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
  29 template<typename Fixup>
  30 code_block *code_block_visitor<Fixup>::visit_code_block(code_block *compiled)
  31 {
  32         return fixup.fixup_code(compiled);
  33 }
  34
  35 template<typename Fixup>
  36 struct call_frame_code_block_visitor {
  37         factor_vm *parent;
  38         Fixup fixup;
  39
  40         explicit call_frame_code_block_visitor(factor_vm *parent_, Fixup fixup_) :
  41                 parent(parent_), fixup(fixup_) {}
  42
  43         void operator()(stack_frame *frame)
  44         {
  45                 cell offset = parent->frame_offset(frame);
  46                 code_block *compiled = fixup.fixup_code(parent->frame_code(frame));
  47                 frame->entry_point = compiled->entry_point();
  48                 parent->set_frame_offset(frame,offset);
  49         }
  50 };
  51
  52 template<typename Fixup>
  53 void code_block_visitor<Fixup>::visit_object_code_block(object *obj)
  54 {
  55         switch(obj->type())
  56         {
  57         case WORD_TYPE:
  58                 {
  59                         word *w = (word *)obj;
  60                         if(w->code)
  61                                 w->code = visit_code_block(w->code);
  62                         if(w->profiling)
  63                                 w->profiling = visit_code_block(w->profiling);
  64
  65                         parent->update_word_entry_point(w);
  66                         break;
  67                 }
  68         case QUOTATION_TYPE:
  69                 {
  70                         quotation *q = (quotation *)obj;
  71                         if(q->code)
  72                                 parent->set_quot_entry_point(q,visit_code_block(q->code));
  73                         break;
  74                 }
  75         case CALLSTACK_TYPE:
  76                 {
  77                         callstack *stack = (callstack *)obj;
  78                         call_frame_code_block_visitor<Fixup> call_frame_visitor(parent,fixup);
  79                         parent->iterate_callstack_object(stack,call_frame_visitor);
  80                         break;
  81                 }
  82         }
  83 }
  84
  85 template<typename Fixup>
  86 struct embedded_code_pointers_visitor {
  87         Fixup fixup;
  88
  89         explicit embedded_code_pointers_visitor(Fixup fixup_) : fixup(fixup_) {}
  90
  91         void operator()(instruction_operand op)
  92         {
  93                 relocation_type type = op.rel_type();
  94                 if(type == RT_ENTRY_POINT
  95                         || type == RT_ENTRY_POINT_PIC
  96                         || type == RT_ENTRY_POINT_PIC_TAIL)
  97                         op.store_code_block(fixup.fixup_code(op.load_code_block()));
  98         }
  99 };
 100
 101 template<typename Fixup>
 102 void code_block_visitor<Fixup>::visit_embedded_code_pointers(code_block *compiled)
 103 {
 104         if(!parent->code->uninitialized_p(compiled))
 105         {
 106                 embedded_code_pointers_visitor<Fixup> operand_visitor(fixup);
 107                 compiled->each_instruction_operand(operand_visitor);
 108         }
 109 }
 110
 111 template<typename Fixup>
 112 void code_block_visitor<Fixup>::visit_context_code_blocks()
 113 {
 114         call_frame_code_block_visitor<Fixup> call_frame_visitor(parent,fixup);
 115         parent->iterate_active_callstacks(call_frame_visitor);
 116 }
 117
 118 template<typename Fixup>
 119 void code_block_visitor<Fixup>::visit_uninitialized_code_blocks()
 120 {
 121         std::map<code_block *, cell> *uninitialized_blocks = &parent->code->uninitialized_blocks;
 122         std::map<code_block *, cell>::const_iterator iter = uninitialized_blocks->begin();
 123         std::map<code_block *, cell>::const_iterator end = uninitialized_blocks->end();
 124
 125         std::map<code_block *, cell> new_uninitialized_blocks;
 126         for(; iter != end; iter++)
 127         {
 128                 new_uninitialized_blocks.insert(std::make_pair(
 129                         fixup.fixup_code(iter->first),
 130                         iter->second));
 131         }
 132
 133         parent->code->uninitialized_blocks = new_uninitialized_blocks;
 134 }
 135
 136 }