diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index d5c28ee1066..a34ad21c540 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,14 @@
+2008-08-09  Andy Hutchinson  <hutchinsonandy@aim.com>
+
+	PR target/36609
+	* config/avr/avr.c (avr_reorg): Create RTL for reversed compare with
+	zero.
+	* config/avr/avr.md  (QISI) : Define mode iterator.
+	(negated_tst<mode>) : Redefine as split using mode macro.
+	(reversed_tstqi): Define insn as reversed compare with zero.
+	(reversed_tsthi): Ditto.
+	(reversed_tstsi): Ditto.
+
 2008-09-08  Jakub Jelinek  <jakub@redhat.com>
 
 	PR middle-end/37393
diff --git a/gcc/config/avr/avr.c b/gcc/config/avr/avr.c
index cc8b65cae7d..fb217bb167a 100644
--- a/gcc/config/avr/avr.c
+++ b/gcc/config/avr/avr.c
@@ -5683,7 +5683,7 @@ avr_reorg (void)
 	      rtx t = XEXP (src,0);
 
 	      PUT_CODE (t, swap_condition (GET_CODE (t)));
-	      SET_SRC (pattern) = gen_rtx_NEG (GET_MODE (SET_SRC (pattern)),
+	      SET_SRC (pattern) = gen_rtx_COMPARE (GET_MODE (SET_SRC (pattern)), const0_rtx,
 					       SET_SRC (pattern));
 	      INSN_CODE (next) = -1;
 	      INSN_CODE (insn) = -1;
diff --git a/gcc/config/avr/avr.md b/gcc/config/avr/avr.md
index 371ca76c7dd..8dad9d8fe80 100644
--- a/gcc/config/avr/avr.md
+++ b/gcc/config/avr/avr.md
@@ -117,6 +117,9 @@
 		       (const_int 2))]
         (const_int 2)))
 
+;; Define mode iterator
+(define_mode_iterator QISI [(QI "") (HI "") (SI "")])
+
 ;;========================================================================
 ;; The following is used by nonlocal_goto and setjmp.
 ;; The receiver pattern will create no instructions since internally
@@ -2015,9 +2018,10 @@
   [(set_attr "cc" "compare")
    (set_attr "length" "1")])
 
-(define_insn "*negated_tstqi"
+(define_insn "*reversed_tstqi"
   [(set (cc0)
-        (neg:QI (match_operand:QI 0 "register_operand" "r")))]
+        (compare (const_int 0)  
+		 (match_operand:QI 0 "register_operand" "r")))]
   ""
   "cp __zero_reg__,%0"
   [(set_attr "cc" "compare")
@@ -2031,9 +2035,10 @@
 [(set_attr "cc" "compare,compare")
  (set_attr "length" "1,2")])
 
-(define_insn "*negated_tsthi"
+(define_insn "*reversed_tsthi"
   [(set (cc0)
-        (neg:HI (match_operand:HI 0 "register_operand" "r")))]
+        (compare (const_int 0)
+		 (match_operand:HI 0 "register_operand" "r")))]
   ""
   "cp __zero_reg__,%A0
 	cpc __zero_reg__,%B0"
@@ -2048,9 +2053,10 @@
   [(set_attr "cc" "compare")
    (set_attr "length" "4")])
 
-(define_insn "*negated_tstsi"
+(define_insn "*reversed_tstsi"
   [(set (cc0)
-        (neg:SI (match_operand:SI 0 "register_operand" "r")))]
+        (compare (const_int 0)  
+		 (match_operand:SI 0 "register_operand" "r")))]
   ""
   "cp __zero_reg__,%A0
 	cpc __zero_reg__,%B0
@@ -2187,6 +2193,19 @@
   [(set_attr "cc" "compare,compare,compare,compare,compare")
    (set_attr "length" "4,4,7,5,8")])
 
+; Optimize negated tests into reverse compare if overflow is undefined.
+(define_insn_and_split "negated_tst<mode>"
+ [(set (cc0)
+        (neg:QISI (match_operand:QISI 0 "register_operand")))]
+
+  "(!flag_wrapv && !flag_trapv && flag_strict_overflow)"
+  "#"
+  ""
+  [(set (cc0)
+        (compare (const_int 0)  
+		 (match_dup 0)))]
+  "")
+
 ;; ----------------------------------------------------------------------
 ;; JUMP INSTRUCTIONS
 ;; ----------------------------------------------------------------------