EQNTOTT-Specific Optimizations

I received several requests for additional information regarding
EQNTOTT-Specific optimizations and pattern matching, and have codified
several tests which exhibit these issues and defects.


Some compilers use EQNTOTT-specific optimizations to achieve the best
possible run-time performance. Examples include compilers that


1) Generate exceptionally good code for EQNTOTT, but generate poor code
      for programs that are only slightly different from EQNTOTT; and,
2) Generate EQNTOTT code for programs that are very similar to EQNTOTT
      but are not semantically equivalent.


A more complete description is available at
http://www.nullstone.com/eqntott/eqntott.htm.


The sources for the test files that exhibit these optimizations and
defects are available at
ftp://www.nullstone.com/pub/eqntott-tests.tar.Z.


Although EQNTOTT has not been included in SPEC95, the issues relating
to benchmark-specific optimizations, and in particular, which
optimizations should be allowed when reporting SPEC results, is still
the subject of debate.


Best regards,
Christopher Glaeser cdg@nullstone.com
Nullstone Corporation http://www.nullstone.com


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