[Bug bootstrap/90781] New: ubsan bootstrap with -O3 -march=native fails at compare stage

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90781

            Bug ID: 90781
           Summary: ubsan bootstrap with -O3 -march=native fails at
                    compare stage
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: bootstrap
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dcb314 at hotmail dot com
  Target Milestone: ---

For recent gcc trunk, this configuration works fine on my machine:

../trunk/configure --prefix=/home/dcb/gcc/results.272000.ubsan \
        --with-build-config=bootstrap-ubsan \
        --disable-multilib \
        --disable-werror \
        --enable-checking=yes \
        --enable-languages=c,c++,fortran
sed 's/-O2/-O3/' < Makefile > Makefile.tmp
mv Makefile.tmp Makefile

but when I change the sed line to add flag -march=native:

sed 's/-O2/-O3 -march=native/' < Makefile > Makefile.tmp

then the bootstrap fails when comparing stages 2 and 3.

/proc/cpuinfo says

vendor_id       : AuthenticAMD
cpu family      : 21
model           : 2
model name      : AMD FX(tm)-8350 Eight-Core Processor

which, if I recall correctly, is bulldozer i.e. -fbdver2.