Add libc++ and libc++abi to third-party.

third_party/libc++abi/src/cxa_personality.cpp

+//===------------------------- cxa_exception.cpp --------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//  
+//  This file implements the "Exception Handling APIs"
+//  http://www.codesourcery.com/public/cxx-abi/abi-eh.html
+//  http://www.intel.com/design/itanium/downloads/245358.htm
+//  
+//===----------------------------------------------------------------------===//
+
+#include "unwind.h"
+#include "cxa_exception.hpp"
+#include "cxa_handlers.hpp"
+#include "private_typeinfo.h"
+#include <typeinfo>
+#include <stdlib.h>
+#include <assert.h>
+
+/*
+    Exception Header Layout:
+
++---------------------------+-----------------------------+---------------+
+| __cxa_exception           | _Unwind_Exception CLNGC++\0 | thrown object |
++---------------------------+-----------------------------+---------------+
+                                                          ^
+                                                          |
+  +-------------------------------------------------------+
+  |
++---------------------------+-----------------------------+
+| __cxa_dependent_exception | _Unwind_Exception CLNGC++\1 |
++---------------------------+-----------------------------+
+
+    Exception Handling Table Layout:
+
++-----------------+--------+
+| lpStartEncoding | (char) |
++---------+-------+--------+---------------+-----------------------+
+| lpStart | (encoded with lpStartEncoding) | defaults to funcStart |
++---------+-----+--------+-----------------+---------------+-------+
+| ttypeEncoding | (char) | Encoding of the type_info table |
++---------------+-+------+----+----------------------------+----------------+
+| classInfoOffset | (ULEB128) | Offset to type_info table, defaults to null |
++-----------------++--------+-+----------------------------+----------------+
+| callSiteEncoding | (char) | Encoding for Call Site Table |
++------------------+--+-----+-----+------------------------+--------------------------+
+| callSiteTableLength | (ULEB128) | Call Site Table length, used to find Action table |
++---------------------+-----------+---------------------------------------------------+
+#if !__arm__
++---------------------+-----------+------------------------------------------------+
+| Beginning of Call Site Table            The current ip lies within the           |
+| ...                                     (start, length) range of one of these    |
+|                                         call sites. There may be action needed.  |
+| +-------------+---------------------------------+------------------------------+ |
+| | start       | (encoded with callSiteEncoding) | offset relative to funcStart | |
+| | length      | (encoded with callSiteEncoding) | length of code fragment      | |
+| | landingPad  | (encoded with callSiteEncoding) | offset relative to lpStart   | |
+| | actionEntry | (ULEB128)                       | Action Table Index 1-based   | |
+| |             |                                 | actionEntry == 0 -> cleanup  | |
+| +-------------+---------------------------------+------------------------------+ |
+| ...                                                                              |
++----------------------------------------------------------------------------------+
+#else  // __arm_
++---------------------+-----------+------------------------------------------------+
+| Beginning of Call Site Table            The current ip is a 1-based index into   |
+| ...                                     this table.  Or it is -1 meaning no      |
+|                                         action is needed.  Or it is 0 meaning    |
+|                                         terminate.                               |
+| +-------------+---------------------------------+------------------------------+ |
+| | landingPad  | (ULEB128)                       | offset relative to lpStart   | |
+| | actionEntry | (ULEB128)                       | Action Table Index 1-based   | |
+| |             |                                 | actionEntry == 0 -> cleanup  | |
+| +-------------+---------------------------------+------------------------------+ |
+| ...                                                                              |
++----------------------------------------------------------------------------------+
+#endif  // __arm_
++---------------------------------------------------------------------+
+| Beginning of Action Table       ttypeIndex == 0 : cleanup           |
+| ...                             ttypeIndex  > 0 : catch             |
+|                                 ttypeIndex  < 0 : exception spec    |
+| +--------------+-----------+--------------------------------------+ |
+| | ttypeIndex   | (SLEB128) | Index into type_info Table (1-based) | |
+| | actionOffset | (SLEB128) | Offset into next Action Table entry  | |
+| +--------------+-----------+--------------------------------------+ |
+| ...                                                                 |
++---------------------------------------------------------------------+-----------------+
+| type_info Table, but classInfoOffset does *not* point here!                           |
+| +----------------+------------------------------------------------+-----------------+ |
+| | Nth type_info* | Encoded with ttypeEncoding, 0 means catch(...) | ttypeIndex == N | |
+| +----------------+------------------------------------------------+-----------------+ |
+| ...                                                                                   |
+| +----------------+------------------------------------------------+-----------------+ |
+| | 1st type_info* | Encoded with ttypeEncoding, 0 means catch(...) | ttypeIndex == 1 | |
+| +----------------+------------------------------------------------+-----------------+ |
+| +---------------------------------------+-----------+------------------------------+  |
+| | 1st ttypeIndex for 1st exception spec | (ULEB128) | classInfoOffset points here! |  |
+| | ...                                   | (ULEB128) |                              |  |
+| | Mth ttypeIndex for 1st exception spec | (ULEB128) |                              |  |
+| | 0                                     | (ULEB128) |                              |  |
+| +---------------------------------------+------------------------------------------+  |
+| ...                                                                                   |
+| +---------------------------------------+------------------------------------------+  |
+| | 0                                     | (ULEB128) | throw()                      |  |
+| +---------------------------------------+------------------------------------------+  |
+| ...                                                                                   |
+| +---------------------------------------+------------------------------------------+  |
+| | 1st ttypeIndex for Nth exception spec | (ULEB128) |                              |  |
+| | ...                                   | (ULEB128) |                              |  |
+| | Mth ttypeIndex for Nth exception spec | (ULEB128) |                              |  |
+| | 0                                     | (ULEB128) |                              |  |
+| +---------------------------------------+------------------------------------------+  |
++---------------------------------------------------------------------------------------+
+
+Notes:
+
+*  ttypeIndex in the Action Table, and in the exception spec table, is an index,
+     not a byte count, if positive.  It is a negative index offset of
+     classInfoOffset and the sizeof entry depends on ttypeEncoding.
