On Mon, Nov 29, 2021 at 6:20 PM Andrew MacLeod via Gcc-patches <gcc-patches@gcc.gnu.org> wrote: > > I need to adjust the original patch, I shouldn't have continued the loop > when dealing with equivalences. An equivalence is not the same as an > undefined value... we might be able to ignore the range from it for > calculation purposes, but we cannot ignore the fact that it is a > different SSA_NAME and may contain a different value that we do care about. > > There are other checks in then loop which will allow us to assign an > equivalence between the DEF and an argument if we are ignoring the other > ssa_names.. such as when there are undefined values. > > a_3 = PHI <a_1(4), a_2(6)> > > if a_2 is undefined, we can create an equivalence between a_3 and a_1 as > the value of a_2 is irrelevant and can be whatever we want it to be. > > if a_2 is instead an equivalence with a_3, we do not want to create an > equivalence between a_3 and a_1 in this block as we may then turn it > into a copy.. we'd only be able to do this if there was an equivalence > between a_1 and a_2, and we are not checking that. > > Although we are may not be adding the range for a_2 into the cumulative > knowledge of a_3's range, we do need to keep the edge to retain the copy > as its value is important and could be different than the other > argument... and we need to retain the copy when we go out of ssa. > > This fixes that oversight, bootstrapped on x86_64-pc-linux-gnu with no > regressions. OK?
OK. > Caveat.. the test case has an infinite loop without this fix, but > degagnu doesn't seem to kill it, and my test suite runs go forever.. if > there something I am missing? The gcc.log claims that it timeouts > after 300 second, but it doesn't kill the executable. I set the > dg-timeout field, but that appears to be a compile time timeout, not > runtime anyway. Might be an old issue with your dejagnu, it should work. Richard. > > Andrew
