diff mbox series

[2/19,front-end] C/C++ front-end: add pragma GCC novector

Message ID ZJw4msITSZSb83WR@arm.com
State New
Headers show
Series Support early break/return auto-vectorization | expand

Commit Message

Tamar Christina June 28, 2023, 1:41 p.m. UTC
Hi All,

FORTRAN currently has a pragma NOVECTOR for indicating that vectorization should
not be applied to a particular loop.

ICC/ICX also has such a pragma for C and C++ called #pragma novector.

As part of this patch series I need a way to easily turn off vectorization of
particular loops, particularly for testsuite reasons.

This patch proposes a #pragma GCC novector that does the same for C and C++
as gfortan does for FORTRAN and what ICX/ICX does for C and C++.

I added only some basic tests here, but the next patch in the series uses this
in the testsuite in about ~800 tests.

Bootstrapped Regtested on aarch64-none-linux-gnu and no issues.

Ok for master?

Thanks,
Tamar

gcc/c-family/ChangeLog:

	* c-pragma.h (enum pragma_kind): Add PRAGMA_NOVECTOR.
	* c-pragma.cc (init_pragma): Use it.

gcc/c/ChangeLog:

	* c-parser.cc (c_parser_while_statement, c_parser_do_statement,
	c_parser_for_statement, c_parser_statement_after_labels,
	c_parse_pragma_novector, c_parser_pragma): Wire through novector and
	default to false.

gcc/cp/ChangeLog:

	* cp-tree.def (RANGE_FOR_STMT): Update comment.
	* cp-tree.h (RANGE_FOR_NOVECTOR): New.
	(cp_convert_range_for, finish_while_stmt_cond, finish_do_stmt,
	finish_for_cond): Add novector param.
	* init.cc (build_vec_init): Default novector to false.
	* method.cc (build_comparison_op): Likewise.
	* parser.cc (cp_parser_statement): Likewise.
	(cp_parser_for, cp_parser_c_for, cp_parser_range_for,
	cp_convert_range_for, cp_parser_iteration_statement,
	cp_parser_omp_for_loop, cp_parser_pragma): Support novector.
	(cp_parser_pragma_novector): New.
	* pt.cc (tsubst_expr): Likewise.
	* semantics.cc (finish_while_stmt_cond, finish_do_stmt,
	finish_for_cond): Likewise.

gcc/ChangeLog:

	* doc/extend.texi: Document it.
	* tree-core.h (struct tree_base): Add lang_flag_7 and reduce spare0.
	* tree.h (TREE_LANG_FLAG_7): New.

gcc/testsuite/ChangeLog:

	* g++.dg/vect/vect-novector-pragma.cc: New test.
	* gcc.dg/vect/vect-novector-pragma.c: New test.

--- inline copy of patch -- 
diff --git a/gcc/c-family/c-pragma.h b/gcc/c-family/c-pragma.h
index 9cc95ab3ee376628dbef2485b84e6008210fa8fc..99cf2e8bd1c05537c198470f1aaa0a5a9da4e576 100644




--
diff --git a/gcc/c-family/c-pragma.h b/gcc/c-family/c-pragma.h
index 9cc95ab3ee376628dbef2485b84e6008210fa8fc..99cf2e8bd1c05537c198470f1aaa0a5a9da4e576 100644
--- a/gcc/c-family/c-pragma.h
+++ b/gcc/c-family/c-pragma.h
@@ -87,6 +87,7 @@ enum pragma_kind {
   PRAGMA_GCC_PCH_PREPROCESS,
   PRAGMA_IVDEP,
   PRAGMA_UNROLL,
+  PRAGMA_NOVECTOR,
 
   PRAGMA_FIRST_EXTERNAL
 };
diff --git a/gcc/c-family/c-pragma.cc b/gcc/c-family/c-pragma.cc
index 0d2b333cebbed32423d5dc6fd2a3ac0ce0bf8b94..848a850b8e123ff1c6ae1ec4b7f8ccbd599b1a88 100644
--- a/gcc/c-family/c-pragma.cc
+++ b/gcc/c-family/c-pragma.cc
@@ -1862,6 +1862,10 @@ init_pragma (void)
     cpp_register_deferred_pragma (parse_in, "GCC", "unroll", PRAGMA_UNROLL,
 				  false, false);
 
+  if (!flag_preprocess_only)
+    cpp_register_deferred_pragma (parse_in, "GCC", "novector", PRAGMA_NOVECTOR,
+				  false, false);
+
 #ifdef HANDLE_PRAGMA_PACK_WITH_EXPANSION
   c_register_pragma_with_expansion (0, "pack", handle_pragma_pack);
 #else
diff --git a/gcc/c/c-parser.cc b/gcc/c/c-parser.cc
index 24a6eb6e4596f32c477e3f1c3f98b9792f7bc92c..9d35fe68704c8aca197bcd4805a146c655959621 100644
--- a/gcc/c/c-parser.cc
+++ b/gcc/c/c-parser.cc
@@ -1572,9 +1572,11 @@ static tree c_parser_c99_block_statement (c_parser *, bool *,
 					  location_t * = NULL);
 static void c_parser_if_statement (c_parser *, bool *, vec<tree> *);
 static void c_parser_switch_statement (c_parser *, bool *);
-static void c_parser_while_statement (c_parser *, bool, unsigned short, bool *);
-static void c_parser_do_statement (c_parser *, bool, unsigned short);
-static void c_parser_for_statement (c_parser *, bool, unsigned short, bool *);
+static void c_parser_while_statement (c_parser *, bool, unsigned short, bool,
+				      bool *);
+static void c_parser_do_statement (c_parser *, bool, unsigned short, bool);
+static void c_parser_for_statement (c_parser *, bool, unsigned short, bool,
+				    bool *);
 static tree c_parser_asm_statement (c_parser *);
 static tree c_parser_asm_operands (c_parser *);
 static tree c_parser_asm_goto_operands (c_parser *);
@@ -6644,13 +6646,13 @@ c_parser_statement_after_labels (c_parser *parser, bool *if_p,
 	  c_parser_switch_statement (parser, if_p);
 	  break;
 	case RID_WHILE:
-	  c_parser_while_statement (parser, false, 0, if_p);
+	  c_parser_while_statement (parser, false, 0, false, if_p);
 	  break;
 	case RID_DO:
-	  c_parser_do_statement (parser, false, 0);
+	  c_parser_do_statement (parser, false, 0, false);
 	  break;
 	case RID_FOR:
-	  c_parser_for_statement (parser, false, 0, if_p);
+	  c_parser_for_statement (parser, false, 0, false, if_p);
 	  break;
 	case RID_GOTO:
 	  c_parser_consume_token (parser);
@@ -7146,7 +7148,7 @@ c_parser_switch_statement (c_parser *parser, bool *if_p)
 
 static void
 c_parser_while_statement (c_parser *parser, bool ivdep, unsigned short unroll,
-			  bool *if_p)
+			  bool novector, bool *if_p)
 {
   tree block, cond, body;
   unsigned char save_in_statement;
@@ -7168,6 +7170,11 @@ c_parser_while_statement (c_parser *parser, bool ivdep, unsigned short unroll,
 		   build_int_cst (integer_type_node,
 				  annot_expr_unroll_kind),
 		   build_int_cst (integer_type_node, unroll));
+  if (novector && cond != error_mark_node)
+    cond = build3 (ANNOTATE_EXPR, TREE_TYPE (cond), cond,
+		   build_int_cst (integer_type_node,
+				  annot_expr_no_vector_kind),
+		   integer_zero_node);
   save_in_statement = in_statement;
   in_statement = IN_ITERATION_STMT;
 
@@ -7199,7 +7206,8 @@ c_parser_while_statement (c_parser *parser, bool ivdep, unsigned short unroll,
 */
 
 static void
-c_parser_do_statement (c_parser *parser, bool ivdep, unsigned short unroll)
+c_parser_do_statement (c_parser *parser, bool ivdep, unsigned short unroll,
+		       bool novector)
 {
   tree block, cond, body;
   unsigned char save_in_statement;
@@ -7228,6 +7236,11 @@ c_parser_do_statement (c_parser *parser, bool ivdep, unsigned short unroll)
 		   build_int_cst (integer_type_node,
 				  annot_expr_unroll_kind),
  		   build_int_cst (integer_type_node, unroll));
+  if (novector && cond != error_mark_node)
+    cond = build3 (ANNOTATE_EXPR, TREE_TYPE (cond), cond,
+		   build_int_cst (integer_type_node,
+				  annot_expr_no_vector_kind),
+		   integer_zero_node);
   if (!c_parser_require (parser, CPP_SEMICOLON, "expected %<;%>"))
     c_parser_skip_to_end_of_block_or_statement (parser);
 
@@ -7296,7 +7309,7 @@ c_parser_do_statement (c_parser *parser, bool ivdep, unsigned short unroll)
 
 static void
 c_parser_for_statement (c_parser *parser, bool ivdep, unsigned short unroll,
-			bool *if_p)
+			bool novector, bool *if_p)
 {
   tree block, cond, incr, body;
   unsigned char save_in_statement;
@@ -7430,6 +7443,12 @@ c_parser_for_statement (c_parser *parser, bool ivdep, unsigned short unroll,
 					  "with %<GCC unroll%> pragma");
 		  cond = error_mark_node;
 		}
+	      else if (novector)
+		{
+		  c_parser_error (parser, "missing loop condition in loop "
+					  "with %<GCC novector%> pragma");
+		  cond = error_mark_node;
+		}
 	      else
 		{
 		  c_parser_consume_token (parser);
@@ -7452,6 +7471,11 @@ c_parser_for_statement (c_parser *parser, bool ivdep, unsigned short unroll,
  			   build_int_cst (integer_type_node,
 					  annot_expr_unroll_kind),
 			   build_int_cst (integer_type_node, unroll));
+	  if (novector && cond != error_mark_node)
+	    cond = build3 (ANNOTATE_EXPR, TREE_TYPE (cond), cond,
+			   build_int_cst (integer_type_node,
+					  annot_expr_no_vector_kind),
+			   integer_zero_node);
 	}
       /* Parse the increment expression (the third expression in a
 	 for-statement).  In the case of a foreach-statement, this is
@@ -13037,6 +13061,16 @@ c_parse_pragma_ivdep (c_parser *parser)
   return true;
 }
 
+/* Parse a pragma GCC novector.  */
+
+static bool
+c_parse_pragma_novector (c_parser *parser)
+{
+  c_parser_consume_pragma (parser);
+  c_parser_skip_to_pragma_eol (parser);
+  return true;
+}
+
 /* Parse a pragma GCC unroll.  */
 
 static unsigned short
@@ -13264,11 +13298,12 @@ c_parser_pragma (c_parser *parser, enum pragma_context context, bool *if_p)
     case PRAGMA_IVDEP:
       {
 	const bool ivdep = c_parse_pragma_ivdep (parser);
-	unsigned short unroll;
+	unsigned short unroll = 0;
+	bool novector = false;
 	if (c_parser_peek_token (parser)->pragma_kind == PRAGMA_UNROLL)
 	  unroll = c_parser_pragma_unroll (parser);
-	else
-	  unroll = 0;
+	if (c_parser_peek_token (parser)->pragma_kind == PRAGMA_NOVECTOR)
+	  novector = c_parse_pragma_novector (parser);
 	if (!c_parser_next_token_is_keyword (parser, RID_FOR)
 	    && !c_parser_next_token_is_keyword (parser, RID_WHILE)
 	    && !c_parser_next_token_is_keyword (parser, RID_DO))
@@ -13277,22 +13312,48 @@ c_parser_pragma (c_parser *parser, enum pragma_context context, bool *if_p)
 	    return false;
 	  }
 	if (c_parser_next_token_is_keyword (parser, RID_FOR))
-	  c_parser_for_statement (parser, ivdep, unroll, if_p);
+	  c_parser_for_statement (parser, ivdep, unroll, novector, if_p);
 	else if (c_parser_next_token_is_keyword (parser, RID_WHILE))
-	  c_parser_while_statement (parser, ivdep, unroll, if_p);
+	  c_parser_while_statement (parser, ivdep, unroll, novector, if_p);
 	else
-	  c_parser_do_statement (parser, ivdep, unroll);
+	  c_parser_do_statement (parser, ivdep, unroll, novector);
       }
       return true;
 
     case PRAGMA_UNROLL:
       {
 	unsigned short unroll = c_parser_pragma_unroll (parser);
-	bool ivdep;
+	bool ivdep = false;
+	bool novector = false;
 	if (c_parser_peek_token (parser)->pragma_kind == PRAGMA_IVDEP)
 	  ivdep = c_parse_pragma_ivdep (parser);
+	if (c_parser_peek_token (parser)->pragma_kind == PRAGMA_NOVECTOR)
+	  novector = c_parse_pragma_novector (parser);
+	if (!c_parser_next_token_is_keyword (parser, RID_FOR)
+	    && !c_parser_next_token_is_keyword (parser, RID_WHILE)
+	    && !c_parser_next_token_is_keyword (parser, RID_DO))
+	  {
+	    c_parser_error (parser, "for, while or do statement expected");
+	    return false;
+	  }
+	if (c_parser_next_token_is_keyword (parser, RID_FOR))
+	  c_parser_for_statement (parser, ivdep, unroll, novector, if_p);
+	else if (c_parser_next_token_is_keyword (parser, RID_WHILE))
+	  c_parser_while_statement (parser, ivdep, unroll, novector, if_p);
 	else
-	  ivdep = false;
+	  c_parser_do_statement (parser, ivdep, unroll, novector);
+      }
+      return true;
+
+    case PRAGMA_NOVECTOR:
+      {
+	bool novector = c_parse_pragma_novector (parser);
+	unsigned short unroll = 0;
+	bool ivdep = false;
+	if (c_parser_peek_token (parser)->pragma_kind == PRAGMA_IVDEP)
+	  ivdep = c_parse_pragma_ivdep (parser);
+	if (c_parser_peek_token (parser)->pragma_kind == PRAGMA_UNROLL)
+	  unroll = c_parser_pragma_unroll (parser);
 	if (!c_parser_next_token_is_keyword (parser, RID_FOR)
 	    && !c_parser_next_token_is_keyword (parser, RID_WHILE)
 	    && !c_parser_next_token_is_keyword (parser, RID_DO))
@@ -13301,11 +13362,11 @@ c_parser_pragma (c_parser *parser, enum pragma_context context, bool *if_p)
 	    return false;
 	  }
 	if (c_parser_next_token_is_keyword (parser, RID_FOR))
-	  c_parser_for_statement (parser, ivdep, unroll, if_p);
+	  c_parser_for_statement (parser, ivdep, unroll, novector, if_p);
 	else if (c_parser_next_token_is_keyword (parser, RID_WHILE))
-	  c_parser_while_statement (parser, ivdep, unroll, if_p);
+	  c_parser_while_statement (parser, ivdep, unroll, novector, if_p);
 	else
-	  c_parser_do_statement (parser, ivdep, unroll);
+	  c_parser_do_statement (parser, ivdep, unroll, novector);
       }
       return true;
 
diff --git a/gcc/cp/cp-tree.def b/gcc/cp/cp-tree.def
index 0e66ca70e00caa1dc4beada1024ace32954e2aaf..c13c8ea98a523c4ef1c55a11e02d5da9db7e367e 100644
--- a/gcc/cp/cp-tree.def
+++ b/gcc/cp/cp-tree.def
@@ -305,8 +305,8 @@ DEFTREECODE (IF_STMT, "if_stmt", tcc_statement, 4)
 
 /* Used to represent a range-based `for' statement. The operands are
    RANGE_FOR_DECL, RANGE_FOR_EXPR, RANGE_FOR_BODY, RANGE_FOR_SCOPE,
-   RANGE_FOR_UNROLL, and RANGE_FOR_INIT_STMT, respectively.  Only used in
-   templates.  */
+   RANGE_FOR_UNROLL, RANGE_FOR_NOVECTOR and RANGE_FOR_INIT_STMT,
+   respectively.  Only used in templates.  */
 DEFTREECODE (RANGE_FOR_STMT, "range_for_stmt", tcc_statement, 6)
 
 /* Used to represent an expression statement.  Use `EXPR_STMT_EXPR' to
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 8398223311194837441107cb335d497ff5f5ec1c..50b0f20817a168b5e9ac58db59ad44233f079e11 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -5377,6 +5377,7 @@ get_vec_init_expr (tree t)
 #define RANGE_FOR_UNROLL(NODE)	TREE_OPERAND (RANGE_FOR_STMT_CHECK (NODE), 4)
 #define RANGE_FOR_INIT_STMT(NODE) TREE_OPERAND (RANGE_FOR_STMT_CHECK (NODE), 5)
 #define RANGE_FOR_IVDEP(NODE)	TREE_LANG_FLAG_6 (RANGE_FOR_STMT_CHECK (NODE))
+#define RANGE_FOR_NOVECTOR(NODE) TREE_LANG_FLAG_7 (RANGE_FOR_STMT_CHECK (NODE))
 
 /* STMT_EXPR accessor.  */
 #define STMT_EXPR_STMT(NODE)	TREE_OPERAND (STMT_EXPR_CHECK (NODE), 0)
@@ -7286,7 +7287,7 @@ extern bool maybe_clone_body			(tree);
 
 /* In parser.cc */
 extern tree cp_convert_range_for (tree, tree, tree, tree, unsigned int, bool,
-				  unsigned short);
+				  unsigned short, bool);
 extern void cp_convert_omp_range_for (tree &, vec<tree, va_gc> *, tree &,
 				      tree &, tree &, tree &, tree &, tree &);
 extern void cp_finish_omp_range_for (tree, tree);
@@ -7609,16 +7610,19 @@ extern void begin_else_clause			(tree);
 extern void finish_else_clause			(tree);
 extern void finish_if_stmt			(tree);
 extern tree begin_while_stmt			(void);
-extern void finish_while_stmt_cond	(tree, tree, bool, unsigned short);
+extern void finish_while_stmt_cond	(tree, tree, bool, unsigned short,
+					 bool);
 extern void finish_while_stmt			(tree);
 extern tree begin_do_stmt			(void);
 extern void finish_do_body			(tree);
-extern void finish_do_stmt		(tree, tree, bool, unsigned short);
+extern void finish_do_stmt		(tree, tree, bool, unsigned short,
+					 bool);
 extern tree finish_return_stmt			(tree);
 extern tree begin_for_scope			(tree *);
 extern tree begin_for_stmt			(tree, tree);
 extern void finish_init_stmt			(tree);
-extern void finish_for_cond		(tree, tree, bool, unsigned short);
+extern void finish_for_cond		(tree, tree, bool, unsigned short,
+					 bool);
 extern void finish_for_expr			(tree, tree);
 extern void finish_for_stmt			(tree);
 extern tree begin_range_for_stmt		(tree, tree);
diff --git a/gcc/cp/init.cc b/gcc/cp/init.cc
index af6e30f511e142c7a594e742d128b2bf0aa8fb8d..5b735b27e6f5bc6b439ae64665902f4f1ca76f95 100644
--- a/gcc/cp/init.cc
+++ b/gcc/cp/init.cc
@@ -4846,7 +4846,7 @@ build_vec_init (tree base, tree maxindex, tree init,
       finish_init_stmt (for_stmt);
       finish_for_cond (build2 (GT_EXPR, boolean_type_node, iterator,
 			       build_int_cst (TREE_TYPE (iterator), -1)),
-		       for_stmt, false, 0);
+		       for_stmt, false, 0, false);
       /* We used to pass this decrement to finish_for_expr; now we add it to
 	 elt_init below so it's part of the same full-expression as the
 	 initialization, and thus happens before any potentially throwing
diff --git a/gcc/cp/method.cc b/gcc/cp/method.cc
index 91cf943f11089c0e6bcbe8377daa4e016f956d56..fce49c796199c2c65cd70684e2942fea1b6b2ebd 100644
--- a/gcc/cp/method.cc
+++ b/gcc/cp/method.cc
@@ -1645,7 +1645,8 @@ build_comparison_op (tree fndecl, bool defining, tsubst_flags_t complain)
 		      add_stmt (idx);
 		      finish_init_stmt (for_stmt);
 		      finish_for_cond (build2 (LE_EXPR, boolean_type_node, idx,
-					       maxval), for_stmt, false, 0);
+					       maxval), for_stmt, false, 0,
+					       false);
 		      finish_for_expr (cp_build_unary_op (PREINCREMENT_EXPR,
 							  TARGET_EXPR_SLOT (idx),
 							  false, complain),
diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index dd3665c8ccf48a8a0b1ba2c06400fe50999ea240..0bc110121d51ee13258b7ff0e4ad7851b4eae78e 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -2324,15 +2324,15 @@ static tree cp_parser_selection_statement
 static tree cp_parser_condition
   (cp_parser *);
 static tree cp_parser_iteration_statement
-  (cp_parser *, bool *, bool, unsigned short);
+  (cp_parser *, bool *, bool, unsigned short, bool);
 static bool cp_parser_init_statement
   (cp_parser *, tree *decl);
 static tree cp_parser_for
-  (cp_parser *, bool, unsigned short);
+  (cp_parser *, bool, unsigned short, bool);
 static tree cp_parser_c_for
-  (cp_parser *, tree, tree, bool, unsigned short);
+  (cp_parser *, tree, tree, bool, unsigned short, bool);
 static tree cp_parser_range_for
-  (cp_parser *, tree, tree, tree, bool, unsigned short, bool);
+  (cp_parser *, tree, tree, tree, bool, unsigned short, bool, bool);
 static void do_range_for_auto_deduction
   (tree, tree, tree, unsigned int);
 static tree cp_parser_perform_range_for_lookup
@@ -12414,7 +12414,8 @@ cp_parser_statement (cp_parser* parser, tree in_statement_expr,
 	case RID_DO:
 	case RID_FOR:
 	  std_attrs = process_stmt_hotness_attribute (std_attrs, attrs_loc);
-	  statement = cp_parser_iteration_statement (parser, if_p, false, 0);
+	  statement = cp_parser_iteration_statement (parser, if_p, false, 0,
+						     false);
 	  break;
 
 	case RID_BREAK:
@@ -13594,7 +13595,8 @@ cp_parser_condition (cp_parser* parser)
    not included. */
 
 static tree
-cp_parser_for (cp_parser *parser, bool ivdep, unsigned short unroll)
+cp_parser_for (cp_parser *parser, bool ivdep, unsigned short unroll,
+	       bool novector)
 {
   tree init, scope, decl;
   bool is_range_for;
@@ -13624,14 +13626,14 @@ cp_parser_for (cp_parser *parser, bool ivdep, unsigned short unroll)
 
   if (is_range_for)
     return cp_parser_range_for (parser, scope, init, decl, ivdep, unroll,
-				false);
+				novector, false);
   else
-    return cp_parser_c_for (parser, scope, init, ivdep, unroll);
+    return cp_parser_c_for (parser, scope, init, ivdep, unroll, novector);
 }
 
 static tree
 cp_parser_c_for (cp_parser *parser, tree scope, tree init, bool ivdep,
-		 unsigned short unroll)
+		 unsigned short unroll, bool novector)
 {
   /* Normal for loop */
   tree condition = NULL_TREE;
@@ -13658,7 +13660,13 @@ cp_parser_c_for (cp_parser *parser, tree scope, tree init, bool ivdep,
 		       "%<GCC unroll%> pragma");
       condition = error_mark_node;
     }
-  finish_for_cond (condition, stmt, ivdep, unroll);
+  else if (novector)
+    {
+      cp_parser_error (parser, "missing loop condition in loop with "
+		       "%<GCC novector%> pragma");
+      condition = error_mark_node;
+    }
+  finish_for_cond (condition, stmt, ivdep, unroll, novector);
   /* Look for the `;'.  */
   cp_parser_require (parser, CPP_SEMICOLON, RT_SEMICOLON);
 
@@ -13682,7 +13690,8 @@ cp_parser_c_for (cp_parser *parser, tree scope, tree init, bool ivdep,
 
 static tree
 cp_parser_range_for (cp_parser *parser, tree scope, tree init, tree range_decl,
-		     bool ivdep, unsigned short unroll, bool is_omp)
+		     bool ivdep, unsigned short unroll, bool novector,
+		     bool is_omp)
 {
   tree stmt, range_expr;
   auto_vec <cxx_binding *, 16> bindings;
@@ -13758,6 +13767,8 @@ cp_parser_range_for (cp_parser *parser, tree scope, tree init, tree range_decl,
 	RANGE_FOR_IVDEP (stmt) = 1;
       if (unroll)
 	RANGE_FOR_UNROLL (stmt) = build_int_cst (integer_type_node, unroll);
+      if (novector)
+	RANGE_FOR_NOVECTOR (stmt) = 1;
       finish_range_for_decl (stmt, range_decl, range_expr);
       if (!type_dependent_expression_p (range_expr)
 	  /* do_auto_deduction doesn't mess with template init-lists.  */
@@ -13770,7 +13781,7 @@ cp_parser_range_for (cp_parser *parser, tree scope, tree init, tree range_decl,
       stmt = begin_for_stmt (scope, init);
       stmt = cp_convert_range_for (stmt, range_decl, range_expr,
 				   decomp_first_name, decomp_cnt, ivdep,
-				   unroll);
+				   unroll, novector);
     }
   return stmt;
 }
@@ -13948,7 +13959,7 @@ warn_for_range_copy (tree decl, tree expr)
 tree
 cp_convert_range_for (tree statement, tree range_decl, tree range_expr,
 		      tree decomp_first_name, unsigned int decomp_cnt,
-		      bool ivdep, unsigned short unroll)
+		      bool ivdep, unsigned short unroll, bool novector)
 {
   tree begin, end;
   tree iter_type, begin_expr, end_expr;
@@ -14008,7 +14019,7 @@ cp_convert_range_for (tree statement, tree range_decl, tree range_expr,
 				 begin, ERROR_MARK,
 				 end, ERROR_MARK,
 				 NULL_TREE, NULL, tf_warning_or_error);
-  finish_for_cond (condition, statement, ivdep, unroll);
+  finish_for_cond (condition, statement, ivdep, unroll, novector);
 
