target/arm: Implement SVE vector splice (predicated)

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20180613015641.5667-10-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 37 insertions, 0 deletions

diff --git a/target/arm/sve_helper.c b/target/arm/sve_helper.c
index 4017b9eed1..8da7baad76 100644
--- a/target/arm/sve_helper.c
+++ b/target/arm/sve_helper.c
@@ -2109,3 +2109,40 @@ int32_t HELPER(sve_last_active_element)(void *vg, uint32_t pred_desc)
 
     return last_active_element(vg, DIV_ROUND_UP(oprsz, 8), esz);
 }
+
+void HELPER(sve_splice)(void *vd, void *vn, void *vm, void *vg, uint32_t desc)
+{
+    intptr_t opr_sz = simd_oprsz(desc) / 8;
+    int esz = simd_data(desc);
+    uint64_t pg, first_g, last_g, len, mask = pred_esz_masks[esz];
+    intptr_t i, first_i, last_i;
+    ARMVectorReg tmp;
+
+    first_i = last_i = 0;
+    first_g = last_g = 0;
+
+    /* Find the extent of the active elements within VG.  */
+    for (i = QEMU_ALIGN_UP(opr_sz, 8) - 8; i >= 0; i -= 8) {
+        pg = *(uint64_t *)(vg + i) & mask;
+        if (pg) {
+            if (last_g == 0) {
+                last_g = pg;
+                last_i = i;
+            }
+            first_g = pg;
+            first_i = i;
+        }
+    }
+
+    len = 0;
+    if (first_g != 0) {
+        first_i = first_i * 8 + ctz64(first_g);
+        last_i = last_i * 8 + 63 - clz64(last_g);
+        len = last_i - first_i + (1 << esz);
+        if (vd == vm) {
+            vm = memcpy(&tmp, vm, opr_sz * 8);
+        }
+        swap_memmove(vd, vn + first_i, len);
+    }
+    swap_memmove(vd + len, vm, opr_sz * 8 - len);
+}