Update func env representation to not store envs in function

objects.

src/assembler/asm.c

@@ -187,17 +187,19 @@ static int32_t dst_asm_addenv(DstAssembler *a, Dst envname) {
     int32_t envindex;
     int32_t res;
     if (dst_equals(a->name, envname)) {
-        return 0;
+        return -1;
     }
     /* Check for memoized value */
     check = dst_table_get(&a->envs, envname);
-    if (dst_checktype(check, DST_INTEGER)) return dst_unwrap_integer(check);
+    if (dst_checktype(check, DST_INTEGER)) {
-    if (NULL == a->parent) return -1;
+        return dst_unwrap_integer(check);
+    }
+    if (NULL == a->parent) return -2;
     res = dst_asm_addenv(a->parent, envname);
-    if (res < 0)
+    if (res < -1) {
         return res;
+    }
     envindex = def->environments_length;
-    if (envindex == 0) envindex = 1;
     dst_table_put(&a->envs, envname, dst_wrap_integer(envindex));
     if (envindex >= a->environments_capacity) {
         int32_t newcap = 2 * envindex;
@@ -291,7 +293,7 @@ static int32_t doarg_1(
             if (argtype == DST_OAT_ENVIRONMENT && ret == -1) {
                 /* Add a new env */
                 ret = dst_asm_addenv(a, x);
-                if (ret < 0) {
+                if (ret < -1) {
                     dst_asm_errorv(a, dst_formatc("unknown environment %q", x));
                 }
             }
@@ -788,7 +790,6 @@ Dst dst_disasm(DstFuncDef *def) {
     DstArray *bcode = dst_array(def->bytecode_length);
     DstArray *constants;
     DstTable *ret = dst_table(10);
-    if (def->arity)
     dst_table_put(ret, dst_csymbolv("arity"), dst_wrap_integer(def->arity));
     dst_table_put(ret, dst_csymbolv("bytecode"), dst_wrap_array(bcode));
     if (NULL != def->sourcepath) {
@@ -871,7 +872,7 @@ int dst_asm_cfun(DstArgs args) {
     if (args.n < 1) return dst_throw(args, "expected assembly source");
     res = dst_asm(args.v[0], 0);
     if (res.status == DST_ASSEMBLE_OK) {
-        return dst_return(args, dst_wrap_function(dst_function(res.funcdef, NULL)));
+        return dst_return(args, dst_wrap_function(dst_thunk(res.funcdef)));
     } else {
         return dst_throwv(args, dst_wrap_string(res.error));
     }

src/compiler/compile.c

@@ -132,7 +132,7 @@ int32_t dstc_lslotn(DstCompiler *c, int32_t max, int32_t nth) {
 /* Free a slot */
 void dstc_freeslot(DstCompiler *c, DstSlot s) {
     if (s.flags & (DST_SLOT_CONSTANT | DST_SLOT_REF | DST_SLOT_NAMED)) return;
-    if (s.envindex > 0) return;
+    if (s.envindex >= 0) return;
     dstc_sfreei(c, s.index);
 }
 
@@ -208,7 +208,7 @@ void dstc_popscope(DstCompiler *c) {
 /* Leave a scope but keep a slot allocated. */
 void dstc_popscope_keepslot(DstCompiler *c, DstSlot retslot) {
     dstc_popscope(c);
-    if (retslot.envindex == 0 && retslot.index >= 0) {
+    if (retslot.envindex < 0 && retslot.index >= 0) {
         slotalloci(c, retslot.index);
     }
 }
@@ -219,7 +219,7 @@ DstSlot dstc_cslot(Dst x) {
     ret.flags = (1 << dst_type(x)) | DST_SLOT_CONSTANT;
     ret.index = -1;
     ret.constant = x;
-    ret.envindex = 0;
+    ret.envindex = -1;
     return ret;
 }
 
@@ -285,7 +285,7 @@ DstSlot dstc_resolve(
 
     /* Unused references and locals shouldn't add captured envs. */
     if (unused || foundlocal) {
-        ret.envindex = 0;
+        ret.envindex = -1;
         return ret;
     }
 
@@ -294,18 +294,17 @@ DstSlot dstc_resolve(
     while (scope >= c->scopes && !(scope->flags & DST_SCOPE_FUNCTION)) scope--;
     dst_assert(scope >= c->scopes, "invalid scopes");
     scope->flags |= DST_SCOPE_ENV;
-    if (!dst_v_count(scope->envs)) dst_v_push(scope->envs, 0);
     scope++;
 
