diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 425e6ce2c78..d99ef4affcb 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,13 @@
+Wed Apr  4 00:45:38 EDT 2001  John Wehle  (john@feith.com)
+
+	* rtl.h (set_noop_p): Declare.
+	* flow.c (set_noop_p): Move from here ...
+	* rtlanal.c (set_noop_p): ... to here and enhance.
+	* cse.c (delete_trivially_dead_insns): Use it.
+	* gcse.c (hash_scan_set): Likewise.
+	* jump.c (delete_noop_moves): Likewise.
+	* recog.c (split_all_insns): Likewise.
+
 2001-04-04  Alan Modra  <alan@linuxcare.com.au>
 
 	* dwarf2out.c (dwarf2out_frame_debug_expr): Support adjusting
diff --git a/gcc/cse.c b/gcc/cse.c
index 2b487510eae..6913aef32b5 100644
--- a/gcc/cse.c
+++ b/gcc/cse.c
@@ -7612,14 +7612,7 @@ delete_trivially_dead_insns (insns, nreg)
 	live_insn = ! dead_libcall;
       else if (GET_CODE (PATTERN (insn)) == SET)
 	{
-	  if ((GET_CODE (SET_DEST (PATTERN (insn))) == REG
-	       || GET_CODE (SET_DEST (PATTERN (insn))) == SUBREG)
-	      && rtx_equal_p (SET_DEST (PATTERN (insn)),
-			      SET_SRC (PATTERN (insn))))
-	    ;
-	  else if (GET_CODE (SET_DEST (PATTERN (insn))) == STRICT_LOW_PART
-		   && rtx_equal_p (XEXP (SET_DEST (PATTERN (insn)), 0),
-				   SET_SRC (PATTERN (insn))))
+	  if (set_noop_p (PATTERN (insn)))
 	    ;
 
 #ifdef HAVE_cc0
@@ -7649,9 +7642,7 @@ delete_trivially_dead_insns (insns, nreg)
 
 	    if (GET_CODE (elt) == SET)
 	      {
-		if ((GET_CODE (SET_DEST (elt)) == REG
-		     || GET_CODE (SET_DEST (elt)) == SUBREG)
-		    && rtx_equal_p (SET_DEST (elt), SET_SRC (elt)))
+		if (set_noop_p (elt))
 		  ;
 
 #ifdef HAVE_cc0
diff --git a/gcc/flow.c b/gcc/flow.c
index 388bd2a9d8a..607ecb6a115 100644
--- a/gcc/flow.c
+++ b/gcc/flow.c
@@ -386,7 +386,6 @@ static void tidy_fallthru_edges		PARAMS ((void));
 static int verify_wide_reg_1		PARAMS ((rtx *, void *));
 static void verify_wide_reg		PARAMS ((int, rtx, rtx));
 static void verify_local_live_at_start	PARAMS ((regset, basic_block));
-static int set_noop_p			PARAMS ((rtx));
 static int noop_move_p			PARAMS ((rtx));
 static void delete_noop_moves		PARAMS ((rtx));
 static void notice_stack_pointer_modification_1 PARAMS ((rtx, rtx, void *));
@@ -3077,27 +3076,6 @@ free_basic_block_vars (keep_head_end_p)
     }
 }
 
-/* Return nonzero if the destination of SET equals the source.  */
-
-static int
-set_noop_p (set)
-     rtx set;
-{
-  rtx src = SET_SRC (set);
-  rtx dst = SET_DEST (set);
-
-  if (GET_CODE (src) == SUBREG && GET_CODE (dst) == SUBREG)
-    {
-      if (SUBREG_BYTE (src) != SUBREG_BYTE (dst))
-	return 0;
-      src = SUBREG_REG (src);
-      dst = SUBREG_REG (dst);
-    }
-
-  return (GET_CODE (src) == REG && GET_CODE (dst) == REG
-	  && REGNO (src) == REGNO (dst));
-}
-
 /* Return nonzero if an insn consists only of SETs, each of which only sets a
    value to itself.  */
 
diff --git a/gcc/gcse.c b/gcc/gcse.c
index cac80f9d4b9..9eda522e859 100644
--- a/gcc/gcse.c
+++ b/gcc/gcse.c
@@ -1964,7 +1964,7 @@ hash_scan_set (pat, insn, set_p)
 	  /* Is SET_SRC something we want to gcse?  */
 	  && want_to_gcse_p (src)
 	  /* Don't CSE a nop.  */
-	  && src != dest)
+	  && ! set_noop_p (pat))
 	{
 	  /* An expression is not anticipatable if its operands are
 	     modified before this insn or if this is not the only SET in
diff --git a/gcc/jump.c b/gcc/jump.c
index 5c5807394dc..6bd6edd9c48 100644
--- a/gcc/jump.c
+++ b/gcc/jump.c
@@ -956,15 +956,7 @@ delete_noop_moves (f)
 	  /* Detect and delete no-op move instructions
 	     resulting from not allocating a parameter in a register.  */
 
