[Qemu-devel] [PATCH v2 17/29] target/riscv: Convert quadrant 1 of RVXC insns to decodetree

[Bastian Koppelmann <kbastian@mail.uni-paderborn.de>]

Signed-off-by: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>
Signed-off-by: Peer Adelt <peer.adelt@hni.uni-paderborn.de>
---
    v1 -> v2:
            - consistently return false for reserved cases instead of raising an
              exception
            - simplified trans_c_srli by Richard's suggestion
            - remove extract_cj() since its result isn't used

 target/riscv/insn16.decode              |  43 +++++++
 target/riscv/insn_trans/trans_rvc.inc.c | 149 +++++++++++++++++++++++-
 target/riscv/translate.c                | 118 +------------------
 3 files changed, 191 insertions(+), 119 deletions(-)

diff --git a/target/riscv/insn16.decode b/target/riscv/insn16.decode
index 558c0c41f0..29dade0fa1 100644
--- a/target/riscv/insn16.decode
+++ b/target/riscv/insn16.decode
@@ -22,28 +22,53 @@
 %rs2_3     2:3                !function=ex_rvc_register

 # Immediates:
+%imm_ci        12:s1 2:5
 %nzuimm_ciw    7:4 11:2 5:1 6:1   !function=ex_shift_2
 %uimm_cl_d     5:2 10:3           !function=ex_shift_3
 %uimm_cl_w     5:1 10:3 6:1       !function=ex_shift_2
+%imm_cb        12:s1 5:2 2:1 10:2 3:2 !function=ex_shift_1
+%imm_cj        12:s1 8:1 9:2 6:1 7:1 2:1 11:1 3:3 !function=ex_shift_1
+
+%nzuimm_6bit   12:1 2:5
+
+%imm_addi16sp  12:s1 3:2 5:1 2:1 6:1 !function=ex_shift_4
+%imm_lui       12:s1 2:5             !function=ex_shift_12
+


 # Argument sets:
 &cl               rs1 rd
 &cl_dw     uimm   rs1 rd
+&ci        imm        rd
 &ciw       nzuimm     rd
 &cs               rs1 rs2
 &cs_dw     uimm   rs1 rs2
+&cb        imm    rs1
+&cr               rd  rs2
+&c_j       imm
+&c_shift   shamt      rd
+

+&c_addi16sp_lui  imm_lui imm_addi16sp rd

 # Formats 16:
+@ci        ... . ..... .....  .. &ci     imm=%imm_ci                  %rd
 @ciw       ...   ........ ... .. &ciw    nzuimm=%nzuimm_ciw           rd=%rs2_3
 @cl_d      ... ... ... .. ... .. &cl_dw  uimm=%uimm_cl_d  rs1=%rs1_3  rd=%rs2_3
 @cl_w      ... ... ... .. ... .. &cl_dw  uimm=%uimm_cl_w  rs1=%rs1_3  rd=%rs2_3
 @cl        ... ... ... .. ... .. &cl                      rs1=%rs1_3  rd=%rs2_3
 @cs        ... ... ... .. ... .. &cs                      rs1=%rs1_3  rs2=%rs2_3
+@cs_2      ... ... ... .. ... .. &cr                      rd=%rs1_3   rs2=%rs2_3
 @cs_d      ... ... ... .. ... .. &cs_dw  uimm=%uimm_cl_d  rs1=%rs1_3  rs2=%rs2_3
 @cs_w      ... ... ... .. ... .. &cs_dw  uimm=%uimm_cl_w  rs1=%rs1_3  rs2=%rs2_3
+@cb        ... ... ... .. ... .. &cb     imm=%imm_cb      rs1=%rs1_3
+@cj        ...    ........... .. &c_j    imm=%imm_cj

+@c_addi16sp_lui ... .  ..... ..... .. &c_addi16sp_lui %imm_lui %imm_addi16sp %rd
+
+@c_shift        ... . .. ... ..... .. &c_shift rd=%rs1_3 shamt=%nzuimm_6bit
+
+@c_andi         ... . .. ... ..... .. &ci imm=%imm_ci rd=%rs1_3

