Revert "Clean up mode iterator in riscv.md"

GCC no longer builds for with this patch.  pic.md uses SUBX.

This reverts commit dd5108c.

gcc/config/riscv/riscv.md

@@ -244,6 +244,9 @@
 ;; QImode values so we can force zero-extension.
 (define_mode_iterator BR [(QI "TARGET_64BIT") SI (DI "TARGET_64BIT")])
 
+;; 32-bit moves for which we provide move patterns.
+(define_mode_iterator MOVE32 [SI])
+
 ;; 64-bit modes for which we provide move patterns.
 (define_mode_iterator MOVE64 [DI DF])
 
@@ -256,6 +259,9 @@
 ;; Iterator for QImode extension patterns.
 (define_mode_iterator SUPERQI [HI SI (DI "TARGET_64BIT")])
 
+;; Iterator for hardware integer modes narrower than XLEN.
+(define_mode_iterator SUBX [QI HI (SI "TARGET_64BIT")])
+
 ;; Iterator for hardware-supported integer modes.
 (define_mode_iterator ANYI [QI HI SI (DI "TARGET_64BIT")])
 
@@ -1258,8 +1264,8 @@
 ;; 32-bit Integer moves
 
 (define_expand "mov<mode>"
-  [(set (match_operand:SI 0 "")
-	(match_operand:SI 1 ""))]
+  [(set (match_operand:MOVE32 0 "")
+	(match_operand:MOVE32 1 ""))]
   ""
 {
   if (riscv_legitimize_move (<MODE>mode, operands[0], operands[1]))