go-gcc.cc (Gcc_backend::stack_allocation_expression): Clear the returned memory.

	* go-gcc.cc (Gcc_backend::stack_allocation_expression): Clear the
	returned memory.

From-SVN: r240840

gcc/go/ChangeLog

+2016-10-06  Chris Manghane  <cmang@google.com>
+
+	* go-gcc.cc (Gcc_backend::stack_allocation_expression): Clear the
+	returned memory.
+
 2016-09-27  Than McIntosh  <thanm@google.com>
 
 	* go-linemap.cc (Gcc_linemap::to_string): New method.

gcc/go/go-gcc.cc

@@ -2048,6 +2048,9 @@ Gcc_backend::stack_allocation_expression(int64_t size, Location location)
   tree alloca = builtin_decl_explicit(BUILT_IN_ALLOCA);
   tree size_tree = build_int_cst(integer_type_node, size);
   tree ret = build_call_expr_loc(location.gcc_location(), alloca, 1, size_tree);
+  tree memset = builtin_decl_explicit(BUILT_IN_MEMSET);
+  ret = build_call_expr_loc(location.gcc_location(), memset, 3,
+                            ret, integer_zero_node, size_tree);
   return this->make_expression(ret);
 }