Created attachment 1815931 [details]
preprocessed source

Description of problem:
Modulus operation with input and output being a hard register will cause a internal compiler error when building with -O and -mcpu=power9 or power10.
There is already an upstream gcc12/git bug filed here: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101882

We found out that this bug is also reproducing in our gcc (gcc-11.2.1-2.2.el9.ppc64le).

Version-Release number of selected component (if applicable):
gcc-11.2.1-2.2.el9.ppc64le

How reproducible:
100%

Steps to Reproduce:

foofoo9.c:
  register a __asm__("r20");
  b() { a = a % 9 ; }
# does not occur with -O0, or with -mcpu=power8.
$ gcc  -O -mcpu=power9 foofoo9.c 

Actual results:
foo.c: In function ‘b’:
foo.c:2:23: error: unable to generate reloads for impossible constraints:
    2 |     b() { a = a % 9 ; }
      |                       ^
(insn 8 7 11 2 (set (reg/v:SI 20 20 [ a ])
        (mod:SI (reg/v:SI 20 20 [ a ])
            (reg:SI 121))) "foo.c":2:17 194 {*modsi3}
     (expr_list:REG_DEAD (reg:SI 121)
        (nil)))
during RTL pass: reload
foo.c:2:23: internal compiler error: in process_alt_operands, at lra-constraints.c:3108
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://bugzilla.redhat.com/bugzilla> for instructions.
Preprocessed source stored into /tmp/ccZWfCCO.out file, please attach this to your bugreport.


Expected results:
No internal compiler error.