This commit adds support for the the amocas.{w,d,q} instructions behind
a new property to enable that instruction.

Signed-off-by: Rob Bradford <rbradf...@rivosinc.com>
---
 target/riscv/cpu.c                          |   4 +
 target/riscv/cpu.h                          |   1 +
 target/riscv/insn32.decode                  |   5 +
 target/riscv/insn_trans/trans_rvzacas.c.inc | 146 ++++++++++++++++++++
 target/riscv/translate.c                    |   1 +
 5 files changed, 157 insertions(+)
 create mode 100644 target/riscv/insn_trans/trans_rvzacas.c.inc

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index db0875fb43..e99833eb4a 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -82,6 +82,7 @@ static const struct isa_ext_data isa_edata_arr[] = {
     ISA_EXT_DATA_ENTRY(zicsr, PRIV_VERSION_1_10_0, ext_icsr),
     ISA_EXT_DATA_ENTRY(zifencei, PRIV_VERSION_1_10_0, ext_ifencei),
     ISA_EXT_DATA_ENTRY(zihintpause, PRIV_VERSION_1_10_0, ext_zihintpause),
+    ISA_EXT_DATA_ENTRY(zacas, PRIV_VERSION_1_12_0, ext_zacas),
     ISA_EXT_DATA_ENTRY(zawrs, PRIV_VERSION_1_12_0, ext_zawrs),
     ISA_EXT_DATA_ENTRY(zfh, PRIV_VERSION_1_11_0, ext_zfh),
     ISA_EXT_DATA_ENTRY(zfhmin, PRIV_VERSION_1_11_0, ext_zfhmin),
@@ -1604,6 +1605,9 @@ static Property riscv_cpu_extensions[] = {
     DEFINE_PROP_BOOL("x-zvfh", RISCVCPU, cfg.ext_zvfh, false),
     DEFINE_PROP_BOOL("x-zvfhmin", RISCVCPU, cfg.ext_zvfhmin, false),
 
+    /* Atomic CAS (Zacas) */
+    DEFINE_PROP_BOOL("x-zacas", RISCVCPU, cfg.ext_zacas, false),
+
     DEFINE_PROP_END_OF_LIST(),
 };
 
diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index de7e43126a..ac4d9e8e9c 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -436,6 +436,7 @@ struct RISCVCPUConfig {
     bool ext_smaia;
     bool ext_ssaia;
     bool ext_sscofpmf;
+    bool ext_zacas;
     bool rvv_ta_all_1s;
     bool rvv_ma_all_1s;
 
diff --git a/target/riscv/insn32.decode b/target/riscv/insn32.decode
index 73d5d1b045..97d17ee520 100644
--- a/target/riscv/insn32.decode
+++ b/target/riscv/insn32.decode
@@ -255,6 +255,11 @@ amomax_d   10100 . . ..... ..... 011 ..... 0101111 @atom_st
 amominu_d  11000 . . ..... ..... 011 ..... 0101111 @atom_st
 amomaxu_d  11100 . . ..... ..... 011 ..... 0101111 @atom_st
 
