vm/code_block_visitor.hpp

   1 namespace factor
   2 {
   3
   4 /* Code block visitors iterate over sets of code blocks, applying a functor to
   5 each one. The functor returns a new code_block pointer, which may or may not
   6 equal the old one. This is stored back to the original location.
   7
   8 This is used by GC's sweep and compact phases, and the implementation of the
   9 modify-code-heap primitive.
  10
  11 Iteration is driven by visit_*() methods. Some of them define GC roots:
  12 - visit_context_code_blocks()
  13 - visit_callback_code_blocks() */
  14
  15 template<typename Fixup> struct code_block_visitor {
  16         factor_vm *parent;
  17         Fixup fixup;
  18
  19         explicit code_block_visitor(factor_vm *parent_, Fixup fixup_) :
  20                 parent(parent_), fixup(fixup_) {}
  21
  22         code_block *visit_code_block(code_block *compiled);
  23         void visit_object_code_block(object *obj);
  24         void visit_embedded_code_pointers(code_block *compiled);
  25         void visit_context_code_blocks();
  26         void visit_uninitialized_code_blocks();
  27
  28         void visit_code_roots();
  29 };
  30
  31 template<typename Fixup>
  32 code_block *code_block_visitor<Fixup>::visit_code_block(code_block *compiled)
  33 {
  34         return fixup.fixup_code(compiled);
  35 }
  36
  37 template<typename Fixup>
  38 struct call_frame_code_block_visitor {
  39         factor_vm *parent;
  40         Fixup fixup;
  41
  42         explicit call_frame_code_block_visitor(factor_vm *parent_, Fixup fixup_) :
  43                 parent(parent_), fixup(fixup_) {}
  44
  45         void operator()(stack_frame *frame)
  46         {
  47                 cell offset = parent->frame_offset(frame);
  48                 code_block *compiled = fixup.fixup_code(parent->frame_code(frame));
  49                 frame->entry_point = compiled->entry_point();
  50                 parent->set_frame_offset(frame,offset);
  51         }
  52 };
  53
  54 template<typename Fixup>
  55 void code_block_visitor<Fixup>::visit_object_code_block(object *obj)
  56 {
  57         switch(obj->type())
  58         {
  59         case WORD_TYPE:
  60                 {
  61                         word *w = (word *)obj;
  62                         if(w->code)
  63                                 w->code = visit_code_block(w->code);
  64                         if(w->counting_profiler)
  65                                 w->counting_profiler = visit_code_block(w->counting_profiler);
  66
  67                         parent->update_word_entry_point(w);
  68                         break;
  69                 }
  70         case QUOTATION_TYPE:
  71                 {
  72                         quotation *q = (quotation *)obj;
  73                         if(q->code)
  74                                 parent->set_quot_entry_point(q,visit_code_block(q->code));
  75                         break;
  76                 }
  77         case CALLSTACK_TYPE:
  78                 {
  79                         callstack *stack = (callstack *)obj;
  80                         call_frame_code_block_visitor<Fixup> call_frame_visitor(parent,fixup);
  81                         parent->iterate_callstack_object(stack,call_frame_visitor);
  82                         break;
  83                 }
  84         }
  85 }
  86
  87 template<typename Fixup>
  88 struct embedded_code_pointers_visitor {
  89         Fixup fixup;
  90
  91         explicit embedded_code_pointers_visitor(Fixup fixup_) : fixup(fixup_) {}
  92
  93         void operator()(instruction_operand op)
  94         {
  95                 relocation_type type = op.rel_type();
  96                 if(type == RT_ENTRY_POINT
  97                         || type == RT_ENTRY_POINT_PIC
  98                         || type == RT_ENTRY_POINT_PIC_TAIL)
  99                         op.store_code_block(fixup.fixup_code(op.load_code_block()));
 100         }
 101 };
 102
 103 template<typename Fixup>
 104 void code_block_visitor<Fixup>::visit_embedded_code_pointers(code_block *compiled)
 105 {
 106         if(!parent->code->uninitialized_p(compiled))
 107         {
 108                 embedded_code_pointers_visitor<Fixup> operand_visitor(fixup);
 109                 compiled->each_instruction_operand(operand_visitor);
 110         }
 111 }
 112
 113 template<typename Fixup>
 114 void code_block_visitor<Fixup>::visit_context_code_blocks()
 115 {
 116         call_frame_code_block_visitor<Fixup> call_frame_visitor(parent,fixup);
 117         parent->iterate_active_callstacks(call_frame_visitor);
 118 }
 119
 120 template<typename Fixup>
 121 void code_block_visitor<Fixup>::visit_uninitialized_code_blocks()
 122 {
 123         std::map<code_block *, cell> *uninitialized_blocks = &parent->code->uninitialized_blocks;
 124         std::map<code_block *, cell>::const_iterator iter = uninitialized_blocks->begin();
 125         std::map<code_block *, cell>::const_iterator end = uninitialized_blocks->end();
 126
 127         std::map<code_block *, cell> new_uninitialized_blocks;
 128         for(; iter != end; iter++)
 129         {
 130                 new_uninitialized_blocks.insert(std::make_pair(
 131                         fixup.fixup_code(iter->first),
 132                         iter->second));
 133         }
 134
 135         parent->code->uninitialized_blocks = new_uninitialized_blocks;
 136 }
 137
 138 template<typename Fixup>
 139 void code_block_visitor<Fixup>::visit_code_roots()
 140 {
 141         visit_uninitialized_code_blocks();
 142 }
 143
 144 }