libphobos/libdruntime/rt/ehalloc.d

   1 /**
   2  * Exception allocation, cloning, and release compiler support routines.
   3  *
   4  * Copyright: Copyright (c) 2017 by D Language Foundation
   5  * License: Distributed under the
   6  *      $(LINK2 http://www.boost.org/LICENSE_1_0.txt, Boost Software License 1.0).
   7  *    (See accompanying file LICENSE)
   8  * Authors: Walter Bright
   9  * Source: $(DRUNTIMESRC rt/_ehalloc.d)
  10  */
  11
  12 module rt.ehalloc;
  13
  14 //debug = PRINTF;
  15
  16 debug(PRINTF)
  17 {
  18     import core.stdc.stdio;
  19 }
  20
  21
  22 /********************************************
  23  * Delete exception instance `t` from the exception pool.
  24  * Must have been allocated with `_d_newThrowable()`.
  25  * This is meant to be called at the close of a catch block.
  26  * It's nothrow because otherwise any function with a catch block could
  27  * not be nothrow.
  28  * Input:
  29  *      t = Throwable
  30  */
  31
  32 nothrow extern (C) void _d_delThrowable(Throwable t)
  33 {
  34     if (t)
  35     {
  36         debug(PRINTF) printf("_d_delThrowable(%p)\n", t);
  37
  38         /* If allocated by the GC, don't free it.
  39          * Let the GC handle it.
  40          * Supporting this is necessary while transitioning
  41          * to this new scheme for allocating exceptions.
  42          */
  43         auto refcount = t.refcount();
  44         if (refcount == 0)
  45             return;     // it was allocated by the GC
  46
  47         if (refcount == 1)
  48             assert(0);  // no zombie objects
  49
  50         t.refcount() = --refcount;
  51         if (refcount > 1)
  52             return;
  53
  54         TypeInfo_Class **pc = cast(TypeInfo_Class **)t;
  55         if (*pc)
  56         {
  57             TypeInfo_Class ci = **pc;
  58
  59             if (!(ci.m_flags & TypeInfo_Class.ClassFlags.noPointers))
  60             {
  61                 // Inform the GC about the pointers in the object instance
  62                 import core.memory : GC;
  63                 GC.removeRange(cast(void*) t);
  64             }
  65         }
  66
  67         try
  68         {
  69             import rt.lifetime : rt_finalize;
  70             rt_finalize(cast(void*) t);
  71         }
  72         catch (Throwable t)
  73         {
  74             assert(0);  // should never happen since Throwable.~this() is nothrow
  75         }
  76         import core.stdc.stdlib : free;
  77         debug(PRINTF) printf("free(%p)\n", t);
  78         free(cast(void*) t);
  79     }
  80 }