diff --git a/model/riscv_insts_vext_arith.sail b/model/riscv_insts_vext_arith.sail
index 68a986b3a..915a9fdfa 100644
--- a/model/riscv_insts_vext_arith.sail
+++ b/model/riscv_insts_vext_arith.sail
@@ -80,7 +80,7 @@ function clause execute(VVTYPE(funct6, vm, vs2, vs1, vd)) = {
   let VLEN_pow = get_vlen_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) | not(valid_rd_mask(vd, vm)) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_normal(vd, vm) then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -214,7 +214,7 @@ function clause execute(NVSTYPE(funct6, vm, vs2, vs1, vd)) = {
   let SEW_widen      = SEW * 2;
   let LMUL_pow_widen = LMUL_pow + 1;
 
-  if  not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_eew_emul(SEW_widen, LMUL_pow_widen)) |
+  if  illegal_variable_width(vd, vm, SEW_widen, LMUL_pow_widen) |
       not(valid_reg_overlap(vs2, vd, LMUL_pow_widen, LMUL_pow))
   then { handle_illegal(); return RETIRE_FAIL };
 
@@ -281,7 +281,7 @@ function clause execute(NVTYPE(funct6, vm, vs2, vs1, vd)) = {
   let SEW_widen      = SEW * 2;
   let LMUL_pow_widen = LMUL_pow + 1;
 
-  if  not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_eew_emul(SEW_widen, LMUL_pow_widen)) |
+  if  illegal_variable_width(vd, vm, SEW_widen, LMUL_pow_widen) |
       not(valid_reg_overlap(vs2, vd, LMUL_pow_widen, LMUL_pow))
   then { handle_illegal(); return RETIRE_FAIL };
 
@@ -344,7 +344,7 @@ function clause execute(MASKTYPEV(vs2, vs1, vd)) = {
   let num_elem      = get_num_elem(LMUL_pow, SEW); /* max(VLMAX,VLEN/SEW)) */
   let real_num_elem = if LMUL_pow >= 0 then num_elem else num_elem / (0 - LMUL_pow); /* VLMAX */
 
-  if not(valid_vtype()) | vd == 0b00000 then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_masked(vd) then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -390,7 +390,7 @@ function clause execute(MOVETYPEV(vs1, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_unmasked() then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -449,7 +449,7 @@ function clause execute(VXTYPE(funct6, vm, vs2, rs1, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) | not(valid_rd_mask(vd, vm)) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_normal(vd, vm) then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -567,7 +567,7 @@ function clause execute(NXSTYPE(funct6, vm, vs2, rs1, vd)) = {
   let SEW_widen      = SEW * 2;
   let LMUL_pow_widen = LMUL_pow + 1;
 
-  if  not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_eew_emul(SEW_widen, LMUL_pow_widen)) |
+  if  illegal_variable_width(vd, vm, SEW_widen, LMUL_pow_widen) |
       not(valid_reg_overlap(vs2, vd, LMUL_pow_widen, LMUL_pow)) 
   then { handle_illegal(); return RETIRE_FAIL };
 
@@ -634,7 +634,7 @@ function clause execute(NXTYPE(funct6, vm, vs2, rs1, vd)) = {
   let SEW_widen      = SEW * 2;
   let LMUL_pow_widen = LMUL_pow + 1;
 
-  if  not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_eew_emul(SEW_widen, LMUL_pow_widen)) |
+  if  illegal_variable_width(vd, vm, SEW_widen, LMUL_pow_widen) |
       not(valid_reg_overlap(vs2, vd, LMUL_pow_widen, LMUL_pow)) 
   then { handle_illegal(); return RETIRE_FAIL };
 
@@ -703,7 +703,7 @@ function clause execute(VXSG(funct6, vm, vs2, rs1, vd)) = {
   let VLEN_pow = get_vlen_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) | not(valid_rd_mask(vd, vm)) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_normal(vd, vm) then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -767,7 +767,7 @@ function clause execute(MASKTYPEX(vs2, rs1, vd)) = {
   let num_elem      = get_num_elem(LMUL_pow, SEW); /* max(VLMAX,VLEN/SEW)) */
   let real_num_elem = if LMUL_pow >= 0 then num_elem else num_elem / (0 - LMUL_pow); /* VLMAX */
 
-  if not(valid_vtype()) | vd == 0b00000 then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_masked(vd) then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -813,7 +813,7 @@ function clause execute(MOVETYPEX(rs1, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_unmasked() then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -864,7 +864,7 @@ function clause execute(VITYPE(funct6, vm, vs2, simm, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) | not(valid_rd_mask(vd, vm)) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_normal(vd, vm) then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -958,7 +958,7 @@ function clause execute(NISTYPE(funct6, vm, vs2, simm, vd)) = {
   let SEW_widen      = SEW * 2;
   let LMUL_pow_widen = LMUL_pow + 1;
 
-  if  not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_eew_emul(SEW_widen, LMUL_pow_widen)) |
+  if  illegal_variable_width(vd, vm, SEW_widen, LMUL_pow_widen) |
       not(valid_reg_overlap(vs2, vd, LMUL_pow_widen, LMUL_pow))
   then { handle_illegal(); return RETIRE_FAIL };
 
@@ -1025,7 +1025,7 @@ function clause execute(NITYPE(funct6, vm, vs2, simm, vd)) = {
   let SEW_widen      = SEW * 2;
   let LMUL_pow_widen = LMUL_pow + 1;
 
-  if  not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_eew_emul(SEW_widen, LMUL_pow_widen)) |
+  if  illegal_variable_width(vd, vm, SEW_widen, LMUL_pow_widen) |
       not(valid_reg_overlap(vs2, vd, LMUL_pow_widen, LMUL_pow))
   then { handle_illegal(); return RETIRE_FAIL };
 
@@ -1094,7 +1094,7 @@ function clause execute(VISG(funct6, vm, vs2, simm, vd)) = {
   let VLEN_pow = get_vlen_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) | not(valid_rd_mask(vd, vm)) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_normal(vd, vm) then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -1158,7 +1158,7 @@ function clause execute(MASKTYPEI(vs2, simm, vd)) = {
   let num_elem      = get_num_elem(LMUL_pow, SEW); /* max(VLMAX,VLEN/SEW)) */
   let real_num_elem = if LMUL_pow >= 0 then num_elem else num_elem / (0 - LMUL_pow); /* VLMAX */
 
-  if not(valid_vtype()) | vd == 0b00000 then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_masked(vd) then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -1204,7 +1204,7 @@ function clause execute(MOVETYPEI(vd, simm)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_unmasked() then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -1298,7 +1298,7 @@ function clause execute(MVVTYPE(funct6, vm, vs2, vs1, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) | not(valid_rd_mask(vd, vm)) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_normal(vd, vm) then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -1408,7 +1408,7 @@ function clause execute(MVVMATYPE(funct6, vm, vs2, vs1, vd)) = {
   let VLEN     = int_power(2, get_vlen_pow());
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) | not(valid_rd_mask(vd, vm)) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_normal(vd, vm) then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -1471,7 +1471,7 @@ function clause execute(WVVTYPE(funct6, vm, vs2, vs1, vd)) = {
   let SEW_widen      = SEW * 2;
   let LMUL_pow_widen = LMUL_pow + 1;
 
-  if  not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_eew_emul(SEW_widen, LMUL_pow_widen)) |
+  if  illegal_variable_width(vd, vm, SEW_widen, LMUL_pow_widen) |
       not(valid_reg_overlap(vs1, vd, LMUL_pow, LMUL_pow_widen)) |
       not(valid_reg_overlap(vs2, vd, LMUL_pow, LMUL_pow_widen)) 
   then { handle_illegal(); return RETIRE_FAIL };
@@ -1542,7 +1542,7 @@ function clause execute(WVTYPE(funct6, vm, vs2, vs1, vd)) = {
   let SEW_widen      = SEW * 2;
   let LMUL_pow_widen = LMUL_pow + 1;
 
-  if  not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_eew_emul(SEW_widen, LMUL_pow_widen)) |
+  if  illegal_variable_width(vd, vm, SEW_widen, LMUL_pow_widen) |
       not(valid_reg_overlap(vs1, vd, LMUL_pow, LMUL_pow_widen)) 
   then { handle_illegal(); return RETIRE_FAIL };
 
@@ -1606,7 +1606,7 @@ function clause execute(WMVVTYPE(funct6, vm, vs2, vs1, vd)) = {
   let SEW_widen      = SEW * 2;
   let LMUL_pow_widen = LMUL_pow + 1;
 
-  if  not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_eew_emul(SEW_widen, LMUL_pow_widen)) |
+  if  illegal_variable_width(vd, vm, SEW_widen, LMUL_pow_widen) |
       not(valid_reg_overlap(vs1, vd, LMUL_pow, LMUL_pow_widen)) | 
       not(valid_reg_overlap(vs2, vd, LMUL_pow, LMUL_pow_widen)) 
   then { handle_illegal(); return RETIRE_FAIL };
@@ -1668,7 +1668,7 @@ function clause execute(VEXT2TYPE(funct6, vm, vs2, vd)) = {
   let SEW_half = SEW / 2;
   let LMUL_pow_half = LMUL_pow - 1;
 
-  if  not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_eew_emul(SEW_half, LMUL_pow_half)) |
+  if  illegal_variable_width(vd, vm, SEW_half, LMUL_pow_half) |
       not(valid_reg_overlap(vs2, vd, LMUL_pow_half, LMUL_pow)) 
   then { handle_illegal(); return RETIRE_FAIL };
 
@@ -1726,7 +1726,7 @@ function clause execute(VEXT4TYPE(funct6, vm, vs2, vd)) = {
   let SEW_quart = SEW / 4;
   let LMUL_pow_quart = LMUL_pow - 2;
 
-  if  not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_eew_emul(SEW_quart, LMUL_pow_quart)) |
+  if  illegal_variable_width(vd, vm, SEW_quart, LMUL_pow_quart) |
       not(valid_reg_overlap(vs2, vd, LMUL_pow_quart, LMUL_pow))
   then { handle_illegal(); return RETIRE_FAIL };
 
@@ -1784,7 +1784,7 @@ function clause execute(VEXT8TYPE(funct6, vm, vs2, vd)) = {
   let SEW_eighth = SEW / 8;
   let LMUL_pow_eighth = LMUL_pow - 3;
 
-  if  not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_eew_emul(SEW_eighth, LMUL_pow_eighth)) |
+  if  illegal_variable_width(vd, vm, SEW_eighth, LMUL_pow_eighth) |
       not(valid_reg_overlap(vs2, vd, LMUL_pow_eighth, LMUL_pow))
   then { handle_illegal(); return RETIRE_FAIL };
 
@@ -1833,7 +1833,7 @@ function clause execute(VMVXS(vs2, rd)) = {
   let SEW      = get_sew();
   let num_elem = get_num_elem(0, SEW);
 
-  if not(valid_vtype()) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_unmasked() then { handle_illegal(); return RETIRE_FAIL };
 
   assert(num_elem > 0);
   let 'n = num_elem;
@@ -1865,7 +1865,7 @@ function clause execute(MVVCOMPRESS(vs2, vs1, vd)) = {
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
   /* vcompress should always be executed with a vstart of 0 */
-  if start_element != 0 | vs1 == vd | vs2 == vd | not(valid_vtype())
+  if start_element != 0 | vs1 == vd | vs2 == vd | illegal_vd_unmasked()
   then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
@@ -1935,7 +1935,7 @@ function clause execute(MVXTYPE(funct6, vm, vs2, rs1, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) | not(valid_rd_mask(vd, vm)) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_normal(vd, vm) then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -2056,7 +2056,7 @@ function clause execute(MVXMATYPE(funct6, vm, vs2, rs1, vd)) = {
   let VLEN     = int_power(2, get_vlen_pow());
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) | not(valid_rd_mask(vd, vm)) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_normal(vd, vm) then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -2120,7 +2120,7 @@ function clause execute(WVXTYPE(funct6, vm, vs2, rs1, vd)) = {
   let SEW_widen      = SEW * 2;
   let LMUL_pow_widen = LMUL_pow + 1;
 
