[libunwind] Rename __personality_routine to _Unwind_Personality_Fn

[zero9178]

Summary

This patch renames personality_routine to _Unwind_Personality_Fn in unwind.h. Both unwind.h from clang and GCC headers use this name instead of __personality_routine. With this patch one is also able to build libc++abi with libunwind support on Windows.

Would need someone to commit this for me if accepted.

[compnerd]

Why not rename __personality_routine to _Unwind_Personality_Fn? I don't think that _Unwind_Personality_Fn is part of either the ABI-EH, gABI, or PSABI, but, it is acceptable for GCC compatibility.

[zero9178]

Instead of changing the libunwind header to contain _Unwind_Personality_Fn, changed libcxxabi to use __personality_routine

[mstorsjo]

In D73584#1853124, @zero9178 wrote:

Instead of changing the libunwind header to contain _Unwind_Personality_Fn, changed libcxxabi to use __personality_routine

Hmm, this isn't quite the way I interpreted @compnerd's comment

In D73584#1853050, @compnerd wrote:

Why not rename __personality_routine to _Unwind_Personality_Fn? I don't think that _Unwind_Personality_Fn is part of either the ABI-EH, gABI, or PSABI, but, it is acceptable for GCC compatibility.

I interpret this as suggesting changing the instances of __personality_routine to _Unwind_Personality_Fn, instead of adding a new typedef (as you did in the previous iteration of the patch).

[mstorsjo]

In D73584#1853294, @mstorsjo wrote:

In D73584#1853124, @zero9178 wrote:

Instead of changing the libunwind header to contain _Unwind_Personality_Fn, changed libcxxabi to use __personality_routine

Hmm, this isn't quite the way I interpreted @compnerd's comment

In D73584#1853050, @compnerd wrote:

Why not rename __personality_routine to _Unwind_Personality_Fn? I don't think that _Unwind_Personality_Fn is part of either the ABI-EH, gABI, or PSABI, but, it is acceptable for GCC compatibility.

I interpret this as suggesting changing the instances of __personality_routine to _Unwind_Personality_Fn, instead of adding a new typedef (as you did in the previous iteration of the patch).

... although I see that isn't easily doable, as libuwind is full of use of that type.

[zero9178]

As far as I understand __personality_routine is the way the various standards call it, so introducing a GCC specific typedef seems unnecessary and not portable to me

[compnerd]

I think that we would want to retain the ability to build libc++abi against libgcc_s. If that also vends a __personality_routine type, then this would definitely be preferable.

[mstorsjo]

In D73584#1853695, @compnerd wrote:

I think that we would want to retain the ability to build libc++abi against libgcc_s. If that also vends a __personality_routine type, then this would definitely be preferable.

Grepping in gcc.git gives me no hits for __personality_routine, so standard or not, we should probably keep using the gcc name for the typedef here then, and provide both in libunwind's header.

[zero9178]

Just noticed that the unwind.h header of gcc does not provide a __personality_routine typedef. So we have 3 different unwind.h headers.

• unwind.h from libunwind: Defines __personality_routine but not _Unwind_Personality_Fn
• unwind.h from clang Headers: Defines both
• unwind.h from GCC Headers: Defines only _Unwind_Personality_Fn

Not quite sure how to handle this I must say. Maybe adding _Unwind_Personality_Fn to libunwind after all wouldn't be too bad

[steven_wu]

I don't really mind either way. If you are using clang, you are really not expecting to use <unwind.h> in libunwind without going through the clang header, which has both versions defined.

[zero9178]

Reverted back to defining _Unwind_Personality_Fn in unwind.h

[compnerd]

I think that we should switch everything to just _Unwind_Personality_Fn and remove __personality_routine.

[zero9178]

Refactored all uses of __personality_routine to _Unwind_Personality_Fn

[steven_wu]

I hope we are not renaming everything because it add complexity on compatibility.

Rename only the refs from libunwind is not enough since there are refs from clang header and libc++abi as well. unwind.h and corresponding header from clang are both shipping products which add compatibility problem.

[zero9178]

In D73584#1862110, @steven_wu wrote:

I hope we are not renaming everything because it add complexity on compatibility.

Rename only the refs from libunwind is not enough since there are refs from clang header and libc++abi as well. unwind.h and corresponding header from clang are both shipping products which add compatibility problem.

