[3.4/mainline] PR target/15340

[Jan Hubicka <jh at suse dot cz>]

Hi,
In this testcase the sequence:

(insn 69 70 71 1 (set (reg/f:SI 92)
        (plus:SI (reg/f:SI 20 frame)
            (const_int -1 [0xffffffff]))) 137 {*lea_1} (nil)
    (nil))
...
(insn 37 36 40 2 (set (reg/v:SI 63 [ y ])
        (sign_extend:SI (mem/s:QI (mult:SI (reg/f:SI 92)
                    (const_int 2 [0x2])) [0 dir S1 A8]))) 86 {extendqisi2} (nil)
    (nil))

gets converted via rematiralization into:

(insn:HI 35 34 46 2 0x4017a39c (set (reg/v:SI 3 ebx [orig:65 y ] [65])
        (sign_extend:SI (mem/s:QI (mult:SI (plus:SI (reg/f:SI 6 ebp)
                        (const_int -13 [0xfffffff3]))
                    (const_int 2 [0x2])) [0 dir S1 A8]))) 93 {extendqisi2} (nil)
    (nil))

and reload does not notice the address being invalid.

Only way to fix this I can think of is to teach find_reload_addresses_1 about
the fact that MULT expr in addressing never contains nested non-trivial
expression  (is this valid for all targets not definining custom decomposition
of reload addresses?).  This is not completely satisfactory sollution but it is
best I was able to come with.

Regtested i686-pc-gnu-linux, full bootstrap/regtest in progress, OK assuming it passes?

int globl;

void dummy(char arg)
{
    globl = arg;
}

int main(int argc, char *argv[])
{
    char dir[1];
    int y = 0, best;

    while (y > *argv[0])
    {
        best = (int)dir;
        y = dir[best];
        dummy(*argv[1|best]);
    }
    return 0;
}
	PR target/15340
	* reload.c (find_reloads_address_1): Decompose complex MULT expressions.
*** ../../gcc.old/gcc/reload.c	Fri Jun 18 18:22:41 2004
--- reload.c	Thu Jun 24 17:33:25 2004
*************** find_reloads_address_1 (enum machine_mod
*** 5368,5374 ****
  				    type, ind_levels, insn);
  	  }
        }
! 
        return 0;
  
      case POST_MODIFY:
--- 5368,5392 ----
  				    type, ind_levels, insn);
  	  }
        }
!       return 0;
!     case MULT:
!       {
! 	rtx orig_op0 = XEXP (x, 0);
! 	rtx orig_op1 = XEXP (x, 1);
! 	RTX_CODE code0 = GET_CODE (orig_op0);
! 	RTX_CODE code1 = GET_CODE (orig_op1);
! 
! 	/* As a part of rematerialization process, we possibly inserted non-trivial
! 	   expression as left operand.  Expect MULT to be useable only on index
! 	   registers and reload.  */
! 	if (code0 == MULT || code0 == PLUS)
! 	  {
! 	    find_reloads_address_1 (mode, orig_op0, 1, &XEXP (x, 0), opnum,
! 				    type, ind_levels, insn);
! 	    find_reloads_address_1 (mode, orig_op1, 0, &XEXP (x, 1), opnum,
! 				    type, ind_levels, insn);
! 	  }
!       }
        return 0;
  
      case POST_MODIFY: