diff --git a/src/ctrl/ctrl_core.c b/src/ctrl/ctrl_core.c
index 491babbc..5bc53c3d 100644
--- a/src/ctrl/ctrl_core.c
+++ b/src/ctrl/ctrl_core.c
@@ -3799,7 +3799,7 @@ internal B32
 ctrl_eval_space_read(void *u, E_Space space, void *out, Rng1U64 range)
 {
   B32 result = 0;
-  CTRL_Entity *entity = (CTRL_Entity *)space;
+  CTRL_Entity *entity = (CTRL_Entity *)space.u64[1];
   {
     switch(entity->kind)
     {
@@ -4687,7 +4687,7 @@ ctrl_thread__run(DMN_CtrlCtx *ctrl_ctx, CTRL_Msg *msg)
                   eval_modules[eval_module_idx].arch        = arch;
                   eval_modules[eval_module_idx].rdi         = di_rdi_from_key(di_scope, &dbgi_key, max_U64);
                   eval_modules[eval_module_idx].vaddr_range = mod->vaddr_range;
-                  eval_modules[eval_module_idx].space       = (U64)process;
+                  eval_modules[eval_module_idx].space.u64[1]= (U64)process;
                   if(mod == module)
                   {
                     eval_modules_primary = &eval_modules[eval_module_idx];
@@ -4719,7 +4719,7 @@ ctrl_thread__run(DMN_CtrlCtx *ctrl_ctx, CTRL_Msg *msg)
               E_ParseCtx *ctx = &parse_ctx;
               ctx->ip_vaddr          = thread_rip_vaddr;
               ctx->ip_voff           = thread_rip_voff;
-              ctx->ip_thread_space   = (E_Space)thread;
+              ctx->ip_thread_space.u64[1] = (U64)thread;
               ctx->modules           = eval_modules;
               ctx->modules_count     = eval_modules_count;
               ctx->primary_module    = eval_modules_primary;
@@ -4744,7 +4744,7 @@ ctrl_thread__run(DMN_CtrlCtx *ctrl_ctx, CTRL_Msg *msg)
               ctx->space_read    = ctrl_eval_space_read;
               ctx->primary_space = eval_modules_primary->space;
               ctx->reg_arch      = eval_modules_primary->arch;
-              ctx->reg_space     = (E_Space)thread;
+              ctx->reg_space.u64[1] = (U64)thread;
               ctx->module_base   = push_array(temp.arena, U64, 1);
               ctx->module_base[0]= module->vaddr_range.min;
               ctx->tls_base      = push_array(temp.arena, U64, 1);
diff --git a/src/df/core/df_core.c b/src/df/core/df_core.c
index afba7d71..658ae5fa 100644
--- a/src/df/core/df_core.c
+++ b/src/df/core/df_core.c
@@ -3729,13 +3729,51 @@ df_ctrl_last_stop_event(void)
 ////////////////////////////////
 //~ rjf: Evaluation Context
 
+internal DF_Entity *
+df_entity_from_eval_space(E_Space space)
+{
+  DF_Entity *entity = &df_g_nil_entity;
+  if(space.u64[0] == 0 && space.u64[1] != 0)
+  {
+    entity = (DF_Entity *)space.u64[1];
+  }
+  return entity;
+}
+
+internal E_Space
+df_eval_space_from_entity(DF_Entity *entity)
+{
+  E_Space space = {0};
+  space.u64[1] = (U64)entity;
+  return space;
+}
+
 internal B32
 df_eval_space_read(void *u, E_Space space, void *out, Rng1U64 range)
 {
   B32 result = 0;
-  DF_Entity *entity = (DF_Entity *)space;
+  DF_Entity *entity = df_entity_from_eval_space(space);
   switch(entity->kind)
   {
+    //- rjf: nil-space -> fall back to file system
+    case DF_EntityKind_Nil:
+    {
+      U128 key = space;
+      U128 hash = hs_hash_from_key(key, 0);
+      HS_Scope *scope = hs_scope_open();
+      {
+        String8 data = hs_data_from_hash(scope, hash);
+        Rng1U64 legal_range = r1u64(0, data.size);
+        Rng1U64 read_range = intersect_1u64(range, legal_range);
+        if(read_range.min < read_range.max)
+        {
+          result = 1;
+          MemoryCopy(out, data.str + read_range.min, dim_1u64(read_range));
+        }
+      }
+      hs_scope_close(scope);
+    }break;
+    
     //- rjf: default -> evaluating a debugger entity; read from entity POD evaluation
     default:
     {
@@ -3799,7 +3837,7 @@ internal B32
 df_eval_space_write(void *u, E_Space space, void *in, Rng1U64 range)
 {
   B32 result = 0;
-  DF_Entity *entity = (DF_Entity *)space;
+  DF_Entity *entity = df_entity_from_eval_space(space);
   switch(entity->kind)
   {
     //- rjf: default -> making commits to entity evaluation
@@ -4307,8 +4345,8 @@ df_string_from_simple_typed_eval(Arena *arena, DF_EvalVizStringFlags flags, U32
     {
       Temp scratch = scratch_begin(&arena, 1);
       U64 min_digits = (radix == 16) ? type_byte_size*2 : 0;
-      String8 upper64 = str8_from_u64(scratch.arena, eval.value.u128[0], radix, min_digits, digit_group_separator);
-      String8 lower64 = str8_from_u64(scratch.arena, eval.value.u128[1], radix, min_digits, digit_group_separator);
+      String8 upper64 = str8_from_u64(scratch.arena, eval.value.u128.u64[0], radix, min_digits, digit_group_separator);
+      String8 lower64 = str8_from_u64(scratch.arena, eval.value.u128.u64[1], radix, min_digits, digit_group_separator);
       result = push_str8f(arena, "%S:%S", upper64, lower64);
       scratch_end(scratch);
     }break;
@@ -5013,7 +5051,7 @@ df_expr_from_eval_viz_block_index(Arena *arena, DF_EvalVizBlock *block, U64 inde
             RDI_Scope *scope = rdi_element_from_name_idx(module->rdi, Scopes, procedure->root_scope_idx);
             U64 voff = *rdi_element_from_name_idx(module->rdi, ScopeVOffData, scope->voff_range_first);
             E_OpList oplist = {0};
-            e_oplist_push_op(arena, &oplist, RDI_EvalOp_ModuleOff, voff);
+            e_oplist_push_op(arena, &oplist, RDI_EvalOp_ModuleOff, e_value_u64(voff));
             String8 bytecode = e_bytecode_from_oplist(arena, &oplist);
             U32 type_idx = procedure->type_idx;
             RDI_TypeNode *type_node = rdi_element_from_name_idx(module->rdi, TypeNodes, type_idx);
@@ -5030,7 +5068,7 @@ df_expr_from_eval_viz_block_index(Arena *arena, DF_EvalVizBlock *block, U64 inde
             RDI_GlobalVariable *gvar = rdi_element_from_name_idx(module->rdi, GlobalVariables, element_idx);
             U64 voff = gvar->voff;
             E_OpList oplist = {0};
-            e_oplist_push_op(arena, &oplist, RDI_EvalOp_ModuleOff, voff);
+            e_oplist_push_op(arena, &oplist, RDI_EvalOp_ModuleOff, e_value_u64(voff));
             String8 bytecode = e_bytecode_from_oplist(arena, &oplist);
             U32 type_idx = gvar->type_idx;
             RDI_TypeNode *type_node = rdi_element_from_name_idx(module->rdi, TypeNodes, type_idx);
@@ -5046,7 +5084,7 @@ df_expr_from_eval_viz_block_index(Arena *arena, DF_EvalVizBlock *block, U64 inde
           {
             RDI_ThreadVariable *tvar = rdi_element_from_name_idx(module->rdi, ThreadVariables, element_idx);
             E_OpList oplist = {0};
-            e_oplist_push_op(arena, &oplist, RDI_EvalOp_TLSOff, tvar->tls_off);
+            e_oplist_push_op(arena, &oplist, RDI_EvalOp_TLSOff, e_value_u64(tvar->tls_off));
             String8 bytecode = e_bytecode_from_oplist(arena, &oplist);
             U32 type_idx = tvar->type_idx;
             RDI_TypeNode *type_node = rdi_element_from_name_idx(module->rdi, TypeNodes, type_idx);
@@ -8389,7 +8427,7 @@ df_core_begin_frame(Arena *arena, DF_CmdList *cmds, F32 dt)
       eval_modules[eval_module_idx].arch        = df_architecture_from_entity(m);
       eval_modules[eval_module_idx].rdi         = di_rdi_from_key(df_state->frame_di_scope, &dbgi_key, 0);
       eval_modules[eval_module_idx].vaddr_range = m->vaddr_rng;
-      eval_modules[eval_module_idx].space       = (U64)df_entity_ancestor_from_kind(m, DF_EntityKind_Process);
+      eval_modules[eval_module_idx].space       = df_eval_space_from_entity(df_entity_ancestor_from_kind(m, DF_EntityKind_Process));
       if(module == m)
       {
         eval_modules_primary = &eval_modules[eval_module_idx];
@@ -8435,7 +8473,7 @@ df_core_begin_frame(Arena *arena, DF_CmdList *cmds, F32 dt)
     E_ParseCtx *ctx = parse_ctx;
     ctx->ip_vaddr          = rip_vaddr;
     ctx->ip_voff           = rip_voff;
-    ctx->ip_thread_space   = (E_Space)thread;
+    ctx->ip_thread_space   = df_eval_space_from_entity(thread);
     ctx->modules           = eval_modules;
     ctx->modules_count     = eval_modules_count;
     ctx->primary_module    = eval_modules_primary;
@@ -8496,7 +8534,7 @@ df_core_begin_frame(Arena *arena, DF_CmdList *cmds, F32 dt)
     ctx->space_write       = df_eval_space_write;
     ctx->primary_space     = eval_modules_primary->space;
     ctx->reg_arch          = eval_modules_primary->arch;
-    ctx->reg_space         = (E_Space)thread;
+    ctx->reg_space         = df_eval_space_from_entity(thread);
     ctx->reg_unwind_count  = unwind_count;
     ctx->module_base       = push_array(arena, U64, 1);
     ctx->module_base[0]    = module->vaddr_rng.min;
diff --git a/src/df/core/df_core.h b/src/df/core/df_core.h
index 4d1bf51a..14bb8405 100644
--- a/src/df/core/df_core.h
+++ b/src/df/core/df_core.h
@@ -1573,6 +1573,8 @@ internal CTRL_Event df_ctrl_last_stop_event(void);
 ////////////////////////////////
 //~ rjf: Evaluation Context
 