 # *** RV64C Standard Extension (Quadrant 0) ***
 c_addi4spn        000    ........ ... 00 @ciw
@@ -53,3 +78,21 @@ c_flw_ld          011  --- ... -- ... 00 @cl    #Note: Must parse uimm manually
 c_fsd             101  ... ... .. ... 00 @cs_d
 c_sw              110  ... ... .. ... 00 @cs_w
 c_fsw_sd          111  --- ... -- ... 00 @cs    #Note: Must parse uimm manually
+
+# *** RV64C Standard Extension (Quadrant 1) ***
+c_addi            000 .  .....  ..... 01 @ci
+c_jal_addiw       001 .  .....  ..... 01 @ci #Note: parse rd and/or imm manually
+c_li              010 .  .....  ..... 01 @ci
+c_addi16sp_lui    011 .  .....  ..... 01 @c_addi16sp_lui # shares opc with C.LUI
+c_srli            100 . 00 ...  ..... 01 @c_shift
+c_srai            100 . 01 ...  ..... 01 @c_shift
+c_andi            100 . 10 ...  ..... 01 @c_andi
+c_sub             100 0 11 ... 00 ... 01 @cs_2
+c_xor             100 0 11 ... 01 ... 01 @cs_2
+c_or              100 0 11 ... 10 ... 01 @cs_2
+c_and             100 0 11 ... 11 ... 01 @cs_2
+c_subw            100 1 11 ... 00 ... 01 @cs_2
+c_addw            100 1 11 ... 01 ... 01 @cs_2
+c_j               101     ........... 01 @cj
+c_beqz            110  ... ...  ..... 01 @cb
+c_bnez            111  ... ...  ..... 01 @cb
diff --git a/target/riscv/insn_trans/trans_rvc.inc.c b/target/riscv/insn_trans/trans_rvc.inc.c
index a959f04421..dc7d9922f2 100644
--- a/target/riscv/insn_trans/trans_rvc.inc.c
+++ b/target/riscv/insn_trans/trans_rvc.inc.c
@@ -23,8 +23,7 @@ static bool trans_c_addi4spn(DisasContext *ctx, arg_c_addi4spn *a,
 {
     if (a->nzuimm == 0) {
         /* Reserved in ISA */
-        gen_exception_illegal(ctx);
-        return true;
+        return false;
     }
     arg_addi arg = { .rd = a->rd, .rs1 = 2, .imm = a->nzuimm };
     return trans_addi(ctx, &arg, insn);
@@ -87,3 +86,149 @@ static bool trans_c_fsw_sd(DisasContext *ctx, arg_c_fsw_sd *a, uint16_t insn)
     return trans_sd(ctx, &arg, insn);
 #endif
 }
+
+static bool trans_c_addi(DisasContext *ctx, arg_c_addi *a, uint16_t insn)
+{
+    if (a->imm == 0) {
+        /* Hint: insn is valid but does not affect state */
+        return true;
+    }
+    arg_addi arg = { .rd = a->rd, .rs1 = a->rd, .imm = a->imm };
+    return trans_addi(ctx, &arg, insn);
+}
+
+static bool trans_c_jal_addiw(DisasContext *ctx, arg_c_jal_addiw *a,
+        uint16_t insn)
+{
+#ifdef TARGET_RISCV32
+    /* C.JAL */
+    arg_jal arg = { .rd = 1, .imm = a->imm };
+    return trans_jal(ctx, &arg, insn);
+#else
+    /* C.ADDIW */
+    arg_addiw arg = { .rd = a->rd, .rs1 = a->rd, .imm = a->imm };
+    return trans_addiw(ctx, &arg, insn);
+#endif
+}
+
+static bool trans_c_li(DisasContext *ctx, arg_c_li *a, uint16_t insn)
+{
+    if (a->rd == 0) {
+        /* Hint: insn is valid but does not affect state */
+        return true;
+    }
+    arg_addi arg = { .rd = a->rd, .rs1 = 0, .imm = a->imm };
+    return trans_addi(ctx, &arg, insn);
+}
+
+static bool trans_c_addi16sp_lui(DisasContext *ctx, arg_c_addi16sp_lui *a,
+        uint16_t insn)
+{
+    if (a->rd == 2) {
+        /* C.ADDI16SP */
+        arg_addi arg = { .rd = 2, .rs1 = 2, .imm = a->imm_addi16sp };
+        return trans_addi(ctx, &arg, insn);
+    } else if (a->imm_lui != 0) {
+        /* C.LUI */
+        if (a->rd == 0) {
+            /* Hint: insn is valid but does not affect state */
+            return true;
+        }
+        arg_lui arg = { .rd = a->rd, .imm = a->imm_lui };
+        return trans_lui(ctx, &arg, insn);
+    }
+    return false;
+}
+
+static bool trans_c_srli(DisasContext *ctx, arg_c_srli *a, uint16_t insn)
+{
+    int shamt = a->shamt;
+    if (shamt == 0) {
+        /* For RV128 a shamt of 0 means a shift by 64 */
+        shamt = 64;
+    }
+    /* Ensure, that shamt[5] is zero for RV32 */
+    if (shamt >= TARGET_LONG_BITS) {
+        return false;
+    }
+
+    arg_srli arg = { .rd = a->rd, .rs1 = a->rd, .shamt = a->shamt };
+    return trans_srli(ctx, &arg, insn);
+}
+
+static bool trans_c_srai(DisasContext *ctx, arg_c_srai *a, uint16_t insn)
+{
+    if (a->shamt == 0) {
+        /* Reserved in ISA */
+        return false;
+    }
+#ifdef TARGET_RISCV32
+    /* Ensure, that shamt[5] is zero for RV32 */
+    if (a->shamt >= 32) {
+        return false;
+    }
+#endif
+
+    arg_srai arg = { .rd = a->rd, .rs1 = a->rd, .shamt = a->shamt };
+    return trans_srai(ctx, &arg, insn);
+}
+
+static bool trans_c_andi(DisasContext *ctx, arg_c_andi *a, uint16_t insn)
+{
+    arg_andi arg = { .rd = a->rd, .rs1 = a->rd, .imm = a->imm };
+    return trans_andi(ctx, &arg, insn);
+}
+
+static bool trans_c_sub(DisasContext *ctx, arg_c_sub *a, uint16_t insn)
+{
+    arg_sub arg = { .rd = a->rd, .rs1 = a->rd, .rs2 = a->rs2 };
+    return trans_sub(ctx, &arg, insn);
+}
+
+static bool trans_c_xor(DisasContext *ctx, arg_c_xor *a, uint16_t insn)
+{
+    arg_xor arg = { .rd = a->rd, .rs1 = a->rd, .rs2 = a->rs2 };
+    return trans_xor(ctx, &arg, insn);
+}
+
+static bool trans_c_or(DisasContext *ctx, arg_c_or *a, uint16_t insn)
+{
+    arg_or arg = { .rd = a->rd, .rs1 = a->rd, .rs2 = a->rs2 };
+    return trans_or(ctx, &arg, insn);
+}
+
+static bool trans_c_and(DisasContext *ctx, arg_c_and *a, uint16_t insn)
+{
+    arg_and arg = { .rd = a->rd, .rs1 = a->rd, .rs2 = a->rs2 };
+    return trans_and(ctx, &arg, insn);
+}
+
+static bool trans_c_subw(DisasContext *ctx, arg_c_subw *a, uint16_t insn)
+{
+    arg_subw arg = { .rd = a->rd, .rs1 = a->rd, .rs2 = a->rs2 };
+    return trans_subw(ctx, &arg, insn);
+}
+
+static bool trans_c_addw(DisasContext *ctx, arg_c_addw *a, uint16_t insn)
+{
+    arg_addw arg = { .rd = a->rd, .rs1 = a->rd, .rs2 = a->rs2 };
+    return trans_addw(ctx, &arg, insn);
+}
+
+static bool trans_c_j(DisasContext *ctx, arg_c_j *a, uint16_t insn)
+{
+    arg_jal arg = { .rd = 0, .imm = a->imm };
+    return trans_jal(ctx, &arg, insn);
+}
+
+static bool trans_c_beqz(DisasContext *ctx, arg_c_beqz *a, uint16_t insn)
+{
+    arg_beq arg = { .rs1 = a->rs1, .rs2 = 0, .imm = a->imm };
+    return trans_beq(ctx, &arg, insn);
+}
+
+static bool trans_c_bnez(DisasContext *ctx, arg_c_bnez *a, uint16_t insn)
+{
+    arg_bne arg = { .rs1 = a->rs1, .rs2 = 0, .imm = a->imm };
+    return trans_bne(ctx, &arg, insn);
+}
diff --git a/target/riscv/translate.c b/target/riscv/translate.c
index 8182946ee8..88aa355703 100644
--- a/target/riscv/translate.c
+++ b/target/riscv/translate.c
@@ -714,120 +714,6 @@ static void gen_system(CPURISCVState *env, DisasContext *ctx, uint32_t opc,
     }
 }

-static void decode_RV32_64C1(CPURISCVState *env, DisasContext *ctx)
-{
-    uint8_t funct3 = extract32(ctx->opcode, 13, 3);
-    uint8_t rd_rs1 = GET_C_RS1(ctx->opcode);
-    uint8_t rs1s, rs2s;
-    uint8_t funct2;
-
-    switch (funct3) {
-    case 0:
-        /* C.ADDI -> addi rd, rd, nzimm[5:0] */
-        gen_arith_imm(ctx, OPC_RISC_ADDI, rd_rs1, rd_rs1,
-                      GET_C_IMM(ctx->opcode));
-        break;
-    case 1:
-#if defined(TARGET_RISCV64)
-        /* C.ADDIW (RV64/128) -> addiw rd, rd, imm[5:0]*/
-        gen_arith_imm(ctx, OPC_RISC_ADDIW, rd_rs1, rd_rs1,
-                      GET_C_IMM(ctx->opcode));
-#else
-        /* C.JAL(RV32) -> jal x1, offset[11:1] */
-        gen_jal(env, ctx, 1, GET_C_J_IMM(ctx->opcode));
-#endif
-        break;
-    case 2:
-        /* C.LI -> addi rd, x0, imm[5:0]*/
-        gen_arith_imm(ctx, OPC_RISC_ADDI, rd_rs1, 0, GET_C_IMM(ctx->opcode));
-        break;
-    case 3:
-        if (rd_rs1 == 2) {
-            /* C.ADDI16SP -> addi x2, x2, nzimm[9:4]*/
-            gen_arith_imm(ctx, OPC_RISC_ADDI, 2, 2,
-                          GET_C_ADDI16SP_IMM(ctx->opcode));
-        } else if (rd_rs1 != 0) {
-            /* C.LUI (rs1/rd =/= {0,2}) -> lui rd, nzimm[17:12]*/
-            tcg_gen_movi_tl(cpu_gpr[rd_rs1],
-                            GET_C_IMM(ctx->opcode) << 12);
-        }
-        break;
-    case 4:
-        funct2 = extract32(ctx->opcode, 10, 2);
-        rs1s = GET_C_RS1S(ctx->opcode);
-        switch (funct2) {
-        case 0: /* C.SRLI(RV32) -> srli rd', rd', shamt[5:0] */
-            gen_arith_imm(ctx, OPC_RISC_SHIFT_RIGHT_I, rs1s, rs1s,
-                               GET_C_ZIMM(ctx->opcode));
-            /* C.SRLI64(RV128) */
-            break;
-        case 1:
-            /* C.SRAI -> srai rd', rd', shamt[5:0]*/
-            gen_arith_imm(ctx, OPC_RISC_SHIFT_RIGHT_I, rs1s, rs1s,
-                            GET_C_ZIMM(ctx->opcode) | 0x400);
-            /* C.SRAI64(RV128) */
-            break;
-        case 2:
-            /* C.ANDI -> andi rd', rd', imm[5:0]*/
-            gen_arith_imm(ctx, OPC_RISC_ANDI, rs1s, rs1s,
-                          GET_C_IMM(ctx->opcode));
-            break;
-        case 3:
-            funct2 = extract32(ctx->opcode, 5, 2);
-            rs2s = GET_C_RS2S(ctx->opcode);
-            switch (funct2) {
