[tree-ssa] tree-mustalias fix

[Jan Hubicka]

Hi,
followint testsuite testcase:
f (unsigned short Z[48])
{
  int j;
  unsigned short t1, t2, t3, T[48];
  unsigned short *p = T + 48;

  for (j = 1; j < 8; j++)
    {
      t1 = *Z++;
      *--p = *Z++;
      *--p = t1;
      t1 = inv(*Z++);
      t2 = -*Z++;
      t3 = -*Z++;
      *--p = inv(*Z++);
      *--p = t2;
      *--p = t3;
      *--p = t1;
    }
}
Produce following SSA representation at mustalias:
;; Function f (f)

f (Z)
{
  short unsigned int * p;
  short unsigned int T[48];
  short unsigned int t3;
  short unsigned int t2;
  short unsigned int t1;
  int j;
  short unsigned int T.7;
  int T.6;
  short int T.5;
  short int T.4;
  int T.3;
  int T.2;
  short unsigned int T.1;

<bb 0>:
  goto <bb 2> (<L1>);

<L0>:;
  t1_19 = *Z_5;
  Z_20 = Z_5 + 2B;
  p_21 = p_1 - 2B;
  T.1_22 = *Z_20;
  *p_21 = T.1_22;
  Z_24 = Z_5 + 4B;
  p_25 = p_1 - 4B;
  *p_25 = t1_19;
  T.1_27 = *Z_24;
  T.2_28 = (int)T.1_27;
  T.3_29 = inv (T.2_28);
  t1_31 = (short unsigned int)T.3_29;
  Z_32 = Z_5 + 6B;
  T.1_33 = *Z_32;
  T.4_34 = (short int)T.1_33;
  T.5_35 = -T.4_34;
  t2_36 = (short unsigned int)T.5_35;
  Z_37 = Z_5 + 8B;
  T.1_38 = *Z_37;
  T.4_39 = (short int)T.1_38;
  T.5_40 = -T.4_39;
  t3_41 = (short unsigned int)T.5_40;
  Z_42 = Z_5 + 10B;
  p_43 = p_1 - 6B;
  T.1_44 = *Z_42;
  T.2_45 = (int)T.1_44;
  T.6_46 = inv (T.2_45);
  T.7_48 = (short unsigned int)T.6_46;
  *p_43 = T.7_48;
  Z_50 = Z_5 + 12B;
  p_51 = p_1 - 8B;
  *p_51 = t2_36;
  p_53 = p_1 - 10B;
  *p_53 = t3_41;
  p_55 = p_1 - 12B;
  *p_55 = t1_31;
  j_57 = j_3 + 1;

  # Z_5 = PHI <Z_16(0), Z_50(1)>;
  # j_3 = PHI <1(0), j_57(1)>;
  # p_1 = PHI <&T + 96B(0), p_55(1)>;
<L1>:;
  if (j_3 <= 7) goto <L0>; else goto <L2>;

<L2>:;
<L3>:;
  return;

}

Notice definition of p_1.  We miss the fact that address of T is taken.  Fixed
by attached patch (that is simplification of earlier patch solving the same
problem).  At the very moment we don't get any problems as we don't promote
arrays, however I am just testing patch to do this.

Bootstrapped/regtested i686-pc-gnu-linux.  OK?

Honza

2003-12-19  Jan Hubicka  <jh@suse.cz>
	* tree-must-alias.c (find_addressable_vars): Deal properly with
	nontrivial memory addresses.
===================================================================
RCS file: /cvs/gcc/gcc/gcc/Attic/tree-must-alias.c,v
retrieving revision 1.1.2.16
diff -c -3 -p -r1.1.2.16 tree-must-alias.c
*** tree-must-alias.c	17 Dec 2003 03:36:14 -0000	1.1.2.16
--- tree-must-alias.c	19 Dec 2003 16:57:13 -0000
*************** find_addressable_vars (void)
*** 188,199 ****
  	    {
  	      tree t = PHI_ARG_DEF (phi, i);
  
  	      if (TREE_CODE (t) != ADDR_EXPR)
  		continue;
! 	      t = TREE_OPERAND (t, 0);
! 	      if (TREE_CODE (t) != VAR_DECL && TREE_CODE (t) != PARM_DECL)
! 		continue;
! 	      SET_BIT (addresses_needed, var_ann (t)->uid);
  	    }
  	}
      }
--- 188,200 ----
  	    {
  	      tree t = PHI_ARG_DEF (phi, i);
  
+ 	      if (TREE_CODE (t) == PLUS_EXPR)
+ 		t = TREE_OPERAND (t, 0);
  	      if (TREE_CODE (t) != ADDR_EXPR)
  		continue;
! 	      t = get_base_symbol (TREE_OPERAND (t, 0));
! 	      if (t && (TREE_CODE (t) == VAR_DECL || TREE_CODE (t) == PARM_DECL))
! 	        SET_BIT (addresses_needed, var_ann (t)->uid);
  	    }
  	}
      }