diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index b5afd17404e..24d534b4d0d 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2004-12-16  Richard Henderson  <rth@redhat.com>
+	    Aldy Hernandez  <aldyh@redhat.com>
+
+	* simplify-rtx.c (simplify_replace_rtx): Do not blindly replace
+	hard registers.
+
 2004-12-16  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR other/18508
diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c
index 3685bbf8d2c..5feeb650dc9 100644
--- a/gcc/simplify-rtx.c
+++ b/gcc/simplify-rtx.c
@@ -337,7 +337,7 @@ simplify_replace_rtx (rtx x, rtx old_rtx, rtx new_rtx)
 	}
       else if (code == REG)
 	{
-	  if (REG_P (old_rtx) && REGNO (x) == REGNO (old_rtx))
+	  if (rtx_equal_p (x, old_rtx))
 	    return new_rtx;
 	}
       break;