[PULL 20/47] target/arm: Implement new VFP fp16 insn VMOVX

[Peter Maydell]

The fp16 extension includes a new instruction VMOVX, which copies the
upper 16 bits of a 32-bit source VFP register into the lower 16
bits of the destination and zeroes the high half of the destination.
Implement it.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200828183354.27913-21-peter.maydell@linaro.org
---
 target/arm/vfp-uncond.decode   |  3 +++
 target/arm/translate-vfp.c.inc | 25 +++++++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/target/arm/vfp-uncond.decode b/target/arm/vfp-uncond.decode
index 39dc8f6373a..8891ab3d549 100644
--- a/target/arm/vfp-uncond.decode
+++ b/target/arm/vfp-uncond.decode
@@ -75,5 +75,8 @@ VCVT        1111 1110 1.11 11 rm:2 .... 1010 op:1 1.0 .... \
 VCVT        1111 1110 1.11 11 rm:2 .... 1011 op:1 1.0 .... \
             vm=%vm_dp vd=%vd_sp sz=3
 
+VMOVX       1111 1110 1.11 0000 .... 1010 01 . 0 .... \
+            vd=%vd_sp vm=%vm_sp
+
 VINS        1111 1110 1.11 0000 .... 1010 11 . 0 .... \
             vd=%vd_sp vm=%vm_sp
diff --git a/target/arm/translate-vfp.c.inc b/target/arm/translate-vfp.c.inc
index bda3dd25136..4b26156eccc 100644
--- a/target/arm/translate-vfp.c.inc
+++ b/target/arm/translate-vfp.c.inc
@@ -3482,3 +3482,28 @@ static bool trans_VINS(DisasContext *s, arg_VINS *a)
     tcg_temp_free_i32(rd);
     return true;
 }
+
+static bool trans_VMOVX(DisasContext *s, arg_VINS *a)
+{
+    TCGv_i32 rm;
+
+    if (!dc_isar_feature(aa32_fp16_arith, s)) {
+        return false;
+    }
+
+    if (s->vec_len != 0 || s->vec_stride != 0) {
+        return false;
+    }
+
+    if (!vfp_access_check(s)) {
+        return true;
+    }
+
+    /* Set Vd to high half of Vm */
+    rm = tcg_temp_new_i32();
+    neon_load_reg32(rm, a->vm);
+    tcg_gen_shri_i32(rm, rm, 16);
+    neon_store_reg32(rm, a->vd);
+    tcg_temp_free_i32(rm);
+    return true;
+}
-- 
2.20.1