   /* The new increment expression.  */
   expression = finish_unary_op_expr (input_location,
@@ -14175,7 +14186,7 @@ cp_parser_range_for_member_function (tree range, tree identifier)
 
 static tree
 cp_parser_iteration_statement (cp_parser* parser, bool *if_p, bool ivdep,
-			       unsigned short unroll)
+			       unsigned short unroll, bool novector)
 {
   cp_token *token;
   enum rid keyword;
@@ -14209,7 +14220,7 @@ cp_parser_iteration_statement (cp_parser* parser, bool *if_p, bool ivdep,
 	parens.require_open (parser);
 	/* Parse the condition.  */
 	condition = cp_parser_condition (parser);
-	finish_while_stmt_cond (condition, statement, ivdep, unroll);
+	finish_while_stmt_cond (condition, statement, ivdep, unroll, novector);
 	/* Look for the `)'.  */
 	parens.require_close (parser);
 	/* Parse the dependent statement.  */
@@ -14244,7 +14255,7 @@ cp_parser_iteration_statement (cp_parser* parser, bool *if_p, bool ivdep,
 	/* Parse the expression.  */
 	expression = cp_parser_expression (parser);
 	/* We're done with the do-statement.  */
-	finish_do_stmt (expression, statement, ivdep, unroll);
+	finish_do_stmt (expression, statement, ivdep, unroll, novector);
 	/* Look for the `)'.  */
 	parens.require_close (parser);
 	/* Look for the `;'.  */
@@ -14258,7 +14269,7 @@ cp_parser_iteration_statement (cp_parser* parser, bool *if_p, bool ivdep,
 	matching_parens parens;
 	parens.require_open (parser);
 
-	statement = cp_parser_for (parser, ivdep, unroll);
+	statement = cp_parser_for (parser, ivdep, unroll, novector);
 
 	/* Look for the `)'.  */
 	parens.require_close (parser);
@@ -43815,7 +43826,7 @@ cp_parser_omp_for_loop (cp_parser *parser, enum tree_code code, tree clauses,
 	      cp_parser_require (parser, CPP_COLON, RT_COLON);
 
 	      init = cp_parser_range_for (parser, NULL_TREE, NULL_TREE, decl,
-					  false, 0, true);
+					  false, 0, true, false);
 
 	      cp_convert_omp_range_for (this_pre_body, for_block, decl,
 					orig_decl, init, orig_init,
@@ -49300,6 +49311,15 @@ cp_parser_pragma_unroll (cp_parser *parser, cp_token *pragma_tok)
   return unroll;
 }
 
+/* Parse a pragma GCC novector.  */
+
+static bool
+cp_parser_pragma_novector (cp_parser *parser, cp_token *pragma_tok)
+{
+  cp_parser_skip_to_pragma_eol (parser, pragma_tok);
+  return true;
+}
+
 /* Normal parsing of a pragma token.  Here we can (and must) use the
    regular lexer.  */
 
@@ -49613,17 +49633,33 @@ cp_parser_pragma (cp_parser *parser, enum pragma_context context, bool *if_p)
 	    break;
 	  }
 	const bool ivdep = cp_parser_pragma_ivdep (parser, pragma_tok);
-	unsigned short unroll;
+	unsigned short unroll = 0;
+	bool novector = false;
 	cp_token *tok = cp_lexer_peek_token (the_parser->lexer);
-	if (tok->type == CPP_PRAGMA
-	    && cp_parser_pragma_kind (tok) == PRAGMA_UNROLL)
+
+	while (tok->type == CPP_PRAGMA)
 	  {
-	    tok = cp_lexer_consume_token (parser->lexer);
-	    unroll = cp_parser_pragma_unroll (parser, tok);
-	    tok = cp_lexer_peek_token (the_parser->lexer);
+	    switch (cp_parser_pragma_kind (tok))
+	      {
+		case PRAGMA_UNROLL:
+		  {
+		    tok = cp_lexer_consume_token (parser->lexer);
+		    unroll = cp_parser_pragma_unroll (parser, tok);
+		    tok = cp_lexer_peek_token (the_parser->lexer);
+		    break;
+		  }
+		case PRAGMA_NOVECTOR:
+		  {
+		    tok = cp_lexer_consume_token (parser->lexer);
+		    novector = cp_parser_pragma_novector (parser, tok);
+		    tok = cp_lexer_peek_token (the_parser->lexer);
+		    break;
+		  }
+		default:
+		  gcc_unreachable ();
+	      }
 	  }
-	else
-	  unroll = 0;
+
 	if (tok->type != CPP_KEYWORD
 	    || (tok->keyword != RID_FOR
 		&& tok->keyword != RID_WHILE
@@ -49632,7 +49668,7 @@ cp_parser_pragma (cp_parser *parser, enum pragma_context context, bool *if_p)
 	    cp_parser_error (parser, "for, while or do statement expected");
 	    return false;
 	  }
-	cp_parser_iteration_statement (parser, if_p, ivdep, unroll);
+	cp_parser_iteration_statement (parser, if_p, ivdep, unroll, novector);
 	return true;
       }
 
@@ -49646,17 +49682,82 @@ cp_parser_pragma (cp_parser *parser, enum pragma_context context, bool *if_p)
 	  }
 	const unsigned short unroll
 	  = cp_parser_pragma_unroll (parser, pragma_tok);
-	bool ivdep;
+	bool ivdep = false;
+	bool novector = false;
 	cp_token *tok = cp_lexer_peek_token (the_parser->lexer);
-	if (tok->type == CPP_PRAGMA
-	    && cp_parser_pragma_kind (tok) == PRAGMA_IVDEP)
+
+	while (tok->type == CPP_PRAGMA)
 	  {
-	    tok = cp_lexer_consume_token (parser->lexer);
-	    ivdep = cp_parser_pragma_ivdep (parser, tok);
-	    tok = cp_lexer_peek_token (the_parser->lexer);
+	    switch (cp_parser_pragma_kind (tok))
+	      {
+		case PRAGMA_IVDEP:
+		  {
+		    tok = cp_lexer_consume_token (parser->lexer);
+		    ivdep = cp_parser_pragma_ivdep (parser, tok);
+		    tok = cp_lexer_peek_token (the_parser->lexer);
+		    break;
+		  }
+		case PRAGMA_NOVECTOR:
+		  {
+		    tok = cp_lexer_consume_token (parser->lexer);
+		    novector = cp_parser_pragma_novector (parser, tok);
+		    tok = cp_lexer_peek_token (the_parser->lexer);
+		    break;
+		  }
+		default:
+		  gcc_unreachable ();
+	      }
 	  }
-	else
-	  ivdep = false;
+
+	if (tok->type != CPP_KEYWORD
+	    || (tok->keyword != RID_FOR
+		&& tok->keyword != RID_WHILE
+		&& tok->keyword != RID_DO))
+	  {
+	    cp_parser_error (parser, "for, while or do statement expected");
+	    return false;
+	  }
+	cp_parser_iteration_statement (parser, if_p, ivdep, unroll, novector);
+	return true;
+      }
+
+    case PRAGMA_NOVECTOR:
+      {
+	if (context == pragma_external)
+	  {
+	    error_at (pragma_tok->location,
+		      "%<#pragma GCC novector%> must be inside a function");
+	    break;
+	  }
+	const bool novector
+	  = cp_parser_pragma_novector (parser, pragma_tok);
+	bool ivdep = false;
+	unsigned short unroll;
+	cp_token *tok = cp_lexer_peek_token (the_parser->lexer);
+
+	while (tok->type == CPP_PRAGMA)
+	  {
+	    switch (cp_parser_pragma_kind (tok))
+	      {
+		case PRAGMA_IVDEP:
+		  {
+		    tok = cp_lexer_consume_token (parser->lexer);
+		    ivdep = cp_parser_pragma_ivdep (parser, tok);
+		    tok = cp_lexer_peek_token (the_parser->lexer);
+		    break;
+		  }
+		case PRAGMA_UNROLL:
+		  {
+		    tok = cp_lexer_consume_token (parser->lexer);
+		    unroll = cp_parser_pragma_unroll (parser, tok);
+		    tok = cp_lexer_peek_token (the_parser->lexer);
+		    break;
+		  }
+		default:
+		  gcc_unreachable ();
+	      }
+	  }
+
 	if (tok->type != CPP_KEYWORD
 	    || (tok->keyword != RID_FOR
 		&& tok->keyword != RID_WHILE
@@ -49665,7 +49766,7 @@ cp_parser_pragma (cp_parser *parser, enum pragma_context context, bool *if_p)
 	    cp_parser_error (parser, "for, while or do statement expected");
 	    return false;
 	  }
-	cp_parser_iteration_statement (parser, if_p, ivdep, unroll);
+	cp_parser_iteration_statement (parser, if_p, ivdep, unroll, novector);
 	return true;
       }
 
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 2345a18becc1160b9d12f3d88cccb66c8917373c..7b0d01a90e3c4012ec603ebe04cbbb31a7dd1570 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -19036,7 +19036,7 @@ tsubst_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl)
       RECUR (FOR_INIT_STMT (t));
       finish_init_stmt (stmt);
       tmp = RECUR (FOR_COND (t));
-      finish_for_cond (tmp, stmt, false, 0);
+      finish_for_cond (tmp, stmt, false, 0, false);
       tmp = RECUR (FOR_EXPR (t));
       finish_for_expr (tmp, stmt);
       {
@@ -19073,6 +19073,7 @@ tsubst_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl)
 	  {
 	    RANGE_FOR_IVDEP (stmt) = RANGE_FOR_IVDEP (t);
 	    RANGE_FOR_UNROLL (stmt) = RANGE_FOR_UNROLL (t);
+	    RANGE_FOR_NOVECTOR (stmt) = RANGE_FOR_NOVECTOR (t);
 	    finish_range_for_decl (stmt, decl, expr);
 	    if (decomp_first && decl != error_mark_node)
 	      cp_finish_decomp (decl, decomp_first, decomp_cnt);
@@ -19083,7 +19084,8 @@ tsubst_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl)
 				     ? tree_to_uhwi (RANGE_FOR_UNROLL (t)) : 0);
 	    stmt = cp_convert_range_for (stmt, decl, expr,
 					 decomp_first, decomp_cnt,
-					 RANGE_FOR_IVDEP (t), unroll);
+					 RANGE_FOR_IVDEP (t), unroll,
+					 RANGE_FOR_NOVECTOR (t));
 	  }
 
 	bool prev = note_iteration_stmt_body_start ();
@@ -19096,7 +19098,7 @@ tsubst_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl)
     case WHILE_STMT:
       stmt = begin_while_stmt ();
       tmp = RECUR (WHILE_COND (t));
-      finish_while_stmt_cond (tmp, stmt, false, 0);
+      finish_while_stmt_cond (tmp, stmt, false, 0, false);
       {
 	bool prev = note_iteration_stmt_body_start ();
 	RECUR (WHILE_BODY (t));
@@ -19114,7 +19116,7 @@ tsubst_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl)
       }
       finish_do_body (stmt);
       tmp = RECUR (DO_COND (t));
-      finish_do_stmt (tmp, stmt, false, 0);
+      finish_do_stmt (tmp, stmt, false, 0, false);
       break;
 
     case IF_STMT:
diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index 8fb47fd179eb2af2e82bf31d188023e9b9d41de9..b79975109c22ebcfcb060b4f20f32f69f3c3c444 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -1148,7 +1148,7 @@ begin_while_stmt (void)
 
 void
 finish_while_stmt_cond (tree cond, tree while_stmt, bool ivdep,
-			unsigned short unroll)
+			unsigned short unroll, bool novector)
 {
   cond = maybe_convert_cond (cond);
   finish_cond (&WHILE_COND (while_stmt), cond);
@@ -1168,6 +1168,13 @@ finish_while_stmt_cond (tree cond, tree while_stmt, bool ivdep,
 						     annot_expr_unroll_kind),
 				      build_int_cst (integer_type_node,
 						     unroll));
+  if (novector && cond != error_mark_node)
+    WHILE_COND (while_stmt) = build3 (ANNOTATE_EXPR,
+				      TREE_TYPE (WHILE_COND (while_stmt)),
+				      WHILE_COND (while_stmt),
+				      build_int_cst (integer_type_node,
+						     annot_expr_no_vector_kind),
+				      integer_zero_node);
   simplify_loop_decl_cond (&WHILE_COND (while_stmt), WHILE_BODY (while_stmt));
 }
 
@@ -1212,7 +1219,8 @@ finish_do_body (tree do_stmt)
    COND is as indicated.  */
 
 void
-finish_do_stmt (tree cond, tree do_stmt, bool ivdep, unsigned short unroll)
+finish_do_stmt (tree cond, tree do_stmt, bool ivdep, unsigned short unroll,
+		bool novector)
 {
   cond = maybe_convert_cond (cond);
   end_maybe_infinite_loop (cond);
@@ -1229,6 +1237,10 @@ finish_do_stmt (tree cond, tree do_stmt, bool ivdep, unsigned short unroll)
     cond = build3 (ANNOTATE_EXPR, TREE_TYPE (cond), cond,
 		   build_int_cst (integer_type_node, annot_expr_unroll_kind),
 		   build_int_cst (integer_type_node, unroll));
+  if (novector && cond != error_mark_node)
+    cond = build3 (ANNOTATE_EXPR, TREE_TYPE (cond), cond,
+		   build_int_cst (integer_type_node, annot_expr_no_vector_kind),
+		   integer_zero_node);
   DO_COND (do_stmt) = cond;
 }
 
