diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 3eaa1681a02..27901962778 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2007-06-20  Zdenek Dvorak  <dvorakz@suse.cz>
+
+	PR rtl-optimization/32405
+	* loop-iv.c (iv_get_reaching_def): Fail for partial defs.
+
 2007-06-20  Jakub Jelinek  <jakub@redhat.com>
 
 	* Makefile.in (omega.o): Depend on $(DIAGNOSTIC_H).
diff --git a/gcc/loop-iv.c b/gcc/loop-iv.c
index 5016aaf46ef..f87f968022a 100644
--- a/gcc/loop-iv.c
+++ b/gcc/loop-iv.c
@@ -347,6 +347,11 @@ iv_get_reaching_def (rtx insn, rtx reg, struct df_ref **def)
     return GRD_INVALID;
 
   adef = DF_REF_CHAIN (use)->ref;
+
+  /* We do not handle setting only part of the register.  */
+  if (adef->flags & DF_REF_READ_WRITE)
+    return GRD_INVALID;
+
   def_insn = DF_REF_INSN (adef);
   def_bb = DF_REF_BB (adef);
   use_bb = BLOCK_FOR_INSN (insn);