252 lines
7.8 KiB
C
252 lines
7.8 KiB
C
/* ===-- gcc_personality_v0.c - Implement __gcc_personality_v0 -------------===
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*
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* The LLVM Compiler Infrastructure
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*
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* This file is distributed under the University of Illinois Open Source
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* License. See LICENSE.TXT for details.
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*
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* ===----------------------------------------------------------------------===
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*
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*/
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include "int_lib.h"
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/*
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* _Unwind_* stuff based on C++ ABI public documentation
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* http://refspecs.freestandards.org/abi-eh-1.21.html
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*/
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typedef enum {
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_URC_NO_REASON = 0,
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_URC_FOREIGN_EXCEPTION_CAUGHT = 1,
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_URC_FATAL_PHASE2_ERROR = 2,
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_URC_FATAL_PHASE1_ERROR = 3,
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_URC_NORMAL_STOP = 4,
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_URC_END_OF_STACK = 5,
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_URC_HANDLER_FOUND = 6,
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_URC_INSTALL_CONTEXT = 7,
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_URC_CONTINUE_UNWIND = 8
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} _Unwind_Reason_Code;
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typedef enum {
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_UA_SEARCH_PHASE = 1,
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_UA_CLEANUP_PHASE = 2,
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_UA_HANDLER_FRAME = 4,
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_UA_FORCE_UNWIND = 8,
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_UA_END_OF_STACK = 16
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} _Unwind_Action;
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typedef struct _Unwind_Context* _Unwind_Context_t;
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struct _Unwind_Exception {
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uint64_t exception_class;
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void (*exception_cleanup)(_Unwind_Reason_Code reason,
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struct _Unwind_Exception* exc);
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uintptr_t private_1;
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uintptr_t private_2;
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};
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extern const uint8_t* _Unwind_GetLanguageSpecificData(_Unwind_Context_t c);
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extern void _Unwind_SetGR(_Unwind_Context_t c, int i, uintptr_t n);
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extern void _Unwind_SetIP(_Unwind_Context_t, uintptr_t new_value);
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extern uintptr_t _Unwind_GetIP(_Unwind_Context_t context);
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extern uintptr_t _Unwind_GetRegionStart(_Unwind_Context_t context);
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/*
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* Pointer encodings documented at:
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* http://refspecs.freestandards.org/LSB_1.3.0/gLSB/gLSB/ehframehdr.html
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*/
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#define DW_EH_PE_omit 0xff /* no data follows */
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#define DW_EH_PE_absptr 0x00
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#define DW_EH_PE_uleb128 0x01
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#define DW_EH_PE_udata2 0x02
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#define DW_EH_PE_udata4 0x03
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#define DW_EH_PE_udata8 0x04
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#define DW_EH_PE_sleb128 0x09
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#define DW_EH_PE_sdata2 0x0A
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#define DW_EH_PE_sdata4 0x0B
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#define DW_EH_PE_sdata8 0x0C
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#define DW_EH_PE_pcrel 0x10
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#define DW_EH_PE_textrel 0x20
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#define DW_EH_PE_datarel 0x30
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#define DW_EH_PE_funcrel 0x40
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#define DW_EH_PE_aligned 0x50
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#define DW_EH_PE_indirect 0x80 /* gcc extension */
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/* read a uleb128 encoded value and advance pointer */
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static uintptr_t readULEB128(const uint8_t** data)
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{
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uintptr_t result = 0;
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uintptr_t shift = 0;
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unsigned char byte;
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const uint8_t* p = *data;
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do {
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byte = *p++;
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result |= (byte & 0x7f) << shift;
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shift += 7;
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} while (byte & 0x80);
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*data = p;
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return result;
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}
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/* read a pointer encoded value and advance pointer */
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static uintptr_t readEncodedPointer(const uint8_t** data, uint8_t encoding)
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{
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const uint8_t* p = *data;
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uintptr_t result = 0;
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if ( encoding == DW_EH_PE_omit )
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return 0;
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/* first get value */
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switch (encoding & 0x0F) {
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case DW_EH_PE_absptr:
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result = *((uintptr_t*)p);
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p += sizeof(uintptr_t);
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break;
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case DW_EH_PE_uleb128:
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result = readULEB128(&p);
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break;
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case DW_EH_PE_udata2:
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result = *((uint16_t*)p);
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p += sizeof(uint16_t);
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break;
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case DW_EH_PE_udata4:
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result = *((uint32_t*)p);
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p += sizeof(uint32_t);
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break;
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case DW_EH_PE_udata8:
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result = *((uint64_t*)p);
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p += sizeof(uint64_t);
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break;
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case DW_EH_PE_sdata2:
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result = *((int16_t*)p);
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p += sizeof(int16_t);
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break;
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case DW_EH_PE_sdata4:
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result = *((int32_t*)p);
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p += sizeof(int32_t);
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break;
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case DW_EH_PE_sdata8:
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result = *((int64_t*)p);
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p += sizeof(int64_t);
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break;
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case DW_EH_PE_sleb128:
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default:
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/* not supported */
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compilerrt_abort();
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break;
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}
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/* then add relative offset */
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switch ( encoding & 0x70 ) {
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case DW_EH_PE_absptr:
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/* do nothing */
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break;
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case DW_EH_PE_pcrel:
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result += (uintptr_t)(*data);
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break;
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case DW_EH_PE_textrel:
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case DW_EH_PE_datarel:
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case DW_EH_PE_funcrel:
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case DW_EH_PE_aligned:
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default:
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/* not supported */
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compilerrt_abort();
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break;
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}
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/* then apply indirection */
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if (encoding & DW_EH_PE_indirect) {
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result = *((uintptr_t*)result);
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}
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*data = p;
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return result;
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}
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/*
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* The C compiler makes references to __gcc_personality_v0 in
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* the dwarf unwind information for translation units that use
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* __attribute__((cleanup(xx))) on local variables.
