- /* The base addresses of the read and write are different expressions.
- If they are both symbols and they are not accessed via AND, there is
- no conflict. We can bring knowledge of object alignment into play
- here. For example, on alpha, "char a, b;" can alias one another,
- though "char a; long b;" cannot. */
+ /* The base addresses are different expressions. If they are not accessed
+ via AND, there is no conflict. We can bring knowledge of object
+ alignment into play here. For example, on alpha, "char a, b;" can
+ alias one another, though "char a; long b;" cannot. AND addesses may
+ implicitly alias surrounding objects; i.e. unaligned access in DImode
+ via AND address can alias all surrounding object types except those
+ with aligment 8 or higher. */
+ if (GET_CODE (x) == AND && GET_CODE (y) == AND)
+ return 1;
+ if (GET_CODE (x) == AND
+ && (GET_CODE (XEXP (x, 1)) != CONST_INT
+ || (int) GET_MODE_UNIT_SIZE (y_mode) < -INTVAL (XEXP (x, 1))))
+ return 1;
+ if (GET_CODE (y) == AND
+ && (GET_CODE (XEXP (y, 1)) != CONST_INT
+ || (int) GET_MODE_UNIT_SIZE (x_mode) < -INTVAL (XEXP (y, 1))))
+ return 1;
+
+ /* Differing symbols not accessed via AND never alias. */