[libunwind] Sync Unwind_AppleExtras.cpp with downstream version

[ldionne]

Summary

Both had diverged in a few ways, so this brings them both back in sync.

[mstorsjo]

LGTM

[ldionne]

Rebase onto main

[ldionne]

CI failures are flakes, shipping.

libunwind/src/Unwind_AppleExtras.cpp

 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //
 //===----------------------------------------------------------------------===//
 
 #include "config.h"
 
+#include <TargetConditionals.h>
+
 
 // static linker symbols to prevent wrong two level namespace for _Unwind symbols
 #if defined(__arm__)
-   #define NOT_HERE_BEFORE_5_0(sym)     \
+#  if defined(__USING_SJLJ_EXCEPTIONS__) && TARGET_OS_IOS
+#     define NOT_HERE_BEFORE_5_0(sym)     \
        extern const char sym##_tmp30 __asm("$ld$hide$os3.0$_" #sym ); \
        __attribute__((visibility("default"))) const char sym##_tmp30 = 0; \
        extern const char sym##_tmp31 __asm("$ld$hide$os3.1$_" #sym ); \
           __attribute__((visibility("default"))) const char sym##_tmp31 = 0; \
        extern const char sym##_tmp32 __asm("$ld$hide$os3.2$_" #sym );\
            __attribute__((visibility("default"))) const char sym##_tmp32 = 0; \
        extern const char sym##_tmp40 __asm("$ld$hide$os4.0$_" #sym ); \
           __attribute__((visibility("default"))) const char sym##_tmp40 = 0; \
        extern const char sym##_tmp41 __asm("$ld$hide$os4.1$_" #sym ); \
           __attribute__((visibility("default"))) const char sym##_tmp41 = 0; \
        extern const char sym##_tmp42 __asm("$ld$hide$os4.2$_" #sym ); \
           __attribute__((visibility("default"))) const char sym##_tmp42 = 0; \
        extern const char sym##_tmp43 __asm("$ld$hide$os4.3$_" #sym ); \
           __attribute__((visibility("default"))) const char sym##_tmp43 = 0;
-#elif defined(__aarch64__)
-  #define NOT_HERE_BEFORE_10_6(sym)
-  #define NEVER_HERE(sym)
-#else
-  #define NOT_HERE_BEFORE_10_6(sym) \
+#  else // defined(__USING_SJLJ_EXCEPTIONS__) && TARGET_OS_IOS
+#     define NOT_HERE_BEFORE_5_0(sym)
+#     define NOT_HERE_BEFORE_10_6(sym)
+#     define NEVER_HERE(sym)
+#  endif // defined(__USING_SJLJ_EXCEPTIONS__) && TARGET_OS_IOS
+#elif TARGET_OS_OSX && !defined(__aarch64__)
+#  define NOT_HERE_BEFORE_10_6(sym) \
     extern const char sym##_tmp4 __asm("$ld$hide$os10.4$_" #sym ); \
           __attribute__((visibility("default"))) const char sym##_tmp4 = 0; \
     extern const char sym##_tmp5 __asm("$ld$hide$os10.5$_" #sym ); \
           __attribute__((visibility("default"))) const char sym##_tmp5 = 0;
-  #define NEVER_HERE(sym) \
+#  define NEVER_HERE(sym) \
     extern const char sym##_tmp4 __asm("$ld$hide$os10.4$_" #sym ); \
           __attribute__((visibility("default"))) const char sym##_tmp4 = 0; \
     extern const char sym##_tmp5 __asm("$ld$hide$os10.5$_" #sym ); \
           __attribute__((visibility("default"))) const char sym##_tmp5 = 0; \
     extern const char sym##_tmp6 __asm("$ld$hide$os10.6$_" #sym ); \
           __attribute__((visibility("default"))) const char sym##_tmp6 = 0;
+#else
+#  define NOT_HERE_BEFORE_10_6(sym)
+#  define NEVER_HERE(sym)
 #endif
 
 
 #if defined(_LIBUNWIND_BUILD_ZERO_COST_APIS)
 
 //
 // symbols in libSystem.dylib in 10.6 and later, but are in libgcc_s.dylib in
 // earlier versions