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X-IronPort-AV: E=McAfee;i="6600,9927,10971"; a="3942950" X-IronPort-AV: E=Sophos;i="6.05,237,1701158400"; d="scan'208";a="3942950" Received: from fmviesa002.fm.intel.com ([10.60.135.142]) by fmvoesa106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Feb 2024 01:13:30 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.05,237,1701158400"; d="scan'208";a="23318064" Received: from tassilo.jf.intel.com ([10.54.38.190]) by fmviesa002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Feb 2024 01:13:30 -0800 From: Andi Kleen To: gcc-patches@gnu.org Cc: Andi Kleen Subject: [PATCH v4 3/5] C: Implement musttail attribute for returns Date: Fri, 2 Feb 2024 01:09:18 -0800 Message-ID: <20240202091322.1898280-4-ak@linux.intel.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240202091322.1898280-1-ak@linux.intel.com> References: <20240202091322.1898280-1-ak@linux.intel.com> MIME-Version: 1.0 Received-SPF: none client-ip=192.198.163.12; envelope-from=ak@linux.intel.com; helo=mgamail.intel.com X-Spam_score_int: -32 X-Spam_score: -3.3 X-Spam_bar: --- X-Spam_report: (-3.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.292, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_NONE=0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-Spam-Status: No, score=-13.0 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_EF, GIT_PATCH_0, SPF_HELO_PASS, SPF_NONE, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: gcc-patches-bounces+incoming=patchwork.ozlabs.org@gcc.gnu.org Implement a C23 clang compatible musttail attribute similar to the earlier C++ implementation in the C parser. PR83324 gcc/c/ChangeLog: * 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 | 61 +++++++++++++++++++++++++++++++++++++---------- gcc/c/c-tree.h | 2 +- gcc/c/c-typeck.cc | 15 ++++++++++-- 3 files changed, 63 insertions(+), 15 deletions(-) diff --git a/gcc/c/c-parser.cc b/gcc/c/c-parser.cc index c31349dae2ff..76931931e270 100644 --- a/gcc/c/c-parser.cc +++ b/gcc/c/c-parser.cc @@ -1616,6 +1616,11 @@ struct omp_for_parse_data { bool fail : 1; }; +struct attr_state +{ + bool musttail_p; // parsed a musttail for return +}; + static bool c_parser_nth_token_starts_std_attributes (c_parser *, unsigned int); static tree c_parser_std_attribute_specifier_sequence (c_parser *); @@ -1660,7 +1665,7 @@ 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 * = NULL); + vec * = 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 *); @@ -5757,6 +5762,8 @@ c_parser_std_attribute (c_parser *parser, bool for_tm, } goto out; } + else if (is_attribute_p ("musttail", name)) + error ("% attribute has arguments"); { location_t open_loc = c_parser_peek_token (parser)->location; matching_parens parens; @@ -6943,6 +6950,28 @@ c_parser_handle_directive_omp_attributes (tree &attrs, } } +/* Check if STD_ATTR contains a musttail attribute and handle it + PARSER is the parser and A is the output attr_state. */ + +static tree +c_parser_handle_musttail (c_parser *parser, tree std_attrs, attr_state &a) +{ + 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); + a.musttail_p = true; + } + if (lookup_attribute ("clang", "musttail", std_attrs)) + { + std_attrs = remove_attribute ("clang", "musttail", std_attrs); + a.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). */ @@ -6959,6 +6988,7 @@ 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)) { @@ -7097,7 +7127,10 @@ 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) @@ -7245,7 +7278,7 @@ 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 @@ -7287,15 +7320,18 @@ 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 a = {}; 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_handle_musttail (parser, + c_parser_std_attribute_specifier_sequence (parser), a); + 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) @@ -7317,6 +7353,7 @@ 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 a; } /* Parse a label (C90 6.6.1, C99 6.8.1, C11 6.8.1). @@ -7560,11 +7597,11 @@ 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 @@ -7573,11 +7610,11 @@ 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. A has an earlier parsed attribute state. */ static void c_parser_statement_after_labels (c_parser *parser, bool *if_p, - vec *chain) + vec *chain, attr_state a) { location_t loc = c_parser_peek_token (parser)->location; tree stmt = NULL_TREE; @@ -7645,7 +7682,7 @@ 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, a.musttail_p); c_parser_consume_token (parser); } else @@ -7654,7 +7691,7 @@ 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, a.musttail_p); goto expect_semicolon; } break; diff --git a/gcc/c/c-tree.h b/gcc/c/c-tree.h index 1fba9c8dae76..efea9e913a50 100644 --- a/gcc/c/c-tree.h +++ b/gcc/c/c-tree.h @@ -825,7 +825,7 @@ 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 3b519c48ae0a..695f1d519770 100644 --- a/gcc/c/c-typeck.cc +++ b/gcc/c/c-typeck.cc @@ -11443,10 +11443,10 @@ 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; @@ -11460,6 +11460,17 @@ c_finish_return (location_t loc, tree retval, tree origtype) warning_at (xloc, 0, "function declared % has a % statement"); + if (retval && musttail_p) + { + tree t = retval; + if (TREE_CODE (t) == TARGET_EXPR) + t = TARGET_EXPR_INITIAL (t); + if (TREE_CODE (t) != CALL_EXPR) + error_at (xloc, "cannot tail-call: return value must be call"); + else + CALL_EXPR_MUST_TAIL_CALL (t) = 1; + } + if (retval) { tree semantic_type = NULL_TREE;