https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100782
--- Comment #4 from Sergei Trofimovich <slyfox at gcc dot gnu.org> ---
Bisected down to r11-4577
commit 44fbc9c6e02ca5b8f98f25b514ed7588e7ba733d
Author: Vladimir N. Makarov <vmaka...@redhat.com>
Date: Fri Oct 30 15:05:22 2020 -0400
Take insn scratch RA requirements into account in IRA.
The patch changes insn scratches which require registers for all
insn alternatives (in other words w/o X constraint in scratch
constraint string). This is done before IRA staring its work. LRA
still continue to change the rest scratches (with X constraint and in
insn created during IRA) into pseudos. As before the patch at the end
of LRA work, spilled scratch pseudos (for which X constraint was
chosen) changed into scratches back.
