------- Comment #26 from rakdver at kam dot mff dot cuni dot cz 2010-07-07
11:19 -------
Subject: Re: [4.6 regression] RTL loop
unrolling causes FAIL: gcc.dg/pr39794.c
> In
>
> ...
> *p_1 = x;
> y = *(p_1 + 1);
> ...
>
> I can say that *p_1 does not alias *(p_1 + 1) independent on what code
> is around. If it would be
>
> BB3:
> # p_1 = PHI <p_0, p_2(3)>
> *p_1 = x;
> y = *(p_1 + 1);
> p_2 = p_1 + 1;
> goto BB3;
>
> that would be still correct (I can exchange those two statements).
Well, yes. Still, I would like to hear your formal definition of what it means
for two memory references (not to) alias. We certainly can modify the code to
ensure such a property, but just toying around without knowing precisely what
this property is definitely is not a good idea.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44838
