https://github.com/tbaederr updated 
https://github.com/llvm/llvm-project/pull/189410

>From 62e1d986269cd18dad078395c3582c1b9ab53c8a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timm=20B=C3=A4der?= <[email protected]>
Date: Tue, 10 Feb 2026 16:06:17 +0100
Subject: [PATCH] Exceptions

---
 clang/include/clang/Basic/Builtins.td         |   6 +
 .../include/clang/Basic/DiagnosticASTKinds.td |   3 +
 clang/include/clang/Basic/UnsignedOrNone.h    |   6 +
 clang/lib/AST/ByteCode/ByteCodeEmitter.cpp    |   3 +-
 clang/lib/AST/ByteCode/ByteCodeEmitter.h      |  10 +
 clang/lib/AST/ByteCode/Compiler.cpp           | 203 ++++-
 clang/lib/AST/ByteCode/Disasm.cpp             |   2 +
 clang/lib/AST/ByteCode/EvalEmitter.h          |  11 +
 clang/lib/AST/ByteCode/Function.h             |  25 +-
 clang/lib/AST/ByteCode/Interp.cpp             | 198 ++++-
 clang/lib/AST/ByteCode/Interp.h               | 315 +++++++-
 clang/lib/AST/ByteCode/InterpBuiltin.cpp      |  11 +
 clang/lib/AST/ByteCode/InterpFrame.h          |   1 +
 clang/lib/AST/ByteCode/InterpStack.cpp        |   6 +
 clang/lib/AST/ByteCode/InterpStack.h          |   2 +
 clang/lib/AST/ByteCode/InterpState.h          |  15 +
 clang/lib/AST/ByteCode/Opcodes.td             |  32 +-
 clang/lib/AST/ByteCode/PrimType.h             |   9 +
 clang/lib/AST/ByteCode/Source.h               |   2 +
 clang/test/AST/ByteCode/cxx20.cpp             |  15 +-
 clang/test/AST/ByteCode/cxx23.cpp             |   4 +-
 clang/test/AST/ByteCode/exceptions.cpp        | 705 ++++++++++++++++++
 clang/test/AST/ByteCode/invalid.cpp           |  30 +-
 clang/utils/TableGen/ClangOpcodesEmitter.cpp  |  12 +-
 24 files changed, 1544 insertions(+), 82 deletions(-)
 create mode 100644 clang/test/AST/ByteCode/exceptions.cpp

diff --git a/clang/include/clang/Basic/Builtins.td 
b/clang/include/clang/Basic/Builtins.td
index b8bbc544595e2..0e120bdd47fe4 100644
--- a/clang/include/clang/Basic/Builtins.td
+++ b/clang/include/clang/Basic/Builtins.td
@@ -5596,3 +5596,9 @@ def CountedByRef : Builtin {
   let Attributes = [NoThrow, CustomTypeChecking];
   let Prototype = "int(...)";
 }
+
+def ConstexprCurrentException: LangBuiltin<"CXX_LANG"> {
+  let Spellings = ["__builtin_current_exception"];
+  let Attributes = [NoThrow, Constexpr];
+  let Prototype = "void*()";
+}
diff --git a/clang/include/clang/Basic/DiagnosticASTKinds.td 
b/clang/include/clang/Basic/DiagnosticASTKinds.td
index bde418695f647..bd3fefd8c54a3 100644
--- a/clang/include/clang/Basic/DiagnosticASTKinds.td
+++ b/clang/include/clang/Basic/DiagnosticASTKinds.td
@@ -406,6 +406,9 @@ def note_constexpr_infer_alloc_token_no_metadata : Note<
   "could not get token metadata for inferred type">;
 def note_constexpr_infer_alloc_token_stateful_mode
     : Note<"stateful alloc token mode not supported in constexpr">;
+def note_constexpr_uncaught_exception : Note<"uncaught exception of type %0: 
'%1'">;
+
+def note_constexpr_exception_in_noexcept_func : Note<"uncaught exception in 
noexcept function">;
 
 def warn_attribute_needs_aggregate : Warning<
   "%0 attribute is ignored in non-aggregate type %1">,
diff --git a/clang/include/clang/Basic/UnsignedOrNone.h 
b/clang/include/clang/Basic/UnsignedOrNone.h
index 659fd8c6487d2..aa09ae998dee0 100644
--- a/clang/include/clang/Basic/UnsignedOrNone.h
+++ b/clang/include/clang/Basic/UnsignedOrNone.h
@@ -35,6 +35,12 @@ struct UnsignedOrNone {
     return Rep - 1;
   }
 
