we can now disassemble riscv64-linux-musl-gcc hello world!

.gitignore

@@ -3,3 +3,5 @@
 /chip8
 /mos6502
 /riscv64
+/riscv64-linux-musl-cross
+/dump

riscv64.cc

@@ -46,6 +46,7 @@ enum Op {
   ADDI,
   ADDIW,
   ADDW,
+  AMOSWAP_D,
   AND,
   ANDI,
   AUIPC,
@@ -55,11 +56,45 @@ enum Op {
   BLT,
   BLTU,
   BNE,
+  C_ADD,
+  C_ADDI,
+  C_ADDIW,
+  C_ADDI16SP,
+  C_ADDI4SPN,
+  C_ADDW,
+  C_AND,
+  C_ANDI,
+  C_BEQZ,
+  C_BNEZ,
+  C_EBREAK,
+  C_FLDSP,
+  C_J,
+  C_JALR,
+  C_JR,
+  C_LD,
+  C_LDSP,
+  C_LI,
+  C_LUI,
+  C_LW,
+  C_MV,
+  C_OR,
+  C_SD,
+  C_SDSP,
+  C_SRAI,
+  C_SRLI,
+  C_SLLI,
+  C_SUB,
+  C_SUBW,
+  C_SW,
+  C_SWSP,
+  C_XOR,
   DIV,
   DIVU,
   DIVUW,
   DIVW,
   ECALL,
+  FENCE,
+  FENCE_TSO,
   JAL,
   JALR,
   LB,
@@ -67,6 +102,7 @@ enum Op {
   LD,
   LH,
   LHU,
+  LR_D,
   LUI,
   LW,
   LWU,
@@ -76,11 +112,13 @@ enum Op {
   MULW,
   OR,
   ORI,
+  PAUSE,
   REM,
   REMU,
   REMUW,
   REMW,
   SB,
+  SC_D,
   SD,
   SH,
   SLL,
@@ -103,11 +141,13 @@ enum Op {
   SUBW,
   SW,
   XOR,
-  XORI
+  XORI,
 };
 
 struct Ins {
   Op op;
+  u8 length;
+
   u8 rd;
   u8 rs1;
   union {
@@ -123,34 +163,71 @@ struct Section {
   u64 entrypoint;
 };
 
-enum class Format { NONE, R, I, I_LOAD, I_SHIFT, S, B, U, J };
+enum class Format {
+  NONE,
+  R,
+  I,
+  I_LOAD,
+  I_SHIFT,
+  S,
+  B,
+  U,
+  J,
+  CI,
+  CJ,
+  CSS,
+  CR,
+  CR1,
+  CL,
+  R_ATOMIC,
+  R_ATOMIC_LR
+};
 
 struct OpDef {
   const char *mnemonic;
   Format format;
 };
 
