On Wed, 2020-01-22 at 12:11 +0000, Richard Sandiford wrote: > In this PR, auto-inc-dec was trying to turn: > > (set (reg X) (plus (reg X) (const_int N))) > (clobber (mem (reg X))) > > into: > > (clobber (mem (pre_modify (reg X) ...))) > > But bare clobber insns are just there to describe dataflow. They're > not supposed to generate any code. > > This is part 2 of the fix for PR93124. The reason we have the > clobber above is that cprop replaced (reg sp) with (reg X) in: > > (clobber (mem (reg sp))) > > Part 1 stops that from happening, but I still think we should > prevent auto-inc-dec from "optimising" bare USEs and CLOBBERs > as a belt-and-braces fix. > > Tested on aarch64-linux-gnu and x86_64-linux-gnu. OK to install? > > Richard > > > 2020-01-22 Richard Sandiford <richard.sandif...@arm.com> > > gcc/ > PR rtl-optimization/93124 > * auto-inc-dec.c (merge_in_block): Don't add auto inc/decs to > bare USE and CLOBBER insns. > > gcc/testsuite/ > * gcc.dg/torture/pr93124.c: New test. OK.
Jeff >
