target/riscv: rvv-1.0: integer scalar move instructions

* Remove "vmv.s.x: dothing if rs1 == 0" constraint.
* Add vmv.x.s instruction.

Signed-off-by: Frank Chang <frank.chang@sifive.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20211210075704.23951-37-frank.chang@sifive.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

target/riscv/insn32.decode

@@ -634,8 +634,9 @@ vmsif_m         010100 . ..... 00011 010 ..... 1010111 @r2_vm
 vmsof_m         010100 . ..... 00010 010 ..... 1010111 @r2_vm
 viota_m         010100 . ..... 10000 010 ..... 1010111 @r2_vm
 vid_v           010100 . 00000 10001 010 ..... 1010111 @r1_vm
+vmv_x_s         010000 1 ..... 00000 010 ..... 1010111 @r2rd
+vmv_s_x         010000 1 00000 ..... 110 ..... 1010111 @r2
 vext_x_v        001100 1 ..... ..... 010 ..... 1010111 @r
-vmv_s_x         001101 1 00000 ..... 110 ..... 1010111 @r2
 vfmv_f_s        001100 1 ..... 00000 001 ..... 1010111 @r2rd
 vfmv_s_f        001101 1 00000 ..... 101 ..... 1010111 @r2
 vslideup_vx     001110 . ..... ..... 100 ..... 1010111 @r_vm

target/riscv/insn_trans/trans_rvv.c.inc

@@ -2978,27 +2978,54 @@ static void vec_element_storei(DisasContext *s, int vreg,
     store_element(val, cpu_env, endian_ofs(s, vreg, idx), s->sew);
 }
 
+/* vmv.x.s rd, vs2 # x[rd] = vs2[0] */
+static bool trans_vmv_x_s(DisasContext *s, arg_vmv_x_s *a)
+{
+    if (require_rvv(s) &&
+        vext_check_isa_ill(s)) {
+        TCGv_i64 t1;
+        TCGv dest;
+
+        t1 = tcg_temp_new_i64();
+        dest = tcg_temp_new();
+        /*
+         * load vreg and sign-extend to 64 bits,
+         * then truncate to XLEN bits before storing to gpr.
+         */
+        vec_element_loadi(s, t1, a->rs2, 0, true);
+        tcg_gen_trunc_i64_tl(dest, t1);
+        gen_set_gpr(s, a->rd, dest);
+        tcg_temp_free_i64(t1);
+        tcg_temp_free(dest);
+
+        return true;
+    }
+    return false;
+}
+
 /* vmv.s.x vd, rs1 # vd[0] = rs1 */
 static bool trans_vmv_s_x(DisasContext *s, arg_vmv_s_x *a)
 {
-    if (vext_check_isa_ill(s)) {
+    if (require_rvv(s) &&
+        vext_check_isa_ill(s)) {
         /* This instruction ignores LMUL and vector register groups */
-        int maxsz = s->vlen >> 3;
         TCGv_i64 t1;
+        TCGv s1;
         TCGLabel *over = gen_new_label();
 
         tcg_gen_brcondi_tl(TCG_COND_EQ, cpu_vl, 0, over);
-        tcg_gen_gvec_dup_imm(SEW64, vreg_ofs(s, a->rd), maxsz, maxsz, 0);
-        if (a->rs1 == 0) {
-            goto done;
-        }
 
         t1 = tcg_temp_new_i64();
-        tcg_gen_extu_tl_i64(t1, cpu_gpr[a->rs1]);
+
+        /*
+         * load gpr and sign-extend to 64 bits,
+         * then truncate to SEW bits when storing to vreg.
+         */
+        s1 = get_gpr(s, a->rs1, EXT_NONE);
+        tcg_gen_ext_tl_i64(t1, s1);
         vec_element_storei(s, a->rd, 0, t1);
         tcg_temp_free_i64(t1);
         mark_vs_dirty(s);
-    done:
         gen_set_label(over);
         return true;
     }