tcg: Add support for vector compare select

Perform a per-element conditional move.  This combination operation is
easier to implement on some host vector units than plain cmp+bitsel.
Omit the usual gvec interface, as this is intended to be used by
target-specific gvec expansion call-backs.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

8 files changed, 75 insertions, 0 deletions

diff --git a/tcg/README b/tcg/README
index 76057ab59fb..21fcdf737ff 100644
--- a/tcg/README
+++ b/tcg/README
@@ -631,6 +631,13 @@ E.g. VECL=1 -> 64 << 1 -> v128, and VECE=2 -> 1 << 2 -> i32.
 
   Bitwise select, v0 = (v2 & v1) | (v3 & ~v1), across the entire vector.
 
+* cmpsel_vec v0, c1, c2, v3, v4, cond
+
+  Select elements based on comparison results:
+  for (i = 0; i < n; ++i) {
+    v0[i] = (c1[i] cond c2[i]) ? v3[i] : v4[i].
+  }
+
 *********
 
 Note 1: Some shortcuts are defined when the last operand is known to be
diff --git a/tcg/aarch64/tcg-target.h b/tcg/aarch64/tcg-target.h
index 52ee66424f9..b4a9d36bbcb 100644
--- a/tcg/aarch64/tcg-target.h
+++ b/tcg/aarch64/tcg-target.h
@@ -141,6 +141,7 @@ typedef enum {
 #define TCG_TARGET_HAS_sat_vec          1
 #define TCG_TARGET_HAS_minmax_vec       1
 #define TCG_TARGET_HAS_bitsel_vec       0
+#define TCG_TARGET_HAS_cmpsel_vec       0
 
 #define TCG_TARGET_DEFAULT_MO (0)
 #define TCG_TARGET_HAS_MEMORY_BSWAP     1
diff --git a/tcg/i386/tcg-target.h b/tcg/i386/tcg-target.h
index 08a03864332..16a83a7f7bf 100644
--- a/tcg/i386/tcg-target.h
+++ b/tcg/i386/tcg-target.h
@@ -191,6 +191,7 @@ extern bool have_avx2;
 #define TCG_TARGET_HAS_sat_vec          1
 #define TCG_TARGET_HAS_minmax_vec       1
 #define TCG_TARGET_HAS_bitsel_vec       0
+#define TCG_TARGET_HAS_cmpsel_vec       0
 
 #define TCG_TARGET_deposit_i32_valid(ofs, len) \
     (((ofs) == 0 && (len) == 8) || ((ofs) == 8 && (len) == 8) || \
diff --git a/tcg/tcg-op-vec.c b/tcg/tcg-op-vec.c
index 99cbf29e0b0..a888c02df89 100644
--- a/tcg/tcg-op-vec.c
+++ b/tcg/tcg-op-vec.c
@@ -119,6 +119,11 @@ bool tcg_can_emit_vecop_list(const TCGOpcode *list,
                 continue;
             }
             break;
+        case INDEX_op_cmpsel_vec:
+            if (tcg_can_emit_vec_op(INDEX_op_cmp_vec, type, vece)) {
+                continue;
+            }
+            break;
         default:
             break;
         }
@@ -159,6 +164,20 @@ void vec_gen_4(TCGOpcode opc, TCGType type, unsigned vece,
     op->args[3] = c;
 }
 
