[Bug rtl-optimization/19210] [4.0 Regression] not using do-loop for some loops

dje at gcc dot gnu dot org gcc-bugzilla@gcc.gnu.org
Fri Dec 31 23:55:00 GMT 2004


------- Additional Comments From dje at gcc dot gnu dot org  2004-12-31 23:55 -------
XLC includes the option

          strict_induction
                      Turns off induction variable optimizations
                      that have the potential to alter the semantics of a
                      user's program. The default is "nostrict_induction" at
                      -O2 or higher and "strict_induction" otherwise.
                      "nostrict_induction" is recomended if your program does
                      not have overflows or wrap arounds of loop induction
                      variables.

We probably need something similar in GCC.  Note that XLC enables it when
optimizing.

Most programmers do not expect to be limited by the undefined wrapping behavior.
   They are not using the extremes.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19210



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