Support of SJ/LJ unwinding (for iOS)

lib/builtins/gcc_personality_v0.c

@@ -180,7 +180,7 @@ static uintptr_t readEncodedPointer(const uint8_t** data, uint8_t encoding)
  * on each frame as the stack is unwound during a C++ exception
  * throw through a C function compiled with -fexceptions.
  */
-#if __arm__
+#if defined(__USING_SJLJ_EXCEPTIONS__)
 // the setjump-longjump based exceptions personality routine has a different name
 COMPILER_RT_ABI _Unwind_Reason_Code
 __gcc_personality_sj0(int version, _Unwind_Action actions,
@@ -216,34 +216,66 @@ __gcc_personality_v0(int version, _Unwind_Action actions,
  if (ttypeEncoding != DW_EH_PE_omit) {
  readULEB128(&lsda); 
  }
- /* Walk call-site table looking for range that includes current PC. */
+
+ uintptr_t resumeIp = 0;
  uint8_t callSiteEncoding = *lsda++;
  uint32_t callSiteTableLength = readULEB128(&lsda);
- const uint8_t* callSiteTableStart = lsda;
- const uint8_t* callSiteTableEnd = callSiteTableStart + callSiteTableLength;
- const uint8_t* p=callSiteTableStart;
- while (p < callSiteTableEnd) {
- uintptr_t start = readEncodedPointer(&p, callSiteEncoding);
- uintptr_t length = readEncodedPointer(&p, callSiteEncoding);
- uintptr_t landingPad = readEncodedPointer(&p, callSiteEncoding);
- readULEB128(&p); /* action value not used for C code */
+ const uint8_t* callSite = lsda;
+
+#if defined(__USING_SJLJ_EXCEPTIONS__)
+ (void)callSiteEncoding;
+ (void)callSiteTableLength; 
+ /* The given "IP" is an index into the call-site table, with two
+ exceptions -- -1 means no-action, and 0 means terminate. But
+ since we're using uleb128 values, we've not got random access
+ to the array. */
+ if ((int) pc <= 0)
+ return _URC_CONTINUE_UNWIND;
+ else {
+ uintptr_t csLp;
+ do {
+ csLp = readULEB128(&callSite);
+ readULEB128(&callSite); // skip cs action
+ }
+ while (--pc);
+
+ /* Can never have null landing pad for sjlj -- that would have
+ been indicated by a -1 call site index. */
+ resumeIp = csLp + 1;
+ }
+#else
+ /* Walk call-site table looking for range that includes current PC. */
+ uintptr_t funcStart = _Unwind_GetRegionStart(context);
+ uintptr_t pcOffset = pc - funcStart;
+ const uint8_t* callSiteTableEnd = callSite + callSiteTableLength;
+
+ while (callSite < callSiteTableEnd) {
+ uintptr_t start = readEncodedPointer(&callSite, callSiteEncoding);
+ uintptr_t length = readEncodedPointer(&callSite, callSiteEncoding);
+ uintptr_t landingPad = readEncodedPointer(&callSite, callSiteEncoding);
+ readULEB128(&callSite); /* action value not used for C code */
  if ( landingPad == 0 )
  continue; /* no landing pad for this entry */
  if ( (start <= pcOffset) && (pcOffset < (start+length)) ) {
  /* Found landing pad for the PC.
- * Set Instruction Pointer to so we re-enter function 
+ * Set Instruction Pointer to so we re-enter function
  * at landing pad. The landing pad is created by the compiler
  * to take two parameters in registers.
- */
- _Unwind_SetGR(context, __builtin_eh_return_data_regno(0), 
- (uintptr_t)exceptionObject);
- _Unwind_SetGR(context, __builtin_eh_return_data_regno(1), 0);
- _Unwind_SetIP(context, funcStart+landingPad);
- return _URC_INSTALL_CONTEXT;
+ */
+ resumeIp = funcStart + landingPad;
+ break;
  }
  }
-
- /* No landing pad found, continue unwinding. */
- return _URC_CONTINUE_UNWIND;
+#endif // SJ/LJ
+
+ if (resumeIp == 0)
+ return _URC_CONTINUE_UNWIND;
+ else
+ {
+ _Unwind_SetGR(context, __builtin_eh_return_data_regno (0), (uintptr_t)exceptionObject);
+ _Unwind_SetGR(context, __builtin_eh_return_data_regno (1), 0);
+ _Unwind_SetIP(context, resumeIp);
+ return _URC_INSTALL_CONTEXT;
+ }
 }