diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 52d1a1abc4a..e95703f1e7f 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2010-02-11  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/42998
+	* tree-ssa-pre.c (create_expression_by_pieces): Treat
+	POINTER_PLUS_EXPR properly.
+
 2010-02-11  Sebastian Pop  <sebastian.pop@amd.com>
 	    Changpeng Fang  <changpeng.fang@amd.com>
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index b7ea3a29647..718b97d0f94 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2010-02-11  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/42998
+	* gcc.c-torture/compile/pr42998.c: New testcase.
+
 2010-02-10  Jason Merrill  <jason@redhat.com>
 
 	PR c++/41896
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr42998.c b/gcc/testsuite/gcc.c-torture/compile/pr42998.c
new file mode 100644
index 00000000000..7506d158129
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr42998.c
@@ -0,0 +1,15 @@
+void foo(void *);
+void bar(void *);
+void ndisc_fill_addr_option(unsigned char *opt, int data_len,
+			    unsigned short addr_type) 
+{
+  int pad;
+  if (addr_type == 32)
+    pad = 2;
+  else
+    pad = 0;
+  __builtin_memset(opt + 2, 0, pad);
+  opt += pad;
+  __builtin_constant_p(data_len) ? foo (opt+2) : bar (opt+2);
+}
+
diff --git a/gcc/tree-ssa-pre.c b/gcc/tree-ssa-pre.c
index 285b2c8b0b3..639adcefb23 100644
--- a/gcc/tree-ssa-pre.c
+++ b/gcc/tree-ssa-pre.c
@@ -3013,14 +3013,18 @@ create_expression_by_pieces (basic_block block, pre_expr expr,
 							 stmts, domstmt);
 	      if (!genop1 || !genop2)
 		return NULL_TREE;
-	      genop1 = fold_convert (TREE_TYPE (nary->op[0]),
-				     genop1);
 	      /* Ensure op2 is a sizetype for POINTER_PLUS_EXPR.  It
 		 may be a constant with the wrong type.  */
 	      if (nary->opcode == POINTER_PLUS_EXPR)
-		genop2 = fold_convert (sizetype, genop2);
+		{
+		  genop1 = fold_convert (nary->type, genop1);
+		  genop2 = fold_convert (sizetype, genop2);
+		}
 	      else
-		genop2 = fold_convert (TREE_TYPE (nary->op[1]), genop2);
+		{
+		  genop1 = fold_convert (TREE_TYPE (nary->op[0]), genop1);
+		  genop2 = fold_convert (TREE_TYPE (nary->op[1]), genop2);
+		}
 
 	      folded = fold_build2 (nary->opcode, nary->type,
 				    genop1, genop2);