-  if  not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_eew_emul(SEW_widen, LMUL_pow_widen)) |
+  if  illegal_variable_width(vd, vm, SEW_widen, LMUL_pow_widen) |
       not(valid_reg_overlap(vs2, vd, LMUL_pow, LMUL_pow_widen))
   then { handle_illegal(); return RETIRE_FAIL };
 
@@ -2190,7 +2190,7 @@ function clause execute(WXTYPE(funct6, vm, vs2, rs1, vd)) = {
   let SEW_widen      = SEW * 2;
   let LMUL_pow_widen = LMUL_pow + 1;
 
-  if not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_eew_emul(SEW_widen, LMUL_pow_widen)) 
+  if illegal_variable_width(vd, vm, SEW_widen, LMUL_pow_widen) 
   then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
@@ -2254,7 +2254,7 @@ function clause execute(WMVXTYPE(funct6, vm, vs2, rs1, vd)) = {
   let SEW_widen      = SEW * 2;
   let LMUL_pow_widen = LMUL_pow + 1;
 
-  if  not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_eew_emul(SEW_widen, LMUL_pow_widen)) |
+  if  illegal_variable_width(vd, vm, SEW_widen, LMUL_pow_widen) |
       not(valid_reg_overlap(vs2, vd, LMUL_pow, LMUL_pow_widen))
   then { handle_illegal(); return RETIRE_FAIL };
 
@@ -2308,7 +2308,7 @@ function clause execute(VMVSX(rs1, vd)) = {
   let SEW      = get_sew();
   let num_elem = get_num_elem(0, SEW);
 
-  if not(valid_vtype()) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_unmasked() then { handle_illegal(); return RETIRE_FAIL };
 
   assert(num_elem > 0);
   let 'n = num_elem;
diff --git a/model/riscv_insts_vext_fp.sail b/model/riscv_insts_vext_fp.sail
index 293c606c9..2e0e2570d 100755
--- a/model/riscv_insts_vext_fp.sail
+++ b/model/riscv_insts_vext_fp.sail
@@ -66,8 +66,7 @@ function clause execute(FVVTYPE(funct6, vm, vs2, vs1, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_fp_op(SEW, rm_3b)) 
-  then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_fp_normal(vd, vm, SEW, rm_3b) then { handle_illegal(); return RETIRE_FAIL };
   assert(SEW != 8);
 
   let 'n = num_elem;
@@ -142,8 +141,7 @@ function clause execute(FVVMATYPE(funct6, vm, vs2, vs1, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_fp_op(SEW, rm_3b)) 
-  then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_fp_normal(vd, vm, SEW, rm_3b) then { handle_illegal(); return RETIRE_FAIL };
   assert(SEW != 8);
 
   let 'n = num_elem;
@@ -212,8 +210,7 @@ function clause execute(FWVVTYPE(funct6, vm, vs2, vs1, vd)) = {
   let SEW_widen      = SEW * 2;
   let LMUL_pow_widen = LMUL_pow + 1;
 
-  if  not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_fp_op(SEW, rm_3b)) | 
-      not(valid_eew_emul(SEW_widen, LMUL_pow_widen)) |
+  if  illegal_fp_variable_width(vd, vm, SEW, rm_3b, SEW_widen, LMUL_pow_widen) |
       not(valid_reg_overlap(vs1, vd, LMUL_pow, LMUL_pow_widen)) | 
       not(valid_reg_overlap(vs2, vd, LMUL_pow, LMUL_pow_widen)) 
   then { handle_illegal(); return RETIRE_FAIL };
@@ -278,8 +275,7 @@ function clause execute(FWVVMATYPE(funct6, vm, vs1, vs2, vd)) = {
   let SEW_widen      = SEW * 2;
   let LMUL_pow_widen = LMUL_pow + 1;
 
-  if  not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_fp_op(SEW, rm_3b)) | 
-      not(valid_eew_emul(SEW_widen, LMUL_pow_widen)) |
+  if  illegal_fp_variable_width(vd, vm, SEW, rm_3b, SEW_widen, LMUL_pow_widen) |
       not(valid_reg_overlap(vs1, vd, LMUL_pow, LMUL_pow_widen)) | 
       not(valid_reg_overlap(vs2, vd, LMUL_pow, LMUL_pow_widen))
   then { handle_illegal(); return RETIRE_FAIL };
@@ -343,8 +339,7 @@ function clause execute(FWVTYPE(funct6, vm, vs2, vs1, vd)) = {
   let SEW_widen      = SEW * 2;
   let LMUL_pow_widen = LMUL_pow + 1;
 
-  if  not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_fp_op(SEW, rm_3b)) | 
-      not(valid_eew_emul(SEW_widen, LMUL_pow_widen)) |
+  if  illegal_fp_variable_width(vd, vm, SEW, rm_3b, SEW_widen, LMUL_pow_widen) |
       not(valid_reg_overlap(vs1, vd, LMUL_pow, LMUL_pow_widen))
   then { handle_illegal(); return RETIRE_FAIL };
   assert(SEW >= 16 & SEW_widen <= 64);
@@ -405,8 +400,7 @@ function clause execute(VFUNARY0(vm, vs2, vfunary0, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_fp_op(SEW, rm_3b)) 
-  then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_fp_normal(vd, vm, SEW, rm_3b) then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -521,8 +515,7 @@ function clause execute(VFWUNARY0(vm, vs2, vfwunary0, vd)) = {
   let SEW_widen      = SEW * 2;
   let LMUL_pow_widen = LMUL_pow + 1;
 
-  if  not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_fp_op(SEW, rm_3b)) |
-      not(valid_eew_emul(SEW_widen, LMUL_pow_widen)) |
+  if  illegal_fp_variable_width(vd, vm, SEW, rm_3b, SEW_widen, LMUL_pow_widen) |
       not(valid_reg_overlap(vs2, vd, LMUL_pow, LMUL_pow_widen))
   then { handle_illegal(); return RETIRE_FAIL };
   assert(SEW >= 8 & SEW_widen <= 64);
@@ -652,8 +645,7 @@ function clause execute(VFNUNARY0(vm, vs2, vfnunary0, vd)) = {
   let SEW_widen      = SEW * 2;
   let LMUL_pow_widen = LMUL_pow + 1;
 
