introduces new decoder to interp backend

gen_input/templates/interp/CORENAME.cpp.gtl

@@ -35,6 +35,7 @@ def nativeTypeSize(int size){
 }
 %>
 // clang-format off
+#include <cstdint>
 #include <iss/arch/${coreDef.name.toLowerCase()}.h>
 #include <iss/debugger/gdb_session.h>
 #include <iss/debugger/server.h>
@@ -47,6 +48,8 @@ def nativeTypeSize(int size){
 #include <exception>
 #include <vector>
 #include <sstream>
+#include <vm/instruction_decoder.h>
+
 
 #ifndef FMT_HEADER_ONLY
 #define FMT_HEADER_ONLY
@@ -152,25 +155,20 @@ private:
      * start opcode definitions
      ****************************************************************************/
     struct instruction_descriptor {
-        size_t length;
+        uint32_t length;
         uint32_t value;
         uint32_t mask;
         typename arch::traits<ARCH>::opcode_e op;
     };
-    struct decoding_tree_node{
-        std::vector<instruction_descriptor> instrs;
-        std::vector<decoding_tree_node*> children;
-        uint32_t submask = std::numeric_limits<uint32_t>::max();
-        uint32_t value;
-        decoding_tree_node(uint32_t value) : value(value){}
-    };
 
-    decoding_tree_node* root {nullptr};
     const std::array<instruction_descriptor, ${instructions.size()}> instr_descr = {{
          /* entries are: size, valid value, valid mask, function ptr */<%instructions.each{instr -> %>
         {${instr.length}, ${instr.encoding}, ${instr.mask}, arch::traits<ARCH>::opcode_e::${instr.instruction.name}},<%}%>
     }};
 
+    //needs to be declared after instr_descr
+    decoder instr_decoder;
+
     iss::status fetch_ins(virt_addr_t pc, uint8_t * data){
         if(this->core.has_mmu()) {
             auto phys_pc = this->core.virt2phys(pc);
@@ -190,58 +188,6 @@ private:
         }
         return iss::Ok;
     }
-    
-    void populate_decoding_tree(decoding_tree_node* root){
-        //create submask
-        for(auto instr: root->instrs){
-            root->submask &= instr.mask;
-        }
-        //put each instr according to submask&encoding into children
-        for(auto instr: root->instrs){
-            bool foundMatch = false;
-            for(auto child: root->children){
-                //use value as identifying trait
-                if(child->value == (instr.value&root->submask)){
-                    child->instrs.push_back(instr);
-                    foundMatch = true;
-                }
-            }
-            if(!foundMatch){
-                decoding_tree_node* child = new decoding_tree_node(instr.value&root->submask);
-                child->instrs.push_back(instr);
-                root->children.push_back(child);
-            }
-        }
-        root->instrs.clear();
-        //call populate_decoding_tree for all children
-        if(root->children.size() >1)
-            for(auto child: root->children){
-                populate_decoding_tree(child);      
-            }
-        else{
-            //sort instrs by value of the mask, this works bc we want to have the least restrictive one last
-            std::sort(root->children[0]->instrs.begin(), root->children[0]->instrs.end(), [](const instruction_descriptor& instr1, const instruction_descriptor& instr2) {
-            return instr1.mask > instr2.mask;
-            }); 
-        }
-    }
-
-    typename arch::traits<ARCH>::opcode_e  decode_instr(decoding_tree_node* node, code_word_t word){
-        if(!node->children.size()){
-            if(node->instrs.size() == 1) return node->instrs[0].op;
-            for(auto instr : node->instrs){
-                if((instr.mask&word) == instr.value) return instr.op;
-            }
-        }
-        else{
-            for(auto child : node->children){
-                if (child->value == (node->submask&word)){
-                    return decode_instr(child, word);
-                }  
-            }  
-        }
-        return arch::traits<ARCH>::opcode_e::MAX_OPCODE;
-    }
 };
 
 template <typename CODE_WORD> void debug_fn(CODE_WORD insn) {
@@ -267,13 +213,16 @@ constexpr size_t bit_count(uint32_t u) {
 
 template <typename ARCH>
 vm_impl<ARCH>::vm_impl(ARCH &core, unsigned core_id, unsigned cluster_id)
-: vm_base<ARCH>(core, core_id, cluster_id) {
+: vm_base<ARCH>(core, core_id, cluster_id)
-    root = new decoding_tree_node(std::numeric_limits<uint32_t>::max());
+, instr_decoder([this]() {
-    for(auto instr:instr_descr){
+        std::vector<generic_instruction_descriptor> g_instr_descr;
-        root->instrs.push_back(instr);
+        g_instr_descr.reserve(instr_descr.size());
+        for (uint32_t i = 0; i < instr_descr.size(); ++i) {
+            generic_instruction_descriptor new_instr_descr {instr_descr[i].value, instr_descr[i].mask, i};
+            g_instr_descr.push_back(new_instr_descr);
         }
-    populate_decoding_tree(root);
+        return std::move(g_instr_descr);
-}
+    }()) {}
 
 inline bool is_icount_limit_enabled(finish_cond_e cond){
     return (cond & finish_cond_e::ICOUNT_LIMIT) == finish_cond_e::ICOUNT_LIMIT;
@@ -310,7 +259,11 @@ typename vm_base<ARCH>::virt_addr_t vm_impl<ARCH>::execute_inst(finish_cond_e co
         } else {
             if (is_jump_to_self_enabled(cond) &&
                     (instr == 0x0000006f || (instr&0xffff)==0xa001)) throw simulation_stopped(0); // 'J 0' or 'C.J 0'
-            auto inst_id = decode_instr(root, instr);
+            uint32_t inst_index = instr_decoder.decode_instr(instr);
+            opcode_e inst_id = arch::traits<ARCH>::opcode_e::MAX_OPCODE;;
+            if(inst_index <instr_descr.size())
+                inst_id = instr_descr.at(instr_decoder.decode_instr(instr)).op;
+
             // pre execution stuff
             this->core.reg.last_branch = 0;
             if(this->sync_exec && PRE_SYNC) this->do_sync(PRE_SYNC, static_cast<unsigned>(inst_id));

src/vm/interp/vm_tgc5c.cpp

@@ -46,6 +46,7 @@
 #include <sstream>
 #include <vm/instruction_decoder.h>
 
+
 #ifndef FMT_HEADER_ONLY
 #define FMT_HEADER_ONLY
 #endif
@@ -153,6 +154,7 @@ private:
         uint32_t mask;
         typename arch::traits<ARCH>::opcode_e op;
     };
+
     const std::array<instruction_descriptor, 87> instr_descr = {{
          /* entries are: size, valid value, valid mask, function ptr */
         {32, 0b00000000000000000000000000110111, 0b00000000000000000000000001111111, arch::traits<ARCH>::opcode_e::LUI},
@@ -243,6 +245,7 @@ private:
         {16, 0b1100000000000010, 0b1110000000000011, arch::traits<ARCH>::opcode_e::C__SWSP},
         {16, 0b0000000000000000, 0b1111111111111111, arch::traits<ARCH>::opcode_e::DII},
     }};
+
     //needs to be declared after instr_descr
     decoder instr_decoder;