2017-12-18  Jakub Jelinek  <jakub@redhat.com>

	PR debug/83419
	* tree-iterator.c: Include options.h.
	(alloc_stmt_list): Clear TREE_SIDE_EFFECTS for a new node.
	(tsi_link_after): Set TREE_SIDE_EFFECTS when adding STATEMENT_LIST with
	TREE_SIDE_EFFECTS or non-DEBUG_BEGIN_STMT.
	(tsi_link_before): Likewise.  Formatting fix.
	(tsi_delink): Recompute TREE_SIDE_EFFECTS on removal.
	* gimplify.c (gimplify_statement_list): Clear TREE_SIDE_EFFECTS.

	* gcc.dg/pr83419.c: New test.

--- gcc/tree-iterator.c.jj	2017-12-12 09:48:26.000000000 +0100
+++ gcc/tree-iterator.c	2017-12-18 13:44:02.330719440 +0100
@@ -23,6 +23,7 @@ along with GCC; see the file COPYING3.
 #include "coretypes.h"
 #include "tree.h"
 #include "tree-iterator.h"
+#include "options.h"
 
 
 /* This is a cache of STATEMENT_LIST nodes.  We create and destroy them
@@ -41,7 +42,10 @@ alloc_stmt_list (void)
       TREE_SET_CODE (list, STATEMENT_LIST);
     }
   else
-    list = make_node (STATEMENT_LIST);
+    {
+      list = make_node (STATEMENT_LIST);
+      TREE_SIDE_EFFECTS (list) = 0;
+    }
   TREE_TYPE (list) = void_type_node;
   return list;
 }
@@ -127,6 +131,8 @@ tsi_link_before (tree_stmt_iterator *i,
 	  gcc_assert (head == tail);
 	  return;
 	}
+      if (TREE_SIDE_EFFECTS (t))
+	TREE_SIDE_EFFECTS (i->container) = 1;
     }
   else
     {
@@ -135,11 +141,10 @@ tsi_link_before (tree_stmt_iterator *i,
       head->next = NULL;
       head->stmt = t;
       tail = head;
+      if (TREE_CODE (t) != DEBUG_BEGIN_STMT)
+	TREE_SIDE_EFFECTS (i->container) = 1;
     }
 
-  if (TREE_CODE (t) != DEBUG_BEGIN_STMT)
-    TREE_SIDE_EFFECTS (i->container) = 1;
-
   cur = i->ptr;
 
   /* Link it into the list.  */
@@ -157,9 +162,9 @@ tsi_link_before (tree_stmt_iterator *i,
     {
       head->prev = STATEMENT_LIST_TAIL (i->container);
       if (head->prev)
-       head->prev->next = head;
+	head->prev->next = head;
       else
-       STATEMENT_LIST_HEAD (i->container) = head;
+	STATEMENT_LIST_HEAD (i->container) = head;
       STATEMENT_LIST_TAIL (i->container) = tail;
     }
 
@@ -204,6 +209,9 @@ tsi_link_after (tree_stmt_iterator *i, t
 	  gcc_assert (head == tail);
 	  return;
 	}
+
+      if (TREE_SIDE_EFFECTS (t))
+	TREE_SIDE_EFFECTS (i->container) = 1;
     }
   else
     {
@@ -212,10 +220,10 @@ tsi_link_after (tree_stmt_iterator *i, t
       head->next = NULL;
       head->stmt = t;
       tail = head;
-    }
 
-  if (TREE_CODE (t) != DEBUG_BEGIN_STMT)
-    TREE_SIDE_EFFECTS (i->container) = 1;
+      if (TREE_CODE (t) != DEBUG_BEGIN_STMT)
+	TREE_SIDE_EFFECTS (i->container) = 1;
+    }
 
   cur = i->ptr;
 
@@ -275,10 +283,30 @@ tsi_delink (tree_stmt_iterator *i)
   else
     STATEMENT_LIST_TAIL (i->container) = prev;
 
-  if (!next && !prev)
-    TREE_SIDE_EFFECTS (i->container) = 0;
-
   i->ptr = next;
+
+  if (!MAY_HAVE_DEBUG_MARKER_STMTS)
+    TREE_SIDE_EFFECTS (i->container) = 0;
+  else if (TREE_SIDE_EFFECTS (i->container))
+    {
+      while (next || prev)
+	{
+	  if (next)
+	    {
+	      if (TREE_CODE (next->stmt) != DEBUG_BEGIN_STMT)
+		break;
+	      next = next->next;
+	    }
+	  if (prev)
+	    {
+	      if (TREE_CODE (prev->stmt) != DEBUG_BEGIN_STMT)
+		break;
+	      prev = prev->prev;
+	    }
+	}
+      if (next == NULL && prev == NULL)
+	TREE_SIDE_EFFECTS (i->container) = 0;
+    }
 }
 
 /* Return the first expression in a sequence of COMPOUND_EXPRs, or in
--- gcc/gimplify.c.jj	2017-12-14 21:11:40.000000000 +0100
+++ gcc/gimplify.c	2017-12-18 10:17:07.922556324 +0100
@@ -1763,6 +1763,9 @@ gimplify_statement_list (tree *expr_p, g
 
   tree_stmt_iterator i = tsi_start (*expr_p);
 
+  /* No need to recompute TREE_SIDE_EFFECTS on removal, we are going to
+     delink everything.  */
+  TREE_SIDE_EFFECTS (*expr_p) = 0;
   while (!tsi_end_p (i))
     {
       gimplify_stmt (tsi_stmt_ptr (i), pre_p);
--- gcc/testsuite/gcc.dg/pr83419.c.jj	2017-12-18 10:08:24.214911480 +0100
+++ gcc/testsuite/gcc.dg/pr83419.c	2017-12-18 10:08:24.214911480 +0100
@@ -0,0 +1,16 @@
+/* PR debug/83419 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fcompare-debug" } */
+
+int a, b;
+void foo (int, ...);
+
+void
+bar (void)
+{
+  if (a || 1 == b)
+    foo (1);
+  else
+    0;
+  foo (1, 0);
+}