diff --git a/clang/lib/AST/Interp/InterpStack.h b/clang/lib/AST/Interp/InterpStack.h
--- a/clang/lib/AST/Interp/InterpStack.h
+++ b/clang/lib/AST/Interp/InterpStack.h
@@ -13,7 +13,9 @@
 #ifndef LLVM_CLANG_AST_INTERP_INTERPSTACK_H
 #define LLVM_CLANG_AST_INTERP_INTERPSTACK_H
 
+#include "PrimType.h"
 #include <memory>
+#include <vector>
 
 namespace clang {
 namespace interp {
@@ -29,10 +31,18 @@
   /// Constructs a value in place on the top of the stack.
   template <typename T, typename... Tys> void push(Tys &&... Args) {
     new (grow(aligned_size<T>())) T(std::forward<Tys>(Args)...);
+#ifndef NDEBUG
+    ItemTypes.push_back(toPrimType<T>());
+#endif
   }
 
   /// Returns the value from the top of the stack and removes it.
   template <typename T> T pop() {
+#ifndef NDEBUG
+    assert(!ItemTypes.empty());
+    assert(ItemTypes.back() == toPrimType<T>());
+    ItemTypes.pop_back();
+#endif
     auto *Ptr = &peek<T>();
     auto Value = std::move(*Ptr);
     Ptr->~T();
@@ -42,6 +52,10 @@
 
   /// Discards the top value from the stack.
   template <typename T> void discard() {
+#ifndef NDEBUG
+    assert(ItemTypes.back() == toPrimType<T>());
+    ItemTypes.pop_back();
+#endif
     auto *Ptr = &peek<T>();
     Ptr->~T();
     shrink(aligned_size<T>());
@@ -108,6 +122,45 @@
   StackChunk *Chunk = nullptr;
   /// Total size of the stack.
   size_t StackSize = 0;
+
+#ifndef NDEBUG
+  /// vector recording the type of data we pushed into the stack.
+  std::vector<PrimType> ItemTypes;
+
+  template <typename T> static constexpr PrimType toPrimType() {
+    if constexpr (std::is_same_v<T, Pointer>)
+      return PT_Ptr;
+    else if constexpr (std::is_same_v<T, bool> ||
+                       std::is_same_v<T, Boolean>)
+      return PT_Bool;
+    else if constexpr (std::is_same_v<T, int8_t> ||
+                       std::is_same_v<T, Integral<8, true>>)
+      return PT_Sint8;
+    else if constexpr (std::is_same_v<T, uint8_t> ||
+                       std::is_same_v<T, Integral<8, false>>)
+      return PT_Uint8;
+    else if constexpr (std::is_same_v<T, int16_t> ||
+                       std::is_same_v<T, Integral<16, true>>)
+      return PT_Sint16;
+    else if constexpr (std::is_same_v<T, uint16_t> ||
+                       std::is_same_v<T, Integral<16, false>>)
+      return PT_Uint16;
+    else if constexpr (std::is_same_v<T, int32_t> ||
+                       std::is_same_v<T, Integral<32, true>>)
+      return PT_Sint32;
+    else if constexpr (std::is_same_v<T, uint32_t> ||
+                       std::is_same_v<T, Integral<32, false>>)
+      return PT_Uint32;
+    else if constexpr (std::is_same_v<T, int64_t> ||
+                       std::is_same_v<T, Integral<64, true>>)
+      return PT_Sint64;
+    else if constexpr (std::is_same_v<T, uint64_t> ||
+                       std::is_same_v<T, Integral<64, false>>)
+      return PT_Uint64;
+
+    llvm_unreachable("unknown type push()'ed into InterpStack");
+  }
+#endif
 };
 
 } // namespace interp