+/* Simplify a MEM based on its attributes. This is the default
+ delegitimize_address target hook, and it's recommended that every
+ overrider call it. */
+
+rtx
+delegitimize_mem_from_attrs (rtx x)
+{
+ /* MEMs without MEM_OFFSETs may have been offset, so we can't just
+ use their base addresses as equivalent. */
+ if (MEM_P (x)
+ && MEM_EXPR (x)
+ && MEM_OFFSET (x))
+ {
+ tree decl = MEM_EXPR (x);
+ enum machine_mode mode = GET_MODE (x);
+ HOST_WIDE_INT offset = 0;
+
+ switch (TREE_CODE (decl))
+ {
+ default:
+ decl = NULL;
+ break;
+
+ case VAR_DECL:
+ break;
+
+ case ARRAY_REF:
+ case ARRAY_RANGE_REF:
+ case COMPONENT_REF:
+ case BIT_FIELD_REF:
+ case REALPART_EXPR:
+ case IMAGPART_EXPR:
+ case VIEW_CONVERT_EXPR:
+ {
+ HOST_WIDE_INT bitsize, bitpos;
+ tree toffset;
+ int unsignedp = 0, volatilep = 0;
+
+ decl = get_inner_reference (decl, &bitsize, &bitpos, &toffset,
+ &mode, &unsignedp, &volatilep, false);
+ if (bitsize != GET_MODE_BITSIZE (mode)
+ || (bitpos % BITS_PER_UNIT)
+ || (toffset && !host_integerp (toffset, 0)))
+ decl = NULL;
+ else
+ {
+ offset += bitpos / BITS_PER_UNIT;
+ if (toffset)
+ offset += TREE_INT_CST_LOW (toffset);
+ }
+ break;
+ }
+ }
+
+ if (decl
+ && mode == GET_MODE (x)
+ && TREE_CODE (decl) == VAR_DECL
+ && (TREE_STATIC (decl)
+ || DECL_THREAD_LOCAL_P (decl))
+ && DECL_RTL_SET_P (decl)
+ && MEM_P (DECL_RTL (decl)))
+ {
+ rtx newx;
+
+ offset += INTVAL (MEM_OFFSET (x));
+
+ newx = DECL_RTL (decl);
+
+ if (MEM_P (newx))
+ {
+ rtx n = XEXP (newx, 0), o = XEXP (x, 0);
+
+ /* Avoid creating a new MEM needlessly if we already had
+ the same address. We do if there's no OFFSET and the
+ old address X is identical to NEWX, or if X is of the
+ form (plus NEWX OFFSET), or the NEWX is of the form
+ (plus Y (const_int Z)) and X is that with the offset
+ added: (plus Y (const_int Z+OFFSET)). */
+ if (!((offset == 0
+ || (GET_CODE (o) == PLUS
+ && GET_CODE (XEXP (o, 1)) == CONST_INT
+ && (offset == INTVAL (XEXP (o, 1))
+ || (GET_CODE (n) == PLUS
+ && GET_CODE (XEXP (n, 1)) == CONST_INT
+ && (INTVAL (XEXP (n, 1)) + offset
+ == INTVAL (XEXP (o, 1)))
+ && (n = XEXP (n, 0))))
+ && (o = XEXP (o, 0))))
+ && rtx_equal_p (o, n)))
+ x = adjust_address_nv (newx, mode, offset);
+ }
+ else if (GET_MODE (x) == GET_MODE (newx)
+ && offset == 0)
+ x = newx;
+ }
+ }
+
+ return x;
+}
+\f