struct type_change_info
{
+ /* Offset into the object where there is the virtual method pointer we are
+ looking for. */
+ HOST_WIDE_INT offset;
+ /* The declaration or SSA_NAME pointer of the base that we are checking for
+ type change. */
+ tree object;
+ /* If we actually can tell the type that the object has changed to, it is
+ stored in this field. Otherwise it remains NULL_TREE. */
+ tree known_current_type;
/* Set to true if dynamic type change has been detected. */
bool type_maybe_changed;
+ /* Set to true if multiple types have been encountered. known_current_type
+ must be disregarded in that case. */
+ bool multiple_types_encountered;
};
/* Return true if STMT can modify a virtual method table pointer.
return true;
}
+/* If STMT can be proved to be an assignment to the virtual method table
+ pointer of ANALYZED_OBJ and the type associated with the new table
+ identified, return the type. Otherwise return NULL_TREE. */
+
+static tree
+extr_type_from_vtbl_ptr_store (gimple stmt, struct type_change_info *tci)
+{
+ HOST_WIDE_INT offset, size, max_size;
+ tree lhs, rhs, base;
+
+ if (!gimple_assign_single_p (stmt))
+ return NULL_TREE;
+
+ lhs = gimple_assign_lhs (stmt);
+ rhs = gimple_assign_rhs1 (stmt);
+ if (TREE_CODE (lhs) != COMPONENT_REF
+ || !DECL_VIRTUAL_P (TREE_OPERAND (lhs, 1))
+ || TREE_CODE (rhs) != ADDR_EXPR)
+ return NULL_TREE;
+ rhs = get_base_address (TREE_OPERAND (rhs, 0));
+ if (!rhs
+ || TREE_CODE (rhs) != VAR_DECL
+ || !DECL_VIRTUAL_P (rhs))
+ return NULL_TREE;
+
+ base = get_ref_base_and_extent (lhs, &offset, &size, &max_size);
+ if (offset != tci->offset
+ || size != POINTER_SIZE
+ || max_size != POINTER_SIZE)
+ return NULL_TREE;
+ if (TREE_CODE (base) == MEM_REF)
+ {
+ if (TREE_CODE (tci->object) != MEM_REF
+ || TREE_OPERAND (tci->object, 0) != TREE_OPERAND (base, 0)
+ || !tree_int_cst_equal (TREE_OPERAND (tci->object, 1),
+ TREE_OPERAND (base, 1)))
+ return NULL_TREE;
+ }
+ else if (tci->object != base)
+ return NULL_TREE;
+
+ return DECL_CONTEXT (rhs);
+}
+
/* Callback of walk_aliased_vdefs and a helper function for
detect_type_change to check whether a particular statement may modify
the virtual table pointer, and if possible also determine the new type of
if (stmt_may_be_vtbl_ptr_store (stmt))
{
+ tree type;
+ type = extr_type_from_vtbl_ptr_store (stmt, tci);
+ if (tci->type_maybe_changed
+ && type != tci->known_current_type)
+ tci->multiple_types_encountered = true;
+ tci->known_current_type = type;
tci->type_maybe_changed = true;
return true;
}
return false;
}
-/* Detect whether the dynamic type of ARG has changed (before callsite CALL) by
- looking for assignments to its virtual table pointer. If it is, return true
- and fill in the jump function JFUNC with relevant type information or set it
- to unknown. ARG is the object itself (not a pointer to it, unless
- dereferenced). BASE is the base of the memory access as returned by
- get_ref_base_and_extent, as is the offset. */
+
+
+/* Like detect_type_change but with extra argument COMP_TYPE which will become
+ the component type part of new JFUNC of dynamic type change is detected and
+ the new base type is identified. */
static bool
-detect_type_change (tree arg, tree base, gimple call,
- struct ipa_jump_func *jfunc, HOST_WIDE_INT offset)
+detect_type_change_1 (tree arg, tree base, tree comp_type, gimple call,
+ struct ipa_jump_func *jfunc, HOST_WIDE_INT offset)
{
struct type_change_info tci;
ao_ref ao;
if (!flag_devirtualize || !gimple_vuse (call))
return false;
- tci.type_maybe_changed = false;
-
ao.ref = arg;
ao.base = base;
ao.offset = offset;
ao.ref_alias_set = -1;
ao.base_alias_set = -1;
+ tci.offset = offset;
+ tci.object = get_base_address (arg);
+ tci.known_current_type = NULL_TREE;
+ tci.type_maybe_changed = false;
+ tci.multiple_types_encountered = false;
+
walk_aliased_vdefs (&ao, gimple_vuse (call), check_stmt_for_type_change,
&tci, NULL);
if (!tci.type_maybe_changed)
return false;
- jfunc->type = IPA_JF_UNKNOWN;
+ if (!tci.known_current_type
+ || tci.multiple_types_encountered
+ || offset != 0)
+ jfunc->type = IPA_JF_UNKNOWN;
+ else
+ {
+ jfunc->type = IPA_JF_KNOWN_TYPE;
+ jfunc->value.known_type.base_type = tci.known_current_type;
+ jfunc->value.known_type.component_type = comp_type;
+ }
+
return true;
}
+/* Detect whether the dynamic type of ARG has changed (before callsite CALL) by
+ looking for assignments to its virtual table pointer. If it is, return true
+ and fill in the jump function JFUNC with relevant type information or set it
+ to unknown. ARG is the object itself (not a pointer to it, unless
+ dereferenced). BASE is the base of the memory access as returned by
+ get_ref_base_and_extent, as is the offset. */
+
+static bool
+detect_type_change (tree arg, tree base, gimple call,
+ struct ipa_jump_func *jfunc, HOST_WIDE_INT offset)
+{
+ return detect_type_change_1 (arg, base, TREE_TYPE (arg), call, jfunc, offset);
+}
+
/* Like detect_type_change but ARG is supposed to be a non-dereferenced pointer
SSA name (its dereference will become the base and the offset is assumed to
be zero). */
static bool
detect_type_change_ssa (tree arg, gimple call, struct ipa_jump_func *jfunc)
{
+ tree comp_type;
+
gcc_checking_assert (TREE_CODE (arg) == SSA_NAME);
if (!flag_devirtualize
|| !POINTER_TYPE_P (TREE_TYPE (arg))
|| TREE_CODE (TREE_TYPE (TREE_TYPE (arg))) != RECORD_TYPE)
return false;
+ comp_type = TREE_TYPE (TREE_TYPE (arg));
arg = build2 (MEM_REF, ptr_type_node, arg,
- build_int_cst (ptr_type_node, 0));
+ build_int_cst (ptr_type_node, 0));
- return detect_type_change (arg, arg, call, jfunc, 0);
+ return detect_type_change_1 (arg, arg, comp_type, call, jfunc, 0);
}
/* Callback of walk_aliased_vdefs. Flags that it has been invoked to the
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