Git grepping for __ personality_routine after the patch yields only three results. One is the typedef inside of the clang Headers, Two are inside of tests of llvm that I am not sure are relevant here. libc++abi uses the name _Unwind_Personality_Fn instead of __personality_routine that libunwind has used prior to this patch. _Unwind_Personality_Fn is also what GCC calls it. So this patch actually makes it possible to compile libc++abi with libunwind (Build errors only show up on windows since only windows has actually used _Unwind_Personality_Fn ).

Regarding compatibility I am not sure, but I thought users are expected to include unwind.h from clang Headers anyways.

[steven_wu]

In D73584#1862464, @zero9178 wrote:

In D73584#1862110, @steven_wu wrote:

I hope we are not renaming everything because it add complexity on compatibility.

Rename only the refs from libunwind is not enough since there are refs from clang header and libc++abi as well. unwind.h and corresponding header from clang are both shipping products which add compatibility problem.

Git grepping for __ personality_routine after the patch yields only three results. One is the typedef inside of the clang Headers, Two are inside of tests of llvm that I am not sure are relevant here. libc++abi uses the name _Unwind_Personality_Fn instead of __personality_routine that libunwind has used prior to this patch. _Unwind_Personality_Fn is also what GCC calls it. So this patch actually makes it possible to compile libc++abi with libunwind (Build errors only show up on windows since only windows has actually used _Unwind_Personality_Fn ).

Regarding compatibility I am not sure, but I thought users are expected to include unwind.h from clang Headers anyways.

Won't the typedef in clang header turns into an error? That is also the compatibility problem. If you have a mismatch between clang header and libunwind header, it is going to break one way or the other.

[compnerd]

In D73584#1862820, @steven_wu wrote:

In D73584#1862464, @zero9178 wrote:

In D73584#1862110, @steven_wu wrote:

I hope we are not renaming everything because it add complexity on compatibility.

Rename only the refs from libunwind is not enough since there are refs from clang header and libc++abi as well. unwind.h and corresponding header from clang are both shipping products which add compatibility problem.

Git grepping for __ personality_routine after the patch yields only three results. One is the typedef inside of the clang Headers, Two are inside of tests of llvm that I am not sure are relevant here. libc++abi uses the name _Unwind_Personality_Fn instead of __personality_routine that libunwind has used prior to this patch. _Unwind_Personality_Fn is also what GCC calls it. So this patch actually makes it possible to compile libc++abi with libunwind (Build errors only show up on windows since only windows has actually used _Unwind_Personality_Fn ).

Regarding compatibility I am not sure, but I thought users are expected to include unwind.h from clang Headers anyways.

Won't the typedef in clang header turns into an error? That is also the compatibility problem. If you have a mismatch between clang header and libunwind header, it is going to break one way or the other.

I don't think that is a real concern - the typedef is local, and references a local definition (that is, clang's unwind.h defines both __Unwind_Personality_Fn and __personality_routine).

Furthermore, @zero9178 didn't mention that the local definition that exists actually is under a preprocessor macro for ARM EHABI specifically. So you are looking at a mismatch on ARM (GNU)EABI environments where it would have previously caused an error already in K&R, ANSI, or C89 due to the type redefinition. In C99 or newer, the type redefinition is permitted and then the type alias will reference the locally declared function type. This is all ignoring the fact that mixing and matching the headers like that is already prone to errors.

I believe that the patch in the current incarnation is the right approach.

[steven_wu]

I see. I don't really care then. LGTM!

[zero9178]

Thank you! Would need someone to commit this for me

[compnerd]

rG14798b44658

libunwind/include/unwind.h

struct _Unwind_Control_Block {
   long long int :0; /* Enforce the 8-byte alignment */
 } __attribute__((__aligned__(8)));
 
 typedef _Unwind_Reason_Code (*_Unwind_Stop_Fn)
       (_Unwind_State state,
        _Unwind_Exception* exceptionObject,
        struct _Unwind_Context* context);
 