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* This personality routine is called by the system unwinder
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* on each frame as the stack is unwound during a C++ exception
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* throw through a C function compiled with -fexceptions.
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*/
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#if __arm__
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// the setjump-longjump based exceptions personality routine has a different name
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_Unwind_Reason_Code __gcc_personality_sj0(int version, _Unwind_Action actions,
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uint64_t exceptionClass, struct _Unwind_Exception* exceptionObject,
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_Unwind_Context_t context)
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#else
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_Unwind_Reason_Code __gcc_personality_v0(int version, _Unwind_Action actions,
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uint64_t exceptionClass, struct _Unwind_Exception* exceptionObject,
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_Unwind_Context_t context)
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#endif
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{
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/* Since C does not have catch clauses, there is nothing to do during */
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/* phase 1 (the search phase). */
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if ( actions & _UA_SEARCH_PHASE )
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return _URC_CONTINUE_UNWIND;
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/* There is nothing to do if there is no LSDA for this frame. */
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const uint8_t* lsda = _Unwind_GetLanguageSpecificData(context);
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if ( lsda == NULL )
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return _URC_CONTINUE_UNWIND;
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uintptr_t pc = _Unwind_GetIP(context)-1;
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uintptr_t funcStart = _Unwind_GetRegionStart(context);
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uintptr_t pcOffset = pc - funcStart;
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/* Parse LSDA header. */
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uint8_t lpStartEncoding = *lsda++;
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if (lpStartEncoding != DW_EH_PE_omit) {
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readEncodedPointer(&lsda, lpStartEncoding);
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}
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uint8_t ttypeEncoding = *lsda++;
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if (ttypeEncoding != DW_EH_PE_omit) {
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readULEB128(&lsda);
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}
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/* Walk call-site table looking for range that includes current PC. */
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uint8_t callSiteEncoding = *lsda++;
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uint32_t callSiteTableLength = readULEB128(&lsda);
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const uint8_t* callSiteTableStart = lsda;
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const uint8_t* callSiteTableEnd = callSiteTableStart + callSiteTableLength;
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const uint8_t* p=callSiteTableStart;
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while (p < callSiteTableEnd) {
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uintptr_t start = readEncodedPointer(&p, callSiteEncoding);
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uintptr_t length = readEncodedPointer(&p, callSiteEncoding);
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uintptr_t landingPad = readEncodedPointer(&p, callSiteEncoding);
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readULEB128(&p); /* action value not used for C code */
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if ( landingPad == 0 )
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continue; /* no landing pad for this entry */
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if ( (start <= pcOffset) && (pcOffset < (start+length)) ) {
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/* Found landing pad for the PC.
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* Set Instruction Pointer to so we re-enter function
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* at landing pad. The landing pad is created by the compiler
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* to take two parameters in registers.
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*/
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_Unwind_SetGR(context, __builtin_eh_return_data_regno(0),
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(uintptr_t)exceptionObject);
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_Unwind_SetGR(context, __builtin_eh_return_data_regno(1), 0);
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_Unwind_SetIP(context, funcStart+landingPad);
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return _URC_INSTALL_CONTEXT;
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}
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}
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/* No landing pad found, continue unwinding. */
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return _URC_CONTINUE_UNWIND;
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}
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