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Diff of /sml/trunk/NOTES/HISTORY

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revision 1133, Tue Mar 12 03:56:23 2002 UTC revision 1184, Fri Mar 29 22:22:22 2002 UTC
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13  Description:  Description:
14    
15  ----------------------------------------------------------------------  ----------------------------------------------------------------------
16    Name: Matthias Blume
17    Date: 2002/03/29 17:22:00
18    Tag: blume-20020329-div
19    Description:
20    
21    Fixed my broken div/mod logic.  Unfortunately, this means that the
22    inline code for div/mod now has one more comparison than before.
23    Fast paths (quotient > 0 or remainder = 0) are not affected, though.
24    The problem was with quotient = 0, because that alone does not tell
25    us which way the rounding went.  One then has to look at whether
26    remainder and divisor have the same sign...  :(
27    
28    Anyway, I replaced the bootfiles with fresh ones...
29    
30    ----------------------------------------------------------------------
31    Name: Matthias Blume
32    Date: 2002/03/29 14:10:00 EST
33    Tag: blume-20020329-inlprims
34    Description:
35    
36    NEW BOOTFILES!!!    Version number bumped to 110.39.3.
37    
38    Primops have changed. This means that the bin/boot-file formats have
39    changed as well.
40    
41    To make sure that there is no confusion, I made a new version.
42    
43    
44    CHANGES:
45    
46    * removed REMT from mltree (remainder should never overflow).
47    
48    * added primops to deal with divisions of all flavors to the frontend
49    
50    * handled these primops all the way through so they map to their respective
51      MLRISC support
52    
53    * used these primops in the implementation of Int, Int32, Word, Word32
54    
55    * removed INLDIV, INLMOD, and INLREM as they are no longer necessary
56    
57    * parameterized INLMIN, INLMAX, and INLABS by a numkind
58    
59    * translate.sml now deals with all flavors of INL{MIN,MAX,ABS}, including
60      floating point
61    
62    * used INL{MIN,MAX,ABS} in the implementation of Int, Int32, Word, Word32,
63      and Real (but Real.abs maps to a separate floating-point-only primop)
64    
65    
66    TODO items:
67    
68    * Hacked Alpha32 instruction selection, disabling the selection of REMx
69      instructions because the machine instruction encoder cannot handle
70      them.  (Hppa, PPC, and Sparc instruction selection did not handle
71      REM in the first place, and REM is supported by the x86 machine coder.)
72    
73    * Handle DIV and MOD with DIV_TO_NEGINF directly in the x86 instruction
74      selection phase.  (The two can be streamlined because the hardware
75      delivers both quotient and remainder at the same time anyway.)
76    
77    * Think about what to do with "valOf(Int32.minInt) div ~1" and friends.
78      (Currently the behavior is inconsistent both across architectures and
79      wrt. the draft Basis spec.)
80    
81    * Word8 should eventually be handled natively, too.
82    
83    * There seems to be one serious bug in mltree-gen.sml.  It appears, though,
84      as if there currently is no execution path that could trigger it in
85      SML/NJ.  (The assumptions underlying functions arith and promotable do not
86      hold for things like multiplication and division.)
87    
88    ----------------------------------------------------------------------
89    Name: Matthias Blume
90    Date: 2002/03/27 16:27:00 EST
91    Tag: blume-20020327-mlrisc-divisions
92    Description:
93    
94    Added support for all four division operations (ML's div, mod, quot,
95    and rem) to MLRISC.  In the course of doing so, I also rationalized
96    the naming (no more annoying switch-around of DIV and QUOT), by
97    parameterizing the operation by div_rounding_mode (which can be either
98    DIV_TO_ZERO or DIV_TO_NEGINF).
99    
100    The generic MLTreeGen functor takes care of compiling all four
101    operations down to only round-to-zero div.
102    
103    Missing pieces:
104    
105      * Doing something smarter than relying on MLTreeGen on architectures
106        like, e.g., the x86 where hardware division delivers both quotient and
107        remainder at the same time.  With this, the implementation of the
108        round-to-neginf operations could be further streamlined.