+   But if ttypeIndex is negative, it is a positive 1-based byte offset into the
+     type_info Table.
+   And if ttypeIndex is zero, it refers to a catch (...).
+
+*  landingPad can be 0, this implies there is nothing to be done.
+
+*  landingPad != 0 and actionEntry == 0 implies a cleanup needs to be done
+     @landingPad.
+
+*  A cleanup can also be found under landingPad != 0 and actionEntry != 0 in
+     the Action Table with ttypeIndex == 0.
+*/
+
+namespace __cxxabiv1
+{
+
+extern "C"
+{
+
+// private API
+
+// Heavily borrowed from llvm/examples/ExceptionDemo/ExceptionDemo.cpp
+
+// DWARF Constants
+enum
+{
+    DW_EH_PE_absptr   = 0x00,
+    DW_EH_PE_uleb128  = 0x01,
+    DW_EH_PE_udata2   = 0x02,
+    DW_EH_PE_udata4   = 0x03,
+    DW_EH_PE_udata8   = 0x04,
+    DW_EH_PE_sleb128  = 0x09,
+    DW_EH_PE_sdata2   = 0x0A,
+    DW_EH_PE_sdata4   = 0x0B,
+    DW_EH_PE_sdata8   = 0x0C,
+    DW_EH_PE_pcrel    = 0x10,
+    DW_EH_PE_textrel  = 0x20,
+    DW_EH_PE_datarel  = 0x30,
+    DW_EH_PE_funcrel  = 0x40,
+    DW_EH_PE_aligned  = 0x50,
+    DW_EH_PE_indirect = 0x80,
+    DW_EH_PE_omit     = 0xFF
+};
+
+/// Read a uleb128 encoded value and advance pointer 
+/// See Variable Length Data Appendix C in: 
+/// @link http://dwarfstd.org/Dwarf4.pdf @unlink
+/// @param data reference variable holding memory pointer to decode from
+/// @returns decoded value
+static
+uintptr_t
+readULEB128(const uint8_t** data)
+{
+    uintptr_t result = 0;
+    uintptr_t shift = 0;
+    unsigned char byte;
+    const uint8_t *p = *data;
+    do
+    {
+        byte = *p++;
+        result |= static_cast<uintptr_t>(byte & 0x7F) << shift;
+        shift += 7;
+    } while (byte & 0x80);
+    *data = p;
+    return result;
+}
+
+/// Read a sleb128 encoded value and advance pointer 
+/// See Variable Length Data Appendix C in: 
+/// @link http://dwarfstd.org/Dwarf4.pdf @unlink
+/// @param data reference variable holding memory pointer to decode from
+/// @returns decoded value
+static
+intptr_t
+readSLEB128(const uint8_t** data)
+{
+    uintptr_t result = 0;
+    uintptr_t shift = 0;
+    unsigned char byte;
+    const uint8_t *p = *data;
+    do
+    {
+        byte = *p++;
+        result |= static_cast<uintptr_t>(byte & 0x7F) << shift;
+        shift += 7;
+    } while (byte & 0x80);
+    *data = p;
+    if ((byte & 0x40) && (shift < (sizeof(result) << 3)))
+        result |= static_cast<uintptr_t>(~0) << shift;
+    return static_cast<intptr_t>(result);
+}
+
+/// Read a pointer encoded value and advance pointer 
+/// See Variable Length Data in: 
+/// @link http://dwarfstd.org/Dwarf3.pdf @unlink
+/// @param data reference variable holding memory pointer to decode from
+/// @param encoding dwarf encoding type
+/// @returns decoded value
+static
+uintptr_t
+readEncodedPointer(const uint8_t** data, uint8_t encoding)
+{
+    uintptr_t result = 0;
+    if (encoding == DW_EH_PE_omit) 
+        return result;
+    const uint8_t* p = *data;
+    // first get value 
+    switch (encoding & 0x0F)
+    {
+    case DW_EH_PE_absptr:
+        result = *((uintptr_t*)p);
+        p += sizeof(uintptr_t);
+        break;
+    case DW_EH_PE_uleb128:
+        result = readULEB128(&p);
+        break;
+    case DW_EH_PE_sleb128:
+        result = static_cast<uintptr_t>(readSLEB128(&p));
+        break;
+    case DW_EH_PE_udata2:
+        result = *((uint16_t*)p);
+        p += sizeof(uint16_t);
+        break;
+    case DW_EH_PE_udata4:
+        result = *((uint32_t*)p);
+        p += sizeof(uint32_t);
+        break;
+    case DW_EH_PE_udata8:
+        result = static_cast<uintptr_t>(*((uint64_t*)p));
+        p += sizeof(uint64_t);
+        break;
+    case DW_EH_PE_sdata2:
+        result = static_cast<uintptr_t>(*((int16_t*)p));
+        p += sizeof(int16_t);
+        break;
+    case DW_EH_PE_sdata4:
+        result = static_cast<uintptr_t>(*((int32_t*)p));
+        p += sizeof(int32_t);
+        break;
+    case DW_EH_PE_sdata8:
+        result = static_cast<uintptr_t>(*((int64_t*)p));
+        p += sizeof(int64_t);
+        break;
+    default:
+        // not supported 
+        abort();
+        break;
+    }
+    // then add relative offset 
+    switch (encoding & 0x70)
+    {
+    case DW_EH_PE_absptr:
+        // do nothing 
+        break;
+    case DW_EH_PE_pcrel:
+        if (result)
+            result += (uintptr_t)(*data);
+        break;
