diff --git a/src/core/lib/promise/detail/join_state.h b/src/core/lib/promise/detail/join_state.h
index 7dffa8b255d..d6ce8782bfa 100644
--- a/src/core/lib/promise/detail/join_state.h
+++ b/src/core/lib/promise/detail/join_state.h
@@ -65,18 +65,10 @@ struct JoinState<Traits, P0, P1> {
   }
   JoinState& operator=(const JoinState& other) = delete;
   JoinState& operator=(JoinState&& other) = delete;
-  GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION JoinState(JoinState&& other) noexcept
-      : ready(other.ready) {
-    if (ready.is_set(0)) {
-      Construct(&result0, std::move(other.result0));
-    } else {
-      Construct(&promise0, std::move(other.promise0));
-    }
-    if (ready.is_set(1)) {
-      Construct(&result1, std::move(other.result1));
-    } else {
-      Construct(&promise1, std::move(other.promise1));
-    }
+  GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION JoinState(JoinState&& other) noexcept {
+    DCHECK(other.ready.none());
+    Construct(&promise0, std::move(other.promise0));
+    Construct(&promise1, std::move(other.promise1));
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION ~JoinState() {
     if (ready.is_set(0)) {
@@ -180,23 +172,11 @@ struct JoinState<Traits, P0, P1, P2> {
   }
   JoinState& operator=(const JoinState& other) = delete;
   JoinState& operator=(JoinState&& other) = delete;
-  GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION JoinState(JoinState&& other) noexcept
-      : ready(other.ready) {
-    if (ready.is_set(0)) {
-      Construct(&result0, std::move(other.result0));
-    } else {
-      Construct(&promise0, std::move(other.promise0));
-    }
-    if (ready.is_set(1)) {
-      Construct(&result1, std::move(other.result1));
-    } else {
-      Construct(&promise1, std::move(other.promise1));
-    }
-    if (ready.is_set(2)) {
-      Construct(&result2, std::move(other.result2));
-    } else {
-      Construct(&promise2, std::move(other.promise2));
-    }
+  GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION JoinState(JoinState&& other) noexcept {
+    DCHECK(other.ready.none());
+    Construct(&promise0, std::move(other.promise0));
+    Construct(&promise1, std::move(other.promise1));
+    Construct(&promise2, std::move(other.promise2));
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION ~JoinState() {
     if (ready.is_set(0)) {
@@ -337,28 +317,12 @@ struct JoinState<Traits, P0, P1, P2, P3> {
   }
   JoinState& operator=(const JoinState& other) = delete;
   JoinState& operator=(JoinState&& other) = delete;
-  GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION JoinState(JoinState&& other) noexcept
-      : ready(other.ready) {
-    if (ready.is_set(0)) {
-      Construct(&result0, std::move(other.result0));
-    } else {
-      Construct(&promise0, std::move(other.promise0));
-    }
-    if (ready.is_set(1)) {
-      Construct(&result1, std::move(other.result1));
-    } else {
-      Construct(&promise1, std::move(other.promise1));
-    }
-    if (ready.is_set(2)) {
-      Construct(&result2, std::move(other.result2));
-    } else {
-      Construct(&promise2, std::move(other.promise2));
-    }
-    if (ready.is_set(3)) {
-      Construct(&result3, std::move(other.result3));
-    } else {
-      Construct(&promise3, std::move(other.promise3));
-    }
+  GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION JoinState(JoinState&& other) noexcept {
+    DCHECK(other.ready.none());
+    Construct(&promise0, std::move(other.promise0));
+    Construct(&promise1, std::move(other.promise1));
+    Construct(&promise2, std::move(other.promise2));
+    Construct(&promise3, std::move(other.promise3));
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION ~JoinState() {
     if (ready.is_set(0)) {
@@ -535,33 +499,13 @@ struct JoinState<Traits, P0, P1, P2, P3, P4> {
   }
   JoinState& operator=(const JoinState& other) = delete;
   JoinState& operator=(JoinState&& other) = delete;
-  GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION JoinState(JoinState&& other) noexcept
-      : ready(other.ready) {
-    if (ready.is_set(0)) {
-      Construct(&result0, std::move(other.result0));
-    } else {
-      Construct(&promise0, std::move(other.promise0));
-    }
-    if (ready.is_set(1)) {
-      Construct(&result1, std::move(other.result1));
-    } else {
-      Construct(&promise1, std::move(other.promise1));
-    }
-    if (ready.is_set(2)) {
-      Construct(&result2, std::move(other.result2));
-    } else {
-      Construct(&promise2, std::move(other.promise2));
-    }
-    if (ready.is_set(3)) {
-      Construct(&result3, std::move(other.result3));
-    } else {
-      Construct(&promise3, std::move(other.promise3));
-    }
-    if (ready.is_set(4)) {
-      Construct(&result4, std::move(other.result4));
-    } else {
-      Construct(&promise4, std::move(other.promise4));
-    }
+  GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION JoinState(JoinState&& other) noexcept {
+    DCHECK(other.ready.none());
+    Construct(&promise0, std::move(other.promise0));
+    Construct(&promise1, std::move(other.promise1));
+    Construct(&promise2, std::move(other.promise2));
+    Construct(&promise3, std::move(other.promise3));
+    Construct(&promise4, std::move(other.promise4));
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION ~JoinState() {
     if (ready.is_set(0)) {
@@ -774,38 +718,14 @@ struct JoinState<Traits, P0, P1, P2, P3, P4, P5> {
   }
   JoinState& operator=(const JoinState& other) = delete;
   JoinState& operator=(JoinState&& other) = delete;
-  GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION JoinState(JoinState&& other) noexcept
-      : ready(other.ready) {
-    if (ready.is_set(0)) {
-      Construct(&result0, std::move(other.result0));
-    } else {
-      Construct(&promise0, std::move(other.promise0));
-    }
-    if (ready.is_set(1)) {
-      Construct(&result1, std::move(other.result1));
-    } else {
-      Construct(&promise1, std::move(other.promise1));
-    }
-    if (ready.is_set(2)) {
-      Construct(&result2, std::move(other.result2));
-    } else {
-      Construct(&promise2, std::move(other.promise2));
-    }
-    if (ready.is_set(3)) {
-      Construct(&result3, std::move(other.result3));
-    } else {
-      Construct(&promise3, std::move(other.promise3));
-    }
-    if (ready.is_set(4)) {
-      Construct(&result4, std::move(other.result4));
-    } else {
-      Construct(&promise4, std::move(other.promise4));
-    }
-    if (ready.is_set(5)) {
-      Construct(&result5, std::move(other.result5));
-    } else {
-      Construct(&promise5, std::move(other.promise5));
-    }
+  GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION JoinState(JoinState&& other) noexcept {
+    DCHECK(other.ready.none());
+    Construct(&promise0, std::move(other.promise0));
+    Construct(&promise1, std::move(other.promise1));
+    Construct(&promise2, std::move(other.promise2));
+    Construct(&promise3, std::move(other.promise3));
+    Construct(&promise4, std::move(other.promise4));
+    Construct(&promise5, std::move(other.promise5));
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION ~JoinState() {
     if (ready.is_set(0)) {
@@ -1054,43 +974,15 @@ struct JoinState<Traits, P0, P1, P2, P3, P4, P5, P6> {
   }
   JoinState& operator=(const JoinState& other) = delete;
   JoinState& operator=(JoinState&& other) = delete;
-  GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION JoinState(JoinState&& other) noexcept
-      : ready(other.ready) {
-    if (ready.is_set(0)) {
-      Construct(&result0, std::move(other.result0));
-    } else {
