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Re: [tree-ssa] RFC: Making control flow more explicit


Hello,

>  >>  >because parent obviously is not what you want here. IIRC in the ssa dce
>  >>  >algorithm marking of the neccesary control statements is somehow
>  >>  >done using dominator information.
>  >> The RTL version does use dominator information, the tree version does not
>  >> use dominator information to find necessary control statements.
>  >>
>  >> The tree version uses the nested control structure and goto following to
>  >> deduce control dependency.
>  >
>  >The question is, do we eventually somewhen will need postdoms anyway?
> Very very rarely within the DCE optimizer.

if I understand the code correctly, only when some control statement is
actually removed. This together with your claim that it occurs rarely
implies that the optimization is almost useless in practice.  Would not
it then make sense to perform it only with -O3, then the extra time
for computing postdominators would be more acceptable?

Zdenek


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