https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86487
--- Comment #10 from avieira at gcc dot gnu.org --- Hi Vlad, I don't think it is a duplication. I believe this PR is caused by an issue with 'uses_hard_regs_p' and paradoxical subregs. I proposed a patch in https://gcc.gnu.org/ml/gcc-patches/2019-01/msg00307.html , though it has a mistake, I forgot to add '|| SUBREG_P (x)' to the 'if (REG_P (x))' line since x can now be a subreg. I haven't had much time lately, but I am now running the last bootstrap, have done arm and aarch64, now doing x86. I can't reproduce this on GCC 9 but I can on 8 and earlier and the latent bug is still there on 9. So I believe we should fix it regardless. Once the bootstrap is done Ill post the fixed patch + testcase (really only useful for gcc-8) on the mailing list. Cheers, Andre