109    
110      * Remove inlining support for div/mod/rem from the frontend and replace it
111        with primops that get carried through to the backend.  Do this for all
112        int and word types.
113    
114    ----------------------------------------------------------------------
115    Name: Matthias Blume
116    Date: 2002/03/25 17:25:00 EST
117    Tag: blume-20020325-divmod
118    Description:
119    
120    I improved (hopefully without breaking them) the implementation of Int.div,
121    Int.mod, and Int.rem.   For this, the code in translate.sml now takes
122    advantage of the following observations:
123    
124      Let  q = x quot y      r = x rem y
125           d = x div  y      m = x mod y
126    
127    where "quot" is the round-to-zero version of integer division that
128    hardware usually provides.  Then we have:
129    
130         r = x - q * y        where neither the * nor the - will overflow
131         d = if q >= 0 orelse x = q * y then q else q - 1
132                              where neither the * nor the - will overflow
133         m = if q >= 0 orelse r = 0 then r else r + y
134                              where the + will not overflow
135    
136    This results in substantial simplification of the generated code.
137    The following table shows the number of CFG nodes and edges generated
138    for
139            fun f (x, y) = x OPER y
140            (* with OPER \in div, mod, quot, rem *)
141    
142    
143        OPER | nodes(old) | edges(old) | nodes(new) | edges(new)
144        --------------------------------------------------------
145         div |         24 |         39 |         12 |         16
146         mod |         41 |         71 |         12 |         16
147        quot |          8 |         10 |          8 |         10
148         rem |         10 |         14 |          8 |         10
149    
150    
151    ----------------------------------------------------------------------
152    Name: Matthias Blume
153    Date: 2002/03/25 22:06:00 EST
154    Tag: blume-20020325-cprotobug
155    Description:
156    
157    Fixed a bug in cproto (c prototype decoder).
158    
159    ----------------------------------------------------------------------
160    Name: Matthias Blume
161    Date: 2002/03/25 16:00:00 EST
162    Tag: blume-20020325-raw-primops
163    Description:
164    
165    I did some cleanup to Allen's new primop code and
166    replaced yesterday's bootfiles with new ones.
167    (But they are stored in the same place.)
168    
169    ----------------------------------------------------------------------
170    Name: Matthias Blume
171    Date: 2002/03/24 22:40:00 EST
172    Tag: blume-20020324-bootfiles
173    Description:
174    
175    Made the bootfiles that Allen asked for.
176    
177    ----------------------------------------------------------------------
178    Name: Allen Leung
179    Date: 2002/03/23 15:50:00 EST
180    Tag: leunga-20020323-flint-cps-rcc-primops
181    Description:
182    
183      1. Changes to FLINT primops:
184    
185        (* make a call to a C-function;
186         * The primop carries C function prototype information and specifies
187         * which of its (ML-) arguments are floating point. C prototype
188         * information is for use by the backend, ML information is for
189         * use by the CPS converter. *)
190      | RAW_CCALL of { c_proto: CTypes.c_proto,
191                       ml_args: ccall_type list,
192                       ml_res_opt: ccall_type option,
193                       reentrant : bool
194                     } option
195       (* Allocate uninitialized storage on the heap.
196        * The record is meant to hold short-lived C objects, i.e., they
197        * are not ML pointers.  With the tag, the representation is
198        * the same as RECORD with tag tag_raw32 (sz=4), or tag_fblock (sz=8)
199        *)
200      | RAW_RECORD of {tag:bool,sz:int}
201      and ccall_type = CCALL_INT32 | CCALL_REAL64 | CCALL_ML_PTR
202    
203      2.  These CPS primops are now overloaded:
204    
205           rawload of {kind:numkind}
206           rawstore of {kind:numkind}
207    
208          The one argument form is:
209    
210             rawload {kind} address
211    
212          The two argument form is:
213    
214             rawload {kind} [ml object, byte-offset]
215    
216      3. RAW_CCALL/RCC now takes two extra arguments:
217    
218         a. The first is whether the C call is reentrant, i.e., whether
219            ML state should be saved and restored.
220         b. The second argument is a string argument specifying the name of
221            library and the C function.
