On 6/3/24 15:35, Andi Kleen wrote:
On Mon, Jun 03, 2024 at 12:29:28PM -0400, Jason Merrill wrote:
On 6/3/24 11:44, Jakub Jelinek wrote:
On Mon, Jun 03, 2024 at 08:33:52AM -0700, Andi Kleen wrote:
On Mon, Jun 03, 2024 at 10:42:20AM -0400, Jason Merrill wrote:
@@ -30316,7 +30348,7 @@ cp_parser_std_attribute (cp_parser *parser, tree
attr_ns)
/* Maybe we don't expect to see any arguments for this attribute. */
const attribute_spec *as
= lookup_attribute_spec (TREE_PURPOSE (attribute));
- if (as && as->max_length == 0)
+ if ((as && as->max_length == 0) || is_attribute_p ("musttail", attr_id))
This shouldn't be necessary with the attribute in the c-attribs table,
right? This patch is OK without this hunk and with the comment tweak above.
Yes I will remove it. Also the hunk above can be simplified, we don't
need the extra case anymore.
But unfortunately there's another problem (sorry I missed that earlier
but the Linaro bot pointed it out again):
This hunk:
@@ -21085,12 +21085,14 @@ tsubst_expr (tree t, tree args, tsubst_flags_t
complain, tree in_decl)
bool op = CALL_EXPR_OPERATOR_SYNTAX (t);
bool ord = CALL_EXPR_ORDERED_ARGS (t);
bool rev = CALL_EXPR_REVERSE_ARGS (t);
- if (op || ord || rev)
+ bool mtc = CALL_EXPR_MUST_TAIL_CALL (t);
+ if (op || ord || rev || mtc)
if (tree call = extract_call_expr (ret))
{
CALL_EXPR_OPERATOR_SYNTAX (call) = op;
CALL_EXPR_ORDERED_ARGS (call) = ord;
CALL_EXPR_REVERSE_ARGS (call) = rev;
+ CALL_EXPR_MUST_TAIL_CALL (call) = mtc;
}
The difference is that CALL_EXPR_MUST_TAIL_CALL is defined as:
#define CALL_EXPR_MUST_TAIL_CALL(NODE) \
(CALL_EXPR_CHECK (NODE)->base.static_flag)
while the others like:
#define CALL_EXPR_ORDERED_ARGS(NODE) \
TREE_LANG_FLAG_3 (CALL_OR_AGGR_INIT_CHECK (NODE))
where
#define CALL_OR_AGGR_INIT_CHECK(NODE) \
TREE_CHECK2 ((NODE), CALL_EXPR, AGGR_INIT_EXPR)
while
#define CALL_EXPR_CHECK(t) TREE_CHECK (t, CALL_EXPR)
(this one is defined in generated tree-check.h).
So, while the CALL_EXPR_REVERSE_ARGS etc. can be used on either
CALL_EXPR or AGGR_INIT_EXPR (the latter is a C++ specific tree code),
CALL_EXPR_MUST_TAIL_CALL is allowed only on CALL_EXPR.
AGGR_INIT_EXPR is used for C++ constructor calls, so I think
they really don't need such a flag
AGGR_INIT_EXPR is also used for functions returning a class, so I think it
is needed.
I used this variant which passes tests. It assumes that there are no
wrapped calls with this flag, but I assume that's ok.
musttail10.C should also check the case where the function called with
[[musttail]] returns a non-trivially-copyable class (e.g. that has a
destructor).
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index f6af8e1a81e4..c50fea4282e4 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -21085,14 +21085,17 @@ tsubst_expr (tree t, tree args, tsubst_flags_t
complain, tree in_decl)
bool op = CALL_EXPR_OPERATOR_SYNTAX (t);
bool ord = CALL_EXPR_ORDERED_ARGS (t);
bool rev = CALL_EXPR_REVERSE_ARGS (t);
- bool mtc = CALL_EXPR_MUST_TAIL_CALL (t);
+ bool mtc = false;
+ if (TREE_CODE (t) == CALL_EXPR)
+ mtc = CALL_EXPR_MUST_TAIL_CALL (t);
if (op || ord || rev || mtc)
if (tree call = extract_call_expr (ret))
{
CALL_EXPR_OPERATOR_SYNTAX (call) = op;
CALL_EXPR_ORDERED_ARGS (call) = ord;
CALL_EXPR_REVERSE_ARGS (call) = rev;
- CALL_EXPR_MUST_TAIL_CALL (call) = mtc;
+ if (TREE_CODE (call) == CALL_EXPR)
+ CALL_EXPR_MUST_TAIL_CALL (call) = mtc;
}
if (warning_suppressed_p (t, OPT_Wpessimizing_move))
/* This also suppresses -Wredundant-move. */
