Diff of /sml/branches/primop-branch-3/NOTES/HISTORY

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	revision 1148, Fri Mar 15 21:38:57 2002 UTC	revision 1171, Fri Mar 22 20:41:43 2002 UTC
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13	Description:	Description:
14
15	----------------------------------------------------------------------	----------------------------------------------------------------------
16		Name: Lal George
17		Date: 2002/03/22 14:18:25 EST
18		Tag: george-20020322-cps-branch-prob
19		Description:
20
21		Implemented the Ball-Larus branch prediction-heuristics, and
22		incorporated graphical viewers for control flow graphs.
23
24		Ball-Larus Heuristics:
25		---------------------
26		See the file compiler/CodeGen/cpscompile/cpsBranchProb.sml.
27
28		By design it uses the Dempster-Shafer theory for combining
29		probabilities.  For example, in the function:
30
31		fun f(n,acc) = if n = 0 then acc else f(n-1, n*acc)
32
33		the ball-larus heuristics predicts that the n=0 is unlikely
34		(OH-heuristic), and the 'then' branch is unlikely because of the
35		RH-heuristic -- giving the 'then' branch an even lower combined
36		probability using the Dempster-Shafer theory.
37
38		Finally, John Reppy's loop analysis in MLRISC, further lowers the
39		probability of the 'then' branch because of the loop in the else
40		branch.
41
42
43		Graphical Viewing:
44		------------------
45		I merely plugged in Allen's graphical viewers into the compiler. The
46		additional code is not much. At the top level, saying:
47
48		Control.MLRISC.getFlag "cfg-graphical-view" := true;
49
50		will display the graphical view of the control flow graph just before
51		back-patching.  daVinci must be in your path for this to work. If
52		daVinci is not available, then the default viewer can be changed
53		using:
54
55		Control.MLRISC.getString "viewer"
56
57		which can be set to "dot" or "vcg" for the corresponding viewers. Of
58		course, these viewers must be in your path.
59
60		The above will display the compilation unit at the level of clusters,
61		many of which are small, boring, and un-interesting. Also setting:
62
63		Control.MLRISC.getInt "cfg-graphical-view_size"
64
65		will display clusters that are larger than the value set by the above.
66
67
68		----------------------------------------------------------------------
69		Name: Matthias Blume
70		Date: 2002/03/21 22:20:00 EST
71		Tag: blume-20020321-kmp-bugfix
72		Description:
73
74		Changed the interface to the KMP routine in PreString and fixed
75		a minor bug in one place where it was used.
76
77		----------------------------------------------------------------------
78		Name: Allen Leung
79		Date: 2002/03/21 20:30:00 EST
80		Tag: leunga-20020321-cfg
81		Description:
82
83		Fixed a potential problem in cfg edge splitting.
84
85		----------------------------------------------------------------------
86		Name: Allen Leung
87		Date: 2002/03/21 17:15:00 EST
88		Tag: leunga-20020321-x86-fp-cfg
89		Description:
90
91		1. Recoded the buggy parts of x86-fp.
92
93		a. All the block reordering code has been removed.
94		We now depend on the block placement phases to do this work.
95
96		b. Critical edge splitting code has been simplified and moved into the
97		CFG modules, as where they belong.
98
99		Both of these were quite buggy and complex.  The code is now much, much
100		simpler.
101
102		2. X86 backend.
103
104		a. Added instructions for 64-bit support.  Instruction selection for
105		64-bit has not been committed, however, since that
106		requires changes to MLTREE which haven't been approved by
107		Lal and John.
108
109		b. Added support for FUCOMI and FUCOMIP when generating code for
110		PentiumPro and above.  We only generate these instructions in
111		the fast-fp mode.
112
113		c. Added cases for JP and JNP in X86FreqProps.
114
115		3. CFG
116
117		CFG now has a bunch of methods for edge splitting and merging.
118
119		4. Machine description.
120
121		John's simplification of MLTREE_BASIS.fcond broke a few machine
122		description things:
123
124		rtl-build.{sig,sml} and hppa.mdl fixed.
125
126		NOTE: the machine description stuff in the repository is still broken.
127		Again, I can't put my fixes in because that involves
128		changes to MLTREE.
129
130		----------------------------------------------------------------------
131		Name: Matthias Blume
132		Date: 2002/03/20 15:55:00 EST
133		Tag: blume-20020320-kmp
134		Description:
135
136		Implemented Knuth-Morris-Pratt string matching in PreString and used
137		it for String.isSubstring, Substring.isSubstring, and
138		Substring.position.
139
140		(Might need some stress-testing.  Simple examples worked fine.)
141
142		----------------------------------------------------------------------
143		Name: Matthias Blume
144		Date: 2002/03/19 16:37:00 EST
145		Tag: blume-20020319-witnesses
146		Description:
147
148		Added a structure C.W and functions convert/Ptr.convert to ml-nlffi-lib.
149
150		This implements a generic mechanism for changing constness qualifiers
151		anywhere within big C types without resorting to outright "casts".
152		(So far, functions such as C.rw/C.ro or C.Ptr.rw/C.Ptr.ro only let you
153		modify the constness at the outermost level.)
154		The implementation of "convert" is based on the idea of "witness"
155		values -- values that are not used by the operation but whose types
156		"testify" to their applicability.  On the implementation side, "convert"
157		is simply a projection (returning its second curried argument).  With
158		cross-module inlining, it should not result in any machine code being
159		generated.
160
161		----------------------------------------------------------------------
162	Name: Matthias Blume	Name: Matthias Blume
163	Date: 2002/03/15 16:40:00 EST	Date: 2002/03/15 16:40:00 EST
164	Tag: blume-20020315-basis	Tag: blume-20020315-basis

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