Improve max_insns_skipped logic

Improve the logic when setting max_insns_skipped.  Limit the maximum size of IT
to MAX_INSN_PER_IT_BLOCK as otherwise multiple IT instructions are needed,
increasing codesize.  Given 4 works well for Thumb-2, use the same limit for ARM
for consistency.

    gcc/
	* config/arm/arm.c (arm_option_params_internal): Improve setting of
	max_insns_skipped.

From-SVN: r251720

gcc/ChangeLog

+2017-09-05  Wilco Dijkstra  <wdijkstr@arm.com>
+
+	* config/arm/arm.c (arm_option_params_internal): Improve setting of
+	max_insns_skipped.
+
 2017-09-05  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR target/59501

gcc/config/arm/arm.c

@@ -2873,20 +2873,12 @@ arm_option_params_internal (void)
       targetm.max_anchor_offset = TARGET_MAX_ANCHOR_OFFSET;
     }
 
-  if (optimize_size)
-    {
-      /* If optimizing for size, bump the number of instructions that we
-         are prepared to conditionally execute (even on a StrongARM).  */
-      max_insns_skipped = 6;
+  /* Increase the number of conditional instructions with -Os.  */
+  max_insns_skipped = optimize_size ? 4 : current_tune->max_insns_skipped;
 
   /* For THUMB2, we limit the conditional sequence to one IT block.  */
   if (TARGET_THUMB2)
-        max_insns_skipped = arm_restrict_it ? 1 : 4;
-    }
-  else
-    /* When -mrestrict-it is in use tone down the if-conversion.  */
-    max_insns_skipped = (TARGET_THUMB2 && arm_restrict_it)
-      ? 1 : current_tune->max_insns_skipped;
+    max_insns_skipped = MIN (max_insns_skipped, MAX_INSN_PER_IT_BLOCK);
 }
 
 /* True if -mflip-thumb should next add an attribute for the default