-  if  not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_fp_op(SEW, rm_3b)) |
-      not(valid_eew_emul(SEW_widen, LMUL_pow_widen)) |
+  if  illegal_fp_variable_width(vd, vm, SEW, rm_3b, SEW_widen, LMUL_pow_widen) |
       not(valid_reg_overlap(vs2, vd, LMUL_pow_widen, LMUL_pow))
   then { handle_illegal(); return RETIRE_FAIL };
 
@@ -786,8 +778,7 @@ function clause execute(VFUNARY1(vm, vs2, vfunary1, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_fp_op(SEW, rm_3b))
-  then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_fp_normal(vd, vm, SEW, rm_3b) then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -869,7 +860,7 @@ function clause execute(VFMVFS(vs2, rd)) = {
   let SEW      = get_sew();
   let num_elem = get_num_elem(0, SEW);
 
-  if not(valid_vtype()) | not(valid_fp_op(SEW, rm_3b)) | SEW > sizeof(flen)
+  if illegal_fp_vd_unmasked(SEW, rm_3b) | SEW > sizeof(flen)
   then { handle_illegal(); return RETIRE_FAIL };
   assert(num_elem > 0 & SEW != 8);
 
@@ -915,8 +906,7 @@ function clause execute(FVFTYPE(funct6, vm, vs2, rs1, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_fp_op(SEW, rm_3b))
-  then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_fp_normal(vd, vm, SEW, rm_3b) then { handle_illegal(); return RETIRE_FAIL };
   assert(SEW != 8);
 
   let 'n = num_elem;
@@ -1006,8 +996,7 @@ function clause execute(FVFMATYPE(funct6, vm, vs2, rs1, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_fp_op(SEW, rm_3b))
-  then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_fp_normal(vd, vm, SEW, rm_3b) then { handle_illegal(); return RETIRE_FAIL };
   assert(SEW != 8);
 
   let 'n = num_elem;
@@ -1076,8 +1065,7 @@ function clause execute(FWVFTYPE(funct6, vm, vs2, rs1, vd)) = {
   let SEW_widen      = SEW * 2;
   let LMUL_pow_widen = LMUL_pow + 1;
 
-  if  not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_fp_op(SEW, rm_3b)) |
-      not(valid_eew_emul(SEW_widen, LMUL_pow_widen)) |
+  if  illegal_fp_variable_width(vd, vm, SEW, rm_3b, SEW_widen, LMUL_pow_widen) |
       not(valid_reg_overlap(vs2, vd, LMUL_pow, LMUL_pow_widen)) 
   then { handle_illegal(); return RETIRE_FAIL };
   assert(SEW >= 16 & SEW_widen <= 64);
@@ -1141,8 +1129,7 @@ function clause execute(FWVFMATYPE(funct6, vm, rs1, vs2, vd)) = {
   let SEW_widen      = SEW * 2;
   let LMUL_pow_widen = LMUL_pow + 1;
 
-  if  not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_fp_op(SEW, rm_3b)) |
-      not(valid_eew_emul(SEW_widen, LMUL_pow_widen)) |
+  if  illegal_fp_variable_width(vd, vm, SEW, rm_3b, SEW_widen, LMUL_pow_widen) |
       not(valid_reg_overlap(vs2, vd, LMUL_pow, LMUL_pow_widen))
   then { handle_illegal(); return RETIRE_FAIL };
   assert(SEW >= 16 & SEW_widen <= 64);
@@ -1205,8 +1192,7 @@ function clause execute(FWFTYPE(funct6, vm, vs2, rs1, vd)) = {
   let SEW_widen      = SEW * 2;
   let LMUL_pow_widen = LMUL_pow + 1;
 
-  if  not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_fp_op(SEW, rm_3b)) |
-      not(valid_eew_emul(SEW_widen, LMUL_pow_widen))
+  if illegal_fp_variable_width(vd, vm, SEW, rm_3b, SEW_widen, LMUL_pow_widen)
   then { handle_illegal(); return RETIRE_FAIL };
   assert(SEW >= 16 & SEW_widen <= 64);
 
@@ -1261,8 +1247,7 @@ function clause execute(VFMERGE(vs2, rs1, vd)) = {
   let num_elem      = get_num_elem(LMUL_pow, SEW); /* max(VLMAX,VLEN/SEW)) */
   let real_num_elem = if LMUL_pow >= 0 then num_elem else num_elem / (0 - LMUL_pow); /* VLMAX */
 
-  if not(valid_vtype()) | vd == 0b00000 | not(valid_fp_op(SEW, rm_3b))
-  then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_fp_vd_masked(vd, SEW, rm_3b) then { handle_illegal(); return RETIRE_FAIL };
   assert(SEW != 8);
 
   let 'n = num_elem;
@@ -1311,7 +1296,7 @@ function clause execute(VFMV(rs1, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) | not(valid_fp_op(SEW, rm_3b)) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_fp_vd_unmasked(SEW, rm_3b) then { handle_illegal(); return RETIRE_FAIL };
   assert(SEW != 8);
 
   let 'n = num_elem;
@@ -1348,7 +1333,7 @@ function clause execute(VFMVSF(rs1, vd)) = {
   let SEW      = get_sew();
   let num_elem = get_num_elem(0, SEW);
 
-  if not(valid_vtype()) | not(valid_fp_op(SEW, rm_3b)) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_fp_vd_unmasked(SEW, rm_3b) then { handle_illegal(); return RETIRE_FAIL };
   assert(num_elem > 0 & SEW != 8);
 
   let 'n = num_elem;
diff --git a/model/riscv_insts_vext_mask.sail b/model/riscv_insts_vext_mask.sail
index bdfe20ae4..5f1be7af6 100755
--- a/model/riscv_insts_vext_mask.sail
+++ b/model/riscv_insts_vext_mask.sail
@@ -63,7 +63,7 @@ function clause execute(MMTYPE(funct6, vs2, vs1, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = int_power(2, get_vlen_pow());
 
