Reload generate invalid instruction on ppc64

[Carrot Wei <carrot at google dot com>]

Hi Vlad

When I use ppc64 gcc4.9 to compile an internal application I got an
ICE due to an invalid instruction generated by reload.

Before IRA, I have following insns:

(insn 139 136 581 10 (set (reg:DI 567)
        (const_int 0 [0])) ./strings/stringpiece.h:205 discrim 1 520
{*movdi_internal64}
     (expr_list:REG_EQUIV (const_int 0 [0])
        (nil)))

...

(insn 231 1062 237 24 (set (reg:V2DI 401 [ vect_cst_.7586 ])
        (vec_concat:V2DI (reg:DI 235 [ fprint$lo_ ])
            (reg:DI 567))) 1066 {vsx_concat_v2di}
     (expr_list:REG_DEAD (reg:DI 235 [ fprint$lo_ ])
        (expr_list:REG_EQUAL (vec_concat:V2DI (reg:DI 235 [ fprint$lo_ ])
                (const_int 0 [0]))
            (nil))))

IRA decides register r567 should be spilled into memory

       a48(r567,l0)  -- assign memory
    48:r567 l0   mem


Later reload pass reload constant 0 into hard floating point r42 directly

(insn 1086 1062 231 24 (set (reg:DI 42 10)
        (const_int 0 [0])) 520 {*movdi_internal64}
     (nil))

(insn 231 1086 237 24 (set (reg:V2DI 32 0 [orig:401 vect_cst_.7586 ] [401])
        (vec_concat:V2DI (reg:DI 32 0 [orig:235 fprint$lo_ ] [235])
            (reg:DI 42 10))) 1066 {vsx_concat_v2di}
     (expr_list:REG_EQUAL (vec_concat:V2DI (reg:DI 32 0 [orig:235
fprint$lo_ ] [235])
            (const_int 0 [0]))
        (nil)))

Unfortunately insn 1086 doesn't satisfy the constraints of insn
pattern movdi_internal64, so causing an ICE in later pass.


The reload insn 1086 is generated by following code in function
reload1.c:gen_reload

  /* If IN is a simple operand, use gen_move_insn.  */
  else if (OBJECT_P (in) || GET_CODE (in) == SUBREG)
    {
      tem = emit_insn (gen_move_insn (out, in));
      /* IN may contain a LABEL_REF, if so add a REG_LABEL_OPERAND note.  */
      mark_jump_label (in, tem, 0);
    }

After generating the move insn, reload doesn't check if the insn is
valid or if it can satisfy constraints. On ppc64 we can't load a
constant into fp/vsx register directly. Is it a bug here?

thanks a lot
Guozhi Wei