-typedef _Unwind_Reason_Code (*__personality_routine)
-      (_Unwind_State state,
-       _Unwind_Exception* exceptionObject,
-       struct _Unwind_Context* context);
+typedef _Unwind_Reason_Code (*_Unwind_Personality_Fn)(
+    _Unwind_State state, _Unwind_Exception *exceptionObject,
+    struct _Unwind_Context *context);
 #else
 struct _Unwind_Context;   // opaque
 struct _Unwind_Exception; // forward declaration
 typedef struct _Unwind_Exception _Unwind_Exception;
 
 struct _Unwind_Exception {
   uint64_t exception_class;
   void (*exception_cleanup)(_Unwind_Reason_Code reason,

 typedef _Unwind_Reason_Code (*_Unwind_Stop_Fn)
     (int version,
      _Unwind_Action actions,
      uint64_t exceptionClass,
      _Unwind_Exception* exceptionObject,
      struct _Unwind_Context* context,
      void* stop_parameter );
 
-typedef _Unwind_Reason_Code (*__personality_routine)
-      (int version,
-       _Unwind_Action actions,
-       uint64_t exceptionClass,
-       _Unwind_Exception* exceptionObject,
-       struct _Unwind_Context* context);
+typedef _Unwind_Reason_Code (*_Unwind_Personality_Fn)(
+    int version, _Unwind_Action actions, uint64_t exceptionClass,
+    _Unwind_Exception *exceptionObject, struct _Unwind_Context *context);
 #endif
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 //
 // The following are the base functions documented by the C++ ABI

 typedef struct _EXCEPTION_RECORD EXCEPTION_RECORD;
 typedef struct _CONTEXT CONTEXT;
 typedef struct _DISPATCHER_CONTEXT DISPATCHER_CONTEXT;
 #elif !defined(__MINGW32__) && VER_PRODUCTBUILD < 8000
 typedef struct _DISPATCHER_CONTEXT DISPATCHER_CONTEXT;
 #endif
 // This is the common wrapper for GCC-style personality functions with SEH.
 extern EXCEPTION_DISPOSITION _GCC_specific_handler(EXCEPTION_RECORD *exc,
-                                                   void *frame,
-                                                   CONTEXT *ctx,
+                                                   void *frame, CONTEXT *ctx,
                                                    DISPATCHER_CONTEXT *disp,
-                                                   __personality_routine pers);
+                                                   _Unwind_Personality_Fn pers);
 #endif
 
 #ifdef __cplusplus
 }
 #endif
 
 #endif // __UNWIND_H__

libunwind/src/Unwind-EHABI.cpp

if (_LIBUNWIND_TRACING_UNWINDING) {
           static_cast<void *>(exception_object), pc,
           frameInfo.start_ip, functionName,
           frameInfo.lsda, frameInfo.handler);
     }
 
     // If there is a personality routine, ask it if it will want to stop at
     // this frame.
     if (frameInfo.handler != 0) {
-      __personality_routine p =
-          (__personality_routine)(long)(frameInfo.handler);
+      _Unwind_Personality_Fn p =
+          (_Unwind_Personality_Fn)(long)(frameInfo.handler);
       _LIBUNWIND_TRACE_UNWINDING(
           "unwind_phase1(ex_ojb=%p): calling personality function %p",
           static_cast<void *>(exception_object),
           reinterpret_cast<void *>(reinterpret_cast<uintptr_t>(p)));
       struct _Unwind_Context *context = (struct _Unwind_Context *)(cursor);
       exception_object->pr_cache.fnstart = frameInfo.start_ip;
       exception_object->pr_cache.ehtp =
           (_Unwind_EHT_Header *)frameInfo.unwind_info;
if (_LIBUNWIND_TRACING_UNWINDING) {
           "lsda=0x%" PRIxPTR ", personality=0x%" PRIxPTR "",
           static_cast<void *>(exception_object), frameInfo.start_ip,
           functionName, sp, frameInfo.lsda,
           frameInfo.handler);
     }
 
