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Add recognition for another x86 epilogue sequence (ret followed by 

a nop).  Fixes an instruction stepping problem when trying to step
over the final instructions of an epilogue.
<rdar://problem/18068877> 

llvm-svn: 221241
This commit is contained in:
Jason Molenda 2014-11-04 05:48:11 +00:00
parent 652a3f3257
commit 8030ffda91
1 changed files with 11 additions and 0 deletions
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11
lldb/source/Plugins/UnwindAssembly/x86/UnwindAssembly-x86.cpp
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@ -804,6 +804,12 @@ loopnext:
// [ 0xc3 ] ret
// [ 0xe8 xx xx xx xx ] call __stack_chk_fail (this is sometimes the final insn in the function)
// or
// [ 0x5d ] mov %rbp, %rsp (aka pop %rbp)
// [ 0xc3 ] ret
// [ 0x0f 0x1f 0x44 xx xx ] nopl (%rax,%rax) (aka nop)
// We want to add a Row describing how to unwind when we're stopped on the 'ret' instruction where the
// CFA is no longer defined in terms of rbp, but is now defined in terms of rsp like on function entry.
// (or the 'jmp' instruction in the second case)
@ -834,6 +840,11 @@ loopnext:
{
ret_insn_offset = m_func_bounds.GetByteSize() - 6;
}
else if (bytebuf[0] == 0x5d && bytebuf[1] == 0xc3
&& bytebuf[2] == 0x0f && bytebuf[3] == 0x1f & bytebuf[4] == 0x44) // mov & ret & nop
{
ret_insn_offset = m_func_bounds.GetByteSize() - 6;
}
}
}
else if (m_func_bounds.GetByteSize() > 2)