[Bug rtl-optimization/51505] [4.5/4.6/4.7 Regression] ICE: in form_sum, at reload.c:5349 with -O --param max-cse-insns=1

[abel at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51505

--- Comment #9 from Andrey Belevantsev <abel at gcc dot gnu.org> 2012-01-18 
09:46:41 UTC ---
This seems like an overkill as we only need to remove a single vector.  The
below helper looks enough:

+/* Remove the EQ_USES vector for INSN assuming it exists.  */
+void
+df_ref_remove_eq_uses (rtx insn)
+{
+  struct df_insn_info *insn_info = DF_INSN_UID_GET (INSN_UID (insn));
+  df_mw_hardreg_chain_delete_eq_uses (insn_info);
+  df_ref_chain_delete (insn_info->eq_uses);
+  insn_info->eq_uses = df_null_ref_rec;
+}
+

The patch then just calls this after killing a note.