-      Construct(&promise0, std::move(other.promise0));
-    }
-    if (ready.is_set(1)) {
-      Construct(&result1, std::move(other.result1));
-    } else {
-      Construct(&promise1, std::move(other.promise1));
-    }
-    if (ready.is_set(2)) {
-      Construct(&result2, std::move(other.result2));
-    } else {
-      Construct(&promise2, std::move(other.promise2));
-    }
-    if (ready.is_set(3)) {
-      Construct(&result3, std::move(other.result3));
-    } else {
-      Construct(&promise3, std::move(other.promise3));
-    }
-    if (ready.is_set(4)) {
-      Construct(&result4, std::move(other.result4));
-    } else {
-      Construct(&promise4, std::move(other.promise4));
-    }
-    if (ready.is_set(5)) {
-      Construct(&result5, std::move(other.result5));
-    } else {
-      Construct(&promise5, std::move(other.promise5));
-    }
-    if (ready.is_set(6)) {
-      Construct(&result6, std::move(other.result6));
-    } else {
-      Construct(&promise6, std::move(other.promise6));
-    }
+  GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION JoinState(JoinState&& other) noexcept {
+    DCHECK(other.ready.none());
+    Construct(&promise0, std::move(other.promise0));
+    Construct(&promise1, std::move(other.promise1));
+    Construct(&promise2, std::move(other.promise2));
+    Construct(&promise3, std::move(other.promise3));
+    Construct(&promise4, std::move(other.promise4));
+    Construct(&promise5, std::move(other.promise5));
+    Construct(&promise6, std::move(other.promise6));
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION ~JoinState() {
     if (ready.is_set(0)) {
@@ -1375,48 +1267,16 @@ struct JoinState<Traits, P0, P1, P2, P3, P4, P5, P6, P7> {
   }
   JoinState& operator=(const JoinState& other) = delete;
   JoinState& operator=(JoinState&& other) = delete;
-  GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION JoinState(JoinState&& other) noexcept
-      : ready(other.ready) {
-    if (ready.is_set(0)) {
-      Construct(&result0, std::move(other.result0));
-    } else {
-      Construct(&promise0, std::move(other.promise0));
-    }
-    if (ready.is_set(1)) {
-      Construct(&result1, std::move(other.result1));
-    } else {
-      Construct(&promise1, std::move(other.promise1));
-    }
-    if (ready.is_set(2)) {
-      Construct(&result2, std::move(other.result2));
-    } else {
-      Construct(&promise2, std::move(other.promise2));
-    }
-    if (ready.is_set(3)) {
-      Construct(&result3, std::move(other.result3));
-    } else {
-      Construct(&promise3, std::move(other.promise3));
-    }
-    if (ready.is_set(4)) {
-      Construct(&result4, std::move(other.result4));
-    } else {
-      Construct(&promise4, std::move(other.promise4));
-    }
-    if (ready.is_set(5)) {
-      Construct(&result5, std::move(other.result5));
-    } else {
-      Construct(&promise5, std::move(other.promise5));
-    }
-    if (ready.is_set(6)) {
-      Construct(&result6, std::move(other.result6));
-    } else {
-      Construct(&promise6, std::move(other.promise6));
-    }
-    if (ready.is_set(7)) {
-      Construct(&result7, std::move(other.result7));
-    } else {
-      Construct(&promise7, std::move(other.promise7));
-    }
+  GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION JoinState(JoinState&& other) noexcept {
+    DCHECK(other.ready.none());
+    Construct(&promise0, std::move(other.promise0));
+    Construct(&promise1, std::move(other.promise1));
+    Construct(&promise2, std::move(other.promise2));
+    Construct(&promise3, std::move(other.promise3));
+    Construct(&promise4, std::move(other.promise4));
+    Construct(&promise5, std::move(other.promise5));
+    Construct(&promise6, std::move(other.promise6));
+    Construct(&promise7, std::move(other.promise7));
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION ~JoinState() {
     if (ready.is_set(0)) {
@@ -1736,53 +1596,17 @@ struct JoinState<Traits, P0, P1, P2, P3, P4, P5, P6, P7, P8> {
   }
   JoinState& operator=(const JoinState& other) = delete;
   JoinState& operator=(JoinState&& other) = delete;
-  GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION JoinState(JoinState&& other) noexcept
-      : ready(other.ready) {
-    if (ready.is_set(0)) {
-      Construct(&result0, std::move(other.result0));
-    } else {
-      Construct(&promise0, std::move(other.promise0));
-    }
-    if (ready.is_set(1)) {
-      Construct(&result1, std::move(other.result1));
-    } else {
-      Construct(&promise1, std::move(other.promise1));
-    }
-    if (ready.is_set(2)) {
-      Construct(&result2, std::move(other.result2));
-    } else {
-      Construct(&promise2, std::move(other.promise2));
-    }
-    if (ready.is_set(3)) {
-      Construct(&result3, std::move(other.result3));
-    } else {
-      Construct(&promise3, std::move(other.promise3));
-    }
-    if (ready.is_set(4)) {
-      Construct(&result4, std::move(other.result4));
-    } else {
-      Construct(&promise4, std::move(other.promise4));
-    }
-    if (ready.is_set(5)) {
-      Construct(&result5, std::move(other.result5));
-    } else {
-      Construct(&promise5, std::move(other.promise5));
-    }
-    if (ready.is_set(6)) {
-      Construct(&result6, std::move(other.result6));
-    } else {
-      Construct(&promise6, std::move(other.promise6));
-    }
-    if (ready.is_set(7)) {
-      Construct(&result7, std::move(other.result7));
-    } else {
-      Construct(&promise7, std::move(other.promise7));
-    }
-    if (ready.is_set(8)) {
-      Construct(&result8, std::move(other.result8));
-    } else {
-      Construct(&promise8, std::move(other.promise8));
-    }
+  GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION JoinState(JoinState&& other) noexcept {
+    DCHECK(other.ready.none());
+    Construct(&promise0, std::move(other.promise0));
+    Construct(&promise1, std::move(other.promise1));
+    Construct(&promise2, std::move(other.promise2));
+    Construct(&promise3, std::move(other.promise3));
+    Construct(&promise4, std::move(other.promise4));
+    Construct(&promise5, std::move(other.promise5));
+    Construct(&promise6, std::move(other.promise6));
+    Construct(&promise7, std::move(other.promise7));
+    Construct(&promise8, std::move(other.promise8));
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION ~JoinState() {
     if (ready.is_set(0)) {
diff --git a/src/core/lib/promise/detail/seq_state.h b/src/core/lib/promise/detail/seq_state.h
index a4dac2445b9..b2b635f98bc 100644
--- a/src/core/lib/promise/detail/seq_state.h
+++ b/src/core/lib/promise/detail/seq_state.h
@@ -122,23 +122,15 @@ struct SeqState<Traits, P, F0> {
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState(const SeqState& other) noexcept
       : state(other.state), whence(other.whence) {
-    CHECK(state == State::kState0);
+    DCHECK(state == State::kState0);
     Construct(&prior.current_promise, other.prior.current_promise);
     Construct(&prior.next_factory, other.prior.next_factory);
   }
   SeqState& operator=(const SeqState& other) = delete;
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState(SeqState&& other) noexcept
       : state(other.state), whence(other.whence) {
-    switch (state) {
-      case State::kState0:
-        Construct(&prior.current_promise,
-                  std::move(other.prior.current_promise));
-        goto tail0;
-      case State::kState1:
-        Construct(&current_promise, std::move(other.current_promise));
-        return;
-    }
-  tail0:
+    DCHECK(state == State::kState0);
+    Construct(&prior.current_promise, std::move(other.prior.current_promise));
     Construct(&prior.next_factory, std::move(other.prior.next_factory));