-  if not(valid_vtype()) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_unmasked() then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -122,7 +122,7 @@ function clause execute(VCPOP_M(vm, vs2, rd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = int_power(2, get_vlen_pow());
 
-  if not(valid_vtype()) | not(assert_vstart(0)) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_unmasked() | not(assert_vstart(0)) then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -158,7 +158,7 @@ function clause execute(VFIRST_M(vm, vs2, rd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = int_power(2, get_vlen_pow());
 
-  if not(valid_vtype()) | not(assert_vstart(0)) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_unmasked() | not(assert_vstart(0)) then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -196,7 +196,7 @@ function clause execute(VMSBF_M(vm, vs2, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = int_power(2, get_vlen_pow());
 
-  if not(valid_vtype()) | not(assert_vstart(0)) | not(valid_rd_mask(vd, vm)) | vd == vs2
+  if illegal_normal(vd, vm) | not(assert_vstart(0)) | vd == vs2
   then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
@@ -237,7 +237,7 @@ function clause execute(VMSIF_M(vm, vs2, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = int_power(2, get_vlen_pow());
 
-  if not(valid_vtype()) | not(assert_vstart(0)) | not(valid_rd_mask(vd, vm)) | vd == vs2
+  if illegal_normal(vd, vm) | not(assert_vstart(0)) | vd == vs2
   then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
@@ -278,7 +278,7 @@ function clause execute(VMSOF_M(vm, vs2, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = int_power(2, get_vlen_pow());
 
-  if not(valid_vtype()) | not(assert_vstart(0)) | not(valid_rd_mask(vd, vm)) | vd == vs2
+  if illegal_normal(vd, vm) | not(assert_vstart(0)) | vd == vs2
   then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
@@ -323,7 +323,7 @@ function clause execute(VIOTA_M(vm, vs2, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) | not(assert_vstart(0)) | not(valid_rd_mask(vd, vm)) | vd == vs2
+  if illegal_normal(vd, vm) | not(assert_vstart(0)) | vd == vs2
   then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
@@ -364,7 +364,7 @@ function clause execute(VID_V(vm, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) | not(valid_rd_mask(vd, vm)) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_normal(vd, vm) then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
diff --git a/model/riscv_insts_vext_mem.sail b/model/riscv_insts_vext_mem.sail
index a001cfb56..796ea4ad8 100644
--- a/model/riscv_insts_vext_mem.sail
+++ b/model/riscv_insts_vext_mem.sail
@@ -153,7 +153,7 @@ function clause execute(VLETYPE(vm, rs1, width, vd)) = {
   let EMUL_pow = EEW_pow - SEW_pow + LMUL_pow;
   let num_elem = get_num_elem(EMUL_pow, EEW);
 
-  if not(valid_vtype()) | not(valid_rd_mask(vd, vm)) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_normal(vd, vm) then { handle_illegal(); return RETIRE_FAIL };
 
   process_vle(vm, vd, load_width_bytes, rs1, EMUL_pow, num_elem)
 }
@@ -230,7 +230,7 @@ function clause execute(VSETYPE(vm, rs1, width, vs3)) = {
   let EMUL_pow = EEW_pow - SEW_pow + LMUL_pow;
   let num_elem = get_num_elem(EMUL_pow, EEW);
 
-  if not(valid_vtype()) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_unmasked() then { handle_illegal(); return RETIRE_FAIL };
 
   process_vse(vm, vs3, load_width_bytes, rs1, EMUL_pow, num_elem)
 }
@@ -301,7 +301,7 @@ function clause execute(VLSETYPE(vm, rs2, rs1, width, vd)) = {
   let EMUL_pow = EEW_pow - SEW_pow + LMUL_pow;
   let num_elem = get_num_elem(EMUL_pow, EEW);
 
-  if not(valid_vtype()) | not(valid_rd_mask(vd, vm)) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_normal(vd, vm) then { handle_illegal(); return RETIRE_FAIL };
 
   process_vlse(vm, vd, load_width_bytes, rs1, rs2, EMUL_pow, num_elem)
 }
@@ -379,7 +379,7 @@ function clause execute(VSSETYPE(vm, rs2, rs1, width, vs3)) = {
   let EMUL_pow = EEW_pow - SEW_pow + LMUL_pow;
   let num_elem = get_num_elem(EMUL_pow, EEW);
 
-  if not(valid_vtype()) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_unmasked() then { handle_illegal(); return RETIRE_FAIL };
 
   process_vsse(vm, vs3, load_width_bytes, rs1, rs2, EMUL_pow, num_elem)
 }
@@ -450,7 +450,7 @@ function clause execute(VLUXEITYPE(vm, vs2, rs1, width, vd)) = {
   let EMUL_index_pow = EEW_index_pow - EEW_data_pow + EMUL_data_pow;
   let num_elem = get_num_elem(EMUL_data_pow, EEW_data_bytes * 8);
 
-  if not(valid_vtype()) | not(valid_rd_mask(vd, vm)) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_normal(vd, vm) then { handle_illegal(); return RETIRE_FAIL };
 
   process_vlxei(vm, vd, EEW_index_bytes, EEW_data_bytes, EMUL_index_pow, EMUL_data_pow, rs1, vs2, num_elem, 1)
 }
@@ -473,7 +473,7 @@ function clause execute(VLOXEITYPE(vm, vs2, rs1, width, vd)) = {
   let EMUL_index_pow = EEW_index_pow - EEW_data_pow + EMUL_data_pow;
   let num_elem = get_num_elem(EMUL_data_pow, EEW_data_bytes * 8);
 
-  if not(valid_vtype()) | not(valid_rd_mask(vd, vm)) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_normal(vd, vm) then { handle_illegal(); return RETIRE_FAIL };
 
   process_vlxei(vm, vd, EEW_index_bytes, EEW_data_bytes, EMUL_index_pow, EMUL_data_pow, rs1, vs2, num_elem, 3)
 }
@@ -544,7 +544,7 @@ function clause execute(VSUXEITYPE(vm, vs2, rs1, width, vs3)) = {
   let EMUL_index_pow = EEW_index_pow - EEW_data_pow + EMUL_data_pow;
   let num_elem = get_num_elem(EMUL_data_pow, EEW_data_bytes * 8); /* number of data and indices are the same */
 