     /* Propogate env up to current scope */
-    int32_t envindex = 0;
+    int32_t envindex = -1;
     while (scope <= top) {
         if (scope->flags & DST_SCOPE_FUNCTION) {
             int32_t j, len;
             int scopefound = 0;
             /* Check if scope already has env. If so, break */
             len = dst_v_count(scope->envs);
-            for (j = 1; j < len; j++) {
+            for (j = 0; j < len; j++) {
                 if (scope->envs[j] == envindex) {
                     scopefound = 1;
                     envindex = j;
@@ -314,7 +313,6 @@ DstSlot dstc_resolve(
             }
             /* Add the environment if it is not already referenced */
             if (!scopefound) {
-                if (!dst_v_count(scope->envs)) dst_v_push(scope->envs, 0);
                 len = dst_v_count(scope->envs);
                 dst_v_push(scope->envs, envindex);
                 envindex = len;
@@ -418,7 +416,7 @@ int32_t dstc_preread(
                     (ret << 8) |
                     DOP_GET_INDEX);
         }
-    } else if (s.envindex > 0 || s.index > max) {
+    } else if (s.envindex >= 0 || s.index > max) {
         ret = dstc_lslotn(c, max, nth);
         dstc_emit(c, ast, 
                 ((uint32_t)(s.index) << 24) |
@@ -440,7 +438,7 @@ int32_t dstc_preread(
 
 /* Call this to release a read handle after emitting the instruction. */
 void dstc_postread(DstCompiler *c, DstSlot s, int32_t index) {
-    if (index != s.index || s.envindex > 0 || s.flags & DST_SLOT_CONSTANT) {
+    if (index != s.index || s.envindex >= 0 || s.flags & DST_SLOT_CONSTANT) {
         /* We need to free the temporary slot */
         dstc_sfreei(c, index);
     }
@@ -495,7 +493,7 @@ void dstc_copy(
     /* far index */
 
     /* If dest is a near index, do some optimization */
-    if (dest.envindex == 0 && dest.index >= 0 && dest.index <= 0xFF) {
+    if (dest.envindex < 0 && dest.index >= 0 && dest.index <= 0xFF) {
         if (src.flags & DST_SLOT_CONSTANT) {
             dstc_loadconst(c, ast, src.constant, dest.index);
         } else if (src.flags & DST_SLOT_REF) {
@@ -504,7 +502,7 @@ void dstc_copy(
                     (dest.index << 16) |
                     (dest.index << 8) |
                     DOP_GET_INDEX);
-        } else if (src.envindex > 0) {
+        } else if (src.envindex >= 0) {
             dstc_emit(c, ast,
                     (src.index << 24) |
                     (src.envindex << 16) |
@@ -533,7 +531,7 @@ void dstc_copy(
                 (dstc_const(c, ast, dest.constant) << 16) |
                 (reflocal << 8) |
                 DOP_LOAD_CONSTANT);
-    } else if (dest.envindex > 0) {
+    } else if (dest.envindex >= 0) {
         writeback = 2;
         destlocal = srclocal;
     } else if (dest.index > 0xFF) {
@@ -597,11 +595,11 @@ DstSlot dstc_return(DstCompiler *c, DstAst *ast, DstSlot s) {
 DstSlot dstc_gettarget(DstFopts opts) {
     DstSlot slot;
     if ((opts.flags & DST_FOPTS_HINT) &&
-        (opts.hint.envindex == 0) &&
+        (opts.hint.envindex < 0) &&
         (opts.hint.index >= 0 && opts.hint.index <= 0xFF)) {
         slot = opts.hint;
     } else {
-        slot.envindex = 0;
+        slot.envindex = -1;
         slot.constant = dst_wrap_nil();
         slot.flags = 0;
         slot.index = dstc_lslotn(opts.compiler, 0xFF, 4);
@@ -883,7 +881,7 @@ DstFuncDef *dstc_pop_funcdef(DstCompiler *c) {
 
     /* Copy envs */
     def->environments_length = dst_v_count(scope.envs);
-    if (def->environments_length > 1) def->environments = dst_v_flatten(scope.envs);
+    def->environments = dst_v_flatten(scope.envs);
 
     def->constants_length = dst_v_count(scope.consts);
     def->constants = dst_v_flatten(scope.consts);
@@ -926,9 +924,6 @@ DstFuncDef *dstc_pop_funcdef(DstCompiler *c) {
     def->flags = 0;
     if (scope.flags & DST_SCOPE_ENV) {
         def->flags |= DST_FUNCDEF_FLAG_NEEDSENV;
-        if (def->environments_length == 0) {
-            def->environments_length = 1;
-        }
     }
 
