(decrement_and_branch_until_zero): Use arithmetic_comparison_operator to decide...

(decrement_and_branch_until_zero): Use arithmetic_comparison_operator
to decide if there is comparison suitable to be expressed by condition
code from an arithmetic op.

From-SVN: r10269

gcc/config/i386/i386.md

@@ -4910,6 +4910,9 @@
   return AS1 (jmp,%*%0);
 }")
 
+;; ??? could transform while(--i > 0) S; to if (--i > 0) do S; while(--i);
+;;     if S does not change i
+
 (define_expand "decrement_and_branch_until_zero"
   [(parallel [(set (pc)
 		   (if_then_else (ge (plus:SI (match_operand:SI 0 "general_operand" "")
@@ -4925,7 +4928,7 @@
 
 (define_insn ""
   [(set (pc)
-	(if_then_else (match_operator 0 "comparison_operator"
+	(if_then_else (match_operator 0 "arithmetic_comparison_operator"
 				      [(plus:SI (match_operand:SI 1 "general_operand" "+r,m")
 						(match_operand:SI 2 "general_operand" "rmi,ri"))
 				       (const_int 0)])
@@ -4952,7 +4955,7 @@
 
 (define_insn ""
   [(set (pc)
-	(if_then_else (match_operator 0 "comparison_operator"
+	(if_then_else (match_operator 0 "arithmetic_comparison_operator"
 				      [(minus:SI (match_operand:SI 1 "general_operand" "+r,m")
 						 (match_operand:SI 2 "general_operand" "rmi,ri"))
 				       (const_int 0)])