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState& operator=(SeqState&& other) =
@@ -259,31 +251,19 @@ struct SeqState<Traits, P, F0, F1> {
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState(const SeqState& other) noexcept
       : state(other.state), whence(other.whence) {
-    CHECK(state == State::kState0);
-    Construct(&prior.current_promise, other.prior.current_promise);
+    DCHECK(state == State::kState0);
+    Construct(&prior.prior.current_promise, other.prior.prior.current_promise);
     Construct(&prior.prior.next_factory, other.prior.prior.next_factory);
     Construct(&prior.next_factory, other.prior.next_factory);
   }
   SeqState& operator=(const SeqState& other) = delete;
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState(SeqState&& other) noexcept
       : state(other.state), whence(other.whence) {
-    switch (state) {
-      case State::kState0:
-        Construct(&prior.prior.current_promise,
-                  std::move(other.prior.prior.current_promise));
-        goto tail0;
-      case State::kState1:
-        Construct(&prior.current_promise,
-                  std::move(other.prior.current_promise));
-        goto tail1;
-      case State::kState2:
-        Construct(&current_promise, std::move(other.current_promise));
-        return;
-    }
-  tail0:
+    DCHECK(state == State::kState0);
+    Construct(&prior.prior.current_promise,
+              std::move(other.prior.prior.current_promise));
     Construct(&prior.prior.next_factory,
               std::move(other.prior.prior.next_factory));
-  tail1:
     Construct(&prior.next_factory, std::move(other.prior.next_factory));
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState& operator=(SeqState&& other) =
@@ -455,8 +435,9 @@ struct SeqState<Traits, P, F0, F1, F2> {
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState(const SeqState& other) noexcept
       : state(other.state), whence(other.whence) {
-    CHECK(state == State::kState0);
-    Construct(&prior.current_promise, other.prior.current_promise);
+    DCHECK(state == State::kState0);
+    Construct(&prior.prior.prior.current_promise,
+              other.prior.prior.prior.current_promise);
     Construct(&prior.prior.prior.next_factory,
               other.prior.prior.prior.next_factory);
     Construct(&prior.prior.next_factory, other.prior.prior.next_factory);
@@ -465,30 +446,13 @@ struct SeqState<Traits, P, F0, F1, F2> {
   SeqState& operator=(const SeqState& other) = delete;
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState(SeqState&& other) noexcept
       : state(other.state), whence(other.whence) {
-    switch (state) {
-      case State::kState0:
-        Construct(&prior.prior.prior.current_promise,
-                  std::move(other.prior.prior.prior.current_promise));
-        goto tail0;
-      case State::kState1:
-        Construct(&prior.prior.current_promise,
-                  std::move(other.prior.prior.current_promise));
-        goto tail1;
-      case State::kState2:
-        Construct(&prior.current_promise,
-                  std::move(other.prior.current_promise));
-        goto tail2;
-      case State::kState3:
-        Construct(&current_promise, std::move(other.current_promise));
-        return;
-    }
-  tail0:
+    DCHECK(state == State::kState0);
+    Construct(&prior.prior.prior.current_promise,
+              std::move(other.prior.prior.prior.current_promise));
     Construct(&prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.next_factory));
-  tail1:
     Construct(&prior.prior.next_factory,
               std::move(other.prior.prior.next_factory));
-  tail2:
     Construct(&prior.next_factory, std::move(other.prior.next_factory));
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState& operator=(SeqState&& other) =
@@ -710,8 +674,9 @@ struct SeqState<Traits, P, F0, F1, F2, F3> {
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState(const SeqState& other) noexcept
       : state(other.state), whence(other.whence) {
-    CHECK(state == State::kState0);
-    Construct(&prior.current_promise, other.prior.current_promise);
+    DCHECK(state == State::kState0);
+    Construct(&prior.prior.prior.prior.current_promise,
+              other.prior.prior.prior.prior.current_promise);
     Construct(&prior.prior.prior.prior.next_factory,
               other.prior.prior.prior.prior.next_factory);
     Construct(&prior.prior.prior.next_factory,
@@ -722,37 +687,15 @@ struct SeqState<Traits, P, F0, F1, F2, F3> {
   SeqState& operator=(const SeqState& other) = delete;
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState(SeqState&& other) noexcept
       : state(other.state), whence(other.whence) {
-    switch (state) {
-      case State::kState0:
-        Construct(&prior.prior.prior.prior.current_promise,
-                  std::move(other.prior.prior.prior.prior.current_promise));
-        goto tail0;
-      case State::kState1:
-        Construct(&prior.prior.prior.current_promise,
-                  std::move(other.prior.prior.prior.current_promise));
-        goto tail1;
-      case State::kState2:
-        Construct(&prior.prior.current_promise,
-                  std::move(other.prior.prior.current_promise));
-        goto tail2;
-      case State::kState3:
-        Construct(&prior.current_promise,
-                  std::move(other.prior.current_promise));
-        goto tail3;
-      case State::kState4:
-        Construct(&current_promise, std::move(other.current_promise));
-        return;
-    }
-  tail0:
+    DCHECK(state == State::kState0);
+    Construct(&prior.prior.prior.prior.current_promise,
+              std::move(other.prior.prior.prior.prior.current_promise));
     Construct(&prior.prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.prior.next_factory));
-  tail1:
     Construct(&prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.next_factory));
-  tail2:
     Construct(&prior.prior.next_factory,
               std::move(other.prior.prior.next_factory));
-  tail3:
     Construct(&prior.next_factory, std::move(other.prior.next_factory));
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState& operator=(SeqState&& other) =
@@ -1033,8 +976,9 @@ struct SeqState<Traits, P, F0, F1, F2, F3, F4> {
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState(const SeqState& other) noexcept
       : state(other.state), whence(other.whence) {
-    CHECK(state == State::kState0);
-    Construct(&prior.current_promise, other.prior.current_promise);
+    DCHECK(state == State::kState0);
+    Construct(&prior.prior.prior.prior.prior.current_promise,
+              other.prior.prior.prior.prior.prior.current_promise);
     Construct(&prior.prior.prior.prior.prior.next_factory,
               other.prior.prior.prior.prior.prior.next_factory);
     Construct(&prior.prior.prior.prior.next_factory,
@@ -1047,45 +991,17 @@ struct SeqState<Traits, P, F0, F1, F2, F3, F4> {
   SeqState& operator=(const SeqState& other) = delete;
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState(SeqState&& other) noexcept
       : state(other.state), whence(other.whence) {
-    switch (state) {
-      case State::kState0:
-        Construct(
-            &prior.prior.prior.prior.prior.current_promise,
-            std::move(other.prior.prior.prior.prior.prior.current_promise));
-        goto tail0;
-      case State::kState1:
-        Construct(&prior.prior.prior.prior.current_promise,
-                  std::move(other.prior.prior.prior.prior.current_promise));
-        goto tail1;
-      case State::kState2:
-        Construct(&prior.prior.prior.current_promise,
-                  std::move(other.prior.prior.prior.current_promise));
-        goto tail2;
-      case State::kState3:
-        Construct(&prior.prior.current_promise,
-                  std::move(other.prior.prior.current_promise));
-        goto tail3;
-      case State::kState4:
-        Construct(&prior.current_promise,
-                  std::move(other.prior.current_promise));
-        goto tail4;
-      case State::kState5:
-        Construct(&current_promise, std::move(other.current_promise));
-        return;
-    }
-  tail0:
+    DCHECK(state == State::kState0);
+    Construct(&prior.prior.prior.prior.prior.current_promise,
+              std::move(other.prior.prior.prior.prior.prior.current_promise));
     Construct(&prior.prior.prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.prior.prior.next_factory));
-  tail1:
     Construct(&prior.prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.prior.next_factory));
-  tail2:
     Construct(&prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.next_factory));
-  tail3:
     Construct(&prior.prior.next_factory,
               std::move(other.prior.prior.next_factory));
-  tail4:
     Construct(&prior.next_factory, std::move(other.prior.next_factory));
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState& operator=(SeqState&& other) =
@@ -1420,8 +1336,9 @@ struct SeqState<Traits, P, F0, F1, F2, F3, F4, F5> {
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState(const SeqState& other) noexcept
       : state(other.state), whence(other.whence) {
-    CHECK(state == State::kState0);
-    Construct(&prior.current_promise, other.prior.current_promise);
+    DCHECK(state == State::kState0);
+    Construct(&prior.prior.prior.prior.prior.prior.current_promise,
+              other.prior.prior.prior.prior.prior.prior.current_promise);
     Construct(&prior.prior.prior.prior.prior.prior.next_factory,
               other.prior.prior.prior.prior.prior.prior.next_factory);
     Construct(&prior.prior.prior.prior.prior.next_factory,
@@ -1436,55 +1353,21 @@ struct SeqState<Traits, P, F0, F1, F2, F3, F4, F5> {
   SeqState& operator=(const SeqState& other) = delete;
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState(SeqState&& other) noexcept
       : state(other.state), whence(other.whence) {
-    switch (state) {
-      case State::kState0:
-        Construct(
-            &prior.prior.prior.prior.prior.prior.current_promise,
-            std::move(
-                other.prior.prior.prior.prior.prior.prior.current_promise));
-        goto tail0;
-      case State::kState1:
-        Construct(
-            &prior.prior.prior.prior.prior.current_promise,
-            std::move(other.prior.prior.prior.prior.prior.current_promise));
-        goto tail1;
-      case State::kState2:
-        Construct(&prior.prior.prior.prior.current_promise,
-                  std::move(other.prior.prior.prior.prior.current_promise));
-        goto tail2;
-      case State::kState3:
-        Construct(&prior.prior.prior.current_promise,
-                  std::move(other.prior.prior.prior.current_promise));
-        goto tail3;
-      case State::kState4:
-        Construct(&prior.prior.current_promise,
-                  std::move(other.prior.prior.current_promise));
-        goto tail4;
-      case State::kState5:
-        Construct(&prior.current_promise,
-                  std::move(other.prior.current_promise));
-        goto tail5;
-      case State::kState6:
-        Construct(&current_promise, std::move(other.current_promise));
-        return;
-    }
-  tail0:
+    DCHECK(state == State::kState0);
+    Construct(
+        &prior.prior.prior.prior.prior.prior.current_promise,
+        std::move(other.prior.prior.prior.prior.prior.prior.current_promise));
     Construct(
         &prior.prior.prior.prior.prior.prior.next_factory,
         std::move(other.prior.prior.prior.prior.prior.prior.next_factory));
-  tail1:
     Construct(&prior.prior.prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.prior.prior.next_factory));
-  tail2:
     Construct(&prior.prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.prior.next_factory));
-  tail3:
     Construct(&prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.next_factory));
-  tail4:
     Construct(&prior.prior.next_factory,
               std::move(other.prior.prior.next_factory));
-  tail5:
     Construct(&prior.next_factory, std::move(other.prior.next_factory));
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState& operator=(SeqState&& other) =
@@ -1873,8 +1756,9 @@ struct SeqState<Traits, P, F0, F1, F2, F3, F4, F5, F6> {
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState(const SeqState& other) noexcept
       : state(other.state), whence(other.whence) {
-    CHECK(state == State::kState0);
-    Construct(&prior.current_promise, other.prior.current_promise);
+    DCHECK(state == State::kState0);
+    Construct(&prior.prior.prior.prior.prior.prior.prior.current_promise,
+              other.prior.prior.prior.prior.prior.prior.prior.current_promise);
     Construct(&prior.prior.prior.prior.prior.prior.prior.next_factory,
               other.prior.prior.prior.prior.prior.prior.prior.next_factory);
     Construct(&prior.prior.prior.prior.prior.prior.next_factory,
@@ -1891,65 +1775,26 @@ struct SeqState<Traits, P, F0, F1, F2, F3, F4, F5, F6> {
   SeqState& operator=(const SeqState& other) = delete;
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState(SeqState&& other) noexcept
       : state(other.state), whence(other.whence) {
-    switch (state) {
-      case State::kState0:
-        Construct(&prior.prior.prior.prior.prior.prior.prior.current_promise,
-                  std::move(other.prior.prior.prior.prior.prior.prior.prior
-                                .current_promise));
-        goto tail0;
-      case State::kState1:
-        Construct(
-            &prior.prior.prior.prior.prior.prior.current_promise,
-            std::move(
-                other.prior.prior.prior.prior.prior.prior.current_promise));
-        goto tail1;
-      case State::kState2:
-        Construct(
-            &prior.prior.prior.prior.prior.current_promise,
-            std::move(other.prior.prior.prior.prior.prior.current_promise));
-        goto tail2;
-      case State::kState3:
-        Construct(&prior.prior.prior.prior.current_promise,
-                  std::move(other.prior.prior.prior.prior.current_promise));
-        goto tail3;
-      case State::kState4:
-        Construct(&prior.prior.prior.current_promise,
-                  std::move(other.prior.prior.prior.current_promise));
-        goto tail4;
-      case State::kState5:
-        Construct(&prior.prior.current_promise,
-                  std::move(other.prior.prior.current_promise));
-        goto tail5;
-      case State::kState6:
-        Construct(&prior.current_promise,
-                  std::move(other.prior.current_promise));
-        goto tail6;
-      case State::kState7:
-        Construct(&current_promise, std::move(other.current_promise));
-        return;
-    }
-  tail0:
+    DCHECK(state == State::kState0);
+    Construct(
+        &prior.prior.prior.prior.prior.prior.prior.current_promise,
+        std::move(
+            other.prior.prior.prior.prior.prior.prior.prior.current_promise));
     Construct(
         &prior.prior.prior.prior.prior.prior.prior.next_factory,
         std::move(
             other.prior.prior.prior.prior.prior.prior.prior.next_factory));
-  tail1:
     Construct(
         &prior.prior.prior.prior.prior.prior.next_factory,
