On Sat, 11 Mar 2023, Jeff Law wrote: > > > On 3/7/23 04:08, Richard Biener via Gcc-patches wrote: > > The following addresses PR109046 by adding an optimization to forwprop > > to combine a piecewise complex load to a complex load when there are > > no uses of the components. That's something useful in general and > > easier to do than avoiding the splitting in complex lowering. > Presumably instead of "no uses of the components" you meant to say "no other > uses of the components".
Yes, will reword. > > > > The testcase exercises both the manual and the complex lowering case. > > > > Bootstrapped and tested on x86_64-unknown-linux-gnu, OK? > > > > Thanks, > > Richard. > > > > PR tree-optimization/109046 > > * tree-ssa-forwprop.cc (pass_forwprop::execute): Combine > > piecewise complex loads. > > > > * gcc.dg/tree-ssa/forwprop-39.c: New testcase. > > --- > > [ ... ] > > + /* Rewrite a component-wise load of a complex to a complex > > + load if the components are not used separately. */ > > + else if (TREE_CODE (rhs) == SSA_NAME > > + && has_single_use (rhs) > Did you really meant to test that RHS is single use? Isn't that the > COMPLEX_EXPR here? It would seem fine to me to allow multiple uses of the > COMPLEX_EXPR itself. Am I missing something? Yeah, rhs is actually rhs1, the first operand of the COMPLEX_EXPR ... > The only conceptual concern I have would be volatile objects. But in that > case were're replacing a piecewise load of the volatile with a single complex > load. That probably better matches what the developer expected anyway. Ah, but good that you notice - we shouldn't do this combination for volatile component loads. I'll adjust accordingly re-test and commit. > So OK as-is if you really wanted the COMPLEX_EXPR to have a single use. Or OK > after removing that test. Thanks, Richard.
