From: Andi Kleen <ak@gcc.gnu.org>
Date: Sat, 20 Jul 2024 23:07:41 +0000 (-0700)
Subject: Revert "C++: Support clang compatible [[musttail]] (PR83324)"
X-Git-Tag: basepoints/gcc-16~7376
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ff6994e483be5bd340bfacc50d3441bd21aba1c4;p=thirdparty%2Fgcc.git

Revert "C++: Support clang compatible [[musttail]] (PR83324)"

This reverts commit 59dd1d7ab21ad9a7ebf641ec9aeea609c003ad2f.
---

diff --git a/gcc/c-family/c-attribs.cc b/gcc/c-family/c-attribs.cc
index 685f212683f..5adc7b775ea 100644
--- a/gcc/c-family/c-attribs.cc
+++ b/gcc/c-family/c-attribs.cc
@@ -672,26 +672,6 @@ attribute_takes_identifier_p (const_tree attr_id)
     return targetm.attribute_takes_identifier_p (attr_id);
 }
 
-/* Set a musttail attribute MUSTTAIL_P on return expression RETVAL
-   at LOC.  */
-
-void
-set_musttail_on_return (tree retval, location_t loc, bool musttail_p)
-{
-  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 (loc, "cannot tail-call: return value must be a call");
-      else
-	CALL_EXPR_MUST_TAIL_CALL (t) = 1;
-    }
-  else if (musttail_p && !retval)
-    error_at (loc, "cannot tail-call: return value must be a call");
-}
-
 /* Verify that argument value POS at position ARGNO to attribute NAME
    applied to function FN (which is either a function declaration or function
    type) refers to a function parameter at position POS and the expected type
diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h
index 2510ee4dbc9..adee822a3ae 100644
--- a/gcc/c-family/c-common.h
+++ b/gcc/c-family/c-common.h
@@ -1648,7 +1648,6 @@ extern tree handle_noreturn_attribute (tree *, tree, tree, int, bool *);
 extern tree handle_musttail_attribute (tree *, tree, tree, int, bool *);
 extern bool has_attribute (location_t, tree, tree, tree (*)(tree));
 extern tree build_attr_access_from_parms (tree, bool);
-extern void set_musttail_on_return (tree, location_t, bool);
 
 /* In c-format.cc.  */
 extern bool valid_format_string_type_p (tree);
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index c6728328bc6..609d8941cf7 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -4236,10 +4236,6 @@ templated_operator_saved_lookups (tree t)
 #define AGGR_INIT_FROM_THUNK_P(NODE) \
   (AGGR_INIT_EXPR_CHECK (NODE)->base.protected_flag)
 
-/* Nonzero means that the call was marked musttail.  */
-#define AGGR_INIT_EXPR_MUST_TAIL(NODE) \
-  (AGGR_INIT_EXPR_CHECK (NODE)->base.static_flag)
-
 /* AGGR_INIT_EXPR accessors.  These are equivalent to the CALL_EXPR
    accessors, except for AGGR_INIT_EXPR_SLOT (which takes the place of
    CALL_EXPR_STATIC_CHAIN).  */
diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index 1fa0780944b..efd5d6f29a7 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -2467,7 +2467,7 @@ static tree cp_parser_perform_range_for_lookup
 static tree cp_parser_range_for_member_function
   (tree, tree);
 static tree cp_parser_jump_statement
-  (cp_parser *, tree &);
+  (cp_parser *);
 static void cp_parser_declaration_statement
   (cp_parser *);
 
@@ -12757,7 +12757,7 @@ cp_parser_statement (cp_parser* parser, tree in_statement_expr,
 	case RID_CO_RETURN:
 	case RID_GOTO:
 	  std_attrs = process_stmt_hotness_attribute (std_attrs, attrs_loc);
-	  statement = cp_parser_jump_statement (parser, std_attrs);
+	  statement = cp_parser_jump_statement (parser);
 	  break;
 
 	  /* Objective-C++ exception-handling constructs.  */
@@ -14845,11 +14845,10 @@ cp_parser_init_statement (cp_parser *parser, tree *decl)
    jump-statement:
      goto * expression ;
 
-   STD_ATTRS are the statement attributes. They can be modified.
    Returns the new BREAK_STMT, CONTINUE_STMT, RETURN_EXPR, or GOTO_EXPR.  */
 
 static tree
-cp_parser_jump_statement (cp_parser* parser, tree &std_attrs)
+cp_parser_jump_statement (cp_parser* parser)
 {
   tree statement = error_mark_node;
   cp_token *token;
@@ -14926,31 +14925,6 @@ cp_parser_jump_statement (cp_parser* parser, tree &std_attrs)
 	  /* If the next token is a `;', then there is no
 	     expression.  */
 	  expr = NULL_TREE;
-
-	if (keyword == RID_RETURN)
-	  {
-	    bool musttail_p = false;
-	    if (lookup_attribute ("gnu", "musttail", std_attrs))
-	      {
-		musttail_p = true;
-		std_attrs = remove_attribute ("gnu", "musttail", std_attrs);
-	      }
-	    /* Support this for compatibility.  */
-	    if (lookup_attribute ("clang", "musttail", std_attrs))
-	      {
-		musttail_p = true;
-		std_attrs = remove_attribute ("clang", "musttail", std_attrs);
-	      }
-
-	    tree ret_expr = expr;
-	    if (ret_expr && TREE_CODE (ret_expr) == TARGET_EXPR)
-	      ret_expr = TARGET_EXPR_INITIAL (ret_expr);
-	    if (ret_expr && TREE_CODE (ret_expr) == AGGR_INIT_EXPR)
-	      AGGR_INIT_EXPR_MUST_TAIL (ret_expr) = musttail_p;
-	    else
-	      set_musttail_on_return (expr, token->location, musttail_p);
-	  }
-
 	/* Build the return-statement, check co-return first, since type
 	   deduction is not valid there.  */
 	if (keyword == RID_CO_RETURN)
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 9fae3000203..108e929b8ee 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -21094,19 +21094,12 @@ 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 = false;
-	    if (TREE_CODE (t) == CALL_EXPR)
-	      mtc = CALL_EXPR_MUST_TAIL_CALL (t);
-	    if (op || ord || rev || mtc)
+	    if (op || ord || rev)
 	      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;
-		  if (TREE_CODE (call) == CALL_EXPR)
-		    CALL_EXPR_MUST_TAIL_CALL (call) = mtc;
-		  else if (TREE_CODE (call) == AGGR_INIT_EXPR)
-		    AGGR_INIT_EXPR_MUST_TAIL (call) = mtc;
 		}
 	    if (warning_suppressed_p (t, OPT_Wpessimizing_move))
 	      /* This also suppresses -Wredundant-move.  */
diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index 0f122b839c5..c21572e5d7f 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -4979,7 +4979,6 @@ simplify_aggr_init_expr (tree *tp)
     = CALL_EXPR_OPERATOR_SYNTAX (aggr_init_expr);
   CALL_EXPR_ORDERED_ARGS (call_expr) = CALL_EXPR_ORDERED_ARGS (aggr_init_expr);
   CALL_EXPR_REVERSE_ARGS (call_expr) = CALL_EXPR_REVERSE_ARGS (aggr_init_expr);
-  CALL_EXPR_MUST_TAIL_CALL (call_expr) = AGGR_INIT_EXPR_MUST_TAIL (aggr_init_expr);
 
   if (style == ctor)
     {