
381    
382    The biggest user-visible change to back-tracing is that it is no
383    longer necessary to compile all traced modules within the same
384    session.  (This was a real limitation.)
385    
386    ----------------------------------------------------------------------
387    Name: Matthias Blume
388    Date: 2000/06/24 12:40:00 JST
389    Tag: blume-20000624-startup
390    Description:
391    
392    Fixes startup slowdown problem.  (I was calling SrcPath.sync a _tad_
393    bit too often -- to put it mildly. :)
394    
395    ----------------------------------------------------------------------
396    Name: Matthias Blume
397    Date: 2000/06/23 18:20:00 JST
398    Tag: blume-20000623-btrace
399    Description:
400    
401    This updates adds a backtrace facility to aid programmers in debugging
402    their programs.  This involves the following changes:
403    
404    1. Module system/smlnj/init/core.sml (structure _Core) now has hooks for
405       keeping track of the current call stack.  When programs are compiled
406       in a special mode, the compiler will insert calls to these hooks
407       into the user program.
408       "Hook" means that it is possible for different implementations of
409       back-tracing to register themselves (at different times).
410    
411    2. compiler/MiscUtil/profile/btrace.sml implements the annotation phase
412       as an Absyn.dec->Absyn.dec rewrite.  Normally this phase is turned off.
413       It can be turned on using this call:
414         SMLofNJ.Internals.BTrace.mode (SOME true);
415       Turning it off again:
416         SMLofNJ.Internals.BTrace.mode (SOME false);
417       Querying the current status:
418         SMLofNJ.Internals.BTrace.mode NONE;
419       Annotated programs are about twice as big as normal ones, and they
420       run a factor of 2 to 4 slower with a dummy back-trace plugin (one
421       where all hooks do nothing).  The slowdown with a plugin that is
422       actually useful (such as the one supplied by default) is even greater,
423       but in the case of the default plugin it is still only an constant
424       factor (amortized).
425    
426    3. system/Basis/Implementation/NJ/internals.{sig,sml} have been augmented
427       with a sub-structure BTrace for controlling back-tracing.  In particular,
428       the above-mentioned function "mode" controls whether the annotation
429       phase is invoked by the compiler.  Another important function is
430       "trigger": when called it aborts the current execution and causes
431       the top-level loop to print a full back-trace.
432    
433    4. compiler/MiscUtil/profile/btimp.sml is the current default plugin
434       for back-tracing.  It keeps track of the dynamic call stack and in
435       addition to that it keeps a partial history at each "level" of that
436       stack.  For example, if a tail-calls b, b tail-calls c, and c tail-calls
437       d and b (at separate times, dynamically), then the report will show:
438    
439       GOTO   d
440             /c
441       GOTO  \b
442       CALL   a
443    
444       This shows that there was an initial non-tail call of a, then a
445       tail-call to b or c, looping behavior in a cluster of functions that
446       consist of b and c, and then a goto from that cluster (i.e., either from
447       b or from c) to d.
448    
449       Note that (depending on the user program) the amount of information
450       that the back-trace module has to keep track of at each level is bounded
451       by a constant.  Thus, the whole implementation has the same asymptotical
452       complexity as the original program (both in space and in time).
453    
454    5. compiler/TopLevel/interact/evalloop.sml has been modified to
455       handle the special exception SMLofNJ.Internals.BTrace.BTrace
456       which is raised by the "trigger" function mentioned above.
457    
458    Notes on usage:
459    
460    - Annotated code works well together with unannotated code:
461    Unannotated calls simply do not show up at all in the backtrace.
462    
463    - It is not a good idea to let modules that were annotated during
464    different sessions run at the same time.  This is because the compiler
465    chooses small integers to identify individual functions, and there
466    will be clashes if different modules were compiled in separate sessions.
467    (Nothing will crash, and you will even be told about the clashes, but
468    back-trace information will in general not be useful.)
469    
470    - Back-tracing can be confused by callcc and capture.
471    
472    - The only way of getting a back-trace right now is to explicitly
473    invoke the "trigger" function from your user program.  Eventually, we
474    should make every exception carry back-trace information (if
475    available).  But since this creates more overhead at "raise"-time
476    (similar to the current exnHistory overhead), I have not yet
477    implemented this.  (The implementation will be rather easy.)  With
478    exceptions carrying back-trace information, this facility will be even
479    more useful because users don't need to modify their programs...