         std::move(other.prior.prior.prior.prior.prior.prior.next_factory));
-  tail2:
     Construct(&prior.prior.prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.prior.prior.next_factory));
-  tail3:
     Construct(&prior.prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.prior.next_factory));
-  tail4:
     Construct(&prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.next_factory));
-  tail5:
     Construct(&prior.prior.next_factory,
               std::move(other.prior.prior.next_factory));
-  tail6:
     Construct(&prior.next_factory, std::move(other.prior.next_factory));
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState& operator=(SeqState&& other) =
@@ -2394,8 +2239,10 @@ struct SeqState<Traits, P, F0, F1, F2, F3, F4, F5, F6, F7> {
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState(const SeqState& other) noexcept
       : state(other.state), whence(other.whence) {
-    CHECK(state == State::kState0);
-    Construct(&prior.current_promise, other.prior.current_promise);
+    DCHECK(state == State::kState0);
+    Construct(
+        &prior.prior.prior.prior.prior.prior.prior.prior.current_promise,
+        other.prior.prior.prior.prior.prior.prior.prior.prior.current_promise);
     Construct(
         &prior.prior.prior.prior.prior.prior.prior.prior.next_factory,
         other.prior.prior.prior.prior.prior.prior.prior.prior.next_factory);
@@ -2415,75 +2262,28 @@ struct SeqState<Traits, P, F0, F1, F2, F3, F4, F5, F6, F7> {
   SeqState& operator=(const SeqState& other) = delete;
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState(SeqState&& other) noexcept
       : state(other.state), whence(other.whence) {
-    switch (state) {
-      case State::kState0:
-        Construct(
-            &prior.prior.prior.prior.prior.prior.prior.prior.current_promise,
-            std::move(other.prior.prior.prior.prior.prior.prior.prior.prior
-                          .current_promise));
-        goto tail0;
-      case State::kState1:
-        Construct(&prior.prior.prior.prior.prior.prior.prior.current_promise,
-                  std::move(other.prior.prior.prior.prior.prior.prior.prior
-                                .current_promise));
-        goto tail1;
-      case State::kState2:
-        Construct(
-            &prior.prior.prior.prior.prior.prior.current_promise,
-            std::move(
-                other.prior.prior.prior.prior.prior.prior.current_promise));
-        goto tail2;
-      case State::kState3:
-        Construct(
-            &prior.prior.prior.prior.prior.current_promise,
-            std::move(other.prior.prior.prior.prior.prior.current_promise));
-        goto tail3;
-      case State::kState4:
-        Construct(&prior.prior.prior.prior.current_promise,
-                  std::move(other.prior.prior.prior.prior.current_promise));
-        goto tail4;
-      case State::kState5:
-        Construct(&prior.prior.prior.current_promise,
-                  std::move(other.prior.prior.prior.current_promise));
-        goto tail5;
-      case State::kState6:
-        Construct(&prior.prior.current_promise,
-                  std::move(other.prior.prior.current_promise));
-        goto tail6;
-      case State::kState7:
-        Construct(&prior.current_promise,
-                  std::move(other.prior.current_promise));
-        goto tail7;
-      case State::kState8:
-        Construct(&current_promise, std::move(other.current_promise));
-        return;
-    }
-  tail0:
+    DCHECK(state == State::kState0);
+    Construct(&prior.prior.prior.prior.prior.prior.prior.prior.current_promise,
+              std::move(other.prior.prior.prior.prior.prior.prior.prior.prior
+                            .current_promise));
     Construct(&prior.prior.prior.prior.prior.prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.prior.prior.prior.prior.prior
                             .next_factory));
-  tail1:
     Construct(
         &prior.prior.prior.prior.prior.prior.prior.next_factory,
         std::move(
             other.prior.prior.prior.prior.prior.prior.prior.next_factory));
-  tail2:
     Construct(
         &prior.prior.prior.prior.prior.prior.next_factory,
         std::move(other.prior.prior.prior.prior.prior.prior.next_factory));
-  tail3:
     Construct(&prior.prior.prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.prior.prior.next_factory));
-  tail4:
     Construct(&prior.prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.prior.next_factory));
-  tail5:
     Construct(&prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.next_factory));
-  tail6:
     Construct(&prior.prior.next_factory,
               std::move(other.prior.prior.next_factory));
-  tail7:
     Construct(&prior.next_factory, std::move(other.prior.next_factory));
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState& operator=(SeqState&& other) =
@@ -2989,8 +2789,11 @@ struct SeqState<Traits, P, F0, F1, F2, F3, F4, F5, F6, F7, F8> {
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState(const SeqState& other) noexcept
       : state(other.state), whence(other.whence) {
-    CHECK(state == State::kState0);
-    Construct(&prior.current_promise, other.prior.current_promise);
+    DCHECK(state == State::kState0);
+    Construct(
+        &prior.prior.prior.prior.prior.prior.prior.prior.prior.current_promise,
+        other.prior.prior.prior.prior.prior.prior.prior.prior.prior
+            .current_promise);
     Construct(
         &prior.prior.prior.prior.prior.prior.prior.prior.prior.next_factory,
         other.prior.prior.prior.prior.prior.prior.prior.prior.prior
@@ -3014,86 +2817,33 @@ struct SeqState<Traits, P, F0, F1, F2, F3, F4, F5, F6, F7, F8> {
   SeqState& operator=(const SeqState& other) = delete;
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState(SeqState&& other) noexcept
       : state(other.state), whence(other.whence) {
-    switch (state) {
-      case State::kState0:
-        Construct(&prior.prior.prior.prior.prior.prior.prior.prior.prior
-                       .current_promise,
-                  std::move(other.prior.prior.prior.prior.prior.prior.prior
-                                .prior.prior.current_promise));
-        goto tail0;
-      case State::kState1:
-        Construct(
-            &prior.prior.prior.prior.prior.prior.prior.prior.current_promise,
-            std::move(other.prior.prior.prior.prior.prior.prior.prior.prior
-                          .current_promise));
-        goto tail1;
-      case State::kState2:
-        Construct(&prior.prior.prior.prior.prior.prior.prior.current_promise,
-                  std::move(other.prior.prior.prior.prior.prior.prior.prior
-                                .current_promise));
-        goto tail2;
-      case State::kState3:
-        Construct(
-            &prior.prior.prior.prior.prior.prior.current_promise,
-            std::move(
-                other.prior.prior.prior.prior.prior.prior.current_promise));
-        goto tail3;
-      case State::kState4:
-        Construct(
-            &prior.prior.prior.prior.prior.current_promise,
-            std::move(other.prior.prior.prior.prior.prior.current_promise));
-        goto tail4;
-      case State::kState5:
-        Construct(&prior.prior.prior.prior.current_promise,
-                  std::move(other.prior.prior.prior.prior.current_promise));
-        goto tail5;
-      case State::kState6:
-        Construct(&prior.prior.prior.current_promise,
-                  std::move(other.prior.prior.prior.current_promise));
-        goto tail6;
-      case State::kState7:
-        Construct(&prior.prior.current_promise,
-                  std::move(other.prior.prior.current_promise));
