diff --git a/gcc/config/riscv/riscv-modes.def b/gcc/config/riscv/riscv-modes.def
index 110bddce851..4cf7cf8b1c6 100644
--- a/gcc/config/riscv/riscv-modes.def
+++ b/gcc/config/riscv/riscv-modes.def
@@ -64,13 +64,13 @@ ADJUST_ALIGNMENT (VNx16BI, 1);
 ADJUST_ALIGNMENT (VNx32BI, 1);
 ADJUST_ALIGNMENT (VNx64BI, 1);
 
-ADJUST_BYTESIZE (VNx1BI, riscv_vector_chunks * riscv_bytes_per_vector_chunk);
-ADJUST_BYTESIZE (VNx2BI, riscv_vector_chunks * riscv_bytes_per_vector_chunk);
-ADJUST_BYTESIZE (VNx4BI, riscv_vector_chunks * riscv_bytes_per_vector_chunk);
-ADJUST_BYTESIZE (VNx8BI, riscv_vector_chunks * riscv_bytes_per_vector_chunk);
-ADJUST_BYTESIZE (VNx16BI, riscv_vector_chunks * riscv_bytes_per_vector_chunk);
-ADJUST_BYTESIZE (VNx32BI, riscv_vector_chunks * riscv_bytes_per_vector_chunk);
-ADJUST_BYTESIZE (VNx64BI, riscv_v_adjust_nunits (VNx64BImode, 8));
+ADJUST_BYTESIZE (VNx1BI, riscv_v_adjust_bytesize (VNx1BImode, 1));
+ADJUST_BYTESIZE (VNx2BI, riscv_v_adjust_bytesize (VNx2BImode, 1));
+ADJUST_BYTESIZE (VNx4BI, riscv_v_adjust_bytesize (VNx4BImode, 1));
+ADJUST_BYTESIZE (VNx8BI, riscv_v_adjust_bytesize (VNx8BImode, 1));
+ADJUST_BYTESIZE (VNx16BI, riscv_v_adjust_bytesize (VNx16BImode, 2));
+ADJUST_BYTESIZE (VNx32BI, riscv_v_adjust_bytesize (VNx32BImode, 4));
+ADJUST_BYTESIZE (VNx64BI, riscv_v_adjust_bytesize (VNx64BImode, 8));
 
 ADJUST_PRECISION (VNx1BI, riscv_v_adjust_precision (VNx1BImode, 1));
 ADJUST_PRECISION (VNx2BI, riscv_v_adjust_precision (VNx2BImode, 2));
diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index e7b7d87cebc..428fbb28fae 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -1003,6 +1003,28 @@ riscv_v_adjust_nunits (machine_mode mode, int scale)
   return scale;
 }
 
+/* Call from ADJUST_BYTESIZE in riscv-modes.def.  Return the correct
+   BYTE size for corresponding machine_mode.  */
+
+poly_int64
+riscv_v_adjust_bytesize (machine_mode mode, int scale)
+{
+  if (riscv_v_ext_vector_mode_p (mode))
+  {
+    poly_uint16 mode_size = GET_MODE_SIZE (mode);
+
+    if (maybe_eq (mode_size, (uint16_t)-1))
+      mode_size = riscv_vector_chunks * scale;
+
+    if (known_gt (mode_size, BYTES_PER_RISCV_VECTOR))
+      mode_size = BYTES_PER_RISCV_VECTOR;
+
+    return mode_size;
+  }
+
+  return scale;
+}
+
 /* Call from ADJUST_PRECISION in riscv-modes.def.  Return the correct
    PRECISION size for corresponding machine_mode.  */
 
