remove NULL check on destination/target thunk

interpreter/code.c

@@ -14,11 +14,8 @@
 
 #define forward_thunk(thunk, frame_ptr) \
         Thunk* dst = get_dst(frame_ptr); \
-        if(dst != NULL) \
-        { \
-            dst->desc = (Desc*) __FORWARD_PTR__; \
-            dst->_forward_ptr = thunk; \
-        }
+        dst->desc = (Desc*) __FORWARD_PTR__; \
+        dst->_forward_ptr = thunk; 
 
 #define arg_from_thunk(descarg, arg) \
         if(((FunEntry*) (descarg))->strictness & argmask && !arg->desc->hnf) \
@@ -340,9 +337,11 @@ void exec(Code* expr, int frame_ptr, int root_frame_ptr)
         }
         case CT_SELECT:
         {
-            push_a(NULL);
+            Thunk* pattern = alloc_b();
+            pattern->desc = (Desc*) __STACK_PLACEHOLDER__;
+            push_a(pattern);
             exec(((SelectEntry*) expr)->expr, frame_ptr, stack_top_a);
-            Thunk* pattern = pop_a();
+            pattern = pop_a();
 
             assert(is_hnf(pattern));
             assert(pattern->desc->type == FT_ADT);            

interpreter/main.c

@@ -83,10 +83,12 @@ int main ( int argc, char *argv[] )
     struct timeval t1, t2;
     gettimeofday(&t1, NULL);
 #endif
-            
-    push_a(NULL);
+
+    Thunk* res = alloc_b();
+    res->desc = (Desc*) __STACK_PLACEHOLDER__;
+    push_a(res);
     exec(expr, stack_top_a, stack_top_a);    
-    Thunk* res = pop_a();
+    res = pop_a();
 
 #ifdef BENCHMARK
     gettimeofday(&t2, NULL);

interpreter/prim.c

@@ -8,39 +8,45 @@
 #define arg(idx) stack_a[stack_top_a - idx]
 
 void __add(int frame_ptr) {
-    set_return(frame_ptr, updateI(get_dst(frame_ptr), readI(arg(2)) + readI(arg(1))));
+    Thunk* target = get_dst(frame_ptr);
+    target->desc = (Desc*) __INT__;
+    target->_int = readI(arg(2)) + readI(arg(1));
 }
 
 void __sub(int frame_ptr) {
-    set_return(frame_ptr, updateI(get_dst(frame_ptr), readI(arg(2)) - readI(arg(1))));
+    Thunk* target = get_dst(frame_ptr);
+    target->desc = (Desc*) __INT__;
+    target->_int = readI(arg(2)) - readI(arg(1));
 }
 
 void __gt(int frame_ptr) {
-    set_return(frame_ptr, updateB(get_dst(frame_ptr), readI(arg(2)) > readI(arg(1))));
+    Thunk* target = get_dst(frame_ptr);
+    target->desc = (Desc*) __BOOL__;
+    target->_bool = readI(arg(2)) > readI(arg(1));
 }
 
 void __lt(int frame_ptr) {
-    set_return(frame_ptr, updateB(get_dst(frame_ptr), readI(arg(2)) < readI(arg(1))));
+    Thunk* target = get_dst(frame_ptr);
+    target->desc = (Desc*) __BOOL__;
+    target->_bool = readI(arg(2)) < readI(arg(1));
 }
 
 void __eqI(int frame_ptr) {
-    Thunk* arg1 = arg(2);
-    Thunk* arg2 = arg(1);
-
-    set_return(frame_ptr, updateB(get_dst(frame_ptr), readI(arg1) == readI(arg2)));
+    Thunk* target = get_dst(frame_ptr);
+    target->desc = (Desc*) __BOOL__;
+    target->_bool = readI(arg(2)) == readI(arg(1));
 }
 
 void __eqB(int frame_ptr) {
-    Thunk* arg1 = arg(2);
-    Thunk* arg2 = arg(1);
-
-    set_return(frame_ptr, updateB(get_dst(frame_ptr), readB(arg1) == readB(arg2)));
+    Thunk* target = get_dst(frame_ptr);
+    target->desc = (Desc*) __BOOL__;
+    target->_bool = readB(arg(2)) == readB(arg(1));
 }
 
 void __not(int frame_ptr) {
-    Thunk* arg1 = arg(1);
-
-    set_return(frame_ptr, updateB(get_dst(frame_ptr), !readB(arg1)));
+    Thunk* target = get_dst(frame_ptr);
+    target->desc = (Desc*) __BOOL__;
+    target->_bool = !readB(arg(1));
 }
 
 void add_prim(int arity, int strictness, char* name, void (*exec)(int)) {

interpreter/thunk.c

@@ -35,8 +35,6 @@ int readB(Thunk* thunk) {
 #endif
 
 struct Thunk* updateI(Thunk* target, int i) {
-    if (target == NULL) target = (Thunk*) alloc_heap(sizeof (Thunk));
-
     // always can be overwritten with boxed integer
     target->desc = (Desc*) __INT__;
     target->_int = i;
@@ -44,8 +42,6 @@ struct Thunk* updateI(Thunk* target, int i) {
 }
 
 struct Thunk* updateB(Thunk* target, int b) {
-    if (target == NULL) target = (Thunk*) alloc_heap(sizeof (Thunk));
-    
     // always can be overwritten with boxed integer
     target->desc = (Desc*) __BOOL__;
     target->_bool = b;
@@ -53,8 +49,6 @@ struct Thunk* updateB(Thunk* target, int b) {
 }
 
 struct Thunk* updateT(Thunk* target, Thunk* source) {
-    if (target == NULL) target = (Thunk*) alloc_heap(sizeof (Thunk));
-    
     memcpy(target, source, sizeof(Thunk));
     return target;
 }
@@ -65,14 +59,10 @@ struct Thunk* updateF(Thunk* target, Desc* f) {
     Thunk* thunk = target;
     int newsize = f->thunk_size;
         
-    if (thunk == NULL) {
+    if (target->desc->thunk_size < newsize) {
         thunk = (Thunk*) alloc_heap(newsize);
-    } else {
-        if (target->desc->thunk_size < newsize) {
-            thunk = (Thunk*) alloc_heap(newsize);
-            target->desc = (Desc*) __FORWARD_PTR__;
-            target->_forward_ptr = thunk;
-        }
+        target->desc = (Desc*) __FORWARD_PTR__;
+        target->_forward_ptr = thunk;
     }
 
     assert(thunk != NULL);