From 90eb3072e3353e49d60c903664b2e9e2efc5d1de Mon Sep 17 00:00:00 2001
From: jakub <jakub@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Mon, 6 Jun 2011 17:16:35 +0000
Subject: [PATCH] 	PR c++/49264
 	* gimple-fold.c (fold_stmt_1): Don't try to fold *& on the lhs
 	if stmt folded into nothing.
 	* tree-inline.c (fold_marked_statements): If a builtin at the
 	end of a bb folded into nothing, just update cgraph edges
 	and move to next bb.
 	* cgraph.c (cgraph_update_edges_for_call_stmt_node): Allow new_stmt
 	to be NULL.  Don't compute count and frequency if new_call is NULL.

	* g++.dg/opt/pr49264.C: New test.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-4_6-branch@174713 138bc75d-0d04-0410-961f-82ee72b054a4

index 64d278f..41265f8 100644
--- a/gcc/cgraph.c
+++ b/gcc/cgraph.c
@@ -1241,13 +1241,17 @@ cgraph_make_edge_direct (struct cgraph_edge *edge, struct cgraph_node *callee,
 
 /* Update or remove the corresponding cgraph edge if a GIMPLE_CALL
    OLD_STMT changed into NEW_STMT.  OLD_CALL is gimple_call_fndecl
-   of OLD_STMT if it was previously call statement.  */
+   of OLD_STMT if it was previously call statement.
+   If NEW_STMT is NULL, the call has been dropped without any
+   replacement.  */
 
 static void
 cgraph_update_edges_for_call_stmt_node (struct cgraph_node *node,
-					gimple old_stmt, tree old_call, gimple new_stmt)
+					gimple old_stmt, tree old_call,
+					gimple new_stmt)
 {
-  tree new_call = (is_gimple_call (new_stmt)) ? gimple_call_fndecl (new_stmt) : 0;
+  tree new_call = (new_stmt && is_gimple_call (new_stmt))
+		  ? gimple_call_fndecl (new_stmt) : 0;
 
   /* We are seeing indirect calls, then there is nothing to update.  */
   if (!new_call && !old_call)
@@ -1287,7 +1291,7 @@ cgraph_update_edges_for_call_stmt_node (struct cgraph_node *node,
 	  loop_nest = e->loop_nest;
 	  cgraph_remove_edge (e);
 	}
-      else
+      else if (new_call)
 	{
 	  /* We are seeing new direct call; compute profile info based on BB.  */
 	  basic_block bb = gimple_bb (new_stmt);
diff --git a/gcc/gimple-fold.c b/gcc/gimple-fold.c
index 910e3b0..cd8f409 100644
--- a/gcc/gimple-fold.c
+++ b/gcc/gimple-fold.c
@@ -1484,6 +1484,11 @@ fold_stmt_1 (gimple_stmt_iterator *gsi, bool inplace)
   bool changed = false;
   gimple stmt = gsi_stmt (*gsi);
   unsigned i;
+  gimple_stmt_iterator gsinext = *gsi;
+  gimple next_stmt;
+
+  gsi_next (&gsinext);
+  next_stmt = gsi_end_p (gsinext) ? NULL : gsi_stmt (gsinext);
 
   /* Fold the main computation performed by the statement.  */
   switch (gimple_code (stmt))
@@ -1572,10 +1577,19 @@ fold_stmt_1 (gimple_stmt_iterator *gsi, bool inplace)
     default:;
     }
 
+  /* If stmt folds into nothing and it was the last stmt in a bb,
+     don't call gsi_stmt.  */
+  if (gsi_end_p (*gsi))
+    {
+      gcc_assert (next_stmt == NULL);
+      return changed;
+    }
+
   stmt = gsi_stmt (*gsi);
 
-  /* Fold *& on the lhs.  */
-  if (gimple_has_lhs (stmt))
+  /* Fold *& on the lhs.  Don't do this if stmt folded into nothing,
+     as we'd changing the next stmt.  */
+  if (gimple_has_lhs (stmt) && stmt != next_stmt)
     {
       tree lhs = gimple_get_lhs (stmt);
       if (lhs && REFERENCE_CLASS_P (lhs))
new file mode 100644
index 0000000..dc23740
--- /dev/null
+++ b/gcc/testsuite/g++.dg/opt/pr49264.C
@@ -0,0 +1,19 @@
+// PR c++/49264
+// { dg-do compile }
+// { dg-options "-O2" }
+
+struct B { };
+struct A { char a[sizeof (B) + 1]; } a;
+
+static inline void
+foo (const B &b)
+{
+  __builtin_memcpy (&a, &b, sizeof (b));
+}
+
+void
+bar ()
+{
+  B c;
+  foo (c);
+}
diff --git a/gcc/tree-inline.c b/gcc/tree-inline.c
index ef3f1a3..a0162de 100644
--- a/gcc/tree-inline.c
+++ b/gcc/tree-inline.c
@@ -4117,6 +4117,14 @@ fold_marked_statements (int first, struct pointer_set_t *statements)
 		  if (fold_stmt (&gsi))
 		    {
 		      gimple new_stmt;
+		      /* If a builtin at the end of a bb folded into nothing,
+			 the following loop won't work.  */
+		      if (gsi_end_p (gsi))
+			{
+			  cgraph_update_edges_for_call_stmt (old_stmt,
+							     old_decl, NULL);
+			  break;
+			}
 		      if (gsi_end_p (i2))
 			i2 = gsi_start_bb (BASIC_BLOCK (first));
 		      else
-- 
1.7.0.4