[Bug target/71656] New: ICE in reload when generating code for -mcpu=power9 -mpower9-dform-vector

["bergner at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71656

            Bug ID: 71656
           Summary: ICE in reload when generating code for -mcpu=power9
                    -mpower9-dform-vector
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: bergner at gcc dot gnu.org
  Target Milestone: ---

The following test case ICEs when generating code for POWER9 vector dform
addressing and reload.  It compiles fine when using LRA:

bergner@genoa:~/gcc/BUGS/RELOAD$ cat bug.i 
typedef __attribute__((altivec(vector__))) int type_t;
type_t
fn1 (type_t *src)
{
  asm volatile ("# force the base reg on the load below to be spilled"
                   : /* no outputs */
                   : /* no inputs */
                   : "r0", "r1", "r3", "r4", "r5", "r6", "r7",
                     "r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15",
                     "r16", "r17", "r18", "r19", "r20", "r21", "r22", "r23",
                     "r24", "r25", "r26", "r27", "r28", "r29", "r30", "r31");
  return src[1];
}

bergner@genoa:~/gcc/BUGS/RELOAD$
/home/bergner/gcc/build/gcc-fsf-mainline-vec-dform-base/gcc/xgcc
-B/home/bergner/gcc/build/gcc-fsf-mainline-vec-dform-base/gcc -S -O1
-mcpu=power9 -mpower9-dform-vector -mno-lra bug.i 
bug.i:1:0: warning: -mpower9-dform-vector might need -mlra
 typedef __attribute__((altivec(vector__))) int type_t;

bug.i: In function âfn1â:
bug.i:13:1: error: insn does not satisfy its constraints:
 }
 ^
(insn 12 7 13 2 (set (reg/i:V4SI 79 2)
        (mem:V4SI (plus:DI (mem/c:DI (plus:DI (reg/f:DI 113 sfp)
                        (const_int 32 [0x20])) [2 %sfp+32 S8 A64])
                (const_int 16 [0x10])) [1 MEM[(type_t *)src_2(D) + 16B]+0 S16
A128])) bug.i:13 946 {*vsx_movv4si_64bit}
     (nil))
bug.i:13:1: internal compiler error: in extract_constrain_insn, at recog.c:2211

The problem is that rs6000_legitimize_reload_address() does not have any
support for POWER9 vector dform addresses.