-static constexpr std::array<OpDef, 63> OP_TABLE = {{
+static constexpr std::array<OpDef, 101> OP_TABLE = {{
     {"???", Format::NONE},      {"add", Format::R},
     {"addi", Format::I},        {"addiw", Format::I},
-    {"addw", Format::R},        {"and", Format::R},
-    {"andi", Format::I},        {"auipc", Format::U},
-    {"beq", Format::B},         {"bge", Format::B},
-    {"bgeu", Format::B},        {"blt", Format::B},
-    {"bltu", Format::B},        {"bne", Format::B},
-    {"div", Format::R},         {"divu", Format::R},
-    {"divuw", Format::R},       {"divw", Format::R},
-    {"ecall", Format::NONE},    {"jal", Format::J},
-    {"jalr", Format::I},        {"lb", Format::I_LOAD},
-    {"lbu", Format::I_LOAD},    {"ld", Format::I_LOAD},
-    {"lh", Format::I_LOAD},     {"lhu", Format::I_LOAD},
+    {"addw", Format::R},        {"amoswap.d", Format::R_ATOMIC},
+    {"and", Format::R},         {"andi", Format::I},
+    {"auipc", Format::U},       {"beq", Format::B},
+    {"bge", Format::B},         {"bgeu", Format::B},
+    {"blt", Format::B},         {"bltu", Format::B},
+    {"bne", Format::B},         {"c.add", Format::CR},
+    {"c.addi", Format::CI},     {"c.addiw", Format::CI},
+    {"c.addi16sp", Format::CI}, {"c.addi4spn", Format::CI},
+    {"c.addw", Format::CI},     {"c.and", Format::CR},
+    {"c.andi", Format::CI},     {"c.beqz", Format::B},
+    {"c.bnez", Format::B},      {"c.ebreak", Format::CR},
+    {"c.fldsp", Format::CSS},   {"c.j", Format::CJ},
+    {"c.jalr", Format::CR1},    {"c.jr", Format::CR1},
+    {"c.ld", Format::CL},       {"c.ldsp", Format::CL},
+    {"c.li", Format::CI},       {"c.lui", Format::CI},
+    {"c.lw", Format::CL},       {"c.mv", Format::CR},
+    {"c.or", Format::CR},       {"c.sd", Format::S},
+    {"c.sdsp", Format::CSS},    {"c.slli", Format::CI},
+    {"c.srai", Format::CI},     {"c.srli", Format::CI},
+    {"c.sub", Format::CR},      {"c.subw", Format::CR},
+    {"c.sw", Format::S},        {"c.swsp", Format::CSS},
+    {"c.xor", Format::CR},      {"div", Format::R},
+    {"divu", Format::R},        {"divuw", Format::R},
+    {"divw", Format::R},        {"ecall", Format::NONE},
+    {"fence", Format::NONE},    {"fence.tso", Format::NONE},
+    {"jal", Format::J},         {"jalr", Format::I},
+    {"lb", Format::I_LOAD},     {"lbu", Format::I_LOAD},
+    {"ld", Format::I_LOAD},     {"lh", Format::I_LOAD},
+    {"lhu", Format::I_LOAD},    {"lr.d", Format::R_ATOMIC_LR},
     {"lui", Format::U},         {"lw", Format::I_LOAD},
     {"lwu", Format::I_LOAD},    {"mul", Format::R},
     {"mulh", Format::R},        {"mulhu", Format::R},
     {"mulw", Format::R},        {"or", Format::R},
-    {"ori", Format::I},         {"rem", Format::R},
-    {"remu", Format::R},        {"remuw", Format::R},
-    {"remw", Format::R},        {"sb", Format::S},
+    {"ori", Format::I},         {"pause", Format::NONE},
+    {"rem", Format::R},         {"remu", Format::R},
+    {"remuw", Format::R},       {"remw", Format::R},
+    {"sb", Format::S},          {"sc.d", Format::R_ATOMIC},
     {"sd", Format::S},          {"sh", Format::S},
     {"sll", Format::R},         {"slli", Format::I_SHIFT},
     {"slliw", Format::I_SHIFT}, {"sllw", Format::R},
@@ -198,27 +275,35 @@ public:
     }
     elf_end(elf);
 
-    u64 num_ins = m_code_section.size / 4;
+    u64 num_ins = m_code_section.size / 2;
     m_decoded.resize(num_ins);
-    for (u64 i = 0; i < num_ins; i++) {
+
+    u64 offset = 0;
+    while (offset < m_code_section.size) {
       u32 raw;
-      std::memcpy(&raw, m_memory + m_code_section.offset + i * 4, sizeof(raw));
-      m_decoded[i] = decode_raw(raw);
+      std::memcpy(&raw, m_memory + m_code_section.offset + offset, sizeof(raw));
+
+      Ins ins = decode_raw(raw);
+      ins.length = ((raw & 0b11) == 0b11) ? 4 : 2;
+      m_decoded[offset / 2] = ins;
+      disassemble_ins(ins);
+
+      offset += ins.length;
     }
   }
 
   ~RISCV64() { munmap(m_memory, MEMORY_SIZE); }
 
   void disassemble_all() {
-    for (m_pc = m_code_section.offset;
-         m_pc < m_code_section.offset + m_code_section.size; m_pc += 4) {
-      disassemble_one();
+    m_pc = m_code_section.offset;
+    while (m_pc < m_code_section.offset + m_code_section.size) {
+      Ins ins = m_decoded[(m_pc - m_code_section.offset) / 2];
+      disassemble_ins(ins);
+      m_pc += ins.length;
     }
   }
 