222    
223         These things are currently not handled in the code generator, yet.
224    
225      4. In CProto,
226    
227         An encoding type of "bool" means "ml object" and is mapped into
228         C prototype of PTR.  Note that "bool" is different than "string",
229         even though "string" is also mapped into PTR, because "bool"
230         is assigned an CPS type of BOGt, while "string" is assigned INT32t.
231    
232      5. Pickler/unpicker
233    
234         Changed to handle RAW_RECORD and newest RAW_CCALL
235    
236      6. MLRiscGen,
237    
238         1. Changed to handle the new rawload/rawstore/rawrecord operators.
239         2. Code for handling C Calls has been moved to a new module CPSCCalls,
240            in the file CodeGen/cpscompile/cps-c-calls.sml
241    
242      7. Added the conditional move operator
243    
244             condmove of branch
245    
246         to cps.  Generation of this is still buggy so it is currently
247         disabled.
248    
249    ----------------------------------------------------------------------
250    Name: Lal George
251    Date: 2002/03/22 14:18:25 EST
252    Tag: george-20020322-cps-branch-prob
253    Description:
254    
255    Implemented the Ball-Larus branch prediction-heuristics, and
256    incorporated graphical viewers for control flow graphs.
257    
258    Ball-Larus Heuristics:
259    ---------------------
260    See the file compiler/CodeGen/cpscompile/cpsBranchProb.sml.
261    
262    By design it uses the Dempster-Shafer theory for combining
263    probabilities.  For example, in the function:
264    
265        fun f(n,acc) = if n = 0 then acc else f(n-1, n*acc)
266    
267    the ball-larus heuristics predicts that the n=0 is unlikely
268    (OH-heuristic), and the 'then' branch is unlikely because of the
269    RH-heuristic -- giving the 'then' branch an even lower combined
270    probability using the Dempster-Shafer theory.
271    
272    Finally, John Reppy's loop analysis in MLRISC, further lowers the
273    probability of the 'then' branch because of the loop in the else
274    branch.
275    
276    
277    Graphical Viewing:
278    ------------------
279    I merely plugged in Allen's graphical viewers into the compiler. The
280    additional code is not much. At the top level, saying:
281    
282            Control.MLRISC.getFlag "cfg-graphical-view" := true;
283    
284    will display the graphical view of the control flow graph just before
285    back-patching.  daVinci must be in your path for this to work. If
286    daVinci is not available, then the default viewer can be changed
287    using:
288    
289            Control.MLRISC.getString "viewer"
290    
291    which can be set to "dot" or "vcg" for the corresponding viewers. Of
292    course, these viewers must be in your path.
293    
294    The above will display the compilation unit at the level of clusters,
295    many of which are small, boring, and un-interesting. Also setting:
296    
297            Control.MLRISC.getInt "cfg-graphical-view_size"
298    
299    will display clusters that are larger than the value set by the above.
300    
301    
302    ----------------------------------------------------------------------
303    Name: Matthias Blume
304    Date: 2002/03/21 22:20:00 EST
305    Tag: blume-20020321-kmp-bugfix
306    Description:
307    
308    Changed the interface to the KMP routine in PreString and fixed
309    a minor bug in one place where it was used.
310    
311    ----------------------------------------------------------------------
312    Name: Allen Leung
313    Date: 2002/03/21 20:30:00 EST
314    Tag: leunga-20020321-cfg
315    Description:
316    
317      Fixed a potential problem in cfg edge splitting.
318    
319    ----------------------------------------------------------------------
320    Name: Allen Leung
321    Date: 2002/03/21 17:15:00 EST
322    Tag: leunga-20020321-x86-fp-cfg
323    Description:
324    
325      1. Recoded the buggy parts of x86-fp.
326    
327         a. All the block reordering code has been removed.
328            We now depend on the block placement phases to do this work.
329    
330         b. Critical edge splitting code has been simplified and moved into the
331            CFG modules, as where they belong.
332    
333         Both of these were quite buggy and complex.  The code is now much, much
334         simpler.
335    
336      2. X86 backend.