@@ -1325,7 +1337,7 @@ finish_init_stmt (tree for_stmt)
    FOR_STMT.  */
 
 void
-finish_for_cond (tree cond, tree for_stmt, bool ivdep, unsigned short unroll)
+finish_for_cond (tree cond, tree for_stmt, bool ivdep, unsigned short unroll, bool novector)
 {
   cond = maybe_convert_cond (cond);
   finish_cond (&FOR_COND (for_stmt), cond);
@@ -1345,6 +1357,13 @@ finish_for_cond (tree cond, tree for_stmt, bool ivdep, unsigned short unroll)
 						 annot_expr_unroll_kind),
 				  build_int_cst (integer_type_node,
 						 unroll));
+  if (novector && cond != error_mark_node)
+    FOR_COND (for_stmt) = build3 (ANNOTATE_EXPR,
+				  TREE_TYPE (FOR_COND (for_stmt)),
+				  FOR_COND (for_stmt),
+				  build_int_cst (integer_type_node,
+						 annot_expr_no_vector_kind),
+				  integer_zero_node);
   simplify_loop_decl_cond (&FOR_COND (for_stmt), FOR_BODY (for_stmt));
 }
 
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 3040a9bdea65d27f8d20572b4ed37375f5fe949b..baac6643d1abbf33d592e68aca49ac83e3c29188 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -24349,6 +24349,25 @@ void ignore_vec_dep (int *a, int k, int c, int m)
 @}
 @end smallexample
 
+@cindex pragma GCC novector
+@item #pragma GCC novector
+
+With this pragma, the programmer asserts that the following loop should be
+prevented from executing concurrently with SIMD (single instruction multiple
+data) instructions.
+
+For example, the compiler cannot vectorize the following loop with the pragma:
+
+@smallexample
+void foo (int n, int *a, int *b, int *c)
+@{
+  int i, j;
+#pragma GCC novector
+  for (i = 0; i < n; ++i)
+    a[i] = b[i] + c[i];
+@}
+@end smallexample
+
 @cindex pragma GCC unroll @var{n}
 @item #pragma GCC unroll @var{n}
 
diff --git a/gcc/testsuite/g++.dg/vect/vect-novector-pragma.cc b/gcc/testsuite/g++.dg/vect/vect-novector-pragma.cc
new file mode 100644
index 0000000000000000000000000000000000000000..4667935b641a06e3004904dc86c4513a78736f04
--- /dev/null
+++ b/gcc/testsuite/g++.dg/vect/vect-novector-pragma.cc
@@ -0,0 +1,29 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target vect_int } */
+
+#include <vector>
+
+void f4 (std::vector<int> a, std::vector<int> b, int n)
+{
+    int i = 0;
+#pragma GCC novector
+    while (i < (n & -8))
+      {
+        a[i] += b[i];
+        i++;
+      }
+}
+
+
+void f5 (std::vector<int> a, std::vector<int> b, int n)
+{
+    int i = 0;
+#pragma GCC novector
+    for (auto x : b)
+      {
+        a[i] += x;
+        i++;
+      }
+}
+
+/* { dg-final { scan-tree-dump-not "LOOP VECTORIZED" "vect" } } */
diff --git a/gcc/testsuite/gcc.dg/vect/vect-novector-pragma.c b/gcc/testsuite/gcc.dg/vect/vect-novector-pragma.c
new file mode 100644
index 0000000000000000000000000000000000000000..c4b3957711db8f78d26a32634e9bbfdc11a33302
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-novector-pragma.c
@@ -0,0 +1,34 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target vect_int } */
+
+void f1 (int * restrict a, int * restrict b, int n)
+{
+#pragma GCC novector
+    for (int i = 0; i < (n & -8); i++)
+      a[i] += b[i];
+}
+
+void f2 (int * restrict a, int * restrict b, int n)
+{
+    int i = 0;
+#pragma GCC novector
+    do
+      {
+        a[i] += b[i];
+        i++;
+      }
+    while (i < (n & -8));
+}
+
+void f3 (int * restrict a, int * restrict b, int n)
+{
+    int i = 0;
+#pragma GCC novector
+    while (i < (n & -8))
+      {
+        a[i] += b[i];
+        i++;
+      }
+}
+
+/* { dg-final { scan-tree-dump-not "LOOP VECTORIZED" "vect" } } */
diff --git a/gcc/tree-core.h b/gcc/tree-core.h
index c48a12b378f0b3086747bee43b38e2da3f90b24d..9268a0668390192caac9efaade0a53d9359cf9a7 100644
--- a/gcc/tree-core.h
+++ b/gcc/tree-core.h
@@ -1063,6 +1063,7 @@ struct GTY(()) tree_base {
       unsigned lang_flag_4 : 1;
       unsigned lang_flag_5 : 1;
       unsigned lang_flag_6 : 1;
+      unsigned lang_flag_7 : 1;
       unsigned saturating_flag : 1;
 
       unsigned unsigned_flag : 1;
@@ -1071,7 +1072,7 @@ struct GTY(()) tree_base {
       unsigned nameless_flag : 1;
       unsigned atomic_flag : 1;
       unsigned unavailable_flag : 1;
-      unsigned spare0 : 2;
+      unsigned spare0 : 1;
 
       unsigned spare1 : 8;
 
diff --git a/gcc/tree.h b/gcc/tree.h
index 1854fe4a7d4d25b0cb55ee70402d5721f8b629ba..e96e8884bf68de77d19c95a87ae1c147460c23df 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -1112,6 +1112,8 @@ extern void omp_clause_range_check_failed (const_tree, const char *, int,
   (TREE_NOT_CHECK2 (NODE, TREE_VEC, SSA_NAME)->base.u.bits.lang_flag_5)
 #define TREE_LANG_FLAG_6(NODE) \
   (TREE_NOT_CHECK2 (NODE, TREE_VEC, SSA_NAME)->base.u.bits.lang_flag_6)
+#define TREE_LANG_FLAG_7(NODE) \
+  (TREE_NOT_CHECK2 (NODE, TREE_VEC, SSA_NAME)->base.u.bits.lang_flag_7)
 
 /* Define additional fields and accessors for nodes representing constants.  */

Comments

Jason Merrill June 29, 2023, 10:17 p.m. UTC | #1
On 6/28/23 09:41, Tamar Christina wrote:
> Hi All,
> 
> FORTRAN currently has a pragma NOVECTOR for indicating that vectorization should
> not be applied to a particular loop.
> 
> ICC/ICX also has such a pragma for C and C++ called #pragma novector.
> 
> As part of this patch series I need a way to easily turn off vectorization of
> particular loops, particularly for testsuite reasons.
> 
> This patch proposes a #pragma GCC novector that does the same for C and C++
> as gfortan does for FORTRAN and what ICX/ICX does for C and C++.
> 
> I added only some basic tests here, but the next patch in the series uses this
> in the testsuite in about ~800 tests.
> 
> Bootstrapped Regtested on aarch64-none-linux-gnu and no issues.
> 
> Ok for master?
> 
> Thanks,
> Tamar
> 
> gcc/c-family/ChangeLog:
> 
> 	* c-pragma.h (enum pragma_kind): Add PRAGMA_NOVECTOR.
> 	* c-pragma.cc (init_pragma): Use it.
> 
> gcc/c/ChangeLog:
> 
> 	* c-parser.cc (c_parser_while_statement, c_parser_do_statement,
> 	c_parser_for_statement, c_parser_statement_after_labels,
> 	c_parse_pragma_novector, c_parser_pragma): Wire through novector and
> 	default to false.

I'll let the C maintainers review the C changes.

> gcc/cp/ChangeLog:
> 
> 	* cp-tree.def (RANGE_FOR_STMT): Update comment.
> 	* cp-tree.h (RANGE_FOR_NOVECTOR): New.
> 	(cp_convert_range_for, finish_while_stmt_cond, finish_do_stmt,
> 	finish_for_cond): Add novector param.
> 	* init.cc (build_vec_init): Default novector to false.
> 	* method.cc (build_comparison_op): Likewise.
> 	* parser.cc (cp_parser_statement): Likewise.
> 	(cp_parser_for, cp_parser_c_for, cp_parser_range_for,
> 	cp_convert_range_for, cp_parser_iteration_statement,
> 	cp_parser_omp_for_loop, cp_parser_pragma): Support novector.
> 	(cp_parser_pragma_novector): New.
> 	* pt.cc (tsubst_expr): Likewise.
> 	* semantics.cc (finish_while_stmt_cond, finish_do_stmt,
> 	finish_for_cond): Likewise.
> 
> gcc/ChangeLog:
> 
> 	* doc/extend.texi: Document it.
> 	* tree-core.h (struct tree_base): Add lang_flag_7 and reduce spare0.
> 	* tree.h (TREE_LANG_FLAG_7): New.

This doesn't seem necessary; I think only flags 1 and 6 are currently 
used in RANGE_FOR_STMT.

> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/vect/vect-novector-pragma.cc: New test.
> 	* gcc.dg/vect/vect-novector-pragma.c: New test.
> 
> --- inline copy of patch --
>...
> @@ -13594,7 +13595,8 @@ cp_parser_condition (cp_parser* parser)
>      not included. */
>   
>   static tree
> -cp_parser_for (cp_parser *parser, bool ivdep, unsigned short unroll)
> +cp_parser_for (cp_parser *parser, bool ivdep, unsigned short unroll,
> +	       bool novector)

I wonder about combining the ivdep and novector parameters here and in 
other functions?  Up to you.

> @@ -49613,17 +49633,33 @@ cp_parser_pragma (cp_parser *parser, enum pragma_context context, bool *if_p)
>   	    break;
>   	  }
>   	const bool ivdep = cp_parser_pragma_ivdep (parser, pragma_tok);
> -	unsigned short unroll;
> +	unsigned short unroll = 0;
> +	bool novector = false;
>   	cp_token *tok = cp_lexer_peek_token (the_parser->lexer);
> -	if (tok->type == CPP_PRAGMA
> -	    && cp_parser_pragma_kind (tok) == PRAGMA_UNROLL)
> +
> +	while (tok->type == CPP_PRAGMA)
>   	  {
> -	    tok = cp_lexer_consume_token (parser->lexer);
> -	    unroll = cp_parser_pragma_unroll (parser, tok);
> -	    tok = cp_lexer_peek_token (the_parser->lexer);
> +	    switch (cp_parser_pragma_kind (tok))
> +	      {
> +		case PRAGMA_UNROLL:
> +		  {
> +		    tok = cp_lexer_consume_token (parser->lexer);
> +		    unroll = cp_parser_pragma_unroll (parser, tok);
> +		    tok = cp_lexer_peek_token (the_parser->lexer);
> +		    break;
> +		  }
> +		case PRAGMA_NOVECTOR:
> +		  {
> +		    tok = cp_lexer_consume_token (parser->lexer);
> +		    novector = cp_parser_pragma_novector (parser, tok);
> +		    tok = cp_lexer_peek_token (the_parser->lexer);
> +		    break;
> +		  }
> +		default:
> +		  gcc_unreachable ();
> +	      }
>   	  }

Repeating this pattern three times for the three related pragmas is too 
much; please combine the three cases into one.

Jason
Tamar Christina June 30, 2023, 4:18 p.m. UTC | #2
Hi Jason,

Thanks for the review. I only now realized I should have split them between C and C++.

Will do so on the respins.

> 
> On 6/28/23 09:41, Tamar Christina wrote:
> > Hi All,
> >
> > FORTRAN currently has a pragma NOVECTOR for indicating that
> > vectorization should not be applied to a particular loop.
> >
> > ICC/ICX also has such a pragma for C and C++ called #pragma novector.
> >
> > As part of this patch series I need a way to easily turn off
> > vectorization of particular loops, particularly for testsuite reasons.
> >
> > This patch proposes a #pragma GCC novector that does the same for C
> > and C++ as gfortan does for FORTRAN and what ICX/ICX does for C and C++.
> >
> > I added only some basic tests here, but the next patch in the series
> > uses this in the testsuite in about ~800 tests.
> >
> > Bootstrapped Regtested on aarch64-none-linux-gnu and no issues.
> >
> > Ok for master?
> >
> > Thanks,
> > Tamar
> >
> > gcc/c-family/ChangeLog:
> >
> > 	* c-pragma.h (enum pragma_kind): Add PRAGMA_NOVECTOR.
> > 	* c-pragma.cc (init_pragma): Use it.
> >
> > gcc/c/ChangeLog:
> >
> > 	* c-parser.cc (c_parser_while_statement, c_parser_do_statement,
> > 	c_parser_for_statement, c_parser_statement_after_labels,
> > 	c_parse_pragma_novector, c_parser_pragma): Wire through novector
> and
> > 	default to false.
> 
> I'll let the C maintainers review the C changes.
> 
> > gcc/cp/ChangeLog:
> >
> > 	* cp-tree.def (RANGE_FOR_STMT): Update comment.
> > 	* cp-tree.h (RANGE_FOR_NOVECTOR): New.
> > 	(cp_convert_range_for, finish_while_stmt_cond, finish_do_stmt,
> > 	finish_for_cond): Add novector param.
> > 	* init.cc (build_vec_init): Default novector to false.
> > 	* method.cc (build_comparison_op): Likewise.
> > 	* parser.cc (cp_parser_statement): Likewise.
> > 	(cp_parser_for, cp_parser_c_for, cp_parser_range_for,
> > 	cp_convert_range_for, cp_parser_iteration_statement,
> > 	cp_parser_omp_for_loop, cp_parser_pragma): Support novector.
> > 	(cp_parser_pragma_novector): New.
> > 	* pt.cc (tsubst_expr): Likewise.
> > 	* semantics.cc (finish_while_stmt_cond, finish_do_stmt,
> > 	finish_for_cond): Likewise.
> >
> > gcc/ChangeLog:
> >
> > 	* doc/extend.texi: Document it.
> > 	* tree-core.h (struct tree_base): Add lang_flag_7 and reduce spare0.
> > 	* tree.h (TREE_LANG_FLAG_7): New.
> 
> This doesn't seem necessary; I think only flags 1 and 6 are currently used in
> RANGE_FOR_STMT.