+    case DW_EH_PE_textrel:
+    case DW_EH_PE_datarel:
+    case DW_EH_PE_funcrel:
+    case DW_EH_PE_aligned:
+    default:
+        // not supported 
+        abort();
+        break;
+    }
+    // then apply indirection 
+    if (result && (encoding & DW_EH_PE_indirect))
+        result = *((uintptr_t*)result);
+    *data = p;
+    return result;
+}
+
+static
+void
+call_terminate(bool native_exception, _Unwind_Exception* unwind_exception)
+{
+    __cxa_begin_catch(unwind_exception);
+    if (native_exception)
+    {
+        // Use the stored terminate_handler if possible
+        __cxa_exception* exception_header = (__cxa_exception*)(unwind_exception+1) - 1;
+        std::__terminate(exception_header->terminateHandler);
+    }
+    std::terminate();
+}
+
+static
+const __shim_type_info*
+get_shim_type_info(uint64_t ttypeIndex, const uint8_t* classInfo,
+                   uint8_t ttypeEncoding, bool native_exception,
+                   _Unwind_Exception* unwind_exception)
+{
+    if (classInfo == 0)
+    {
+        // this should not happen.  Indicates corrupted eh_table.
+        call_terminate(native_exception, unwind_exception);
+    }
+    switch (ttypeEncoding & 0x0F)
+    {
+    case DW_EH_PE_absptr:
+        ttypeIndex *= sizeof(void*);
+        break;
+    case DW_EH_PE_udata2:
+    case DW_EH_PE_sdata2:
+        ttypeIndex *= 2;
+        break;
+    case DW_EH_PE_udata4:
+    case DW_EH_PE_sdata4:
+        ttypeIndex *= 4;
+        break;
+    case DW_EH_PE_udata8:
+    case DW_EH_PE_sdata8:
+        ttypeIndex *= 8;
+        break;
+    default:
+        // this should not happen.   Indicates corrupted eh_table.
+        call_terminate(native_exception, unwind_exception);
+    }
+    classInfo -= ttypeIndex;
+    return (const __shim_type_info*)readEncodedPointer(&classInfo, ttypeEncoding);
+}
+
+/*
+    This is checking a thrown exception type, excpType, against a possibly empty
+    list of catchType's which make up an exception spec.
+
+    An exception spec acts like a catch handler, but in reverse.  This "catch
+    handler" will catch an excpType if and only if none of the catchType's in
+    the list will catch a excpType.  If any catchType in the list can catch an
+    excpType, then this exception spec does not catch the excpType.
+*/
+static
+bool
+exception_spec_can_catch(int64_t specIndex, const uint8_t* classInfo,
+                         uint8_t ttypeEncoding, const __shim_type_info* excpType,
+                         void* adjustedPtr, _Unwind_Exception* unwind_exception)
+{
+    if (classInfo == 0)
+    {
+        // this should not happen.   Indicates corrupted eh_table.
+        call_terminate(false, unwind_exception);
+    }
+    // specIndex is negative of 1-based byte offset into classInfo;
+    specIndex = -specIndex;
+    --specIndex;
+    const uint8_t* temp = classInfo + specIndex;
+    // If any type in the spec list can catch excpType, return false, else return true
+    //    adjustments to adjustedPtr are ignored.
+    while (true)
+    {
+        uint64_t ttypeIndex = readULEB128(&temp);
+        if (ttypeIndex == 0)
+            break;
+        const __shim_type_info* catchType = get_shim_type_info(ttypeIndex,
+                                                               classInfo,
+                                                               ttypeEncoding,
+                                                               true,
+                                                               unwind_exception);
+        void* tempPtr = adjustedPtr;
+        if (catchType->can_catch(excpType, tempPtr))
+            return false;
+    }
+    return true;
+}
+
+static
+void*
+get_thrown_object_ptr(_Unwind_Exception* unwind_exception)
+{
+    // Even for foreign exceptions, the exception object is *probably* at unwind_exception + 1
+    //    Regardless, this library is prohibited from touching a foreign exception
+    void* adjustedPtr = unwind_exception + 1;
+    if (unwind_exception->exception_class == kOurDependentExceptionClass)
+        adjustedPtr = ((__cxa_dependent_exception*)adjustedPtr - 1)->primaryException;
+    return adjustedPtr;
+}
+
+namespace
+{
+
+struct scan_results
+{
+    int64_t        ttypeIndex;   // > 0 catch handler, < 0 exception spec handler, == 0 a cleanup
+    const uint8_t* actionRecord;         // Currently unused.  Retained to ease future maintenance.
