diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index ef606f33983..50de6a83cba 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -1136,6 +1136,12 @@ riscv_const_insns (rtx x)
     case LABEL_REF:
       return riscv_symbol_insns (riscv_classify_symbol (x));
 
+    /* TODO: In RVV, we get CONST_POLY_INT by using csrr vlenb
+       instruction and several scalar shift or mult instructions,
+       it is so far unknown. We set it to 4 temporarily.  */
+    case CONST_POLY_INT:
+      return 4;
+
     default:
       return 0;
     }
@@ -2507,6 +2513,13 @@ riscv_output_move (rtx dest, rtx src)
 	    return "fld\t%0,%1";
 	  }
     }
+  if (dest_code == REG && GP_REG_P (REGNO (dest)) && src_code == CONST_POLY_INT)
+    {
+      /* we only want a single full vector register vlen
+	 read after reload. */
+      gcc_assert (known_eq (rtx_to_poly_int64 (src), BYTES_PER_RISCV_VECTOR));
+      return "csrr\t%0,vlenb";
+    }
   gcc_unreachable ();
 }
 
diff --git a/gcc/config/riscv/riscv.md b/gcc/config/riscv/riscv.md
index 63bb3c8debc..2bfab198370 100644
--- a/gcc/config/riscv/riscv.md
+++ b/gcc/config/riscv/riscv.md
@@ -148,7 +148,7 @@
 ;; scheduling type to be "multi" instead.
 (define_attr "move_type"
   "unknown,load,fpload,store,fpstore,mtc,mfc,move,fmove,
-   const,logical,arith,andi,shift_shift"
+   const,logical,arith,andi,shift_shift,rdvlenb"
   (const_string "unknown"))
 
 ;; Main data type used by the insn
@@ -166,6 +166,35 @@
 	 (const_string "yes")]
 	(const_string "no")))
 
+;; ISA attributes.
+(define_attr "ext" "base,f,d,vector"
+  (const_string "base"))
+
+;; True if the extension is enabled.
+(define_attr "ext_enabled" "no,yes"
+  (cond [(eq_attr "ext" "base")
+	 (const_string "yes")
+	
+	 (and (eq_attr "ext" "f")
+	      (match_test "TARGET_HARD_FLOAT"))
+	 (const_string "yes")
+
+	 (and (eq_attr "ext" "d")
+	      (match_test "TARGET_DOUBLE_FLOAT"))
+	 (const_string "yes")
+
+	 (and (eq_attr "ext" "vector")
+	      (match_test "TARGET_VECTOR"))
+	 (const_string "yes")
+	]
+	(const_string "no")))
+
+;; Attribute to control enable or disable instructions.
+(define_attr "enabled" "no,yes"
+  (cond [(eq_attr "ext_enabled" "no")
+	 (const_string "no")]
+	(const_string "yes")))
+
 ;; Classification of each insn.
 ;; branch	conditional branch
 ;; jump		unconditional jump
@@ -326,7 +355,8 @@
 	      (eq_attr "dword_mode" "yes"))
 	   (const_string "multi")
 	 (eq_attr "move_type" "move") (const_string "move")
-	 (eq_attr "move_type" "const") (const_string "const")]
+	 (eq_attr "move_type" "const") (const_string "const")
+	 (eq_attr "move_type" "rdvlenb") (const_string "rdvlenb")]
 	(const_string "unknown")))
 
 ;; Length of instruction in bytes.
@@ -1633,24 +1663,26 @@
 })
 
 (define_insn "*movdi_32bit"
-  [(set (match_operand:DI 0 "nonimmediate_operand" "=r,r,r,m,  *f,*f,*r,*f,*m")
-	(match_operand:DI 1 "move_operand"         " r,i,m,r,*J*r,*m,*f,*f,*f"))]
+  [(set (match_operand:DI 0 "nonimmediate_operand" "=r,r,r,m,  *f,*f,*r,*f,*m,r")
+	(match_operand:DI 1 "move_operand"         " r,i,m,r,*J*r,*m,*f,*f,*f,vp"))]
   "!TARGET_64BIT
    && (register_operand (operands[0], DImode)
        || reg_or_0_operand (operands[1], DImode))"
   { return riscv_output_move (operands[0], operands[1]); }
-  [(set_attr "move_type" "move,const,load,store,mtc,fpload,mfc,fmove,fpstore")
-   (set_attr "mode" "DI")])
+  [(set_attr "move_type" "move,const,load,store,mtc,fpload,mfc,fmove,fpstore,rdvlenb")
+   (set_attr "mode" "DI")
+   (set_attr "ext" "base,base,base,base,d,d,d,d,d,vector")])
 
