rt.deh source code

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 module rt.deh;
37 
38 extern (C)
39 {
40     Throwable.TraceInfo _d_traceContext(void* ptr = null);
41     Throwable.TraceDeallocator rt_getTraceDeallocator();
42     void _d_createTrace(Throwable t, void* context)
43     {
44         if (t !is null && t.info is null &&
45             cast(byte*) t !is typeid(t).initializer.ptr)
46         {
47             t.info = _d_traceContext(context);
48             t.infoDeallocator = rt_getTraceDeallocator();
49         }
50     }
51 }
52 
53 version (Win32)
54     public import rt.deh_win32;
55 else version (Win64)
56     public import rt.deh_win64_posix;
57 else version (Posix)
58     public import rt.deh_win64_posix;
59 else
60     static assert (0, "Unsupported architecture");