On 04/12/16 11:19, Jakub Jelinek wrote:
On Tue, Apr 12, 2016 at 10:53:22AM -0400, Jason Merrill wrote:
It doesn't seem that dangerous to me. The decls are only used within
constexpr evaluation, they never escape.
The uids can be used in hashing, folding, for the various on the side
tables (value-expr, debug-expr, ...).
FWIW this proof-of-concept patch showed no testsuite regressions.
nathan
Index: tree.c
===================================================================
--- tree.c (revision 234902)
+++ tree.c (working copy)
@@ -1128,6 +1128,8 @@ free_node (tree node)
/* Return a new node with the same contents as NODE except that its
TREE_CHAIN, if it has one, is zero and it has a fresh uid. */
+bool clone_uid;
+
tree
copy_node_stat (tree node MEM_STAT_DECL)
{
@@ -1149,7 +1151,9 @@ copy_node_stat (tree node MEM_STAT_DECL)
if (TREE_CODE_CLASS (code) == tcc_declaration)
{
- if (code == DEBUG_EXPR_DECL)
+ if (clone_uid)
+ DECL_UID (t) = DECL_UID (node);
+ else if (code == DEBUG_EXPR_DECL)
DECL_UID (t) = --next_debug_decl_uid;
else
{
Index: tree-inline.c
===================================================================
--- tree-inline.c (revision 234902)
+++ tree-inline.c (working copy)
@@ -6100,6 +6100,18 @@ build_duplicate_type (tree type)
return type;
}
+static tree
+copy_decl_no_change_uid (tree decl, copy_body_data *id)
+{
+ extern bool clone_uid;
+
+ clone_uid = true;
+ tree r = copy_decl_no_change (decl, id);
+ clone_uid = false;
+
+ return r;
+}
+
/* Unshare the entire DECL_SAVED_TREE of FN and return the remapped
parameters and RESULT_DECL in PARMS and RESULT. Used by C++ constexpr
evaluation. */
@@ -6120,7 +6132,7 @@ copy_fn (tree fn, tree& parms, tree& res
id.src_cfun = DECL_STRUCT_FUNCTION (fn);
id.decl_map = &decl_map;
- id.copy_decl = copy_decl_no_change;
+ id.copy_decl = copy_decl_no_change_uid;
id.transform_call_graph_edges = CB_CGE_DUPLICATE;
id.transform_new_cfg = false;
id.transform_return_to_modify = false;
