/* A table of all constexpr calls that have been evaluated by the
compiler in this translation unit. */
-static GTY (()) hash_table<constexpr_call_hasher> *constexpr_call_table;
+static GTY ((deletable)) hash_table<constexpr_call_hasher> *constexpr_call_table;
static tree cxx_eval_constant_expression (const constexpr_ctx *, tree,
bool, bool *, bool *, tree * = NULL);
constexpr_call_table = hash_table<constexpr_call_hasher>::create_ggc (101);
}
+/* The representation of a single node in the per-function freelist maintained
+ by FUNDEF_COPIES_TABLE. */
+
+struct fundef_copy
+{
+ tree body;
+ tree parms;
+ tree res;
+ fundef_copy *prev;
+};
+
+/* During constexpr CALL_EXPR evaluation, to avoid issues with sharing when
+ a function happens to get called recursively, we unshare the callee
+ function's body and evaluate this unshared copy instead of evaluating the
+ original body.
+
+ FUNDEF_COPIES_TABLE is a per-function freelist of these unshared function
+ copies. The underlying data structure of FUNDEF_COPIES_TABLE is a hash_map
+ that's keyed off of the original FUNCTION_DECL and whose value is the chain
+ of this function's unused copies awaiting reuse. */
+
+struct fundef_copies_table_t
+{
+ hash_map<tree, fundef_copy *> *map;
+};
+
+static GTY((deletable)) fundef_copies_table_t fundef_copies_table;
+
+/* Initialize FUNDEF_COPIES_TABLE if it's not initialized. */
+
+static void
+maybe_initialize_fundef_copies_table ()
+{
+ if (fundef_copies_table.map == NULL)
+ fundef_copies_table.map = hash_map<tree, fundef_copy *>::create_ggc (101);
+}
+
+/* Reuse a copy or create a new unshared copy of the function FUN.
+ Return this copy. */
+
+static fundef_copy *
+get_fundef_copy (tree fun)
+{
+ maybe_initialize_fundef_copies_table ();
+
+ fundef_copy *copy;
+ fundef_copy **slot = &fundef_copies_table.map->get_or_insert (fun, NULL);
+ if (*slot == NULL)
+ {
+ copy = ggc_alloc<fundef_copy> ();
+ copy->body = copy_fn (fun, copy->parms, copy->res);
+ copy->prev = NULL;
+ }
+ else
+ {
+ copy = *slot;
+ *slot = (*slot)->prev;
+ }
+
+ return copy;
+}
+
+/* Save the copy COPY of function FUN for later reuse by get_fundef_copy(). */
+
+static void
+save_fundef_copy (tree fun, fundef_copy *copy)
+{
+ fundef_copy **slot = &fundef_copies_table.map->get_or_insert (fun, NULL);
+ copy->prev = *slot;
+ *slot = copy;
+}
+
/* We have an expression tree T that represents a call, either CALL_EXPR
or AGGR_INIT_EXPR. If the call is lexically to a named function,
retrun the _DECL for that function. */
if (!result || result == error_mark_node)
{
gcc_assert (DECL_SAVED_TREE (fun));
- tree parms, res;
+ tree body, parms, res;
- /* Unshare the whole function body. */
- tree body = copy_fn (fun, parms, res);
+ /* Reuse or create a new unshared copy of this function's body. */
+ fundef_copy *copy = get_fundef_copy (fun);
+ body = copy->body;
+ parms = copy->parms;
+ res = copy->res;
/* Associate the bindings with the remapped parms. */
tree bound = new_call.bindings;
else
ctx->values->put (res, NULL_TREE);
+ /* Track the callee's evaluated SAVE_EXPRs so that we can forget
+ their values after the call. */
+ constexpr_ctx ctx_with_save_exprs = *ctx;
+ hash_set<tree> save_exprs;
+ ctx_with_save_exprs.save_exprs = &save_exprs;
+
tree jump_target = NULL_TREE;
- cxx_eval_constant_expression (ctx, body,
+ cxx_eval_constant_expression (&ctx_with_save_exprs, body,
lval, non_constant_p, overflow_p,
&jump_target);
}
}
+ /* Forget the saved values of the callee's SAVE_EXPRs. */
+ for (hash_set<tree>::iterator iter = save_exprs.begin();
+ iter != save_exprs.end(); ++iter)
+ ctx_with_save_exprs.values->remove (*iter);
+
/* Remove the parms/result from the values map. Is it worth
bothering to do this when the map itself is only live for
one constexpr evaluation? If so, maybe also clear out
ctx->values->remove (slot);
for (tree parm = parms; parm; parm = TREE_CHAIN (parm))
ctx->values->remove (parm);
+
+ /* Make the unshared function copy we used available for re-use. */
+ save_fundef_copy (fun, copy);
}
if (result == error_mark_node)