introduces new decoder to interp backend

gen_input/templates/asmjit/CORENAME.cpp.gtl

@@ -96,6 +96,7 @@ protected:
     using compile_func = continuation_e (this_class::*)(virt_addr_t&, code_word_t, jit_holder&);
 
     continuation_e gen_single_inst_behavior(virt_addr_t&, unsigned int &, jit_holder&) override;
+    enum globals_e {TVAL = 0, GLOBALS_SIZE};
     void gen_block_prologue(jit_holder& jh) override;
     void gen_block_epilogue(jit_holder& jh) override;
     inline const char *name(size_t index){return traits::reg_aliases.at(index);}
@@ -261,7 +262,8 @@ template <typename ARCH>
 void vm_impl<ARCH>::gen_block_prologue(jit_holder& jh){
     jh.pc = load_reg_from_mem_Gp(jh, traits::PC);
     jh.next_pc = load_reg_from_mem_Gp(jh, traits::NEXT_PC);
-    jh.globals["tval"] = get_reg_Gp(jh.cc, 64, false);
+    jh.globals.resize(GLOBALS_SIZE);
+    jh.globals[TVAL] = get_reg_Gp(jh.cc, 64, false);
 }
 template <typename ARCH>
 void vm_impl<ARCH>::gen_block_epilogue(jit_holder& jh){
@@ -284,7 +286,7 @@ void vm_impl<ARCH>::gen_block_epilogue(jit_holder& jh){
     call_enter_trap->setArg(0, jh.arch_if_ptr);
     call_enter_trap->setArg(1, current_trap_state);
     call_enter_trap->setArg(2, current_pc);
-    call_enter_trap->setArg(3, jh.globals["tval"]);
+    call_enter_trap->setArg(3, jh.globals[TVAL]);
 
     x86_reg_t current_next_pc = get_reg_for(cc, traits::NEXT_PC);
     mov(cc, current_next_pc, get_ptr_for(jh, traits::NEXT_PC));
@@ -304,7 +306,7 @@ inline void vm_impl<ARCH>::gen_raise(jit_holder& jh, uint16_t trap_id, uint16_t
 template <typename ARCH>
 template <typename T, typename>
 void vm_impl<ARCH>::gen_set_tval(jit_holder& jh, T new_tval) {
-        mov(jh.cc, jh.globals["tval"], new_tval);
+        mov(jh.cc, jh.globals[TVAL], new_tval);
     }
 template <typename ARCH>
 void vm_impl<ARCH>::gen_set_tval(jit_holder& jh, x86_reg_t _new_tval) {
@@ -312,7 +314,7 @@ void vm_impl<ARCH>::gen_set_tval(jit_holder& jh, x86_reg_t _new_tval) {
         x86::Gp new_tval = std::get<x86::Gp>(_new_tval);
         if(new_tval.size() < 8)
             new_tval = gen_ext_Gp(jh.cc, new_tval, 64, false);
-        mov(jh.cc, jh.globals["tval"], new_tval);
+        mov(jh.cc, jh.globals[TVAL], new_tval);
     } else {
         throw std::runtime_error("Variant not supported in gen_set_tval");
     }

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) {
-    root = new decoding_tree_node(std::numeric_limits<uint32_t>::max());
-    for(auto instr:instr_descr){
-        root->instrs.push_back(instr);
-    }
-    populate_decoding_tree(root);
+: vm_base<ARCH>(core, core_id, cluster_id)
+, instr_decoder([this]() {
+        std::vector<generic_instruction_descriptor> g_instr_descr;
+        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);
         }
+        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/asmjit/vm_tgc5c.cpp

@@ -96,6 +96,7 @@ protected:
     using compile_func = continuation_e (this_class::*)(virt_addr_t&, code_word_t, jit_holder&);
 
     continuation_e gen_single_inst_behavior(virt_addr_t&, unsigned int &, jit_holder&) override;
+    enum globals_e {TVAL = 0, GLOBALS_SIZE};
     void gen_block_prologue(jit_holder& jh) override;
     void gen_block_epilogue(jit_holder& jh) override;
     inline const char *name(size_t index){return traits::reg_aliases.at(index);}
@@ -4801,7 +4802,8 @@ template <typename ARCH>
 void vm_impl<ARCH>::gen_block_prologue(jit_holder& jh){
     jh.pc = load_reg_from_mem_Gp(jh, traits::PC);
     jh.next_pc = load_reg_from_mem_Gp(jh, traits::NEXT_PC);
-    jh.globals["tval"] = get_reg_Gp(jh.cc, 64, false);
+    jh.globals.resize(GLOBALS_SIZE);
+    jh.globals[TVAL] = get_reg_Gp(jh.cc, 64, false);
 }
 template <typename ARCH>
 void vm_impl<ARCH>::gen_block_epilogue(jit_holder& jh){
@@ -4824,7 +4826,7 @@ void vm_impl<ARCH>::gen_block_epilogue(jit_holder& jh){
     call_enter_trap->setArg(0, jh.arch_if_ptr);
     call_enter_trap->setArg(1, current_trap_state);
     call_enter_trap->setArg(2, current_pc);
-    call_enter_trap->setArg(3, jh.globals["tval"]);
+    call_enter_trap->setArg(3, jh.globals[TVAL]);
 
     x86_reg_t current_next_pc = get_reg_for(cc, traits::NEXT_PC);
     mov(cc, current_next_pc, get_ptr_for(jh, traits::NEXT_PC));
@@ -4844,7 +4846,7 @@ inline void vm_impl<ARCH>::gen_raise(jit_holder& jh, uint16_t trap_id, uint16_t
 template <typename ARCH>
 template <typename T, typename>
 void vm_impl<ARCH>::gen_set_tval(jit_holder& jh, T new_tval) {
-        mov(jh.cc, jh.globals["tval"], new_tval);
+        mov(jh.cc, jh.globals[TVAL], new_tval);
     }
 template <typename ARCH>
 void vm_impl<ARCH>::gen_set_tval(jit_holder& jh, x86_reg_t _new_tval) {
@@ -4852,7 +4854,7 @@ void vm_impl<ARCH>::gen_set_tval(jit_holder& jh, x86_reg_t _new_tval) {
         x86::Gp new_tval = std::get<x86::Gp>(_new_tval);
         if(new_tval.size() < 8)
             new_tval = gen_ext_Gp(jh.cc, new_tval, 64, false);
-        mov(jh.cc, jh.globals["tval"], new_tval);
+        mov(jh.cc, jh.globals[TVAL], new_tval);
     } else {
         throw std::runtime_error("Variant not supported in gen_set_tval");
     }

src/vm/instruction_decoder.cpp

@@ -85,15 +85,13 @@ void decoder::populate_decoding_tree(decoding_tree_node& parent) {
 }
 uint32_t decoder::decode_instr(uint32_t word) { return _decode_instr(this->root, word); }
 uint32_t decoder::_decode_instr(decoding_tree_node const& node, uint32_t word) {
-    if(!node.children.size()) {
-        if(node.instrs.size() == 1)
-            return node.instrs[0].index;
-        for(auto instr : node.instrs) {
+    if(!node.instrs.empty()) {
+        for(auto& instr : node.instrs) {
             if((instr.mask & word) == instr.value)
                 return instr.index;
         }
-    } else {
-        for(auto child : node.children) {
+    } else if(!node.children.empty()) {
+        for(auto& child : node.children) {
             if(child.value == (node.submask & word)) {
                 return _decode_instr(child, word);
             }

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;