libgo/runtime/mgc0.h

   1 // Copyright 2012 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // Garbage collector (GC)
   6
   7 // GC instruction opcodes.
   8 //
   9 // The opcode of an instruction is followed by zero or more
  10 // arguments to the instruction.
  11 //
  12 // Meaning of arguments:
  13 //   off      Offset (in bytes) from the start of the current object
  14 //   objgc    Pointer to GC info of an object
  15 //   objgcrel Offset to GC info of an object
  16 //   len      Length of an array
  17 //   elemsize Size (in bytes) of an element
  18 //   size     Size (in bytes)
  19 //
  20 // NOTE: There is a copy of these in ../reflect/type.go.
  21 // They must be kept in sync.
  22 enum {
  23         GC_END,         // End of object, loop or subroutine. Args: none
  24         GC_PTR,         // A typed pointer. Args: (off, objgc)
  25         GC_APTR,        // Pointer to an arbitrary object. Args: (off)
  26         GC_ARRAY_START, // Start an array with a fixed length. Args: (off, len, elemsize)
  27         GC_ARRAY_NEXT,  // The next element of an array. Args: none
  28         GC_CALL,        // Call a subroutine. Args: (off, objgcrel)
  29         GC_CHAN_PTR,    // Go channel. Args: (off, ChanType*)
  30         GC_STRING,      // Go string. Args: (off)
  31         GC_EFACE,       // interface{}. Args: (off)
  32         GC_IFACE,       // interface{...}. Args: (off)
  33         GC_SLICE,       // Go slice. Args: (off, objgc)
  34         GC_REGION,      // A region/part of the current object. Args: (off, size, objgc)
  35
  36         GC_NUM_INSTR,   // Number of instruction opcodes
  37 };
  38
  39 enum {
  40         // Size of GC's fixed stack.
  41         //
  42         // The current GC implementation permits:
  43         //  - at most 1 stack allocation because of GC_CALL
  44         //  - at most GC_STACK_CAPACITY allocations because of GC_ARRAY_START
  45         GC_STACK_CAPACITY = 8,
  46 };