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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Throwing C++ exception after getting address of JITted function causes segfault."
href="https://bugs.llvm.org/show_bug.cgi?id=34424">34424</a>
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<th>Summary</th>
<td>Throwing C++ exception after getting address of JITted function causes segfault.
</td>
</tr>
<tr>
<th>Product</th>
<td>new-bugs
</td>
</tr>
<tr>
<th>Version</th>
<td>4.0
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>new bugs
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>samuelmarinelli@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
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<pre>Created <span class=""><a href="attachment.cgi?id=19078" name="attach_19078" title="Source file reproducing the bug.">attachment 19078</a> <a href="attachment.cgi?id=19078&action=edit" title="Source file reproducing the bug.">[details]</a></span>
Source file reproducing the bug.
I have a simple JIT implementation that JITs a function, gets its address,
calls it, and removes it from the JIT. After doing this, I find that any throw
of a C++ exception, caught or uncaught, causes a segfault.
The attached source file is a minimal example. In fact calling the JITted
function is unnecessary to produce the error; all that's necessary is to get
its address by calling llvm::JITSymbol::getAddress on the symbol produced by
llvm::orc::IRCompileLayer<llvm::orc::ObjectLinkingLayer<>>::findSymbol.
Removing the call to getAddress in line 88 produces a non-segfaulting
executable, as does removing the call to
IRCompileLayer<ObjectLinkingLayer<>>::removeModuleSet in line 90.
I compile the code using the following command.
g++ -g main.cc `llvm-config --cxxflags --ldflags --system-libs --libs \
core mcjit native` -O0 -o example -std=c++17 -Wall -Wextra \
-Wno-unused-function -Wno-unused-value -Wno-unused-parameter -Werror
I'm using LLVM 4.0.1 and GCC 7.1.1 on Arch Linux. I explicitly turned on
exception handling in LLVM during the build using -DLLVM_ENABLE_EH=ON, thinking
that the default --fno-exceptions flag passed to the compiler might to blame,
but no such luck.
Here's the backtrace from GDB.
Program received signal SIGSEGV, Segmentation fault.
classify_object_over_fdes (ob=0x101437c00,
this_fde=this_fde@entry=0x7fe5b0413000) at
/build/gcc/src/gcc/libgcc/unwind-dw2-fde.c:641
641 /build/gcc/src/gcc/libgcc/unwind-dw2-fde.c: No such file or directory.
(gdb) bt
#0 classify_object_over_fdes (ob=0x101437c00,
this_fde=this_fde@entry=0x7fe5b0413000) at
/build/gcc/src/gcc/libgcc/unwind-dw2-fde.c:641
#1 0x00007fe5aeeab7d8 in init_object (ob=0x101437c00) at
/build/gcc/src/gcc/libgcc/unwind-dw2-fde.c:777
#2 search_object (ob=ob@entry=0x101437c00, pc=pc@entry=0x7fe5aeeaa17d
<_Unwind_RaiseException+61>) at /build/gcc/src/gcc/libgcc/unwind-dw2-fde.c:989
#3 0x00007fe5aeeac666 in _Unwind_Find_registered_FDE (bases=0x7fffffffddc8,
pc=0x7fe5aeeaa17d <_Unwind_RaiseException+61>)
at /build/gcc/src/gcc/libgcc/unwind-dw2-fde.c:1066
#4 _Unwind_Find_FDE (pc=0x7fe5aeeaa17d <_Unwind_RaiseException+61>,
bases=bases@entry=0x7fffffffddc8) at
/build/gcc/src/gcc/libgcc/unwind-dw2-fde-dip.c:458
#5 0x00007fe5aeea8a73 in uw_frame_state_for
(context=context@entry=0x7fffffffdd20, fs=fs@entry=0x7fffffffdb70) at
/build/gcc/src/gcc/libgcc/unwind-dw2.c:1249
#6 0x00007fe5aeea9ce0 in uw_init_context_1
(context=context@entry=0x7fffffffdd20,
outer_cfa=outer_cfa@entry=0x7fffffffe0d0, outer_ra=
0x7fe5af452ec6 <__cxxabiv1::__cxa_throw(void*, std::type_info*, void
(*)(void*))+54>) at /build/gcc/src/gcc/libgcc/unwind-dw2.c:1578
#7 0x00007fe5aeeaa17e in _Unwind_RaiseException (exc=exc@entry=0x101426b10) at
/build/gcc/src/gcc/libgcc/unwind.inc:88
#8 0x00007fe5af452ec6 in __cxxabiv1::__cxa_throw (obj=<optimized out>,
tinfo=0x7fe5af73ea90 <typeinfo for std::runtime_error>,
dest=0x7fe5af468500 <std::runtime_error::~runtime_error()>) at
/build/gcc/src/gcc/libstdc++-v3/libsupc++/eh_throw.cc:88
#9 0x000000010012fa5e in main () at main.cc:94</pre>
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