337    
338         a. Added instructions for 64-bit support.  Instruction selection for
339            64-bit has not been committed, however, since that
340            requires changes to MLTREE which haven't been approved by
341            Lal and John.
342    
343         b. Added support for FUCOMI and FUCOMIP when generating code for
344            PentiumPro and above.  We only generate these instructions in
345            the fast-fp mode.
346    
347         c. Added cases for JP and JNP in X86FreqProps.
348    
349      3. CFG
350    
351         CFG now has a bunch of methods for edge splitting and merging.
352    
353      4. Machine description.
354    
355         John's simplification of MLTREE_BASIS.fcond broke a few machine
356         description things:
357    
358         rtl-build.{sig,sml} and hppa.mdl fixed.
359    
360         NOTE: the machine description stuff in the repository is still broken.
361               Again, I can't put my fixes in because that involves
362               changes to MLTREE.
363    
364    ----------------------------------------------------------------------
365    Name: Matthias Blume
366    Date: 2002/03/20 15:55:00 EST
367    Tag: blume-20020320-kmp
368    Description:
369    
370    Implemented Knuth-Morris-Pratt string matching in PreString and used
371    it for String.isSubstring, Substring.isSubstring, and
372    Substring.position.
373    
374    (Might need some stress-testing.  Simple examples worked fine.)
375    
376    ----------------------------------------------------------------------
377    Name: Matthias Blume
378    Date: 2002/03/19 16:37:00 EST
379    Tag: blume-20020319-witnesses
380    Description:
381    
382    Added a structure C.W and functions convert/Ptr.convert to ml-nlffi-lib.
383    
384    This implements a generic mechanism for changing constness qualifiers
385    anywhere within big C types without resorting to outright "casts".
386    (So far, functions such as C.rw/C.ro or C.Ptr.rw/C.Ptr.ro only let you
387    modify the constness at the outermost level.)
388    The implementation of "convert" is based on the idea of "witness"
389    values -- values that are not used by the operation but whose types
390    "testify" to their applicability.  On the implementation side, "convert"
391    is simply a projection (returning its second curried argument).  With
392    cross-module inlining, it should not result in any machine code being
393    generated.
394    
395    ----------------------------------------------------------------------
396    Name: Matthias Blume
397    Date: 2002/03/15 16:40:00 EST
398    Tag: blume-20020315-basis
399    Description:
400    
401    Provided (preliminary?) implementations for
402    
403      {String,Substring}.{concatWith,isSuffix,isSubstring}
404    
405    and
406    
407      Substring.full
408    
409    Those are in the Basis spec but they were missing in SML/NJ.
410    
411    ----------------------------------------------------------------------
412    Name: Matthias Blume
413    Date: 2002/03/14 21:30:00 EST
414    Tag: blume-20020314-controls
415    Description:
416    
417    Controls:
418    ---------
419    
420    1. Factored out the recently-added Controls : CONTROLS stuff and put
421       it into its own library $/controls-lib.cm.  The source tree for
422       this is under src/smlnj-lib/Controls.
423    
424    2. Changed the names of types and functions in this interface, so they
425       make a bit more "sense":
426    
427          module -> registry
428          'a registry -> 'a group
429    
430    3. The interface now deals in ref cells only.  The getter/setter interface
431       is (mostly) gone.
432    
433    4. Added a function that lets one register an already-existing ref cell.
434    
435    5. Made the corresponding modifications to the rest of the code so that
436       everything compiles again.
437    
438    6. Changed the implementation of Controls.MLRISC back to something closer
439       to the original.  In particular, this module (and therefore MLRISC)
440       does not depend on Controls.  There now is some link-time code in
441       int-sys.sml that registers the MLRISC controls with the Controls
442       module.
443    
444    CM:
445    ---
446    
447      * One can now specify the lambda-split aggressiveness in init.cmi.