+  unsigned value_or(unsigned U) const {
+    if (operator bool())
+      return operator*();
+    return U;
+  }
+
   friend constexpr bool operator==(UnsignedOrNone LHS, UnsignedOrNone RHS) {
     return LHS.Rep == RHS.Rep;
   }
diff --git a/clang/lib/AST/ByteCode/ByteCodeEmitter.cpp 
b/clang/lib/AST/ByteCode/ByteCodeEmitter.cpp
index 393b8481fecd1..17cf076c52851 100644
--- a/clang/lib/AST/ByteCode/ByteCodeEmitter.cpp
+++ b/clang/lib/AST/ByteCode/ByteCodeEmitter.cpp
@@ -85,7 +85,8 @@ void ByteCodeEmitter::compileFunc(const FunctionDecl 
*FuncDecl,
 
   // Set the function's code.
   Func->setCode(FuncDecl, NextLocalOffset, std::move(Code), std::move(SrcMap),
-                std::move(Scopes), FuncDecl->hasBody(), IsValid);
+                std::move(Scopes), std::move(ExceptionTable),
+                FuncDecl->hasBody(), IsValid);
   Func->setIsFullyCompiled(true);
 }
 
diff --git a/clang/lib/AST/ByteCode/ByteCodeEmitter.h 
b/clang/lib/AST/ByteCode/ByteCodeEmitter.h
index 102ce939c6717..97a3b141cae71 100644
--- a/clang/lib/AST/ByteCode/ByteCodeEmitter.h
+++ b/clang/lib/AST/ByteCode/ByteCodeEmitter.h
@@ -76,6 +76,14 @@ class ByteCodeEmitter {
   llvm::SmallVector<SmallVector<Local, 8>, 2> Descriptors;
   std::optional<SourceInfo> LocOverride = std::nullopt;
 
+  unsigned currentCodeSize() const { return Code.size(); }
+
+  void registerExceptionHandler(unsigned From, unsigned To, unsigned Target,
+                                UnsignedOrNone DeclOffset, const Type *T) {
+    ExceptionTable.push_back(
+        ExceptionTableEntry{From, To, Target, DeclOffset, T});
+  }
+
 private:
   /// Current compilation context.
   Context &Ctx;
@@ -91,9 +99,11 @@ class ByteCodeEmitter {
   llvm::DenseMap<LabelTy, llvm::SmallVector<unsigned, 5>> LabelRelocs;
   /// Program code.
   llvm::SmallVector<std::byte> Code;
+  llvm::SmallVector<ExceptionTableEntry> ExceptionTable;
   /// Opcode to expression mapping.
   SourceMap SrcMap;
 
+public:
   /// Returns the offset for a jump or records a relocation.
   int32_t getOffset(LabelTy Label);
 
diff --git a/clang/lib/AST/ByteCode/Compiler.cpp 
b/clang/lib/AST/ByteCode/Compiler.cpp
index 4f517266336f2..5fc134bd9c415 100644
--- a/clang/lib/AST/ByteCode/Compiler.cpp
+++ b/clang/lib/AST/ByteCode/Compiler.cpp
@@ -36,6 +36,21 @@ static std::optional<bool> getBoolValue(const Expr *E) {
   return std::nullopt;
 }
 
+// FIXME: Use this again.
+#if 0
+static bool blockEndsInReturn(const Stmt *S) {
+  if (isa<ReturnStmt>(S))
+    return true;
+
+  if (const auto *CS = dyn_cast<CompoundStmt>(S);
+     CS && !CS->body_empty()) {
+    return isa<ReturnStmt>(CS->body_back());
+  }
+
+  return false;
+}
+#endif
+
 /// Scope used to handle temporaries in toplevel variable declarations.
 template <class Emitter> class DeclScope final : public LocalScope<Emitter> {
 public:
@@ -3455,10 +3470,152 @@ bool Compiler<Emitter>::VisitPredefinedExpr(const 
PredefinedExpr *E) {
 