-        goto tail7;
-      case State::kState8:
-        Construct(&prior.current_promise,
-                  std::move(other.prior.current_promise));
-        goto tail8;
-      case State::kState9:
-        Construct(&current_promise, std::move(other.current_promise));
-        return;
-    }
-  tail0:
+    DCHECK(state == State::kState0);
+    Construct(
+        &prior.prior.prior.prior.prior.prior.prior.prior.prior.current_promise,
+        std::move(other.prior.prior.prior.prior.prior.prior.prior.prior.prior
+                      .current_promise));
     Construct(
         &prior.prior.prior.prior.prior.prior.prior.prior.prior.next_factory,
         std::move(other.prior.prior.prior.prior.prior.prior.prior.prior.prior
                       .next_factory));
-  tail1:
     Construct(&prior.prior.prior.prior.prior.prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.prior.prior.prior.prior.prior
                             .next_factory));
-  tail2:
     Construct(
         &prior.prior.prior.prior.prior.prior.prior.next_factory,
         std::move(
             other.prior.prior.prior.prior.prior.prior.prior.next_factory));
-  tail3:
     Construct(
         &prior.prior.prior.prior.prior.prior.next_factory,
         std::move(other.prior.prior.prior.prior.prior.prior.next_factory));
-  tail4:
     Construct(&prior.prior.prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.prior.prior.next_factory));
-  tail5:
     Construct(&prior.prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.prior.next_factory));
-  tail6:
     Construct(&prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.next_factory));
-  tail7:
     Construct(&prior.prior.next_factory,
               std::move(other.prior.prior.next_factory));
-  tail8:
     Construct(&prior.next_factory, std::move(other.prior.next_factory));
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState& operator=(SeqState&& other) =
@@ -3660,8 +3410,11 @@ struct SeqState<Traits, P, F0, F1, F2, F3, F4, F5, F6, F7, F8, F9> {
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState(const SeqState& other) noexcept
       : state(other.state), whence(other.whence) {
-    CHECK(state == State::kState0);
-    Construct(&prior.current_promise, other.prior.current_promise);
+    DCHECK(state == State::kState0);
+    Construct(&prior.prior.prior.prior.prior.prior.prior.prior.prior.prior
+                   .current_promise,
+              other.prior.prior.prior.prior.prior.prior.prior.prior.prior.prior
+                  .current_promise);
     Construct(&prior.prior.prior.prior.prior.prior.prior.prior.prior.prior
                    .next_factory,
               other.prior.prior.prior.prior.prior.prior.prior.prior.prior.prior
@@ -3689,97 +3442,37 @@ struct SeqState<Traits, P, F0, F1, F2, F3, F4, F5, F6, F7, F8, F9> {
   SeqState& operator=(const SeqState& other) = delete;
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState(SeqState&& other) noexcept
       : state(other.state), whence(other.whence) {
-    switch (state) {
-      case State::kState0:
-        Construct(&prior.prior.prior.prior.prior.prior.prior.prior.prior.prior
-                       .current_promise,
-                  std::move(other.prior.prior.prior.prior.prior.prior.prior
-                                .prior.prior.prior.current_promise));
-        goto tail0;
-      case State::kState1:
-        Construct(&prior.prior.prior.prior.prior.prior.prior.prior.prior
-                       .current_promise,
-                  std::move(other.prior.prior.prior.prior.prior.prior.prior
-                                .prior.prior.current_promise));
-        goto tail1;
-      case State::kState2:
-        Construct(
-            &prior.prior.prior.prior.prior.prior.prior.prior.current_promise,
-            std::move(other.prior.prior.prior.prior.prior.prior.prior.prior
-                          .current_promise));
-        goto tail2;
-      case State::kState3:
-        Construct(&prior.prior.prior.prior.prior.prior.prior.current_promise,
-                  std::move(other.prior.prior.prior.prior.prior.prior.prior
-                                .current_promise));
-        goto tail3;
-      case State::kState4:
-        Construct(
-            &prior.prior.prior.prior.prior.prior.current_promise,
-            std::move(
-                other.prior.prior.prior.prior.prior.prior.current_promise));
-        goto tail4;
-      case State::kState5:
-        Construct(
-            &prior.prior.prior.prior.prior.current_promise,
-            std::move(other.prior.prior.prior.prior.prior.current_promise));
-        goto tail5;
-      case State::kState6:
-        Construct(&prior.prior.prior.prior.current_promise,
-                  std::move(other.prior.prior.prior.prior.current_promise));
-        goto tail6;
-      case State::kState7:
-        Construct(&prior.prior.prior.current_promise,
-                  std::move(other.prior.prior.prior.current_promise));
-        goto tail7;
-      case State::kState8:
-        Construct(&prior.prior.current_promise,
-                  std::move(other.prior.prior.current_promise));
-        goto tail8;
-      case State::kState9:
-        Construct(&prior.current_promise,
-                  std::move(other.prior.current_promise));
-        goto tail9;
-      case State::kState10:
-        Construct(&current_promise, std::move(other.current_promise));
-        return;
-    }
-  tail0:
+    DCHECK(state == State::kState0);
+    Construct(&prior.prior.prior.prior.prior.prior.prior.prior.prior.prior
+                   .current_promise,
+              std::move(other.prior.prior.prior.prior.prior.prior.prior.prior
+                            .prior.prior.current_promise));
     Construct(&prior.prior.prior.prior.prior.prior.prior.prior.prior.prior
                    .next_factory,
               std::move(other.prior.prior.prior.prior.prior.prior.prior.prior
                             .prior.prior.next_factory));
-  tail1:
     Construct(
         &prior.prior.prior.prior.prior.prior.prior.prior.prior.next_factory,
         std::move(other.prior.prior.prior.prior.prior.prior.prior.prior.prior
                       .next_factory));
-  tail2:
     Construct(&prior.prior.prior.prior.prior.prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.prior.prior.prior.prior.prior
                             .next_factory));
-  tail3:
     Construct(
         &prior.prior.prior.prior.prior.prior.prior.next_factory,
         std::move(
             other.prior.prior.prior.prior.prior.prior.prior.next_factory));
-  tail4:
     Construct(
         &prior.prior.prior.prior.prior.prior.next_factory,
         std::move(other.prior.prior.prior.prior.prior.prior.next_factory));
-  tail5:
     Construct(&prior.prior.prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.prior.prior.next_factory));
-  tail6:
     Construct(&prior.prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.prior.next_factory));
-  tail7:
     Construct(&prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.next_factory));
-  tail8:
     Construct(&prior.prior.next_factory,
               std::move(other.prior.prior.next_factory));
-  tail9:
     Construct(&prior.next_factory, std::move(other.prior.next_factory));
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState& operator=(SeqState&& other) =
@@ -4408,8 +4101,11 @@ struct SeqState<Traits, P, F0, F1, F2, F3, F4, F5, F6, F7, F8, F9, F10> {
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState(const SeqState& other) noexcept
       : state(other.state), whence(other.whence) {