+# *** Zacas Extension
+amocas_w   00101 . . ..... ..... 010 ..... 0101111 @atom_st
+amocas_d   00101 . . ..... ..... 011 ..... 0101111 @atom_st
+amocas_q   00101 . . ..... ..... 100 ..... 0101111 @atom_st
+
 # *** RV32F Standard Extension ***
 flw        ............   ..... 010 ..... 0000111 @i
 fsw        .......  ..... ..... 010 ..... 0100111 @s
diff --git a/target/riscv/insn_trans/trans_rvzacas.c.inc 
b/target/riscv/insn_trans/trans_rvzacas.c.inc
new file mode 100644
index 0000000000..3f1b58ee8a
--- /dev/null
+++ b/target/riscv/insn_trans/trans_rvzacas.c.inc
@@ -0,0 +1,146 @@
+/*
+ * RISC-V translation routines for Zacas extension
+ *
+ * Copyright (c) 2023 Rivos Inc
+ *
+ * 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/>.
+ */
+
+#define REQUIRE_ZACAS(ctx) do {                 \
+    if (!ctx->cfg_ptr->ext_zacas) {             \
+        return false;                           \
+    }                                           \
+} while (0)
+
+static bool amocas_tl(DisasContext *ctx, arg_atomic *a, MemOp mop)
+{
+    TCGv retv = dest_gpr(ctx, a->rd);
+    TCGv addr = get_address(ctx, a->rs1, 0);
+    TCGv newv = get_gpr(ctx, a->rs2, EXT_ZERO);
+    TCGv cmpv = get_gpr(ctx, a->rd, EXT_ZERO);
+
+    decode_save_opc(ctx);
+    tcg_gen_atomic_cmpxchg_tl(retv, addr, cmpv, newv, ctx->mem_idx, mop);
+    gen_set_gpr(ctx, a->rd, retv);
+
+    return true;
+}
+
+#if TARGET_LONG_BITS == 32
+static bool trans_amocas_w(DisasContext *ctx, arg_amocas_w *a)
+{
+    REQUIRE_ZACAS(ctx);
+    return amocas_tl(ctx, a, MO_TESL | MO_ALIGN);
+}
+#else
+static bool trans_amocas_w(DisasContext *ctx, arg_amocas_w *a)
+{
+    REQUIRE_64BIT(ctx);
+    REQUIRE_ZACAS(ctx);
+    ctx->ol = MXL_RV32;
+    return amocas_tl(ctx, a, MO_TESL | MO_ALIGN);
+}
+#endif
+
+#if TARGET_LONG_BITS == 32
+static bool trans_amocas_d(DisasContext *ctx, arg_amocas_w *a)
+{
+    TCGv_i64 retv, newv, cmpv;
+    TCGv_i32 cmpv_l, cmpv_h, newv_l, newv_h;
+    TCGv addr;
+
+    REQUIRE_ZACAS(ctx);
+
+    if (a->rd % 2 == 1 || a->rs2 % 2 == 1) {
+        return false;
+    }
+
+    addr = get_address(ctx, a->rs1, 0);
+    cmpv_l = get_gpr(ctx, a->rd, 0);
+    cmpv_h = a->rd == 0 ? get_gpr(ctx, 0, 0) : get_gpr(ctx, a->rd + 1, 0);
+    cmpv = tcg_temp_new_i64();
+    tcg_gen_concat_i32_i64(cmpv, cmpv_l, cmpv_h);
+    newv_l = get_gpr(ctx, a->rs2, 0);
+    newv_h = a->rs2 == 0 ? get_gpr(ctx, 0, 0) : get_gpr(ctx, a->rs2 + 1, 0);
+    newv = tcg_temp_new_i64();
+    tcg_gen_concat_i32_i64(newv, newv_l, newv_h);
+    retv = tcg_temp_new_i64();
+
+    decode_save_opc(ctx);
+    tcg_gen_atomic_cmpxchg_i64(retv, addr, cmpv, newv, ctx->mem_idx,
+                               MO_TESQ | MO_ALIGN);
+
+    if (a->rd != 0) {
+        TCGv_i32 retv_l = tcg_temp_new_i32();
+        TCGv_i32 retv_h = tcg_temp_new_i32();
+        tcg_gen_extr_i64_i32(retv_l, retv_h, retv);
+        gen_set_gpr(ctx, a->rd, retv_l);
+        gen_set_gpr(ctx, a->rd + 1, retv_h);
+    }
+
+    return true;
+}
+#else
+static bool trans_amocas_d(DisasContext *ctx, arg_amocas_w *a)
+{
+    REQUIRE_64BIT(ctx);
+    REQUIRE_ZACAS(ctx);
+    return amocas_tl(ctx, a, MO_TESQ | MO_ALIGN);
+}
+#endif
+
+#if TARGET_LONG_BITS == 32
+static bool trans_amocas_q(DisasContext *ctx, arg_amocas_w *a)
+{
+    return false;
+}
+#else
+static bool trans_amocas_q(DisasContext *ctx, arg_amocas_w *a)
+{
+    TCGv_i128 retv, newv, cmpv;
+    TCGv_i64 cmpv_l, cmpv_h, newv_l, newv_h;
+    TCGv addr;
+
+    REQUIRE_64BIT(ctx);
+    REQUIRE_ZACAS(ctx);
+
+    if (a->rd % 2 == 1 || a->rs2 % 2 == 1) {
+        return false;
+    }
+
+    addr = get_address(ctx, a->rs1, 0);
+    cmpv_l = get_gpr(ctx, a->rd, 0);
+    cmpv_h = a->rd == 0 ? get_gpr(ctx, 0, 0) : get_gpr(ctx, a->rd + 1, 0);
+    cmpv = tcg_temp_new_i128();
+    tcg_gen_concat_i64_i128(cmpv, cmpv_l, cmpv_h);
+    newv_l = get_gpr(ctx, a->rs2, 0);
+    newv_h = a->rs2 == 0 ? get_gpr(ctx, 0, 0) : get_gpr(ctx, a->rs2 + 1, 0);
+    newv = tcg_temp_new_i128();
+    tcg_gen_concat_i64_i128(newv, newv_l, newv_h);
+    retv = tcg_temp_new_i128();
+
+    decode_save_opc(ctx);
+    tcg_gen_atomic_cmpxchg_i128(retv, addr, cmpv, newv, ctx->mem_idx,
+                                MO_TEUO | MO_ALIGN);
+
+    if (a->rd != 0) {
+        TCGv_i64 retv_l = tcg_temp_new_i64();
+        TCGv_i64 retv_h = tcg_temp_new_i64();
+        tcg_gen_extr_i128_i64(retv_l, retv_h, retv);
+        gen_set_gpr(ctx, a->rd, retv_l);
+        gen_set_gpr(ctx, a->rd + 1, retv_h);
+    }
+
+    return true;
+}
+#endif
diff --git a/target/riscv/translate.c b/target/riscv/translate.c
index 928da0d3f0..55438f5ebf 100644
--- a/target/riscv/translate.c
+++ b/target/riscv/translate.c
@@ -1074,6 +1074,7 @@ static uint32_t opcode_at(DisasContextBase *dcbase, 
target_ulong pc)
 #include "insn_trans/trans_rvv.c.inc"
 #include "insn_trans/trans_rvb.c.inc"
 #include "insn_trans/trans_rvzicond.c.inc"
+#include "insn_trans/trans_rvzacas.c.inc"
 #include "insn_trans/trans_rvzawrs.c.inc"
 #include "insn_trans/trans_rvzicbo.c.inc"
 #include "insn_trans/trans_rvzfh.c.inc"
-- 
2.40.1


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