[SystemZ][z/OS] Make z/OS personality function known (#89679)

This change adds the z/OS personality function to the list of known EH
personality functions. It enables removing of the EH data/labels if the
personality function is not invoked.

Author: redstar

llvm/include/llvm/IR/EHPersonalities.h

@@ -32,7 +32,8 @@ enum class EHPersonality {
   CoreCLR,
   Rust,
   Wasm_CXX,
-  XL_CXX
+  XL_CXX,
+  ZOS_CXX,
 };
 
 /// See if the given exception handling personality function is one

llvm/lib/IR/EHPersonalities.cpp

@@ -42,6 +42,7 @@ EHPersonality llvm::classifyEHPersonality(const Value *Pers) {
       .Case("rust_eh_personality", EHPersonality::Rust)
       .Case("__gxx_wasm_personality_v0", EHPersonality::Wasm_CXX)
       .Case("__xlcxx_personality_v1", EHPersonality::XL_CXX)
+      .Case("__zos_cxx_personality_v2", EHPersonality::ZOS_CXX)
       .Default(EHPersonality::Unknown);
 }
 
@@ -73,6 +74,8 @@ StringRef llvm::getEHPersonalityName(EHPersonality Pers) {
     return "__gxx_wasm_personality_v0";
   case EHPersonality::XL_CXX:
     return "__xlcxx_personality_v1";
+  case EHPersonality::ZOS_CXX:
+    return "__zos_cxx_personality_v2";
   case EHPersonality::Unknown:
     llvm_unreachable("Unknown EHPersonality!");
   }

llvm/lib/Transforms/InstCombine/InstructionCombining.cpp

@@ -3972,6 +3972,7 @@ static bool isCatchAll(EHPersonality Personality, Constant *TypeInfo) {
   case EHPersonality::CoreCLR:
   case EHPersonality::Wasm_CXX:
   case EHPersonality::XL_CXX:
+  case EHPersonality::ZOS_CXX:
     return TypeInfo->isNullValue();
   }
   llvm_unreachable("invalid enum");

llvm/test/CodeGen/SystemZ/zos-no-eh-label.ll

@@ -0,0 +1,12 @@
+; RUN: llc -mtriple s390x-ibm-zos < %s | FileCheck %s
+
+define signext i32 @_Z9computeitv() personality ptr @__zos_cxx_personality_v2 {
+  ret i32 0
+}
+
+declare i32 @__zos_cxx_personality_v2(...)
+
+; The personality function is unused, therefore check that it is not referenced.
+; There should also be no exception table.
+; CHECK-NOT: __zos_cxx_personality_v2
+; CHECK-NOT: GCC_except_table