sh.md: Add new unnamed split pattern to handle movt-movt sequences.

gcc/
	* config/sh/sh.md: Add new unnamed split pattern to handle movt-movt
	sequences.

From-SVN: r228386

gcc/ChangeLog

+2015-10-02  Oleg Endo  <olegendo@gcc.gnu.org>
+
+	* config/sh/sh.md: Add new unnamed split pattern to handle movt-movt
+	sequences.
+
 2015-10-02  Renlin Li  <renlin.li@arm.com>
 
 	PR target/66776

gcc/config/sh/sh.md

@@ -14860,6 +14860,46 @@ label:
 			  gen_rtx_REG (SImode, (REGNO (operands[1])))));
 })
 
+;; This is not a peephole, but it's here because it's actually supposed
+;; to be one.  It tries to convert a sequence such as
+;;	movt	r2	->	movt	r2
+;;	movt	r13		mov	r2,r13
+;; This gives the schduler a bit more freedom to hoist a following
+;; comparison insn.  Moreover, it the reg-reg mov insn is MT group which has
+;; better chances for parallel execution.
+;; We can do this with a peephole2 pattern, but then the cprop_hardreg
+;; pass will revert the change.  See also PR 64331.
+;; Thus do it manually in one of the split passes after register allocation.
+;; Sometimes the cprop_hardreg pass might also eliminate the reg-reg copy.
+(define_split
+  [(set (match_operand:SI 0 "arith_reg_dest")
+	(match_operand:SI 1 "t_reg_operand"))]
+  "TARGET_SH1 && reload_completed"
+  [(set (match_dup 0) (match_dup 1))]
+{
+  rtx t_reg = get_t_reg_rtx ();
+
+  for (rtx_insn* i = prev_nonnote_insn_bb (curr_insn); i != NULL;
+       i = prev_nonnote_insn_bb (i))
+    {
+      if (!INSN_P (i) || DEBUG_INSN_P (i))
+	continue;
+
+      if (modified_in_p (t_reg, i) || BARRIER_P (i))
+	FAIL;
+
+      if (sh_is_movt_insn (i))
+	{
+	  rtx r = sh_movt_set_dest (i);
+	  if (!modified_between_p (r, i, curr_insn))
+	    {
+	      operands[1] = r;
+	      break;
+	   }
+	}
+    }
+})
+
 (define_peephole
   [(set (match_operand:SI 0 "register_operand" "=r")
 	(plus:SI (match_dup 0) (match_operand:SI 1 "register_operand" "r")))