     /* Pop the scope */
@@ -1001,7 +996,7 @@ int dst_compile_cfun(DstArgs args) {
     env = dst_unwrap_table(args.v[1]);
     res = dst_compile(args.v[0], env, 0);
     if (res.status == DST_COMPILE_OK) {
-        DstFunction *fun = dst_function(res.funcdef, NULL);
+        DstFunction *fun = dst_thunk(res.funcdef);
         return dst_return(args, dst_wrap_function(fun));
     } else {
         t = dst_table(2);

src/compiler/run.c

@@ -40,7 +40,7 @@ int dst_dobytes(DstTable *env, const uint8_t *bytes, int32_t len) {
                     Dst form = dst_parser_produce(&parser);
                     DstCompileResult cres = dst_compile(form, env, 0);
                     if (cres.status == DST_COMPILE_OK) {
-                        DstFunction *f = dst_function(cres.funcdef, NULL);
+                        DstFunction *f = dst_thunk(cres.funcdef);
                         Dst ret;
                         if (dst_run(dst_wrap_function(f), &ret)) {
                             printf("internal runtime error: %s\n", (const char *) dst_to_string(ret));

src/compiler/specials.c

@@ -90,7 +90,7 @@ static void destructure(DstCompiler *c, Dst left, DstSlot right,
                         dstc_postread(c, islot, locali);
                     }
                     newright.index = localsub;
-                    newright.envindex = 0;
+                    newright.envindex = -1;
                     newright.constant = dst_wrap_nil();
                     newright.flags = DST_SLOTTYPE_ANY;
                     /* Traverse into the structure */
@@ -120,7 +120,7 @@ static void destructure(DstCompiler *c, Dst left, DstSlot right,
                             DOP_GET);
                     dstc_postread(c, kslot, localk);
                     newright.index = localsub;
-                    newright.envindex = 0;
+                    newright.envindex = -1;
                     newright.constant = dst_wrap_nil();
                     newright.flags = DST_SLOTTYPE_ANY;
                     /* Traverse into the structure */
@@ -197,7 +197,7 @@ static DstSlot dohead(DstCompiler *c, DstFopts opts, DstAst *ast, Dst *head, int
 static DstSlot namelocal(DstCompiler *c, DstAst *ast, Dst head, int32_t flags, DstSlot ret) {
     /* Non root scope, bring to local slot */
     if (ret.flags & DST_SLOT_NAMED ||
-            ret.envindex != 0 ||
+            ret.envindex >= 0 ||
             ret.index < 0 ||
             ret.index > 0xFF) {
         /* Slot is not able to be named */
@@ -205,7 +205,7 @@ static DstSlot namelocal(DstCompiler *c, DstAst *ast, Dst head, int32_t flags, D
         localslot.index = dstc_lsloti(c);
         /* infer type? */
         localslot.flags = flags;
-        localslot.envindex = 0;
+        localslot.envindex = -1;
         localslot.constant = dst_wrap_nil();
         dstc_copy(c, ast, localslot, ret);
         ret = localslot;
@@ -546,7 +546,7 @@ DstSlot dstc_fn(DstFopts opts, DstAst *ast, int32_t argn, const Dst *argv) {
                     continue;
                 }
                 slot.flags = DST_SLOT_NAMED;
-                slot.envindex = 0;
+                slot.envindex = -1;
                 slot.constant = dst_wrap_nil();
                 slot.index = dstc_lsloti(c);
                 dstc_nameslot(c, dst_unwrap_symbol(param), slot);
@@ -564,7 +564,7 @@ DstSlot dstc_fn(DstFopts opts, DstAst *ast, int32_t argn, const Dst *argv) {
     /* Check for self ref */
     if (selfref) {
         DstSlot slot;
-        slot.envindex = 0;
+        slot.envindex = -1;
         slot.flags = DST_SLOT_NAMED | DST_FUNCTION;
         slot.constant = dst_wrap_nil();
         slot.index = dstc_lsloti(c);

src/core/bytecode.c

@@ -221,26 +221,11 @@ DstFuncDef *dst_funcdef_alloc() {
     return def;
 }
 
-/* Create a closure from a funcdef and a parent function */
+/* Create a simple closure from a funcdef */
-DstFunction *dst_function(DstFuncDef *def, DstFunction *parent) {
+DstFunction *dst_thunk(DstFuncDef *def) {
-    int32_t i;
     DstFunction *func = dst_gcalloc(DST_MEMORY_FUNCTION, sizeof(DstFunction));
-    int32_t elen = def->environments_length;
     func->def = def;
-    if (elen) {
-        func->envs = malloc(sizeof(DstFuncEnv *) * elen);
-        if (elen > 1 && !parent) return NULL;
-        if (NULL == func->envs) {
-            DST_OUT_OF_MEMORY;
-        }
-        func->envs[0] = NULL;
-    } else {
     func->envs = NULL;
-    }
-    for (i = 1; i < def->environments_length; ++i) {
-        int32_t inherit = def->environments[i];
-        func->envs[i] = parent->envs[inherit];
-    }
     return func;
 }
 
@@ -256,5 +241,5 @@ DstFunction *dst_quick_asm(int32_t arity, int varargs, int32_t slots, const uint
         DST_OUT_OF_MEMORY;
     }
     memcpy(def->bytecode, bytecode, bytecode_size);
-    return dst_function(def, NULL);
+    return dst_thunk(def);
 }

src/core/fiber.c

@@ -101,19 +101,6 @@ void dst_fiber_pushn(DstFiber *fiber, const Dst *arr, int32_t n) {
     fiber->stacktop = newtop;
 }
 
-/* Help set up function */
-static void funcframe_env(DstFiber *fiber, DstFunction *func) {
-    /* Check closure env */
-    if (func->def->flags & DST_FUNCDEF_FLAG_NEEDSENV) {
-        /* Delayed capture of current stack frame */
-        DstFuncEnv *env = dst_gcalloc(DST_MEMORY_FUNCENV, sizeof(DstFuncEnv));
-        env->offset = fiber->frame;
-        env->as.fiber = fiber;
-        env->length = func->def->slotcount;
-        func->envs[0] = env;
-    }
-}
-
 /* Push a stack frame to a fiber */
 void dst_fiber_funcframe(DstFiber *fiber, DstFunction *func) {
     DstStackFrame *newframe;
@@ -140,6 +127,7 @@ void dst_fiber_funcframe(DstFiber *fiber, DstFunction *func) {
     newframe->prevframe = oldframe;
     newframe->pc = func->def->bytecode;
     newframe->func = func;
+    newframe->env = NULL;
 
     /* Check varargs */
     if (func->def->flags & DST_FUNCDEF_FLAG_VARARG) {
@@ -152,17 +140,13 @@ void dst_fiber_funcframe(DstFiber *fiber, DstFunction *func) {
                 oldtop - tuplehead));
         }
     }
-
-    /* Check env */
-    funcframe_env(fiber, func) ;
 }
 
 /* If a frame has a closure environment, detach it from
  * the stack and have it keep its own values */
-static void dst_function_detach(DstFunction *func) {
+static void dst_env_detach(DstFuncEnv *env) {
     /* Check for closure environment */
-    if (NULL != func->envs && NULL != func->envs[0]) {
+    if (env) {
-        DstFuncEnv *env = func->envs[0];
         size_t s = sizeof(Dst) * env->length;
         Dst *vmem = malloc(s);
         if (NULL == vmem) {
@@ -190,7 +174,8 @@ void dst_fiber_funcframe_tail(DstFiber *fiber, DstFunction *func) {
 
     /* Detatch old function */
     if (NULL != dst_fiber_frame(fiber)->func)
-        dst_function_detach(dst_fiber_frame(fiber)->func);
+        dst_env_detach(dst_fiber_frame(fiber)->env);
+    dst_fiber_frame(fiber)->env = NULL;
 
     /* Check varargs */
     if (func->def->flags & DST_FUNCDEF_FLAG_VARARG) {
@@ -218,9 +203,6 @@ void dst_fiber_funcframe_tail(DstFiber *fiber, DstFunction *func) {
     /* Set stack stuff */
     fiber->stacktop = fiber->stackstart = nextstacktop;
 
-    /* Varargs and func envs */
-    funcframe_env(fiber, func);
-
     /* Set frame stuff */
     dst_fiber_frame(fiber)->func = func;
     dst_fiber_frame(fiber)->pc = func->def->bytecode;
@@ -257,7 +239,7 @@ void dst_fiber_popframe(DstFiber *fiber) {
     