diff --git a/gcc/config/riscv/riscv.h b/gcc/config/riscv/riscv.h
index 15b9317a8ce..66fb07d6652 100644
--- a/gcc/config/riscv/riscv.h
+++ b/gcc/config/riscv/riscv.h
@@ -1026,6 +1026,7 @@ extern unsigned riscv_bytes_per_vector_chunk;
 extern poly_uint16 riscv_vector_chunks;
 extern poly_int64 riscv_v_adjust_nunits (enum machine_mode, int);
 extern poly_int64 riscv_v_adjust_precision (enum machine_mode, int);
+extern poly_int64 riscv_v_adjust_bytesize (enum machine_mode, int);
 /* The number of bits and bytes in a RVV vector.  */
 #define BITS_PER_RISCV_VECTOR (poly_uint16 (riscv_vector_chunks * riscv_bytes_per_vector_chunk * 8))
 #define BYTES_PER_RISCV_VECTOR (poly_uint16 (riscv_vector_chunks * riscv_bytes_per_vector_chunk))
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/pr108185-1.c b/gcc/testsuite/gcc.target/riscv/rvv/base/pr108185-1.c
index e70960c5b6d..c3d0b10271a 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/base/pr108185-1.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/pr108185-1.c
@@ -65,4 +65,4 @@ test_vbool1_then_vbool64(int8_t * restrict in, int8_t * restrict out) {
 /* { dg-final { scan-assembler-times {vsetvli\s+[a-x][0-9]+,\s*zero,\s*e8,\s*mf4,\s*ta,\s*ma} 1 } } */
 /* { dg-final { scan-assembler-times {vsetvli\s+[a-x][0-9]+,\s*zero,\s*e8,\s*mf8,\s*ta,\s*ma} 1 } } */
 /* { dg-final { scan-assembler-times {vlm\.v\s+v[0-9]+,\s*0\([a-x][0-9]+\)} 12 } } */
-/* { dg-final { scan-assembler-times {vsm\.v\s+v[0-9]+,\s*0\([a-x][0-9]+\)} 18 } } */
+/* { dg-final { scan-assembler-times {vsm\.v\s+v[0-9]+,\s*0\([a-x][0-9]+\)} 12 } } */
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/pr108185-2.c b/gcc/testsuite/gcc.target/riscv/rvv/base/pr108185-2.c
index dcc7a644a88..bd13ba916da 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/base/pr108185-2.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/pr108185-2.c
@@ -65,4 +65,4 @@ test_vbool2_then_vbool64(int8_t * restrict in, int8_t * restrict out) {
 /* { dg-final { scan-assembler-times {vsetvli\s+[a-x][0-9]+,\s*zero,\s*e8,\s*mf4,\s*ta,\s*ma} 1 } } */
 /* { dg-final { scan-assembler-times {vsetvli\s+[a-x][0-9]+,\s*zero,\s*e8,\s*mf8,\s*ta,\s*ma} 1 } } */
 /* { dg-final { scan-assembler-times {vlm\.v\s+v[0-9]+,\s*0\([a-x][0-9]+\)} 12 } } */
-/* { dg-final { scan-assembler-times {vsm\.v\s+v[0-9]+,\s*0\([a-x][0-9]+\)} 17 } } */
+/* { dg-final { scan-assembler-times {vsm\.v\s+v[0-9]+,\s*0\([a-x][0-9]+\)} 12 } } */
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/pr108185-3.c b/gcc/testsuite/gcc.target/riscv/rvv/base/pr108185-3.c
index 3af0513e006..99928f7b1cc 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/base/pr108185-3.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/pr108185-3.c
@@ -65,4 +65,4 @@ test_vbool4_then_vbool64(int8_t * restrict in, int8_t * restrict out) {
 /* { dg-final { scan-assembler-times {vsetvli\s+[a-x][0-9]+,\s*zero,\s*e8,\s*mf4,\s*ta,\s*ma} 1 } } */
 /* { dg-final { scan-assembler-times {vsetvli\s+[a-x][0-9]+,\s*zero,\s*e8,\s*mf8,\s*ta,\s*ma} 1 } } */
 /* { dg-final { scan-assembler-times {vlm\.v\s+v[0-9]+,\s*0\([a-x][0-9]+\)} 12 } } */
-/* { dg-final { scan-assembler-times {vsm\.v\s+v[0-9]+,\s*0\([a-x][0-9]+\)} 16 } } */
+/* { dg-final { scan-assembler-times {vsm\.v\s+v[0-9]+,\s*0\([a-x][0-9]+\)} 12 } } */
