[PATCH 2/2] shrink-wrap: Rewrite try_shrink_wrapping

Bernd Schmidt bschmidt@redhat.com
Fri Sep 11 13:11:00 GMT 2015


On 09/11/2015 02:36 PM, Segher Boessenkool wrote:

>> I'm wondering how your new algorithm prevents the prologue from being
>> placed inside a loop. Can you have a situation where this picks a
>> predecessor that is reachable but not dominated by PRO?
>
> It doesn't prevent it!
>
> The prologue will not be _inside_ the loop: there is one prologue, and it
> is executed exactly once for any block needing it.  But the code can copy
> part of the first iteration of a loop, if there are early exits.  Example
> (from the testsuite, pr39943.c, -Os I think):

I was wondering if that was the intention. This also ought to be spelled 
out in the comments.


Bernd



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