     /* Clean up the frame (detach environments) */
     if (NULL != frame->func)
-        dst_function_detach(frame->func);
+        dst_env_detach(frame->env);
 
     /* Shrink stack */
     fiber->stacktop = fiber->stackstart = fiber->frame;

src/core/gc.c

@@ -186,6 +186,8 @@ static void dst_mark_fiber(DstFiber *fiber) {
         frame = (DstStackFrame *)(fiber->data + i - DST_FRAME_SIZE);
         if (NULL != frame->func)
             dst_mark_function(frame->func);
+        if (NULL != frame->env)
+            dst_mark_funcenv(frame->env);
         /* Mark all values in the stack frame */
         dst_mark_many(fiber->data + i, j - i);
         j = i - DST_FRAME_SIZE;

src/core/vm.c

@@ -494,9 +494,40 @@ static void *op_lookup[255] = {
     VM_OP(DOP_CLOSURE)
     {
         DstFuncDef *fd;
+        DstFunction *fn;
         vm_assert((int32_t)oparg(2, 0xFFFF) < func->def->defs_length, "invalid funcdef");
         fd = func->def->defs[(int32_t)oparg(2, 0xFFFF)];
-        stack[oparg(1, 0xFF)] = dst_wrap_function(dst_function(fd, func));
+        fn = dst_thunk(fd);
+        {
+            int32_t elen = fd->environments_length;
+            if (elen) {
+                int32_t i;
+                fn->envs = malloc(sizeof(DstFuncEnv *) * elen);
+                if (NULL == fn->envs) {
+                    DST_OUT_OF_MEMORY;
+                }
+                for (i = 0; i < elen; ++i) {
+                    int32_t inherit = fd->environments[i];
+                    if (inherit == -1) {
+                        DstStackFrame *frame = (DstStackFrame *)stack - 1;
+                        if (!frame->env) {
+                            /* Lazy capture of current stack frame */
+                            DstFuncEnv *env = dst_gcalloc(DST_MEMORY_FUNCENV, sizeof(DstFuncEnv));
+                            env->offset = dst_vm_fiber->frame;
+                            env->as.fiber = dst_vm_fiber;
+                            env->length = func->def->slotcount;
+                            frame->env = env;
+                        }
+                        fn->envs[i] = frame->env;
+                    } else {
+                        fn->envs[i] = func->envs[inherit];
+                    }
+                }
+            } else {
+                fn->envs = NULL;
+            }
+        }
+        stack[oparg(1, 0xFF)] = dst_wrap_function(fn);
         pc++;
         vm_checkgc_next();
     }
@@ -743,10 +774,10 @@ static void *op_lookup[255] = {
 /* Run the vm with a given function. This function is
  * called to start the vm. */
 int dst_run(Dst callee, Dst *returnreg) {
-    if (NULL == dst_vm_fiber) {
+    if (dst_vm_fiber) {
-        dst_vm_fiber = dst_fiber(0);
-    } else {
        dst_fiber_reset(dst_vm_fiber); 
+    } else {
+        dst_vm_fiber = dst_fiber(64);
     }
     if (dst_checktype(callee, DST_CFUNCTION)) {
         DstArgs args;
@@ -772,7 +803,7 @@ int dst_call(Dst callee, Dst *returnreg, int32_t argn, const Dst *argv) {
     int lock;
     DstFiber *oldfiber = dst_vm_fiber;
     lock = dst_vm_gc_suspend++;
-    dst_vm_fiber = dst_fiber(0);
+    dst_vm_fiber = dst_fiber(64);
     dst_fiber_pushn(dst_vm_fiber, argv, argn);
     if (dst_checktype(callee, DST_CFUNCTION)) {
         DstArgs args;

src/include/dst/dst.h

@@ -172,7 +172,7 @@ int dst_gcunrootall(Dst root);
 
 /* Functions */
 DstFuncDef *dst_funcdef_alloc(void);
-DstFunction *dst_function(DstFuncDef *def, DstFunction *parent);
+DstFunction *dst_thunk(DstFuncDef *def);
 int dst_verify(DstFuncDef *def);
 DstFunction *dst_quick_asm(int32_t arity, int varargs, int32_t slots, const uint32_t *bytecode, size_t bytecode_size);
 

src/include/dst/dsttypes.h

@@ -328,6 +328,7 @@ struct DstStackFrame {
     DstFunction *func;
     uint32_t *pc;
     int32_t prevframe;
+    DstFuncEnv *env;
 };
 
 /* Number of Dsts a frame takes up in the stack */