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digitalmars.D.bugs - [Issue 9025] New: core.thread.Fiber seems to crash on Win64

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=9025

           Summary: core.thread.Fiber seems to crash on Win64
           Product: D
           Version: D2
          Platform: x86_64
        OS/Version: Windows
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Phobos
        AssignedTo: nobody puremagic.com
        ReportedBy: turkeyman gmail.com


--- Comment #0 from Manu <turkeyman gmail.com> 2012-11-14 09:19:15 PST ---
It seems core.thread.Fiber doesn't work under the new DMD for win64.
Crashes on call(), in fiber_switchcontext(), access violation, looks like an
alignment problem, since the pointer is valid.


fiber_switchContext:
000007FEE25509E0  push        rbp  
000007FEE25509E1  mov         rbp,rsp  
000007FEE25509E4  push        rbx  
000007FEE25509E5  push        r12  
000007FEE25509E7  push        r13  
000007FEE25509E9  push        r14  
000007FEE25509EB  push        r15  
000007FEE25509ED  push        qword ptr gs:[fiber_switchContext+15h
(7FEE25509F5h)]  *** CRASH*** +15h? does 'push qword' support reading from
unaligned addresses like that?
000007FEE25509F5  push        qword ptr gs:[fiber_switchContext+25h
(7FEE2550A05h)]  
000007FEE25509FD  push        qword ptr gs:[fiber_switchContext+35h
(7FEE2550A15h)]  
000007FEE2550A05  mov         qword ptr [rdi],rsp  
000007FEE2550A08  mov         rsp,rsi  
000007FEE2550A0B  pop         qword ptr gs:[fiber_switchContext+43h
(7FEE2550A23h)]  
000007FEE2550A13  pop         qword ptr gs:[fiber_switchContext+43h
(7FEE2550A23h)]  
000007FEE2550A1B  pop         qword ptr gs:[fiber_switchContext+43h
(7FEE2550A23h)]  
000007FEE2550A23  pop         r15  
000007FEE2550A25  pop         r14  
000007FEE2550A27  pop         r13  
000007FEE2550A29  pop         r12  
000007FEE2550A2B  pop         rbx  
000007FEE2550A2C  pop         rbp  
000007FEE2550A2D  pop         rcx  
000007FEE2550A2E  jmp         rcx

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next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=9025


Walter Bright <bugzilla digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bugzilla digitalmars.com


--- Comment #1 from Walter Bright <bugzilla digitalmars.com> 2012-11-14
13:56:02 PST ---
qword means 4 bytes, and you can't push 4 bytes in 64 bit mode. Only 8 bytes.

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--- Comment #2 from Walter Bright <bugzilla digitalmars.com> 2012-11-15
00:01:38 PST ---
(In reply to comment #1)

 qword means 4 bytes, and you can't push 4 bytes in 64 bit mode. Only 8 bytes.


Aggh, that's wrong.

The source code is in src/core/thread.d, and looks like:


----------------------------------------------
                // save current stack state
                push RBP;
                mov  RBP, RSP;
                push RBX;
                push R12;
                push R13;
                push R14;
                push R15;
                push qword ptr GS:[0];
                push qword ptr GS:[8];
                push qword ptr GS:[16];

                // store oldp
                mov [RDI], RSP;
                // load newp to begin context switch
                mov RSP, RSI;

                // load saved state from new stack
                pop qword ptr GS:[16];
                pop qword ptr GS:[8];
                pop qword ptr GS:[0];
                pop R15;
                pop R14;
                pop R13;
                pop R12;
                pop RBX;
                pop RBP;

                // 'return' to complete switch
                pop RCX;
                jmp RCX;
----------------------------------------
So, if you could disassemble the code, it should be GS:[0], but I suspect the
assembler made it an offset from the program counter.

To fix,
                 xor RAX,RAX
                 push qword ptr GS:[RAX]
                 push qwork ptr GS:8[RAX]
                 ... etc. ...

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--- Comment #3 from Walter Bright <bugzilla digitalmars.com> 2012-11-15
00:03:49 PST ---
Confirmed, the [RIP] addressing mode is the problem.

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--- Comment #4 from github-bugzilla puremagic.com 2012-11-15 00:42:35 PST ---
Commit pushed to master at https://github.com/D-Programming-Language/druntime

https://github.com/D-Programming-Language/druntime/commit/b524769a1e3385dea96b2271ac14969d537db5c7
fix Issue 9025 - core.thread.Fiber seems to crash on Win64

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prev sibling parent d-bugmail puremagic.com writes:
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Walter Bright <bugzilla digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED


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