tear off contexts when invoking a continuation

lib/cont.c

@@ -44,6 +44,8 @@ pic_save_point(pic_state *pic, struct cont *cont, PIC_JMPBUF *jmp)
 void
 pic_load_point(pic_state *pic, struct cont *cont)
 {
+  pic_vm_tear_off(pic);
+
   /* load runtime context */
   pic->sp = pic->stbase + cont->sp_offset;
   pic->ci = pic->cibase + cont->ci_offset;

lib/state.h

@@ -74,6 +74,8 @@ void pic_heap_close(pic_state *, struct heap *);
 pic_value pic_global_ref(pic_state *pic, pic_value uid);
 void pic_global_set(pic_state *pic, pic_value uid, pic_value value);
 
+void pic_vm_tear_off(pic_state *pic);
+
 #if defined(__cplusplus)
 }
 #endif

lib/vm.h

@@ -10,46 +10,46 @@ extern "C" {
 #endif
 
 enum {
-  OP_NOP,
-  OP_POP,
-  OP_PUSHUNDEF,
-  OP_PUSHNIL,
-  OP_PUSHTRUE,
-  OP_PUSHFALSE,
-  OP_PUSHINT,
-  OP_PUSHFLOAT,
-  OP_PUSHCHAR,
-  OP_PUSHEOF,
-  OP_PUSHCONST,
-  OP_GREF,
-  OP_GSET,
-  OP_LREF,
-  OP_LSET,
-  OP_CREF,
-  OP_CSET,
-  OP_JMP,
-  OP_JMPIF,
-  OP_NOT,
-  OP_CALL,
-  OP_TAILCALL,
-  OP_RET,
-  OP_LAMBDA,
-  OP_CONS,
-  OP_CAR,
-  OP_CDR,
-  OP_NILP,
-  OP_SYMBOLP,
-  OP_PAIRP,
-  OP_ADD,
-  OP_SUB,
-  OP_MUL,
-  OP_DIV,
-  OP_EQ,
-  OP_LT,
-  OP_LE,
-  OP_GT,
-  OP_GE,
-  OP_STOP
+  OP_NOP       = 0,
+  OP_POP       = 1,
+  OP_PUSHUNDEF = 2,
+  OP_PUSHNIL   = 3,
+  OP_PUSHTRUE  = 4,
+  OP_PUSHFALSE = 5,
+  OP_PUSHINT   = 6,
+  OP_PUSHFLOAT = 7,
+  OP_PUSHCHAR  = 8,
+  OP_PUSHEOF   = 9,
+  OP_PUSHCONST = 10,
+  OP_GREF      = 11,
+  OP_GSET      = 12,
+  OP_LREF      = 13,
+  OP_LSET      = 14,
+  OP_CREF      = 15,
+  OP_CSET      = 16,
+  OP_JMP       = 17,
+  OP_JMPIF     = 18,
+  OP_NOT       = 19,
+  OP_CALL      = 20,
+  OP_TAILCALL  = 21,
+  OP_RET       = 22,
+  OP_LAMBDA    = 23,
+  OP_CONS      = 24,
+  OP_CAR       = 25,
+  OP_CDR       = 26,
+  OP_NILP      = 27,
+  OP_SYMBOLP   = 28,
+  OP_PAIRP     = 29,
+  OP_ADD       = 30,
+  OP_SUB       = 31,
+  OP_MUL       = 32,
+  OP_DIV       = 33,
+  OP_EQ        = 34,
+  OP_LT        = 35,
+  OP_LE        = 36,
+  OP_GT        = 37,
+  OP_GE        = 38,
+  OP_STOP      = 39
 };
 
 #if defined(__cplusplus)