+internal DF_Entity *df_entity_from_eval_space(E_Space space);
+internal E_Space df_eval_space_from_entity(DF_Entity *entity);
 internal B32 df_eval_space_read(void *u, E_Space space, void *out, Rng1U64 range);
 internal B32 df_eval_space_write(void *u, E_Space space, void *in, Rng1U64 range);
 internal E_Eval df_eval_from_eval_cfg_table(Arena *arena, E_Eval eval, DF_CfgTable *cfg);
diff --git a/src/df/gfx/df_gfx.c b/src/df/gfx/df_gfx.c
index 6c851765..65e3eb3f 100644
--- a/src/df/gfx/df_gfx.c
+++ b/src/df/gfx/df_gfx.c
@@ -6135,7 +6135,7 @@ df_window_update_and_render(Arena *arena, DF_Window *ws, DF_CmdList *cmds)
           DF_ExpandKey parent_key = df_expand_key_make(5381, 1);
           DF_ExpandKey key = df_expand_key_make(df_hash_from_expand_key(parent_key), 1);
           DF_EvalVizBlockList viz_blocks = df_eval_viz_block_list_from_eval_view_expr_keys(scratch.arena, eval_view, &top_level_cfg_table, expr, parent_key, key);
-          DF_Entity *entity = eval.space ? (DF_Entity *)eval.space : &df_g_nil_entity;
+          DF_Entity *entity = df_entity_from_eval_space(eval.space);
           U32 default_radix = (entity->kind == DF_EntityKind_Thread ? 16 : 10);
           DF_EvalVizWindowedRowList viz_rows = df_eval_viz_windowed_row_list_from_viz_block_list(scratch.arena, eval_view, r1s64(0, 50), &viz_blocks);
           
@@ -6241,9 +6241,8 @@ df_window_update_and_render(Arena *arena, DF_Window *ws, DF_CmdList *cmds)
               {
                 default:{}break;
                 case E_Mode_Offset:
-                if(row_eval.space >= E_Space_FIXED_COUNT)
                 {
-                  DF_Entity *space_entity = (DF_Entity *)row_eval.space;
+                  DF_Entity *space_entity = df_entity_from_eval_space(row_eval.space);
                   if(space_entity->kind == DF_EntityKind_Process)
                   {
                     U64 size = e_type_byte_size_from_key(row_eval.type_key);
diff --git a/src/df/gfx/df_views.c b/src/df/gfx/df_views.c
index e086efdb..b3b78076 100644
--- a/src/df/gfx/df_views.c
+++ b/src/df/gfx/df_views.c
@@ -1527,7 +1527,7 @@ df_watch_view_build(DF_Window *ws, DF_Panel *panel, DF_View *view, DF_WatchViewS
                 E_Expr *bp_expr = e_push_expr(scratch.arena, E_ExprKind_LeafID, 0);
                 bp_expr->type_key = bp_type;
                 bp_expr->mode = E_Mode_Offset;
-                bp_expr->space = (U64)bp;
+                bp_expr->space = df_eval_space_from_entity(bp);
                 df_append_viz_blocks_for_parent__rec(scratch.arena, eval_view, parent_key, key, title, bp_expr, &top_level_cfg_table, 0, &blocks);
               }
             }
@@ -1562,7 +1562,7 @@ df_watch_view_build(DF_Window *ws, DF_Panel *panel, DF_View *view, DF_WatchViewS
                 E_Expr *wp_expr = e_push_expr(scratch.arena, E_ExprKind_LeafID, 0);
                 wp_expr->type_key = wp_type;
                 wp_expr->mode = E_Mode_Offset;
-                wp_expr->space = (U64)wp;
+                wp_expr->space = df_eval_space_from_entity(wp);
                 df_append_viz_blocks_for_parent__rec(scratch.arena, eval_view, parent_key, key, title, wp_expr, &top_level_cfg_table, 0, &blocks);
               }
             }
@@ -1625,12 +1625,12 @@ df_watch_view_build(DF_Window *ws, DF_Panel *panel, DF_View *view, DF_WatchViewS
                 }
                 U64 row_vaddr = regs_rip_from_arch_block(arch, row->regs);
                 E_OpList ops = {0};
-                e_oplist_push_op(scratch.arena, &ops, RDI_EvalOp_ConstU64, row_vaddr);
+                e_oplist_push_op(scratch.arena, &ops, RDI_EvalOp_ConstU64, e_value_u64(row_vaddr));
                 String8 bytecode = e_bytecode_from_oplist(scratch.arena, &ops);
                 E_Expr *expr = e_push_expr(scratch.arena, E_ExprKind_LeafBytecode, 0);
                 expr->bytecode = bytecode;
                 expr->mode = E_Mode_Value;
-                expr->space = (U64)process;
+                expr->space = df_eval_space_from_entity(process);
                 expr->type_key = type_key;
                 block->expr = expr;
                 block->visual_idx_range   = r1u64(row_idx, row_idx+1);
@@ -2657,9 +2657,8 @@ df_watch_view_build(DF_Window *ws, DF_Panel *panel, DF_View *view, DF_WatchViewS
         {
           default:{}break;
           case E_Mode_Offset:
-          if(row_eval.space >= E_Space_FIXED_COUNT)
           {
-            DF_Entity *space_entity = (DF_Entity *)row_eval.space;
+            DF_Entity *space_entity = df_entity_from_eval_space(row_eval.space);
             if(space_entity->kind == DF_EntityKind_Process)
             {
               U64 size = e_type_byte_size_from_key(row_eval.type_key);
@@ -3215,7 +3214,7 @@ df_watch_view_build(DF_Window *ws, DF_Panel *panel, DF_View *view, DF_WatchViewS
                       case E_IRExtKind_Bytecode:{ext = str8_lit("[bytecode]");}break;
                       default:
                       {
-                        ext = str8_from_u64(scratch.arena, op->u64, 16, 0, 0);
+                        ext = str8_from_u64(scratch.arena, op->value.u64, 16, 0, 0);
                       }break;
                     }
                     ui_labelf("  %S%s%S", op_string, ext.size ? " " : "", ext);
diff --git a/src/eval/eval_core.h b/src/eval/eval_core.h
index 1053d737..7ab47511 100644
--- a/src/eval/eval_core.h
+++ b/src/eval/eval_core.h
@@ -36,6 +36,21 @@ struct E_MsgList
   U64 count;
 };
 