     // If there is a personality routine, tell it we are unwinding.
     if (frameInfo.handler != 0) {
-      __personality_routine p =
-          (__personality_routine)(long)(frameInfo.handler);
+      _Unwind_Personality_Fn p =
+          (_Unwind_Personality_Fn)(long)(frameInfo.handler);
       struct _Unwind_Context *context = (struct _Unwind_Context *)(cursor);
       // EHABI #7.2
       exception_object->pr_cache.fnstart = frameInfo.start_ip;
       exception_object->pr_cache.ehtp =
           (_Unwind_EHT_Header *)frameInfo.unwind_info;
       exception_object->pr_cache.additional = frameInfo.flags;
       _Unwind_Reason_Code personalityResult =
           (*p)(state, exception_object, context);

libunwind/src/Unwind-seh.cpp

static void __unw_seh_set_disp_ctx(unw_cursor_t *cursor,
                                    DISPATCHER_CONTEXT *disp);
 
 /// Common implementation of SEH-style handler functions used by Itanium-
 /// style frames.  Depending on how and why it was called, it may do one of:
 ///  a) Delegate to the given Itanium-style personality function; or
 ///  b) Initiate a collided unwind to halt unwinding.
 _LIBUNWIND_EXPORT EXCEPTION_DISPOSITION
 _GCC_specific_handler(PEXCEPTION_RECORD ms_exc, PVOID frame, PCONTEXT ms_ctx,
-                      DISPATCHER_CONTEXT *disp, __personality_routine pers) {
+                      DISPATCHER_CONTEXT *disp, _Unwind_Personality_Fn pers) {
   unw_cursor_t cursor;
   _Unwind_Exception *exc;
   _Unwind_Action action;
   struct _Unwind_Context *ctx = nullptr;
   _Unwind_Reason_Code urc;
   uintptr_t retval, target;
   bool ours = false;
 
if (stopResult != _URC_NO_REASON) {
       _LIBUNWIND_TRACE_UNWINDING(
           "unwind_phase2_forced(ex_ojb=%p): stopped by stop function",
           (void *)exception_object);
       return _URC_FATAL_PHASE2_ERROR;
     }
 
     // If there is a personality routine, tell it we are unwinding.
     if (frameInfo.handler != 0) {
-      __personality_routine p =
-          (__personality_routine)(intptr_t)(frameInfo.handler);
+      _Unwind_Personality_Fn p =
+          (_Unwind_Personality_Fn)(intptr_t)(frameInfo.handler);
       _LIBUNWIND_TRACE_UNWINDING(
           "unwind_phase2_forced(ex_ojb=%p): calling personality function %p",
           (void *)exception_object, (void *)(uintptr_t)p);
       _Unwind_Reason_Code personalityResult =
           (*p)(1, action, exception_object->exception_class, exception_object,
                (struct _Unwind_Context *)(&cursor2));
       switch (personalityResult) {
       case _URC_CONTINUE_UNWIND:

libunwind/src/Unwind-sjlj.c

struct _Unwind_FunctionContext {
 
   // set by calling function before registering to be the landing pad
   uint32_t                        resumeLocation;
 
   // set by personality handler to be parameters passed to landing pad function
   uint32_t                        resumeParameters[4];
 
   // set by calling function before registering
-  __personality_routine           personality; // arm offset=24
+  _Unwind_Personality_Fn personality;          // arm offset=24
   uintptr_t                       lsda;        // arm offset=28
 
   // variable length array, contains registers to restore
   // 0 = r7, 1 = pc, 2 = sp
   void                           *jbuf[];
 };
 
 #if defined(_LIBUNWIND_HAS_NO_THREADS)
if (stopResult != _URC_NO_REASON) {
       _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): "
                                  "stopped by stop function",
                                  (void *)exception_object);
       return _URC_FATAL_PHASE2_ERROR;
     }
 
     // if there is a personality routine, tell it we are unwinding
     if (c->personality != NULL) {
-      __personality_routine p = (__personality_routine) c->personality;
+      _Unwind_Personality_Fn p = (_Unwind_Personality_Fn)c->personality;
       _LIBUNWIND_TRACE_UNWINDING("unwind_phase2_forced(ex_ojb=%p): "
                                  "calling personality function %p",
                                  (void *)exception_object, (void *)p);
       _Unwind_Reason_Code personalityResult =
           (*p)(1, action, exception_object->exception_class, exception_object,
                (struct _Unwind_Context *)c);
       switch (personalityResult) {
       case _URC_CONTINUE_UNWIND:

libunwind/src/UnwindLevel1-gcc-ext.c

#else
     // Update the pr_cache in the mock exception object.
     const uint32_t* unwindInfo = (uint32_t *) frameInfo.unwind_info;
     ex.pr_cache.fnstart = frameInfo.start_ip;
     ex.pr_cache.ehtp = (_Unwind_EHT_Header *) unwindInfo;
     ex.pr_cache.additional= frameInfo.flags;
 
     struct _Unwind_Context *context = (struct _Unwind_Context *)&cursor;
     // Get and call the personality function to unwind the frame.
-    __personality_routine handler = (__personality_routine) frameInfo.handler;
+    _Unwind_Personality_Fn handler = (_Unwind_Personality_Fn)frameInfo.handler;
     if (handler == NULL) {
       return _URC_END_OF_STACK;
     }
     if (handler(_US_VIRTUAL_UNWIND_FRAME | _US_FORCE_UNWIND, &ex, context) !=
             _URC_CONTINUE_UNWIND) {
       return _URC_END_OF_STACK;
     }
 #endif // defined(_LIBUNWIND_ARM_EHABI)

libunwind/src/UnwindLevel1.c

if (_LIBUNWIND_TRACING_UNWINDING) {
           ", func=%s, lsda=0x%" PRIxPTR ", personality=0x%" PRIxPTR "",
           (void *)exception_object, pc, frameInfo.start_ip, functionName,
           frameInfo.lsda, frameInfo.handler);
     }
 
     // If there is a personality routine, ask it if it will want to stop at
     // this frame.
     if (frameInfo.handler != 0) {
-      __personality_routine p =
-          (__personality_routine)(uintptr_t)(frameInfo.handler);
+      _Unwind_Personality_Fn p =
+          (_Unwind_Personality_Fn)(uintptr_t)(frameInfo.handler);
       _LIBUNWIND_TRACE_UNWINDING(
           "unwind_phase1(ex_ojb=%p): calling personality function %p",
           (void *)exception_object, (void *)(uintptr_t)p);
       _Unwind_Reason_Code personalityResult =
           (*p)(1, _UA_SEARCH_PHASE, exception_object->exception_class,
                exception_object, (struct _Unwind_Context *)(cursor));
       switch (personalityResult) {
       case _URC_HANDLER_FOUND:
if (_LIBUNWIND_TRACING_UNWINDING) {
                                  ", personality=0x%" PRIxPTR,
                                  (void *)exception_object, frameInfo.start_ip,
                                  functionName, sp, frameInfo.lsda,
                                  frameInfo.handler);
     }
 
     // If there is a personality routine, tell it we are unwinding.
     if (frameInfo.handler != 0) {
-      __personality_routine p =
-          (__personality_routine)(uintptr_t)(frameInfo.handler);
+      _Unwind_Personality_Fn p =
+          (_Unwind_Personality_Fn)(uintptr_t)(frameInfo.handler);
       _Unwind_Action action = _UA_CLEANUP_PHASE;
       if (sp == exception_object->private_2) {
         // Tell personality this was the frame it marked in phase 1.
         action = (_Unwind_Action)(_UA_CLEANUP_PHASE | _UA_HANDLER_FRAME);
       }
        _Unwind_Reason_Code personalityResult =
           (*p)(1, action, exception_object->exception_class, exception_object,
                (struct _Unwind_Context *)(cursor));
if (stopResult != _URC_NO_REASON) {
       _LIBUNWIND_TRACE_UNWINDING(
           "unwind_phase2_forced(ex_ojb=%p): stopped by stop function",
           (void *)exception_object);
       return _URC_FATAL_PHASE2_ERROR;
     }
 
     // If there is a personality routine, tell it we are unwinding.
     if (frameInfo.handler != 0) {
-      __personality_routine p =
-          (__personality_routine)(intptr_t)(frameInfo.handler);
+      _Unwind_Personality_Fn p =
+          (_Unwind_Personality_Fn)(intptr_t)(frameInfo.handler);
       _LIBUNWIND_TRACE_UNWINDING(
           "unwind_phase2_forced(ex_ojb=%p): calling personality function %p",
           (void *)exception_object, (void *)(uintptr_t)p);
       _Unwind_Reason_Code personalityResult =
           (*p)(1, action, exception_object->exception_class, exception_object,
                (struct _Unwind_Context *)(cursor));
       switch (personalityResult) {
       case _URC_CONTINUE_UNWIND: