[backport gcc-4.9/trunk r198896 <mikpe@it.uu.se>]

List-Archive: <http://gcc.gnu.org/ml/gcc-patches/>
From: Mike Stump <mikestump at comcast dot net>
Subject: web ICEs on subreg
Date: Fri, 10 May 2013 14:51:04 -0700

I have a instruction pattern for my port that reads in part:

  [(parallel [(set (subreg:DI (match_operand:TI 0 "register_operand" "=3Dr"=
) 0)
                   (mem:DI (plus:DI (match_operand:DI 1 "register_operand" =
"r")
                                    (match_operand:DI 2 "const_int_operand"=
 ""))))
              (set (subreg:DI (match_dup 0) 8)
                   (mem:DI (plus:DI (match_dup 1)
                                    (match_operand:DI 3 "const_int_operand"=
))))])]

The subreg seems to give web.c fits.  web is looking for the match_dup and =
failing to find it, due to the fact that DF_REF_LOC is of the form (subreg:=
DI (reg:TI 5) 8), not (reg:TI 5).  If I add a case for SUBREG like in the b=
elow, we can then find and process the subreg.

So, the question is, is the port completely wrong for trying to use subreg =
in this fashion?  If not, is processing subregs in this way the right way? =
 If yes, Ok?

gcc/

2013-05-14  Mike Stump  <mikestump@comcast.net>

	* web.c (union_match_dups): Also check DF_REF_REAL_LOC.

--- gcc-4.8.0/gcc/web.c.~1~	2013-01-10 21:38:27.000000000 +0100
+++ gcc-4.8.0/gcc/web.c	2013-05-18 12:09:15.336278228 +0200
@@ -132,14 +132,22 @@ union_match_dups (rtx insn, struct web_e
       ref = type == OP_IN ? use_link : def_link;
       entry = type == OP_IN ? use_entry : def_entry;
       for (; *ref; ref++)
-	if (DF_REF_LOC (*ref) == recog_data.operand_loc[op])
-	  break;
+	{
+	  if (DF_REF_LOC (*ref) == recog_data.operand_loc[op])
+	    break;
+	  if (DF_REF_REAL_LOC (*ref) == recog_data.operand_loc[op])
+	    break;
+	}
 
       if (!*ref && type == OP_INOUT)
 	{
 	  for (ref = use_link, entry = use_entry; *ref; ref++)
-	    if (DF_REF_LOC (*ref) == recog_data.operand_loc[op])
-	      break;
+	    {
+	      if (DF_REF_LOC (*ref) == recog_data.operand_loc[op])
+		break;
+	      if (DF_REF_REAL_LOC (*ref) == recog_data.operand_loc[op])
+		break;
+	    }
 	}
 
       gcc_assert (*ref);