+////////////////////////////////
+//~ rjf: Register-Sized Value Type
+
+typedef union E_Value E_Value;
+union E_Value
+{
+  U64 u512[8];
+  U64 u256[4];
+  U128 u128;
+  U64 u64;
+  S64 s64;
+  F64 f64;
+  F32 f32;
+};
+
 ////////////////////////////////
 //~ rjf: Operator Info
 
@@ -60,7 +75,7 @@ struct E_OpInfo
 ////////////////////////////////
 //~ rjf: Evaluation Spaces
 
-typedef U64 E_Space;
+typedef U128 E_Space;
 //
 // NOTE(rjf): Evaluations occur within the context of a "space". Each "space"
 // refers to a different offset/address-space, but it's a bit looser of a
@@ -71,15 +86,6 @@ typedef U64 E_Space;
 // Effectively, when considering the result of an evaluation, you use the
 // value for understanding a key *into* a space, e.g. 1+2 -> 3, in a null
 // space, or &foo, in the space of PID: 1234.
-//
-// The values in the E_Space enum are reserved, but apart from those, any
-// arbitrary value can be used, and then later interpreted.
-//
-enum
-{
-  E_Space_Null,
-  E_Space_FIXED_COUNT
-};
 
 ////////////////////////////////
 //~ rjf: Evaluation Modes
@@ -114,6 +120,7 @@ struct E_Module
 
 internal U64 e_hash_from_string(U64 seed, String8 string);
 internal String8 e_raw_from_escaped_string(Arena *arena, String8 string);
+#define e_value_u64(v) (E_Value){.u64 = (v)}
 
 ////////////////////////////////
 //~ rjf: Message Functions
diff --git a/src/eval/eval_interpret.c b/src/eval/eval_interpret.c
index 4dae6a26..6089b949 100644
--- a/src/eval/eval_interpret.c
+++ b/src/eval/eval_interpret.c
@@ -24,15 +24,9 @@ e_space_read(E_Space space, void *out, Rng1U64 range)
 {
   ProfBeginFunction();
   B32 result = 0;
-  switch(space)
+  if(e_interpret_ctx->space_read != 0)
   {
-    case E_Space_FIXED_COUNT:
-    case E_Space_Null:{}break;
-    default:
-    if(e_interpret_ctx->space_read != 0)
-    {
-      result = e_interpret_ctx->space_read(e_interpret_ctx->space_rw_user_data, space, out, range);
-    }break;
+    result = e_interpret_ctx->space_read(e_interpret_ctx->space_rw_user_data, space, out, range);
   }
   ProfEnd();
   return result;
@@ -43,15 +37,9 @@ e_space_write(E_Space space, void *in, Rng1U64 range)
 {
   ProfBeginFunction();
   B32 result = 0;
-  switch(space)
+  if(e_interpret_ctx->space_write != 0)
   {
-    case E_Space_FIXED_COUNT:
-    case E_Space_Null:{}break;
-    default:
-    if(e_interpret_ctx->space_write != 0)
-    {
-      result = e_interpret_ctx->space_write(e_interpret_ctx->space_rw_user_data, space, in, range);
-    }break;
+    result = e_interpret_ctx->space_write(e_interpret_ctx->space_rw_user_data, space, in, range);
   }
   ProfEnd();
   return result;
@@ -86,7 +74,7 @@ e_interpret(String8 bytecode)
     }
     else switch(op)
     {
-      case E_IRExtKind_SetSpace:{ctrlbits = RDI_EVAL_CTRLBITS(8, 0, 0);}break;
+      case E_IRExtKind_SetSpace:{ctrlbits = RDI_EVAL_CTRLBITS(16, 0, 0);}break;
       default:
       {
         result.code = E_InterpretationCode_BadOp;
@@ -139,7 +127,7 @@ e_interpret(String8 bytecode)
     {
       case E_IRExtKind_SetSpace:
       {
-        selected_space = imm;
+        MemoryCopy(&selected_space, ptr, sizeof(E_Space));
       }break;
       
       case RDI_EvalOp_Stop:
@@ -251,6 +239,11 @@ e_interpret(String8 bytecode)
         nval.u64 = imm;
       }break;
       
+      case RDI_EvalOp_ConstU128:
+      {
+        MemoryCopy(&nval, ptr, 16);
+      }break;
+      
       case RDI_EvalOp_ConstString:
       {
         MemoryCopy(&nval, ptr, imm);
diff --git a/src/eval/eval_interpret.h b/src/eval/eval_interpret.h
index 70194c32..175a89d8 100644
--- a/src/eval/eval_interpret.h
+++ b/src/eval/eval_interpret.h
@@ -7,18 +7,6 @@
 ////////////////////////////////
 //~ rjf: Bytecode Interpretation Types
 
-typedef union E_Value E_Value;
-union E_Value
-{
-  U64 u512[8];
-  U64 u256[4];
-  U64 u128[2];
-  U64 u64;
-  S64 s64;
-  F64 f64;
-  F32 f32;
-};
-
 typedef struct E_Interpretation E_Interpretation;
 struct E_Interpretation
 {
diff --git a/src/eval/eval_ir.c b/src/eval/eval_ir.c
index 89fa9fa1..cc33b01a 100644
--- a/src/eval/eval_ir.c
+++ b/src/eval/eval_ir.c
@@ -76,13 +76,13 @@ e_select_ir_ctx(E_IRCtx *ctx)
 //- rjf: op list functions
 
 internal void
-e_oplist_push_op(Arena *arena, E_OpList *list, RDI_EvalOp opcode, U64 p)
+e_oplist_push_op(Arena *arena, E_OpList *list, RDI_EvalOp opcode, E_Value value)
 {
   U8 ctrlbits = rdi_eval_op_ctrlbits_table[opcode];
   U32 p_size = RDI_DECODEN_FROM_CTRLBITS(ctrlbits);
   E_Op *node = push_array_no_zero(arena, E_Op, 1);
   node->opcode = opcode;
-  node->u64 = p;
+  node->value = value;
   SLLQueuePush(list->first, list->last, node);
   list->op_count += 1;
   list->encoded_size += 1 + p_size;
@@ -92,10 +92,10 @@ internal void
 e_oplist_push_uconst(Arena *arena, E_OpList *list, U64 x)
 {
   if(0){}
-  else if(x <= 0xFF)       { e_oplist_push_op(arena, list, RDI_EvalOp_ConstU8,  x); }
-  else if(x <= 0xFFFF)     { e_oplist_push_op(arena, list, RDI_EvalOp_ConstU16, x); }
-  else if(x <= 0xFFFFFFFF) { e_oplist_push_op(arena, list, RDI_EvalOp_ConstU32, x); }
-  else                     { e_oplist_push_op(arena, list, RDI_EvalOp_ConstU64, x); }
+  else if(x <= 0xFF)       { e_oplist_push_op(arena, list, RDI_EvalOp_ConstU8,  e_value_u64(x)); }
+  else if(x <= 0xFFFF)     { e_oplist_push_op(arena, list, RDI_EvalOp_ConstU16, e_value_u64(x)); }
+  else if(x <= 0xFFFFFFFF) { e_oplist_push_op(arena, list, RDI_EvalOp_ConstU32, e_value_u64(x)); }
+  else                     { e_oplist_push_op(arena, list, RDI_EvalOp_ConstU64, e_value_u64(x)); }
 }
 