-    CHECK(state == State::kState0);
-    Construct(&prior.current_promise, other.prior.current_promise);
+    DCHECK(state == State::kState0);
+    Construct(&prior.prior.prior.prior.prior.prior.prior.prior.prior.prior.prior
+                   .current_promise,
+              other.prior.prior.prior.prior.prior.prior.prior.prior.prior.prior
+                  .prior.current_promise);
     Construct(&prior.prior.prior.prior.prior.prior.prior.prior.prior.prior.prior
                    .next_factory,
               other.prior.prior.prior.prior.prior.prior.prior.prior.prior.prior
@@ -4441,108 +4137,41 @@ struct SeqState<Traits, P, F0, F1, F2, F3, F4, F5, F6, F7, F8, F9, F10> {
   SeqState& operator=(const SeqState& other) = delete;
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState(SeqState&& other) noexcept
       : state(other.state), whence(other.whence) {
-    switch (state) {
-      case State::kState0:
-        Construct(&prior.prior.prior.prior.prior.prior.prior.prior.prior.prior
-                       .prior.current_promise,
-                  std::move(other.prior.prior.prior.prior.prior.prior.prior
-                                .prior.prior.prior.prior.current_promise));
-        goto tail0;
-      case State::kState1:
-        Construct(&prior.prior.prior.prior.prior.prior.prior.prior.prior.prior
-                       .current_promise,
-                  std::move(other.prior.prior.prior.prior.prior.prior.prior
-                                .prior.prior.prior.current_promise));
-        goto tail1;
-      case State::kState2:
-        Construct(&prior.prior.prior.prior.prior.prior.prior.prior.prior
-                       .current_promise,
-                  std::move(other.prior.prior.prior.prior.prior.prior.prior
-                                .prior.prior.current_promise));
-        goto tail2;
-      case State::kState3:
-        Construct(
-            &prior.prior.prior.prior.prior.prior.prior.prior.current_promise,
-            std::move(other.prior.prior.prior.prior.prior.prior.prior.prior
-                          .current_promise));
-        goto tail3;
-      case State::kState4:
-        Construct(&prior.prior.prior.prior.prior.prior.prior.current_promise,
-                  std::move(other.prior.prior.prior.prior.prior.prior.prior
-                                .current_promise));
-        goto tail4;
-      case State::kState5:
-        Construct(
-            &prior.prior.prior.prior.prior.prior.current_promise,
-            std::move(
-                other.prior.prior.prior.prior.prior.prior.current_promise));
-        goto tail5;
-      case State::kState6:
-        Construct(
-            &prior.prior.prior.prior.prior.current_promise,
-            std::move(other.prior.prior.prior.prior.prior.current_promise));
-        goto tail6;
-      case State::kState7:
-        Construct(&prior.prior.prior.prior.current_promise,
-                  std::move(other.prior.prior.prior.prior.current_promise));
-        goto tail7;
-      case State::kState8:
-        Construct(&prior.prior.prior.current_promise,
-                  std::move(other.prior.prior.prior.current_promise));
-        goto tail8;
-      case State::kState9:
-        Construct(&prior.prior.current_promise,
-                  std::move(other.prior.prior.current_promise));
-        goto tail9;
-      case State::kState10:
-        Construct(&prior.current_promise,
-                  std::move(other.prior.current_promise));
-        goto tail10;
-      case State::kState11:
-        Construct(&current_promise, std::move(other.current_promise));
-        return;
-    }
-  tail0:
+    DCHECK(state == State::kState0);
+    Construct(&prior.prior.prior.prior.prior.prior.prior.prior.prior.prior.prior
+                   .current_promise,
+              std::move(other.prior.prior.prior.prior.prior.prior.prior.prior
+                            .prior.prior.prior.current_promise));
     Construct(&prior.prior.prior.prior.prior.prior.prior.prior.prior.prior.prior
                    .next_factory,
               std::move(other.prior.prior.prior.prior.prior.prior.prior.prior
                             .prior.prior.prior.next_factory));
-  tail1:
     Construct(&prior.prior.prior.prior.prior.prior.prior.prior.prior.prior
                    .next_factory,
               std::move(other.prior.prior.prior.prior.prior.prior.prior.prior
                             .prior.prior.next_factory));
-  tail2:
     Construct(
         &prior.prior.prior.prior.prior.prior.prior.prior.prior.next_factory,
         std::move(other.prior.prior.prior.prior.prior.prior.prior.prior.prior
                       .next_factory));
-  tail3:
     Construct(&prior.prior.prior.prior.prior.prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.prior.prior.prior.prior.prior
                             .next_factory));
-  tail4:
     Construct(
         &prior.prior.prior.prior.prior.prior.prior.next_factory,
         std::move(
             other.prior.prior.prior.prior.prior.prior.prior.next_factory));
-  tail5:
     Construct(
         &prior.prior.prior.prior.prior.prior.next_factory,
         std::move(other.prior.prior.prior.prior.prior.prior.next_factory));
-  tail6:
     Construct(&prior.prior.prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.prior.prior.next_factory));
-  tail7:
     Construct(&prior.prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.prior.next_factory));
-  tail8:
     Construct(&prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.next_factory));
-  tail9:
     Construct(&prior.prior.next_factory,
               std::move(other.prior.prior.next_factory));
-  tail10:
     Construct(&prior.next_factory, std::move(other.prior.next_factory));
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState& operator=(SeqState&& other) =
@@ -5235,8 +4864,11 @@ struct SeqState<Traits, P, F0, F1, F2, F3, F4, F5, F6, F7, F8, F9, F10, F11> {
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState(const SeqState& other) noexcept
       : state(other.state), whence(other.whence) {
-    CHECK(state == State::kState0);
-    Construct(&prior.current_promise, other.prior.current_promise);
+    DCHECK(state == State::kState0);
+    Construct(&prior.prior.prior.prior.prior.prior.prior.prior.prior.prior.prior
+                   .prior.current_promise,
+              other.prior.prior.prior.prior.prior.prior.prior.prior.prior.prior
+                  .prior.prior.current_promise);
     Construct(&prior.prior.prior.prior.prior.prior.prior.prior.prior.prior.prior
                    .prior.next_factory,
               other.prior.prior.prior.prior.prior.prior.prior.prior.prior.prior
@@ -5272,120 +4904,45 @@ struct SeqState<Traits, P, F0, F1, F2, F3, F4, F5, F6, F7, F8, F9, F10, F11> {
   SeqState& operator=(const SeqState& other) = delete;
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState(SeqState&& other) noexcept
       : state(other.state), whence(other.whence) {
-    switch (state) {
-      case State::kState0:
-        Construct(
-            &prior.prior.prior.prior.prior.prior.prior.prior.prior.prior.prior
-                 .prior.current_promise,
-            std::move(other.prior.prior.prior.prior.prior.prior.prior.prior
-                          .prior.prior.prior.prior.current_promise));
-        goto tail0;
-      case State::kState1:
-        Construct(&prior.prior.prior.prior.prior.prior.prior.prior.prior.prior
-                       .prior.current_promise,
-                  std::move(other.prior.prior.prior.prior.prior.prior.prior
-                                .prior.prior.prior.prior.current_promise));
