diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 6e8285f837fc..64bdbe7929b6 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2007-09-18  Richard Sandiford  <rsandifo@nildram.co.uk>
+
+	* df-scan.c (df_notes_rescan): Do nothing if the instruction does
+	not yet have a basic block.
+	* dse.c (find_shift_sequence): Don't set DF_NO_INSN_RESCAN.
+
 2007-09-18  Richard Sandiford  <rsandifo@nildram.co.uk>
 
 	* config/mips/mips.c (mips_file_start): Add ".previous" directives
diff --git a/gcc/df-scan.c b/gcc/df-scan.c
index 6c2c6fad58a5..a1f71b03b6dd 100644
--- a/gcc/df-scan.c
+++ b/gcc/df-scan.c
@@ -2004,6 +2004,10 @@ df_notes_rescan (rtx insn)
   if (df->changeable_flags & DF_NO_INSN_RESCAN)
     return;
 
+  /* Do nothing if the insn hasn't been emitted yet.  */
+  if (!BLOCK_FOR_INSN (insn))
+    return;
+
   df_grow_bb_info (df_scan);
   df_grow_reg_info ();
 
diff --git a/gcc/dse.c b/gcc/dse.c
index 1aa1598e6b49..a9577830170f 100644
--- a/gcc/dse.c
+++ b/gcc/dse.c
@@ -1428,10 +1428,8 @@ find_shift_sequence (rtx read_reg,
       /* In theory we could also check for an ashr.  Ian Taylor knows
 	 of one dsp where the cost of these two was not the same.  But
 	 this really is a rare case anyway.  */
-      df_set_flags (DF_NO_INSN_RESCAN);
       target = expand_binop (new_mode, lshr_optab, new_reg,
 			     GEN_INT (shift), new_reg, 1, OPTAB_DIRECT);
-      df_clear_flags (DF_NO_INSN_RESCAN);
 
       if (target == new_reg)
 	{