[LRA] PR70904, relax the restriction on subreg reload for wide mode

2016-05-12  Jiong Wang  <jiong.wang@arm.com>

gcc/
  PR rtl-optimization/70904
  * lra-constraint.c (process_addr_reg): Relax the restriction on
  subreg reload for wide mode.

From-SVN: r236181

gcc/ChangeLog

+2016-05-12  Jiong Wang  <jiong.wang@arm.com>
+
+	PR rtl-optimization/70904
+	* lra-constraint.c (process_addr_reg): Relax the restriction on subreg
+	reload for wide mode.
+
 2016-05-12  Marek Polacek  <polacek@redhat.com>
 
 	PR c/70756

gcc/lra-constraints.c

@@ -1307,7 +1307,21 @@ process_addr_reg (rtx *loc, bool check_only_p, rtx_insn **before, rtx_insn **aft
 
   subreg_p = GET_CODE (*loc) == SUBREG;
   if (subreg_p)
-    loc = &SUBREG_REG (*loc);
+    {
+      reg = SUBREG_REG (*loc);
+      mode = GET_MODE (reg);
+
+      /* For mode with size bigger than ptr_mode, there unlikely to be "mov"
+	 between two registers with different classes, but there normally will
+	 be "mov" which transfers element of vector register into the general
+	 register, and this normally will be a subreg which should be reloaded
+	 as a whole.  This is particularly likely to be triggered when
+	 -fno-split-wide-types specified.  */
+      if (in_class_p (reg, cl, &new_class)
+	  || GET_MODE_SIZE (mode) <= GET_MODE_SIZE (ptr_mode))
+       loc = &SUBREG_REG (*loc);
+    }
+
   reg = *loc;
   mode = GET_MODE (reg);
   if (! REG_P (reg))