+static void vec_gen_6(TCGOpcode opc, TCGType type, unsigned vece, TCGArg r,
+                      TCGArg a, TCGArg b, TCGArg c, TCGArg d, TCGArg e)
+{
+    TCGOp *op = tcg_emit_op(opc);
+    TCGOP_VECL(op) = type - TCG_TYPE_V64;
+    TCGOP_VECE(op) = vece;
+    op->args[0] = r;
+    op->args[1] = a;
+    op->args[2] = b;
+    op->args[3] = c;
+    op->args[4] = d;
+    op->args[5] = e;
+}
+
 static void vec_gen_op2(TCGOpcode opc, unsigned vece, TCGv_vec r, TCGv_vec a)
 {
     TCGTemp *rt = tcgv_vec_temp(r);
@@ -717,3 +736,43 @@ void tcg_gen_bitsel_vec(unsigned vece, TCGv_vec r, TCGv_vec a,
         tcg_temp_free_vec(t);
     }
 }
+
+void tcg_gen_cmpsel_vec(TCGCond cond, unsigned vece, TCGv_vec r,
+                        TCGv_vec a, TCGv_vec b, TCGv_vec c, TCGv_vec d)
+{
+    TCGTemp *rt = tcgv_vec_temp(r);
+    TCGTemp *at = tcgv_vec_temp(a);
+    TCGTemp *bt = tcgv_vec_temp(b);
+    TCGTemp *ct = tcgv_vec_temp(c);
+    TCGTemp *dt = tcgv_vec_temp(d);
+    TCGArg ri = temp_arg(rt);
+    TCGArg ai = temp_arg(at);
+    TCGArg bi = temp_arg(bt);
+    TCGArg ci = temp_arg(ct);
+    TCGArg di = temp_arg(dt);
+    TCGType type = rt->base_type;
+    const TCGOpcode *hold_list;
+    int can;
+
+    tcg_debug_assert(at->base_type >= type);
+    tcg_debug_assert(bt->base_type >= type);
+    tcg_debug_assert(ct->base_type >= type);
+    tcg_debug_assert(dt->base_type >= type);
+
+    tcg_assert_listed_vecop(INDEX_op_cmpsel_vec);
+    hold_list = tcg_swap_vecop_list(NULL);
+    can = tcg_can_emit_vec_op(INDEX_op_cmpsel_vec, type, vece);
+
+    if (can > 0) {
+        vec_gen_6(INDEX_op_cmpsel_vec, type, vece, ri, ai, bi, ci, di, cond);
+    } else if (can < 0) {
+        tcg_expand_vec_op(INDEX_op_cmpsel_vec, type, vece,
+                          ri, ai, bi, ci, di, cond);
+    } else {
+        TCGv_vec t = tcg_temp_new_vec(type);
+        tcg_gen_cmp_vec(cond, vece, t, a, b);
+        tcg_gen_bitsel_vec(vece, r, t, c, d);
+        tcg_temp_free_vec(t);
+    }
+    tcg_swap_vecop_list(hold_list);
+}
diff --git a/tcg/tcg-op.h b/tcg/tcg-op.h
index 268860ed2f6..2d4dd5cd7de 100644
--- a/tcg/tcg-op.h
+++ b/tcg/tcg-op.h
@@ -1002,6 +1002,8 @@ void tcg_gen_cmp_vec(TCGCond cond, unsigned vece, TCGv_vec r,
 
 void tcg_gen_bitsel_vec(unsigned vece, TCGv_vec r, TCGv_vec a,
                         TCGv_vec b, TCGv_vec c);
+void tcg_gen_cmpsel_vec(TCGCond cond, unsigned vece, TCGv_vec r,
+                        TCGv_vec a, TCGv_vec b, TCGv_vec c, TCGv_vec d);
 
 void tcg_gen_ld_vec(TCGv_vec r, TCGv_ptr base, TCGArg offset);
 void tcg_gen_st_vec(TCGv_vec r, TCGv_ptr base, TCGArg offset);
diff --git a/tcg/tcg-opc.h b/tcg/tcg-opc.h
index c05b71427c5..c7d971fa3d1 100644
--- a/tcg/tcg-opc.h
+++ b/tcg/tcg-opc.h
@@ -257,6 +257,7 @@ DEF(sarv_vec, 1, 2, 0, IMPLVEC | IMPL(TCG_TARGET_HAS_shv_vec))
 DEF(cmp_vec, 1, 2, 1, IMPLVEC)
 
 DEF(bitsel_vec, 1, 3, 0, IMPLVEC | IMPL(TCG_TARGET_HAS_bitsel_vec))
+DEF(cmpsel_vec, 1, 4, 1, IMPLVEC | IMPL(TCG_TARGET_HAS_cmpsel_vec))
 
 DEF(last_generic, 0, 0, 0, TCG_OPF_NOT_PRESENT)
 
diff --git a/tcg/tcg.c b/tcg/tcg.c
index 5d947dbcb0b..02a26801693 100644
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -1648,6 +1648,8 @@ bool tcg_op_supported(TCGOpcode op)
         return have_vec && TCG_TARGET_HAS_minmax_vec;
     case INDEX_op_bitsel_vec:
         return have_vec && TCG_TARGET_HAS_bitsel_vec;
+    case INDEX_op_cmpsel_vec:
+        return have_vec && TCG_TARGET_HAS_cmpsel_vec;
 
     default:
         tcg_debug_assert(op > INDEX_op_last_generic && op < NB_OPS);
@@ -2028,6 +2030,7 @@ static void tcg_dump_ops(TCGContext *s, bool have_prefs)
             case INDEX_op_setcond_i64:
             case INDEX_op_movcond_i64:
             case INDEX_op_cmp_vec:
+            case INDEX_op_cmpsel_vec:
                 if (op->args[k] < ARRAY_SIZE(cond_name)
                     && cond_name[op->args[k]]) {
                     col += qemu_log(",%s", cond_name[op->args[k++]]);
diff --git a/tcg/tcg.h b/tcg/tcg.h
index 72f9f6c70ba..21cd6f1249c 100644
--- a/tcg/tcg.h
+++ b/tcg/tcg.h
@@ -188,6 +188,7 @@ typedef uint64_t TCGRegSet;
 #define TCG_TARGET_HAS_sat_vec          0
 #define TCG_TARGET_HAS_minmax_vec       0
 #define TCG_TARGET_HAS_bitsel_vec       0
+#define TCG_TARGET_HAS_cmpsel_vec       0
 #else
 #define TCG_TARGET_MAYBE_vec            1
 #endif