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  * Allocate an exception of type `ci` from the exception pool.
  23  * It has the same interface as `rt.lifetime._d_newclass()`.
  24  * The class type must be Throwable or derived from it,
  25  * and cannot be a COM or C++ class. The compiler must enforce
  26  * this.
  27  * Returns:
  28  *      default initialized instance of the type
  29  */
  30
  31 extern (C) Throwable _d_newThrowable(const TypeInfo_Class ci)
  32 {
  33     debug(PRINTF) printf("_d_newThrowable(ci = %p, %s)\n", ci, cast(char *)ci.name);
  34
  35     assert(!(ci.m_flags & TypeInfo_Class.ClassFlags.isCOMclass));
  36     assert(!(ci.m_flags & TypeInfo_Class.ClassFlags.isCPPclass));
  37
  38     import core.stdc.stdlib : malloc;
  39     auto init = ci.initializer;
  40     void* p = malloc(init.length);
  41     if (!p)
  42     {
  43         import core.exception : onOutOfMemoryError;
  44         onOutOfMemoryError();
  45     }
  46
  47     debug(PRINTF) printf(" p = %p\n", p);
  48
  49     // initialize it
  50     p[0 .. init.length] = init[];
  51
  52     if (!(ci.m_flags & TypeInfo_Class.ClassFlags.noPointers))
  53     {
  54         // Inform the GC about the pointers in the object instance
  55         import core.memory : GC;
  56
  57         GC.addRange(p, init.length, ci);
  58     }
  59
  60     debug(PRINTF) printf("initialization done\n");
  61     Throwable t = cast(Throwable)p;
  62     t.refcount() = 1;
  63     return t;
  64 }
  65
  66
  67 /********************************************
  68  * Delete exception instance `t` from the exception pool.
  69  * Must have been allocated with `_d_newThrowable()`.
  70  * This is meant to be called at the close of a catch block.
  71  * It's nothrow because otherwise any function with a catch block could
  72  * not be nothrow.
  73  * Input:
  74  *      t = Throwable
  75  */
  76
  77 nothrow extern (C) void _d_delThrowable(Throwable t)
  78 {
  79     if (t)
  80     {
  81         debug(PRINTF) printf("_d_delThrowable(%p)\n", t);
  82
  83         /* If allocated by the GC, don't free it.
  84          * Let the GC handle it.
  85          * Supporting this is necessary while transitioning
  86          * to this new scheme for allocating exceptions.
  87          */
  88         auto refcount = t.refcount();
  89         if (refcount == 0)
  90             return;     // it was allocated by the GC
  91
  92         if (refcount == 1)
  93             assert(0);  // no zombie objects
  94
  95         t.refcount() = --refcount;
  96         if (refcount > 1)
  97             return;
  98
  99         TypeInfo_Class **pc = cast(TypeInfo_Class **)t;
 100         if (*pc)
 101         {
 102             TypeInfo_Class ci = **pc;
 103
 104             if (!(ci.m_flags & TypeInfo_Class.ClassFlags.noPointers))
 105             {
 106                 // Inform the GC about the pointers in the object instance
 107                 import core.memory : GC;
 108                 GC.removeRange(cast(void*) t);
 109             }
 110         }
 111
 112         try
 113         {
 114             import rt.lifetime : rt_finalize;
 115             rt_finalize(cast(void*) t);
 116         }
 117         catch (Throwable t)
 118         {
 119             assert(0);  // should never happen since Throwable.~this() is nothrow
 120         }
 121         import core.stdc.stdlib : free;
 122         debug(PRINTF) printf("free(%p)\n", t);
 123         free(cast(void*) t);
 124     }
 125 }