-  void disassemble_one() {
-    Ins ins = m_decoded[(m_pc - m_code_section.offset) / 4];
-
+  void disassemble_ins(Ins ins) {
     const OpDef &def = OP_TABLE[ins.op];
 
     switch (def.format) {
@@ -252,6 +337,32 @@ public:
     case Format::J:
       std::println("{} {}, {}", def.mnemonic, REGS[ins.rd], ins.imm);
       break;
+    case Format::CI:
+      std::println("{} {}, {}", def.mnemonic, REGS[ins.rd], ins.imm);
+      break;
+    case Format::CJ:
+      std::println("{} {}", def.mnemonic, ins.imm);
+      break;
+    case Format::CSS:
+      std::println("{} {}, {}(sp)", def.mnemonic, REGS[ins.rs2], ins.imm);
+      break;
+    case Format::CR:
+      std::println("{} {}, {}", def.mnemonic, REGS[ins.rd], REGS[ins.rs2]);
+      break;
+    case Format::CR1:
+      std::println("{} {}", def.mnemonic, REGS[ins.rs1]);
+      break;
+    case Format::CL:
+      std::println("{} {}, {}({})", def.mnemonic, REGS[ins.rd], ins.imm,
+                   REGS[ins.rs1]);
+      break;
+    case Format::R_ATOMIC_LR:
+      std::println("{} {}, ({})", def.mnemonic, REGS[ins.rd], REGS[ins.rs1]);
+      break;
+    case Format::R_ATOMIC:
+      std::println("{} {}, {}, ({})", def.mnemonic, REGS[ins.rd], REGS[ins.rs2],
+                   REGS[ins.rs1]);
+      break;
     case Format::NONE:
       std::println("{}", def.mnemonic);
       break;
@@ -300,7 +411,7 @@ public:
     while (m_pc < MEMORY_SIZE) {
       m_regs[0] = 0; // clear the zero register
 
-      Ins i = m_decoded[(m_pc - m_code_section.offset) / 4];
+      Ins i = m_decoded[(m_pc - m_code_section.offset) / 2];
 
       switch (i.op) {
       case Op::INVALID: {
@@ -640,9 +751,13 @@ public:
       case Op::XORI: {
         m_regs[i.rd] = m_regs[i.rs1] ^ i.imm;
       }; break;
+      default: {
+        std::println(stderr, "Unrecognized Op: {}", (u64)i.op);
+        exit(1);
+      }; break;
       }
 
