feat: optimize runtime (2x+ faster)

include/common/fzl_opcodes.h

@@ -14,6 +14,8 @@ typedef enum
   FZL_OPCODE_STORE       = 0xF10003, // Push variable to environment table
   FZL_OPCODE_LOOKUP_ENV  = 0xF10004, // Lookup name in environment table
   FZL_OPCODE_WRITE       = 0xF10005, // Wirte into variable
+  FZL_OPCODE_LOAD_LOCAL  = 0xF10006, // Load local variable
+  FZL_OPCODE_STORE_LOCAL = 0xF10007, // Store local variable
 
   FZL_OPCODE_JMP = 0xF20001, // Jump to specified IP address
   FZL_OPCODE_JZ  = 0xF20002, // Jump if top value in dstack is zero

include/compiler/utils/fzl_symtable.h

@@ -23,6 +23,9 @@ typedef struct
   fzl_node_t *node;
   size_t ip;
 
+  bool slot_set;
+  size_t slot;
+
   char *classname;
 } fzl_sym_t;
 
@@ -32,6 +35,8 @@ typedef struct
   size_t size;
   size_t remainder;
 
+  size_t free_slot;
+
   fzl_sym_t *symbols;
 } fzl_symtable_t;
 
@@ -46,6 +51,9 @@ fzl_symtable_res_t fzl_symt_put(fzl_symtable_t *symt, fzl_node_t *node,
 fzl_symtable_res_t fzl_symt_setobjclass(fzl_symtable_t *symt, char *name,
                                         char *classname);
 
+// Assign a local slot to a variable
+int fzl_symt_setslot(fzl_symtable_t *symt, char *name);
+
 // Get entry from specified symtable
 bool fzl_symt_get(fzl_symtable_t *symt, char *name, fzl_sym_t *res);
 

include/vm/internals/opcode.h

@@ -32,6 +32,8 @@ int op_rm_envtable(fzl_vm_t *vm);
 int op_store(fzl_vm_t *vm);
 int op_lookup_env(fzl_vm_t *vm);
 int op_write(fzl_vm_t *vm);
+int op_load_local(fzl_vm_t *vm);
+int op_store_local(fzl_vm_t *vm);
 
 // --- flow ---
 

src/compiler/fzl_walker.c

@@ -855,14 +855,10 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
 
       case FZL_NODETYPE_IDENTIFIER:
       {
-        size_t n = add_const(
-            walker, (fzl_const_t){.type             = FZL_CONSTTYPE_STRING,
-                                  .as.string.chars  = node->token->value,
-                                  .as.string.length = node->token->value_sz});
-
         fzl_sym_t sym;
         bool exists = false;
-        for (ssize_t i = walker->sym_top - 1; i >= 0; i--)
+        ssize_t i   = walker->sym_top - 1;
+        for (; i >= 0; i--)
           if ((exists =
                    fzl_symt_get(walker->syms[i], node->token->value, &sym)))
             break;
@@ -876,9 +872,17 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
           return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
         }
 
-        push_op(walker, FZL_OPCODE_LOADCONST);
-        push_word(walker, n);
-        push_op(walker, FZL_OPCODE_LOOKUP_ENV);
+        if (!sym.slot_set)
+        {
+          snprintf(wlast_err, sizeof(wlast_err),
+                   "internal error: local '%s' has no slot", sym.name);
+          return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+        }
+
+        size_t depth = walker->sym_top - 1 - i;
+        push_op(walker, FZL_OPCODE_LOAD_LOCAL);
+        push_word(walker, depth);
+        push_word(walker, sym.slot);
 
         current_res = (fzl_walk_res_t){
             .type = sym.type, .error = false, .classname = sym.classname};
@@ -1239,6 +1243,15 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
           return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
         }
 
