Here's an updated patch with your feedback addressed.
Is this version ok?
The common code is in the C++ patch.
---
Implement a C23 clang compatible musttail attribute similar to the earlier
C++ implementation in the C parser.
gcc/c/ChangeLog:
PR c/83324
* c-parser.cc (struct attr_state): Define with musttail_p.
(c_parser_statement_after_labels): Handle [[musttail]].
(c_parser_std_attribute): Dito.
(c_parser_handle_musttail): Dito.
(c_parser_compound_statement_nostart): Dito.
(c_parser_all_labels): Dito.
(c_parser_statement): Dito.
* c-tree.h (c_finish_return): Add musttail_p flag.
* c-typeck.cc (c_finish_return): Handle musttail_p flag.
---
gcc/c/c-parser.cc | 70 ++++++++++++++++++++++++++++++++++++++---------
gcc/c/c-tree.h | 2 +-
gcc/c/c-typeck.cc | 7 +++--
3 files changed, 63 insertions(+), 16 deletions(-)
diff --git a/gcc/c/c-parser.cc b/gcc/c/c-parser.cc
index 8c4e697a4e10..9cb4d5d932ad 100644
--- a/gcc/c/c-parser.cc
+++ b/gcc/c/c-parser.cc
@@ -1621,6 +1621,12 @@ struct omp_for_parse_data {
bool fail : 1;
};
+struct attr_state
+{
+ /* True if we parsed a musttail attribute for return. */
+ bool musttail_p;
+};
+
static bool c_parser_nth_token_starts_std_attributes (c_parser *,
unsigned int);
static tree c_parser_std_attribute_specifier_sequence (c_parser *);
@@ -1665,7 +1671,7 @@ static location_t c_parser_compound_statement_nostart
(c_parser *);
static void c_parser_label (c_parser *, tree);
static void c_parser_statement (c_parser *, bool *, location_t * = NULL);
static void c_parser_statement_after_labels (c_parser *, bool *,
- vec<tree> * = NULL);
+ vec<tree> * = NULL, attr_state =
{});
static tree c_parser_c99_block_statement (c_parser *, bool *,
location_t * = NULL);
static void c_parser_if_statement (c_parser *, bool *, vec<tree> *);
@@ -6982,6 +6988,29 @@ c_parser_handle_directive_omp_attributes (tree &attrs,
}
}
+/* Check if STD_ATTR contains a musttail attribute and remove if it
+ precedes a return. PARSER is the parser and ATTR is the output
+ attr_state. */
+
+static tree
+c_parser_handle_musttail (c_parser *parser, tree std_attrs, attr_state &attr)
+{
+ if (c_parser_next_token_is_keyword (parser, RID_RETURN))
+ {
+ if (lookup_attribute ("gnu", "musttail", std_attrs))
+ {
+ std_attrs = remove_attribute ("gnu", "musttail", std_attrs);
+ attr.musttail_p = true;
+ }
+ if (lookup_attribute ("clang", "musttail", std_attrs))
+ {
+ std_attrs = remove_attribute ("clang", "musttail", std_attrs);
+ attr.musttail_p = true;
+ }
+ }
+ return std_attrs;
+}
+
/* Parse a compound statement except for the opening brace. This is
used for parsing both compound statements and statement expressions
(which follow different paths to handling the opening). */
@@ -6998,6 +7027,7 @@ c_parser_compound_statement_nostart (c_parser *parser)
bool in_omp_loop_block
= omp_for_parse_state ? omp_for_parse_state->want_nested_loop : false;
tree sl = NULL_TREE;
+ attr_state a = {};
if (c_parser_next_token_is (parser, CPP_CLOSE_BRACE))
{
@@ -7138,7 +7168,10 @@ c_parser_compound_statement_nostart (c_parser *parser)
= c_parser_nth_token_starts_std_attributes (parser, 1);
tree std_attrs = NULL_TREE;
if (have_std_attrs)
- std_attrs = c_parser_std_attribute_specifier_sequence (parser);
+ {
+ std_attrs = c_parser_std_attribute_specifier_sequence (parser);
+ std_attrs = c_parser_handle_musttail (parser, std_attrs, a);
+ }
if (c_parser_next_token_is_keyword (parser, RID_CASE)
|| c_parser_next_token_is_keyword (parser, RID_DEFAULT)
|| (c_parser_next_token_is (parser, CPP_NAME)
@@ -7286,7 +7319,7 @@ c_parser_compound_statement_nostart (c_parser *parser)
last_stmt = true;
mark_valid_location_for_stdc_pragma (false);
if (!omp_for_parse_state)
- c_parser_statement_after_labels (parser, NULL);
+ c_parser_statement_after_labels (parser, NULL, NULL, a);
else
{
/* In canonical loop nest form, nested loops can only appear
@@ -7328,15 +7361,20 @@ c_parser_compound_statement_nostart (c_parser *parser)
/* Parse all consecutive labels, possibly preceded by standard
attributes. In this context, a statement is required, not a
declaration, so attributes must be followed by a statement that is
- not just a semicolon. */
+ not just a semicolon. Returns an attr_state. */
-static void
+static attr_state
c_parser_all_labels (c_parser *parser)
{
+ attr_state attr = {};
bool have_std_attrs;
tree std_attrs = NULL;
if ((have_std_attrs = c_parser_nth_token_starts_std_attributes (parser, 1)))
- std_attrs = c_parser_std_attribute_specifier_sequence (parser);
+ {
+ std_attrs = c_parser_std_attribute_specifier_sequence (parser);
+ std_attrs = c_parser_handle_musttail (parser, std_attrs, attr);
+ }
+
while (c_parser_next_token_is_keyword (parser, RID_CASE)
|| c_parser_next_token_is_keyword (parser, RID_DEFAULT)
|| (c_parser_next_token_is (parser, CPP_NAME)
@@ -7346,7 +7384,10 @@ c_parser_all_labels (c_parser *parser)
std_attrs = NULL;
if ((have_std_attrs = c_parser_nth_token_starts_std_attributes (parser,
1)))
- std_attrs = c_parser_std_attribute_specifier_sequence (parser);
+ {
+ std_attrs = c_parser_std_attribute_specifier_sequence (parser);
+ std_attrs = c_parser_handle_musttail (parser, std_attrs, attr);
+ }
}
if (std_attrs
&& (!c_parser_handle_statement_omp_attributes (parser, std_attrs,
&have_std_attrs)
@@ -7358,6 +7399,7 @@ c_parser_all_labels (c_parser *parser)
}
else if (have_std_attrs && c_parser_next_token_is (parser, CPP_SEMICOLON))
c_parser_error (parser, "expected statement");
+ return attr;
}
/* Parse a label (C90 6.6.1, C99 6.8.1, C11 6.8.1).
@@ -7601,11 +7643,11 @@ c_parser_label (c_parser *parser, tree std_attrs)
static void
c_parser_statement (c_parser *parser, bool *if_p, location_t *loc_after_labels)
{
- c_parser_all_labels (parser);
+ attr_state a = c_parser_all_labels (parser);
if (loc_after_labels)
*loc_after_labels = c_parser_peek_token (parser)->location;
parser->omp_attrs_forbidden_p = false;
- c_parser_statement_after_labels (parser, if_p, NULL);
+ c_parser_statement_after_labels (parser, if_p, NULL, a);
}
/* Parse a statement, other than a labeled statement. CHAIN is a vector
@@ -7614,11 +7656,11 @@ c_parser_statement (c_parser *parser, bool *if_p,
location_t *loc_after_labels)
IF_P is used to track whether there's a (possibly labeled) if statement
which is not enclosed in braces and has an else clause. This is used to
- implement -Wparentheses. */
+ implement -Wparentheses. ASTATE is an earlier parsed attribute state. */
static void
c_parser_statement_after_labels (c_parser *parser, bool *if_p,
- vec<tree> *chain)
+ vec<tree> *chain, attr_state astate)
{
location_t loc = c_parser_peek_token (parser)->location;
tree stmt = NULL_TREE;
@@ -7686,7 +7728,8 @@ c_parser_statement_after_labels (c_parser *parser, bool
*if_p,
c_parser_consume_token (parser);
if (c_parser_next_token_is (parser, CPP_SEMICOLON))
{
- stmt = c_finish_return (loc, NULL_TREE, NULL_TREE);
+ stmt = c_finish_return (loc, NULL_TREE, NULL_TREE,
+ astate.musttail_p);
c_parser_consume_token (parser);
}
else
@@ -7695,7 +7738,8 @@ c_parser_statement_after_labels (c_parser *parser, bool
*if_p,
struct c_expr expr = c_parser_expression_conv (parser);
mark_exp_read (expr.value);
stmt = c_finish_return (EXPR_LOC_OR_LOC (expr.value, xloc),
- expr.value, expr.original_type);
+ expr.value, expr.original_type,
+ astate.musttail_p);
goto expect_semicolon;
}
break;
diff --git a/gcc/c/c-tree.h b/gcc/c/c-tree.h
index 15da875a0290..3dc6338bf061 100644
--- a/gcc/c/c-tree.h
+++ b/gcc/c/c-tree.h
@@ -827,7 +827,7 @@ extern tree c_begin_stmt_expr (void);
extern tree c_finish_stmt_expr (location_t, tree);
extern tree c_process_expr_stmt (location_t, tree);
extern tree c_finish_expr_stmt (location_t, tree);
-extern tree c_finish_return (location_t, tree, tree);
+extern tree c_finish_return (location_t, tree, tree, bool = false);
extern tree c_finish_bc_stmt (location_t, tree, bool);
extern tree c_finish_goto_label (location_t, tree);
extern tree c_finish_goto_ptr (location_t, c_expr val);
diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
index ffcab7df4d3b..94b73e3cb0c2 100644
--- a/gcc/c/c-typeck.cc
+++ b/gcc/c/c-typeck.cc
@@ -11693,10 +11693,11 @@ c_finish_goto_ptr (location_t loc, c_expr val)
to return, or a null pointer for `return;' with no value. LOC is
the location of the return statement, or the location of the expression,
if the statement has any. If ORIGTYPE is not NULL_TREE, it
- is the original type of RETVAL. */
+ is the original type of RETVAL. MUSTTAIL_P indicates a musttail
+ attribute. */
tree
-c_finish_return (location_t loc, tree retval, tree origtype)
+c_finish_return (location_t loc, tree retval, tree origtype, bool musttail_p)
{
tree valtype = TREE_TYPE (TREE_TYPE (current_function_decl)), ret_stmt;
bool no_warning = false;
@@ -11710,6 +11711,8 @@ c_finish_return (location_t loc, tree retval, tree
origtype)
warning_at (xloc, 0,
"function declared %<noreturn%> has a %<return%> statement");
+ set_musttail_on_return (retval, xloc, musttail_p);
+
if (retval)
{
tree semantic_type = NULL_TREE;
--
2.45.2