Ah fair, I thought every option needed to occupy a specific bit. I'll try to re-use one.

> 
> > gcc/testsuite/ChangeLog:
> >
> > 	* g++.dg/vect/vect-novector-pragma.cc: New test.
> > 	* gcc.dg/vect/vect-novector-pragma.c: New test.
> >
> > --- inline copy of patch --
> >...
> > @@ -13594,7 +13595,8 @@ cp_parser_condition (cp_parser* parser)
> >      not included. */
> >
> >   static tree
> > -cp_parser_for (cp_parser *parser, bool ivdep, unsigned short unroll)
> > +cp_parser_for (cp_parser *parser, bool ivdep, unsigned short unroll,
> > +	       bool novector)
> 
> I wonder about combining the ivdep and novector parameters here and in
> other functions?  Up to you.

As in, combine them in e.g. a struct?

> 
> > @@ -49613,17 +49633,33 @@ cp_parser_pragma (cp_parser *parser,
> enum pragma_context context, bool *if_p)
> >   	    break;
> >   	  }
> >   	const bool ivdep = cp_parser_pragma_ivdep (parser, pragma_tok);
> > -	unsigned short unroll;
> > +	unsigned short unroll = 0;
> > +	bool novector = false;
> >   	cp_token *tok = cp_lexer_peek_token (the_parser->lexer);
> > -	if (tok->type == CPP_PRAGMA
> > -	    && cp_parser_pragma_kind (tok) == PRAGMA_UNROLL)
> > +
> > +	while (tok->type == CPP_PRAGMA)
> >   	  {
> > -	    tok = cp_lexer_consume_token (parser->lexer);
> > -	    unroll = cp_parser_pragma_unroll (parser, tok);
> > -	    tok = cp_lexer_peek_token (the_parser->lexer);
> > +	    switch (cp_parser_pragma_kind (tok))
> > +	      {
> > +		case PRAGMA_UNROLL:
> > +		  {
> > +		    tok = cp_lexer_consume_token (parser->lexer);
> > +		    unroll = cp_parser_pragma_unroll (parser, tok);
> > +		    tok = cp_lexer_peek_token (the_parser->lexer);
> > +		    break;
> > +		  }
> > +		case PRAGMA_NOVECTOR:
> > +		  {
> > +		    tok = cp_lexer_consume_token (parser->lexer);
> > +		    novector = cp_parser_pragma_novector (parser, tok);
> > +		    tok = cp_lexer_peek_token (the_parser->lexer);
> > +		    break;
> > +		  }
> > +		default:
> > +		  gcc_unreachable ();
> > +	      }
> >   	  }
> 
> Repeating this pattern three times for the three related pragmas is too much;
> please combine the three cases into one.

Sure, I had some trouble combing them before because of the initial token being
consumed, but think I know a way.

Thanks for the review, will send updated split patch Monday.

Cheers,
Tamar
> 
> Jason
Jason Merrill June 30, 2023, 4:44 p.m. UTC | #3
On Fri, Jun 30, 2023, 12:18 PM Tamar Christina <Tamar.Christina@arm.com>
wrote:

> Hi Jason,
>
> Thanks for the review. I only now realized I should have split them
> between C and C++.
>
> Will do so on the respins.
>
> >
> > On 6/28/23 09:41, Tamar Christina wrote:
> > > Hi All,
> > >
> > > FORTRAN currently has a pragma NOVECTOR for indicating that
> > > vectorization should not be applied to a particular loop.
> > >
> > > ICC/ICX also has such a pragma for C and C++ called #pragma novector.
> > >
> > > As part of this patch series I need a way to easily turn off
> > > vectorization of particular loops, particularly for testsuite reasons.
> > >
> > > This patch proposes a #pragma GCC novector that does the same for C
> > > and C++ as gfortan does for FORTRAN and what ICX/ICX does for C and
> C++.
> > >
> > > I added only some basic tests here, but the next patch in the series
> > > uses this in the testsuite in about ~800 tests.
> > >
> > > Bootstrapped Regtested on aarch64-none-linux-gnu and no issues.
> > >
> > > Ok for master?
> > >
> > > Thanks,
> > > Tamar
> > >
> > > gcc/c-family/ChangeLog:
> > >
> > >     * c-pragma.h (enum pragma_kind): Add PRAGMA_NOVECTOR.
> > >     * c-pragma.cc (init_pragma): Use it.
> > >
> > > gcc/c/ChangeLog:
> > >
> > >     * c-parser.cc (c_parser_while_statement, c_parser_do_statement,
> > >     c_parser_for_statement, c_parser_statement_after_labels,
> > >     c_parse_pragma_novector, c_parser_pragma): Wire through novector
> > and
> > >     default to false.
> >
> > I'll let the C maintainers review the C changes.
> >
> > > gcc/cp/ChangeLog:
> > >
> > >     * cp-tree.def (RANGE_FOR_STMT): Update comment.
> > >     * cp-tree.h (RANGE_FOR_NOVECTOR): New.
> > >     (cp_convert_range_for, finish_while_stmt_cond, finish_do_stmt,
> > >     finish_for_cond): Add novector param.
> > >     * init.cc (build_vec_init): Default novector to false.
> > >     * method.cc (build_comparison_op): Likewise.
> > >     * parser.cc (cp_parser_statement): Likewise.
> > >     (cp_parser_for, cp_parser_c_for, cp_parser_range_for,
> > >     cp_convert_range_for, cp_parser_iteration_statement,
> > >     cp_parser_omp_for_loop, cp_parser_pragma): Support novector.
> > >     (cp_parser_pragma_novector): New.
> > >     * pt.cc (tsubst_expr): Likewise.
> > >     * semantics.cc (finish_while_stmt_cond, finish_do_stmt,
> > >     finish_for_cond): Likewise.
> > >
> > > gcc/ChangeLog:
> > >
> > >     * doc/extend.texi: Document it.
> > >     * tree-core.h (struct tree_base): Add lang_flag_7 and reduce
> spare0.
> > >     * tree.h (TREE_LANG_FLAG_7): New.
> >
> > This doesn't seem necessary; I think only flags 1 and 6 are currently
> used in
> > RANGE_FOR_STMT.
>
> Ah fair, I thought every option needed to occupy a specific bit. I'll try
> to re-use one.
>
> >
> > > gcc/testsuite/ChangeLog:
> > >
> > >     * g++.dg/vect/vect-novector-pragma.cc: New test.
> > >     * gcc.dg/vect/vect-novector-pragma.c: New test.
> > >
> > > --- inline copy of patch --
> > >...
> > > @@ -13594,7 +13595,8 @@ cp_parser_condition (cp_parser* parser)
> > >      not included. */
> > >
> > >   static tree
> > > -cp_parser_for (cp_parser *parser, bool ivdep, unsigned short unroll)
> > > +cp_parser_for (cp_parser *parser, bool ivdep, unsigned short unroll,
> > > +          bool novector)
> >
> > I wonder about combining the ivdep and novector parameters here and in
> > other functions?  Up to you.
>
> As in, combine them in e.g. a struct?
>

I was thinking in an int or enum.

>
> > > @@ -49613,17 +49633,33 @@ cp_parser_pragma (cp_parser *parser,
> > enum pragma_context context, bool *if_p)
> > >         break;
> > >       }
> > >     const bool ivdep = cp_parser_pragma_ivdep (parser, pragma_tok);
> > > -   unsigned short unroll;
> > > +   unsigned short unroll = 0;
> > > +   bool novector = false;
> > >     cp_token *tok = cp_lexer_peek_token (the_parser->lexer);
> > > -   if (tok->type == CPP_PRAGMA
> > > -       && cp_parser_pragma_kind (tok) == PRAGMA_UNROLL)
> > > +
> > > +   while (tok->type == CPP_PRAGMA)
> > >       {
> > > -       tok = cp_lexer_consume_token (parser->lexer);
> > > -       unroll = cp_parser_pragma_unroll (parser, tok);
> > > -       tok = cp_lexer_peek_token (the_parser->lexer);
> > > +       switch (cp_parser_pragma_kind (tok))
> > > +         {
> > > +           case PRAGMA_UNROLL:
> > > +             {
> > > +               tok = cp_lexer_consume_token (parser->lexer);
> > > +               unroll = cp_parser_pragma_unroll (parser, tok);
> > > +               tok = cp_lexer_peek_token (the_parser->lexer);
> > > +               break;
> > > +             }
> > > +           case PRAGMA_NOVECTOR:
> > > +             {
> > > +               tok = cp_lexer_consume_token (parser->lexer);
> > > +               novector = cp_parser_pragma_novector (parser, tok);
> > > +               tok = cp_lexer_peek_token (the_parser->lexer);
> > > +               break;
> > > +             }
> > > +           default:
> > > +             gcc_unreachable ();
> > > +         }
> > >       }
> >
> > Repeating this pattern three times for the three related pragmas is too
> much;
> > please combine the three cases into one.
>
> Sure, I had some trouble combing them before because of the initial token
> being
> consumed, but think I know a way.
>
> Thanks for the review, will send updated split patch Monday.
>
> Cheers,
> Tamar
> >
> > Jason
>
>
diff mbox series

Patch

--- a/gcc/c-family/c-pragma.h
+++ b/gcc/c-family/c-pragma.h
@@ -87,6 +87,7 @@  enum pragma_kind {
   PRAGMA_GCC_PCH_PREPROCESS,
   PRAGMA_IVDEP,
   PRAGMA_UNROLL,
+  PRAGMA_NOVECTOR,
 
   PRAGMA_FIRST_EXTERNAL
 };
diff --git a/gcc/c-family/c-pragma.cc b/gcc/c-family/c-pragma.cc
index 0d2b333cebbed32423d5dc6fd2a3ac0ce0bf8b94..848a850b8e123ff1c6ae1ec4b7f8ccbd599b1a88 100644
--- a/gcc/c-family/c-pragma.cc
+++ b/gcc/c-family/c-pragma.cc
@@ -1862,6 +1862,10 @@  init_pragma (void)
     cpp_register_deferred_pragma (parse_in, "GCC", "unroll", PRAGMA_UNROLL,
 				  false, false);
 
+  if (!flag_preprocess_only)
+    cpp_register_deferred_pragma (parse_in, "GCC", "novector", PRAGMA_NOVECTOR,
+				  false, false);
+
 #ifdef HANDLE_PRAGMA_PACK_WITH_EXPANSION
   c_register_pragma_with_expansion (0, "pack", handle_pragma_pack);
 #else
diff --git a/gcc/c/c-parser.cc b/gcc/c/c-parser.cc
index 24a6eb6e4596f32c477e3f1c3f98b9792f7bc92c..9d35fe68704c8aca197bcd4805a146c655959621 100644
--- a/gcc/c/c-parser.cc
+++ b/gcc/c/c-parser.cc
@@ -1572,9 +1572,11 @@  static tree c_parser_c99_block_statement (c_parser *, bool *,
 					  location_t * = NULL);
 static void c_parser_if_statement (c_parser *, bool *, vec<tree> *);
 static void c_parser_switch_statement (c_parser *, bool *);
-static void c_parser_while_statement (c_parser *, bool, unsigned short, bool *);
-static void c_parser_do_statement (c_parser *, bool, unsigned short);
-static void c_parser_for_statement (c_parser *, bool, unsigned short, bool *);
+static void c_parser_while_statement (c_parser *, bool, unsigned short, bool,
+				      bool *);
+static void c_parser_do_statement (c_parser *, bool, unsigned short, bool);
+static void c_parser_for_statement (c_parser *, bool, unsigned short, bool,
+				    bool *);
 static tree c_parser_asm_statement (c_parser *);
 static tree c_parser_asm_operands (c_parser *);
 static tree c_parser_asm_goto_operands (c_parser *);
@@ -6644,13 +6646,13 @@  c_parser_statement_after_labels (c_parser *parser, bool *if_p,
 	  c_parser_switch_statement (parser, if_p);
 	  break;
 	case RID_WHILE:
-	  c_parser_while_statement (parser, false, 0, if_p);
+	  c_parser_while_statement (parser, false, 0, false, if_p);
 	  break;
 	case RID_DO:
-	  c_parser_do_statement (parser, false, 0);
+	  c_parser_do_statement (parser, false, 0, false);
 	  break;
 	case RID_FOR:
-	  c_parser_for_statement (parser, false, 0, if_p);
+	  c_parser_for_statement (parser, false, 0, false, if_p);
 	  break;
 	case RID_GOTO:
 	  c_parser_consume_token (parser);
@@ -7146,7 +7148,7 @@  c_parser_switch_statement (c_parser *parser, bool *if_p)
 
 static void
 c_parser_while_statement (c_parser *parser, bool ivdep, unsigned short unroll,
-			  bool *if_p)
+			  bool novector, bool *if_p)
 {
   tree block, cond, body;
   unsigned char save_in_statement;
@@ -7168,6 +7170,11 @@  c_parser_while_statement (c_parser *parser, bool ivdep, unsigned short unroll,
 		   build_int_cst (integer_type_node,
 				  annot_expr_unroll_kind),
 		   build_int_cst (integer_type_node, unroll));
+  if (novector && cond != error_mark_node)
+    cond = build3 (ANNOTATE_EXPR, TREE_TYPE (cond), cond,
+		   build_int_cst (integer_type_node,
+				  annot_expr_no_vector_kind),
+		   integer_zero_node);
   save_in_statement = in_statement;
   in_statement = IN_ITERATION_STMT;
 
