libphobos/libdruntime/rt/deh.d

   1 /**
   2  * Entry point for exception handling support routines.
   3  *
   4  * There are three style of exception handling being supported by DMD:
   5  * DWARF, Win32, and Win64. The Win64 code also supports POSIX.
   6  * Support for those scheme is in `rt.dwarfeh`, `rt.deh_win32`, and
   7  * `rt.deh_win64_posix`, respectively, and publicly imported here.
   8  *
   9  * When an exception is thrown by the user, the compiler translates
  10  * code like `throw e;` into either `_d_throwdwarf` (for DWARF exceptions)
  11  * or `_d_throwc` (Win32 / Win64), with the `Exception` object as argument.
  12  *
  13  * During those functions' handling, they eventually call `_d_createTrace`,
  14  * which will store inside the `Exception` object the return of
  15  * `_d_traceContext`, which is an object implementing  `Throwable.TraceInfo`.
  16  * `_d_traceContext` is a configurable hook, and by default will call
  17  * `core.runtime : defaultTraceHandler`, which itself will call `backtrace`
  18  * or something similar to store an array of stack frames (`void*` pointers)
  19  * in the object it returns.
  20  * Note that `defaultTraceHandler` returns a GC-allocated instance,
  21  * hence a GC allocation can happen in the middle of throwing an `Exception`.
  22  *
  23  * The `Throwable.TraceInfo`-implementing should not resolves function names,
  24  * file and line number until its `opApply` function is called, avoiding the
  25  * overhead of reading the debug infos until the user call `toString`.
  26  * If the user only calls `Throwable.message` (or use `Throwable.msg` directly),
  27  * only the overhead of `backtrace` will be paid, which is minimal enouh.
  28  *
  29  * Copyright: Copyright Digital Mars 1999 - 2020.
  30  * License: Distributed under the
  31  *      $(LINK2 http://www.boost.org/LICENSE_1_0.txt, Boost Software License 1.0).
  32  *    (See accompanying file LICENSE)
  33  * Authors:   Walter Bright
  34  * Source: $(DRUNTIMESRC rt/deh.d)
  35  */
  36
  37 /* NOTE: This file has been patched from the original DMD distribution to
  38  * work with the GDC compiler.
  39  */
  40 module rt.deh;
  41
  42 extern (C)
  43 {
  44     Throwable.TraceInfo _d_traceContext(void* ptr = null);
  45     void _d_createTrace(Throwable t, void* context)
  46     {
  47         if (t !is null && t.info is null &&
  48             cast(byte*) t !is typeid(t).initializer.ptr)
  49         {
  50             t.info = _d_traceContext(context);
  51         }
  52     }
  53 }
  54
  55 version (GNU)
  56     public import gcc.deh;
  57 else version (Win32)
  58     public import rt.deh_win32;
  59 else version (Win64)
  60     public import rt.deh_win64_posix;
  61 else version (Posix)
  62     public import rt.deh_win64_posix;
  63 else
  64     static assert (0, "Unsupported architecture");