-  if not(valid_vtype()) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_unmasked() then { handle_illegal(); return RETIRE_FAIL };
 
   process_vsxei(vm, vs3, EEW_index_bytes, EEW_data_bytes, EMUL_index_pow, EMUL_data_pow, rs1, vs2, num_elem, 1)
 }
@@ -567,7 +567,7 @@ function clause execute(VSOXEITYPE(vm, vs2, rs1, width, vs3)) = {
   let EMUL_index_pow = EEW_index_pow - EEW_data_pow + EMUL_data_pow;
   let num_elem = get_num_elem(EMUL_data_pow, EEW_data_bytes * 8); /* number of data and indices are the same */
 
-  if not(valid_vtype()) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_unmasked() then { handle_illegal(); return RETIRE_FAIL };
 
   process_vsxei(vm, vs3, EEW_index_bytes, EEW_data_bytes, EMUL_index_pow, EMUL_data_pow, rs1, vs2, num_elem, 3)
 }
@@ -659,7 +659,7 @@ function clause execute(VLEFFTYPE(vm, rs1, width, vd)) = {
   let EMUL_pow = EEW_pow - SEW_pow + LMUL_pow;
   let num_elem = get_num_elem(EMUL_pow, EEW);
 
-  if not(valid_vtype()) | not(valid_rd_mask(vd, vm)) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_normal(vd, vm) then { handle_illegal(); return RETIRE_FAIL };
 
   process_vleff(vm, vd, load_width_bytes, rs1, EMUL_pow, num_elem)
 }
@@ -739,7 +739,7 @@ function clause execute(VLSEGTYPE(nf, vm, rs1, width, vd)) = {
   let num_elem = get_num_elem(EMUL_pow, EEW); /* # of element of each register group */
   let nf_int = nfields_int(nf);
 
-  if not(valid_vtype()) | not(valid_rd_mask(vd, vm)) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_normal(vd, vm) then { handle_illegal(); return RETIRE_FAIL };
 
   process_vlseg(nf_int, vm, vd, load_width_bytes, rs1, EMUL_pow, num_elem)
 }
@@ -832,7 +832,7 @@ function clause execute(VLSEGFFTYPE(nf, vm, rs1, width, vd)) = {
   let num_elem = get_num_elem(EMUL_pow, EEW);
   let nf_int = nfields_int(nf);
 
-  if not(valid_vtype()) | not(valid_rd_mask(vd, vm)) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_normal(vd, vm) then { handle_illegal(); return RETIRE_FAIL };
 
   process_vlsegff(nf_int, vm, vd, load_width_bytes, rs1, EMUL_pow, num_elem)
 }
@@ -904,7 +904,7 @@ function clause execute(VSSEGTYPE(nf, vm, rs1, width, vs3)) = {
   let num_elem = get_num_elem(EMUL_pow, EEW);
   let nf_int = nfields_int(nf);
 
-  if not(valid_vtype()) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_unmasked() then { handle_illegal(); return RETIRE_FAIL };
 
   process_vsseg(nf_int, vm, vs3, load_width_bytes, rs1, EMUL_pow, num_elem)
 }
@@ -970,7 +970,7 @@ function clause execute(VLSSEGTYPE(nf, vm, rs2, rs1, width, vd)) = {
   let num_elem = get_num_elem(EMUL_pow, EEW);
   let nf_int = nfields_int(nf);
 
-  if not(valid_vtype()) | not(valid_rd_mask(vd, vm)) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_normal(vd, vm) then { handle_illegal(); return RETIRE_FAIL };
 
   process_vlsseg(nf_int, vm, vd, load_width_bytes, rs1, rs2, EMUL_pow, num_elem)
 }
@@ -1045,7 +1045,7 @@ function clause execute(VSSSEGTYPE(nf, vm, rs2, rs1, width, vs3)) = {
   let num_elem = get_num_elem(EMUL_pow, EEW);
   let nf_int = nfields_int(nf);
 
-  if not(valid_vtype()) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_unmasked() then { handle_illegal(); return RETIRE_FAIL };
 
   process_vssseg(nf_int, vm, vs3, load_width_bytes, rs1, rs2, EMUL_pow, num_elem)
 }
@@ -1112,7 +1112,7 @@ function clause execute(VLUXSEGTYPE(nf, vm, vs2, rs1, width, vd)) = {
   let num_elem = get_num_elem(EMUL_data_pow, EEW_data_bytes * 8);
   let nf_int = nfields_int(nf);
 
-  if not(valid_vtype()) | not(valid_rd_mask(vd, vm)) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_normal(vd, vm) then { handle_illegal(); return RETIRE_FAIL };
 
   process_vlxseg(nf_int, vm, vd, EEW_index_bytes, EEW_data_bytes, EMUL_index_pow, EMUL_data_pow, rs1, vs2, num_elem, 1)
 }
@@ -1136,7 +1136,7 @@ function clause execute(VLOXSEGTYPE(nf, vm, vs2, rs1, width, vd)) = {
   let num_elem = get_num_elem(EMUL_data_pow, EEW_data_bytes * 8);
   let nf_int = nfields_int(nf);
 
-  if not(valid_vtype()) | not(valid_rd_mask(vd, vm)) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_normal(vd, vm) then { handle_illegal(); return RETIRE_FAIL };
 
   process_vlxseg(nf_int, vm, vd, EEW_index_bytes, EEW_data_bytes, EMUL_index_pow, EMUL_data_pow, rs1, vs2, num_elem, 3)
 }
@@ -1212,7 +1212,7 @@ function clause execute(VSUXSEGTYPE(nf, vm, vs2, rs1, width, vs3)) = {
   let num_elem = get_num_elem(EMUL_data_pow, EEW_data_bytes * 8); /* number of data and indices are the same */
   let nf_int = nfields_int(nf);
 
