[Bug other/103926] New: "wQ" broken

[aik at ozlabs dot ru via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103926

            Bug ID: 103926
           Summary: "wQ" broken
           Product: gcc
           Version: 11.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: other
          Assignee: unassigned at gcc dot gnu.org
          Reporter: aik at ozlabs dot ru
                CC: segher at gcc dot gnu.org
  Target Milestone: ---
              Host: power8
            Target: powerpc64le-linux
             Build: 3b0ba97fafe8 (2 week old releases/gcc-11)

Using `wQ` constraint ("memory acceptable by `lq`") makes gcc crash. Note that
without "-O2" gcc gently fails (not sure why).

The issue recreates on gcc-11 from git and Ubuntu 2104's gcc (10.3.0-1ubuntu1).

[fstn1-p1 ~]$
/home/aik/pbuild/crossgcc/gcc-powerpc64le-linux-11.2.1-2.37.50-nolibc/bin/powerpc64le-linux-gcc
gccbug.c -o gccbug.o -O2
gccbug.c: In function ‘f’:
gccbug.c:6:1: error: unrecognizable insn:
    6 | }
      | ^
(insn 6 11 9 2 (parallel [
            (set (reg:TI 10 10 [orig:118 v ] [118])
                (asm_operands/v:TI ("lq %0, 0(%1)") ("=&r") 0 [
                        (mem/f/c:DI (reg:DI 9 9 [120]) [1 ptr+0 S8 A128])
                    ]
                     [
                        (asm_input:DI ("wQ") gccbug.c:5)
                    ]
                     [] gccbug.c:5))
            (clobber (reg:SI 98 ca))
        ]) "gccbug.c":5:2 -1
     (nil))
during RTL pass: postreload
gccbug.c:6:1: internal compiler error: in extract_constrain_insn, at
recog.c:2671
0x10190343 _fatal_insn(char const*, rtx_def const*, char const*, int, char
const*)
        /home/aik/p/gcc/gcc/gcc/rtl-error.c:108
0x10190397 _fatal_insn_not_found(rtx_def const*, char const*, int, char const*)
        /home/aik/p/gcc/gcc/gcc/rtl-error.c:116
0x1082fe6b extract_constrain_insn(rtx_insn*)
        /home/aik/p/gcc/gcc/gcc/recog.c:2671
0x107ea1bf reload_cse_simplify_operands
        /home/aik/p/gcc/gcc/gcc/postreload.c:407
0x107ebd5f reload_cse_simplify
        /home/aik/p/gcc/gcc/gcc/postreload.c:190
0x107ebd5f reload_cse_regs_1
        /home/aik/p/gcc/gcc/gcc/postreload.c:238
0x107edf7b reload_cse_regs
        /home/aik/p/gcc/gcc/gcc/postreload.c:66
0x107edf7b execute
        /home/aik/p/gcc/gcc/gcc/postreload.c:2359
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.

[fstn1-p1 ~]$ cat gccbug.c 
void f(void)
{
        void *ptr;
        __int128 v;
        asm volatile("lq %0, 0(%1)" : "=&r" (v) : "wQ" (ptr));
}