@@ -7199,7 +7206,8 @@  c_parser_while_statement (c_parser *parser, bool ivdep, unsigned short unroll,
 */
 
 static void
-c_parser_do_statement (c_parser *parser, bool ivdep, unsigned short unroll)
+c_parser_do_statement (c_parser *parser, bool ivdep, unsigned short unroll,
+		       bool novector)
 {
   tree block, cond, body;
   unsigned char save_in_statement;
@@ -7228,6 +7236,11 @@  c_parser_do_statement (c_parser *parser, bool ivdep, unsigned short unroll)
 		   build_int_cst (integer_type_node,
 				  annot_expr_unroll_kind),
  		   build_int_cst (integer_type_node, unroll));
+  if (novector && cond != error_mark_node)
+    cond = build3 (ANNOTATE_EXPR, TREE_TYPE (cond), cond,
+		   build_int_cst (integer_type_node,
+				  annot_expr_no_vector_kind),
+		   integer_zero_node);
   if (!c_parser_require (parser, CPP_SEMICOLON, "expected %<;%>"))
     c_parser_skip_to_end_of_block_or_statement (parser);
 
@@ -7296,7 +7309,7 @@  c_parser_do_statement (c_parser *parser, bool ivdep, unsigned short unroll)
 
 static void
 c_parser_for_statement (c_parser *parser, bool ivdep, unsigned short unroll,
-			bool *if_p)
+			bool novector, bool *if_p)
 {
   tree block, cond, incr, body;
   unsigned char save_in_statement;
@@ -7430,6 +7443,12 @@  c_parser_for_statement (c_parser *parser, bool ivdep, unsigned short unroll,
 					  "with %<GCC unroll%> pragma");
 		  cond = error_mark_node;
 		}
+	      else if (novector)
+		{
+		  c_parser_error (parser, "missing loop condition in loop "
+					  "with %<GCC novector%> pragma");
+		  cond = error_mark_node;
+		}
 	      else
 		{
 		  c_parser_consume_token (parser);
@@ -7452,6 +7471,11 @@  c_parser_for_statement (c_parser *parser, bool ivdep, unsigned short unroll,
  			   build_int_cst (integer_type_node,
 					  annot_expr_unroll_kind),
 			   build_int_cst (integer_type_node, unroll));
+	  if (novector && cond != error_mark_node)
+	    cond = build3 (ANNOTATE_EXPR, TREE_TYPE (cond), cond,
+			   build_int_cst (integer_type_node,
+					  annot_expr_no_vector_kind),
+			   integer_zero_node);
 	}
       /* Parse the increment expression (the third expression in a
 	 for-statement).  In the case of a foreach-statement, this is
@@ -13037,6 +13061,16 @@  c_parse_pragma_ivdep (c_parser *parser)
   return true;
 }
 
+/* Parse a pragma GCC novector.  */
+
+static bool
+c_parse_pragma_novector (c_parser *parser)
+{
+  c_parser_consume_pragma (parser);
+  c_parser_skip_to_pragma_eol (parser);
+  return true;
+}
+
 /* Parse a pragma GCC unroll.  */
 
 static unsigned short
@@ -13264,11 +13298,12 @@  c_parser_pragma (c_parser *parser, enum pragma_context context, bool *if_p)
     case PRAGMA_IVDEP:
       {
 	const bool ivdep = c_parse_pragma_ivdep (parser);
-	unsigned short unroll;
+	unsigned short unroll = 0;
+	bool novector = false;
 	if (c_parser_peek_token (parser)->pragma_kind == PRAGMA_UNROLL)
 	  unroll = c_parser_pragma_unroll (parser);
-	else
-	  unroll = 0;
+	if (c_parser_peek_token (parser)->pragma_kind == PRAGMA_NOVECTOR)
+	  novector = c_parse_pragma_novector (parser);
 	if (!c_parser_next_token_is_keyword (parser, RID_FOR)
 	    && !c_parser_next_token_is_keyword (parser, RID_WHILE)
 	    && !c_parser_next_token_is_keyword (parser, RID_DO))
@@ -13277,22 +13312,48 @@  c_parser_pragma (c_parser *parser, enum pragma_context context, bool *if_p)
 	    return false;
 	  }
 	if (c_parser_next_token_is_keyword (parser, RID_FOR))
-	  c_parser_for_statement (parser, ivdep, unroll, if_p);
+	  c_parser_for_statement (parser, ivdep, unroll, novector, if_p);
 	else if (c_parser_next_token_is_keyword (parser, RID_WHILE))
-	  c_parser_while_statement (parser, ivdep, unroll, if_p);
+	  c_parser_while_statement (parser, ivdep, unroll, novector, if_p);
 	else
-	  c_parser_do_statement (parser, ivdep, unroll);
+	  c_parser_do_statement (parser, ivdep, unroll, novector);
       }
       return true;
 
     case PRAGMA_UNROLL:
       {
 	unsigned short unroll = c_parser_pragma_unroll (parser);
-	bool ivdep;
+	bool ivdep = false;
+	bool novector = false;
 	if (c_parser_peek_token (parser)->pragma_kind == PRAGMA_IVDEP)
 	  ivdep = c_parse_pragma_ivdep (parser);
+	if (c_parser_peek_token (parser)->pragma_kind == PRAGMA_NOVECTOR)
+	  novector = c_parse_pragma_novector (parser);
+	if (!c_parser_next_token_is_keyword (parser, RID_FOR)
+	    && !c_parser_next_token_is_keyword (parser, RID_WHILE)
+	    && !c_parser_next_token_is_keyword (parser, RID_DO))
+	  {
+	    c_parser_error (parser, "for, while or do statement expected");
+	    return false;
+	  }
+	if (c_parser_next_token_is_keyword (parser, RID_FOR))
+	  c_parser_for_statement (parser, ivdep, unroll, novector, if_p);
+	else if (c_parser_next_token_is_keyword (parser, RID_WHILE))
+	  c_parser_while_statement (parser, ivdep, unroll, novector, if_p);
 	else
-	  ivdep = false;
+	  c_parser_do_statement (parser, ivdep, unroll, novector);
+      }
+      return true;
+
+    case PRAGMA_NOVECTOR:
+      {
+	bool novector = c_parse_pragma_novector (parser);
+	unsigned short unroll = 0;
+	bool ivdep = false;
+	if (c_parser_peek_token (parser)->pragma_kind == PRAGMA_IVDEP)
+	  ivdep = c_parse_pragma_ivdep (parser);
+	if (c_parser_peek_token (parser)->pragma_kind == PRAGMA_UNROLL)
+	  unroll = c_parser_pragma_unroll (parser);
 	if (!c_parser_next_token_is_keyword (parser, RID_FOR)
 	    && !c_parser_next_token_is_keyword (parser, RID_WHILE)
 	    && !c_parser_next_token_is_keyword (parser, RID_DO))
@@ -13301,11 +13362,11 @@  c_parser_pragma (c_parser *parser, enum pragma_context context, bool *if_p)
 	    return false;
 	  }
 	if (c_parser_next_token_is_keyword (parser, RID_FOR))
-	  c_parser_for_statement (parser, ivdep, unroll, if_p);
+	  c_parser_for_statement (parser, ivdep, unroll, novector, if_p);
 	else if (c_parser_next_token_is_keyword (parser, RID_WHILE))
-	  c_parser_while_statement (parser, ivdep, unroll, if_p);
+	  c_parser_while_statement (parser, ivdep, unroll, novector, if_p);
 	else
-	  c_parser_do_statement (parser, ivdep, unroll);
+	  c_parser_do_statement (parser, ivdep, unroll, novector);
       }
       return true;
 
diff --git a/gcc/cp/cp-tree.def b/gcc/cp/cp-tree.def
index 0e66ca70e00caa1dc4beada1024ace32954e2aaf..c13c8ea98a523c4ef1c55a11e02d5da9db7e367e 100644
--- a/gcc/cp/cp-tree.def
+++ b/gcc/cp/cp-tree.def
@@ -305,8 +305,8 @@  DEFTREECODE (IF_STMT, "if_stmt", tcc_statement, 4)
 
 /* Used to represent a range-based `for' statement. The operands are
    RANGE_FOR_DECL, RANGE_FOR_EXPR, RANGE_FOR_BODY, RANGE_FOR_SCOPE,
-   RANGE_FOR_UNROLL, and RANGE_FOR_INIT_STMT, respectively.  Only used in
-   templates.  */
+   RANGE_FOR_UNROLL, RANGE_FOR_NOVECTOR and RANGE_FOR_INIT_STMT,
+   respectively.  Only used in templates.  */
 DEFTREECODE (RANGE_FOR_STMT, "range_for_stmt", tcc_statement, 6)
 
 /* Used to represent an expression statement.  Use `EXPR_STMT_EXPR' to
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 8398223311194837441107cb335d497ff5f5ec1c..50b0f20817a168b5e9ac58db59ad44233f079e11 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -5377,6 +5377,7 @@  get_vec_init_expr (tree t)
 #define RANGE_FOR_UNROLL(NODE)	TREE_OPERAND (RANGE_FOR_STMT_CHECK (NODE), 4)
 #define RANGE_FOR_INIT_STMT(NODE) TREE_OPERAND (RANGE_FOR_STMT_CHECK (NODE), 5)
 #define RANGE_FOR_IVDEP(NODE)	TREE_LANG_FLAG_6 (RANGE_FOR_STMT_CHECK (NODE))
+#define RANGE_FOR_NOVECTOR(NODE) TREE_LANG_FLAG_7 (RANGE_FOR_STMT_CHECK (NODE))
 
 /* STMT_EXPR accessor.  */
 #define STMT_EXPR_STMT(NODE)	TREE_OPERAND (STMT_EXPR_CHECK (NODE), 0)
@@ -7286,7 +7287,7 @@  extern bool maybe_clone_body			(tree);
 
