1 files changed, 47 insertions, 10 deletions

diff --git a/riscv/processor.h b/riscv/processor.h
index f3e5294..9b776e2 100644
--- a/riscv/processor.h
+++ b/riscv/processor.h
@@ -43,7 +43,7 @@ struct insn_desc_t
   insn_func_t logged_rv32e;
   insn_func_t logged_rv64e;
 
-  insn_func_t func(int xlen, bool rve, bool logged)
+  insn_func_t func(int xlen, bool rve, bool logged) const
   {
     if (logged)
       if (rve)
@@ -57,12 +57,7 @@ struct insn_desc_t
         return xlen == 64 ? fast_rv64i : fast_rv32i;
   }
 
-  static insn_desc_t illegal()
-  {
-    return {0, 0,
-            &illegal_instruction, &illegal_instruction, &illegal_instruction, &illegal_instruction,
-            &illegal_instruction, &illegal_instruction, &illegal_instruction, &illegal_instruction};
-  }
+  static const insn_desc_t illegal_instruction;
 };
 
 // regnum, data
@@ -141,6 +136,7 @@ struct state_t
   dcsr_csr_t_p dcsr;
   csr_t_p tselect;
   csr_t_p tdata2;
+  csr_t_p tcontrol;
   csr_t_p scontext;
   csr_t_p mcontext;
 
@@ -195,6 +191,47 @@ struct state_t
   elp_t elp;
 };
 
+class opcode_cache_entry_t {
+ public:
+  opcode_cache_entry_t()
+  {
+    reset();
+  }
+
+  void reset()
+  {
+    for (size_t i = 0; i < associativity; i++) {
+      tag[i] = 0;
+      contents[i] = &insn_desc_t::illegal_instruction;
+    }
+  }
+
+  void replace(insn_bits_t opcode, const insn_desc_t* desc)
+  {
+    for (size_t i = associativity - 1; i > 0; i--) {
+      tag[i] = tag[i-1];
+      contents[i] = contents[i-1];
+    }
+
+    tag[0] = opcode;
+    contents[0] = desc;
+  }
+
+  std::tuple<bool, const insn_desc_t*> lookup(insn_bits_t opcode)
+  {
+    for (size_t i = 0; i < associativity; i++)
+      if (tag[i] == opcode)
+        return std::tuple(true, contents[i]);
+
+    return std::tuple(false, nullptr);
+  }
+
+ private:
+  static const size_t associativity = 4;
+  insn_bits_t tag[associativity];
+  const insn_desc_t* contents[associativity];
+};
+
 // this class represents one processor in a RISC-V machine.
 class processor_t : public abstract_device_t
 {
@@ -319,7 +356,7 @@ public:
   void clear_waiting_for_interrupt() { in_wfi = false; };
   bool is_waiting_for_interrupt() { return in_wfi; };
 
-  void execute_insn_prehook(insn_t insn);
+  void check_if_lpad_required();
 
 private:
   const isa_parser_t * const isa;
@@ -350,8 +387,8 @@ private:
   std::vector<insn_desc_t> custom_instructions;
   std::unordered_map<reg_t,uint64_t> pc_histogram;
 
-  static const size_t OPCODE_CACHE_SIZE = 8191;
-  insn_desc_t opcode_cache[OPCODE_CACHE_SIZE];
+  static const size_t OPCODE_CACHE_SIZE = 4095;
+  opcode_cache_entry_t opcode_cache[OPCODE_CACHE_SIZE];
 
   void take_pending_interrupt() { take_interrupt(state.mip->read() & state.mie->read()); }
   void take_interrupt(reg_t mask); // take first enabled interrupt in mask