[mid-end] [obvious] Cast to avoid -Wsign-compare warning from r279124

The previous revision adds a comparison that triggers a warning.
Here we simply cast the unsigned integer to a signed one before the
comparison.

gcc/ChangeLog:

2019-12-09  Matthew Malcomson  <matthew.malcomson@arm.com>

	* regstat.c (regstat_bb_compute_calls_crossed): Add a cast to
	avoid a warning.

From-SVN: r279126

gcc/ChangeLog

 2019-12-09  Matthew Malcomson  <matthew.malcomson@arm.com>
 
+	* regstat.c (regstat_bb_compute_calls_crossed): Add a cast to
+	avoid a warning.
+
+2019-12-09  Matthew Malcomson  <matthew.malcomson@arm.com>
+
 	PR middle-end/92410
 	* bb-reorder.c (pass_reorder_blocks::execute): Recompute
 	dataflow luids once basic blocks have been reordered.

gcc/regstat.c

@@ -324,7 +324,7 @@ regstat_bb_compute_calls_crossed (unsigned int bb_index, bitmap live)
 
   FOR_BB_INSNS_REVERSE (bb, insn)
     {
-      gcc_assert (INSN_UID (insn) < DF_INSN_SIZE ());
+      gcc_assert (INSN_UID (insn) < (int) DF_INSN_SIZE ());
       struct df_insn_info *insn_info = DF_INSN_INFO_GET (insn);
       unsigned int regno;