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

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	revision 1159, Fri Mar 22 03:18:24 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	Name: Matthias Blume
70	Date: 2002/03/21 22:20:00 EST	Date: 2002/03/21 22:20:00 EST
71	Tag: blume-20020321-kmp-bugfix	Tag: blume-20020321-kmp-bugfix

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