 /* In parser.cc */
 extern tree cp_convert_range_for (tree, tree, tree, tree, unsigned int, bool,
-				  unsigned short);
+				  unsigned short, bool);
 extern void cp_convert_omp_range_for (tree &, vec<tree, va_gc> *, tree &,
 				      tree &, tree &, tree &, tree &, tree &);
 extern void cp_finish_omp_range_for (tree, tree);
@@ -7609,16 +7610,19 @@  extern void begin_else_clause			(tree);
 extern void finish_else_clause			(tree);
 extern void finish_if_stmt			(tree);
 extern tree begin_while_stmt			(void);
-extern void finish_while_stmt_cond	(tree, tree, bool, unsigned short);
+extern void finish_while_stmt_cond	(tree, tree, bool, unsigned short,
+					 bool);
 extern void finish_while_stmt			(tree);
 extern tree begin_do_stmt			(void);
 extern void finish_do_body			(tree);
-extern void finish_do_stmt		(tree, tree, bool, unsigned short);
+extern void finish_do_stmt		(tree, tree, bool, unsigned short,
+					 bool);
 extern tree finish_return_stmt			(tree);
 extern tree begin_for_scope			(tree *);
 extern tree begin_for_stmt			(tree, tree);
 extern void finish_init_stmt			(tree);
-extern void finish_for_cond		(tree, tree, bool, unsigned short);
+extern void finish_for_cond		(tree, tree, bool, unsigned short,
+					 bool);
 extern void finish_for_expr			(tree, tree);
 extern void finish_for_stmt			(tree);
 extern tree begin_range_for_stmt		(tree, tree);
diff --git a/gcc/cp/init.cc b/gcc/cp/init.cc
index af6e30f511e142c7a594e742d128b2bf0aa8fb8d..5b735b27e6f5bc6b439ae64665902f4f1ca76f95 100644
--- a/gcc/cp/init.cc
+++ b/gcc/cp/init.cc
@@ -4846,7 +4846,7 @@  build_vec_init (tree base, tree maxindex, tree init,
       finish_init_stmt (for_stmt);
       finish_for_cond (build2 (GT_EXPR, boolean_type_node, iterator,
 			       build_int_cst (TREE_TYPE (iterator), -1)),
-		       for_stmt, false, 0);
+		       for_stmt, false, 0, false);
       /* We used to pass this decrement to finish_for_expr; now we add it to
 	 elt_init below so it's part of the same full-expression as the
 	 initialization, and thus happens before any potentially throwing
diff --git a/gcc/cp/method.cc b/gcc/cp/method.cc
index 91cf943f11089c0e6bcbe8377daa4e016f956d56..fce49c796199c2c65cd70684e2942fea1b6b2ebd 100644
--- a/gcc/cp/method.cc
+++ b/gcc/cp/method.cc
@@ -1645,7 +1645,8 @@  build_comparison_op (tree fndecl, bool defining, tsubst_flags_t complain)
 		      add_stmt (idx);
 		      finish_init_stmt (for_stmt);
 		      finish_for_cond (build2 (LE_EXPR, boolean_type_node, idx,
-					       maxval), for_stmt, false, 0);
+					       maxval), for_stmt, false, 0,
+					       false);
 		      finish_for_expr (cp_build_unary_op (PREINCREMENT_EXPR,
 							  TARGET_EXPR_SLOT (idx),
 							  false, complain),
diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index dd3665c8ccf48a8a0b1ba2c06400fe50999ea240..0bc110121d51ee13258b7ff0e4ad7851b4eae78e 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -2324,15 +2324,15 @@  static tree cp_parser_selection_statement
 static tree cp_parser_condition
   (cp_parser *);
 static tree cp_parser_iteration_statement
-  (cp_parser *, bool *, bool, unsigned short);
+  (cp_parser *, bool *, bool, unsigned short, bool);
 static bool cp_parser_init_statement
   (cp_parser *, tree *decl);
 static tree cp_parser_for
-  (cp_parser *, bool, unsigned short);
+  (cp_parser *, bool, unsigned short, bool);
 static tree cp_parser_c_for
-  (cp_parser *, tree, tree, bool, unsigned short);
+  (cp_parser *, tree, tree, bool, unsigned short, bool);
 static tree cp_parser_range_for
-  (cp_parser *, tree, tree, tree, bool, unsigned short, bool);
+  (cp_parser *, tree, tree, tree, bool, unsigned short, bool, bool);
 static void do_range_for_auto_deduction
   (tree, tree, tree, unsigned int);
 static tree cp_parser_perform_range_for_lookup
@@ -12414,7 +12414,8 @@  cp_parser_statement (cp_parser* parser, tree in_statement_expr,
 	case RID_DO:
 	case RID_FOR:
 	  std_attrs = process_stmt_hotness_attribute (std_attrs, attrs_loc);
-	  statement = cp_parser_iteration_statement (parser, if_p, false, 0);
+	  statement = cp_parser_iteration_statement (parser, if_p, false, 0,
+						     false);
 	  break;
 
 	case RID_BREAK:
@@ -13594,7 +13595,8 @@  cp_parser_condition (cp_parser* parser)
    not included. */
 
 static tree
-cp_parser_for (cp_parser *parser, bool ivdep, unsigned short unroll)
+cp_parser_for (cp_parser *parser, bool ivdep, unsigned short unroll,
+	       bool novector)
 {
   tree init, scope, decl;
   bool is_range_for;
@@ -13624,14 +13626,14 @@  cp_parser_for (cp_parser *parser, bool ivdep, unsigned short unroll)
 
   if (is_range_for)
     return cp_parser_range_for (parser, scope, init, decl, ivdep, unroll,
-				false);
+				novector, false);
   else
-    return cp_parser_c_for (parser, scope, init, ivdep, unroll);
+    return cp_parser_c_for (parser, scope, init, ivdep, unroll, novector);
 }
 
 static tree
 cp_parser_c_for (cp_parser *parser, tree scope, tree init, bool ivdep,
-		 unsigned short unroll)
+		 unsigned short unroll, bool novector)
 {
   /* Normal for loop */
   tree condition = NULL_TREE;
@@ -13658,7 +13660,13 @@  cp_parser_c_for (cp_parser *parser, tree scope, tree init, bool ivdep,
 		       "%<GCC unroll%> pragma");
       condition = error_mark_node;
     }
-  finish_for_cond (condition, stmt, ivdep, unroll);
+  else if (novector)
+    {
+      cp_parser_error (parser, "missing loop condition in loop with "
+		       "%<GCC novector%> pragma");
+      condition = error_mark_node;
+    }
+  finish_for_cond (condition, stmt, ivdep, unroll, novector);
   /* Look for the `;'.  */
   cp_parser_require (parser, CPP_SEMICOLON, RT_SEMICOLON);
 
@@ -13682,7 +13690,8 @@  cp_parser_c_for (cp_parser *parser, tree scope, tree init, bool ivdep,
 
 static tree
 cp_parser_range_for (cp_parser *parser, tree scope, tree init, tree range_decl,
-		     bool ivdep, unsigned short unroll, bool is_omp)
+		     bool ivdep, unsigned short unroll, bool novector,
+		     bool is_omp)
 {
   tree stmt, range_expr;
   auto_vec <cxx_binding *, 16> bindings;
@@ -13758,6 +13767,8 @@  cp_parser_range_for (cp_parser *parser, tree scope, tree init, tree range_decl,
 	RANGE_FOR_IVDEP (stmt) = 1;
       if (unroll)
 	RANGE_FOR_UNROLL (stmt) = build_int_cst (integer_type_node, unroll);
+      if (novector)
+	RANGE_FOR_NOVECTOR (stmt) = 1;
       finish_range_for_decl (stmt, range_decl, range_expr);
       if (!type_dependent_expression_p (range_expr)
 	  /* do_auto_deduction doesn't mess with template init-lists.  */
@@ -13770,7 +13781,7 @@  cp_parser_range_for (cp_parser *parser, tree scope, tree init, tree range_decl,
       stmt = begin_for_stmt (scope, init);
       stmt = cp_convert_range_for (stmt, range_decl, range_expr,
 				   decomp_first_name, decomp_cnt, ivdep,
-				   unroll);
+				   unroll, novector);
     }
   return stmt;
 }
@@ -13948,7 +13959,7 @@  warn_for_range_copy (tree decl, tree expr)
 tree
 cp_convert_range_for (tree statement, tree range_decl, tree range_expr,
 		      tree decomp_first_name, unsigned int decomp_cnt,
-		      bool ivdep, unsigned short unroll)
+		      bool ivdep, unsigned short unroll, bool novector)
 {
   tree begin, end;
   tree iter_type, begin_expr, end_expr;
@@ -14008,7 +14019,7 @@  cp_convert_range_for (tree statement, tree range_decl, tree range_expr,
 				 begin, ERROR_MARK,
 				 end, ERROR_MARK,
 				 NULL_TREE, NULL, tf_warning_or_error);
-  finish_for_cond (condition, statement, ivdep, unroll);
+  finish_for_cond (condition, statement, ivdep, unroll, novector);
 
   /* The new increment expression.  */
   expression = finish_unary_op_expr (input_location,
@@ -14175,7 +14186,7 @@  cp_parser_range_for_member_function (tree range, tree identifier)
 
 static tree
 cp_parser_iteration_statement (cp_parser* parser, bool *if_p, bool ivdep,
-			       unsigned short unroll)
+			       unsigned short unroll, bool novector)
 {
   cp_token *token;
   enum rid keyword;
@@ -14209,7 +14220,7 @@  cp_parser_iteration_statement (cp_parser* parser, bool *if_p, bool ivdep,
 	parens.require_open (parser);
 	/* Parse the condition.  */
 	condition = cp_parser_condition (parser);
-	finish_while_stmt_cond (condition, statement, ivdep, unroll);
+	finish_while_stmt_cond (condition, statement, ivdep, unroll, novector);
 	/* Look for the `)'.  */
 	parens.require_close (parser);
 	/* Parse the dependent statement.  */
@@ -14244,7 +14255,7 @@  cp_parser_iteration_statement (cp_parser* parser, bool *if_p, bool ivdep,
 	/* Parse the expression.  */
 	expression = cp_parser_expression (parser);
 	/* We're done with the do-statement.  */
-	finish_do_stmt (expression, statement, ivdep, unroll);
+	finish_do_stmt (expression, statement, ivdep, unroll, novector);
 	/* Look for the `)'.  */
 	parens.require_close (parser);
 	/* Look for the `;'.  */
@@ -14258,7 +14269,7 @@  cp_parser_iteration_statement (cp_parser* parser, bool *if_p, bool ivdep,
 	matching_parens parens;
 	parens.require_open (parser);
 
-	statement = cp_parser_for (parser, ivdep, unroll);
+	statement = cp_parser_for (parser, ivdep, unroll, novector);
 
 	/* Look for the `)'.  */
 	parens.require_close (parser);
@@ -43815,7 +43826,7 @@  cp_parser_omp_for_loop (cp_parser *parser, enum tree_code code, tree clauses,
 	      cp_parser_require (parser, CPP_COLON, RT_COLON);
 
 	      init = cp_parser_range_for (parser, NULL_TREE, NULL_TREE, decl,
-					  false, 0, true);
+					  false, 0, true, false);
 
 	      cp_convert_omp_range_for (this_pre_body, for_block, decl,
 					orig_decl, init, orig_init,
@@ -49300,6 +49311,15 @@  cp_parser_pragma_unroll (cp_parser *parser, cp_token *pragma_tok)
   return unroll;
 }
 
+/* Parse a pragma GCC novector.  */
+
+static bool
+cp_parser_pragma_novector (cp_parser *parser, cp_token *pragma_tok)
+{
+  cp_parser_skip_to_pragma_eol (parser, pragma_tok);
+  return true;
+}
+
 /* Normal parsing of a pragma token.  Here we can (and must) use the
    regular lexer.  */
 
@@ -49613,17 +49633,33 @@  cp_parser_pragma (cp_parser *parser, enum pragma_context context, bool *if_p)
 	    break;
 	  }
 	const bool ivdep = cp_parser_pragma_ivdep (parser, pragma_tok);
-	unsigned short unroll;
+	unsigned short unroll = 0;
+	bool novector = false;
 	cp_token *tok = cp_lexer_peek_token (the_parser->lexer);
-	if (tok->type == CPP_PRAGMA
-	    && cp_parser_pragma_kind (tok) == PRAGMA_UNROLL)
+
+	while (tok->type == CPP_PRAGMA)
 	  {
-	    tok = cp_lexer_consume_token (parser->lexer);
-	    unroll = cp_parser_pragma_unroll (parser, tok);
-	    tok = cp_lexer_peek_token (the_parser->lexer);
+	    switch (cp_parser_pragma_kind (tok))
+	      {
+		case PRAGMA_UNROLL:
+		  {
+		    tok = cp_lexer_consume_token (parser->lexer);
+		    unroll = cp_parser_pragma_unroll (parser, tok);
+		    tok = cp_lexer_peek_token (the_parser->lexer);
+		    break;
+		  }
+		case PRAGMA_NOVECTOR:
+		  {
+		    tok = cp_lexer_consume_token (parser->lexer);
+		    novector = cp_parser_pragma_novector (parser, tok);
+		    tok = cp_lexer_peek_token (the_parser->lexer);
+		    break;
+		  }
+		default:
+		  gcc_unreachable ();
+	      }
 	  }
-	else
-	  unroll = 0;
+
 	if (tok->type != CPP_KEYWORD
 	    || (tok->keyword != RID_FOR
 		&& tok->keyword != RID_WHILE
@@ -49632,7 +49668,7 @@  cp_parser_pragma (cp_parser *parser, enum pragma_context context, bool *if_p)
 	    cp_parser_error (parser, "for, while or do statement expected");
 	    return false;
 	  }
-	cp_parser_iteration_statement (parser, if_p, ivdep, unroll);
+	cp_parser_iteration_statement (parser, if_p, ivdep, unroll, novector);
 	return true;
       }
 
