[Runtime][Test] Add a leading underscore to swift_exceptionPersonality.

The other new runtime functions appear to have a leading underscore.
It makes sense in this case because we don't expect anything to call
this directly (other than the unwinder).

rdar://120952971

Author: al45tair

include/swift/Runtime/RuntimeFunctions.def

@@ -2807,13 +2807,13 @@ FUNCTION(InitRawStructMetadata,
          EFFECT(MetaData),
          UNKNOWN_MEMEFFECTS)
 
-// _Unwind_Reason_Code swift_exceptionPersonality(int version,
-//                                                _Unwind_Action actions,
-//                                                uint64 exceptionClass,
-//                                                struct _Unwind_Exception *exceptionObject,
-//                                                struct _Unwind_Context *context);
+// _Unwind_Reason_Code _swift_exceptionPersonality(int version,
+//                                                 _Unwind_Action actions,
+//                                                 uint64 exceptionClass,
+//                                                 struct _Unwind_Exception *exceptionObject,
+//                                                 struct _Unwind_Context *context);
 FUNCTION(ExceptionPersonality,
-         swift_exceptionPersonality,
+         _swift_exceptionPersonality,
          C_CC, AlwaysAvailable,
          RETURNS(Int32Ty),
          ARGS(Int32Ty,

stdlib/public/runtime/Exception.cpp

@@ -33,11 +33,11 @@ using namespace swift;
 extern "C" void __cxa_begin_catch(void *);
 
 SWIFT_RUNTIME_STDLIB_API _Unwind_Reason_Code
-swift_exceptionPersonality(int version,
-                           _Unwind_Action actions,
-                           uint64_t exceptionClass,
-                           struct _Unwind_Exception *exceptionObject,
-                           struct _Unwind_Context *context)
+_swift_exceptionPersonality(int version,
+                            _Unwind_Action actions,
+                            uint64_t exceptionClass,
+                            struct _Unwind_Exception *exceptionObject,
+                            struct _Unwind_Context *context)
 {
   // Handle exceptions by catching them and calling std::terminate().
   // This, in turn, will trigger the unhandled exception routine in the

test/Interop/Cxx/exceptions/objc-trap-on-exception-irgen-itanium.swift

@@ -32,7 +32,7 @@ func testObjCMethodCall() {
 
 testObjCMethodCall()
 
-// CHECK: define {{.*}} @"$s4test0A14ObjCMethodCallyyF"() #[[#UWATTR:]] personality ptr @swift_exceptionPersonality
+// CHECK: define {{.*}} @"$s4test0A14ObjCMethodCallyyF"() #[[#UWATTR:]] personality ptr @_swift_exceptionPersonality
 // CHECK: invoke void {{.*}}@objc_msgSend
 // CHECK-NEXT: to label %[[CONT1:.*]] unwind label %[[UNWIND1:.*]]
 // CHECK-EMPTY:

test/Interop/Cxx/exceptions/trap-on-exception-irgen-itanium.swift

@@ -309,7 +309,7 @@ public func test() {
 // CHECK-NEXT:  ret i32
 // CHECK-NEXT: }
 
-// CHECK: define {{.*}} @"$s4test0A17FreeFunctionCallss5Int32VyF"() #[[#SWIFTUWMETA:]] personality ptr @swift_exceptionPersonality
+// CHECK: define {{.*}} @"$s4test0A17FreeFunctionCallss5Int32VyF"() #[[#SWIFTUWMETA:]] personality ptr @_swift_exceptionPersonality
 // CHECK:   invoke i32 @_Z18freeFunctionThrowsi(i32 0)
 // CHECK-NEXT:  to label %[[CONT1:.*]] unwind label %[[UNWIND1:.*]]
 // CHECK-EMPTY:
@@ -335,7 +335,7 @@ public func test() {
 // CHECK-NEXT: unreachable
 // CHECK-NEXT: }
 
-// CHECK: i32 @__gxx_personality_v0(...)
+// CHECK: i32 @_swift_exceptionPersonality(...)
 
 // CHECK: define {{.*}} @"$s4test0A11MethodCallss5Int32VyF"() #[[#SWIFTUWMETA]] personality
 // CHECK: call swiftcc i32 @"$s4test8makeCInts5Int32VyF"()

test/abi/macOS/arm64/stdlib.swift

@@ -254,4 +254,4 @@ Added: __swift_pod_destroy
 Added: __swift_pod_direct_initializeBufferWithCopyOfBuffer
 Added: __swift_pod_indirect_initializeBufferWithCopyOfBuffer
 Added: __swift_validatePrespecializedMetadata
-Added: _swift_exceptionPersonality
+Added: __swift_exceptionPersonality

test/abi/macOS/x86_64/stdlib.swift

@@ -254,5 +254,5 @@ Added: __swift_pod_destroy
 Added: __swift_pod_direct_initializeBufferWithCopyOfBuffer
 Added: __swift_pod_indirect_initializeBufferWithCopyOfBuffer
 Added: __swift_validatePrespecializedMetadata
-Added: _swift_exceptionPersonality
+Added: __swift_exceptionPersonality