-  if not(valid_vtype()) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_unmasked() then { handle_illegal(); return RETIRE_FAIL };
 
   process_vsxseg(nf_int, vm, vs3, EEW_index_bytes, EEW_data_bytes, EMUL_index_pow, EMUL_data_pow, rs1, vs2, num_elem, 1)
 }
@@ -1236,7 +1236,7 @@ function clause execute(VSOXSEGTYPE(nf, vm, vs2, rs1, width, vs3)) = {
   let num_elem = get_num_elem(EMUL_data_pow, EEW_data_bytes * 8); /* number of data and indices are the same */
   let nf_int = nfields_int(nf);
 
-  if not(valid_vtype()) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_unmasked() then { handle_illegal(); return RETIRE_FAIL };
 
   process_vsxseg(nf_int, vm, vs3, EEW_index_bytes, EEW_data_bytes, EMUL_index_pow, EMUL_data_pow, rs1, vs2, num_elem, 3)
 }
@@ -1520,7 +1520,7 @@ function clause execute(VMTYPE(rs1, vd_or_vs3, op)) = {
   let tmp = unsigned(vl);
   let num_elem : int = if tmp % 8 == 0 then tmp / 8 else tmp / 8 + 1;
 
-  if not(valid_vtype()) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_unmasked() then { handle_illegal(); return RETIRE_FAIL };
 
   /* unmask vle8 except that the effective vector length is evl=ceil(vl/8) */
   assert(num_elem >= 0);
diff --git a/model/riscv_insts_vext_red.sail b/model/riscv_insts_vext_red.sail
index 714cf805b..afa0b95ea 100755
--- a/model/riscv_insts_vext_red.sail
+++ b/model/riscv_insts_vext_red.sail
@@ -59,8 +59,7 @@ function clause execute(RIVVTYPE(funct6, vm, vs2, vs1, vd)) = {
   let SEW_widen      = SEW * 2;
   let LMUL_pow_widen = LMUL_pow + 1;
 
-  if not(valid_vtype()) | not(assert_vstart(0)) | not(valid_eew_emul(SEW_widen, LMUL_pow_widen))
-  then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_reduction_widen(SEW_widen, LMUL_pow_widen) then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -125,7 +124,7 @@ function clause execute(RMVVTYPE(funct6, vm, vs2, vs1, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) | not(assert_vstart(0)) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_reduction() then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -191,8 +190,7 @@ mapping clause encdec = RFVVTYPE(funct6, vm, vs2, vs1, vd) if haveRVV()
 val process_rfvv_single: forall 'n 'm 'p, 'm in {8, 16, 32, 64}. (rfvvfunct6, bits(1), regidx, regidx, regidx, int('n), int('m), int('p)) -> Retired effect {escape, rreg, undef, wreg}
 function process_rfvv_single(funct6, vm, vs2, vs1, vd, num_elem, SEW, LMUL_pow) = {
   let rm_3b = fcsr.FRM();
-  if not(valid_vtype()) | not(assert_vstart(0)) | not(valid_fp_op(SEW, rm_3b))
-  then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_fp_reduction(SEW, rm_3b) then { handle_illegal(); return RETIRE_FAIL };
   assert(SEW != 8);
 
   let 'n = num_elem;
@@ -229,9 +227,7 @@ function process_rfvv_widen(funct6, vm, vs2, vs1, vd, num_elem, SEW, LMUL_pow) =
   let SEW_widen      = SEW * 2;
   let LMUL_pow_widen = LMUL_pow + 1;
 
-  if  not(valid_vtype()) | not(assert_vstart(0)) | not(valid_fp_op(SEW, rm_3b)) |
-      not(valid_eew_emul(SEW_widen, LMUL_pow_widen))
-  then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_fp_reduction_widen(SEW, rm_3b, SEW_widen, LMUL_pow_widen) then { handle_illegal(); return RETIRE_FAIL };
   assert(SEW >= 16 & SEW_widen <= 64);
 
   let 'n = num_elem;
diff --git a/model/riscv_insts_vext_utils.sail b/model/riscv_insts_vext_utils.sail
index d6afec730..d498cbe01 100755
--- a/model/riscv_insts_vext_utils.sail
+++ b/model/riscv_insts_vext_utils.sail
@@ -112,6 +112,96 @@ function valid_reg_overlap(rs, rd, EMUL_pow_rs, EMUL_pow_rd) = {
   is_valid
 }
 
