Index: llvm/lib/Transforms/Coroutines/CoroFrame.cpp
===================================================================
--- llvm/lib/Transforms/Coroutines/CoroFrame.cpp
+++ llvm/lib/Transforms/Coroutines/CoroFrame.cpp
@@ -596,9 +596,21 @@
     // NonOverlappedAllocaSet.
     for (auto &AllocaSet : NonOverlapedAllocas) {
       assert(!AllocaSet.empty() && "Processing Alloca Set is not empty.\n");
-      bool CouldMerge = none_of(AllocaSet, [&](auto Iter) {
+      bool NoInference = none_of(AllocaSet, [&](auto Iter) {
         return IsAllocaInferenre(Alloca, Iter);
       });
+      // If the alignment of A is multiple of the alignment of B, the address
+      // of A should satisfy the requirement for aligning for B.
+      //
+      // There may be other more fine-grained strategies to handle the alignment
+      // infomation during the merging process. But it seems hard to handle
+      // these strategies and benefit little.
+      bool Alignable = [&]() -> bool {
+        auto *LargestAlloca = *AllocaSet.begin();
+        return LargestAlloca->getAlign().value() % Alloca->getAlign().value() ==
+               0;
+      }();
+      bool CouldMerge = NoInference && Alignable;
       if (!CouldMerge)
         continue;
       AllocaIndex[Alloca] = AllocaIndex[*AllocaSet.begin()];
@@ -1108,13 +1120,18 @@
 
     auto GEP = cast<GetElementPtrInst>(
         Builder.CreateInBoundsGEP(FrameTy, FramePtr, Indices));
-    if (isa<AllocaInst>(Orig)) {
+    if (auto *AI = dyn_cast<AllocaInst>(Orig)) {
       // If the type of GEP is not equal to the type of AllocaInst, it implies
       // that the AllocaInst may be reused in the Frame slot of other
-      // AllocaInst. So we cast the GEP to the type of AllocaInst.
-      if (GEP->getResultElementType() != Orig->getType())
-        return Builder.CreateBitCast(GEP, Orig->getType(),
-                                     Orig->getName() + Twine(".cast"));
+      // AllocaInst. So We cast GEP to the AllocaInst here to re-use
+      // the Frame storage.
+      //
+      // Note: If we change the strategy dealing with alignment, we need refine
+      // this casting.
+      if (GEP->getResultElementType() != AI->getType()) {
+        return Builder.CreateBitCast(GEP, AI->getType(),
+                                     AI->getName() + Twine(".cast"));
+      }
     }
     return GEP;
   };
Index: llvm/test/Transforms/Coroutines/coro-frame-reuse-alloca-04.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/Coroutines/coro-frame-reuse-alloca-04.ll
@@ -0,0 +1,80 @@
+; Tests that variables of different type with incompatible alignment in a Corotuine whose lifetime 
+; range is not overlapping each other should not re-use the same slot in Coroutine frame. 
+; RUN: opt < %s -coro-split -reuse-storage-in-coroutine-frame -S | FileCheck %s
+; RUN: opt < %s -passes=coro-split -reuse-storage-in-coroutine-frame -S | FileCheck %s
+%"struct.task::promise_type" = type { i8 }
+%struct.awaitable = type { i8 }
+%struct.big_structure = type { [500 x i8] }
+%struct.big_structure.2 = type { [300 x i8] }
+declare i8* @malloc(i64)
+declare void @consume(%struct.big_structure*)
+declare void @consume.2(%struct.big_structure.2*)
+define void @a(i1 zeroext %cond) "coroutine.presplit"="1" {
+entry:
+  %__promise = alloca %"struct.task::promise_type", align 1
