on an indirect reference may alias. */
static bool
-nonaliasing_component_refs_p (tree ref1, tree type1,
- HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
- tree ref2, tree type2,
- HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2)
+aliasing_component_refs_p (tree ref1, tree type1,
+ HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
+ tree ref2, tree type2,
+ HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2)
{
/* If one reference is a component references through pointers try to find a
common base and apply offset based disambiguation. This handles
offset1 -= offadj;
return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
}
- /* If we have two type access paths B1.path1 and B2.path2 they may
- only alias if either B1 is in B2.path2 or B2 is in B1.path1. */
- return false;
+
+ /* We haven't found any common base to apply offset-based disambiguation.
+ There are two cases:
+ 1. The base access types have the same alias set. This can happen
+ in Ada when a function with an unconstrained parameter passed by
+ reference is called on a constrained object and inlined: the types
+ have the same alias set but aren't equivalent. The references may
+ alias in this case.
+ 2. The base access types don't have the same alias set, i.e. one set
+ is a subset of the other. We have proved that B1 is not in the
+ access path B2.path and that B2 is not in the access path B1.path
+ so the references may not alias. */
+ return get_alias_set (type1) == get_alias_set (type2);
}
/* Return true if two memory references based on the variables BASE1
if (ref1 && ref2
&& handled_component_p (ref1)
&& handled_component_p (ref2))
- return nonaliasing_component_refs_p (ref1, TREE_TYPE (TREE_TYPE (ptr1)),
- offset1, max_size1,
- ref2, TREE_TYPE (base2),
- offset2, max_size2);
+ return aliasing_component_refs_p (ref1, TREE_TYPE (TREE_TYPE (ptr1)),
+ offset1, max_size1,
+ ref2, TREE_TYPE (base2),
+ offset2, max_size2);
return true;
}
if (ref1 && ref2
&& handled_component_p (ref1)
&& handled_component_p (ref2))
- return nonaliasing_component_refs_p (ref1, TREE_TYPE (TREE_TYPE (ptr1)),
- offset1, max_size1,
- ref2, TREE_TYPE (TREE_TYPE (ptr2)),
- offset2, max_size2);
+ return aliasing_component_refs_p (ref1, TREE_TYPE (TREE_TYPE (ptr1)),
+ offset1, max_size1,
+ ref2, TREE_TYPE (TREE_TYPE (ptr2)),
+ offset2, max_size2);
return true;
}