Fix can_change_mode_class for big-endian on Arm

gcc/

	PR target/84711
	* config/arm/arm.c (arm_can_change_mode_class): Use GET_MODE_UNIT_SIZE
	instead of GET_MODE_SIZE when comparing Units.
	
gcc/testsuite/

	PR target/84711
	* gcc.target/arm/big-endian-subreg.c: New.

From-SVN: r262436

gcc/ChangeLog

 2018-07-05  Tamar Christina  <tamar.christina@arm.com>
 
 	PR target/84711
+	* config/arm/arm.c (arm_can_change_mode_class): Use GET_MODE_UNIT_SIZE
+	instead of GET_MODE_SIZE when comparing Units.
+
+2018-07-05  Tamar Christina  <tamar.christina@arm.com>
+
+	PR target/84711
 	* rtlanal.c (set_noop_p): Constrain on mode change,
 	include hard-reg-set.h
 

gcc/config/arm/arm.c

@@ -31512,8 +31512,8 @@ arm_can_change_mode_class (machine_mode from, machine_mode to,
 {
   if (TARGET_BIG_END
       && !(GET_MODE_SIZE (from) == 16 && GET_MODE_SIZE (to) == 8)
-      && (GET_MODE_SIZE (from) > UNITS_PER_WORD
-	  || GET_MODE_SIZE (to) > UNITS_PER_WORD)
+      && (GET_MODE_UNIT_SIZE (from) > UNITS_PER_WORD
+	  || GET_MODE_UNIT_SIZE (to) > UNITS_PER_WORD)
       && reg_classes_intersect_p (VFP_REGS, rclass))
     return false;
   return true;

gcc/testsuite/ChangeLog

 2018-07-05  Tamar Christina  <tamar.christina@arm.com>
 
 	PR target/84711
+	* gcc.target/arm/big-endian-subreg.c: New.
+
+2018-07-05  Tamar Christina  <tamar.christina@arm.com>
+
+	PR target/84711
 	* gcc.dg/vect/pr84711.c: New.
 
 2018-07-05  Tamar Christina  <tamar.christina@arm.com>

gcc/testsuite/gcc.target/arm/big-endian-subreg.c

+/* { dg-do compile } */
+/* { dg-require-effective-target arm_neon_ok } */
+/* { dg-require-effective-target arm_hf_eabi } */
+/* { dg-add-options arm_neon } */
+/* { dg-additional-options "-mfp16-format=ieee -mfloat-abi=hard" } */
+
+typedef __fp16 v4f16
+  __attribute__ ((vector_size (8)));
+
+v4f16 fn1 (v4f16 p)
+{
+  return p;
+}