[llvm] [clang] [Coroutines] Introduce [[clang::coro_only_destroy_when_complete]] (PR #71014)

[via llvm-commits]

================
@@ -0,0 +1,137 @@
+; RUN: opt < %s -passes='cgscc(coro-split),early-cse,dce,simplifycfg' -S | FileCheck %s
+
+%"struct.std::__n4861::noop_coroutine_promise" = type { i8 }
+%struct.Promise = type { %"struct.std::__n4861::coroutine_handle" }
+%"struct.std::__n4861::coroutine_handle" = type { ptr }
+
+define ptr @foo() #1 {
+entry:
+  %__promise = alloca %struct.Promise, align 8
+  %0 = call token @llvm.coro.id(i32 16, ptr nonnull %__promise, ptr nonnull @foo, ptr null)
+  %1 = call i1 @llvm.coro.alloc(token %0)
+  br i1 %1, label %coro.alloc, label %init.suspend
+
+coro.alloc:                                       ; preds = %entry
+  %2 = tail call i64 @llvm.coro.size.i64()
+  %call = call noalias noundef nonnull ptr @_Znwm(i64 noundef %2) #11
+  br label %init.suspend
+
+init.suspend:                                     ; preds = %entry, %coro.alloc
+  %3 = phi ptr [ null, %entry ], [ %call, %coro.alloc ]
+  %4 = call ptr @llvm.coro.begin(token %0, ptr %3) #12
+  call void @llvm.lifetime.start.p0(i64 8, ptr nonnull %__promise) #3
+  store ptr null, ptr %__promise, align 8
+  %5 = call token @llvm.coro.save(ptr null)
+  %6 = call i8 @llvm.coro.suspend(token %5, i1 false)
+  switch i8 %6, label %coro.ret [
+  i8 0, label %await.suspend
+  i8 1, label %cleanup1
+  ]
+
+await.suspend:                                    ; preds = %init.suspend
+  %7 = call token @llvm.coro.save(ptr null)
+  %8 = call i8 @llvm.coro.suspend(token %7, i1 false)
+  switch i8 %8, label %coro.ret [
+  i8 0, label %await2.suspend
+  i8 1, label %cleanup2
+  ]
+
+await2.suspend:                                   ; preds = %await.suspend
+  %call27 = call ptr @_Z5Innerv() #3
+  %9 = call token @llvm.coro.save(ptr null)
+  %10 = getelementptr inbounds i8, ptr %__promise, i64 -16
+  store ptr %10, ptr %call27, align 8
+  %11 = getelementptr inbounds i8, ptr %call27, i64 -16
+  %12 = call ptr @llvm.coro.subfn.addr(ptr nonnull %11, i8 0)
+  call fastcc void %12(ptr nonnull %11) #3
+  %13 = call i8 @llvm.coro.suspend(token %9, i1 false)
+  switch i8 %13, label %coro.ret [
+  i8 0, label %final.suspend
+  i8 1, label %cleanup3
+  ]
+
+final.suspend:                                    ; preds = %await2.suspend
+  %14 = call ptr @llvm.coro.subfn.addr(ptr nonnull %11, i8 1)
+  call fastcc void %14(ptr nonnull %11) #3
+  %15 = call token @llvm.coro.save(ptr null)
+  %retval.sroa.0.0.copyload.i = load ptr, ptr %__promise, align 8
+  %16 = call ptr @llvm.coro.subfn.addr(ptr %retval.sroa.0.0.copyload.i, i8 0)
+  call fastcc void %16(ptr %retval.sroa.0.0.copyload.i) #3
+  %17 = call i8 @llvm.coro.suspend(token %15, i1 true) #12
+  switch i8 %17, label %coro.ret [
+  i8 0, label %final.ready
+  i8 1, label %cleanup62
+  ]
+
+final.ready:                                      ; preds = %final.suspend
+  call void @exit(i32 noundef 1)
+  unreachable
+
+cleanup1:
+  call void @dtor1()
+  br label %cleanup62
+
+cleanup2:
+  call void @dtor2()
+  br label %cleanup62
+
+cleanup3:
+  call void @dtor3()
+  br label %cleanup62
+
+cleanup62:                                        ; preds = %await2.suspend, %await.suspend, %init.suspend, %final.suspend
+  call void @llvm.lifetime.end.p0(i64 8, ptr nonnull %__promise) #3
+  %18 = call ptr @llvm.coro.free(token %0, ptr %4)
+  %.not = icmp eq ptr %18, null
+  br i1 %.not, label %coro.ret, label %coro.free
+
+coro.free:                                        ; preds = %cleanup62
+  call void @_ZdlPv(ptr noundef nonnull %18) #3
+  br label %coro.ret
+
+coro.ret:                                         ; preds = %coro.free, %cleanup62, %final.suspend, %await2.suspend, %await.suspend, %init.suspend
+  %19 = call i1 @llvm.coro.end(ptr null, i1 false, token none) #12
+  ret ptr %__promise
+}
+
+declare token @llvm.coro.id(i32, ptr readnone, ptr nocapture readonly, ptr) #2
+declare i1 @llvm.coro.alloc(token) #3
+declare dso_local noundef nonnull ptr @_Znwm(i64 noundef) local_unnamed_addr #4
+declare i64 @llvm.coro.size.i64() #5
+declare ptr @llvm.coro.begin(token, ptr writeonly) #3
+declare void @llvm.lifetime.start.p0(i64 immarg, ptr nocapture) #6
+declare token @llvm.coro.save(ptr) #7
+declare void @llvm.lifetime.end.p0(i64 immarg, ptr nocapture) #6
+declare i8 @llvm.coro.suspend(token, i1) #3
+declare ptr @_Z5Innerv() local_unnamed_addr
+declare dso_local void @_ZdlPv(ptr noundef) local_unnamed_addr #8
+declare ptr @llvm.coro.free(token, ptr nocapture readonly) #2
+declare i1 @llvm.coro.end(ptr, i1, token) #3
+declare void @exit(i32 noundef)
+declare ptr @llvm.coro.subfn.addr(ptr nocapture readonly, i8) #10
+declare void @dtor1()
+declare void @dtor2()
+declare void @dtor3()
+
+attributes #0 = { mustprogress nounwind uwtable }
+attributes #1 = { nounwind presplitcoroutine uwtable coro_only_destroy_when_done }
----------------
h-vetinari wrote:

still `_done` not `_complete`

https://github.com/llvm/llvm-project/pull/71014