xref: /gem5/src/arch/riscv/isa/decoder.isa

// -*- mode:c++ -*-

// Copyright (c) 2015 RISC-V Foundation
// Copyright (c) 2016 The University of Virginia
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met: redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer;
// redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution;
// neither the name of the copyright holders nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Authors: Alec Roelke

////////////////////////////////////////////////////////////////////
//
// The RISC-V ISA decoder
//

decode OPCODE default Unknown::unknown() {
    0x03: decode FUNCT3 {
        format Load {
            0x0: lb({{
                Rd_sd = Mem_sb;
            }});
            0x1: lh({{
                Rd_sd = Mem_sh;
            }});
            0x2: lw({{
                Rd_sd = Mem_sw;
            }});
            0x3: ld({{
                Rd_sd = Mem_sd;
            }});
            0x4: lbu({{
                Rd = Mem_ub;
            }});
            0x5: lhu({{
                Rd = Mem_uh;
            }});
            0x6: lwu({{
                Rd = Mem_uw;
            }});
        }
    }

    0x0f: decode FUNCT3 {
        format IOp {
            0x0: fence({{
            }}, IsNonSpeculative, IsMemBarrier, No_OpClass);
            0x1: fence_i({{
            }}, IsNonSpeculative, IsSerializeAfter, No_OpClass);
        }
    }

    0x13: decode FUNCT3 {
        format IOp {
            0x0: addi({{
                Rd_sd = Rs1_sd + imm;
            }});
            0x1: slli({{
                Rd = Rs1 << SHAMT6;
            }});
            0x2: slti({{
                Rd = (Rs1_sd < imm) ? 1 : 0;
            }});
            0x3: sltiu({{
                Rd = (Rs1 < (uint64_t)imm) ? 1 : 0;
            }});
            0x4: xori({{
                Rd = Rs1 ^ (uint64_t)imm;
            }});
            0x5: decode SRTYPE {
                0x0: srli({{
                    Rd = Rs1 >> SHAMT6;
                }});
                0x1: srai({{
                    Rd_sd = Rs1_sd >> SHAMT6;
                }});
            }
            0x6: ori({{
                Rd = Rs1 | (uint64_t)imm;
            }});
            0x7: andi({{
                Rd = Rs1 & (uint64_t)imm;
            }});
        }
    }

    0x17: UOp::auipc({{
        Rd = PC + imm;
    }});

    0x1b: decode FUNCT3 {
        format IOp {
            0x0: addiw({{
                Rd_sd = (int32_t)Rs1 + (int32_t)imm;
            }});
            0x1: slliw({{
                Rd_sd = Rs1_sw << SHAMT5;
            }});
            0x5: decode SRTYPE {
                0x0: srliw({{
                    Rd = Rs1_uw >> SHAMT5;
                }});
                0x1: sraiw({{
                    Rd_sd = Rs1_sw >> SHAMT5;
                }});
            }
        }
    }

    0x23: decode FUNCT3 {
        format Store {
            0x0: sb({{
                Mem_ub = Rs2_ub;
            }});
            0x1: sh({{
                Mem_uh = Rs2_uh;
            }});
            0x2: sw({{
                Mem_uw = Rs2_uw;
            }});
            0x3: sd({{
                Mem_ud = Rs2_ud;
            }});
        }
    }

    0x33: decode FUNCT3 {
        format ROp {
            0x0: decode FUNCT7 {
                0x0: add({{
                    Rd = Rs1_sd + Rs2_sd;
                }});
                0x1: mul({{
                    Rd = Rs1_sd*Rs2_sd;
                }}, IntMultOp);
                0x20: sub({{
                    Rd = Rs1_sd - Rs2_sd;
                }});
            }
            0x1: decode FUNCT7 {
                0x0: sll({{
                    Rd = Rs1 << Rs2<5:0>;
                }});
                0x1: mulh({{
                    bool negate = (Rs1_sd < 0) != (Rs2_sd < 0);

                    uint64_t Rs1_lo = (uint32_t)std::abs(Rs1_sd);
                    uint64_t Rs1_hi = (uint64_t)std::abs(Rs1_sd) >> 32;
                    uint64_t Rs2_lo = (uint32_t)std::abs(Rs2_sd);
                    uint64_t Rs2_hi = (uint64_t)std::abs(Rs2_sd) >> 32;

                    uint64_t hi = Rs1_hi*Rs2_hi;
                    uint64_t mid1 = Rs1_hi*Rs2_lo;
                    uint64_t mid2 = Rs1_lo*Rs2_hi;
                    uint64_t lo = Rs2_lo*Rs1_lo;
                    uint64_t carry = ((uint64_t)(uint32_t)mid1
                            + (uint64_t)(uint32_t)mid2 + (lo >> 32)) >> 32;

