[Issue 19086] Bad stack trace for exceptions

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=19086

Rainer Schuetze <r.sagitario at gmx.de> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |r.sagitario at gmx.de

--- Comment #2 from Rainer Schuetze <r.sagitario at gmx.de> ---
The difference of the call stacks printed by the program and shown in the
debugger are caused by "throw" capturing the stack before actually raising the
exception. This avoids having to walk a couple of optimized functions without a
standard stack frame.

The reason for sometimes no line number showing is that the return address for
the call to _d_throwc is actually outside of the function:

--- test.d ----
_Dmain:
00007FF703CF1080 55                   push        rbp  
...
00007FF703CF109F 48 83 EC 20          sub         rsp,20h  
00007FF703CF10A3 E8 D8 01 00 00       call        _d_throwc (07FF703CF1280h)  
--- No source file -------
00007FF703CF10A8 CC                   int         3  
00007FF703CF10A9 CC                   int         3  

If you add another function after main and main happens to have a size that is
a multiple of 16 bytes, the following function in the binary gets shown in the
call stack:

// moved here to keep main short
Exception newException() { return new Exception("hi"); }

void main()
{
    long x = 1;
    int y = 0;
    throw newException();
}

void foo()
{
}

compiled with dmd2.083 via "dmd -g -m64 test.d -L/INCREMENTAL:NO"

--- c:\tmp\d\ex\test.d -------
_Dmain:
00007FF79AFA1080 55                   push        rbp  
00007FF79AFA1081 48 8B EC             mov         rbp,rsp  
00007FF79AFA1084 48 83 EC 10          sub         rsp,10h  
00007FF79AFA1088 48 C7 45 F0 01 00 00 00 mov         qword ptr [x],1  
00007FF79AFA1090 C7 45 F8 00 00 00 00 mov         dword ptr [y],0  
00007FF79AFA1097 48 83 EC 20          sub         rsp,20h  
00007FF79AFA109B E8 60 FF FF FF       call        test.newException
(07FF79AFA1000h)  
00007FF79AFA10A0 48 83 C4 20          add         rsp,20h  
00007FF79AFA10A4 48 89 C1             mov         rcx,rax  
00007FF79AFA10A7 48 83 EC 20          sub         rsp,20h  
00007FF79AFA10AB E8 D0 01 00 00       call        _d_throwc (07FF79AFA1280h)  
_D4test3fooFZv:
00007FF79AFA10B0 55                   push        rbp  
00007FF79AFA10B1 48 8B EC             mov         rbp,rsp  
00007FF79AFA10B4 5D                   pop         rbp  
00007FF79AFA10B5 C3                   ret  

yields a pretty broken callstack in the debugger and also in the program
output:

object.Exception at test.d(6): hi
----------------
0x00007FF79AFA10B0 in void test.foo() at c:\tmp\d\ex\test.d(13)
0x000001943E261000

--