Re: [tree-ssa vs lno] who is right?

[law@redhat.com]

In message <1080264779.4600.25.camel@localhost.localdomain>, Diego Novillo writ
es:
 >On Thu, 2004-03-25 at 20:29, Dale Johannesen wrote:
 >
 >> ;; basic block 19, loop depth 0, count 0
 >> ;; prev block 9, next block 20
 >> ;; pred:       10 [100.0%]  (fallthru)
 >> ;; succ:       28 [50.0%]  (true,exec) 29 [50.0%]  (false,exec)
 >> # maxmin_Result_140 = PHI <1(10)>;
 >> # maxmin_Result_142 = PHI <2(10)>;
 >> # lsm_tmp.19_144 = PHI <lsm_tmp.19_84(10)>;
 >> <L28>:;
 >> if (m__10 == 0) goto <L26>; else goto <L27>;
 >> 
 >> Is that suppose to be a valid assumption?  The dup is created by 
 >> copyrename, and
 >> I see no code there that's intended to stop dups from being created (on 
 >> the
 >> contrary, but surely it's unusual for the live ranges to overlap).
 >> 
 >Are maxmin_Result the same variable?  Use -uid to find out.  If they
 >both have the same UID, they're the same and that's a bug.  There should
 >only be a single PHI node per variable in a basic block.
Why would that be a bug?  It just means that we have overlapping lifetimes
for the two objects. 

It's certainly a little odd, but I wouldn't go straight to classifying it
as a bug.  Instead I would suggest looking into the first place where these
two PHIs appeared and figure out why it happened.  It could be a bug or
it could be normal behavior.
jeff