                    uint64_t res = hi + (mid1 >> 32) + (mid2 >> 32) + carry;
                    Rd = negate ? ~res + (Rs1_sd*Rs2_sd == 0 ? 1 : 0) : res;
                }}, IntMultOp);
            }
            0x2: decode FUNCT7 {
                0x0: slt({{
                    Rd = (Rs1_sd < Rs2_sd) ? 1 : 0;
                }});
                0x1: mulhsu({{
                    bool negate = Rs1_sd < 0;
                    uint64_t Rs1_lo = (uint32_t)std::abs(Rs1_sd);
                    uint64_t Rs1_hi = (uint64_t)std::abs(Rs1_sd) >> 32;
                    uint64_t Rs2_lo = (uint32_t)Rs2;
                    uint64_t Rs2_hi = Rs2 >> 32;

                    uint64_t hi = Rs1_hi*Rs2_hi;
                    uint64_t mid1 = Rs1_hi*Rs2_lo;
                    uint64_t mid2 = Rs1_lo*Rs2_hi;
                    uint64_t lo = Rs1_lo*Rs2_lo;
                    uint64_t carry = ((uint64_t)(uint32_t)mid1
                            + (uint64_t)(uint32_t)mid2 + (lo >> 32)) >> 32;

                    uint64_t res = hi + (mid1 >> 32) + (mid2 >> 32) + carry;
                    Rd = negate ? ~res + (Rs1_sd*Rs2 == 0 ? 1 : 0) : res;
                }}, IntMultOp);
            }
            0x3: decode FUNCT7 {
                0x0: sltu({{
                    Rd = (Rs1 < Rs2) ? 1 : 0;
                }});
                0x1: mulhu({{
                    uint64_t Rs1_lo = (uint32_t)Rs1;
                    uint64_t Rs1_hi = Rs1 >> 32;
                    uint64_t Rs2_lo = (uint32_t)Rs2;
                    uint64_t Rs2_hi = Rs2 >> 32;

                    uint64_t hi = Rs1_hi*Rs2_hi;
                    uint64_t mid1 = Rs1_hi*Rs2_lo;
                    uint64_t mid2 = Rs1_lo*Rs2_hi;
                    uint64_t lo = Rs1_lo*Rs2_lo;
                    uint64_t carry = ((uint64_t)(uint32_t)mid1
                            + (uint64_t)(uint32_t)mid2 + (lo >> 32)) >> 32;

                    Rd = hi + (mid1 >> 32) + (mid2 >> 32) + carry;
                }}, IntMultOp);
            }
            0x4: decode FUNCT7 {
                0x0: xor({{
                    Rd = Rs1 ^ Rs2;
                }});
                0x1: div({{
                    if (Rs2_sd == 0) {
                        Rd_sd = -1;
                    } else if (Rs1_sd == std::numeric_limits<int64_t>::min()
                            && Rs2_sd == -1) {
                        Rd_sd = std::numeric_limits<int64_t>::min();
                    } else {
                        Rd_sd = Rs1_sd/Rs2_sd;
                    }
                }}, IntDivOp);
            }
            0x5: decode FUNCT7 {
                0x0: srl({{
                    Rd = Rs1 >> Rs2<5:0>;
                }});
                0x1: divu({{
                    if (Rs2 == 0) {
                        Rd = std::numeric_limits<uint64_t>::max();
                    } else {
                        Rd = Rs1/Rs2;
                    }
                }}, IntDivOp);
                0x20: sra({{
                    Rd_sd = Rs1_sd >> Rs2<5:0>;
                }});
            }
            0x6: decode FUNCT7 {
                0x0: or({{
                    Rd = Rs1 | Rs2;
                }});
                0x1: rem({{
                    if (Rs2_sd == 0) {
                        Rd = Rs1_sd;
                    } else if (Rs1_sd == std::numeric_limits<int64_t>::min()
                            && Rs2_sd == -1) {
                        Rd = 0;
                    } else {
                        Rd = Rs1_sd%Rs2_sd;
                    }
                }}, IntDivOp);
            }
            0x7: decode FUNCT7 {
                0x0: and({{
                    Rd = Rs1 & Rs2;
                }});
                0x1: remu({{
                    if (Rs2 == 0) {
                        Rd = Rs1;
                    } else {
                        Rd = Rs1%Rs2;
                    }
                }}, IntDivOp);
            }
        }
    }

    0x37: UOp::lui({{
        Rd = (uint64_t)imm;
    }});