480    
481    - While it is possible to compile the compiler with back-trace
482    annotations turned on (I did it to get some confidence in
483    correctness), you must make absolutely sure that core.sml and
484    btimp.sml are compiled WITHOUT annotation!  (core.sml cannot actually
485    be compiled with annotation because there is no core access yet, but
486    if you compile btimp.sml with annotation, then the system will go into
487    an infinite recursion and crash.)
488    Since CM currently does not know about BTrace, the only way to turn
489    annotations on and off for different modules of the compiler is to
490    interrupt CMB.make, change the settings, and re-invoke it.  Of course,
491    this is awkward and clumsy.
492    
493    Sample sessions:
494    
495    Standard ML of New Jersey v110.28.1 [FLINT v1.5], June 5, 2000
496    - SMLofNJ.Internals.BTrace.mode (SOME true);
497    [autoloading]
498    [autoloading done]
499    val it = false : bool
500    - structure X = struct
501    -     fun main n = let
502    -         fun a (x, 0) = d x
503    -           | a (x, n) = b (x, n - 1)
504    -         and b (x, n) = c (x, n)
505    -         and c (x, n) = a (x, n)
506    -         and d x = e (x, 3)
507    -         and e (x, 0) = f x
508    -           | e (x, n) = e (x, n - 1)
509    -         and f 0 = SMLofNJ.Internals.BTrace.trigger ()
510    -           | f n = n * g (n - 1)
511    -         and g n = a (n, 3)
512    -     in
513    -         f n
514    -     end
515    - end;
516    structure X : sig val main : int -> int end
517    - X.main 3;
518    *** BACK-TRACE ***
519    GOTO   stdIn:4.2-13.20: X.main[2].f
520    GOTO-( stdIn:4.2-13.20: X.main[2].e
521    GOTO   stdIn:4.2-13.20: X.main[2].d
522         / stdIn:4.2-13.20: X.main[2].a
523         | stdIn:4.2-13.20: X.main[2].b
524    GOTO-\ stdIn:4.2-13.20: X.main[2].c
525    CALL   stdIn:4.2-13.20: X.main[2].g
526    GOTO   stdIn:4.2-13.20: X.main[2].f
527    GOTO-( stdIn:4.2-13.20: X.main[2].e
528    GOTO   stdIn:4.2-13.20: X.main[2].d
529         / stdIn:4.2-13.20: X.main[2].a
530         | stdIn:4.2-13.20: X.main[2].b
531    GOTO-\ stdIn:4.2-13.20: X.main[2].c
532    CALL   stdIn:4.2-13.20: X.main[2].g
533    GOTO   stdIn:4.2-13.20: X.main[2].f
534    GOTO-( stdIn:4.2-13.20: X.main[2].e
535    GOTO   stdIn:4.2-13.20: X.main[2].d
536         / stdIn:4.2-13.20: X.main[2].a
537         | stdIn:4.2-13.20: X.main[2].b
538    GOTO-\ stdIn:4.2-13.20: X.main[2].c
539    CALL   stdIn:4.2-13.20: X.main[2].g
540    GOTO   stdIn:4.2-13.20: X.main[2].f
541    CALL   stdIn:2.15-17.4: X.main[2]
542    -
543    
544    (Note that because of a FLINt bug the above code currently does not
545    compile without BTrace turned on.)
546    
547    Here is another example, using my modified Tiger compiler:
548    
549    Standard ML of New Jersey v110.28.1 [FLINT v1.5], June 5, 2000
550    - SMLofNJ.Internals.BTrace.mode (SOME true);
551    [autoloading]
552    [autoloading done]
553    val it = false : bool
554    - CM.make "sources.cm";
555    [autoloading]
556    ...
557    [autoloading done]
558    [scanning sources.cm]
559    [parsing (sources.cm):parse.sml]
560    [creating directory CM/SKEL ...]
561    [parsing (sources.cm):tiger.lex.sml]
562    ...
563    [wrote CM/sparc-unix/semant.sml]
564    [compiling (sources.cm):main.sml]
565    [wrote CM/sparc-unix/main.sml]
566    [New bindings added.]
