[PATCH] Fix ira.c RTL sharing bug

[Jakub Jelinek]

Hi!

I've discovered today that RTL sharing verification has been disabled for
the last 3.5 years.  My --enable-checking=yes,rtl,extra bootstraps on
x86_64-linux and i686-linux revealed only two bugs.

Here is a fix for one of them, x can be shared with another insn that has
it in REG_EQUIV already, so we need to unshare it.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2016-11-30  Jakub Jelinek  <ja...@redhat.com>

        * ira.c (ira_update_equiv_info_by_shuffle_insn): Use copy_rtx
        for REG_EQUIV argument.

--- gcc/ira.c.jj        2016-11-18 18:11:24.000000000 +0100
+++ gcc/ira.c   2016-11-30 10:53:48.061704159 +0100
@@ -2647,7 +2647,7 @@ ira_update_equiv_info_by_shuffle_insn (i
        }
       if (find_reg_note (insn, REG_EQUIV, x) == NULL_RTX)
        {
-         note = set_unique_reg_note (insn, REG_EQUIV, x);
+         note = set_unique_reg_note (insn, REG_EQUIV, copy_rtx (x));
          gcc_assert (note != NULL_RTX);
          if (internal_flag_ira_verbose > 3 && ira_dump_file != NULL)
            {

        Jakub