combine.c (simplify_comparison): Reduce (OP (MINUS A B) 0) to (OP A B).

        * combine.c (simplify_comparison): Reduce (OP (MINUS A B) 0)
        to (OP A B).

From-SVN: r30970

gcc/ChangeLog

+Thu Dec 16 02:41:26 1999  Richard Henderson (rth@cygnus.com)
+
+	* combine.c (simplify_comparison): Reduce (OP (MINUS A B) 0)
+	to (OP A B).
+
 Thu Dec 16 02:26:11 1999  Jeffrey A Law  (law@cygnus.com)
 
 	* h8300.md (HImode preinc peephole): Fix typo.

gcc/combine.c

@@ -10320,6 +10320,14 @@ simplify_comparison (code, pop0, pop1)
 	  break;
 
 	case MINUS:
+	  /* (op (minus A B) 0) -> (op A B) */
+	  if (op1 == const0_rtx)
+	    {
+	      op1 = XEXP (op0, 1);
+	      op0 = XEXP (op0, 0);
+	      continue;
+	    }
+
 	  /* (eq (minus A B) C) -> (eq A (plus B C)) or
 	     (eq B (minus A C)), whichever simplifies.  We can only do
 	     this for equality comparisons due to pathological cases involving