[Bug tree-optimization/31849] [4.3 Regression] Code size regression caused by fix to PR 31360

rakdver at gcc dot gnu dot org gcc-bugzilla@gcc.gnu.org
Sat Nov 24 19:08:00 GMT 2007



------- Comment #20 from rakdver at gcc dot gnu dot org  2007-11-24 19:08 -------

> Couldn't ivopts be taught to recognize "dec and branch on zero" patterns
> 
>   k_114 = k_15 + -1;
>   if (k_114 != 0)
>     goto <bb 10>;
>   else
>     goto <bb 11>;
> 
> and take into account their breakage for its cost estimates somehow?

Why?  If using dec and branch is profitable, doloop pass should do it; the
transformation that ivopts do does not prevent that or make it any more
difficult.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31849



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