+        if (fzl_symt_setslot(walker->syms[walker->sym_top - 1],
+                             node->var.identifier->token->value) < 0)
+        {
+          snprintf(wlast_err, sizeof(wlast_err),
+                   "failed to assign a local slot to '%s'",
+                   (char *)node->var.identifier->token->value);
+          return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+        }
+
         fzl_token_t *id_tok = node->var.identifier->token;
         size_t const_n      = add_const(
             walker, (fzl_const_t){.type             = FZL_CONSTTYPE_STRING,
@@ -1283,7 +1296,8 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
         {
           fzl_sym_t sym;
           bool found = false;
-          for (ssize_t i = walker->sym_top - 1; i >= 0; i--)
+          ssize_t i  = walker->sym_top - 1;
+          for (; i >= 0; i--)
             if ((found =
                      fzl_symt_get(walker->syms[i],
                                   node->binary_op.left->token->value, &sym)))
@@ -1308,14 +1322,17 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
             return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
           }
 
-          size_t const_n = add_const(
-              walker, (fzl_const_t){.type            = FZL_CONSTTYPE_STRING,
-                                    .as.string.chars = sym.name,
-                                    .as.string.length =
-                                        node->binary_op.left->token->value_sz});
-          push_op(walker, FZL_OPCODE_LOADCONST);
-          push_word(walker, const_n);
-          push_op(walker, FZL_OPCODE_WRITE);
+          if (!sym.slot_set)
+          {
+            snprintf(wlast_err, sizeof(wlast_err),
+                     "internal error: local '%s' has no slot", sym.name);
+            return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+          }
+
+          size_t depth = walker->sym_top - 1 - i;
+          push_op(walker, FZL_OPCODE_STORE_LOCAL);
+          push_word(walker, depth);
+          push_word(walker, sym.slot);
         }
         else if (node->binary_op.left->type == FZL_NODETYPE_FIELD)
         {

src/compiler/utils/fzl_symtable.c

@@ -13,6 +13,7 @@ fzl_symtable_t *fzl_mksymt()
   if (!tbl)
     return NULL;
 
+  tbl->free_slot = 0;
   tbl->remainder = 2;
   tbl->size      = 0;
   tbl->symbols   = malloc(tbl->remainder * sizeof(fzl_sym_t));
@@ -38,8 +39,13 @@ fzl_symtable_res_t fzl_symt_put(fzl_symtable_t *symt, fzl_node_t *node,
     symt->symbols = realloc(symt->symbols, symt->remainder * sizeof(fzl_sym_t));
   }
 
-  symt->symbols[symt->size++] = (fzl_sym_t){
-      .name = name, .node = node, .type = type, .ip = ip, .classname = NULL};
+  symt->symbols[symt->size++] = (fzl_sym_t){.name      = name,
+                                            .node      = node,
+                                            .type      = type,
+                                            .ip        = ip,
+                                            .classname = NULL,
+                                            .slot_set  = false,
+                                            .slot      = 0};
   return FZL_SYMTABLE_RESULT_OK;
 }
 
@@ -64,6 +70,28 @@ fzl_symtable_res_t fzl_symt_setobjclass(fzl_symtable_t *symt, char *name,
   return FZL_SYMTABLE_RESULT_ERR;
 }
 
+int fzl_symt_setslot(fzl_symtable_t *symt, char *name)
+{
+  if (!symt)
+    return -1;
+
+  for (size_t i = 0; i < symt->size; i++)
+  {
+    if (strcmp(symt->symbols[i].name, name) == 0)
+    {
+      if (symt->symbols[i].slot_set)
+        return symt->symbols[i].slot;
+
+      symt->symbols[i].slot     = symt->free_slot++;
+      symt->symbols[i].slot_set = true;
+
+      return symt->symbols[i].slot;
+    }
+  }
+
+  return -1;
+}
+
 bool fzl_symt_get(fzl_symtable_t *symt, char *name, fzl_sym_t *res)
 {
   if (!symt)

src/vm/fzl_vm_debug.c

@@ -1,4 +1,4 @@
-#include "common/fzl_opcodes.h"
+#include <common/fzl_opcodes.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <vm/fzl_vm.h>
@@ -20,6 +20,22 @@ void fzl_vm_print_ops(fzl_vm_t *vm)
 