 template <class Emitter>
 bool Compiler<Emitter>::VisitCXXThrowExpr(const CXXThrowExpr *E) {
-  if (E->getSubExpr() && !this->discard(E->getSubExpr()))
+  const Expr *SubExpr = E->getSubExpr();
+  if (!Ctx.getLangOpts().CPlusPlus26 || !Ctx.getLangOpts().CXXExceptions) {
+    if (SubExpr && !this->discard(SubExpr))
+      return false;
+    return this->emitInvalid(E);
+  }
+
+  assert(E->getSubExpr()); // XXX
+
+  llvm::errs() << __PRETTY_FUNCTION__ << '\n';
+  E->dumpColor();
+
+  QualType ExceptionType = SubExpr->getType();
+  OptPrimType ExceptionT = classify(SubExpr);
+  if (ExceptionT)
+    llvm::errs() << "ExceptionT: " << *ExceptionT << '\n';
+  else
+    llvm::errs() << "ExceptionT: None\n";
+
+  const Descriptor *Desc;
+  if (ExceptionT)
+    Desc = P.createDescriptor(SubExpr, *ExceptionT);
+  else
+    Desc = P.createDescriptor(SubExpr, ExceptionType.getTypePtr(), 
std::nullopt,
+                              /*IsConst=*/false);
+
+  if (!this->emitAllocException(Desc, E))
     return false;
 
-  return this->emitInvalid(E);
+  bool Comp;
+  if (ExceptionT) {
+    Comp = false;
+    if (!this->visit(SubExpr))
+      return false;
+    if (!this->emitInit(*ExceptionT, E))
+      return false;
+  } else {
+    Comp = true;
+    if (!this->visitInitializer(SubExpr))
+      return false;
+  }
+
+  this->VarScope->destroyLocals();
+
+  PrimType T = classify(E->getSubExpr()).value_or(PT_Ptr);
+  return this->emitThrow(T, ExceptionType.getTypePtr(), Comp, E);
+}
+
+template <class Emitter>
+bool Compiler<Emitter>::visitCXXTryStmt(const CXXTryStmt *S) {
+  if (!Ctx.getLangOpts().CPlusPlus26 || !Ctx.getLangOpts().CXXExceptions) {
+    // Ignore all handlers.
+    return this->visitStmt(S->getTryBlock());
+  }
+
+  // LocalScope<Emitter> FullScope(this);
+
+  S->dumpColor();
+  unsigned NumHandlers = S->getNumHandlers();
+  llvm::errs() << "Handlers: " << NumHandlers << '\n';
+
+  if (!this->emitThrowTrap(S))
+    return false;
+
+  unsigned s = this->currentCodeSize();
+
+  // Emit try block contents.
+  const auto *TryBlock = cast<CompoundStmt>(S->getTryBlock());
+  LocalScope<Emitter> TryBlockScope(this);
+  for (const auto *InnerStmt : TryBlock->body()) {
+    if (!visitStmt(InnerStmt))
+      return false;
+  }
+
+  if (!TryBlockScope.destroyLocals())
+    return false;
+  // Unlink this scope. We will emit cleanups for it again later.
+  assert(this->VarScope == &TryBlockScope);
+  this->VarScope = TryBlockScope.getParent();
+
+  unsigned e = this->currentCodeSize();
+
+  // Jump after handlers if nothing was thrown.
+  LabelTy EndLabel = this->getLabel();
+  this->jump(EndLabel, S);
+
+  // Register and emit all handlers.
+  for (unsigned I = 0; I != NumHandlers; ++I) {
+    const CXXCatchStmt *Handler = S->getHandler(I);
+    const Stmt *HandlerBlock = Handler->getHandlerBlock();
+    const VarDecl *ExceptionDecl = Handler->getExceptionDecl();
+    QualType CatchType = Handler->getCaughtType();
+    UnsignedOrNone ExceptionDeclOffset = std::nullopt;
+
+    unsigned t = this->currentCodeSize();
+    if (ExceptionDecl) {
+      llvm::errs() << "EXCEPTION DECL:\n";
+      ExceptionDecl->dump();
+
+      if (OptPrimType T = classify(CatchType)) {
+        unsigned LocalOffset = allocateLocalPrimitive(ExceptionDecl, *T,
+                                                      /*IsConst=*/true);
+        if (!this->emitGetExceptionValue(*T, S))
+          return false;
+        if (!this->emitSetLocal(*T, LocalOffset, S))
+          return false;
+      } else {
+        UnsignedOrNone LocalOffset = allocateLocal(ExceptionDecl, CatchType);
+        if (!LocalOffset)
+          return false;
+
+        if (!this->emitGetPtrLocal(*LocalOffset, Handler))
+          return false;
+        if (!this->emitGetExceptionValuePtr(Handler))
+          return false;
+        if (!this->emitMemcpy(Handler))
+          return false;
+        if (!this->emitPopPtr(Handler))
+          return false;
+      }
+    } else {
+      // This is a catch-all handler.
+      if (!this->emitClearExceptionValue(S))
+        return false;
+    }
+
+    const Type *CatchTypePtr = CatchType.getTypePtrOrNull();
+
+    this->registerExceptionHandler(s, e, t, ExceptionDeclOffset, CatchTypePtr);
+    if (!this->visitStmt(HandlerBlock))
+      return false;
+    // FIXME: Re-enable this.
+    // if (blockEndsInReturn(Block))
+    // continue;
+    this->jump(EndLabel, S);
+  }
+
+  this->fallthrough(EndLabel);
+  this->emitLabel(EndLabel);
+
+  // return FullScope.destroyLocals();
+
+  // if (!TryBlockScope.destroyLocals())
+  // return false;
+
+  return true;
 }
 