+    const uint8_t* languageSpecificData;  // Needed only for __cxa_call_unexpected
+    uintptr_t      landingPad;   // null -> nothing found, else something found
+    void*          adjustedPtr;  // Used in cxa_exception.cpp
+    _Unwind_Reason_Code reason;  // One of _URC_FATAL_PHASE1_ERROR,
+                                 //        _URC_FATAL_PHASE2_ERROR,
+                                 //        _URC_CONTINUE_UNWIND,
+                                 //        _URC_HANDLER_FOUND
+};
+
+}  // unnamed namespace
+
+static
+void
+set_registers(_Unwind_Exception* unwind_exception, _Unwind_Context* context,
+              const scan_results& results)
+{
+#if __arm__
+    _Unwind_SetGR(context, 0, reinterpret_cast<uintptr_t>(unwind_exception));
+    _Unwind_SetGR(context, 1, static_cast<uintptr_t>(results.ttypeIndex));
+#else
+    _Unwind_SetGR(context, __builtin_eh_return_data_regno(0),
+                                 reinterpret_cast<uintptr_t>(unwind_exception));
+    _Unwind_SetGR(context, __builtin_eh_return_data_regno(1),
+                                    static_cast<uintptr_t>(results.ttypeIndex));
+#endif
+    _Unwind_SetIP(context, results.landingPad);
+}
+
+/*
+    There are 3 types of scans needed:
+
+    1.  Scan for handler with native or foreign exception.  If handler found,
+        save state and return _URC_HANDLER_FOUND, else return _URC_CONTINUE_UNWIND.
+        May also report an error on invalid input.
+        May terminate for invalid exception table.
+        _UA_SEARCH_PHASE
+
+    2.  Scan for handler with foreign exception.  Must return _URC_HANDLER_FOUND,
+        or call terminate.
+        _UA_CLEANUP_PHASE && _UA_HANDLER_FRAME && !native_exception
+
+    3.  Scan for cleanups.  If a handler is found and this isn't forced unwind,
+        then terminate, otherwise ignore the handler and keep looking for cleanup.
+        If a cleanup is found, return _URC_HANDLER_FOUND, else return _URC_CONTINUE_UNWIND.
+        May also report an error on invalid input.
+        May terminate for invalid exception table.
+        _UA_CLEANUP_PHASE && !_UA_HANDLER_FRAME
+*/
+
+static
+void
+scan_eh_tab(scan_results& results, _Unwind_Action actions, bool native_exception,
+            _Unwind_Exception* unwind_exception, _Unwind_Context* context)
+{
+    // Initialize results to found nothing but an error
+    results.ttypeIndex = 0;
+    results.actionRecord = 0;
+    results.languageSpecificData = 0;
+    results.landingPad = 0;
+    results.adjustedPtr = 0;
+    results.reason = _URC_FATAL_PHASE1_ERROR;
+    // Check for consistent actions
+    if (actions & _UA_SEARCH_PHASE)
+    {
+        // Do Phase 1
+        if (actions & (_UA_CLEANUP_PHASE | _UA_HANDLER_FRAME | _UA_FORCE_UNWIND))
+        {
+            // None of these flags should be set during Phase 1
+            //   Client error
+            results.reason = _URC_FATAL_PHASE1_ERROR;
+            return;
+        }
+    }
+    else if (actions & _UA_CLEANUP_PHASE)
+    {
+        if ((actions & _UA_HANDLER_FRAME) && (actions & _UA_FORCE_UNWIND))
+        {
+            // _UA_HANDLER_FRAME should only be set if phase 1 found a handler.
+            // If _UA_FORCE_UNWIND is set, phase 1 shouldn't have happened.
+            //    Client error
+            results.reason = _URC_FATAL_PHASE2_ERROR;
+            return;
+        }
+    }
+    else // Neither _UA_SEARCH_PHASE nor _UA_CLEANUP_PHASE is set
+    {
+        // One of these should be set.
+        //   Client error
+        results.reason = _URC_FATAL_PHASE1_ERROR;
+        return;
+    }
+    // Start scan by getting exception table address
+    const uint8_t* lsda = (const uint8_t*)_Unwind_GetLanguageSpecificData(context);
+    if (lsda == 0)
+    {
+        // There is no exception table
+        results.reason = _URC_CONTINUE_UNWIND;
+        return;
+    }
+    results.languageSpecificData = lsda;
+    // Get the current instruction pointer and offset it before next
+    // instruction in the current frame which threw the exception.
+    uintptr_t ip = _Unwind_GetIP(context) - 1;
+    // Get beginning current frame's code (as defined by the 
+    // emitted dwarf code)
+    uintptr_t funcStart = _Unwind_GetRegionStart(context);
+#if __arm__
+    if (ip == uintptr_t(-1))
+    {
+        // no action
+        results.reason = _URC_CONTINUE_UNWIND;
+        return;
+    }
+    else if (ip == 0)
+        call_terminate(native_exception, unwind_exception);
+    // ip is 1-based index into call site table
+#else  // __arm__
+    uintptr_t ipOffset = ip - funcStart;
+#endif  // __arm__
+    const uint8_t* classInfo = NULL;
+    // Note: See JITDwarfEmitter::EmitExceptionTable(...) for corresponding
+    //       dwarf emission
+    // Parse LSDA header.
+    uint8_t lpStartEncoding = *lsda++;
+    const uint8_t* lpStart = (const uint8_t*)readEncodedPointer(&lsda, lpStartEncoding);
+    if (lpStart == 0)
+        lpStart = (const uint8_t*)funcStart;
+    uint8_t ttypeEncoding = *lsda++;
+    if (ttypeEncoding != DW_EH_PE_omit)
+    {
+        // Calculate type info locations in emitted dwarf code which
+        // were flagged by type info arguments to llvm.eh.selector
+        // intrinsic
+        uintptr_t classInfoOffset = readULEB128(&lsda);
+        classInfo = lsda + classInfoOffset;
+    }
+    // Walk call-site table looking for range that 
+    // includes current PC. 
