[Bug target/35135] unable to find a register to spill in class ‘GENERAL_REGS’ with global registers

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

------- Comment #6 from rguenth at gcc dot gnu dot org  2008-02-12 18:48 -------
The new testcase works for me with older releases (-O2 is enough), but 2.95.4
fails as well.  The difference from 4.2 to 4.3 is that 4.2 uses two induction
variables, while 4.3 uses one.  After lreg 4.2 has

(insn 21 19 22 3 (set (reg:DI 68)
        (mem:DI (plus:SI (plus:SI (reg:SI 64 [ ivtmp.44 ])
                    (reg/v/f:SI 67 [ ptr ]))
                (const_int 160 [0xa0])) [0 S8 A64])) 80 {*movdi_2} (nil)
    (expr_list:REG_EQUIV (mem:DI (plus:SI (plus:SI (reg:SI 64 [ ivtmp.44 ])
                    (reg/v/f:SI 67 [ ptr ]))
                (const_int 160 [0xa0])) [0 S8 A64])
        (nil)))

(insn 22 21 23 3 (set (mem/s/j:DI (reg/f:SI 63 [ ivtmp.51 ]) [0 <variable>._q+0
S8 A8])
        (reg:DI 68)) 80 {*movdi_2} (insn_list:REG_DEP_TRUE 21 (nil))
    (expr_list:REG_DEAD (reg:DI 68)
        (nil)))

(insn 23 22 24 3 (parallel [
            (set (reg:SI 64 [ ivtmp.44 ])
                (plus:SI (reg:SI 64 [ ivtmp.44 ])
                    (const_int 16 [0x10])))
            (clobber (reg:CC 17 flags))
        ]) 216 {*addsi_1} (nil)
    (expr_list:REG_UNUSED (reg:CC 17 flags)
        (nil)))

(insn 24 23 26 3 (parallel [
            (set (reg/f:SI 63 [ ivtmp.51 ])
                (plus:SI (reg/f:SI 63 [ ivtmp.51 ])
                    (const_int 16 [0x10])))
            (clobber (reg:CC 17 flags))
        ]) 216 {*addsi_1} (nil)
    (expr_list:REG_UNUSED (reg:CC 17 flags)
        (nil)))
...

while 4.3 ends up with

(insn 14 13 15 3 t.c:25 (set (reg:DI 67)
        (mem:DI (plus:SI (plus:SI (reg/v/f:SI 66 [ ptr ])
                    (reg:SI 63 [ ivtmp.15 ]))
                (const_int 160 [0xa0])) [0 S8 A64])) 88 {*movdi_2}
(expr_list:REG_EQUIV (mem:DI (plus:SI (plus:SI (reg/v/f:SI 66 [ ptr ])
                    (reg:SI 63 [ ivtmp.15 ]))
                (const_int 160 [0xa0])) [0 S8 A64])
        (nil)))

(insn 15 14 16 3 t.c:25 (set (mem/s/j:DI (plus:SI (reg/v/f:SI 65 [ env ])
                (reg:SI 63 [ ivtmp.15 ])) [0 <variable>._q+0 S8 A8])
        (reg:DI 67)) 88 {*movdi_2} (expr_list:REG_DEAD (reg:DI 67)
        (nil)))

(insn 16 15 18 3 t.c:25 (parallel [
            (set (reg:SI 63 [ ivtmp.15 ])
                (plus:SI (reg:SI 63 [ ivtmp.15 ])
                    (const_int 16 [0x10])))
            (clobber (reg:CC 17 flags))
        ]) 249 {*addsi_1} (expr_list:REG_UNUSED (reg:CC 17 flags)
        (nil)))

Or before expand for 4.2:

<bb 2>:
  ivtmp.51 = (unsigned int) &env->xmm_regs[0]._q[0];
  ivtmp.44 = 0;

<L0>:;
  MEM[index: ivtmp.51] = MEM[base: ptr, index: ivtmp.44, offset: 160];
  ivtmp.44 = ivtmp.44 + 16;
  ivtmp.51 = ivtmp.51 + 16;
  if (ivtmp.44 != 128) goto <L0>; else goto <L2>;

<L2>:;
  return;

while 4.3 starts with:

<bb 2>:
  ivtmp.15 = 0;

<bb 3>:
  MEM[base: env, index: ivtmp.15] = MEM[base: ptr, index: ivtmp.15, offset:
160];
  ivtmp.15 = ivtmp.15 + 16;
  if (ivtmp.15 != 128)
    goto <bb 3>;
  else
    goto <bb 4>;

<bb 4>:
  return;


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35135