------- Comment #11 from amylaar at gcc dot gnu dot org 2009-01-14 22:06 ------- (In reply to comment #10) > You would completely underestimate the optimization opportunities PRE > unleashes.
Well, at least for partial-partial-RE, as mentioned before in PR38401, benchmarks indicate that we'd be better without it altogether than what it is in its current form. If we could use a cost calculation to avoid the code pessimization while keeping some of the potential penefit of partial-partial-RE, that should be even better. The potentially harmful impact of ordinary PRE is lesser because if you put in a constant load where the expression is at least fully anticipatable, you swap a constant load for some other operation, worst case that means an expensive constant load and two branches instead of a simple icond-exec operation - that's bad, but not nearly as bad as blowing up always-executed path along with everything else exponentially. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38785