+    uint8_t callSiteEncoding = *lsda++;
+#if __arm__
+    (void)callSiteEncoding;  // On arm callSiteEncoding is never used
+#endif
+    uint32_t callSiteTableLength = static_cast<uint32_t>(readULEB128(&lsda));
+    const uint8_t* callSiteTableStart = lsda;
+    const uint8_t* callSiteTableEnd = callSiteTableStart + callSiteTableLength;
+    const uint8_t* actionTableStart = callSiteTableEnd;
+    const uint8_t* callSitePtr = callSiteTableStart;
+    while (callSitePtr < callSiteTableEnd)
+    {
+        // There is one entry per call site.
+#if !__arm__
+        // The call sites are non-overlapping in [start, start+length)
+        // The call sites are ordered in increasing value of start
+        uintptr_t start = readEncodedPointer(&callSitePtr, callSiteEncoding);
+        uintptr_t length = readEncodedPointer(&callSitePtr, callSiteEncoding);
+        uintptr_t landingPad = readEncodedPointer(&callSitePtr, callSiteEncoding);
+        uintptr_t actionEntry = readULEB128(&callSitePtr);
+        if ((start <= ipOffset) && (ipOffset < (start + length)))
+#else  // __arm__
+        // ip is 1-based index into this table
+        uintptr_t landingPad = readULEB128(&callSitePtr);
+        uintptr_t actionEntry = readULEB128(&callSitePtr);
+        if (--ip == 0)
+#endif  // __arm__
+        {
+            // Found the call site containing ip.
+#if !__arm__
+            if (landingPad == 0)
+            {
+                // No handler here
+                results.reason = _URC_CONTINUE_UNWIND;
+                return;
+            }
+            landingPad = (uintptr_t)lpStart + landingPad;
+#else  // __arm__
+            ++landingPad;
+#endif  // __arm__
+            if (actionEntry == 0)
+            {
+                // Found a cleanup
+                // If this is a type 1 or type 2 search, there are no handlers
+                // If this is a type 3 search, you want to install the cleanup.
+                if ((actions & _UA_CLEANUP_PHASE) && !(actions & _UA_HANDLER_FRAME))
+                {
+                    results.ttypeIndex = 0;  // Redundant but clarifying
+                    results.landingPad = landingPad;
+                    results.reason = _URC_HANDLER_FOUND;
+                    return;
+                }
+                // No handler here
+                results.reason = _URC_CONTINUE_UNWIND;
+                return;
+            }
+            // Convert 1-based byte offset into
+            const uint8_t* action = actionTableStart + (actionEntry - 1);
+            // Scan action entries until you find a matching handler, cleanup, or the end of action list
+            while (true)
+            {
+                const uint8_t* actionRecord = action;
+                int64_t ttypeIndex = readSLEB128(&action);
+                if (ttypeIndex > 0)
+                {
+                    // Found a catch, does it actually catch?
+                    // First check for catch (...)
+                    const __shim_type_info* catchType =
+                        get_shim_type_info(static_cast<uint64_t>(ttypeIndex),
+                                           classInfo, ttypeEncoding,
+                                           native_exception, unwind_exception);
+                    if (catchType == 0)
+                    {
+                        // Found catch (...) catches everything, including foreign exceptions
+                        // If this is a type 1 search save state and return _URC_HANDLER_FOUND
+                        // If this is a type 2 search save state and return _URC_HANDLER_FOUND
+                        // If this is a type 3 search !_UA_FORCE_UNWIND, we should have found this in phase 1!
+                        // If this is a type 3 search _UA_FORCE_UNWIND, ignore handler and continue scan
+                        if ((actions & _UA_SEARCH_PHASE) || (actions & _UA_HANDLER_FRAME))
+                        {
+                            // Save state and return _URC_HANDLER_FOUND
+                            results.ttypeIndex = ttypeIndex;
+                            results.actionRecord = actionRecord;
+                            results.landingPad = landingPad;
+                            results.adjustedPtr = get_thrown_object_ptr(unwind_exception);
+                            results.reason = _URC_HANDLER_FOUND;
+                            return;
+                        }
+                        else if (!(actions & _UA_FORCE_UNWIND))
+                        {
+                            // It looks like the exception table has changed
+                            //    on us.  Likely stack corruption!
+                            call_terminate(native_exception, unwind_exception);
+                        }
+                    }
+                    // Else this is a catch (T) clause and will never
+                    //    catch a foreign exception
+                    else if (native_exception)
+                    {
+                        __cxa_exception* exception_header = (__cxa_exception*)(unwind_exception+1) - 1;
+                        void* adjustedPtr = get_thrown_object_ptr(unwind_exception);
+                        const __shim_type_info* excpType =
+                            static_cast<const __shim_type_info*>(exception_header->exceptionType);
+                        if (adjustedPtr == 0 || excpType == 0)
+                        {
+                            // Something very bad happened
+                            call_terminate(native_exception, unwind_exception);
+                        }
+                        if (catchType->can_catch(excpType, adjustedPtr))
+                        {
+                            // Found a matching handler
+                            // If this is a type 1 search save state and return _URC_HANDLER_FOUND
+                            // If this is a type 3 search and !_UA_FORCE_UNWIND, we should have found this in phase 1!