567    val it = true : bool
568    - Main.compile ("../testcases/merge.tig", "foo.out");
569    *** BACK-TRACE ***
570    CALL   lib/semant.sml:99.2-396.21: SemantFun[2].transExp.trvar
571    CALL   lib/semant.sml:99.2-396.21: SemantFun[2].transExp.trexp
572    CALL   lib/semant.sml:289.3-295.22: SemantFun[2].transExp.trexp.check[2]
573    GOTO   lib/semant.sml:289.3-295.22: SemantFun[2].transExp.trexp.check[2]
574    CALL   lib/semant.sml:99.2-396.21: SemantFun[2].transExp.trexp
575    CALL   lib/semant.sml:99.2-396.21: SemantFun[2].transExp.trexp
576    CALL   lib/semant.sml:488.3-505.6: SemantFun[2].transDec.trdec[2].transBody[2]
577         / lib/semant.sml:411.65-543.8: SemantFun[2].transDec
578    CALL-\ lib/semant.sml:413.2-540.9: SemantFun[2].transDec.trdec[2]
579    CALL   lib/semant.sml:99.2-396.21: SemantFun[2].transExp.trexp
580    CALL   lib/semant.sml:8.52-558.4: SemantFun[2].transProg[2]
581    CALL   main.sml:1.18-118.4: Main.compile[2]
582    -
583    
584    ----------------------------------------------------------------------
585    Name: Matthias Blumen
586    Date: 2000/06/21 18:00:00 JST
587    Tag: blume-20000621-manual
588    Description:
589    
590    CM manual update: Path environments documented.
591    
592    ----------------------------------------------------------------------
593    Name: Matthias Blume
594    Date: 2000/06/19 13:40:00
595    Tag: blume-20000619-manual
596    Description:
597    
598    CM manual and system/README update.  This only covers the fact that
599    there are no more implicit anchors.  (Path environments and the "bind"
600    option to "cm" have yet to be documented.)
601    
602    ----------------------------------------------------------------------
603    Name: Matthias Blume
604    Date: 2000/06/19 11:05:00 JST
605    Tag: blume-20000619-chdir-bugfix
606    Description:
607    
608    Fixed a bug in new SrcPath module that sometimes led to a bad chDir call.
609    
610    ----------------------------------------------------------------------
611    Name: Matthias Blume
612    Date: 2000/06/18 22:00:10 JST
613    Tag: blume-20000618-implicit-anchors-really-gone
614    Description:
615    
616    I updates the previous HISTORY entry where I forgot to mention that
617    implicit anchors are no longer with us.
618    
619    The current update also gets rid of the (now useless) controller
620    CM.Control.implicit_anchors.
621    
622    ----------------------------------------------------------------------
623    Name: Matthias Blume
624    Date: 2000/06/16 17:30:00 JST
625    Tag: blume-20000616-anchorenv
626    Description:
627    
628    This patch implements the long anticipated (just kidding :) "anchor
629    environment" mechanism.  In the course of doing this, I also
630    re-implemented CM's internal "SrcPath" module from scratch.  The new
631    one should be more robust in certain boundary cases.  In any case, it
632    is a lot cleaner than its predecessor (IMHO).
633    
634    This time, although there is yet another boot file format change, I
635    kept the unpickler backward-compatible.  As a result, no new bootfiles
636    are necessary and bootstrapping is straightforward.  (You cannot read
637    new bootfiles into an old system, but the other way around is no
638    problem.)
639    
640    Visible changes:
641    
642    ** 0. Implicit path anchors (without the leading $-symbol) are no
643    longer recognized at all. This means that such path names are not
644    illegal either.  For example, the name basis.cm simply refers to a
645    local file called "basis.cm" (i.e, the name is an ordinary path
646    relative to .cm-files directory).  Or, to put it differently, only
647    names that start with $ are anchored paths.
648    
649    ** 1. The $<singlearc> abbreviation for $/<singlearc> has finally
650    vanished.
651    
652    John (Reppy) had critizised this as soon as I originally proposed and
653    implemented it, but at that time I did not really deeply believe
654    him. :) Now I came full-circle because I need the $<singlearc> syntax
655    in another place where it cannot be seen as an abbreviation for
656    $/<singlearc>.  To avoid the confusion, $<singlearc> now means what it
657    seems to mean (i.e., it "expands" into the corresponding anchor
658    value).
659    
660    However, when paths are used as members in CM description files, it
661    continues to be true that there must be at least another arc after the
662    anchor.  This is now enforced separately during semantic analysis
663    (i.e., from a lexical/syntactical point of view, the notation is ok.)