@@ -49646,17 +49682,82 @@  cp_parser_pragma (cp_parser *parser, enum pragma_context context, bool *if_p)
 	  }
 	const unsigned short unroll
 	  = cp_parser_pragma_unroll (parser, pragma_tok);
-	bool ivdep;
+	bool ivdep = false;
+	bool novector = false;
 	cp_token *tok = cp_lexer_peek_token (the_parser->lexer);
-	if (tok->type == CPP_PRAGMA
-	    && cp_parser_pragma_kind (tok) == PRAGMA_IVDEP)
+
+	while (tok->type == CPP_PRAGMA)
 	  {
-	    tok = cp_lexer_consume_token (parser->lexer);
-	    ivdep = cp_parser_pragma_ivdep (parser, tok);
-	    tok = cp_lexer_peek_token (the_parser->lexer);
+	    switch (cp_parser_pragma_kind (tok))
+	      {
+		case PRAGMA_IVDEP:
+		  {
+		    tok = cp_lexer_consume_token (parser->lexer);
+		    ivdep = cp_parser_pragma_ivdep (parser, tok);
+		    tok = cp_lexer_peek_token (the_parser->lexer);
+		    break;
+		  }
+		case PRAGMA_NOVECTOR:
+		  {
+		    tok = cp_lexer_consume_token (parser->lexer);
+		    novector = cp_parser_pragma_novector (parser, tok);
+		    tok = cp_lexer_peek_token (the_parser->lexer);
+		    break;
+		  }
+		default:
+		  gcc_unreachable ();
+	      }
 	  }
-	else
-	  ivdep = false;
+
+	if (tok->type != CPP_KEYWORD
+	    || (tok->keyword != RID_FOR
+		&& tok->keyword != RID_WHILE
+		&& tok->keyword != RID_DO))
+	  {
+	    cp_parser_error (parser, "for, while or do statement expected");
+	    return false;
+	  }
+	cp_parser_iteration_statement (parser, if_p, ivdep, unroll, novector);
+	return true;
+      }
+
+    case PRAGMA_NOVECTOR:
+      {
+	if (context == pragma_external)
+	  {
+	    error_at (pragma_tok->location,
+		      "%<#pragma GCC novector%> must be inside a function");
+	    break;
+	  }
+	const bool novector
+	  = cp_parser_pragma_novector (parser, pragma_tok);
+	bool ivdep = false;
+	unsigned short unroll;
+	cp_token *tok = cp_lexer_peek_token (the_parser->lexer);
+
+	while (tok->type == CPP_PRAGMA)
+	  {
+	    switch (cp_parser_pragma_kind (tok))
+	      {
+		case PRAGMA_IVDEP:
+		  {
+		    tok = cp_lexer_consume_token (parser->lexer);
+		    ivdep = cp_parser_pragma_ivdep (parser, tok);
+		    tok = cp_lexer_peek_token (the_parser->lexer);
+		    break;
+		  }
+		case PRAGMA_UNROLL:
+		  {
+		    tok = cp_lexer_consume_token (parser->lexer);
+		    unroll = cp_parser_pragma_unroll (parser, tok);
+		    tok = cp_lexer_peek_token (the_parser->lexer);
+		    break;
+		  }
+		default:
+		  gcc_unreachable ();
+	      }
+	  }
+
 	if (tok->type != CPP_KEYWORD
 	    || (tok->keyword != RID_FOR
 		&& tok->keyword != RID_WHILE
@@ -49665,7 +49766,7 @@  cp_parser_pragma (cp_parser *parser, enum pragma_context context, bool *if_p)
 	    cp_parser_error (parser, "for, while or do statement expected");
 	    return false;
 	  }
-	cp_parser_iteration_statement (parser, if_p, ivdep, unroll);
+	cp_parser_iteration_statement (parser, if_p, ivdep, unroll, novector);
 	return true;
       }
 
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 2345a18becc1160b9d12f3d88cccb66c8917373c..7b0d01a90e3c4012ec603ebe04cbbb31a7dd1570 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -19036,7 +19036,7 @@  tsubst_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl)
       RECUR (FOR_INIT_STMT (t));
       finish_init_stmt (stmt);
       tmp = RECUR (FOR_COND (t));
-      finish_for_cond (tmp, stmt, false, 0);
+      finish_for_cond (tmp, stmt, false, 0, false);
       tmp = RECUR (FOR_EXPR (t));
       finish_for_expr (tmp, stmt);
       {
@@ -19073,6 +19073,7 @@  tsubst_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl)
 	  {
 	    RANGE_FOR_IVDEP (stmt) = RANGE_FOR_IVDEP (t);
 	    RANGE_FOR_UNROLL (stmt) = RANGE_FOR_UNROLL (t);
+	    RANGE_FOR_NOVECTOR (stmt) = RANGE_FOR_NOVECTOR (t);
 	    finish_range_for_decl (stmt, decl, expr);
 	    if (decomp_first && decl != error_mark_node)
 	      cp_finish_decomp (decl, decomp_first, decomp_cnt);
@@ -19083,7 +19084,8 @@  tsubst_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl)
 				     ? tree_to_uhwi (RANGE_FOR_UNROLL (t)) : 0);
 	    stmt = cp_convert_range_for (stmt, decl, expr,
 					 decomp_first, decomp_cnt,
-					 RANGE_FOR_IVDEP (t), unroll);
+					 RANGE_FOR_IVDEP (t), unroll,
+					 RANGE_FOR_NOVECTOR (t));
 	  }
 
 	bool prev = note_iteration_stmt_body_start ();
@@ -19096,7 +19098,7 @@  tsubst_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl)
     case WHILE_STMT:
       stmt = begin_while_stmt ();
       tmp = RECUR (WHILE_COND (t));
-      finish_while_stmt_cond (tmp, stmt, false, 0);
+      finish_while_stmt_cond (tmp, stmt, false, 0, false);
       {
 	bool prev = note_iteration_stmt_body_start ();
 	RECUR (WHILE_BODY (t));
@@ -19114,7 +19116,7 @@  tsubst_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl)
       }
       finish_do_body (stmt);
       tmp = RECUR (DO_COND (t));
-      finish_do_stmt (tmp, stmt, false, 0);
+      finish_do_stmt (tmp, stmt, false, 0, false);
       break;
 
     case IF_STMT:
diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index 8fb47fd179eb2af2e82bf31d188023e9b9d41de9..b79975109c22ebcfcb060b4f20f32f69f3c3c444 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -1148,7 +1148,7 @@  begin_while_stmt (void)
 
 void
 finish_while_stmt_cond (tree cond, tree while_stmt, bool ivdep,
-			unsigned short unroll)
+			unsigned short unroll, bool novector)
 {
   cond = maybe_convert_cond (cond);
   finish_cond (&WHILE_COND (while_stmt), cond);
@@ -1168,6 +1168,13 @@  finish_while_stmt_cond (tree cond, tree while_stmt, bool ivdep,
 						     annot_expr_unroll_kind),
 				      build_int_cst (integer_type_node,
 						     unroll));
+  if (novector && cond != error_mark_node)
+    WHILE_COND (while_stmt) = build3 (ANNOTATE_EXPR,
+				      TREE_TYPE (WHILE_COND (while_stmt)),
+				      WHILE_COND (while_stmt),
+				      build_int_cst (integer_type_node,
+						     annot_expr_no_vector_kind),
+				      integer_zero_node);
   simplify_loop_decl_cond (&WHILE_COND (while_stmt), WHILE_BODY (while_stmt));
 }
 
@@ -1212,7 +1219,8 @@  finish_do_body (tree do_stmt)
    COND is as indicated.  */
 
 void
-finish_do_stmt (tree cond, tree do_stmt, bool ivdep, unsigned short unroll)
+finish_do_stmt (tree cond, tree do_stmt, bool ivdep, unsigned short unroll,
+		bool novector)
 {
   cond = maybe_convert_cond (cond);
   end_maybe_infinite_loop (cond);
@@ -1229,6 +1237,10 @@  finish_do_stmt (tree cond, tree do_stmt, bool ivdep, unsigned short unroll)
     cond = build3 (ANNOTATE_EXPR, TREE_TYPE (cond), cond,
 		   build_int_cst (integer_type_node, annot_expr_unroll_kind),
 		   build_int_cst (integer_type_node, unroll));
+  if (novector && cond != error_mark_node)
+    cond = build3 (ANNOTATE_EXPR, TREE_TYPE (cond), cond,
+		   build_int_cst (integer_type_node, annot_expr_no_vector_kind),
+		   integer_zero_node);
   DO_COND (do_stmt) = cond;
 }
 
@@ -1325,7 +1337,7 @@  finish_init_stmt (tree for_stmt)
    FOR_STMT.  */
 
 void
-finish_for_cond (tree cond, tree for_stmt, bool ivdep, unsigned short unroll)
+finish_for_cond (tree cond, tree for_stmt, bool ivdep, unsigned short unroll, bool novector)
 {
   cond = maybe_convert_cond (cond);
   finish_cond (&FOR_COND (for_stmt), cond);
@@ -1345,6 +1357,13 @@  finish_for_cond (tree cond, tree for_stmt, bool ivdep, unsigned short unroll)
 						 annot_expr_unroll_kind),
 				  build_int_cst (integer_type_node,
 						 unroll));
+  if (novector && cond != error_mark_node)
+    FOR_COND (for_stmt) = build3 (ANNOTATE_EXPR,
+				  TREE_TYPE (FOR_COND (for_stmt)),
+				  FOR_COND (for_stmt),
+				  build_int_cst (integer_type_node,
+						 annot_expr_no_vector_kind),
+				  integer_zero_node);
   simplify_loop_decl_cond (&FOR_COND (for_stmt), FOR_BODY (for_stmt));
 }
 
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 3040a9bdea65d27f8d20572b4ed37375f5fe949b..baac6643d1abbf33d592e68aca49ac83e3c29188 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -24349,6 +24349,25 @@  void ignore_vec_dep (int *a, int k, int c, int m)
 @}
 @end smallexample
 
+@cindex pragma GCC novector
+@item #pragma GCC novector
+
+With this pragma, the programmer asserts that the following loop should be
+prevented from executing concurrently with SIMD (single instruction multiple
+data) instructions.
+
+For example, the compiler cannot vectorize the following loop with the pragma:
+
+@smallexample
+void foo (int n, int *a, int *b, int *c)
+@{
+  int i, j;
+#pragma GCC novector
+  for (i = 0; i < n; ++i)
+    a[i] = b[i] + c[i];
+@}
+@end smallexample
+
 @cindex pragma GCC unroll @var{n}
 @item #pragma GCC unroll @var{n}
 
diff --git a/gcc/testsuite/g++.dg/vect/vect-novector-pragma.cc b/gcc/testsuite/g++.dg/vect/vect-novector-pragma.cc
new file mode 100644
index 0000000000000000000000000000000000000000..4667935b641a06e3004904dc86c4513a78736f04
--- /dev/null
+++ b/gcc/testsuite/g++.dg/vect/vect-novector-pragma.cc
@@ -0,0 +1,29 @@ 
+/* { dg-do compile } */
+/* { dg-require-effective-target vect_int } */
+
+#include <vector>
+
+void f4 (std::vector<int> a, std::vector<int> b, int n)
+{
+    int i = 0;
+#pragma GCC novector
+    while (i < (n & -8))
+      {
+        a[i] += b[i];
+        i++;
+      }
+}
+
+
+void f5 (std::vector<int> a, std::vector<int> b, int n)
+{
+    int i = 0;
+#pragma GCC novector
+    for (auto x : b)
+      {
+        a[i] += x;
+        i++;
+      }
+}
+
+/* { dg-final { scan-tree-dump-not "LOOP VECTORIZED" "vect" } } */
diff --git a/gcc/testsuite/gcc.dg/vect/vect-novector-pragma.c b/gcc/testsuite/gcc.dg/vect/vect-novector-pragma.c
new file mode 100644
index 0000000000000000000000000000000000000000..c4b3957711db8f78d26a32634e9bbfdc11a33302
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-novector-pragma.c
@@ -0,0 +1,34 @@ 
+/* { dg-do compile } */
+/* { dg-require-effective-target vect_int } */
+
+void f1 (int * restrict a, int * restrict b, int n)
+{
+#pragma GCC novector
+    for (int i = 0; i < (n & -8); i++)
+      a[i] += b[i];
+}
+
+void f2 (int * restrict a, int * restrict b, int n)
+{
+    int i = 0;
+#pragma GCC novector
+    do
+      {
+        a[i] += b[i];
+        i++;
+      }
+    while (i < (n & -8));
+}
+
+void f3 (int * restrict a, int * restrict b, int n)
+{
+    int i = 0;
+#pragma GCC novector
+    while (i < (n & -8))
+      {
+        a[i] += b[i];
+        i++;
+      }
+}
+
+/* { dg-final { scan-tree-dump-not "LOOP VECTORIZED" "vect" } } */
diff --git a/gcc/tree-core.h b/gcc/tree-core.h
index c48a12b378f0b3086747bee43b38e2da3f90b24d..9268a0668390192caac9efaade0a53d9359cf9a7 100644
--- a/gcc/tree-core.h
+++ b/gcc/tree-core.h
@@ -1063,6 +1063,7 @@  struct GTY(()) tree_base {
       unsigned lang_flag_4 : 1;
       unsigned lang_flag_5 : 1;
       unsigned lang_flag_6 : 1;
+      unsigned lang_flag_7 : 1;
       unsigned saturating_flag : 1;
 
       unsigned unsigned_flag : 1;
@@ -1071,7 +1072,7 @@  struct GTY(()) tree_base {
       unsigned nameless_flag : 1;
       unsigned atomic_flag : 1;
       unsigned unavailable_flag : 1;
-      unsigned spare0 : 2;
+      unsigned spare0 : 1;
 
       unsigned spare1 : 8;
 
diff --git a/gcc/tree.h b/gcc/tree.h
index 1854fe4a7d4d25b0cb55ee70402d5721f8b629ba..e96e8884bf68de77d19c95a87ae1c147460c23df 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -1112,6 +1112,8 @@  extern void omp_clause_range_check_failed (const_tree, const char *, int,
   (TREE_NOT_CHECK2 (NODE, TREE_VEC, SSA_NAME)->base.u.bits.lang_flag_5)
 #define TREE_LANG_FLAG_6(NODE) \
   (TREE_NOT_CHECK2 (NODE, TREE_VEC, SSA_NAME)->base.u.bits.lang_flag_6)
+#define TREE_LANG_FLAG_7(NODE) \
+  (TREE_NOT_CHECK2 (NODE, TREE_VEC, SSA_NAME)->base.u.bits.lang_flag_7)
 
 /* Define additional fields and accessors for nodes representing constants.  */