[compiler-rt] [libcxxabi] [libunwind] [runtimes][PAC] Harden unwinding when possible (#138571) (PR #143230)

[Anatoly Trosinenko via llvm-commits]

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@@ -238,7 +282,20 @@ COMPILER_RT_ABI _Unwind_Reason_Code __gcc_personality_v0(
       _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));
+#define LANDING_PAD_DISCRIMINATOR "__gcc_personality_v0'landingPad"
+      size_t PERSONALITY_PTRAUTH_RI_RA(LANDING_PAD_DISCRIMINATOR) landingPad =
+          funcStart + landingPadOffset;
+#if defined(__APPLE__) && __has_feature(ptrauth_qualifier)
+      uintptr_t stack_pointer = _Unwind_GetGR(context, -2);
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atrosinenko wrote:

[nit] It seems like `stackPointer` better aligns with the prevailing naming style of this file.

https://github.com/llvm/llvm-project/pull/143230