}
}
+/* Structure to be passed in between detect_type_change and
+ check_stmt_for_type_change. */
+
+struct type_change_info
+{
+ /* Set to true if dynamic type change has been detected. */
+ bool type_maybe_changed;
+};
+
+/* Return true if STMT can modify a virtual method table pointer.
+
+ This function makes special assumptions about both constructors and
+ destructors which are all the functions that are allowed to alter the VMT
+ pointers. It assumes that destructors begin with assignment into all VMT
+ pointers and that constructors essentially look in the following way:
+
+ 1) The very first thing they do is that they call constructors of ancestor
+ sub-objects that have them.
+
+ 2) Then VMT pointers of this and all its ancestors is set to new values
+ corresponding to the type corresponding to the constructor.
+
+ 3) Only afterwards, other stuff such as constructor of member sub-objects
+ and the code written by the user is run. Only this may include calling
+ virtual functions, directly or indirectly.
+
+ There is no way to call a constructor of an ancestor sub-object in any
+ other way.
+
+ This means that we do not have to care whether constructors get the correct
+ type information because they will always change it (in fact, if we define
+ the type to be given by the VMT pointer, it is undefined).
+
+ The most important fact to derive from the above is that if, for some
+ statement in the section 3, we try to detect whether the dynamic type has
+ changed, we can safely ignore all calls as we examine the function body
+ backwards until we reach statements in section 2 because these calls cannot
+ be ancestor constructors or destructors (if the input is not bogus) and so
+ do not change the dynamic type (this holds true only for automatically
+ allocated objects but at the moment we devirtualize only these). We then
+ must detect that statements in section 2 change the dynamic type and can try
+ to derive the new type. That is enough and we can stop, we will never see
+ the calls into constructors of sub-objects in this code. Therefore we can
+ safely ignore all call statements that we traverse.
+ */
+
+static bool
+stmt_may_be_vtbl_ptr_store (gimple stmt)
+{
+ if (is_gimple_call (stmt))
+ return false;
+ else if (is_gimple_assign (stmt))
+ {
+ tree lhs = gimple_assign_lhs (stmt);
+
+ if (TREE_CODE (lhs) == COMPONENT_REF
+ && !DECL_VIRTUAL_P (TREE_OPERAND (lhs, 1))
+ && !AGGREGATE_TYPE_P (TREE_TYPE (lhs)))
+ return false;
+ /* In the future we might want to use get_base_ref_and_offset to find
+ if there is a field corresponding to the offset and if so, proceed
+ almost like if it was a component ref. */
+ }
+ return true;
+}
+
+/* Callbeck 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
+ the (sub-)object. It stores its result into DATA, which points to a
+ type_change_info structure. */
+
+static bool
+check_stmt_for_type_change (ao_ref *ao ATTRIBUTE_UNUSED, tree vdef, void *data)
+{
+ gimple stmt = SSA_NAME_DEF_STMT (vdef);
+ struct type_change_info *tci = (struct type_change_info *) data;
+
+ if (stmt_may_be_vtbl_ptr_store (stmt))
+ {
+ tci->type_maybe_changed = true;
+ return true;
+ }
+ else
+ 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. */
+
+static bool
+detect_type_change (tree arg, tree base, gimple call,
+ struct ipa_jump_func *jfunc, HOST_WIDE_INT offset)
+{
+ struct type_change_info tci;
+ ao_ref ao;
+
+ gcc_checking_assert (DECL_P (arg)
+ || TREE_CODE (arg) == MEM_REF
+ || handled_component_p (arg));
+ /* Const calls cannot call virtual methods through VMT and so type changes do
+ not matter. */
+ if (!gimple_vuse (call))
+ return false;
+
+ tci.type_maybe_changed = false;
+
+ ao.ref = arg;
+ ao.base = base;
+ ao.offset = offset;
+ ao.size = POINTER_SIZE;
+ ao.max_size = ao.size;
+ ao.ref_alias_set = -1;
+ ao.base_alias_set = -1;
+
+ 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;
+ return true;
+}
+
+/* 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)
+{
+ gcc_checking_assert (TREE_CODE (arg) == SSA_NAME);
+ if (!POINTER_TYPE_P (TREE_TYPE (arg))
+ || TREE_CODE (TREE_TYPE (TREE_TYPE (arg))) != RECORD_TYPE)
+ return false;
+
+ arg = build2 (MEM_REF, ptr_type_node, arg,
+ build_int_cst (ptr_type_node, 0));
+
+ return detect_type_change (arg, arg, call, jfunc, 0);
+}
+
+
/* Given that an actual argument is an SSA_NAME (given in NAME) and is a result
of an assignment statement STMT, try to find out whether NAME can be
described by a (possibly polynomial) pass-through jump-function or an
static void
compute_complex_assign_jump_func (struct ipa_node_params *info,
struct ipa_jump_func *jfunc,
- gimple stmt, tree name)