+                            // If this is a type 3 search and _UA_FORCE_UNWIND, ignore handler and continue scan
+                            if (actions & _UA_SEARCH_PHASE)
+                            {
+                                // Save state and return _URC_HANDLER_FOUND
+                                results.ttypeIndex = ttypeIndex;
+                                results.actionRecord = actionRecord;
+                                results.landingPad = landingPad;
+                                results.adjustedPtr = adjustedPtr;
+                                results.reason = _URC_HANDLER_FOUND;
+                                return;
+                            }
+                            else if (!(actions & _UA_FORCE_UNWIND))
+                            {
+                                // It looks like the exception table has changed
+                                //    on us.  Likely stack corruption!
+                                call_terminate(native_exception, unwind_exception);
+                            }
+                        }
+                    }
+                    // Scan next action ...
+                }
+                else if (ttypeIndex < 0)
+                {
+                    // Found an exception spec.  If this is a foreign exception,
+                    //   it is always caught.
+                    if (native_exception)
+                    {
+                        // Does the exception spec catch this native exception?
+                        __cxa_exception* exception_header = (__cxa_exception*)(unwind_exception+1) - 1;
+                        void* adjustedPtr = get_thrown_object_ptr(unwind_exception);
+                        const __shim_type_info* excpType =
+                            static_cast<const __shim_type_info*>(exception_header->exceptionType);
+                        if (adjustedPtr == 0 || excpType == 0)
+                        {
+                            // Something very bad happened
+                            call_terminate(native_exception, unwind_exception);
+                        }
+                        if (exception_spec_can_catch(ttypeIndex, classInfo,
+                                                     ttypeEncoding, excpType,
+                                                     adjustedPtr, unwind_exception))
+                        {
+                            // native exception caught by exception spec
+                            // If this is a type 1 search, save state and return _URC_HANDLER_FOUND
+                            // If this is a type 3 search !_UA_FORCE_UNWIND, we should have found this in phase 1!
+                            // If this is a type 3 search _UA_FORCE_UNWIND, ignore handler and continue scan
+                            if (actions & _UA_SEARCH_PHASE)
+                            {
+                                // Save state and return _URC_HANDLER_FOUND
+                                results.ttypeIndex = ttypeIndex;
+                                results.actionRecord = actionRecord;
+                                results.landingPad = landingPad;
+                                results.adjustedPtr = adjustedPtr;
+                                results.reason = _URC_HANDLER_FOUND;
+                                return;
+                            }
+                            else if (!(actions & _UA_FORCE_UNWIND))
+                            {
+                                // It looks like the exception table has changed
+                                //    on us.  Likely stack corruption!
+                                call_terminate(native_exception, unwind_exception);
+                            }
+                        }
+                    }
+                    else
+                    {
+                        // foreign exception caught by exception spec
+                        // If this is a type 1 search, save state and return _URC_HANDLER_FOUND
+                        // If this is a type 2 search, save state and return _URC_HANDLER_FOUND
+                        // If this is a type 3 search !_UA_FORCE_UNWIND, we should have found this in phase 1!
+                        // If this is a type 3 search _UA_FORCE_UNWIND, ignore handler and continue scan
+                        if ((actions & _UA_SEARCH_PHASE) || (actions & _UA_HANDLER_FRAME))
+                        {
+                            // Save state and return _URC_HANDLER_FOUND
+                            results.ttypeIndex = ttypeIndex;
+                            results.actionRecord = actionRecord;
+                            results.landingPad = landingPad;
+                            results.adjustedPtr = get_thrown_object_ptr(unwind_exception);
+                            results.reason = _URC_HANDLER_FOUND;
+                            return;
+                        }
+                        else if (!(actions & _UA_FORCE_UNWIND))
+                        {
+                            // It looks like the exception table has changed
+                            //    on us.  Likely stack corruption!
+                            call_terminate(native_exception, unwind_exception);
+                        }
+                    }
+                    // Scan next action ...
+                }
+                else  // ttypeIndex == 0
+                {
+                    // Found a cleanup
+                    // If this is a type 1 search, ignore it and continue scan
+                    // If this is a type 2 search, ignore it and continue scan
+                    // If this is a type 3 search, save state and return _URC_HANDLER_FOUND
+                    if ((actions & _UA_CLEANUP_PHASE) && !(actions & _UA_HANDLER_FRAME))
+                    {
+                        // Save state and return _URC_HANDLER_FOUND
+                        results.ttypeIndex = ttypeIndex;
+                        results.actionRecord = actionRecord;
+                        results.landingPad = landingPad;
+                        results.adjustedPtr = get_thrown_object_ptr(unwind_exception);
+                        results.reason = _URC_HANDLER_FOUND;
+                        return;
+                    }
+                }
+                const uint8_t* temp = action;
+                int64_t actionOffset = readSLEB128(&temp);
+                if (actionOffset == 0)
+                {
+                    // End of action list, no matching handler or cleanup found
+                    results.reason = _URC_CONTINUE_UNWIND;
+                    return;
+                }
+                // Go to next action
+                action += actionOffset;
+            }  // there is no break out of this loop, only return
+        }
+#if !__arm__
+        else if (ipOffset < start)
+        {
+            // There is no call site for this ip
+            // Something bad has happened.  We should never get here.
+            // Possible stack corruption.
+            call_terminate(native_exception, unwind_exception);
+        }
+#endif  // !__arm__
+    }  // there might be some tricky cases which break out of this loop
+
+    // It is possible that no eh table entry specify how to handle
+    // this exception. By spec, terminate it immediately.
+    call_terminate(native_exception, unwind_exception);
+}
+
+// public API
+
+/*
+The personality function branches on actions like so:
+
+_UA_SEARCH_PHASE
+
+    If _UA_CLEANUP_PHASE or _UA_HANDLER_FRAME or _UA_FORCE_UNWIND there's
+      an error from above, return _URC_FATAL_PHASE1_ERROR.