 internal void
@@ -103,22 +103,22 @@ e_oplist_push_sconst(Arena *arena, E_OpList *list, S64 x)
 {
   if(-0x80 <= x && x <= 0x7F)
   {
-    e_oplist_push_op(arena, list, RDI_EvalOp_ConstU8, (U64)x);
-    e_oplist_push_op(arena, list, RDI_EvalOp_TruncSigned, 8);
+    e_oplist_push_op(arena, list, RDI_EvalOp_ConstU8, e_value_u64((U64)x));
+    e_oplist_push_op(arena, list, RDI_EvalOp_TruncSigned, e_value_u64(8));
   }
   else if(-0x8000 <= x && x <= 0x7FFF)
   {
-    e_oplist_push_op(arena, list, RDI_EvalOp_ConstU16, (U64)x);
-    e_oplist_push_op(arena, list, RDI_EvalOp_TruncSigned, 16);
+    e_oplist_push_op(arena, list, RDI_EvalOp_ConstU16, e_value_u64((U64)x));
+    e_oplist_push_op(arena, list, RDI_EvalOp_TruncSigned, e_value_u64(16));
   }
   else if(-0x80000000ll <= x && x <= 0x7FFFFFFFll)
   {
-    e_oplist_push_op(arena, list, RDI_EvalOp_ConstU32, (U64)x);
-    e_oplist_push_op(arena, list, RDI_EvalOp_TruncSigned, 32);
+    e_oplist_push_op(arena, list, RDI_EvalOp_ConstU32, e_value_u64((U64)x));
+    e_oplist_push_op(arena, list, RDI_EvalOp_TruncSigned, e_value_u64(32));
   }
   else
   {
-    e_oplist_push_op(arena, list, RDI_EvalOp_ConstU64, (U64)x);
+    e_oplist_push_op(arena, list, RDI_EvalOp_ConstU64, e_value_u64((U64)x));
   }
 }
 
@@ -138,7 +138,7 @@ e_oplist_push_set_space(Arena *arena, E_OpList *list, E_Space space)
 {
   E_Op *node = push_array_no_zero(arena, E_Op, 1);
   node->opcode = E_IRExtKind_SetSpace;
-  node->u64 = space;
+  node->value.u128 = space;
   SLLQueuePush(list->first, list->last, node);
   list->op_count += 1;
   list->encoded_size += 1 + sizeof(space);
@@ -153,10 +153,10 @@ e_oplist_push_string_literal(Arena *arena, E_OpList *list, String8 string)
   E_Op *node = push_array_no_zero(arena, E_Op, 1);
   node->opcode = opcode;
   node->string = string;
-  node->u64 = Min(string.size, 64);
+  node->value.u64 = Min(string.size, 64);
   SLLQueuePush(list->first, list->last, node);
   list->op_count += 1;
-  list->encoded_size += 1 + p_size + node->u64;
+  list->encoded_size += 1 + p_size + node->value.u64;
 }
 
 internal void
@@ -206,7 +206,7 @@ e_irtree_const_u(Arena *arena, U64 v)
   
   // rjf: build
   E_IRNode *n = e_push_irnode(arena, op);
-  n->u64 = v;
+  n->value.u64 = v;
   return n;
 }
 
@@ -214,7 +214,7 @@ internal E_IRNode *
 e_irtree_unary_op(Arena *arena, RDI_EvalOp op, RDI_EvalTypeGroup group, E_IRNode *c)
 {
   E_IRNode *n = e_push_irnode(arena, op);
-  n->u64 = group;
+  n->value.u64 = group;
   e_irnode_push_child(n, c);
   return n;
 }
@@ -223,7 +223,7 @@ internal E_IRNode *
 e_irtree_binary_op(Arena *arena, RDI_EvalOp op, RDI_EvalTypeGroup group, E_IRNode *l, E_IRNode *r)
 {
   E_IRNode *n = e_push_irnode(arena, op);
-  n->u64 = group;
+  n->value.u64 = group;
   e_irnode_push_child(n, l);
   e_irnode_push_child(n, r);
   return n;
@@ -266,7 +266,7 @@ internal E_IRNode *
 e_irtree_set_space(Arena *arena, E_Space space, E_IRNode *c)
 {
   E_IRNode *root = e_push_irnode(arena, E_IRExtKind_SetSpace);
-  root->u64 = space;
+  root->value.u128 = space;
   e_irnode_push_child(root, c);
   return root;
 }
@@ -280,7 +280,7 @@ e_irtree_mem_read_type(Arena *arena, E_Space space, E_IRNode *c, E_TypeKey type_
   
   // rjf: build the read node
   E_IRNode *read_node = e_push_irnode(arena, RDI_EvalOp_MemRead);
-  read_node->u64 = byte_size;
+  read_node->value.u64 = byte_size;
   e_irnode_push_child(read_node, c);
   
   // rjf: build a signed trunc node if needed
@@ -290,7 +290,7 @@ e_irtree_mem_read_type(Arena *arena, E_Space space, E_IRNode *c, E_TypeKey type_
   if(bit_size < 64 && e_type_kind_is_signed(kind))
   {
     with_trunc = e_push_irnode(arena, RDI_EvalOp_TruncSigned);
-    with_trunc->u64 = bit_size;
+    with_trunc->value.u64 = bit_size;
     e_irnode_push_child(with_trunc, read_node);
   }
   
@@ -307,7 +307,7 @@ internal E_IRNode *
 e_irtree_convert_lo(Arena *arena, E_IRNode *c, RDI_EvalTypeGroup out, RDI_EvalTypeGroup in)
 {
   E_IRNode *n = e_push_irnode(arena, RDI_EvalOp_Convert);
-  n->u64 = in | (out << 8);
+  n->value.u64 = in | (out << 8);
   e_irnode_push_child(n, c);
   return n;
 }
@@ -327,7 +327,7 @@ e_irtree_trunc(Arena *arena, E_IRNode *c, E_TypeKey type_key)
     }
     U64 bit_size = byte_size << 3;
     result = e_push_irnode(arena, op);
-    result->u64 = bit_size;
+    result->value.u64 = bit_size;
     e_irnode_push_child(result, c);
   }
   return result;
@@ -358,22 +358,11 @@ e_irtree_convert_hi(Arena *arena, E_IRNode *c, E_TypeKey out, E_TypeKey in)
 internal E_IRNode *
 e_irtree_resolve_to_value(Arena *arena, E_Space from_space, E_Mode from_mode, E_IRNode *tree, E_TypeKey type_key)
 {
+  // TODO(rjf): @spaces double check that this path is working for register spaces
   E_IRNode *result = tree;
   if(from_mode == E_Mode_Offset)
   {
-    switch(from_space)
-    {
-#if 0
-      case E_Space_Regs:
-      {
-        result = e_irtree_unary_op(arena, RDI_EvalOp_RegReadDyn, RDI_EvalTypeGroup_U, tree);
-      }break;
-#endif
-      default:
-      {
-        result = e_irtree_mem_read_type(arena, from_space, tree, type_key);
-      }break;
-    }
+    result = e_irtree_mem_read_type(arena, from_space, tree, type_key);
   }
   return result;
 }
@@ -491,7 +480,7 @@ e_irtree_and_type_from_expr(Arena *arena, E_Expr *expr)
             
             // rjf: ops to push stack value, push offset, + read from stack value
             new_tree = e_push_irnode(arena, RDI_EvalOp_ValueRead);
-            new_tree->u64 = direct_type_size;
+            new_tree->value.u64 = direct_type_size;
             e_irnode_push_child(new_tree, offset_tree);
             e_irnode_push_child(new_tree, l.root);
           }break;
@@ -964,7 +953,12 @@ e_irtree_and_type_from_expr(Arena *arena, E_Expr *expr)
             result.root     = new_tree;
             result.type_key = final_type_key;
             result.mode     = E_Mode_Value;
-            result.space    = l_tree.space ? l_tree.space : r_tree.space;
+            result.space    = l_tree.space;
+            E_Space zero_space = {0};
+            if(MemoryMatchStruct(&result.space, &zero_space))
+            {
+              result.space = r_tree.space;
+            }
           }
         }break;
         
@@ -1008,7 +1002,12 @@ e_irtree_and_type_from_expr(Arena *arena, E_Expr *expr)
             result.root     = new_root;
             result.type_key = ptr_type;
             result.mode     = E_Mode_Value;
-            result.space    = l_tree.space ? l_tree.space : r_tree.space;
+            result.space    = l_tree.space;
+            E_Space zero_space = {0};
+            if(MemoryMatchStruct(&result.space, &zero_space))
+            {
+              result.space = r_tree.space;
+            }
           }
         }break;
         
@@ -1040,7 +1039,12 @@ e_irtree_and_type_from_expr(Arena *arena, E_Expr *expr)
           result.root     = new_tree;
           result.type_key = e_type_key_basic(E_TypeKind_U64);
           result.mode     = E_Mode_Value;
-          result.space    = l_tree.space ? l_tree.space : r_tree.space;
+          result.space    = l_tree.space;
+          E_Space zero_space = {0};
+          if(MemoryMatchStruct(&result.space, &zero_space))
+          {
+            result.space = r_tree.space;
+          }
         }break;
         
         //- rjf: pointer array comparison
@@ -1069,7 +1073,12 @@ e_irtree_and_type_from_expr(Arena *arena, E_Expr *expr)
           result.root     = e_irtree_binary_op(arena, op, RDI_EvalTypeGroup_Other, mem_root, arr_root);
           result.type_key = e_type_key_basic(E_TypeKind_Bool);
           result.mode     = E_Mode_Value;
-          result.space    = ptr_tree->space ? ptr_tree->space : arr_tree->space;
+          result.space    = ptr_tree->space;
+          E_Space zero_space = {0};
+          if(MemoryMatchStruct(&result.space, &zero_space))
+          {
+            result.space = arr_tree->space;
+          }
         }break;
       }
     }break;
@@ -1120,7 +1129,12 @@ e_irtree_and_type_from_expr(Arena *arena, E_Expr *expr)
         result.root     = new_tree;
         result.type_key = result_type;
         result.mode     = E_Mode_Value;
-        result.space    = l_expr->space ? l_expr->space : r_expr->space;
+        result.space = l_expr->space;
+        E_Space zero_space = {0};
+        if(MemoryMatchStruct(&result.space, &zero_space))
+        {
+          result.space = r_expr->space;
+        }
       }
     }break;
     
@@ -1207,13 +1221,26 @@ e_irtree_and_type_from_expr(Arena *arena, E_Expr *expr)
     case E_ExprKind_LeafID:
     {
       E_IRNode *new_tree = e_push_irnode(arena, RDI_EvalOp_ConstU64);
-      new_tree->u64   = expr->u64;
+      new_tree->value.u64 = expr->u64;
       result.root     = new_tree;
       result.type_key = expr->type_key;
       result.mode     = E_Mode_Offset;
       result.space    = expr->space;
     }break;
     
+    //- rjf: leaf file paths
+    case E_ExprKind_LeafFilePath:
+    {
+      U128 key = fs_key_from_path(expr->string);
+      U64 size = fs_size_from_path(expr->string);
+      E_IRNode *base_offset = e_irtree_const_u(arena, 0);
+      E_IRNode *set_space = e_irtree_set_space(arena, key, base_offset);
+      result.root     = set_space;
+      result.type_key = e_type_key_cons_array(e_type_key_basic(E_TypeKind_U8), size);
+      result.mode     = E_Mode_Offset;
+      result.space    = key;
+    }break;
+    
     //- rjf: types
     case E_ExprKind_TypeIdent:
     {
@@ -1269,7 +1296,7 @@ e_append_oplist_from_irtree(Arena *arena, E_IRNode *root, E_OpList *out)
     
     case E_IRExtKind_SetSpace:
     {
-      e_oplist_push_set_space(arena, out, root->u64);
+      e_oplist_push_set_space(arena, out, root->value.u128);
       for(E_IRNode *child = root->first;
           child != &e_irnode_nil;
           child = child->next)
@@ -1292,11 +1319,11 @@ e_append_oplist_from_irtree(Arena *arena, E_IRNode *root, E_OpList *out)
       //  3. <ptr_left>
       
       // rjf: modify prt_right in place to create step 2
-      e_oplist_push_op(arena, &prt_right, RDI_EvalOp_Skip, prt_left.encoded_size);
+      e_oplist_push_op(arena, &prt_right, RDI_EvalOp_Skip, e_value_u64(prt_left.encoded_size));
       
       // rjf: merge 1 into out
       e_oplist_concat_in_place(out, &prt_cond);
-      e_oplist_push_op(arena, out, RDI_EvalOp_Cond, prt_right.encoded_size);
+      e_oplist_push_op(arena, out, RDI_EvalOp_Cond, e_value_u64(prt_right.encoded_size));
       
       // rjf: merge 2 into out
       e_oplist_concat_in_place(out, &prt_right);
@@ -1330,7 +1357,7 @@ e_append_oplist_from_irtree(Arena *arena, E_IRNode *root, E_OpList *out)
         }
         
         // rjf: emit op to compute this node
-        e_oplist_push_op(arena, out, (RDI_EvalOp)root->op, root->u64);
+        e_oplist_push_op(arena, out, (RDI_EvalOp)root->op, root->value);
       }
     }break;
   }
@@ -1371,7 +1398,7 @@ e_bytecode_from_oplist(Arena *arena, E_OpList *oplist)
         
         // rjf: fill bytecode
         ptr[0] = opcode;
-        MemoryCopy(ptr + 1, &op->u64, extra_byte_count);
+        MemoryCopy(ptr + 1, &op->value.u64, extra_byte_count);
         
         // rjf: advance
         ptr = next_ptr;
@@ -1380,13 +1407,13 @@ e_bytecode_from_oplist(Arena *arena, E_OpList *oplist)
       case RDI_EvalOp_ConstString:
       {
         // rjf: compute bytecode advance
-        U8 *next_ptr = ptr + 2 + op->u64;
+        U8 *next_ptr = ptr + 2 + op->value.u64;
         Assert(next_ptr <= opl);
         
         // rjf: fill
         ptr[0] = opcode;
-        ptr[1] = (U8)op->u64;
-        MemoryCopy(ptr+2, op->string.str, op->u64);
+        ptr[1] = (U8)op->value.u64;
+        MemoryCopy(ptr+2, op->string.str, op->value.u64);
         
         // rjf: advance
         ptr = next_ptr;
@@ -1415,7 +1442,7 @@ e_bytecode_from_oplist(Arena *arena, E_OpList *oplist)
         
         // rjf: fill bytecode
         ptr[0] = opcode;
-        MemoryCopy(ptr + 1, &op->u64, extra_byte_count);
+        MemoryCopy(ptr + 1, &op->value.u64, extra_byte_count);
         
         // rjf: advance
         ptr = next_ptr;
diff --git a/src/eval/eval_ir.h b/src/eval/eval_ir.h
index 67c575c1..d5485c1f 100644
--- a/src/eval/eval_ir.h
+++ b/src/eval/eval_ir.h
@@ -19,7 +19,7 @@ struct E_Op
 {
   E_Op *next;
   RDI_EvalOp opcode;
-  U64 u64;
+  E_Value value;
   String8 string;
 };
 
@@ -43,7 +43,7 @@ struct E_IRNode
   E_IRNode *next;
   RDI_EvalOp op;
   String8 string;
-  U64 u64;
+  E_Value value;
 };
 
 typedef struct E_IRTreeAndType E_IRTreeAndType;
@@ -87,7 +87,7 @@ internal void e_select_ir_ctx(E_IRCtx *ctx);
 //~ rjf: IR-ization Functions
 
 //- rjf: op list functions
-internal void e_oplist_push_op(Arena *arena, E_OpList *list, RDI_EvalOp opcode, U64 p);
+internal void e_oplist_push_op(Arena *arena, E_OpList *list, RDI_EvalOp opcode, E_Value value);
 internal void e_oplist_push_uconst(Arena *arena, E_OpList *list, U64 x);
 internal void e_oplist_push_sconst(Arena *arena, E_OpList *list, S64 x);
 internal void e_oplist_push_bytecode(Arena *arena, E_OpList *list, String8 bytecode);
diff --git a/src/eval/eval_parse.c b/src/eval/eval_parse.c
index b141273f..b1691339 100644
--- a/src/eval/eval_parse.c
+++ b/src/eval/eval_parse.c
@@ -1257,7 +1257,7 @@ e_parse_expr_from_text_tokens__prec(Arena *arena, String8 text, E_TokenArray *to
           REGS_AliasCode          alias_code = 0;
           E_TypeKey               type_key = zero_struct;
           String8                 local_lookup_string = token_string;
-          E_Space                 space = E_Space_Null;
+          E_Space                 space = {0};
           Architecture            arch = Architecture_Null;
           
           //- rjf: identifiers surrounded by ``s should have those `s stripped
@@ -1430,7 +1430,7 @@ e_parse_expr_from_text_tokens__prec(Arena *arena, String8 text, E_TokenArray *to
                 U32 match_idx = matches[matches_count-1];
                 RDI_GlobalVariable *global_var = rdi_element_from_name_idx(rdi, GlobalVariables, match_idx);
                 E_OpList oplist = {0};
-                e_oplist_push_op(arena, &oplist, RDI_EvalOp_ModuleOff, global_var->voff);
+                e_oplist_push_op(arena, &oplist, RDI_EvalOp_ModuleOff, e_value_u64(global_var->voff));
                 loc_kind = RDI_LocationKind_AddrBytecodeStream;
                 loc_bytecode = e_bytecode_from_oplist(arena, &oplist);
                 U32 type_idx = global_var->type_idx;
@@ -1470,7 +1470,7 @@ e_parse_expr_from_text_tokens__prec(Arena *arena, String8 text, E_TokenArray *to
                 U32 match_idx = matches[0];
                 RDI_ThreadVariable *thread_var = rdi_element_from_name_idx(rdi, ThreadVariables, match_idx);
                 E_OpList oplist = {0};
-                e_oplist_push_op(arena, &oplist, RDI_EvalOp_TLSOff, thread_var->tls_off);
+                e_oplist_push_op(arena, &oplist, RDI_EvalOp_TLSOff, e_value_u64(thread_var->tls_off));
                 loc_kind = RDI_LocationKind_AddrBytecodeStream;
                 loc_bytecode = e_bytecode_from_oplist(arena, &oplist);
                 U32 type_idx = thread_var->type_idx;
@@ -1512,7 +1512,7 @@ e_parse_expr_from_text_tokens__prec(Arena *arena, String8 text, E_TokenArray *to
                 RDI_Scope *scope = rdi_element_from_name_idx(rdi, Scopes, procedure->root_scope_idx);
                 U64 voff = *rdi_element_from_name_idx(rdi, ScopeVOffData, scope->voff_range_first);
                 E_OpList oplist = {0};
-                e_oplist_push_op(arena, &oplist, RDI_EvalOp_ModuleOff, voff);
+                e_oplist_push_op(arena, &oplist, RDI_EvalOp_ModuleOff, e_value_u64(voff));
                 loc_kind = RDI_LocationKind_ValBytecodeStream;
                 loc_bytecode = e_bytecode_from_oplist(arena, &oplist);
                 U32 type_idx = procedure->type_idx;
@@ -1534,7 +1534,7 @@ e_parse_expr_from_text_tokens__prec(Arena *arena, String8 text, E_TokenArray *to
             {
               mapped_identifier = 1;
               identifier_looks_like_type_expr = 1;
-              space = E_Space_Null;
+              MemoryZeroStruct(&space);
               arch = e_parse_ctx->primary_module->arch;
             }
           }
@@ -1611,9 +1611,9 @@ e_parse_expr_from_text_tokens__prec(Arena *arena, String8 text, E_TokenArray *to
                 E_OpList oplist = {0};
                 U64 byte_size = bit_size_from_arch(arch)/8;
                 U64 regread_param = RDI_EncodeRegReadParam(loc_reg_u16.reg_code, byte_size, 0);
-                e_oplist_push_op(arena, &oplist, RDI_EvalOp_RegRead, regread_param);
-                e_oplist_push_op(arena, &oplist, RDI_EvalOp_ConstU16, loc_reg_u16.offset);
-                e_oplist_push_op(arena, &oplist, RDI_EvalOp_Add, 0);
+                e_oplist_push_op(arena, &oplist, RDI_EvalOp_RegRead, e_value_u64(regread_param));
+                e_oplist_push_op(arena, &oplist, RDI_EvalOp_ConstU16, e_value_u64(loc_reg_u16.offset));
+                e_oplist_push_op(arena, &oplist, RDI_EvalOp_Add, e_value_u64(0));
                 atom = e_push_expr(arena, E_ExprKind_LeafBytecode, token_string.str);
                 atom->mode     = E_Mode_Offset;
                 atom->space    = space;
@@ -1626,10 +1626,10 @@ e_parse_expr_from_text_tokens__prec(Arena *arena, String8 text, E_TokenArray *to
                 E_OpList oplist = {0};
                 U64 byte_size = bit_size_from_arch(arch)/8;
                 U64 regread_param = RDI_EncodeRegReadParam(loc_reg_u16.reg_code, byte_size, 0);
-                e_oplist_push_op(arena, &oplist, RDI_EvalOp_RegRead, regread_param);
-                e_oplist_push_op(arena, &oplist, RDI_EvalOp_ConstU16, loc_reg_u16.offset);
-                e_oplist_push_op(arena, &oplist, RDI_EvalOp_Add, 0);
-                e_oplist_push_op(arena, &oplist, RDI_EvalOp_MemRead, bit_size_from_arch(arch)/8);
+                e_oplist_push_op(arena, &oplist, RDI_EvalOp_RegRead, e_value_u64(regread_param));
+                e_oplist_push_op(arena, &oplist, RDI_EvalOp_ConstU16, e_value_u64(loc_reg_u16.offset));
+                e_oplist_push_op(arena, &oplist, RDI_EvalOp_Add, e_value_u64(0));
+                e_oplist_push_op(arena, &oplist, RDI_EvalOp_MemRead, e_value_u64(bit_size_from_arch(arch)/8));
                 atom = e_push_expr(arena, E_ExprKind_LeafBytecode, token_string.str);
                 atom->mode     = E_Mode_Offset;
                 atom->space    = space;
@@ -1645,7 +1645,7 @@ e_parse_expr_from_text_tokens__prec(Arena *arena, String8 text, E_TokenArray *to
                 U64 byte_size = (U64)reg_rng.byte_size;
                 U64 byte_pos = 0;
                 U64 regread_param = RDI_EncodeRegReadParam(loc_reg.reg_code, byte_size, byte_pos);
-                e_oplist_push_op(arena, &oplist, RDI_EvalOp_RegRead, regread_param);
+                e_oplist_push_op(arena, &oplist, RDI_EvalOp_RegRead, e_value_u64(regread_param));
                 atom = e_push_expr(arena, E_ExprKind_LeafBytecode, token_string.str);
                 atom->mode     = E_Mode_Value;
                 atom->space    = space;
diff --git a/src/file_stream/file_stream.c b/src/file_stream/file_stream.c
index 69913f9f..f4d80975 100644
--- a/src/file_stream/file_stream.c
+++ b/src/file_stream/file_stream.c
@@ -138,6 +138,32 @@ fs_timestamp_from_path(String8 path)
   return result;
 }
 
