Revert:
[PR106746] drop cselib addr lookup in debug insn mem

The testcase used to get scheduled differently depending on the
presence of debug insns with MEMs.  It's not clear to me why those
MEMs affected scheduling, but the cselib pre-canonicalization of the
MEM address is not used at all when analyzing debug insns, so the
memory allocation and lookup are pure waste.  Somehow, avoiding that
waste fixes the problem, or makes it go latent.

2023-01-19  Alexandre Oliva  <oliva@adacore.com>

	PR debug/106746
	* sched-deps.cc (sched_analyze_2): Skip cselib address lookup
	within debug insns.

--- gcc/sched-deps.cc
+++ gcc/sched-deps.cc
@@ -2605,26 +2605,26 @@ sched_analyze_2 (class deps_desc *deps, rtx x, rtx_insn *insn)
 
     case MEM:
       {
-	if (!DEBUG_INSN_P (insn))
-	  {
-	    /* Reading memory.  */
-	    rtx_insn_list *u;
-	    rtx_insn_list *pending;
-	    rtx_expr_list *pending_mem;
-	    rtx t = x;
+	/* Reading memory.  */
+	rtx_insn_list *u;
+	rtx_insn_list *pending;
+	rtx_expr_list *pending_mem;
+	rtx t = x;
 
-	    if (sched_deps_info->use_cselib)
-	      {
-		machine_mode address_mode = get_address_mode (t);
-
-		t = shallow_copy_rtx (t);
-		cselib_lookup_from_insn (XEXP (t, 0), address_mode, 1,
-					 GET_MODE (t), insn);
-		XEXP (t, 0)
-		  = cselib_subst_to_values_from_insn (XEXP (t, 0), GET_MODE (t),
-						      insn);
-	      }
+	if (sched_deps_info->use_cselib)
+	  {
+	    machine_mode address_mode = get_address_mode (t);
+
+	    t = shallow_copy_rtx (t);
+	    cselib_lookup_from_insn (XEXP (t, 0), address_mode, 1,
+				     GET_MODE (t), insn);
+	    XEXP (t, 0)
+	      = cselib_subst_to_values_from_insn (XEXP (t, 0), GET_MODE (t),
+						  insn);
+	  }
 
+	if (!DEBUG_INSN_P (insn))
+	  {
 	    t = canon_rtx (t);
 	    pending = deps->pending_read_insns;
 	    pending_mem = deps->pending_read_mems;