+
+    Scan for anything that could stop unwinding:
+
+       1.  A catch clause that will catch this exception
+           (will never catch foreign).
+       2.  A catch (...) (will always catch foreign).
+       3.  An exception spec that will catch this exception
+           (will always catch foreign).
+    If a handler is found
+        If not foreign
+            Save state in header
+        return _URC_HANDLER_FOUND
+    Else a handler not found
+        return _URC_CONTINUE_UNWIND
+
+_UA_CLEANUP_PHASE
+
+    If _UA_HANDLER_FRAME
+        If _UA_FORCE_UNWIND
+            How did this happen?  return _URC_FATAL_PHASE2_ERROR
+        If foreign
+            Do _UA_SEARCH_PHASE to recover state
+        else
+            Recover state from header
+        Transfer control to landing pad.  return _URC_INSTALL_CONTEXT
+    
+    Else
+
+        This branch handles both normal C++ non-catching handlers (cleanups)
+          and forced unwinding.    
+        Scan for anything that can not stop unwinding:
+    
+            1.  A cleanup.
+
+        If a cleanup is found
+            transfer control to it. return _URC_INSTALL_CONTEXT
+        Else a cleanup is not found: return _URC_CONTINUE_UNWIND
+*/
+
+_Unwind_Reason_Code
+#if __arm__
+__gxx_personality_sj0
+#else
+__gxx_personality_v0
+#endif
+                    (int version, _Unwind_Action actions, uint64_t exceptionClass,
+                     _Unwind_Exception* unwind_exception, _Unwind_Context* context)
+{
+    if (version != 1 || unwind_exception == 0 || context == 0)
+        return _URC_FATAL_PHASE1_ERROR;
+    bool native_exception = (exceptionClass     & get_vendor_and_language) ==
+                            (kOurExceptionClass & get_vendor_and_language);
+    scan_results results;
+    if (actions & _UA_SEARCH_PHASE)
+    {
+        // Phase 1 search:  All we're looking for in phase 1 is a handler that
+        //   halts unwinding
+        scan_eh_tab(results, actions, native_exception, unwind_exception, context);
+        if (results.reason == _URC_HANDLER_FOUND)
+        {
+            // Found one.  Can we cache the results somewhere to optimize phase 2?
+            if (native_exception)
+            {
+                __cxa_exception* exception_header = (__cxa_exception*)(unwind_exception+1) - 1;
+                exception_header->handlerSwitchValue = static_cast<int>(results.ttypeIndex);
+                exception_header->actionRecord = results.actionRecord;
+                exception_header->languageSpecificData = results.languageSpecificData;
+                exception_header->catchTemp = reinterpret_cast<void*>(results.landingPad);
+                exception_header->adjustedPtr = results.adjustedPtr;
+            }
+            return _URC_HANDLER_FOUND;
+        }
+        // Did not find a catching-handler.  Return the results of the scan
+        //    (normally _URC_CONTINUE_UNWIND, but could have been _URC_FATAL_PHASE1_ERROR
+        //     if we were called improperly).
+        return results.reason;
+    }
+    if (actions & _UA_CLEANUP_PHASE)
+    {
+        // Phase 2 search:
+        //  Did we find a catching handler in phase 1?
+        if (actions & _UA_HANDLER_FRAME)
+        {
+            // Yes, phase 1 said we have a catching handler here.
+            // Did we cache the results of the scan?
+            if (native_exception)
+            {
+                // Yes, reload the results from the cache.
+                __cxa_exception* exception_header = (__cxa_exception*)(unwind_exception+1) - 1;
+                results.ttypeIndex = exception_header->handlerSwitchValue;
+                results.actionRecord = exception_header->actionRecord;
+                results.languageSpecificData = exception_header->languageSpecificData;
+                results.landingPad = reinterpret_cast<uintptr_t>(exception_header->catchTemp);
+                results.adjustedPtr = exception_header->adjustedPtr;
+            }
+            else
+            {
+                // No, do the scan again to reload the results.
+                scan_eh_tab(results, actions, native_exception, unwind_exception, context);
+                // Phase 1 told us we would find a handler.  Now in Phase 2 we
+                //   didn't find a handler.  The eh table should not be changing!
+                if (results.reason != _URC_HANDLER_FOUND)
+                    call_terminate(native_exception, unwind_exception);
+            }
+            // Jump to the handler
+            set_registers(unwind_exception, context, results);
+            return _URC_INSTALL_CONTEXT;
+        }
+        // Either we didn't do a phase 1 search (due to forced unwinding), or
+        //   phase 1 reported no catching-handlers.
+        // Search for a (non-catching) cleanup
+        scan_eh_tab(results, actions, native_exception, unwind_exception, context);
+        if (results.reason == _URC_HANDLER_FOUND)
+        {
+            // Found a non-catching handler.  Jump to it:
+            set_registers(unwind_exception, context, results);
+            return _URC_INSTALL_CONTEXT;
+        }
+        // Did not find a cleanup.  Return the results of the scan
+        //    (normally _URC_CONTINUE_UNWIND, but could have been _URC_FATAL_PHASE2_ERROR
+        //     if we were called improperly).