-            case 0:
-                /* C.SUB -> sub rd', rd', rs2' */
-                if (extract32(ctx->opcode, 12, 1) == 0) {
-                    gen_arith(ctx, OPC_RISC_SUB, rs1s, rs1s, rs2s);
-                }
-#if defined(TARGET_RISCV64)
-                else {
-                    gen_arith(ctx, OPC_RISC_SUBW, rs1s, rs1s, rs2s);
-                }
-#endif
-                break;
-            case 1:
-                /* C.XOR -> xor rs1', rs1', rs2' */
-                if (extract32(ctx->opcode, 12, 1) == 0) {
-                    gen_arith(ctx, OPC_RISC_XOR, rs1s, rs1s, rs2s);
-                }
-#if defined(TARGET_RISCV64)
-                else {
-                    /* C.ADDW (RV64/128) */
-                    gen_arith(ctx, OPC_RISC_ADDW, rs1s, rs1s, rs2s);
-                }
-#endif
-                break;
-            case 2:
-                /* C.OR -> or rs1', rs1', rs2' */
-                gen_arith(ctx, OPC_RISC_OR, rs1s, rs1s, rs2s);
-                break;
-            case 3:
-                /* C.AND -> and rs1', rs1', rs2' */
-                gen_arith(ctx, OPC_RISC_AND, rs1s, rs1s, rs2s);
-                break;
-            }
-            break;
-        }
-        break;
-    case 5:
-        /* C.J -> jal x0, offset[11:1]*/
-        gen_jal(env, ctx, 0, GET_C_J_IMM(ctx->opcode));
-        break;
-    case 6:
-        /* C.BEQZ -> beq rs1', x0, offset[8:1]*/
-        rs1s = GET_C_RS1S(ctx->opcode);
-        gen_branch(env, ctx, OPC_RISC_BEQ, rs1s, 0, GET_C_B_IMM(ctx->opcode));
-        break;
-    case 7:
-        /* C.BNEZ -> bne rs1', x0, offset[8:1]*/
-        rs1s = GET_C_RS1S(ctx->opcode);
-        gen_branch(env, ctx, OPC_RISC_BNE, rs1s, 0, GET_C_B_IMM(ctx->opcode));
-        break;
-    }
-}
-
 static void decode_RV32_64C2(CPURISCVState *env, DisasContext *ctx)
 {
     uint8_t rd, rs2;
@@ -911,9 +797,6 @@ static void decode_RV32_64C(CPURISCVState *env, DisasContext *ctx)
     uint8_t op = extract32(ctx->opcode, 0, 2);

     switch (op) {
-    case 1:
-        decode_RV32_64C1(env, ctx);
-        break;
     case 2:
         decode_RV32_64C2(env, ctx);
         break;
@@ -928,6 +811,7 @@ static void decode_RV32_64C(CPURISCVState *env, DisasContext *ctx)
 EX_SH(1)
 EX_SH(2)
 EX_SH(3)
+EX_SH(4)
 EX_SH(12)

 static int ex_rvc_register(int reg)
--
2.19.1