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Re: [Qemu-devel] [PATCH v3 02/35] target/riscv: Activate decodetree and


From: Alistair
Subject: Re: [Qemu-devel] [PATCH v3 02/35] target/riscv: Activate decodetree and implemnt LUI & AUIPC
Date: Wed, 31 Oct 2018 13:20:46 -0700
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1

On 10/31/18 6:19 AM, Bastian Koppelmann wrote:
for now only LUI & AUIPC are decoded and translated. If decodetree fails, we
fall back to the old decoder.

Reviewed-by: Richard Henderson <address@hidden>
Signed-off-by: Bastian Koppelmann <address@hidden>
Signed-off-by: Peer Adelt <address@hidden>

Acked-by: Alistair Francis <address@hidden>

Alistair

---
v2 -> v3:
     - ex_shift_amount returns int
     - dropped insn argument of trans_foo functions

  target/riscv/Makefile.objs              | 10 +++++++
  target/riscv/insn32.decode              | 30 +++++++++++++++++++++
  target/riscv/insn_trans/trans_rvi.inc.c | 35 +++++++++++++++++++++++++
  target/riscv/translate.c                | 31 ++++++++++++----------
  4 files changed, 92 insertions(+), 14 deletions(-)
  create mode 100644 target/riscv/insn32.decode
  create mode 100644 target/riscv/insn_trans/trans_rvi.inc.c

diff --git a/target/riscv/Makefile.objs b/target/riscv/Makefile.objs
index fcc5d34c1f..ee995b3fc7 100644
--- a/target/riscv/Makefile.objs
+++ b/target/riscv/Makefile.objs
@@ -1 +1,11 @@
  obj-y += translate.o op_helper.o cpu_helper.o cpu.o fpu_helper.o gdbstub.o 
pmp.o
+
+DECODETREE = $(SRC_PATH)/scripts/decodetree.py
+
+target/riscv/decode_insn32.inc.c: \
+  $(SRC_PATH)/target/riscv/insn32.decode $(DECODETREE)
+       $(call quiet-command, \
+         $(PYTHON) $(DECODETREE) -o $@ --decode decode_insn32 $<, \
+         "GEN", $(TARGET_DIR)$@)
+
+target/riscv/translate.o: target/riscv/decode_insn32.inc.c
diff --git a/target/riscv/insn32.decode b/target/riscv/insn32.decode
new file mode 100644
index 0000000000..44d4e922b6
--- /dev/null
+++ b/target/riscv/insn32.decode
@@ -0,0 +1,30 @@
+#
+# RISC-V translation routines for the RVXI Base Integer Instruction Set.
+#
+# Copyright (c) 2018 Peer Adelt, address@hidden
+#                    Bastian Koppelmann, address@hidden
+#
+# 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/>.
+
+# Fields:
+%rd        7:5
+
+# immediates:
+%imm_u    12:s20                 !function=ex_shift_12
+
+# Formats 32:
address@hidden       ....................      ..... .......         imm=%imm_u 
         %rd
+
+# *** RV32I Base Instruction Set ***
+lui      ....................       ..... 0110111 @u
+auipc    ....................       ..... 0010111 @u
diff --git a/target/riscv/insn_trans/trans_rvi.inc.c 
b/target/riscv/insn_trans/trans_rvi.inc.c
new file mode 100644
index 0000000000..9885a8d275
--- /dev/null
+++ b/target/riscv/insn_trans/trans_rvi.inc.c
@@ -0,0 +1,35 @@
+/*
+ * RISC-V translation routines for the RVXI Base Integer Instruction Set.
+ *
+ * Copyright (c) 2016-2017 Sagar Karandikar, address@hidden
+ * Copyright (c) 2018 Peer Adelt, address@hidden
+ *                    Bastian Koppelmann, address@hidden
+ *
+ * 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 trans_lui(DisasContext *ctx, arg_lui *a)
+{
+    if (a->rd != 0) {
+        tcg_gen_movi_tl(cpu_gpr[a->rd], a->imm);
+    }
+    return true;
+}
+
+static bool trans_auipc(DisasContext *ctx, arg_auipc *a)
+{
+    if (a->rd != 0) {
+        tcg_gen_movi_tl(cpu_gpr[a->rd], a->imm + ctx->base.pc_next);
+    }
+    return true;
+}
diff --git a/target/riscv/translate.c b/target/riscv/translate.c
index e81b9f097e..ba57cb29f5 100644
--- a/target/riscv/translate.c
+++ b/target/riscv/translate.c
@@ -1667,6 +1667,19 @@ static void decode_RV32_64C(CPURISCVState *env, 
DisasContext *ctx)
      }
  }
+#define EX_SH(amount) \
+    static int ex_shift_##amount(int imm) \
+    {                                         \
+        return imm << amount;                 \
+    }
+EX_SH(12)
+
+bool decode_insn32(DisasContext *ctx, uint32_t insn);
+/* Include the auto-generated decoder for 32 bit insn */
+#include "decode_insn32.inc.c"
+/* Include insn module translation function */
+#include "insn_trans/trans_rvi.inc.c"
+
  static void decode_RV32_64G(CPURISCVState *env, DisasContext *ctx)
  {
      int rs1;
@@ -1687,19 +1700,6 @@ static void decode_RV32_64G(CPURISCVState *env, 
DisasContext *ctx)
      imm = GET_IMM(ctx->opcode);
switch (op) {
-    case OPC_RISC_LUI:
-        if (rd == 0) {
-            break; /* NOP */
-        }
-        tcg_gen_movi_tl(cpu_gpr[rd], sextract64(ctx->opcode, 12, 20) << 12);
-        break;
-    case OPC_RISC_AUIPC:
-        if (rd == 0) {
-            break; /* NOP */
-        }
-        tcg_gen_movi_tl(cpu_gpr[rd], (sextract64(ctx->opcode, 12, 20) << 12) +
-               ctx->base.pc_next);
-        break;
      case OPC_RISC_JAL:
          imm = GET_JAL_IMM(ctx->opcode);
          gen_jal(env, ctx, rd, imm);
@@ -1802,7 +1802,10 @@ static void decode_opc(DisasContext *ctx)
          }
      } else {
          ctx->pc_succ_insn = ctx->base.pc_next + 4;
-        decode_RV32_64G(ctx->env, ctx);
+        if (!decode_insn32(ctx, ctx->opcode)) {
+            /* fallback to old decoder */
+            decode_RV32_64G(ctx->env, ctx);
+        }
      }
  }



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