+        return results.reason;
+    }
+    // We were called improperly: neither a phase 1 or phase 2 search
+    return _URC_FATAL_PHASE1_ERROR;
+}
+
+__attribute__((noreturn))
+void
+__cxa_call_unexpected(void* arg)
+{
+    _Unwind_Exception* unwind_exception = static_cast<_Unwind_Exception*>(arg);
+    if (unwind_exception == 0)
+        call_terminate(false, unwind_exception);
+    __cxa_begin_catch(unwind_exception);
+    bool native_old_exception =
+        (unwind_exception->exception_class & get_vendor_and_language) ==
+        (kOurExceptionClass                & get_vendor_and_language);
+    std::unexpected_handler u_handler;
+    std::terminate_handler t_handler;
+    __cxa_exception* old_exception_header = 0;
+    int64_t ttypeIndex;
+    const uint8_t* lsda;
+    if (native_old_exception)
+    {
+        old_exception_header = (__cxa_exception*)(unwind_exception+1) - 1;
+        t_handler = old_exception_header->terminateHandler;
+        u_handler = old_exception_header->unexpectedHandler;
+        // If std::__unexpected(u_handler) rethrows the same exception,
+        //   these values get overwritten by the rethrow.  So save them now:
+        ttypeIndex = old_exception_header->handlerSwitchValue;
+        lsda = old_exception_header->languageSpecificData;
+    }
+    else
+    {
+        t_handler = std::get_terminate();
+        u_handler = std::get_unexpected();
+    }
+    try
+    {
+        std::__unexpected(u_handler);
+    }
+    catch (...)
+    {
+        // If the old exception is foreign, then all we can do is terminate.
+        //   We have no way to recover the needed old exception spec.  There's
+        //   no way to pass that information here.  And the personality routine
+        //   can't call us directly and do anything but terminate() if we throw
+        //   from here.
+        if (native_old_exception)
+        {
+            // Have:
+            //   old_exception_header->languageSpecificData
+            //   old_exception_header->actionRecord
+            // Need
+            //   const uint8_t* classInfo
+            //   uint8_t ttypeEncoding
+            uint8_t lpStartEncoding = *lsda++;
+            const uint8_t* lpStart = (const uint8_t*)readEncodedPointer(&lsda, lpStartEncoding);
+            (void)lpStart;  // purposefully unused.  Just needed to increment lsda.
+            uint8_t ttypeEncoding = *lsda++;
+            if (ttypeEncoding == DW_EH_PE_omit)
+                std::__terminate(t_handler);
+            uintptr_t classInfoOffset = readULEB128(&lsda);
+            const uint8_t* classInfo = lsda + classInfoOffset;
+            // Is this new exception catchable by the exception spec at ttypeIndex?
+            // The answer is obviously yes if the new and old exceptions are the same exception
+            // If no
+            //    throw;
+            __cxa_eh_globals* globals = __cxa_get_globals_fast();
+            __cxa_exception* new_exception_header = globals->caughtExceptions;
+            if (new_exception_header == 0)
+                // This shouldn't be able to happen!
+                std::__terminate(t_handler);
+            bool native_new_exception =
+                (new_exception_header->unwindHeader.exception_class & get_vendor_and_language) ==
+                                                (kOurExceptionClass & get_vendor_and_language);
+            void* adjustedPtr;
+            if (native_new_exception && (new_exception_header != old_exception_header))
+            {
+                const __shim_type_info* excpType =
+                    static_cast<const __shim_type_info*>(new_exception_header->exceptionType);
+                adjustedPtr =
+                    new_exception_header->unwindHeader.exception_class == kOurDependentExceptionClass ?
+                        ((__cxa_dependent_exception*)new_exception_header)->primaryException :
+                        new_exception_header + 1;
+                if (!exception_spec_can_catch(ttypeIndex, classInfo, ttypeEncoding,
+                                              excpType, adjustedPtr, unwind_exception))
+                {
+                    // We need to __cxa_end_catch, but for the old exception,
+                    //   not the new one.  This is a little tricky ...
+                    // Disguise new_exception_header as a rethrown exception, but
+                    //   don't actually rethrow it.  This means you can temporarily
+                    //   end the catch clause enclosing new_exception_header without
+                    //   __cxa_end_catch destroying new_exception_header.
+                    new_exception_header->handlerCount = -new_exception_header->handlerCount;
+                    globals->uncaughtExceptions += 1;
+                    // Call __cxa_end_catch for new_exception_header
+                    __cxa_end_catch();
+                    // Call __cxa_end_catch for old_exception_header
+                    __cxa_end_catch();
+                    // Renter this catch clause with new_exception_header
+                    __cxa_begin_catch(&new_exception_header->unwindHeader);
+                    // Rethrow new_exception_header
+                    throw;
+                }
+            }
+            // Will a std::bad_exception be catchable by the exception spec at
+            //   ttypeIndex?
+            // If no
+            //    throw std::bad_exception();
+            const __shim_type_info* excpType =
+                static_cast<const __shim_type_info*>(&typeid(std::bad_exception));
+            std::bad_exception be;
+            adjustedPtr = &be;
+            if (!exception_spec_can_catch(ttypeIndex, classInfo, ttypeEncoding,
+                                          excpType, adjustedPtr, unwind_exception))
+            {
+                // We need to __cxa_end_catch for both the old exception and the
+                //   new exception.  Technically we should do it in that order.
+                //   But it is expedient to do it in the opposite order:
+                // Call __cxa_end_catch for new_exception_header
+                __cxa_end_catch();
+                // Throw std::bad_exception will __cxa_end_catch for
+                //   old_exception_header
+                throw be;
+            }
+        }
+    }
+    std::__terminate(t_handler);
+}
+
+}  // extern "C"
+
+}  // __cxxabiv1