 (define_insn "*movdi_64bit"
-  [(set (match_operand:DI 0 "nonimmediate_operand" "=r,r,r, m,  *f,*f,*r,*f,*m")
-	(match_operand:DI 1 "move_operand"         " r,T,m,rJ,*r*J,*m,*f,*f,*f"))]
+  [(set (match_operand:DI 0 "nonimmediate_operand" "=r,r,r, m,  *f,*f,*r,*f,*m,r")
+	(match_operand:DI 1 "move_operand"         " r,T,m,rJ,*r*J,*m,*f,*f,*f,vp"))]
   "TARGET_64BIT
    && (register_operand (operands[0], DImode)
        || reg_or_0_operand (operands[1], DImode))"
   { return riscv_output_move (operands[0], operands[1]); }
-  [(set_attr "move_type" "move,const,load,store,mtc,fpload,mfc,fmove,fpstore")
-   (set_attr "mode" "DI")])
+  [(set_attr "move_type" "move,const,load,store,mtc,fpload,mfc,fmove,fpstore,rdvlenb")
+   (set_attr "mode" "DI")
+   (set_attr "ext" "base,base,base,base,d,d,d,d,d,vector")])
 
 ;; 32-bit Integer moves
 
@@ -1664,13 +1696,14 @@
 })
 
 (define_insn "*movsi_internal"
-  [(set (match_operand:SI 0 "nonimmediate_operand" "=r,r,r, m,  *f,*f,*r,*m")
-	(match_operand:SI 1 "move_operand"         " r,T,m,rJ,*r*J,*m,*f,*f"))]
+  [(set (match_operand:SI 0 "nonimmediate_operand" "=r,r,r, m,  *f,*f,*r,*m,r")
+	(match_operand:SI 1 "move_operand"         " r,T,m,rJ,*r*J,*m,*f,*f,vp"))]
   "(register_operand (operands[0], SImode)
     || reg_or_0_operand (operands[1], SImode))"
   { return riscv_output_move (operands[0], operands[1]); }
-  [(set_attr "move_type" "move,const,load,store,mtc,fpload,mfc,fpstore")
-   (set_attr "mode" "SI")])
+  [(set_attr "move_type" "move,const,load,store,mtc,fpload,mfc,fpstore,rdvlenb")
+   (set_attr "mode" "SI")
+   (set_attr "ext" "base,base,base,base,f,f,f,f,vector")])
 
 ;; 16-bit Integer moves
 
@@ -1689,13 +1722,14 @@
 })
 
 (define_insn "*movhi_internal"
-  [(set (match_operand:HI 0 "nonimmediate_operand" "=r,r,r, m,  *f,*r")
-	(match_operand:HI 1 "move_operand"	   " r,T,m,rJ,*r*J,*f"))]
+  [(set (match_operand:HI 0 "nonimmediate_operand" "=r,r,r, m,  *f,*r,r")
+	(match_operand:HI 1 "move_operand"	   " r,T,m,rJ,*r*J,*f,vp"))]
   "(register_operand (operands[0], HImode)
     || reg_or_0_operand (operands[1], HImode))"
   { return riscv_output_move (operands[0], operands[1]); }
-  [(set_attr "move_type" "move,const,load,store,mtc,mfc")
-   (set_attr "mode" "HI")])
+  [(set_attr "move_type" "move,const,load,store,mtc,mfc,rdvlenb")
+   (set_attr "mode" "HI")
+   (set_attr "ext" "base,base,base,base,f,f,vector")])
 
 ;; HImode constant generation; see riscv_move_integer for details.
 ;; si+si->hi without truncation is legal because of
@@ -1731,13 +1765,14 @@
 })
 
 (define_insn "*movqi_internal"
-  [(set (match_operand:QI 0 "nonimmediate_operand" "=r,r,r, m,  *f,*r")
-	(match_operand:QI 1 "move_operand"         " r,I,m,rJ,*r*J,*f"))]
+  [(set (match_operand:QI 0 "nonimmediate_operand" "=r,r,r, m,  *f,*r,r")
+	(match_operand:QI 1 "move_operand"         " r,I,m,rJ,*r*J,*f,vp"))]
   "(register_operand (operands[0], QImode)
     || reg_or_0_operand (operands[1], QImode))"
   { return riscv_output_move (operands[0], operands[1]); }
-  [(set_attr "move_type" "move,const,load,store,mtc,mfc")
-   (set_attr "mode" "QI")])
+  [(set_attr "move_type" "move,const,load,store,mtc,mfc,rdvlenb")
+   (set_attr "mode" "QI")
+   (set_attr "ext" "base,base,base,base,f,f,vector")])
 
 ;; 32-bit floating point moves
 
