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revision 1168, Fri Mar 22 19:19:32 2002 UTC revision 1184, Fri Mar 29 22:22:22 2002 UTC
# Line 13  Line 13 
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  Name: Lal George
251  Date: 2002/03/22 14:18:25 EST  Date: 2002/03/22 14:18:25 EST
252  Tag: blume-20020321-cps-branch-prob  Tag: george-20020322-cps-branch-prob
253  Description:  Description:
254    
255  Implemented the Ball-Larus branch prediction-heuristic, and  Implemented the Ball-Larus branch prediction-heuristics, and
256  incorporated graphical viewers for control flow graphs.  incorporated graphical viewers for control flow graphs.
257    
258  Ball-Larus Heuristic:  Ball-Larus Heuristics:
259  ---------------------  ---------------------
260  See the file compiler/CodeGen/cpscompile/cpsBranchProb.sml.  See the file compiler/CodeGen/cpscompile/cpsBranchProb.sml.
261    
# Line 33  Line 267 
267  the ball-larus heuristics predicts that the n=0 is unlikely  the ball-larus heuristics predicts that the n=0 is unlikely
268  (OH-heuristic), and the 'then' branch is unlikely because of the  (OH-heuristic), and the 'then' branch is unlikely because of the
269  RH-heuristic -- giving the 'then' branch an even lower combined  RH-heuristic -- giving the 'then' branch an even lower combined
270  probability using the Dempster-Shater theory.  probability using the Dempster-Shafer theory.
271    
272  Finally, John Reppy's loop analysis in MLRISC, further lowers the  Finally, John Reppy's loop analysis in MLRISC, further lowers the
273  probability of the 'then' branch because of the loop in the else  probability of the 'then' branch because of the loop in the else

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