    0x3b: decode FUNCT3 {
        format ROp {
            0x0: decode FUNCT7 {
                0x0: addw({{
                    Rd_sd = Rs1_sw + Rs2_sw;
                }});
                0x1: mulw({{
                    Rd_sd = (int32_t)(Rs1_sw*Rs2_sw);
                }}, IntMultOp);
                0x20: subw({{
                    Rd_sd = Rs1_sw - Rs2_sw;
                }});
            }
            0x1: sllw({{
                Rd_sd = Rs1_sw << Rs2<4:0>;
            }});
            0x4: divw({{
                if (Rs2_sw == 0) {
                    Rd_sd = -1;
                } else if (Rs1_sw == std::numeric_limits<int32_t>::min()
                        && Rs2_sw == -1) {
                    Rd_sd = std::numeric_limits<int32_t>::min();
                } else {
                    Rd_sd = Rs1_sw/Rs2_sw;
                }
            }}, IntDivOp);
            0x5: decode FUNCT7 {
                0x0: srlw({{
                    Rd_uw = Rs1_uw >> Rs2<4:0>;
                }});
                0x1: divuw({{
                    if (Rs2_uw == 0) {
                        Rd_sd = std::numeric_limits<IntReg>::max();
                    } else {
                        Rd_sd = (int32_t)(Rs1_uw/Rs2_uw);
                    }
                }}, IntDivOp);
                0x20: sraw({{
                    Rd_sd = Rs1_sw >> Rs2<4:0>;
                }});
            }
            0x6: remw({{
                if (Rs2_sw == 0) {
                    Rd_sd = Rs1_sw;
                } else if (Rs1_sw == std::numeric_limits<int32_t>::min()
                        && Rs2_sw == -1) {
                    Rd_sd = 0;
                } else {
                    Rd_sd = Rs1_sw%Rs2_sw;
                }
            }}, IntDivOp);
            0x7: remuw({{
                if (Rs2_uw == 0) {
                    Rd_sd = (int32_t)Rs1_uw;
                } else {
                    Rd_sd = (int32_t)(Rs1_uw%Rs2_uw);
                }
            }}, IntDivOp);
        }
    }

    0x63: decode FUNCT3 {
        format SBOp {
            0x0: beq({{
                if (Rs1 == Rs2) {
                    NPC = PC + imm;
                } else {
                    NPC = NPC;
                }
            }}, IsDirectControl, IsCondControl);
            0x1: bne({{
                if (Rs1 != Rs2) {
                    NPC = PC + imm;
                } else {
                    NPC = NPC;
                }
            }}, IsDirectControl, IsCondControl);
            0x4: blt({{
                if (Rs1_sd < Rs2_sd) {
                    NPC = PC + imm;
                } else {
                    NPC = NPC;
                }
            }}, IsDirectControl, IsCondControl);
            0x5: bge({{
                if (Rs1_sd >= Rs2_sd) {
                    NPC = PC + imm;
                } else {
                    NPC = NPC;
                }
            }}, IsDirectControl, IsCondControl);
            0x6: bltu({{
                if (Rs1 < Rs2) {
                    NPC = PC + imm;
                } else {
                    NPC = NPC;
                }
            }}, IsDirectControl, IsCondControl);
            0x7: bgeu({{
                if (Rs1 >= Rs2) {
                    NPC = PC + imm;
                } else {
                    NPC = NPC;
                }
            }}, IsDirectControl, IsCondControl);
        }
    }

    0x67: decode FUNCT3 {
        0x0: Jump::jalr({{
            Rd = NPC;
            NPC = (imm + Rs1) & (~0x1);
        }}, IsIndirectControl, IsUncondControl, IsCall);
    }

    0x6f: UJOp::jal({{
        Rd = NPC;
        NPC = PC + imm;
    }}, IsDirectControl, IsUncondControl, IsCall);

    0x73: decode FUNCT3 {
        format IOp {
            0x0: decode FUNCT12 {
                0x0: ecall({{
                    fault = std::make_shared<SyscallFault>();
                }}, IsSerializeAfter, IsNonSpeculative, IsSyscall, No_OpClass);
                0x1: ebreak({{
                    fault = std::make_shared<BreakpointFault>();
                }}, IsSerializeAfter, IsNonSpeculative, No_OpClass);
                0x100: eret({{
                    fault = std::make_shared<UnimplementedFault>("eret");
                }}, No_OpClass);
            }
            0x1: csrrw({{
                Rd = xc->readMiscReg(FUNCT12);
                xc->setMiscReg(FUNCT12, Rs1);
            }}, IsNonSpeculative, No_OpClass);
            0x2: csrrs({{
                Rd = xc->readMiscReg(FUNCT12);
                if (Rs1 != 0) {
                    xc->setMiscReg(FUNCT12, Rd | Rs1);
                }
            }}, IsNonSpeculative, No_OpClass);
            0x3: csrrc({{
                Rd = xc->readMiscReg(FUNCT12);
                if (Rs1 != 0) {
                    xc->setMiscReg(FUNCT12, Rd & ~Rs1);
                }
            }}, IsNonSpeculative, No_OpClass);
            0x5: csrrwi({{
                Rd = xc->readMiscReg(FUNCT12);
                xc->setMiscReg(FUNCT12, ZIMM);
            }}, IsNonSpeculative, No_OpClass);
            0x6: csrrsi({{
                Rd = xc->readMiscReg(FUNCT12);
                if (ZIMM != 0) {
                    xc->setMiscReg(FUNCT12, Rd | ZIMM);
                }
            }}, IsNonSpeculative, No_OpClass);
            0x7: csrrci({{
                Rd = xc->readMiscReg(FUNCT12);
                if (ZIMM != 0) {
                    xc->setMiscReg(FUNCT12, Rd & ~ZIMM);
                }
            }}, IsNonSpeculative, No_OpClass);
        }
    }
}