start implementing cached interpreter

src/backend/core/Interpreter.cpp

@@ -21,7 +21,19 @@ void Interpreter::CheckCompareInterrupt() const {
     }
 }
 
-u32 Interpreter::Step() {
+bool Interpreter::Fetch(Instruction &instr) {
+    u32 paddr = 0;
+    if (!regs.cop0.MapVAddr(Cop0::LOAD, regs.pc, paddr)) {
+        regs.cop0.HandleTLBException(regs.pc);
+        regs.cop0.FireException(Cop0::GetTLBExceptionCode(regs.cop0.tlbError, Cop0::LOAD), 0, regs.pc);
+        return false;
+    }
+
+    instr = mem.Read<u32>(paddr);
+    return true;
+}
+
+bool Interpreter::MaybeAdvance() {
     CheckCompareInterrupt();
 
     regs.prevDelaySlot = regs.delaySlot;
@@ -30,29 +42,57 @@ u32 Interpreter::Step() {
     if (check_address_error(0b11, u64(regs.pc))) [[unlikely]] {
         regs.cop0.HandleTLBException(regs.pc);
         regs.cop0.FireException(Cop0::ExceptionCode::AddressErrorLoad, 0, regs.pc);
-        return 1;
+        return false;
     }
 
-    u32 paddr = 0;
-    if (!regs.cop0.MapVAddr(Cop0::LOAD, regs.pc, paddr)) {
-        regs.cop0.HandleTLBException(regs.pc);
-        regs.cop0.FireException(Cop0::GetTLBExceptionCode(regs.cop0.tlbError, Cop0::LOAD), 0, regs.pc);
-        return 1;
-    }
-
-    const u32 instruction = mem.Read<u32>(paddr);
-
     if (ShouldServiceInterrupt()) {
         regs.cop0.FireException(Cop0::ExceptionCode::Interrupt, 0, regs.pc);
-        return 1;
+        return false;
     }
 
     regs.oldPC = regs.pc;
     regs.pc = regs.nextPC;
     regs.nextPC += 4;
 
-    Exec(instruction);
+    return true;
+}
+
+bool Interpreter::FetchThenMaybeAdvance(Instruction &instr) {
+    CheckCompareInterrupt();
+
+    regs.prevDelaySlot = regs.delaySlot;
+    regs.delaySlot = false;
+
+    if (check_address_error(0b11, u64(regs.pc))) [[unlikely]] {
+        regs.cop0.HandleTLBException(regs.pc);
+        regs.cop0.FireException(Cop0::ExceptionCode::AddressErrorLoad, 0, regs.pc);
+        return false;
+    }
+
+    if (!Fetch(instr))
+        return false;
+
+    if (ShouldServiceInterrupt()) {
+        regs.cop0.FireException(Cop0::ExceptionCode::Interrupt, 0, regs.pc);
+        return false;
+    }
+
+    regs.oldPC = regs.pc;
+    regs.pc = regs.nextPC;
+    regs.nextPC += 4;
+
+    return true;
+}
+
+u32 Interpreter::Step() {
+    Instruction instr;
+    if (!FetchThenMaybeAdvance(instr))
+        return 1;
+
+    DecodeExecute(instr);
 
     return 1;
 }
+
+u32 Interpreter::ExecuteCached() {}
 } // namespace n64

src/backend/core/Interpreter.hpp

@@ -5,23 +5,39 @@
 namespace n64 {
 struct Core;
 
+static constexpr u32 MAX_INSTRUCTION_PER_LINE = 128;
+
+struct CachedLine {
+    std::array<u32, MAX_INSTRUCTION_PER_LINE> code;
+    u32 cycles = 0;
+    u32 len = 0;
+};
+
+struct CachedBlock {
+    std::vector<CachedLine> lines;
+};
+
 struct Interpreter final {
     explicit Interpreter(Mem &, Registers &);
     ~Interpreter() = default;
     u32 Step();
+    u32 ExecuteCached();
+    bool FetchThenMaybeAdvance(Instruction &);
+    bool MaybeAdvance();
 
     void Reset() { cop2Latch = {}; }
 
   private:
+    friend struct Cop1;
     InstructionCache icache;
     DataCache dcache;
     Registers &regs;
     Mem &mem;
     u64 cop2Latch{};
-    friend struct Cop1;
 
-    void cache_type_data(u8, u64, u32, u32);
-    void cache_type_instruction(u8, u64, u32, u32);
+    bool Fetch(Instruction &);
+    void CacheTypeData(u8, u64, u32, u32);
+    void CacheTypeInstruction(u8, u64, u32, u32);
 #define check_address_error(mask, vaddr)                                                                               \
     (((!regs.cop0.is64BitAddressing) && (s32)(vaddr) != (vaddr)) || (((vaddr) & (mask)) != 0))
     [[nodiscard]] bool ShouldServiceInterrupt() const;
@@ -30,7 +46,7 @@ struct Interpreter final {
     void cop2Decode(Instruction);
     void special(Instruction);
     void regimm(Instruction);
-    void Exec(Instruction);
+    void DecodeExecute(Instruction);
     void add(Instruction);
     void addu(Instruction);
     void addi(Instruction);

src/backend/core/interpreter/decode.cpp

@@ -249,7 +249,7 @@ void Interpreter::cop2Decode(const Instruction instr) {
     }
 }
 
-void Interpreter::Exec(const Instruction instr) {
+void Interpreter::DecodeExecute(const Instruction instr) {
     // 00rr_rccc
     switch (instr.opcode()) {
     case Instruction::SPECIAL:

src/backend/core/interpreter/instructions.cpp

@@ -869,12 +869,12 @@ void Interpreter::cache(const Instruction instr) {
         panic("Unknown cache type {}", type);
 
     if (type == 0)
-        return cache_type_instruction(op, vaddr, paddr, ptag);
+        return CacheTypeInstruction(op, vaddr, paddr, ptag);
 
-    return cache_type_data(op, vaddr, paddr, ptag);
+    return CacheTypeData(op, vaddr, paddr, ptag);
 }
 
-void Interpreter::cache_type_instruction(const u8 op, const u64 vaddr, const u32 paddr, const u32 ptag) {
+void Interpreter::CacheTypeInstruction(const u8 op, const u64 vaddr, const u32 paddr, const u32 ptag) {
     switch (op) {
     case 0:
         icache.InvalidateIndex(vaddr);
@@ -899,7 +899,7 @@ void Interpreter::cache_type_instruction(const u8 op, const u64 vaddr, const u32
     }
 }
 
-void Interpreter::cache_type_data(const u8 op, const u64 vaddr, const u32 paddr, const u32 ptag) {
+void Interpreter::CacheTypeData(const u8 op, const u64 vaddr, const u32 paddr, const u32 ptag) {
     switch (op) {
     case 0:
         dcache.WriteBack<true>(vaddr, paddr);

src/utils/Instruction.hpp

@@ -4,6 +4,7 @@
 
 namespace n64 {
 struct Instruction {
+    Instruction() = default;
     Instruction(u32 v) { instr.raw = v; }
     void operator=(u32 v) { instr.raw = v; }
     operator u32() const { return instr.raw; }