-      m_pc += 4;
+      m_pc += i.length;
     }
   }
 
@@ -679,6 +794,284 @@ private:
   }
 
   Ins decode_raw(u32 raw) {
+    if ((raw & 0b11) != 0b11) {
+      return decode_raw_16bit((u16)raw);
+    } else {
+      return decode_raw_32bit(raw);
+    }
+  }
+
+  // https://docs.riscv.org/reference/isa/unpriv/c-st-ext.html#27-8-rvc-instruction-set-listings
+  Ins decode_raw_16bit(u16 raw) {
+    u8 opcode = raw & 0b11;
+    u32 funct3 = (raw >> 13) & 0b111;
+
+    Ins i;
+    i.op = Op::INVALID;
+
+    i.rd = (raw >> 7) & 0b11111;
+
+    switch (opcode) {
+    case 0b00: {
+      switch (funct3) {
+      case 0b000: {
+        if (raw == 0) {
+          std::println(stderr, "C: illegal instruction (all zeros)");
+          exit(1);
+        }
+
+        i.rd = ((raw >> 2) & 0b111) + 8;
+        i.rs1 = 2;
+        i.imm = (((raw >> 11) & 0b11) << 4) | (((raw >> 7) & 0b1111) << 6) |
+                (((raw >> 6) & 0b1) << 2) | (((raw >> 5) & 0b1) << 3);
+        i.op = Op::C_ADDI4SPN;
+      }; break;
+      case 0b010: {
+        i.rd = ((raw >> 2) & 0b111) + 8;
+        i.rs1 = ((raw >> 7) & 0b111) + 8;
+        i.imm = (((raw >> 10) & 0b111) << 3) | (((raw >> 6) & 0b1) << 2) |
+                (((raw >> 5) & 0b1) << 6);
+        i.op = Op::C_LW;
+      }; break;
+      case 0b011: {
+        i.rd = ((raw >> 2) & 0b111) + 8;
+        i.rs1 = ((raw >> 7) & 0b111) + 8;
+        i.imm = (((raw >> 10) & 0b111) << 3) | (((raw >> 5) & 0b11) << 6);
+        i.op = Op::C_LD;
+      }; break;
+      case 0b110: {
+        i.rs1 = ((raw >> 7) & 0b111) + 8;
+        i.rs2 = ((raw >> 2) & 0b111) + 8;
+        i.imm = (((raw >> 10) & 0b111) << 3) | (((raw >> 6) & 0b1) << 2) |
+                (((raw >> 5) & 0b1) << 6);
+        i.op = Op::C_SW;
+      }; break;
+      case 0b111: {
+        i.rs1 = ((raw >> 7) & 0b111) + 8;
+        i.rs2 = ((raw >> 2) & 0b111) + 8;
+        i.imm = (((raw >> 10) & 0b111) << 3) | (((raw >> 5) & 0b11) << 6);
+        i.op = Op::C_SD;
+      }; break;
+      default: {
+        std::println(stderr, "C: opcode=00: unrecognized funct3: {:03b}",
+                     funct3);
+        exit(1);
+      }; break;
+      }
+    }; break;
+    case 0b01: {
+      switch (funct3) {
+      case 0b000: {
+        i.imm = ((raw >> 2) & 0b11111) | (((raw >> 12) & 0b1) << 5);
+        i.imm = (i.imm << 26) >> 26;
+        i.op = Op::C_ADDI;
+      }; break;
+      case 0b001: {
+        i.rs1 = i.rd;
+        i.imm = ((raw >> 2) & 0b11111) | (((raw >> 12) & 0b1) << 5);
+        i.imm = (i.imm << 26) >> 26;
+        i.op = Op::C_ADDIW;
+      }; break;
+      case 0b010: {
+        i.imm = ((raw >> 2) & 0b11111) | (((raw >> 12) & 0b1) << 5);
+        i.imm = (i.imm << 26) >> 26;
+        i.op = Op::C_LI;
+      }; break;
+      case 0b011: {
+        if (i.rd == 2) {
+          i.imm = (((raw >> 12) & 0b1) << 9) | (((raw >> 3) & 0b11) << 7) |
+                  (((raw >> 5) & 0b1) << 6) | (((raw >> 2) & 0b1) << 5) |
+                  (((raw >> 6) & 0b1) << 4);
+          i.imm = (i.imm << 22) >> 22;
+          i.op = Op::C_ADDI16SP;
+        } else {
+          i.imm = (((raw >> 12) & 0b1) << 17) | (((raw >> 2) & 0b11111) << 12);
+          i.imm = (i.imm << 14) >> 14;
+          i.op = Op::C_LUI;
+        }
+
+      }; break;
+      case 0b100: {
+        u8 funct2 = (raw >> 10) & 0b11;
+
+        if (funct2 == 0b11) {
+
+          bool bit12 = (raw >> 12) & 0b1;
+          i.rs2 = ((raw >> 2) & 0b111) + 8;
+          u8 sub_op = (raw >> 5) & 0b11;
+
+          if (bit12 == 0) {
+            switch (sub_op) {
+            case 0b00:
+              i.op = Op::C_SUB;
+              break;
+            case 0b01:
+              i.op = Op::C_XOR;
+              break;
+            case 0b10:
+              i.op = Op::C_OR;
+              break;
+            case 0b11:
+              i.op = Op::C_AND;
+              break;
+            default:
+              std::println(
+                  stderr,
+                  "C: opcode=01: funct3=100: bit12=0: unrecognized sub_op");
+              exit(1);
+            }
+          } else {
+            switch (sub_op) {
+            case 0b00:
+              i.op = Op::C_SUBW;
+              break;
+            case 0b01:
+              i.op = Op::C_ADDW;
+              break;
+            default:
+              std::println(stderr,