+internal U64
+fs_size_from_path(String8 path)
+{
+  Temp scratch = scratch_begin(0, 0);
+  U64 result = 0;
+  path = path_normalized_from_string(scratch.arena, path);
+  U128 path_key = hs_hash_from_data(path);
+  U64 slot_idx = path_key.u64[0]%fs_shared->slots_count;
+  U64 stripe_idx = slot_idx%fs_shared->stripes_count;
+  FS_Slot *slot = &fs_shared->slots[slot_idx];
+  FS_Stripe *stripe = &fs_shared->stripes[stripe_idx];
+  OS_MutexScopeR(stripe->rw_mutex)
+  {
+    for(FS_Node *n = slot->first; n != 0; n = n->next)
+    {
+      if(str8_match(path, n->path, 0))
+      {
+        result = n->size;
+        break;
+      }
+    }
+  }
+  scratch_end(scratch);
+  return result;
+}
+
 ////////////////////////////////
 //~ rjf: Streamer Threads
 
@@ -263,6 +289,7 @@ fs_streamer_thread__entry_point(void *p)
         if(post_props.modified == pre_props.modified)
         {
           node->timestamp = post_props.modified;
+          node->size = post_props.size;
         }
         ins_atomic_u32_eval_assign(&node->is_working, 0);
       }
diff --git a/src/file_stream/file_stream.h b/src/file_stream/file_stream.h
index 59762876..86c6d47c 100644
--- a/src/file_stream/file_stream.h
+++ b/src/file_stream/file_stream.h
@@ -13,6 +13,7 @@ struct FS_Node
   FS_Node *next;
   String8 path;
   U64 timestamp;
+  U64 size;
   B32 is_working;
 };
 
@@ -83,6 +84,7 @@ internal U64 fs_change_gen(void);
 internal U128 fs_hash_from_path(String8 path, U64 endt_us);
 internal U128 fs_key_from_path(String8 path);
 internal U64 fs_timestamp_from_path(String8 path);
+internal U64 fs_size_from_path(String8 path);
 
 ////////////////////////////////
 //~ rjf: Streamer Threads
diff --git a/src/lib_rdi_format/rdi_format.c b/src/lib_rdi_format/rdi_format.c
index 34733dee..430d704d 100644
--- a/src/lib_rdi_format/rdi_format.c
+++ b/src/lib_rdi_format/rdi_format.c
@@ -92,7 +92,7 @@ RDI_U8 rdi_section_is_required_table[37] =
 0,
 };
 
-RDI_U8 rdi_eval_op_ctrlbits_table[47] =
+RDI_U8 rdi_eval_op_ctrlbits_table[48] =
 {
 RDI_EVAL_CTRLBITS(0, 0, 0),
 RDI_EVAL_CTRLBITS(0, 0, 0),
@@ -110,6 +110,7 @@ RDI_EVAL_CTRLBITS(1, 0, 1),
 RDI_EVAL_CTRLBITS(2, 0, 1),
 RDI_EVAL_CTRLBITS(4, 0, 1),
 RDI_EVAL_CTRLBITS(8, 0, 1),
+RDI_EVAL_CTRLBITS(16, 0, 1),
 RDI_EVAL_CTRLBITS(1, 0, 1),
 RDI_EVAL_CTRLBITS(1, 1, 1),
 RDI_EVAL_CTRLBITS(1, 1, 1),
diff --git a/src/lib_rdi_format/rdi_format.h b/src/lib_rdi_format/rdi_format.h
index 0ece5986..18d985e2 100644
--- a/src/lib_rdi_format/rdi_format.h
+++ b/src/lib_rdi_format/rdi_format.h
@@ -52,7 +52,7 @@ typedef int64_t  RDI_S64;
 
 // \"raddbg\0\0\"
 #define RDI_MAGIC_CONSTANT   0x0000676264646172
-#define RDI_ENCODING_VERSION 9
+#define RDI_ENCODING_VERSION 10
 
 ////////////////////////////////////////////////////////////////
 //~ Format Types & Functions
@@ -453,37 +453,38 @@ RDI_EvalOp_ConstU8              = 12,
 RDI_EvalOp_ConstU16             = 13,
 RDI_EvalOp_ConstU32             = 14,
 RDI_EvalOp_ConstU64             = 15,
-RDI_EvalOp_ConstString          = 16,
-RDI_EvalOp_Abs                  = 17,
-RDI_EvalOp_Neg                  = 18,
-RDI_EvalOp_Add                  = 19,
-RDI_EvalOp_Sub                  = 20,
-RDI_EvalOp_Mul                  = 21,
-RDI_EvalOp_Div                  = 22,
-RDI_EvalOp_Mod                  = 23,
-RDI_EvalOp_LShift               = 24,
-RDI_EvalOp_RShift               = 25,
-RDI_EvalOp_BitAnd               = 26,
-RDI_EvalOp_BitOr                = 27,
-RDI_EvalOp_BitXor               = 28,
-RDI_EvalOp_BitNot               = 29,
-RDI_EvalOp_LogAnd               = 30,
-RDI_EvalOp_LogOr                = 31,
-RDI_EvalOp_LogNot               = 32,
-RDI_EvalOp_EqEq                 = 33,
-RDI_EvalOp_NtEq                 = 34,
-RDI_EvalOp_LsEq                 = 35,
-RDI_EvalOp_GrEq                 = 36,
-RDI_EvalOp_Less                 = 37,
-RDI_EvalOp_Grtr                 = 38,
-RDI_EvalOp_Trunc                = 39,
-RDI_EvalOp_TruncSigned          = 40,
-RDI_EvalOp_Convert              = 41,
-RDI_EvalOp_Pick                 = 42,
-RDI_EvalOp_Pop                  = 43,
-RDI_EvalOp_Insert               = 44,
-RDI_EvalOp_ValueRead            = 45,
-RDI_EvalOp_COUNT                = 46,
+RDI_EvalOp_ConstU128            = 16,
+RDI_EvalOp_ConstString          = 17,
+RDI_EvalOp_Abs                  = 18,
+RDI_EvalOp_Neg                  = 19,
+RDI_EvalOp_Add                  = 20,
+RDI_EvalOp_Sub                  = 21,
+RDI_EvalOp_Mul                  = 22,
+RDI_EvalOp_Div                  = 23,
+RDI_EvalOp_Mod                  = 24,
+RDI_EvalOp_LShift               = 25,
+RDI_EvalOp_RShift               = 26,
+RDI_EvalOp_BitAnd               = 27,
+RDI_EvalOp_BitOr                = 28,
+RDI_EvalOp_BitXor               = 29,
+RDI_EvalOp_BitNot               = 30,
+RDI_EvalOp_LogAnd               = 31,
+RDI_EvalOp_LogOr                = 32,
+RDI_EvalOp_LogNot               = 33,
+RDI_EvalOp_EqEq                 = 34,
+RDI_EvalOp_NtEq                 = 35,
+RDI_EvalOp_LsEq                 = 36,
+RDI_EvalOp_GrEq                 = 37,
+RDI_EvalOp_Less                 = 38,
+RDI_EvalOp_Grtr                 = 39,
+RDI_EvalOp_Trunc                = 40,
+RDI_EvalOp_TruncSigned          = 41,
+RDI_EvalOp_Convert              = 42,
+RDI_EvalOp_Pick                 = 43,
+RDI_EvalOp_Pop                  = 44,
+RDI_EvalOp_Insert               = 45,
+RDI_EvalOp_ValueRead            = 46,
+RDI_EvalOp_COUNT                = 47,
 } RDI_EvalOpEnum;
 
 typedef RDI_U8 RDI_EvalTypeGroup;
@@ -858,6 +859,7 @@ X(ConstU8)\
 X(ConstU16)\
 X(ConstU32)\
 X(ConstU64)\
+X(ConstU128)\
 X(ConstString)\
 X(Abs)\
 X(Neg)\
@@ -993,10 +995,10 @@ typedef RDI_U32_Table RDI_U32_NameMapBuckets;
 typedef RDI_U32_Table RDI_U32_NameMapNodes;
 #endif
 
