[llvm] [Coroutines] fix coroutines + std::unique_ptr with async exceptions validation errors (PR #149691)

[Weibo He via llvm-commits]

================
@@ -0,0 +1,44 @@
+; In coro-split, this coroutine code reduced IR, produced using clang with async-exceptions
+; crashed before fix because of the validation mismatch of Instruction does not dominate all uses!
+; RUN: opt < %s -passes='coro-split' -S
+
+; Function Attrs: presplitcoroutine
+define i8 @"?resuming_on_new_thread@@YA?AUtask@@Vunique_ptr@@@Z"(ptr %0) #0 personality ptr null {
+  invoke void @llvm.seh.scope.begin()
+          to label %2 unwind label %14
+
+2:                                                ; preds = %1
+  %3 = call token @llvm.coro.id(i32 0, ptr null, ptr null, ptr null)
+  %4 = load volatile ptr, ptr null, align 8
+  %5 = call ptr @llvm.coro.begin(token %3, ptr %4)
+  %6 = call token @llvm.coro.save(ptr null)
+  %7 = call i8 @llvm.coro.suspend(token none, i1 false)
+  invoke void @llvm.seh.try.begin()
+          to label %common.ret unwind label %8
+
+common.ret:                                       ; preds = %12, %10, %2
+  ret i8 0
+
+8:                                                ; preds = %2
+  %9 = catchswitch within none [label %10] unwind label %12
+
+10:                                               ; preds = %8
+  %11 = catchpad within %9 [ptr null, i32 0, ptr null]
+  br label %common.ret
+
+12:                                               ; preds = %8
+  %13 = cleanuppad within none []
+  invoke void @llvm.seh.scope.end()
+          to label %common.ret unwind label %14
+
+14:                                               ; preds = %12, %1
+  %15 = cleanuppad within none []
+  store i32 0, ptr %0, align 4
----------------
NewSigma wrote:

It seems you are clearing pointer in `unhandled_exception()`? Could you confirm it?

https://github.com/llvm/llvm-project/pull/149691