The latest GCC 10/11/12 branches do not build the powerpc-rtems target due to a build error in the -mcpu=8540 multilib:

/tmp/sh/b-gcc-powerpc-rtems6/./gcc/xgcc -B/tmp/sh/b-gcc-powerpc-rtems6/./gcc/ -nostdinc -B/tmp/sh/b-gcc-powerpc-rtems6/powerpc-rtems6/m8540/nof/newlib/ -isystem /tmp/sh/b-gcc-powerpc-rtems6/powerpc-rtems6/m8540/nof/newlib/targ-include -isystem /home/EB/sebastian_h/src/gcc/newlib/libc/include -B/tmp/sh/i-powerpc-rtems6/powerpc-rtems6/bin/ -B/tmp/sh/i-powerpc-rtems6/powerpc-rtems6/lib/ -isystem /tmp/sh/i-powerpc-rtems6/powerpc-rtems6/include -isystem /tmp/sh/i-powerpc-rtems6/powerpc-rtems6/sys-include  -mcpu=8540 -msoft-float -g -O2 -O2 -I/home/EB/sebastian_h/src/gcc/libgcc/../newlib/libc/sys/rtems/include -g -O2 -DIN_GCC  -DCROSS_DIRECTORY_STRUCTURE  -W -Wall -Wno-narrowing -Wwrite-strings -Wcast-qual -Wstrict-prototypes -Wmissing-prototypes -Wold-style-definition  -isystem ./include   -g -DIN_LIBGCC2 -fbuilding-libgcc -fno-stack-protector -Dinhibit_libc  -I. -I. -I../../../.././gcc -I/home/EB/sebastian_h/src/gcc/libgcc -I/home/EB/sebastian_h/src/gcc/libgcc/. -I/home/EB/sebastian_h/src/gcc/libgcc/../gcc -I/home/EB/sebastian_h/src/gcc/libgcc/../include  -DHAVE_CC_TLS  -o _negvdi2.o -MT _negvdi2.o -MD -MP -MF _negvdi2.dep -DL_negvdi2 -c /home/EB/sebastian_h/src/gcc/libgcc/libgcc2.c -fvisibility=hidden -DHIDE_EXPORTS
/tmp/ccZJ18fW.s: Assembler messages:
/tmp/ccZJ18fW.s:24: Error: unrecognized opcode: `isel'
make: *** [Makefile:501: _negvdi2.o] Error 1

The assembler is called like this:

/tmp/sh/b-gcc-powerpc-rtems6/./gcc/as -I /home/EB/sebastian_h/src/gcc/libgcc/../newlib/libc/sys/rtems/include -I . -I . -I ../../../.././gcc -I /home/EB/sebastian_h/src/gcc/libgcc -I /home/EB/sebastian_h/src/gcc/libgcc/. -I /home/EB/sebastian_h/src/gcc/libgcc/../gcc -I /home/EB/sebastian_h/src/gcc/libgcc/../include -a32 -me500 -mbig -o _negvdi2.o _negvdi2.s

Using -me500 seems to be all right, however, the file contains a machine directive:

    .file    "libgcc2.c"
    .machine ppc
    .section    ".text"

If I remove the ".machine ppc" by hand, the file can be assembled with the above command line.

The affect of the patch for PR100108 is:

diff -u _negvdi2.s.before _negvdi2.s.after
--- _negvdi2.s.before   2022-01-11 09:07:43.313828636 +0100
+++ _negvdi2.s.after    2022-01-11 08:54:08.424946502 +0100
@@ -1,5 +1,5 @@
        .file   "libgcc2.c"
-       .machine power9
+       .machine ppc
        .section        ".text"
 .Ltext0:
        .align 2