------- Additional Comments From kazu at cs dot umass dot edu 2004-12-10 19:57 ------- Subject: Re: [4.0 regression] loop miscompilation at -O1 (-ftree-ch)
Hi Jeff, > > I think so. :-) > I don't. :( I think it'll record tmp_1 = next_2, which is actually > wrong, even though it doesn't actually cause problems with this > testcase. IMHO, you should really think of it as tmp_1 -> next_2 or "tmp_1 is a copy-of next_2". It is a one-way relation, not an equivalence because it is not symmetric. In other words, tmp_1 -> next_2 (or SSA_NAME_VALUE (tmp_1) == next_2) means that tmp_1 should be replaced with next_2 if you were moving a statement in E->dest to E->src. The other direction does not hold because next_2 should *not* be replaced with tmp_1. It should be replaced with 0 instead. Let me also think hard to see if I can prove my patch is correct or come up with a counterexample. I certainly don't intend to push my patch blindly. Oh, by the way, let's wait on putting the testcase. I am pretty sure people will complain about a "regression" in their test results. Kazu Hirata -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18694 ------- You are receiving this mail because: ------- You are on the CC list for the bug, or are watching someone who is.
