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Revert one part of Ashok Thirumurthi's patch from September 16, r190812. 

In those set of patches, Ashok changed Module::ResolveSymbolContextForAddress 
so that if it failed to find a symbol for a pc, it could back up
the pc value by 1 and re-search for a symbol.

His change to RegisterContextLLDB.cpp partially duplicates that
behavior but it also removes the separate case where we find a
Symbol for the pc address but it's the wrong symbol -- we need to
handle this as well as the lookup-by-pc-finds-no-symbol case.

The most obvious fallout from this regression was that lldb on
Mac OS X couldn't backtrace past __assert_rtn() which tail-calls 
abort().  e.g.

(lldb) bt
* thread #1: tid = 0x5d6ea1, 0x00007fff8ee80866 libsystem_kernel.dylib`__pthread_kill + 10, queue = 'com.apple.main-thread', stop reason = signal SIGABRT
  * frame #0: 0x00007fff8ee80866 libsystem_kernel.dylib`__pthread_kill + 10
    frame #1: 0x00007fff8eb5835c libsystem_pthread.dylib`pthread_kill + 92
    frame #2: 0x00007fff8852ab1a libsystem_c.dylib`abort + 125
    frame #3: 0x00007fff884f49bf libsystem_c.dylib`__assert_rtn + 321
    frame #4: 0x0000000100000f2c a.out`main + 124

(lldb) dis -c 3 -s 0x7fff884f49b3
libsystem_c.dylib`__assert_rtn + 309:
   0x7fff884f49b3:  movq   %rax, -0x11b96242(%rip)   ; gCRAnnotations + 8
   0x7fff884f49ba:  callq  0x7fff8854fd2c            ; symbol stub for: abort

libsystem_c.dylib`basename:
   0x7fff884f49bf:  pushq  %rbp
(lldb) 

in this case, __assert_rtn() is immediately followed by basename() and 
the changes in r190812 didn't back up the pc value to get the correct
function name / unwind info.

<rdar://problem/15367233> 

llvm-svn: 197655
This commit is contained in:
Jason Molenda 2013-12-19 04:32:42 +00:00
parent ab918c4e8e
commit 91e428bc90
1 changed files with 23 additions and 6 deletions
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29
lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
View File

@ -393,18 +393,35 @@ RegisterContextLLDB::InitializeNonZerothFrame()
if (m_sym_ctx_valid == false)
decr_pc_and_recompute_addr_range = true;
// Or if we're in the middle of the stack (and not "above" an asynchronous event like sigtramp), and
// our "current" pc is the start of a function or our "current" pc is one past the end of a function...
// Or if we're in the middle of the stack (and not "above" an asynchronous event like sigtramp),
// and our "current" pc is the start of a function...
if (m_sym_ctx_valid
&& GetNextFrame()->m_frame_type != eSigtrampFrame
&& GetNextFrame()->m_frame_type != eDebuggerFrame
&& addr_range.GetBaseAddress().IsValid()
&& addr_range.GetBaseAddress().GetSection() == m_current_pc.GetSection())
&& addr_range.GetBaseAddress().GetSection() == m_current_pc.GetSection()
&& addr_range.GetBaseAddress().GetOffset() == m_current_pc.GetOffset())
{
if (addr_range.GetBaseAddress().GetOffset() == m_current_pc.GetOffset() ||
addr_range.GetBaseAddress().GetOffset() + addr_range.GetByteSize() == m_current_pc.GetOffset())
decr_pc_and_recompute_addr_range = true;
}
// We need to back up the pc by 1 byte and re-search for the Symbol to handle the case where the "saved pc"
// value is pointing to the next function, e.g. if a function ends with a CALL instruction.
// FIXME this may need to be an architectural-dependent behavior; if so we'll need to add a member function
// to the ABI plugin and consult that.
if (decr_pc_and_recompute_addr_range)
{
Address temporary_pc(m_current_pc);
temporary_pc.SetOffset(m_current_pc.GetOffset() - 1);
m_sym_ctx.Clear(false);
m_sym_ctx_valid = false;
if ((pc_module_sp->ResolveSymbolContextForAddress (temporary_pc, eSymbolContextFunction| eSymbolContextSymbol, m_sym_ctx) & eSymbolContextSymbol) == eSymbolContextSymbol)
{
decr_pc_and_recompute_addr_range = true;
m_sym_ctx_valid = true;
}
if (!m_sym_ctx.GetAddressRange (eSymbolContextFunction | eSymbolContextSymbol, 0, false, addr_range))
{
m_sym_ctx_valid = false;
}
}