 template <class Emitter>
@@ -6579,12 +6736,6 @@ bool Compiler<Emitter>::visitAttributedStmt(const 
AttributedStmt *S) {
   return true;
 }
 
-template <class Emitter>
-bool Compiler<Emitter>::visitCXXTryStmt(const CXXTryStmt *S) {
-  // Ignore all handlers.
-  return this->visitStmt(S->getTryBlock());
-}
-
 template <class Emitter>
 bool Compiler<Emitter>::emitLambdaStaticInvokerBody(const CXXMethodDecl *MD) {
   assert(MD->isLambdaStaticInvoker());
@@ -6847,8 +6998,17 @@ bool Compiler<Emitter>::compileConstructor(const 
CXXConstructorDecl *Ctor) {
         return false;
     }
 
-    if (!visitStmt(Body))
-      return false;
+    if (isa<CompoundStmt>(Body)) {
+      if (!visitStmt(Body))
+        return false;
+    } else {
+      // direct try {} body.
+      LocalScope<Emitter> Scope(this);
+      if (!visitStmt(Body))
+        return false;
+      if (!Scope.destroyLocals())
+        return false;
+    }
   }
 
   return this->emitRetVoid(SourceInfo{});
@@ -6915,6 +7075,9 @@ bool Compiler<Emitter>::compileUnionAssignmentOperator(
 
 template <class Emitter>
 bool Compiler<Emitter>::visitFunc(const FunctionDecl *F) {
+  llvm::errs() << __PRETTY_FUNCTION__ << '\n';
+  F->dumpColor();
+
   // Classify the return type.
   ReturnType = this->classify(F->getReturnType());
 
@@ -6938,14 +7101,24 @@ bool Compiler<Emitter>::visitFunc(const FunctionDecl 
*F) {
   }
 
   // Regular functions.
-  if (const auto *Body = F->getBody())
-    if (!visitStmt(Body))
-      return false;
+  if (const auto *Body = F->getBody()) {
+    if (isa<CompoundStmt>(Body)) {
+      if (!visitStmt(Body))
+        return false;
+    } else {
+      // direct try {} body.
+      LocalScope<Emitter> Scope(this);
+      if (!visitStmt(Body))
+        return false;
+      if (!Scope.destroyLocals())
+        return false;
+    }
+  }
 
