optimization/5738: GCSE missed optimization

[rth@gcc.gnu.org]

Synopsis: GCSE missed optimization

State-Changed-From-To: open->closed
State-Changed-By: rth
State-Changed-When: Wed Apr  3 02:25:09 2002
State-Changed-Why:
    That's not how partial redundancy elimination (PRE) works.
    The object with PRE is to minimize the number of evaluations
    of an expression *along a path*.  There is already one
    evaluation along each path, thus PRE considers things
    optimal.
    
    You want global value numbering or something, which we 
    don't implement.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=5738