+  %a = alloca %struct.big_structure, align 1
+  %ref.tmp7 = alloca %struct.awaitable, align 1
+  %b = alloca %struct.big_structure.2, align 32
+  %ref.tmp18 = alloca %struct.awaitable, align 1
+  %0 = getelementptr inbounds %"struct.task::promise_type", %"struct.task::promise_type"* %__promise, i64 0, i32 0
+  %1 = call token @llvm.coro.id(i32 16, i8* nonnull %0, i8* bitcast (void (i1)* @a to i8*), i8* null)
+  br label %init.ready
+init.ready:
+  %2 = call noalias nonnull i8* @llvm.coro.begin(token %1, i8* null)
+  call void @llvm.lifetime.start.p0i8(i64 1, i8* nonnull %0)
+  br i1 %cond, label %if.then, label %if.else
+if.then:
+  %3 = getelementptr inbounds %struct.big_structure, %struct.big_structure* %a, i64 0, i32 0, i64 0
+  call void @llvm.lifetime.start.p0i8(i64 500, i8* nonnull %3)
+  call void @consume(%struct.big_structure* nonnull %a)
+  %save = call token @llvm.coro.save(i8* null)
+  %suspend = call i8 @llvm.coro.suspend(token %save, i1 false)
+  switch i8 %suspend, label %coro.ret [
+    i8 0, label %await.ready
+    i8 1, label %cleanup1
+  ]
+await.ready:
+  call void @llvm.lifetime.end.p0i8(i64 500, i8* nonnull %3)
+  br label %cleanup1
+if.else:
+  %4 = getelementptr inbounds %struct.big_structure.2, %struct.big_structure.2* %b, i64 0, i32 0, i64 0
+  call void @llvm.lifetime.start.p0i8(i64 300, i8* nonnull %4)
+  call void @consume.2(%struct.big_structure.2* nonnull %b)
+  %save2 = call token @llvm.coro.save(i8* null)
+  %suspend2 = call i8 @llvm.coro.suspend(token %save2, i1 false)
+  switch i8 %suspend2, label %coro.ret [
+    i8 0, label %await2.ready
+    i8 1, label %cleanup2
+  ]
+await2.ready:
+  call void @llvm.lifetime.end.p0i8(i64 300, i8* nonnull %4)
+  br label %cleanup2
+cleanup1:
+  call void @llvm.lifetime.end.p0i8(i64 500, i8* nonnull %3)
+  br label %cleanup
+cleanup2:
+  call void @llvm.lifetime.end.p0i8(i64 300, i8* nonnull %4)
+  br label %cleanup
+cleanup:
+  call i8* @llvm.coro.free(token %1, i8* %2)
+  br label %coro.ret
+coro.ret:
+  call i1 @llvm.coro.end(i8* null, i1 false)
+  ret void
+}
+; CHECK:       %a.Frame = type { void (%a.Frame*)*, void (%a.Frame*)*, %"struct.task::promise_type", %struct.big_structure, i1, [26 x i8], %struct.big_structure.2 }
+; CHECK-LABEL: @a.resume(
+; CHECK:         %[[A:.*]] = getelementptr inbounds %a.Frame, %a.Frame* %FramePtr, i32 0, i32 3
+; CHECK:         %[[A:.*]] = getelementptr inbounds %a.Frame, %a.Frame* %FramePtr, i32 0, i32 6
+
+declare token @llvm.coro.id(i32, i8* readnone, i8* nocapture readonly, i8*)
+declare i1 @llvm.coro.alloc(token) #3
+declare i64 @llvm.coro.size.i64() #5
+declare i8* @llvm.coro.begin(token, i8* writeonly) #3
+declare token @llvm.coro.save(i8*) #3
+declare i8* @llvm.coro.frame() #5
+declare i8 @llvm.coro.suspend(token, i1) #3
+declare i8* @llvm.coro.free(token, i8* nocapture readonly) #2
+declare i1 @llvm.coro.end(i8*, i1) #3
+declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture) #4
+declare void @llvm.lifetime.end.p0i8(i64, i8* nocapture) #4
Index: llvm/test/Transforms/Coroutines/coro-frame-reuse-alloca-05.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/Coroutines/coro-frame-reuse-alloca-05.ll
@@ -0,0 +1,80 @@
+; Tests that variables of different type with incompatible alignment in a Corotuine whose 
+; lifetime range is not overlapping each other re-use the same slot in CorotuineFrame.