448    
449    ----------------------------------------------------------------------
450    Name: Allen Leung
451    Date: 2002/03/13 17:30:00 EST
452    Tag: leunga-20020313-x86-fp-unary
453    Description:
454    
455    Bug fix for:
456    
457    > leunga@weaselbane:~/Yale/tmp/sml-dist{21} bin/sml
458    > Standard ML of New Jersey v110.39.1 [FLINT v1.5], March 08, 2002
459    > - fun f(x,(y,z)) = Real.~ y;
460    > [autoloading]
461    > [autoloading done]
462    >       fchsl   (%eax), 184(%esp)
463    > Error: MLRisc bug: X86MCEmitter.emitInstr
464    >
465    > uncaught exception Error
466    >   raised at: ../MLRISC/control/mlriscErrormsg.sml:16.14-16.19
467    
468    The problem was that the code generator did not generate any fp registers
469    in this case, and the ra didn't know that it needed to run the X86FP phase to
470    translate the pseudo fp instruction.   This only happened with unary fp
471    operators in certain situations.
472    
473    ----------------------------------------------------------------------
474    Name: Matthias Blume
475    Date: 2002/03/13 14:00:00 EST
476    Tag: blume-20020313-overload-etc
477    Description:
478    
479    1. Added _overload as a synonym for overload for backward compatibility.
480       (Control.overloadKW must be true for either version to be accepted.)
481    
482    2. Fixed bug in install script that caused more things to be installed
483       than what was requested in config/targets.
484    
485    3. Made CM aware of the (_)overload construct so that autoloading
486       works.
487    
488    ----------------------------------------------------------------------
489    Name: Matthias Blume
490    Date: 2002/03/12 22:03:00 EST
491    Tag: blume-20020312-url
492    Description:
493    
494    Forgot to update BOOT and srcarchiveurl.
495    
496    ----------------------------------------------------------------------
497    Name: Matthias Blume
498    Date: 2002/03/12 17:30:00 EST
499    Tag: blume-20020312-version110392
500    Description:
501    
502    Yet another version number bump (because of small changes to the
503    binfile format).  Version number is now 110.39.2.  NEW BOOTFILES!
504    
505    Changes:
506    
507      The new pid generation scheme described a few weeks ago was overly
508      complicated.  I implemented a new mechanism that is simpler and
509      provides a bit more "stability":  Once CM has seen a compilation
510      unit, it keeps its identity constant (as long as you do not delete
511      those crucial CM/GUID/* files).  This means that when you change
512      an interface, compile, then go back to the old interface, and
513      compile again, you arrive at the original pid.
514    
515      There now also is a mechanism that instructs CM to use the plain
516      environment hash as a module's pid (effectively making its GUID
517      the empty string).  For this, "noguid" must be specified as an
518      option to the .sml file in question within its .cm file.
519      This is most useful for code that is being generated by tools such
520      as ml-nlffigen (because during development programmers tend to
521      erase the tool's entire output directory tree including CM's cached
522      GUIDs).  "noguid" is somewhat dangerous (since it can be used to locally
523      revert to the old, broken behavior of SML/NJ, but in specific cases
524      where there is no danger of interface confusion, its use is ok
525      (I think).
526    
527      ml-nlffigen by default generates "noguid" annotations.  They can be
528      turned off by specifying -guid in its command line.
529    
530    ----------------------------------------------------------------------
531    Name: Lal George
532    Date: 2002/03/12 12 14:42:36 EST
533    Tag: george-20020312-frequency-computation
534    Description:
535    
536    Integrated jump chaining and static block frequency into the
537    compiler. More details and numbers later.
538    
539    ----------------------------------------------------------------------
540  Name: Lal George  Name: Lal George
541  Date: 2002/03/11 11 22:38:53 EST  Date: 2002/03/11 11 22:38:53 EST
542  Tag: george-20020311-jump-chain-elim  Tag: george-20020311-jump-chain-elim
# Line 60  Line 584 
584  ----------------------------------------------------------------------  ----------------------------------------------------------------------
585  Name: Allen Leung  Name: Allen Leung
586  Date: 2002/03/11 10:30:00 EST  Date: 2002/03/11 10:30:00 EST
587  Tag: leunga-20020310-runtime-string0  Tag: leunga-20020311-runtime-string0
588  Description:  Description:
589    
590     The representation of the empty string now points to a     The representation of the empty string now points to a

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