[Bug target/27538] execute/20030128-1.c FAILs

[kazu at gcc dot gnu dot org]

------- Comment #1 from kazu at gcc dot gnu dot org  2006-05-11 18:44 -------
Just for a reference, here is execute/20030128-1.c.

unsigned char x = 50;
volatile short y = -5;

int main ()
{
  x /= y;
  if (x != (unsigned char) -10)
    abort ();
  exit (0);
}

Now, with -O1, the load of y completely disappears.
Here is the dump of 20030128-1.c.160r.shorten up to a call to
a division subroutine.

(insn/f 55 8 56 (parallel [
            (set (mem/c:BLK (pre_dec:BLK (reg/f:SI 13 sp)) [0 A8])
                (unspec:BLK [
                        (reg:SI 4 r4)
                    ] 2))
            (use (reg:SI 14 lr))
        ]) 302 {*push_multi} (nil)
    (expr_list:REG_DEAD (reg:SI 14 lr)
        (expr_list:REG_DEAD (reg:SI 4 r4)
            (expr_list:REG_FRAME_RELATED_EXPR (sequence [
                        (set/f (reg/f:SI 13 sp)
                            (plus:SI (reg/f:SI 13 sp)
                                (const_int -8 [0xfffffffffffffff8])))
                        (set/f (mem/c:SI (reg/f:SI 13 sp) [0 S4 A32])
                            (reg:SI 4 r4))
                        (set/f (mem/c:SI (plus:SI (reg/f:SI 13 sp)
                                    (const_int 4 [0x4])) [0 S4 A32])
                            (reg:SI 14 lr))
                    ])
                (nil)))))

(note 56 55 10 NOTE_INSN_PROLOGUE_END)

(note 10 56 11 NOTE_INSN_DELETED)

(note 11 10 13 NOTE_INSN_DELETED)

(note 13 11 14 NOTE_INSN_DELETED)

(note 14 13 15 NOTE_INSN_DELETED)

(insn 15 14 16 (set (reg/f:SI 4 r4 [108])
        (mem:SI (label_ref 59) [0 S4 A32])) 145 {*arm_movsi_insn} (nil)
    (expr_list:REG_EQUIV (symbol_ref:SI ("x") [flags 0x2] <var_decl 0xf7f71d80
x>)
        (nil)))

(note 16 15 17 NOTE_INSN_DELETED)

(note 17 16 18 NOTE_INSN_DELETED)

(note 18 17 19 NOTE_INSN_DELETED)

(insn 19 18 20 (set (reg:SI 0 r0 [ x ])
        (zero_extend:SI (mem/c/i:QI (reg/f:SI 4 r4 [108]) [0 x+0 S1 A8]))) 128
{*arm_zero_extendqis\i2} (insn_list:REG_DEP_TRUE 15 (nil))
    (nil))

(insn 20 19 21 (set (reg:SI 1 r1)
        (const_int 0 [0x0])) 145 {*arm_movsi_insn} (nil)
    (nil))

(call_insn/u 21 20 23 (parallel [
            (set (reg:SI 0 r0)
                (call (mem:SI (symbol_ref:SI ("__aeabi_idiv") [flags 0x41]) [0
S4 A32])
                    (const_int 0 [0x0])))
            (use (const_int 0 [0x0]))
            (clobber (reg:SI 14 lr))
        ]) 230 {*call_value_symbol} (insn_list:REG_DEP_TRUE 19
(insn_list:REG_DEP_TRUE 20 (nil)))
    (expr_list:REG_DEAD (reg:SI 1 r1)
        (expr_list:REG_UNUSED (reg:SI 14 lr)
            (expr_list:REG_EH_REGION (const_int -1 [0xffffffffffffffff])
                (nil))))
    (expr_list:REG_DEP_TRUE (use (reg:SI 1 r1))
        (expr_list:REG_DEP_TRUE (use (reg:SI 0 r0 [ x ]))
            (nil))))


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27538