diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 86a2f2d01db..a1cdc889b9a 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2012-04-30  Dodji Seketeli  <dodji@redhat.com>
+
+	Fix PCH crash on GTYed pointer-to-scalar field of a struct
+	* gengtype.c (write_types_process_field): Force second argument of
+	the call to the PCH object hierarchy walker to be 'x'.
+
 2012-04-30  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* config/i386/i386.c (ix86_handle_struct_attribute): Use the proper
diff --git a/gcc/gengtype.c b/gcc/gengtype.c
index abafaa9bc12..02d4c8c89d1 100644
--- a/gcc/gengtype.c
+++ b/gcc/gengtype.c
@@ -2930,7 +2930,26 @@ write_types_process_field (type_p f, const struct walk_type_data *d)
 	       wtd->subfield_marker_routine, cast, d->val);
       if (wtd->param_prefix)
 	{
-	  oprintf (d->of, ", %s", d->prev_val[3]);
+	  if (f->u.p->kind == TYPE_SCALAR)
+	    /* The current type is a pointer to a scalar (so not
+	       considered like a pointer to instances of user defined
+	       types) and we are seeing it; it means we must be even
+	       more careful about the second argument of the
+	       SUBFIELD_MARKER_ROUTINE call.  That argument must
+	       always be the instance of the type for which
+	       write_func_for_structure was called - this really is
+	       what the function SUBFIELD_MARKER_ROUTINE expects.
+	       That is, it must be an instance of the ORIG_S type
+	       parameter of write_func_for_structure.  The convention
+	       is that that argument must be "x" in that case (as set
+	       by write_func_for_structure).  The problem is, we can't
+	       count on d->prev_val[3] to be always set to "x" in that
+	       case.  Sometimes walk_type can set it to something else
+	       (to e.g cooperate with write_array when called from
+	       write_roots).  So let's set it to "x" here then.  */
+	    oprintf (d->of, ", x");
+	  else
+	    oprintf (d->of, ", %s", d->prev_val[3]);
 	  if (d->orig_s)
 	    {
 	      oprintf (d->of, ", gt_%s_", wtd->param_prefix);