+; RUN: opt < %s -coro-split -reuse-storage-in-coroutine-frame -S | FileCheck %s
+; RUN: opt < %s -passes=coro-split -reuse-storage-in-coroutine-frame -S | FileCheck %s
+%"struct.task::promise_type" = type { i8 }
+%struct.awaitable = type { i8 }
+%struct.big_structure = type { [500 x i8] }
+%struct.big_structure.2 = type { [400 x i8] }
+declare i8* @malloc(i64)
+declare void @consume(%struct.big_structure*)
+declare void @consume.2(%struct.big_structure.2*)
+define void @a(i1 zeroext %cond) "coroutine.presplit"="1" {
+entry:
+  %__promise = alloca %"struct.task::promise_type", align 1
+  %a = alloca %struct.big_structure, align 32
+  %ref.tmp7 = alloca %struct.awaitable, align 1
+  %b = alloca %struct.big_structure.2, align 16
+  %ref.tmp18 = alloca %struct.awaitable, align 1
+  %0 = getelementptr inbounds %"struct.task::promise_type", %"struct.task::promise_type"* %__promise, i64 0, i32 0
+  %1 = call token @llvm.coro.id(i32 16, i8* nonnull %0, i8* bitcast (void (i1)* @a to i8*), i8* null)
+  br label %init.ready
+init.ready:
+  %2 = call noalias nonnull i8* @llvm.coro.begin(token %1, i8* null)
+  call void @llvm.lifetime.start.p0i8(i64 1, i8* nonnull %0)
+  br i1 %cond, label %if.then, label %if.else
+if.then:
+  %3 = getelementptr inbounds %struct.big_structure, %struct.big_structure* %a, i64 0, i32 0, i64 0
+  call void @llvm.lifetime.start.p0i8(i64 500, i8* nonnull %3)
+  call void @consume(%struct.big_structure* nonnull %a)
+  %save = call token @llvm.coro.save(i8* null)
+  %suspend = call i8 @llvm.coro.suspend(token %save, i1 false)
+  switch i8 %suspend, label %coro.ret [
+    i8 0, label %await.ready
+    i8 1, label %cleanup1
+  ]
+await.ready:
+  call void @llvm.lifetime.end.p0i8(i64 500, i8* nonnull %3)
+  br label %cleanup1
+if.else:
+  %4 = getelementptr inbounds %struct.big_structure.2, %struct.big_structure.2* %b, i64 0, i32 0, i64 0
+  call void @llvm.lifetime.start.p0i8(i64 400, i8* nonnull %4)
+  call void @consume.2(%struct.big_structure.2* nonnull %b)
+  %save2 = call token @llvm.coro.save(i8* null)
+  %suspend2 = call i8 @llvm.coro.suspend(token %save2, i1 false)
+  switch i8 %suspend2, label %coro.ret [
+    i8 0, label %await2.ready
+    i8 1, label %cleanup2
+  ]
+await2.ready:
+  call void @llvm.lifetime.end.p0i8(i64 400, i8* nonnull %4)
+  br label %cleanup2
+cleanup1:
+  call void @llvm.lifetime.end.p0i8(i64 500, i8* nonnull %3)
+  br label %cleanup
+cleanup2:
+  call void @llvm.lifetime.end.p0i8(i64 400, i8* nonnull %4)
+  br label %cleanup
+cleanup:
+  call i8* @llvm.coro.free(token %1, i8* %2)
+  br label %coro.ret
+coro.ret:
+  call i1 @llvm.coro.end(i8* null, i1 false)
+  ret void
+}
+; CHECK:       %a.Frame = type { void (%a.Frame*)*, void (%a.Frame*)*, %"struct.task::promise_type", i1, [14 x i8], %struct.big_structure }
+; CHECK-LABEL: @a.resume(
+; CHECK:         %[[A:.*]] = getelementptr inbounds %a.Frame, %a.Frame* %FramePtr, i32 0, i32 3
+; CHECK:         %[[A:.*]] = getelementptr inbounds %a.Frame, %a.Frame* %FramePtr, i32 0, i32 5
+
+declare token @llvm.coro.id(i32, i8* readnone, i8* nocapture readonly, i8*)
+declare i1 @llvm.coro.alloc(token) #3
+declare i64 @llvm.coro.size.i64() #5
+declare i8* @llvm.coro.begin(token, i8* writeonly) #3
+declare token @llvm.coro.save(i8*) #3
+declare i8* @llvm.coro.frame() #5
+declare i8 @llvm.coro.suspend(token, i1) #3
+declare i8* @llvm.coro.free(token, i8* nocapture readonly) #2
+declare i1 @llvm.coro.end(i8*, i1) #3
+declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture) #4
+declare void @llvm.lifetime.end.p0i8(i64, i8* nocapture) #4