RISC-V: FAIL:g++.dg/torture/vshuf-v[2|4]di.C -Os (execution test) on RV32

This patch fixs the issue of g++.dg/torture/vshuf-v2di.C
and g++.dg/torture/vshuf-v4di.C -Os execution failure with
-march=rv32gcv -mabi=ilp32d.

Consider the following code:
typedef unsigned long long V __attribute__((vector_size(16)));

.LC0: 0xc1c2c3c4c5c6c7c8

before this patch:

lui	a5,%hi(.LC0)
addi	a5,a5,%lo(.LC0)
lw	a6,4(a5)//0xc1c2c3c4
lw	a5,0(a5)//0xc5c6c7c8
vsetivli	zero,2,e64,m1,ta,mu
vmv.v.x	v2,a5//v2 is {0xffffffffc5c6c7c8, 0xffffffffc5c6c7c8}

after this patch:

lui	a5,%hi(.LC0)
addi	a5,a5,%lo(.LC0)
vsetivli	zero,2,e64,m1,ta,mu
vlse64.v	v2,0(a5),zero//v2 is {0xc1c2c3c4c5c6c7c8, 0xc1c2c3c4c5c6c7c8}

gcc/ChangeLog:

	* config/riscv/riscv-v.cc (sew64_scalar_helper): Bugfix.

1 files changed, 6 insertions, 1 deletions

diff --git a/gcc/config/riscv/riscv-v.cc b/gcc/config/riscv/riscv-v.cc
index dd659f9..87e5087 100644
--- a/gcc/config/riscv/riscv-v.cc
+++ b/gcc/config/riscv/riscv-v.cc
@@ -1728,7 +1728,12 @@ sew64_scalar_helper (rtx *operands, rtx *scalar_op, rtx vl,
     }
 
   if (CONST_INT_P (*scalar_op))
-    *scalar_op = force_reg (scalar_mode, *scalar_op);
+    {
+      if (maybe_gt (GET_MODE_SIZE (scalar_mode), GET_MODE_SIZE (Pmode)))
+	*scalar_op = force_const_mem (scalar_mode, *scalar_op);
+      else
+	*scalar_op = force_reg (scalar_mode, *scalar_op);
+    }
 
   rtx tmp = gen_reg_rtx (vector_mode);
   rtx ops[] = {tmp, *scalar_op};