vm/jit.cpp

   1 #include "master.hpp"
   2
   3 namespace factor
   4 {
   5
   6 /* Simple code generator used by:
   7 - profiler (profiler.cpp),
   8 - quotation compiler (quotations.cpp),
   9 - megamorphic caches (dispatch.cpp),
  10 - polymorphic inline caches (inline_cache.cpp) */
  11
  12 /* Allocates memory */
  13 jit::jit(cell type_, cell owner_)
  14         : type(type_),
  15           owner(owner_),
  16           code(),
  17           relocation(),
  18           literals(),
  19           computing_offset_p(false),
  20           position(0),
  21           offset(0)
  22 {
  23         if(stack_traces_p()) literal(owner.value());
  24 }
  25
  26 void jit::emit_relocation(cell code_template_)
  27 {
  28         gc_root<array> code_template(code_template_);
  29         cell capacity = array_capacity(code_template.untagged());
  30         for(cell i = 1; i < capacity; i += 3)
  31         {
  32                 cell rel_class = array_nth(code_template.untagged(),i);
  33                 cell rel_type = array_nth(code_template.untagged(),i + 1);
  34                 cell offset = array_nth(code_template.untagged(),i + 2);
  35
  36                 relocation_entry new_entry
  37                         = (untag_fixnum(rel_type) << 28)
  38                         | (untag_fixnum(rel_class) << 24)
  39                         | ((code.count + untag_fixnum(offset)));
  40                 relocation.append_bytes(&new_entry,sizeof(relocation_entry));
  41         }
  42 }
  43
  44 /* Allocates memory */
  45 void jit::emit(cell code_template_)
  46 {
  47         gc_root<array> code_template(code_template_);
  48
  49         emit_relocation(code_template.value());
  50
  51         gc_root<byte_array> insns(array_nth(code_template.untagged(),0));
  52
  53         if(computing_offset_p)
  54         {
  55                 cell size = array_capacity(insns.untagged());
  56
  57                 if(offset == 0)
  58                 {
  59                         position--;
  60                         computing_offset_p = false;
  61                 }
  62                 else if(offset < size)
  63                 {
  64                         position++;
  65                         computing_offset_p = false;
  66                 }
  67                 else
  68                         offset -= size;
  69         }
  70
  71         code.append_byte_array(insns.value());
  72 }
  73
  74 void jit::emit_with(cell code_template_, cell argument_) {
  75         gc_root<array> code_template(code_template_);
  76         gc_root<object> argument(argument_);
  77         literal(argument.value());
  78         emit(code_template.value());
  79 }
  80
  81 void jit::emit_class_lookup(fixnum index, cell type)
  82 {
  83         emit_with(userenv[PIC_LOAD],tag_fixnum(-index * sizeof(cell)));
  84         emit(userenv[type]);
  85 }
  86
  87 /* Facility to convert compiled code offsets to quotation offsets.
  88 Call jit_compute_offset() with the compiled code offset, then emit
  89 code, and at the end jit->position is the quotation position. */
  90 void jit::compute_position(cell offset_)
  91 {
  92         computing_offset_p = true;
  93         position = 0;
  94         offset = offset_;
  95 }
  96
  97 /* Allocates memory */
  98 code_block *jit::to_code_block()
  99 {
 100         code.trim();
 101         relocation.trim();
 102         literals.trim();
 103
 104         return add_code_block(
 105                 type,
 106                 code.elements.value(),
 107                 F, /* no labels */
 108                 relocation.elements.value(),
 109                 literals.elements.value());
 110 }
 111
 112 }