664    
665    ** 2. The "cm" class now accepts an option "bind".  The option's value
666    is a sub-option list of precisely two items -- one labeled "anchor"
667    and the other one labeled "value".  As you might expect, "anchor" is
668    used to specify an anchor name to be bound, and "value" specifies what
669    the anchor is being bound to.
670    
671    The value must be a directory name and can be given in either standard
672    syntax (including the possibility that it is itself an anchored path)
673    or native syntax.
674    
675    Examples:
676    
677       foo.cm (bind:(anchor:bar value:$mystuff/bar))
678       lib.cm (bind:(anchor:a value:"H:\\x\\y\\z"))  (* only works under windows *)
679    
680    and so on.
681    
682    The meaning of this is that the .cm-file will be processed with an
683    augmented anchor environment where the given anchor(s) is/are bound to
684    the given values(s).
685    
686    The rationale for having this feature is this: Suppose you are trying
687    to use two different (already stable) libraries a.cm and b.cm (that
688    you perhaps didn't write yourself).  Further, suppose each of these
689    two libraries internally uses its own auxiliary library $aux/lib.cm.
690    Normally you would now have a problem because the anchor "lib" can not
691    be bound to more than one value globally.  Therefore, the project that
692    uses both a.cm and b.cm must locally redirect the anchor to some other
693    place:
694    
695       a.cm (bind:(anchor:lib value:/usr/lib/smlnj/a-stuff))
696       b.cm (bind:(anchor:lib value:/usr/lib/smlnj/b-stuff))
697    
698    This hard-wires $lib/aux.cm to /usr/lib/smlnj/a-stuff/aux.cm or
699    /usr/lib/smlnj/b-stuff/aux.cm, respectively.
700    
701    Hard-wiring path names is a bit inflexible (and CM will verbosely warn
702    you when you do so at the time of CM.stabilize).  Therefore, you can
703    also use an anchored path as the value:
704    
705      a.cm (bind:(anchor:lib value:$a-lib))
706      b.cm (bind:(anchor:lib value:$b-lib))
707    
708    Now you can globally configure (using the usual CM.Anchor.anchor or
709    pathconfig machinery) bindings for "a-lib" and "b-lib".  Since "lib"
710    itself is always locally bound, setting it globally is no longer
711    meaningful or necessary (but it does not hurt either).  In fact, "lib"
712    can still be used as a global anchor for separate purposes.  As a
713    matter of fact, one can locally define "lib" in terms of a global
714    "lib":
715    
716      a.cm (bind:(anchor:lib value:$lib/a))
717      b.cm (bind:(anchor:lib value:$lib/b))
718    
719    ** 3: The encoding of path names has changed.  This affects the way
720    path names are shown in CM's progress report and also the internal
721    protocol encoding used for parallel make.
722    
723    The encoding now uses one or more ':'-separated segments.  Each
724    segments corresponds to a file that has been specified relative to the
725    file given by its preceding segment.  The first segment is either
726    relative to the CWD, absolute, or anchored.  Each segment itself is
727    basically a Unix pathname; all segments but the first are relative.
728    
729    Example:
730    
731       $foo/bar/baz.cm:a/b/c.sml
732    
733    This path denotes the file bar/a/b/c.sml relative to the directory
734    denoted by anchor "foo".  Notice that the encoding also includes
735    baz.cm which is the .cm-file that listed a/b/c.sml.  As usual, such
736    paths are resolved relative to the .cm-files directory, so baz.cm must
737    be ignored to get the "real" pathname.
738    
739    To make this fact more obvious, CM puts the names of such "virtual
740    arcs" into parentheses when they appear in progress reports. (No
741    parentheses will appear in the internal protocol encoding.)  Thus,
742    what you really see is:
743    
744      $foo/bar/(baz.cm):a/b/c.sml
745    
746    I find this notation to be much more informative than before.
747    
748    Another new feature of the encoding is that special characters
749    including parentheses, colons, (back)slashes, and white space are
750    written as \ddd (where ddd is the decimal encoding of the character).
751    
752    *** The CM manual still needs to be updated.
753    
754  ----------------------------------------------------------------------  ----------------------------------------------------------------------
755  Name: Allen Leung  Name: Allen Leung
756  Date: 2000/06/15 00:38:00  Date: 2000/06/15 00:38:00

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