[Bug rtl-optimization/57940] New: [PATCH] Rerun df_analyze after delete_unmarked_insns during DCE

[makhaloff at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57940

            Bug ID: 57940
           Summary: [PATCH] Rerun df_analyze after delete_unmarked_insns
                    during DCE
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: makhaloff at gmail dot com

Hello!

If delete_unmarked_insns deletes some insn, DF state might be
out of date, and, regs_ever_live might contain unused registers till the end.
Fixed by forcing regs_ever_live update and rerunning df_analyze () at
fini_dce().
I found this bug on my target (not included into main sources). But I can send
everything you need to reproduce this bug.
Using gcc-4.8.1 

2013-07-20  Alexey Makhalov  <makhal...@gmail.com>

    * dce.c (fini_dce): Call df_analyze again just in case
delete_unmarked_insns removed anything.

--- dce.c       (revision 361)
+++ dce.c       (working copy)
@@ -745,6 +745,12 @@
       bitmap_obstack_release (&dce_blocks_bitmap_obstack);
       bitmap_obstack_release (&dce_tmp_bitmap_obstack);
     }
+
+  if (!df_in_progress)
+    {
+      df_compute_regs_ever_live (true);
+      df_analyze ();
+    }
 }