target/riscv: Add XVentanaCondOps custom extension

This adds the decoder and translation for the XVentanaCondOps custom
extension (vendor-defined by Ventana Micro Systems), which is
documented at https://github.com/ventanamicro/ventana-custom-extensions/releases/download/v1.0.0/ventana-custom-extensions-v1.0.0.pdf

This commit then also adds a guard-function (has_XVentanaCondOps_p)
and the decoder function to the table of decoders, enabling the
support for the XVentanaCondOps extension.

Signed-off-by: Philipp Tomsich <philipp.tomsich@vrull.eu>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20220202005249.3566542-7-philipp.tomsich@vrull.eu>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

target/riscv/XVentanaCondOps.decode

@@ -0,0 +1,25 @@
+#
+# RISC-V translation routines for the XVentanaCondOps extension
+#
+# Copyright (c) 2022 Dr. Philipp Tomsich, philipp.tomsich@vrull.eu
+#
+# SPDX-License-Identifier: LGPL-2.1-or-later
+#
+# Reference: VTx-family custom instructions
+#            Custom ISA extensions for Ventana Micro Systems RISC-V cores
+#            (https://github.com/ventanamicro/ventana-custom-extensions/releases/download/v1.0.0/ventana-custom-extensions-v1.0.0.pdf)
+
+# Fields
+%rs2  20:5
+%rs1  15:5
+%rd    7:5
+
+# Argument sets
+&r    rd rs1 rs2  !extern
+
+# Formats
+@r         .......  ..... ..... ... ..... ....... &r                %rs2 %rs1 %rd
+
+# *** RV64 Custom-3 Extension ***
+vt_maskc   0000000  ..... ..... 110 ..... 1111011 @r
+vt_maskcn  0000000  ..... ..... 111 ..... 1111011 @r

target/riscv/cpu.c

@@ -733,6 +733,9 @@ static Property riscv_cpu_properties[] = {
     DEFINE_PROP_BOOL("zbc", RISCVCPU, cfg.ext_zbc, true),
     DEFINE_PROP_BOOL("zbs", RISCVCPU, cfg.ext_zbs, true),
 
+    /* Vendor-specific custom extensions */
+    DEFINE_PROP_BOOL("xventanacondops", RISCVCPU, cfg.ext_XVentanaCondOps, false),
+
     /* These are experimental so mark with 'x-' */
     DEFINE_PROP_BOOL("x-j", RISCVCPU, cfg.ext_j, false),
     /* ePMP 0.9.3 */

target/riscv/cpu.h

@@ -329,6 +329,9 @@ struct RISCVCPUConfig {
     bool ext_zve32f;
     bool ext_zve64f;
 
+    /* Vendor-specific custom extensions */
+    bool ext_XVentanaCondOps;
+
     char *priv_spec;
     char *user_spec;
     char *bext_spec;

target/riscv/insn_trans/trans_xventanacondops.c.inc

@@ -0,0 +1,39 @@
+/*
+ * RISC-V translation routines for the XVentanaCondOps extension.
+ *
+ * Copyright (c) 2021-2022 VRULL GmbH.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2 or later, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+static bool gen_vt_condmask(DisasContext *ctx, arg_r *a, TCGCond cond)
+{
+    TCGv dest = dest_gpr(ctx, a->rd);
+    TCGv src1 = get_gpr(ctx, a->rs1, EXT_NONE);
+    TCGv src2 = get_gpr(ctx, a->rs2, EXT_NONE);
+
+    tcg_gen_movcond_tl(cond, dest, src2, ctx->zero, src1, ctx->zero);
+
+    gen_set_gpr(ctx, a->rd, dest);
+    return true;
+}
+
+static bool trans_vt_maskc(DisasContext *ctx, arg_r *a)
+{
+    return gen_vt_condmask(ctx, a, TCG_COND_NE);
+}
+
+static bool trans_vt_maskcn(DisasContext *ctx, arg_r *a)
+{
+    return gen_vt_condmask(ctx, a, TCG_COND_EQ);
+}

target/riscv/meson.build

@@ -4,6 +4,7 @@ dir = meson.current_source_dir()
 gen = [
   decodetree.process('insn16.decode', extra_args: ['--static-decode=decode_insn16', '--insnwidth=16']),
   decodetree.process('insn32.decode', extra_args: '--static-decode=decode_insn32'),
+  decodetree.process('XVentanaCondOps.decode', extra_args: '--static-decode=decode_XVentanaCodeOps'),
 ]
 
 riscv_ss = ss.source_set()

target/riscv/translate.c

@@ -116,6 +116,14 @@ static bool always_true_p(DisasContext *ctx  __attribute__((__unused__)))
     return true;
 }
 
+#define MATERIALISE_EXT_PREDICATE(ext)  \
+    static bool has_ ## ext ## _p(DisasContext *ctx)    \
+    { \
+        return ctx->cfg_ptr->ext_ ## ext ; \
+    }
+
+MATERIALISE_EXT_PREDICATE(XVentanaCondOps);
+
 #ifdef TARGET_RISCV32
 #define get_xl(ctx)    MXL_RV32
 #elif defined(CONFIG_USER_ONLY)
@@ -854,9 +862,12 @@ static uint32_t opcode_at(DisasContextBase *dcbase, target_ulong pc)
 #include "insn_trans/trans_rvb.c.inc"
 #include "insn_trans/trans_rvzfh.c.inc"
 #include "insn_trans/trans_privileged.c.inc"
+#include "insn_trans/trans_xventanacondops.c.inc"
 
 /* Include the auto-generated decoder for 16 bit insn */
 #include "decode-insn16.c.inc"
+/* Include decoders for factored-out extensions */
+#include "decode-XVentanaCondOps.c.inc"
 
 static void decode_opc(CPURISCVState *env, DisasContext *ctx, uint16_t opcode)
 {
@@ -869,6 +880,7 @@ static void decode_opc(CPURISCVState *env, DisasContext *ctx, uint16_t opcode)
         bool (*decode_func)(DisasContext *, uint32_t);
     } decoders[] = {
         { always_true_p,  decode_insn32 },
+        { has_XVentanaCondOps_p,  decode_XVentanaCodeOps },
     };
 
     /* Check for compressed insn */