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Diff of /sml/trunk/NOTES/HISTORY

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revision 1159, Fri Mar 22 03:18:24 2002 UTC revision 1168, Fri Mar 22 19:19:32 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: blume-20020321-cps-branch-prob
19    Description:
20    
21    Implemented the Ball-Larus branch prediction-heuristic, and
22    incorporated graphical viewers for control flow graphs.
23    
24    Ball-Larus Heuristic:
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-Shater 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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