-        goto tail1;
-      case State::kState2:
-        Construct(&prior.prior.prior.prior.prior.prior.prior.prior.prior.prior
-                       .current_promise,
-                  std::move(other.prior.prior.prior.prior.prior.prior.prior
-                                .prior.prior.prior.current_promise));
-        goto tail2;
-      case State::kState3:
-        Construct(&prior.prior.prior.prior.prior.prior.prior.prior.prior
-                       .current_promise,
-                  std::move(other.prior.prior.prior.prior.prior.prior.prior
-                                .prior.prior.current_promise));
-        goto tail3;
-      case State::kState4:
-        Construct(
-            &prior.prior.prior.prior.prior.prior.prior.prior.current_promise,
-            std::move(other.prior.prior.prior.prior.prior.prior.prior.prior
-                          .current_promise));
-        goto tail4;
-      case State::kState5:
-        Construct(&prior.prior.prior.prior.prior.prior.prior.current_promise,
-                  std::move(other.prior.prior.prior.prior.prior.prior.prior
-                                .current_promise));
-        goto tail5;
-      case State::kState6:
-        Construct(
-            &prior.prior.prior.prior.prior.prior.current_promise,
-            std::move(
-                other.prior.prior.prior.prior.prior.prior.current_promise));
-        goto tail6;
-      case State::kState7:
-        Construct(
-            &prior.prior.prior.prior.prior.current_promise,
-            std::move(other.prior.prior.prior.prior.prior.current_promise));
-        goto tail7;
-      case State::kState8:
-        Construct(&prior.prior.prior.prior.current_promise,
-                  std::move(other.prior.prior.prior.prior.current_promise));
-        goto tail8;
-      case State::kState9:
-        Construct(&prior.prior.prior.current_promise,
-                  std::move(other.prior.prior.prior.current_promise));
-        goto tail9;
-      case State::kState10:
-        Construct(&prior.prior.current_promise,
-                  std::move(other.prior.prior.current_promise));
-        goto tail10;
-      case State::kState11:
-        Construct(&prior.current_promise,
-                  std::move(other.prior.current_promise));
-        goto tail11;
-      case State::kState12:
-        Construct(&current_promise, std::move(other.current_promise));
-        return;
-    }
-  tail0:
+    DCHECK(state == State::kState0);
+    Construct(&prior.prior.prior.prior.prior.prior.prior.prior.prior.prior.prior
+                   .prior.current_promise,
+              std::move(other.prior.prior.prior.prior.prior.prior.prior.prior
+                            .prior.prior.prior.prior.current_promise));
     Construct(&prior.prior.prior.prior.prior.prior.prior.prior.prior.prior.prior
                    .prior.next_factory,
               std::move(other.prior.prior.prior.prior.prior.prior.prior.prior
                             .prior.prior.prior.prior.next_factory));
-  tail1:
     Construct(&prior.prior.prior.prior.prior.prior.prior.prior.prior.prior.prior
                    .next_factory,
               std::move(other.prior.prior.prior.prior.prior.prior.prior.prior
                             .prior.prior.prior.next_factory));
-  tail2:
     Construct(&prior.prior.prior.prior.prior.prior.prior.prior.prior.prior
                    .next_factory,
               std::move(other.prior.prior.prior.prior.prior.prior.prior.prior
                             .prior.prior.next_factory));
-  tail3:
     Construct(
         &prior.prior.prior.prior.prior.prior.prior.prior.prior.next_factory,
         std::move(other.prior.prior.prior.prior.prior.prior.prior.prior.prior
                       .next_factory));
-  tail4:
     Construct(&prior.prior.prior.prior.prior.prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.prior.prior.prior.prior.prior
                             .next_factory));
-  tail5:
     Construct(
         &prior.prior.prior.prior.prior.prior.prior.next_factory,
         std::move(
             other.prior.prior.prior.prior.prior.prior.prior.next_factory));
-  tail6:
     Construct(
         &prior.prior.prior.prior.prior.prior.next_factory,
         std::move(other.prior.prior.prior.prior.prior.prior.next_factory));
-  tail7:
     Construct(&prior.prior.prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.prior.prior.next_factory));
-  tail8:
     Construct(&prior.prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.prior.next_factory));
-  tail9:
     Construct(&prior.prior.prior.next_factory,
               std::move(other.prior.prior.prior.next_factory));
-  tail10:
     Construct(&prior.prior.next_factory,
               std::move(other.prior.prior.next_factory));
-  tail11:
     Construct(&prior.next_factory, std::move(other.prior.next_factory));
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState& operator=(SeqState&& other) =
diff --git a/tools/codegen/core/gen_join.py b/tools/codegen/core/gen_join.py
index 418b7c87219..d0bd3434a07 100755
--- a/tools/codegen/core/gen_join.py
+++ b/tools/codegen/core/gen_join.py
@@ -46,13 +46,10 @@ struct JoinState<Traits, ${",".join(f"P{i}" for i in range(0,n))}> {
   }
   JoinState& operator=(const JoinState& other) = delete;
   JoinState& operator=(JoinState&& other) = delete;
-  GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION JoinState(JoinState&& other) noexcept : ready(other.ready) {
+  GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION JoinState(JoinState&& other) noexcept {
+    DCHECK(other.ready.none());
 % for i in range(0,n):
-    if (ready.is_set(${i})) {
-      Construct(&result${i}, std::move(other.result${i}));
-    } else {
-      Construct(&promise${i}, std::move(other.promise${i}));
-    }
+    Construct(&promise${i}, std::move(other.promise${i}));
 % endfor
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION ~JoinState() {
diff --git a/tools/codegen/core/gen_seq.py b/tools/codegen/core/gen_seq.py
index faa5b65a4eb..f537fd63f9c 100755
--- a/tools/codegen/core/gen_seq.py
+++ b/tools/codegen/core/gen_seq.py
@@ -110,9 +110,9 @@ tail${i}:
 % endfor
   }
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState(const SeqState& other) noexcept : state(other.state), whence(other.whence) {
-    CHECK(state == State::kState0);
-    Construct(&${"prior."*(n-1-i)}current_promise,
-            other.${"prior."*(n-1-i)}current_promise);
+    DCHECK(state == State::kState0);
+    Construct(&${"prior."*(n-1)}current_promise,
+            other.${"prior."*(n-1)}current_promise);
 % for i in range(0,n-1):
     Construct(&${"prior."*(n-1-i)}next_factory,
               other.${"prior."*(n-1-i)}next_factory);
@@ -120,19 +120,10 @@ tail${i}:
   }
   SeqState& operator=(const SeqState& other) = delete;
   GPR_ATTRIBUTE_ALWAYS_INLINE_FUNCTION SeqState(SeqState&& other) noexcept : state(other.state), whence(other.whence) {
-    switch (state) {
+    DCHECK(state == State::kState0);
+    Construct(&${"prior."*(n-1)}current_promise,
+              std::move(other.${"prior."*(n-1)}current_promise));
 % for i in range(0,n-1):
-     case State::kState${i}:
-      Construct(&${"prior."*(n-1-i)}current_promise,
-                std::move(other.${"prior."*(n-1-i)}current_promise));
-      goto tail${i};
-% endfor
-     case State::kState${n-1}:
-      Construct(&current_promise, std::move(other.current_promise));
-      return;
-    }
-% for i in range(0,n-1):
-tail${i}:
     Construct(&${"prior."*(n-1-i)}next_factory,
               std::move(other.${"prior."*(n-1-i)}next_factory));
 % endfor