target-tilegx: Add several helpers for instructions translation

The related instructions are exception, cntlz, cnttz, shufflebytes.
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NChen Gang <gang.chen.5i5j@gmail.com>
Message-Id: <BLU436-SMTP83F96FD8422BE49AFDC9DFB9660@phx.gbl>
[rth: Remove incorrect implementation of add_saturate.]
Signed-off-by: NRichard Henderson <rth@twiddle.net>

target-tilegx/helper.c

+/*
+ * QEMU TILE-Gx helpers
+ *
+ *  Copyright (c) 2015 Chen Gang
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see
+ * <http://www.gnu.org/licenses/lgpl-2.1.html>
+ */
+
+#include "cpu.h"
+#include "qemu-common.h"
+#include "exec/helper-proto.h"
+
+void helper_exception(CPUTLGState *env, uint32_t excp)
+{
+    CPUState *cs = CPU(tilegx_env_get_cpu(env));
+
+    cs->exception_index = excp;
+    cpu_loop_exit(cs);
+}
+
+uint64_t helper_cntlz(uint64_t arg)
+{
+    return clz64(arg);
+}
+
+uint64_t helper_cnttz(uint64_t arg)
+{
+    return ctz64(arg);
+}
+
+/*
+ * Functional Description
+ *     uint64_t a = rf[SrcA];
+ *     uint64_t b = rf[SrcB];
+ *     uint64_t d = rf[Dest];
+ *     uint64_t output = 0;
+ *     unsigned int counter;
+ *     for (counter = 0; counter < (WORD_SIZE / BYTE_SIZE); counter++)
+ *     {
+ *         int sel = getByte (b, counter) & 0xf;
+ *         uint8_t byte = (sel < 8) ? getByte (d, sel) : getByte (a, (sel - 8));
+ *         output = setByte (output, counter, byte);
+ *     }
+ *     rf[Dest] = output;
+ */
+uint64_t helper_shufflebytes(uint64_t dest, uint64_t srca, uint64_t srcb)
+{
+    uint64_t vdst = 0;
+    int count;
+
+    for (count = 0; count < 64; count += 8) {
+        uint64_t sel = srcb >> count;
+        uint64_t src = (sel & 8) ? srca : dest;
+        vdst |= extract64(src, (sel & 7) * 8, 8) << count;
+    }
+
+    return vdst;
+}

target-tilegx/helper.h

+DEF_HELPER_2(exception, noreturn, env, i32)
+DEF_HELPER_FLAGS_1(cntlz, TCG_CALL_NO_RWG_SE, i64, i64)
+DEF_HELPER_FLAGS_1(cnttz, TCG_CALL_NO_RWG_SE, i64, i64)
+DEF_HELPER_FLAGS_3(shufflebytes, TCG_CALL_NO_RWG_SE, i64, i64, i64, i64)