[backport proposed 4.8 fix for PR54128, which affects gcc-4.6 and newer <mikpe@it.uu.se>]

From: "Steve Ellcey " <sellcey at mips dot com>
Date: Fri, 31 Aug 2012 10:58:51 -0700
Subject: [Patch, PR 54128] ira.c change to fix mips bootstrap
List-Archive: <http://gcc.gnu.org/ml/gcc-patches/>

Here is my patch to fix the bootstrap comparision failure (PR 54128) on
MIPS.  The reason for the comparision failure was a difference in
register usage and I tracked it down to build_insn_chain which checked
all instructions for register usage in order to set the dead_or_set
and live_relevant_regs bitmaps instead of checking only non-debug
instructions.  Changing INSN_P to NONDEBUG_INSN_P in build_insn_chain
allowed me to bootstrap and caused no regressions.

OK to checkin?

Steve Ellcey
sellcey@mips.com


2012-08-31  Steve Ellcey  <sellcey@mips.com>

	PR bootstrap/54128
	* ira.c (build_insn_chain): Check only NONDEBUG instructions for
	register usage.

--- gcc-4.6.3/gcc/ira.c.~1~	2011-03-08 16:51:12.000000000 +0100
+++ gcc-4.6.3/gcc/ira.c	2012-09-01 13:58:12.000000000 +0200
@@ -2840,7 +2840,7 @@ build_insn_chain (void)
 	      c->insn = insn;
 	      c->block = bb->index;
 
-	      if (INSN_P (insn))
+	      if (NONDEBUG_INSN_P (insn))
 		for (def_rec = DF_INSN_UID_DEFS (uid); *def_rec; def_rec++)
 		  {
 		    df_ref def = *def_rec;
@@ -2931,7 +2931,7 @@ build_insn_chain (void)
 	      bitmap_and_compl_into (live_relevant_regs, elim_regset);
 	      bitmap_copy (&c->live_throughout, live_relevant_regs);
 
-	      if (INSN_P (insn))
+	      if (NONDEBUG_INSN_P (insn))
 		for (use_rec = DF_INSN_UID_USES (uid); *use_rec; use_rec++)
 		  {
 		    df_ref use = *use_rec;