On 3/26/23 12:54, Iain Sandoe wrote:
Tested on x86_64-darwin21, x86-64-linux-gnu
OK for trunk?
Iain
When we need to 'promote' a value (i.e. store it in the coroutine frame) it
is given a frame entry name. This was based on the DECL_UID for slot vars.
However, when LTO is used, the names from multiple TUs become visible at the
same time, and the DECL_UIDs usually differ between units. This leads to a
"ODR mismatch" warning for the frame type.
The fix here is to use a counter instead of the DECL_UID which makes a name
that is stable between TUs for each frame layout (one per coroutine func).
Signed-off-by: Iain Sandoe <i...@sandoe.co.uk>
PR c++/101118
gcc/cp/ChangeLog:
* coroutines.cc: Add counter for promoted slot vars.
(flatten_await_stmt): Use slot vars counter instead of DECL_UID
to generate the frame entry name for promoted target expression
slot variables.
(morph_fn_to_coro): Reset the slot vars counter at the start of
each coroutine function.
---
gcc/cp/coroutines.cc | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
index a2189e43db8..359a5bf46ff 100644
--- a/gcc/cp/coroutines.cc
+++ b/gcc/cp/coroutines.cc
@@ -2726,6 +2726,11 @@ struct var_nest_node
var_nest_node *else_cl;
};
+/* This is used to make a stable, but unique-per-function, sequence number for
+ each TARGET_EXPR slot variable that we 'promote' to a frame entry. It needs
+ to be stable because the frame type is visible to LTO ODR checking. */
+static unsigned tmpno = 0;
How about using temps_used->elements() for the index instead of a
separate static counter?
/* This is called for single statements from the co-await statement walker.
It checks to see if the statement contains any initializers for awaitables
and if any of these capture items by reference. */
@@ -2889,7 +2894,7 @@ flatten_await_stmt (var_nest_node *n, hash_set<tree>
*promoted,
tree init = t;
temps_used->add (init);
tree var_type = TREE_TYPE (init);
- char *buf = xasprintf ("D.%d", DECL_UID (TREE_OPERAND (init, 0)));
+ char *buf = xasprintf ("T%03u", tmpno++);
tree var = build_lang_decl (VAR_DECL, get_identifier (buf), var_type);
DECL_ARTIFICIAL (var) = true;
free (buf);
@@ -4374,6 +4379,7 @@ morph_fn_to_coro (tree orig, tree *resumer, tree
*destroyer)
{
gcc_checking_assert (orig && TREE_CODE (orig) == FUNCTION_DECL);
+ tmpno = 0;
*resumer = error_mark_node;
*destroyer = error_mark_node;
if (!coro_function_valid_p (orig))
