target-arm: A64: Add support for floating point cond select

This adds decoding support for C3.6.24 FP conditional select.
Signed-off-by: NClaudio Fontana <claudio.fontana@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NRichard Henderson <rth@twiddle.net>

target-arm/translate-a64.c

@@ -3304,6 +3304,20 @@ static void disas_fp_ccomp(DisasContext *s, uint32_t insn)
     }
 }
 
+/* copy src FP register to dst FP register; type specifies single or double */
+static void gen_mov_fp2fp(DisasContext *s, int type, int dst, int src)
+{
+    if (type) {
+        TCGv_i64 v = read_fp_dreg(s, src);
+        write_fp_dreg(s, dst, v);
+        tcg_temp_free_i64(v);
+    } else {
+        TCGv_i32 v = read_fp_sreg(s, src);
+        write_fp_sreg(s, dst, v);
+        tcg_temp_free_i32(v);
+    }
+}
+
 /* C3.6.24 Floating point conditional select
  *   31  30  29 28       24 23  22  21 20  16 15  12 11 10 9    5 4    0
  * +---+---+---+-----------+------+---+------+------+-----+------+------+
@@ -3312,7 +3326,36 @@ static void disas_fp_ccomp(DisasContext *s, uint32_t insn)
  */
 static void disas_fp_csel(DisasContext *s, uint32_t insn)
 {
-    unsupported_encoding(s, insn);
+    unsigned int mos, type, rm, cond, rn, rd;
+    int label_continue = -1;
+
+    mos = extract32(insn, 29, 3);
+    type = extract32(insn, 22, 2); /* 0 = single, 1 = double */
+    rm = extract32(insn, 16, 5);
+    cond = extract32(insn, 12, 4);
+    rn = extract32(insn, 5, 5);
+    rd = extract32(insn, 0, 5);
+
+    if (mos || type > 1) {
+        unallocated_encoding(s);
+        return;
+    }
+
+    if (cond < 0x0e) { /* not always */
+        int label_match = gen_new_label();
+        label_continue = gen_new_label();
+        arm_gen_test_cc(cond, label_match);
+        /* nomatch: */
+        gen_mov_fp2fp(s, type, rd, rm);
+        tcg_gen_br(label_continue);
+        gen_set_label(label_match);
+    }
+
+    gen_mov_fp2fp(s, type, rd, rn);
+
+    if (cond < 0x0e) { /* continue */
+        gen_set_label(label_continue);
+    }
 }
 
 /* C3.6.25 Floating point data-processing (1 source)