+ gimple call, gimple stmt, tree name)
{
HOST_WIDE_INT offset, size, max_size;
- tree op1, op2, base, type;
+ tree op1, op2, base, ssa;
int index;
op1 = gimple_assign_rhs1 (stmt);
jfunc->value.pass_through.operation = gimple_assign_rhs_code (stmt);
jfunc->value.pass_through.operand = op2;
}
- else if (gimple_assign_unary_nop_p (stmt))
+ else if (gimple_assign_unary_nop_p (stmt)
+ && !detect_type_change_ssa (op1, call, jfunc))
{
jfunc->type = IPA_JF_PASS_THROUGH;
jfunc->value.pass_through.formal_id = index;
if (TREE_CODE (op1) != ADDR_EXPR)
return;
-
op1 = TREE_OPERAND (op1, 0);
- type = TREE_TYPE (op1);
- if (TREE_CODE (type) != RECORD_TYPE)
+ if (TREE_CODE (TREE_TYPE (op1)) != RECORD_TYPE)
return;
base = get_ref_base_and_extent (op1, &offset, &size, &max_size);
if (TREE_CODE (base) != MEM_REF
|| max_size != size)
return;
offset += mem_ref_offset (base).low * BITS_PER_UNIT;
- base = TREE_OPERAND (base, 0);
- if (TREE_CODE (base) != SSA_NAME
- || !SSA_NAME_IS_DEFAULT_DEF (base)
+ ssa = TREE_OPERAND (base, 0);
+ if (TREE_CODE (ssa) != SSA_NAME
+ || !SSA_NAME_IS_DEFAULT_DEF (ssa)
|| offset < 0)
return;
/* Dynamic types are changed only in constructors and destructors and */
- index = ipa_get_param_decl_index (info, SSA_NAME_VAR (base));
- if (index >= 0)
+ index = ipa_get_param_decl_index (info, SSA_NAME_VAR (ssa));
+ if (index >= 0
+ && !detect_type_change (op1, base, call, jfunc, offset))
{
jfunc->type = IPA_JF_ANCESTOR;
jfunc->value.ancestor.formal_id = index;
jfunc->value.ancestor.offset = offset;
- jfunc->value.ancestor.type = type;
+ jfunc->value.ancestor.type = TREE_TYPE (op1);
}
}
static void
compute_complex_ancestor_jump_func (struct ipa_node_params *info,
struct ipa_jump_func *jfunc,
- gimple phi)
+ gimple call, gimple phi)
{
HOST_WIDE_INT offset, size, max_size;
gimple assign, cond;
basic_block phi_bb, assign_bb, cond_bb;
- tree tmp, parm, expr;
+ tree tmp, parm, expr, obj;
int index, i;
if (gimple_phi_num_args (phi) != 2)
if (TREE_CODE (expr) != ADDR_EXPR)
return;
expr = TREE_OPERAND (expr, 0);
+ obj = expr;
expr = get_ref_base_and_extent (expr, &offset, &size, &max_size);
if (TREE_CODE (expr) != MEM_REF
|| !integer_zerop (gimple_cond_rhs (cond)))
return;
-
phi_bb = gimple_bb (phi);
for (i = 0; i < 2; i++)
{
return;
}
- jfunc->type = IPA_JF_ANCESTOR;
- jfunc->value.ancestor.formal_id = index;
- jfunc->value.ancestor.offset = offset;
- jfunc->value.ancestor.type = TREE_TYPE (TREE_TYPE (tmp));
+ if (!detect_type_change (obj, expr, call, jfunc, offset))
+ {
+ jfunc->type = IPA_JF_ANCESTOR;
+ jfunc->value.ancestor.formal_id = index;
+ jfunc->value.ancestor.offset = offset;
+ jfunc->value.ancestor.type = TREE_TYPE (obj);;
+ }
}
/* Given OP whch is passed as an actual argument to a called function,
and if so, create one and store it to JFUNC. */
static void
-compute_known_type_jump_func (tree op, struct ipa_jump_func *jfunc)
+compute_known_type_jump_func (tree op, struct ipa_jump_func *jfunc,
+ gimple call)
{
HOST_WIDE_INT offset, size, max_size;
tree base, binfo;
|| is_global_var (base))
return;
+ if (detect_type_change (op, base, call, jfunc, offset))
+ return;
+
binfo = TYPE_BINFO (TREE_TYPE (base));
if (!binfo)
return;
{
int index = ipa_get_param_decl_index (info, SSA_NAME_VAR (arg));
- if (index >= 0)
+ if (index >= 0
+ && !detect_type_change_ssa (arg, call, &functions[num]))
{
functions[num].type = IPA_JF_PASS_THROUGH;
functions[num].value.pass_through.formal_id = index;
gimple stmt = SSA_NAME_DEF_STMT (arg);
if (is_gimple_assign (stmt))
compute_complex_assign_jump_func (info, &functions[num],
- stmt, arg);
+ call, stmt, arg);
else if (gimple_code (stmt) == GIMPLE_PHI)
compute_complex_ancestor_jump_func (info, &functions[num],
- stmt);
+ call, stmt);
}
}
else
- compute_known_type_jump_func (arg, &functions[num]);
+ compute_known_type_jump_func (arg, &functions[num], call);
}
}
struct ipa_node_params *info, gimple call,
tree target)
{
+ struct ipa_jump_func jfunc;
tree obj = OBJ_TYPE_REF_OBJECT (target);
tree var;
int index;
var = SSA_NAME_VAR (obj);
index = ipa_get_param_decl_index (info, var);
- if (index >= 0)
+ if (index >= 0
+ && !detect_type_change_ssa (obj, call, &jfunc))
ipa_note_param_call (node, index, call, true);
}
struct param_analysis_info *parms_info;
int i, param_count;
+ push_cfun (DECL_STRUCT_FUNCTION (node->decl));
+ current_function_decl = node->decl;
ipa_initialize_node_params (node);
param_count = ipa_get_param_count (info);
for (i = 0; i < param_count; i++)
if (parms_info[i].visited_statements)
BITMAP_FREE (parms_info[i].visited_statements);
+
+ current_function_decl = NULL;
+ pop_cfun ();
}
projects / gcc.git / commitdiff