+                           "C: opcode=01: funct3=100: bit12=1: unrecognized "
+                           "sub_op: {:b}",
+                           sub_op);
+              exit(1);
+            }
+          }
+        } else {
+          i.rd = ((raw >> 7) & 0b111) + 8;
+          i.rs1 = i.rd;
+          i.imm = ((raw >> 2) & 0b11111) | (((raw >> 12) & 0b1) << 5);
+
+          switch (funct2) {
+          case 0b00:
+            i.op = Op::C_SRLI;
+            break;
+          case 0b01:
+            i.op = Op::C_SRAI;
+            break;
+          case 0b10:
+            i.imm = (i.imm << 26) >> 26;
+            i.op = Op::C_ANDI;
+            break;
+          default:
+            std::println(
+                stderr,
+                "C: opcode=01: funct3=100: funct2!=11: unrecognized funct2");
+            exit(1);
+          }
+        }
+      }; break;
+      case 0b101: {
+        i.rd = 0;
+        i.imm = (((raw >> 12) & 0b1) << 11) | (((raw >> 11) & 0b1) << 4) |
+                (((raw >> 9) & 0b11) << 8) | (((raw >> 8) & 0b1) << 10) |
+                (((raw >> 7) & 0b1) << 6) | (((raw >> 6) & 0b1) << 7) |
+                (((raw >> 5) & 0b1) << 3) | (((raw >> 3) & 0b11) << 1) |
+                (((raw >> 2) & 0b1) << 5);
+        i.imm = (i.imm << 20) >> 20;
+        i.op = Op::C_J;
+      }; break;
+      case 0b110: {
+        i.rs1 = ((raw >> 7) & 0b111) + 8;
+        i.rs2 = 0;
+        i.imm = (((raw >> 12) & 0b1) << 8) | (((raw >> 10) & 0b11) << 3) |
+                (((raw >> 5) & 0b11) << 6) | (((raw >> 3) & 0b11) << 1) |
+                (((raw >> 2) & 0b1) << 5);
+        i.imm = (i.imm << 23) >> 23;
+        i.op = Op::C_BEQZ;
+      }; break;
+      case 0b111: {
+        i.rs1 = ((raw >> 7) & 0b111) + 8;
+        i.rs2 = 0;
+        i.imm = (((raw >> 12) & 0b1) << 8) | (((raw >> 10) & 0b11) << 3) |
+                (((raw >> 5) & 0b11) << 6) | (((raw >> 3) & 0b11) << 1) |
+                (((raw >> 2) & 0b1) << 5);
+        i.imm = (i.imm << 23) >> 23;
+        i.op = Op::C_BNEZ;
+      }; break;
+      default: {
+        std::println(stderr, "C: opcode=01: unrecognized funct3: {:03b}",
+                     funct3);
+        exit(1);
+      }; break;
+      }
+    }; break;
+    case 0b10: {
+      switch (funct3) {
+      case 0b000: {
+        i.imm = ((raw >> 2) & 0b11111) | (((raw >> 12) & 0b1) << 5);
+        i.op = Op::C_SLLI;
+      }; break;
+      case 0b001: {
+        i.rs1 = 2;
+        i.imm = (((raw >> 12) & 0b1) << 5) | (((raw >> 5) & 0b11) << 3) |
+                (((raw >> 2) & 0b111) << 6);
+        i.op = Op::C_FLDSP;
+      }; break;
+      case 0b011: {
+        i.rs1 = 2;
+        i.imm = (((raw >> 12) & 0b1) << 5) | (((raw >> 5) & 0b11) << 3) |
+                (((raw >> 2) & 0b111) << 6);
+        i.op = Op::C_LDSP;
+      }; break;
+      case 0b100: {
+        bool bit12 = (raw >> 12) & 0b1;
+        i.rs2 = (raw >> 2) & 0b11111;
+
+        if (bit12 == 0) {
+          if (i.rs2 == 0) {
+            i.rs1 = i.rd;
+            i.rd = 0;
+            i.imm = 0;
+            i.op = Op::C_JR;
+          } else {
+            i.rs1 = 0;
+            i.op = Op::C_MV;
+          }
+        } else {
+          if (i.rs2 == 0) {
+            if (i.rd == 0) {
+              i.op = Op::C_EBREAK;
+            } else {
+              i.rs1 = i.rd;
+              i.rd = 1;
+              i.imm = 0;
+              i.op = Op::C_JALR;
+            }
+          } else {
+            i.rs1 = i.rd;
+            i.op = Op::C_ADD;
+          }
+        }
+      }; break;
+      case 0b110: {
+        i.rs2 = (raw >> 2) & 0b11111;
+        i.rs1 = 2;
+        i.imm = (((raw >> 9) & 0b1111) << 2) | (((raw >> 7) & 0b11) << 6);
+        i.op = Op::C_SWSP;
+      }; break;
+      case 0b111: {
+        i.rs2 = (raw >> 2) & 0b11111;
+        i.imm = (((raw >> 10) & 0b111) << 3) | (((raw >> 7) & 0b111) << 6);
+        i.op = Op::C_SDSP;
+      }; break;
+      default: {
+        std::println(stderr, "C: opcode=10: unrecognized funct3: {:03b}",
+                     funct3);
+        exit(1);
+      }; break;
+      }
+    }; break;
+    default: {
+      std::println(stderr, "C: unrecognized opcode: {:02b}", opcode);
+      exit(1);
+    }; break;
+    }
+
+    return i;
+  }
+
+  // https://docs.riscv.org/reference/isa/unpriv/rv-32-64g.html
+  Ins decode_raw_32bit(u32 raw) {
     u8 opcode = raw & 0b1111111;
 