   // Emit a guard return to protect against a code path missing one.
   if (F->getReturnType()->isVoidType())
-    return this->emitRetVoid(SourceInfo{});
-  return this->emitNoRet(SourceInfo{});
+    return this->emitRetVoid(SourceInfo{}) && this->emitAfterRet(SourceInfo{});
+  return this->emitNoRet(SourceInfo{}) && this->emitAfterRet(SourceInfo{});
 }
 
 static uint32_t getBitWidth(const Expr *E) {
diff --git a/clang/lib/AST/ByteCode/Disasm.cpp 
b/clang/lib/AST/ByteCode/Disasm.cpp
index 6caa33261dad6..a5c61178bffd4 100644
--- a/clang/lib/AST/ByteCode/Disasm.cpp
+++ b/clang/lib/AST/ByteCode/Disasm.cpp
@@ -179,6 +179,8 @@ LLVM_DUMP_METHOD void Function::dump(llvm::raw_ostream &OS,
     Text.Addr = Addr;
     Text.IsJump = isJumpOpcode(Op);
     Text.CurrentOp = (PC == OpPC);
+    // llvm::errs() << (void*)(*PC) << " / " << (void*)(*OpPC) << ((*OpPC -
+    // *PC)) << '\n';
     switch (Op) {
 #define GET_DISASM
 #include "Opcodes.inc"
diff --git a/clang/lib/AST/ByteCode/EvalEmitter.h 
b/clang/lib/AST/ByteCode/EvalEmitter.h
index 8f6da7aef422a..479c659d7a120 100644
--- a/clang/lib/AST/ByteCode/EvalEmitter.h
+++ b/clang/lib/AST/ByteCode/EvalEmitter.h
@@ -54,6 +54,17 @@ class EvalEmitter : public SourceMapper {
 
   virtual ~EvalEmitter();
 
+  unsigned getOffset(LabelTy L) { return 0; }
+  unsigned currentCodeSize() const {
+    llvm_unreachable("Should never be called on EvalEmitter");
+    return 0;
+  }
+
+  void registerExceptionHandler(unsigned From, unsigned To, unsigned Target,
+                                UnsignedOrNone, const Type *T) {
+    llvm_unreachable("Should never be called on EvalEmitter");
+  }
+
   /// Define a label.
   void emitLabel(LabelTy Label);
   /// Create a label.
diff --git a/clang/lib/AST/ByteCode/Function.h 
b/clang/lib/AST/ByteCode/Function.h
index 90732d6dc01a4..8f3b11c215916 100644
--- a/clang/lib/AST/ByteCode/Function.h
+++ b/clang/lib/AST/ByteCode/Function.h
@@ -63,6 +63,15 @@ class Scope final {
   LocalVectorTy Descriptors;
 };
 
+struct ExceptionTableEntry {
+  unsigned CodeStart;
+  unsigned CodeEnd;
+  unsigned Target;
+  UnsignedOrNone DeclOffset;
+  /// If CatchType is nullptr, this is a catch-all handler.
+  const Type *CatchType;
+};
+
 using FunctionDeclTy =
     llvm::PointerUnion<const FunctionDecl *, const BlockExpr *>;
 
@@ -247,6 +256,16 @@ class Function final {
     return false;
   }
 
+  unsigned getParamOffset(unsigned ParamIndex) const {
+    return ParamDescriptors[ParamIndex].Offset;
+  }
+
+  PrimType getParamType(unsigned ParamIndex) const {
+    return ParamDescriptors[ParamIndex].T;
+  }
+
+  llvm::SmallVector<ExceptionTableEntry> ExceptionTable;
+
 private:
   /// Construct a function representing an actual function.
   Function(Program &P, FunctionDeclTy Source, unsigned ArgSize,
@@ -256,13 +275,15 @@ class Function final {
   /// Sets the code of a function.
   void setCode(FunctionDeclTy Source, unsigned NewFrameSize,
                llvm::SmallVector<std::byte> &&NewCode, SourceMap &&NewSrcMap,
-               llvm::SmallVector<Scope, 2> &&NewScopes, bool NewHasBody,
-               bool NewIsValid) {
+               llvm::SmallVector<Scope, 2> &&NewScopes,
+               llvm::SmallVector<ExceptionTableEntry> &&ExceptionTable,
+               bool NewHasBody, bool NewIsValid) {
     this->Source = Source;
     FrameSize = NewFrameSize;
     Code = std::move(NewCode);
     SrcMap = std::move(NewSrcMap);
     Scopes = std::move(NewScopes);
+    this->ExceptionTable = std::move(ExceptionTable);
     IsValid = NewIsValid;
     HasBody = NewHasBody;
   }
diff --git a/clang/lib/AST/ByteCode/Interp.cpp 
b/clang/lib/AST/ByteCode/Interp.cpp
index 8cc3c9216f7f4..f73461209e820 100644
--- a/clang/lib/AST/ByteCode/Interp.cpp
+++ b/clang/lib/AST/ByteCode/Interp.cpp
@@ -24,6 +24,7 @@
 #include "clang/Basic/DiagnosticSema.h"
 #include "clang/Basic/TargetInfo.h"
 #include "llvm/ADT/StringExtras.h"
+#include <variant>
 
