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<base href="https://llvm.org/bugs/" />
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<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Missing CFI directive after func epilogue and before ret"
href="https://llvm.org/bugs/show_bug.cgi?id=25916">25916</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Missing CFI directive after func epilogue and before ret
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>DebugInfo
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>wmi@google.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=15508" name="attach_15508" title="testcase">attachment 15508</a> <a href="attachment.cgi?id=15508&action=edit" title="testcase">[details]</a></span>
testcase
Using the most recent clang (r255910)
clang -fsanitize=address ill.cc
ASAN_OPTIONS=handle_sigill=1:fast_unwind_on_fatal=0 ./a.out
It will catch a SIGILL signal (correct behavior) and then catch SIGSEGV:
Program received signal SIGSEGV, Segmentation fault.
_Unwind_GetGR (index=16, context=0x7ffff7fe5ef0) at
../../../libgcc/unwind-dw2.c:244
244 ../../../libgcc/unwind-dw2.c: No such file or directory.
(gdb) bt
#0 _Unwind_GetGR (index=16, context=0x7ffff7fe5ef0) at
../../../libgcc/unwind-dw2.c:244
#1 _Unwind_GetPtr (index=16, context=0x7ffff7fe5ef0) at
../../../libgcc/unwind-dw2.c:255
#2 uw_update_context (context=context@entry=0x7ffff7fe5ef0,
fs=fs@entry=0x7ffff7fe5fe0) at ../../../libgcc/unwind-dw2.c:1523
#3 0x00007ffff72a3e3e in _Unwind_Backtrace (trace=0x4d14d0 <Unwind_Trace()>,
trace_argument=0x7ffff7fe61a0) at ../../../libgcc/unwind.inc:303
#4 0x00000000004d16ec in SlowUnwindStack
Assembly:
~/workarea/llvm-r255910/dbuild/bin/clang -fsanitize=address ill.cc -S
main: # @main
.cfi_startproc
# BB#0: # %entry
pushq %rbp
.Ltmp3:
.cfi_def_cfa_offset 16
.Ltmp4:
.cfi_offset %rbp, -16
movq %rsp, %rbp
.Ltmp5:
.cfi_def_cfa_register %rbp
subq $16, %rsp
movabsq $_Z5deathv, %rax
movl %edi, -4(%rbp)
movq %rsi, -16(%rbp)
movq %rax, %rdi
callq __sanitizer_set_death_callback
callq __asan_handle_no_return
xorl %eax, %eax
addq $16, %rsp
popq %rbp // After this instruction, cfa register should be
changed to rsp again. ".cfi_def_cfa 7, 8" should be inserted after the
instruction.
ud2
retq
.Lfunc_end1:
.size main, .Lfunc_end1-main
.cfi_endproc
If ".cfi_def_cfa 7, 8" is added before ud2 manually, the SEGV will be gone.</pre>
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