h8300.md (*zero_extendqihi2_h8300): Make the second alternative "#".

	* config/h8300/h8300.md (*zero_extendqihi2_h8300): Make the
	second alternative "#".
	(*zero_extendqihi2_h8300hs): Likewise.
	(a define_split): New.

From-SVN: r60388

gcc/ChangeLog

 2002-12-21  Kazu Hirata  <kazu@cs.umass.edu>
 
+	* config/h8300/h8300.md (*zero_extendqihi2_h8300): Make the
+	second alternative "#".
+	(*zero_extendqihi2_h8300hs): Likewise.
+	(a define_split): New.
+
+2002-12-21  Kazu Hirata  <kazu@cs.umass.edu>
+
 	* config/h8300/h8300-protos.h: Update the prototype for
 	split_adds_subs.
 	Add prototypes for const_le_2_operand and const_le_6_operand.

gcc/config/h8300/h8300.md

@@ -1802,26 +1802,41 @@
   ""
   "")
 
-(define_insn ""
+(define_insn "*zero_extendqihi2_h8300"
   [(set (match_operand:HI 0 "register_operand" "=r,r")
 	(zero_extend:HI (match_operand:QI 1 "general_operand_src" "0,g>")))]
   "TARGET_H8300"
   "@
   mov.b	#0,%t0
-  mov.b	%R1,%s0\;mov.b	#0,%t0"
+  #"
   [(set_attr "length" "2,10")
    (set_attr "cc" "clobber,clobber")])
 
-(define_insn ""
+(define_insn "*zero_extendqihi2_h8300hs"
   [(set (match_operand:HI 0 "register_operand" "=r,r")
 	(zero_extend:HI (match_operand:QI 1 "general_operand_src" "0,g>")))]
   "TARGET_H8300H || TARGET_H8300S"
   "@
   extu.w	%T0
-  mov.b	%R1,%s0\;extu.w	%T0"
+  #"
   [(set_attr "length" "2,10")
    (set_attr "cc" "set_znv,set_znv")])
 
+;; Split the zero extension of a general operand (actually a memory
+;; operand) into a load of the operand and the actual zero extension
+;; so that 1) the length will be accurate, and 2) the zero extensions
+;; appearing at the end of basic blocks may be merged.
+
+(define_split
+  [(set (match_operand:HI 0 "register_operand" "")
+	(zero_extend:HI (match_operand:QI 1 "general_operand_src" "")))]
+  "reload_completed"
+  [(set (match_dup 2)
+	(match_dup 1))
+   (set (match_dup 0)
+	(zero_extend:HI (match_dup 2)))]
+  "operands[2] = gen_rtx_REG (QImode, REGNO (operands[0]));")
+
 ;; The compiler can synthesize a H8/300H variant of this which is
 ;; just as efficient as one that we'd create
 (define_insn "zero_extendqisi2"