     switch (vm->ops[i])
     {
+      case FZL_OPCODE_STORE_LOCAL:
+      {
+        size_t depth = vm->ops[++i];
+        size_t slot  = vm->ops[++i];
+        printf("STORE_LOCAL D=%zu S=%zu\n", depth, slot);
+        break;
+      }
+
+      case FZL_OPCODE_LOAD_LOCAL:
+      {
+        size_t depth = vm->ops[++i];
+        size_t slot  = vm->ops[++i];
+        printf("LOAD_LOCAL D=%zu S=%zu\n", depth, slot);
+        break;
+      }
+
       case FZL_OPCODE_BUILD_STR:
         printf("BUILD_STR %zu\n", vm->ops[++i]);
         break;

src/vm/handlers/group_ctx.c

@@ -1,4 +1,7 @@
+#include <common/fzl_value.h>
+#include <stdio.h>
 #include <vm/fzl_vm.h>
+#include <vm/fzl_vm_env.h>
 #include <vm/internals/opcode.h>
 
 // Allocate environment table and increment scope level
@@ -125,3 +128,61 @@ int op_write(fzl_vm_t *vm)
 
   return 0;
 }
+
+int op_load_local(fzl_vm_t *vm)
+{
+  size_t depth = vm->ops[++vm->ip];
+  size_t slot  = vm->ops[++vm->ip];
+
+  if (depth >= vm->etop)
+  {
+    snprintf(last_err, sizeof(last_err), "runtime error - local depth out of range");
+    print_err_data(vm);
+    return -1;
+  }
+
+  fzl_vm_env_t *env = vm->estack[vm->etop - 1 - depth];
+  if (env->size <= slot)
+  {
+    snprintf(last_err, sizeof(last_err), "runtime error - local slot out of range");
+    print_err_data(vm);
+    return -1;
+  }
+
+  vm->dstack[vm->dtop++] = env->table[slot].value;
+  return 0;
+}
+
+int op_store_local(fzl_vm_t *vm)
+{
+  if (vm->dtop < 1)
+  {
+    snprintf(last_err, sizeof(last_err),
+             "runtime error - expected value in data stack");
+    print_err_data(vm);
+    return -1;
+  }
+
+  fzl_value_t value = vm->dstack[--vm->dtop];
+
+  size_t depth = vm->ops[++vm->ip];
+  size_t slot  = vm->ops[++vm->ip];
+
+  if (depth >= vm->etop)
+  {
+    snprintf(last_err, sizeof(last_err), "runtime error - local depth out of range");
+    print_err_data(vm);
+    return -1;
+  }
+
+  fzl_vm_env_t *env = vm->estack[vm->etop - 1 - depth];
+  if (env->size <= slot)
+  {
+    snprintf(last_err, sizeof(last_err), "runtime error - local slot out of range");
+    print_err_data(vm);
+    return -1;
+  }
+
+  env->table[slot].value = value;
+  return 0;
+}

src/vm/handlers/master.c

@@ -9,10 +9,10 @@ const opcode_handler group_stack[] = {
 };
 
 // Context-relative opcodes group
-const opcode_handler group_ctx[] = {
-    [1] = op_mk_envtable, [2] = op_rm_envtable, [3] = op_store,
-    [4] = op_lookup_env,  [5] = op_write,
-};
+const opcode_handler group_ctx[] = {[1] = op_mk_envtable, [2] = op_rm_envtable,
+                                    [3] = op_store,       [4] = op_lookup_env,
+                                    [5] = op_write,       [6] = op_load_local,
+                                    [7] = op_store_local};
 
 // Flow-relative opcodes group
 const opcode_handler group_flow[] = {

tests/programs/pos_local_slots.fzs

@@ -0,0 +1,30 @@
+// Slot indices follow declaration order, not first-use order.
+uint first = 1;
+uint second = 2;
+second = second + 1;
+first = first + second;
+if (first != 4)
+  exit(1);
+
+// Shadowed locals use distinct slots in distinct environments.
+uint value = 10;
+{
+  uint value = 20;
+  value = value + 1;
+  if (value != 21)
+    exit(1);
+}
+if (value != 10)
+  exit(1);
+
+// Access an outer local from nested loop/body scopes.
+uint total = 0;
+for (uint i = 0; i < 4; i = i + 1)
+{
+  {
+    uint nested = i;
+    total = total + nested;
+  }
+}
+if (total != 6)
+  exit(1);