 using namespace clang;
 using namespace clang::interp;
@@ -754,7 +755,7 @@ bool CheckGlobalLoad(InterpState &S, CodePtr OpPC, const 
Block *B) {
 // Similarly, for local loads.
 bool CheckLocalLoad(InterpState &S, CodePtr OpPC, const Block *B) {
   assert(!B->isExtern());
-  const auto &Desc = *reinterpret_cast<const InlineDescriptor *>(B->rawData());
+  const auto &Desc = B->getBlockDesc<const InlineDescriptor>();
   if (!CheckLifetime(S, OpPC, Desc.LifeState, AK_Read))
     return false;
   if (!Desc.IsInitialized)
@@ -1232,7 +1233,7 @@ static bool runRecordDestructor(InterpState &S, CodePtr 
OpPC,
     return false;
 
   S.Stk.push<Pointer>(BasePtr);
-  return Call(S, OpPC, DtorFunc, 0);
+  return Call(S, OpPC, OpPC, DtorFunc, 0);
 }
 
 static bool RunDestructors(InterpState &S, CodePtr OpPC, const Block *B) {
@@ -1638,16 +1639,16 @@ bool CallVar(InterpState &S, CodePtr OpPC, const 
Function *Func,
   S.Current = FrameBefore;
   return false;
 }
-bool Call(InterpState &S, CodePtr OpPC, const Function *Func,
+bool Call(InterpState &S, CodePtr &PC, CodePtr OpPC, const Function *Func,
           uint32_t VarArgSize) {
-
+  // CodePtr OpPC = PC - align(sizeof(uint32_t)) - align(sizeof(void*));
   // C doesn't have constexpr functions.
   if (!S.getLangOpts().CPlusPlus)
-    return Invalid(S, OpPC);
+    return Invalid(S, PC);
 
   assert(Func);
   auto cleanup = [&]() -> bool {
-    cleanupAfterFunctionCall(S, OpPC, Func);
+    cleanupAfterFunctionCall(S, PC, Func);
     return false;
   };
 
@@ -1705,6 +1706,8 @@ bool Call(InterpState &S, CodePtr OpPC, const Function 
*Func,
 
   auto Memory = new char[InterpFrame::allocSize(Func)];
   auto NewFrame = new (Memory) InterpFrame(S, Func, OpPC, VarArgSize);
+  Func->dump();
+
   InterpFrame *FrameBefore = S.Current;
   S.Current = NewFrame;
 
@@ -1713,6 +1716,7 @@ bool Call(InterpState &S, CodePtr OpPC, const Function 
*Func,
   // Ret() above only sets the APValue if the curent frame doesn't
   // have a caller set.
   bool Success = Interpret(S);
+
   // Remove initializing  block again.
   if (Func->isConstructor() || Func->isDestructor())
     S.InitializingBlocks.pop_back();
@@ -1725,7 +1729,159 @@ bool Call(InterpState &S, CodePtr OpPC, const Function 
*Func,
     return false;
   }
 