     Ins i;
@@ -925,9 +1318,36 @@ private:
         exit(1);
       }
     }; break;
-    case 0b0101111:
-      std::println(stderr, "A extension not implemented yet.");
+    case 0b0101111: {
+      u8 funct3 = (raw >> 12) & 0b111;
+      u8 funct7 = (raw >> 27) & 0b11111;
+      i.rd = (raw >> 7) & 0b11111;
+      i.rs1 = (raw >> 15) & 0b11111;
+      i.rs2 = (raw >> 20) & 0b11111;
+
+      if (funct3 == 0b011) {
+        switch (funct7) {
+        case 0b00001: {
+          i.op = Op::AMOSWAP_D;
+        }; break;
+        case 0b00010: {
+          i.op = Op::LR_D;
+        }; break;
+        case 0b00011: {
+          i.op = Op::SC_D;
+        }; break;
+        default: {
+          std::println(stderr,
+                       "0101111: funct3=011: unrecognized funct7: {:05b}",
+                       funct7);
           exit(1);
+        }; break;
+        }
+      } else {
+        std::println(stderr, "0101111: unrecognized funct3: {:03b}", funct3);
+        exit(1);
+      }
+    }; break;
     case 0b0111011: {
       u8 funct3 = (raw >> 12) & 0b111;
       u8 funct7 = (u8)((raw >> 25) & 0b1111111);
@@ -1028,7 +1448,7 @@ private:
       } else if (funct3 == 0b011) {
         i.op = Op::SD;
       } else {
-        std::println(stderr, "S-type: unrecognized funct3: {:03b}", funct3);
+        std::println(stderr, "0100011: unrecognized funct3: {:03b}", funct3);
         exit(1);
       }
     }; break;
@@ -1042,6 +1462,23 @@ private:
       i.imm = raw >> 12;
       i.op = Op::AUIPC;
     }; break;
+    case 0b0001111: {
+      u8 funct3 = (raw >> 12) & 0b111;
+      if (funct3 == 0b000) {
+        i.imm = (raw >> 20) & 0b111111111111;
+
+        if (i.imm == 0b000000010000) {
+          i.op = Op::PAUSE;
+        } else if (i.imm == 0b100000110011) {
+          i.op = Op::FENCE_TSO;
+        } else {
+          i.op = Op::FENCE;
+        }
+      } else {
+        std::println(stderr, "0001111: unrecognized funct3: {:03b}", funct3);
+        exit(1);
+      }
+    }; break;
     default:
       std::println(stderr, "Unrecognized opcode: {:07b}", opcode);
       exit(1);