-#define RDI_EVAL_CTRLBITS(decodeN,popN,pushN) ((decodeN) | ((popN) << 4) | ((pushN) << 6))
-#define RDI_DECODEN_FROM_CTRLBITS(ctrlbits)   ((ctrlbits) & 0xf)
-#define RDI_POPN_FROM_CTRLBITS(ctrlbits)      (((ctrlbits) >> 4) & 0x3)
-#define RDI_PUSHN_FROM_CTRLBITS(ctrlbits)     (((ctrlbits) >> 6) & 0x3)
+#define RDI_EVAL_CTRLBITS(decodeN,popN,pushN) ((decodeN) | ((popN) << 5) | ((pushN) << 7))
+#define RDI_DECODEN_FROM_CTRLBITS(ctrlbits)   ((ctrlbits) & 0x1f)
+#define RDI_POPN_FROM_CTRLBITS(ctrlbits)      (((ctrlbits) >> 5) & 0x3)
+#define RDI_PUSHN_FROM_CTRLBITS(ctrlbits)     (((ctrlbits) >> 7) & 0x1)
 #define RDI_EncodeRegReadParam(reg,bytesize,bytepos) ((reg)|((bytesize)<<8)|((bytepos)<<16))
 
 typedef struct RDI_Header RDI_Header;
@@ -1357,6 +1359,6 @@ RDI_PROC RDI_U8 *rdi_explanation_string_from_eval_conversion_kind(RDI_EvalConver
 
 extern RDI_U16 rdi_section_element_size_table[37];
 extern RDI_U8 rdi_section_is_required_table[37];
-extern RDI_U8 rdi_eval_op_ctrlbits_table[47];
+extern RDI_U8 rdi_eval_op_ctrlbits_table[48];
 
 #endif // RDI_FORMAT_H
diff --git a/src/rdi_format/rdi_format.mdesk b/src/rdi_format/rdi_format.mdesk
index eeafb075..296fe70a 100644
--- a/src/rdi_format/rdi_format.mdesk
+++ b/src/rdi_format/rdi_format.mdesk
@@ -62,7 +62,7 @@
   "";
   "// \"raddbg\0\0\"";
   "#define RDI_MAGIC_CONSTANT   0x0000676264646172";
-  "#define RDI_ENCODING_VERSION 9";
+  "#define RDI_ENCODING_VERSION 10";
   "";
   "////////////////////////////////////////////////////////////////";
   "//~ Format Types & Functions";
@@ -1246,37 +1246,38 @@ RDI_EvalOpTable:
   {ConstU16    13      2 0 1}
   {ConstU32    14      4 0 1}
   {ConstU64    15      8 0 1}
-  {ConstString 16      1 0 1}
-  {Abs         17      1 1 1}
-  {Neg         18      1 1 1}
-  {Add         19      1 2 1}
-  {Sub         20      1 2 1}
-  {Mul         21      1 2 1}
-  {Div         22      1 2 1}
-  {Mod         23      1 2 1}
-  {LShift      24      1 2 1}
-  {RShift      25      1 2 1}
-  {BitAnd      26      1 2 1}
-  {BitOr       27      1 2 1}
-  {BitXor      28      1 2 1}
-  {BitNot      29      1 1 1}
-  {LogAnd      30      1 2 1}
-  {LogOr       31      1 2 1}
-  {LogNot      32      1 1 1}
-  {EqEq        33      1 2 1}
-  {NtEq        34      1 2 1}
-  {LsEq        35      1 2 1}
-  {GrEq        36      1 2 1}
-  {Less        37      1 2 1}
-  {Grtr        38      1 2 1}
-  {Trunc       39      1 1 1}
-  {TruncSigned 40      1 1 1}
-  {Convert     41      2 1 1}
-  {Pick        42      1 0 1}
-  {Pop         43      0 1 0}
-  {Insert      44      1 0 0}
-  {ValueRead   45      1 2 1}
-  {COUNT       46      0 0 0}
+  {ConstU128   16     16 0 1}
+  {ConstString 17      1 0 1}
+  {Abs         18      1 1 1}
+  {Neg         19      1 1 1}
+  {Add         20      1 2 1}
+  {Sub         21      1 2 1}
+  {Mul         22      1 2 1}
+  {Div         23      1 2 1}
+  {Mod         24      1 2 1}
+  {LShift      25      1 2 1}
+  {RShift      26      1 2 1}
+  {BitAnd      27      1 2 1}
+  {BitOr       28      1 2 1}
+  {BitXor      29      1 2 1}
+  {BitNot      30      1 1 1}
+  {LogAnd      31      1 2 1}
+  {LogOr       32      1 2 1}
+  {LogNot      33      1 1 1}
+  {EqEq        34      1 2 1}
+  {NtEq        35      1 2 1}
+  {LsEq        36      1 2 1}
+  {GrEq        37      1 2 1}
+  {Less        38      1 2 1}
+  {Grtr        39      1 2 1}
+  {Trunc       40      1 1 1}
+  {TruncSigned 41      1 1 1}
+  {Convert     42      2 1 1}
+  {Pick        43      1 0 1}
+  {Pop         44      0 1 0}
+  {Insert      45      1 0 0}
+  {ValueRead   46      1 2 1}
+  {COUNT       47      0 0 0}
 }
 
 // NOTE(rjf): "ck" -> "conversion kind, when converted to type group", used in square matrix form
@@ -1335,10 +1336,10 @@ RDI_EvalConversionKindTable:
 
 @gen(enums)
 ```
-#define RDI_EVAL_CTRLBITS(decodeN,popN,pushN) ((decodeN) | ((popN) << 4) | ((pushN) << 6))
-#define RDI_DECODEN_FROM_CTRLBITS(ctrlbits)   ((ctrlbits) & 0xf)
-#define RDI_POPN_FROM_CTRLBITS(ctrlbits)      (((ctrlbits) >> 4) & 0x3)
-#define RDI_PUSHN_FROM_CTRLBITS(ctrlbits)     (((ctrlbits) >> 6) & 0x3)
+#define RDI_EVAL_CTRLBITS(decodeN,popN,pushN) ((decodeN) | ((popN) << 5) | ((pushN) << 7))
+#define RDI_DECODEN_FROM_CTRLBITS(ctrlbits)   ((ctrlbits) & 0x1f)
+#define RDI_POPN_FROM_CTRLBITS(ctrlbits)      (((ctrlbits) >> 5) & 0x3)
+#define RDI_PUSHN_FROM_CTRLBITS(ctrlbits)     (((ctrlbits) >> 7) & 0x1)
 #define RDI_EncodeRegReadParam(reg,bytesize,bytepos) ((reg)|((bytesize)<<8)|((bytepos)<<16))
 ```