+/* ******************************************************************************* */
+/* The following functions summarize patterns of illegal instruction check.        */
+/* ******************************************************************************* */
+
+/* a. Normal check including vtype.vill field and vd/v0 overlap if vm = 0 */
+val illegal_normal : (regidx, bits(1)) -> bool
+function illegal_normal(vd, vm) = {
+  not(valid_vtype()) | not(valid_rd_mask(vd, vm))
+}
+
+/* b. Masked check for instructions encoded with vm = 0 */
+val illegal_vd_masked : regidx -> bool
+function illegal_vd_masked(vd) = {
+  not(valid_vtype()) | vd == 0b00000
+}
+
+/* c. Unmasked check for:
+ *  1. instructions encoded with vm = 1
+ *  2. instructions with scalar rd: vcpop.m, vfirst.m
+ *  3. instructions with vs3 rather than vd: vector stores
+ *  4. vd as mask register (eew = 1): 
+ *     vmadc.vvm/vxm/vim, vmsbc.vvm/vxm, mask logical, integer compare, vlm.v, vsm.v
+ */
+val illegal_vd_unmasked : unit -> bool
+function illegal_vd_unmasked() = {
+  not(valid_vtype())
+}
+
+/* d. Variable width check for:
+ *  1. integer/fixed-point widening/narrowing instructions
+ *  2. vector integer extension: vzext, vsext
+ */
+val illegal_variable_width : (regidx, bits(1), int, int) -> bool
+function illegal_variable_width(vd, vm, SEW_new, LMUL_pow_new) = {
+  not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_eew_emul(SEW_new, LMUL_pow_new))
+}
+
+/* e. Normal check for reduction instructions:
+ *  The destination vector register can overlap the source operands, including the mask register.
+ *  Vector reduction operations raise an illegal instruction exception if vstart is non-zero.
+ */
+val illegal_reduction : unit -> bool
+function illegal_reduction() = {
+  not(valid_vtype()) | not(assert_vstart(0))
+}
+
+/* f. Variable width check for widening reduction instructions */  
+val illegal_reduction_widen : (int, int) -> bool
+function illegal_reduction_widen(SEW_widen, LMUL_pow_widen) = {
+  not(valid_vtype()) | not(assert_vstart(0)) | not(valid_eew_emul(SEW_widen, LMUL_pow_widen))
+}
+
+/* g. Normal check for floating-point instructions */
+val illegal_fp_normal : (regidx, bits(1), {|8, 16, 32, 64|}, bits(3)) -> bool
+function illegal_fp_normal(vd, vm, SEW, rm_3b) = {
+  not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_fp_op(SEW, rm_3b))
+}
+
+/* h. Masked check for floating-point instructions encoded with vm = 0 */
+val illegal_fp_vd_masked : (regidx, {|8, 16, 32, 64|}, bits(3)) -> bool
+function illegal_fp_vd_masked(vd, SEW, rm_3b) = {
+  not(valid_vtype()) | vd == 0b00000 | not(valid_fp_op(SEW, rm_3b))
+}
+
+/* i. Unmasked check for floating-point instructions encoded with vm = 1 */
+val illegal_fp_vd_unmasked : ({|8, 16, 32, 64|}, bits(3)) -> bool
+function illegal_fp_vd_unmasked(SEW, rm_3b) = {
+  not(valid_vtype()) | not(valid_fp_op(SEW, rm_3b))
+}
+
+/* j. Variable width check for floating-point widening/narrowing instructions */
+val illegal_fp_variable_width : (regidx, bits(1), {|8, 16, 32, 64|}, bits(3), int, int) -> bool
+function illegal_fp_variable_width(vd, vm, SEW, rm_3b, SEW_new, LMUL_pow_new) = {
+  not(valid_vtype()) | not(valid_rd_mask(vd, vm)) | not(valid_fp_op(SEW, rm_3b)) | 
+  not(valid_eew_emul(SEW_new, LMUL_pow_new))
+}
+
+/* k. Normal check for floating-point reduction instructions */
+val illegal_fp_reduction : ({|8, 16, 32, 64|}, bits(3)) -> bool
+function illegal_fp_reduction(SEW, rm_3b) = {
+  not(valid_vtype()) | not(assert_vstart(0)) | not(valid_fp_op(SEW, rm_3b))
+}
+
+/* l. Variable width check for floating-point widening reduction instructions */
+val illegal_fp_reduction_widen : ({|8, 16, 32, 64|}, bits(3), int, int) -> bool
+function illegal_fp_reduction_widen(SEW, rm_3b, SEW_widen, LMUL_pow_widen) = {
+  not(valid_vtype()) | not(assert_vstart(0)) | not(valid_fp_op(SEW, rm_3b)) |
+  not(valid_eew_emul(SEW_widen, LMUL_pow_widen))
+}
+
 /* Scalar register shaping */
 val get_scalar : forall 'n, 'n >= 8. (regidx, int('n)) -> bits('n) effect {escape, rreg}
 function get_scalar(rs1, SEW) = {
diff --git a/model/riscv_insts_vext_vm.sail b/model/riscv_insts_vext_vm.sail
index 47af56626..6784ce7e4 100755
--- a/model/riscv_insts_vext_vm.sail
+++ b/model/riscv_insts_vext_vm.sail
@@ -60,7 +60,7 @@ function clause execute(VVMTYPE(funct6, vs2, vs1, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_unmasked() then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -116,7 +116,7 @@ function clause execute(VVMCTYPE(funct6, vs2, vs1, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_unmasked() then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -171,7 +171,7 @@ function clause execute(VVMSTYPE(funct6, vs2, vs1, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) | vd == 0b00000 then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_masked(vd) then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -234,7 +234,7 @@ function clause execute(VVCMPTYPE(funct6, vm, vs2, vs1, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_unmasked() then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -298,7 +298,7 @@ function clause execute(VXMTYPE(funct6, vs2, rs1, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_unmasked() then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -354,7 +354,7 @@ function clause execute(VXMCTYPE(funct6, vs2, rs1, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_unmasked() then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -409,7 +409,7 @@ function clause execute(VXMSTYPE(funct6, vs2, rs1, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) | vd == 0b00000 then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_masked(vd) then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -474,7 +474,7 @@ function clause execute(VXCMPTYPE(funct6, vm, vs2, rs1, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_unmasked() then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -541,7 +541,7 @@ function clause execute(VIMTYPE(funct6, vs2, simm, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_unmasked() then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -594,7 +594,7 @@ function clause execute(VIMCTYPE(funct6, vs2, simm, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_unmasked() then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -646,7 +646,7 @@ function clause execute(VIMSTYPE(funct6, vs2, simm, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) | vd == 0b00000 then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_masked(vd) then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -707,7 +707,7 @@ function clause execute(VICMPTYPE(funct6, vm, vs2, simm, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_vd_unmasked() then { handle_illegal(); return RETIRE_FAIL };
 
   let 'n = num_elem;
   let 'm = SEW;
@@ -772,7 +772,7 @@ function clause execute(FVVMTYPE(funct6, vm, vs2, vs1, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) | not(valid_fp_op(SEW, rm_3b)) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_fp_vd_unmasked(SEW, rm_3b) then { handle_illegal(); return RETIRE_FAIL };
   assert(SEW != 8);
 
   let 'n = num_elem;
@@ -836,7 +836,7 @@ function clause execute(FVFMTYPE(funct6, vm, vs2, rs1, vd)) = {
   let LMUL_pow = get_lmul_pow();
   let num_elem = get_num_elem(LMUL_pow, SEW);
 
-  if not(valid_vtype()) | not(valid_fp_op(SEW, rm_3b)) then { handle_illegal(); return RETIRE_FAIL };
+  if illegal_fp_vd_unmasked(SEW, rm_3b) then { handle_illegal(); return RETIRE_FAIL };
   assert(SEW != 8);
 
   let 'n = num_elem;