-	  if (GET_CODE (body) == SET
-	      && (SET_DEST (body) == SET_SRC (body)
-		  || (GET_CODE (SET_DEST (body)) == MEM
-		      && GET_CODE (SET_SRC (body)) == MEM
-		      && rtx_equal_p (SET_SRC (body), SET_DEST (body))))
-	      && ! (GET_CODE (SET_DEST (body)) == MEM
-		    && MEM_VOLATILE_P (SET_DEST (body)))
-	      && ! (GET_CODE (SET_SRC (body)) == MEM
-		    && MEM_VOLATILE_P (SET_SRC (body))))
+	  if (GET_CODE (body) == SET && set_noop_p (body))
 	    delete_computation (insn);
 
 	  /* Detect and ignore no-op move instructions
@@ -1073,16 +1065,6 @@ delete_noop_moves (f)
 	      if (i < 0)
 		delete_insn (insn);
 	    }
-	  /* Also delete insns to store bit fields if they are no-ops.  */
-	  /* Not worth the hair to detect this in the big-endian case.  */
-	  else if (! BYTES_BIG_ENDIAN
-		   && GET_CODE (body) == SET
-		   && GET_CODE (SET_DEST (body)) == ZERO_EXTRACT
-		   && XEXP (SET_DEST (body), 2) == const0_rtx
-		   && XEXP (SET_DEST (body), 0) == SET_SRC (body)
-		   && ! (GET_CODE (SET_SRC (body)) == MEM
-			 && MEM_VOLATILE_P (SET_SRC (body))))
-	    delete_insn (insn);
 	}
       insn = next;
     }
diff --git a/gcc/recog.c b/gcc/recog.c
index e278f985529..bc7c712de24 100644
--- a/gcc/recog.c
+++ b/gcc/recog.c
@@ -2882,7 +2882,7 @@ split_all_insns (upd_life)
 	     break the code that handles REG_NO_CONFLICT blocks.  */
 
 	  else if ((set = single_set (insn)) != NULL
-		   && rtx_equal_p (SET_SRC (set), SET_DEST (set)))
+		   && set_noop_p (set))
 	    {
 	      /* Nops get in the way while scheduling, so delete them
 		 now if register allocation has already been done.  It
diff --git a/gcc/rtl.h b/gcc/rtl.h
index 667a304aec3..02f37b75018 100644
--- a/gcc/rtl.h
+++ b/gcc/rtl.h
@@ -1401,6 +1401,7 @@ extern int insn_dependent_p		PARAMS ((rtx, rtx));
 extern int reg_set_p			PARAMS ((rtx, rtx));
 extern rtx single_set_2			PARAMS ((rtx, rtx));
 extern int multiple_sets		PARAMS ((rtx));
+extern int set_noop_p			PARAMS ((rtx));
 extern rtx find_last_value		PARAMS ((rtx, rtx *, rtx, int));
 extern int refers_to_regno_p		PARAMS ((unsigned int, unsigned int,
 						 rtx, rtx *));
diff --git a/gcc/rtlanal.c b/gcc/rtlanal.c
index 36c3c9ff42f..3dd7c138b0d 100644
--- a/gcc/rtlanal.c
+++ b/gcc/rtlanal.c
@@ -980,6 +980,42 @@ multiple_sets (insn)
   return 0;
 }
 
+/* Return nonzero if the destination of SET equals the source
+   and there are no side effects.  */
+
+int
+set_noop_p (set)
+     rtx set;
+{
+  rtx src = SET_SRC (set);
+  rtx dst = SET_DEST (set);
+
+  if (side_effects_p (src) || side_effects_p (dst))
+    return 0;
+
+  if (GET_CODE (dst) == MEM && GET_CODE (src) == MEM)
+    return rtx_equal_p (dst, src);
+
+  if (GET_CODE (dst) == SIGN_EXTRACT
+      || GET_CODE (dst) == ZERO_EXTRACT)
+    return rtx_equal_p (XEXP (dst, 0), src)
+	   && ! BYTES_BIG_ENDIAN && XEXP (dst, 2) == const0_rtx;
+
+  if (GET_CODE (dst) == STRICT_LOW_PART)
+    dst = XEXP (dst, 0);
+
+  if (GET_CODE (src) == SUBREG && GET_CODE (dst) == SUBREG)
+    {
+      if (SUBREG_BYTE (src) != SUBREG_BYTE (dst))
+	return 0;
+      src = SUBREG_REG (src);
+      dst = SUBREG_REG (dst);
+    }
+
+  return (GET_CODE (src) == REG && GET_CODE (dst) == REG
+	  && REGNO (src) == REGNO (dst));
+}
+
 /* Return the last thing that X was assigned from before *PINSN.  If VALID_TO
    is not NULL_RTX then verify that the object is not modified up to VALID_TO.
    If the object was modified, if we hit a partial assignment to X, or hit a