re PR target/79404 (h8300: ICE at gcc/ira.c:5541 whilst building libgcc)

	PR target/79404
	* ira-costs.c (scan_one_insn): Initialize register move costs
	for pseudos seen in USE/CLOBBER insns.

From-SVN: r245436

gcc/ChangeLog

@@ -4,6 +4,10 @@
 
 2017-02-14 Jeff Law  <law@redhat.com>
 
+	PR target/79404
+	* ira-costs.c (scan_one_insn): Initialize register move costs
+	for pseudos seen in USE/CLOBBER insns.
+
 	PR tree-optimization/79095
 	* tree-vrp.c (extract_range_from_binary_expr_1): For EXACT_DIV_EXPR,
 	if the numerator has the range ~[0,0] make the resultant range ~[0,0].

gcc/ira-costs.c

@@ -1438,9 +1438,25 @@ scan_one_insn (rtx_insn *insn)
     return insn;
 
   pat_code = GET_CODE (PATTERN (insn));
-  if (pat_code == USE || pat_code == CLOBBER || pat_code == ASM_INPUT)
+  if (pat_code == ASM_INPUT)
     return insn;
 
+  /* If INSN is a USE/CLOBBER of a pseudo in a mode M then go ahead
+     and initialize the register move costs of mode M.
+
+     The pseudo may be related to another pseudo via a copy (implicit or
+     explicit) and if there are no mode M uses/sets of the original
+     pseudo, then we may leave the register move costs uninitialized for
+     mode M. */
+  if (pat_code == USE || pat_code == CLOBBER)
+    {
+      rtx x = XEXP (PATTERN (insn), 0);
+      if (GET_CODE (x) == REG
+	  && REGNO (x) >= FIRST_PSEUDO_REGISTER)
+        ira_init_register_move_cost_if_necessary (GET_MODE (x));
+      return insn;
+    }
+
   counted_mem = false;
   set = single_set (insn);
   extract_insn (insn);