On Wed, Sep 11, 2024 at 10:26 AM Eric Botcazou <botca...@adacore.com> wrote: > > Hi, > > the attached Ada testcase compiled with -O -flto exhibits a wrong code issue > when the 3 optimizations NRV + RSO + inlining are applied to the same call: if > the LHS of the call is marked write-only before inlining, then it will keep > the mark after inlining although it may be read in GIMPLE from that point on. > > The proposed fix is to always clear the flag during inlining in the RSO case. > Tested on x86-64/Linux, OK for the mainline?
Hmm, it looks to me that the IPA analysis marking the variable readonly in the first place is wrong - or that NRV may not be applied to such a variable later. Is NRV ever applied to say static const S s = ...; s = foo (); thus a readonly declared LHS? I think adjusting the varpool flag just during inline materialization doesn't resolve issues that appear when the wrong flag caused other wrong IPA decisions for example. Richard. > > 2024-09-11 Eric Botcazou <ebotca...@adacore.com> > > * tree-inline.cc (declare_return_variable): Clear writeonly flag on > a global variable used directly as the return slot. > > 2024-09-11 Eric Botcazou <ebotca...@adacore.com> > > * gnat.dg/lto27.adb: New test. > * gnat.dg/lto27_pkg1.ads, gnat.dg/lto27_pkg2.ads, > gnat.dg/lto27_pkg2.adb, gnat.dg/lto27_pkg3.ads: New helper. > > > -- > Eric Botcazou
