From: Jakub Jelinek <jakub@redhat.com>
Date: Mon, 25 Jun 2018 16:57:59 +0000 (+0200)
Subject: backport: re PR sanitizer/81212 (-Wreturn-type is disabled when used together with... 
X-Git-Tag: releases/gcc-6.5.0~241
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6028f46a2fdfe5116aadb5fb8f68e56b9c1b6fbc;p=thirdparty%2Fgcc.git

backport: re PR sanitizer/81212 (-Wreturn-type is disabled when used together with -fsanitize=return)

	Backported from mainline
	2017-12-02  Jakub Jelinek  <jakub@redhat.com>

	PR c++/81212
	* tree-cfg.c (pass_warn_function_return::execute): Handle
	__builtin_ubsan_handle_missing_return like __builtin_unreachable
	with BUILTINS_LOCATION.

	* g++.dg/ubsan/pr81212.C: New test.

From-SVN: r262042
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 310eda8082d8..e961c0e34222 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -3,6 +3,11 @@
 	Backported from mainline
 	2017-12-02  Jakub Jelinek  <jakub@redhat.com>
 
+	PR c++/81212
+	* tree-cfg.c (pass_warn_function_return::execute): Handle
+	__builtin_ubsan_handle_missing_return like __builtin_unreachable
+	with BUILTINS_LOCATION.
+
 	PR target/78643
 	PR target/80583
 	* expr.c (get_inner_reference): If DECL_MODE of a non-bitfield
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 204fea0c8f8a..67023267d1b3 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -3,6 +3,9 @@
 	Backported from mainline
 	2017-12-02  Jakub Jelinek  <jakub@redhat.com>
 
+	PR c++/81212
+	* g++.dg/ubsan/pr81212.C: New test.
+
 	PR target/78643
 	PR target/80583
 	* gcc.target/i386/pr80583.c: New test.
diff --git a/gcc/testsuite/g++.dg/ubsan/pr81212.C b/gcc/testsuite/g++.dg/ubsan/pr81212.C
new file mode 100644
index 000000000000..ce92a07dceb3
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ubsan/pr81212.C
@@ -0,0 +1,16 @@
+// PR c++/81212
+// { dg-do compile }
+// { dg-options "-Wreturn-type -fsanitize=return" }
+
+struct S
+{
+  S (void *);
+  void *s;
+};
+
+S
+foo (bool x, void *y)
+{
+  if (x)
+    return S (y);
+}	// { dg-warning "control reaches end of non-void function" }
diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
index 380f6898db75..983fd704f6bc 100644
--- a/gcc/tree-cfg.c
+++ b/gcc/tree-cfg.c
@@ -8752,7 +8752,6 @@ pass_warn_function_return::execute (function *fun)
      without returning a value.  */
   else if (warn_return_type
 	   && !TREE_NO_WARNING (fun->decl)
-	   && EDGE_COUNT (EXIT_BLOCK_PTR_FOR_FN (fun)->preds) > 0
 	   && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (fun->decl))))
     {
       FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR_FOR_FN (fun)->preds)
@@ -8766,11 +8765,40 @@ pass_warn_function_return::execute (function *fun)
 	      location = gimple_location (last);
 	      if (location == UNKNOWN_LOCATION)
 		location = fun->function_end_locus;
-	      warning_at (location, OPT_Wreturn_type, "control reaches end of non-void function");
+	      warning_at (location, OPT_Wreturn_type,
+			  "control reaches end of non-void function");
 	      TREE_NO_WARNING (fun->decl) = 1;
 	      break;
 	    }
 	}
+      /* -fsanitize=return turns fallthrough from the end of non-void function
+	 into __builtin___ubsan_handle_missing_return () call.
+	 Recognize those too.  */
+      basic_block bb;
+      if (!TREE_NO_WARNING (fun->decl) && (flag_sanitize & SANITIZE_RETURN))
+	FOR_EACH_BB_FN (bb, fun)
+	  if (EDGE_COUNT (bb->succs) == 0)
+	    {
+	      gimple *last = last_stmt (bb);
+	      const enum built_in_function ubsan_missing_ret
+		= BUILT_IN_UBSAN_HANDLE_MISSING_RETURN;
+	      if (last && gimple_call_builtin_p (last, ubsan_missing_ret))
+		{
+		  gimple_stmt_iterator gsi = gsi_for_stmt (last);
+		  gsi_prev_nondebug (&gsi);
+		  gimple *prev = gsi_stmt (gsi);
+		  if (prev == NULL)
+		    location = UNKNOWN_LOCATION;
+		  else
+		    location = gimple_location (prev);
+		  if (LOCATION_LOCUS (location) == UNKNOWN_LOCATION)
+		    location = fun->function_end_locus;
+		  warning_at (location, OPT_Wreturn_type,
+			      "control reaches end of non-void function");
+		  TREE_NO_WARNING (fun->decl) = 1;
+		  break;
+		}
+	    }
     }
   return 0;
 }