On Fri, Nov 8, 2013 at 4:18 PM, Joern Rennecke wrote: > On 8 November 2013 14:45, Steven Bosscher wrote: >> This is IMHO not OK without at least an explanation of why the >> comparison of two const_ints is not folded. Better yet would be to fix >> that underlying problem. We should not present such non-sense to the >> RTL parts of the middle end. > > Which part would be responsible to folding the comparison at -O1 ? > FWIW, as I just commented in the PR, one of the operands is an ssa_name > with a known value.
This usually is taken care of by one of the many propagation passes (CCP, VRP, forwprop, DOM, even FRE/PRE). The only cases I've previously encountered, where a known value ends up not being propagated, is when the propagation is somehow overlooked and the known value is only replaced at out-of-ssa time, i.e. TER. The only way to find out where the propagation should have happened, is by looking at the gimple dumps. Ciao! Steven
