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[smlnj] Diff of /sml/trunk/NOTES/HISTORY
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Diff of /sml/trunk/NOTES/HISTORY

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revision 1132, Mon Mar 11 18:32:50 2002 UTC revision 1133, Tue Mar 12 03:56:23 2002 UTC
# Line 13  Line 13 
13  Description:  Description:
14    
15  ----------------------------------------------------------------------  ----------------------------------------------------------------------
16    Name: Lal George
17    Date: 2002/03/11 11 22:38:53 EST
18    Tag: george-20020311-jump-chain-elim
19    Description:
20    
21    Tested the jump chain elimination on all architectures (except the
22    hppa).  This is on by default right now and is profitable for the
23    alpha and x86, however, it may not be profitable for the sparc and ppc
24    when compiling the compiler.
25    
26    The gc test will typically jump to a label at the end of the cluster,
27    where there is another jump to an external cluster containing the actual
28    code to invoke gc. This is to allow factoring of common gc invocation
29    sequences. That is to say, we generate:
30    
31            f:
32               testgc
33               ja   L1      % jump if above to L1
34    
35            L1:
36               jmp L2
37    
38    
39    After jump chain elimination the 'ja L1' instructions is converted to
40    'ja L2'. On the sparc and ppc, many of the 'ja L2' instructions may end
41    up being implemented in their long form (if L2 is far away) using:
42    
43            jbe     L3      % jump if below or equal to L3
44            jmp     L2
45         L3:
46            ...
47    
48    
49    For large compilation units L2  may be far away.
50    
51    
52    ----------------------------------------------------------------------
53  Name: Matthias Blume  Name: Matthias Blume
54  Date: 2002/03/11 13:30:00 EST  Date: 2002/03/11 13:30:00 EST
55  Tag: blume-20020311-mltreeeval  Tag: blume-20020311-mltreeeval

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