------- Comment #47 from lucier at math dot purdue dot edu 2009-02-13 17:22 ------- Subject: Re: [4.3/4.4 Regression] 30% performance slowdown in floating-point code caused by r118475
On Fri, 2009-02-13 at 16:32 +0000, bonzini at gnu dot org wrote: > > > ------- Comment #46 from bonzini at gnu dot org 2009-02-13 16:32 ------- > Regarding your comment in bug 26854: > > > address calculations are no longer optimized as much as they > > were before > > Sometimes, actually, they are optimized better. It depends on the case. Yes. I don't see why the optimizations in CSE, which were relatively cheap and which were effective for this case, needed to be disabled when FWPROP was added without, evidently, understanding why FWPROP does not do what CSE was already doing. > In comment #42, also, you talked about -O1, where fwprop is not enabled. So > I'm failing to understand if the problem is at the tree or RTL level for this > bug. When I add -fforward-propagate to the command line, then the assembly code changes in some ways, but the performance problem remains the same. Brad -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33928
