* config/h8300/h8300.md (a peephole2): New.

From-SVN: r62792

gcc/ChangeLog

+2003-02-12  Kazu Hirata  <kazu@cs.umass.edu>
+
+	* config/h8300/h8300.md (a peephole2): New.
+
 Wed Feb 12 22:47:18 CET 2003  Jan Hubicka  <jh@suse.cz>
 
 	* Makefile.in (CRTSTUFF_CFLAGS): Add -fno-unit-at-a-time

gcc/config/h8300/h8300.md

@@ -3561,6 +3561,36 @@
 		  gen_rtx_NE (VOIDmode, cc0_rtx, const0_rtx) :
 		  gen_rtx_EQ (VOIDmode, cc0_rtx, const0_rtx));")
 
+;; For constants like -1, -2, 1, 2, it is still cheaper to make a copy
+;; of the register being tested, do the subtraction on the copy, and
+;; then test the copy.  We avoid this transformation if we see more
+;; than one copy of the same compare insn.
+
+(define_peephole2
+  [(match_scratch:SI 4 "r")
+   (set (cc0)
+	(compare:SI (match_operand:SI 0 "register_operand" "")
+		    (match_operand:SI 1 "incdec_operand" "")))
+   (set (pc)
+	(if_then_else (match_operator 3 "eqne_operator"
+			[(cc0) (const_int 0)])
+		      (label_ref (match_operand 2 "" ""))
+		      (pc)))]
+  "(TARGET_H8300H || TARGET_H8300S)
+   && !peep2_reg_dead_p (1, operands[0])
+   && !rtx_equal_p (PATTERN (insn),
+		    PATTERN (next_nonnote_insn (next_nonnote_insn (insn))))"
+  [(set (cc0)
+	(match_dup 0))
+   (set (pc)
+	(if_then_else (match_op_dup 3 [(cc0) (const_int 0)])
+		      (label_ref (match_dup 2))
+		      (pc)))]
+  "emit_move_insn (operands[4], operands[0]);
+   operands[0] = operands[4];
+   operands[1] = GEN_INT (- INTVAL (operands[1]));
+   split_adds_subs (SImode, operands, 1);")
+
 ;; Narrow the mode of testing if possible.
 
 (define_peephole2