[Bug optimization/11162] new-ra bug

["matz at suse dot de" <gcc-bugzilla at gcc dot gnu dot org>]

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11162



------- Additional Comments From matz@suse.de  2003-06-12 06:08 -------
Subject: Re:  new-ra bug

On 11 Jun 2003, rth@gcc.gnu.org wrote:

> Moreover, I can't figure out why the USE is being added at all.

Crappy obsolete design ;-)  I didn't use mark_regs_live_at_end() to force
the return register live at the end, partly because I can basically only
deal with real register references (the flow.c code simply sets some bits
in the liveness bitmaps).  But it needs to be made live somehow, hence I
simply added such fake uses.  In the new-ra branch I added code to delete
these instructions after allocation again.  (Or rather I would have had,
had I committed ;( ).  Like the below patch.  It also fixes the testcase.

Somewhen I need to go over this again, to use something similar to the
mark_regs_live_at_end() function, because this method is bound to break
(for instance I only add the return value use, but not all the other regs
which that function might add).

Index: ra.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/ra.c,v
retrieving revision 1.8
diff -u -p -r1.8 ra.c
--- ra.c	7 Mar 2003 22:06:16 -0000	1.8
+++ ra.c	12 Jun 2003 06:06:03 -0000
@@ -669,6 +669,7 @@ reg_alloc ()
   int changed;
   FILE *ra_dump_file = rtl_dump_file;
   rtx last = get_last_insn ();
+  bitmap use_insns = BITMAP_XMALLOC ();

   if (! INSN_P (last))
     last = prev_real_insn (last);
@@ -686,11 +687,13 @@ reg_alloc ()
 	  last = bb->end;
 	  if (!INSN_P (last) || GET_CODE (PATTERN (last)) != USE)
 	    {
-	      rtx insns;
+	      rtx insn, insns;
 	      start_sequence ();
 	      use_return_register ();
 	      insns = get_insns ();
 	      end_sequence ();
+	      for (insn = insns; insn; insn = NEXT_INSN (insn))
+		bitmap_set_bit (use_insns, INSN_UID (insn));
 	      emit_insn_after (insns, last);
 	    }
 	}
@@ -868,6 +871,22 @@ reg_alloc ()
   no_new_pseudos = 1;
   rtl_dump_file = ra_dump_file;

+    {
+      edge e;
+      for (e = EXIT_BLOCK_PTR->pred; e; e = e->pred_next)
+	{
+	  basic_block bb = e->src;
+	  last = bb->end;
+	  for (last = bb->end; last; last = PREV_INSN (last))
+	    {
+	      if (last == bb->head)
+		break;
+	      if (bitmap_bit_p (use_insns, INSN_UID (last)))
+		delete_insn (last);
+	    }
+	}
+    }
+  BITMAP_XFREE (use_insns);
   /* Some spill insns could've been inserted after trapping calls, i.e.
      at the end of a basic block, which really ends at that call.
      Fixup that breakages by adjusting basic block boundaries.  */