-  assert(S.Current == FrameBefore);
+  if (S.ThrownValue) {
+    llvm::errs() << "WE HAVE A THROWN VALUE in CALL\n";
+    // If we have a thrown value in the InterpState, it was thrown in the
+    // function we just called (or deeper down in the stack), but not caught. 
We
+    // now need to check if the current function can call it.
+    const Function *CurrFunction = S.Current->getFunction();
+    if (!CurrFunction) {
+      llvm::errs() << "BUT NO FUNCTION, SO DIAGNOSING\n";
+      assert(S.Current->isBottomFrame());
+      if (!S.checkingPotentialConstantExpression()) {
+        QualType UncaughtType = QualType(S.ThrownValue->Ty, 0);
+        std::string ValString;
+        TYPE_SWITCH(S.ThrownValue->T, {
+          ValString = std::get<T>(S.ThrownValue->Value)
+                          .toDiagnosticString(S.getASTContext());
+        });
+        S.FFDiag(S.ThrownValue->ThrowSite,
+                 diag::note_constexpr_uncaught_exception)
+            << UncaughtType << ValString;
+      }
+      return false;
+    }
+    auto canCatch = [](const Type *CatchType, const Type *ThrowType) -> bool {
+      if (!CatchType || ASTContext::hasSameType(CatchType, ThrowType))
+        return true;
+
+      assert(CatchType);
+
+      // if (const auto *L = CatchType->getAs<ReferenceType>()) {
+      // return L->getPointeeType().getTypePtr() == ThrowType;
+      // }
+
+      // nullptr_t can be caught by any pointer type.
+      if (ThrowType->isNullPtrType() && CatchType->isPointerType())
+        return true;
+
+      // void* can catch all thown pointer types.
+      if (ThrowType->isPointerType() && CatchType->isVoidPointerType())
+        return true;
+
+      if (CatchType->isPointerOrReferenceType())
+        CatchType = CatchType->getPointeeType().getTypePtr();
+      if (ThrowType->isPointerOrReferenceType())
+        ThrowType = ThrowType->getPointeeType().getTypePtr();
+
+      if (CatchType->isRecordType() && ThrowType->isRecordType()) {
+        const CXXRecordDecl *CatchDecl = CatchType->getAsCXXRecordDecl();
+        const CXXRecordDecl *ThrowDecl = ThrowType->getAsCXXRecordDecl();
+        assert(CatchDecl);
+        assert(ThrowDecl);
+
+        if (CatchDecl == ThrowDecl)
+          return true;
+        if (ThrowDecl->isDerivedFrom(CatchDecl))
+          return true;
+      }
+
+      return false;
+    };
+
+    bool Caught = false;
+    unsigned CodeOffset = PC - CurrFunction->getCodeBegin();
+    for (const auto &E : CurrFunction->ExceptionTable) {
+      if (E.CodeStart <= CodeOffset && E.CodeEnd >= CodeOffset &&
+          (canCatch(E.CatchType, S.ThrownValue->Ty))) {
+
+        const Type *CaughtType = E.CatchType;
+        const Type *It = S.ThrownValue->Ty;
+
+        llvm::errs() << "Resetting stack to " << S.ThrowTrapStackSize << '\n';
+        while (S.Stk.size() != S.ThrowTrapStackSize) {
+          S.Stk.discardSlow();
+        }
+
+        bool NeedsCast =
+            CaughtType &&
+            ((CaughtType->isRecordType() && It->isRecordType()) ||
+             (CaughtType->isPointerOrReferenceType() &&
+              CaughtType->getPointeeType()->isRecordType() &&
+              It->isPointerOrReferenceType() &&
+              It->getPointeeType()->isRecordType())
+
+             || (It->isRecordType() && CaughtType->isReferenceType() &&
+                 CaughtType->getPointeeType()->isRecordType()));
+
+        llvm::errs() << "NeedsCast: " << NeedsCast << '\n';
+
+        if (NeedsCast) {
+          llvm::errs() << "CASTING AFTER CALL\n";
+          Pointer ThrownValue = std::get<Pointer>(S.ThrownValue->Value);
+          Pointer CastedValue =
+              ThrownValue; // std::get<Pointer>(S.ThrownValue->Value);
+          llvm::errs() << "ThrownValue: " << ThrownValue << '\n';
+
+          if (CaughtType->isPointerOrReferenceType())
+            CaughtType = CaughtType->getPointeeType().getTypePtr();
+
+          if (It->isPointerOrReferenceType())
+            It = It->getPointeeType().getTypePtr();
+          const Record *CaughtRecord =
+              S.getContext().getRecord(CaughtType->getAsCXXRecordDecl());
+          const Record *ItRecord =
+              S.getContext().getRecord(It->getAsCXXRecordDecl());
+          while (ItRecord != CaughtRecord) {
+            llvm::errs() << It << " / " << CaughtType << '\n';
+            const Record *R =
+                S.getContext().getRecord(It->getAsCXXRecordDecl());
+            assert(R);
+            llvm::errs() << "It record: " << R->getName() << '\n';
+            for (const Record::Base &B : R->bases()) {
+              if (cast<CXXRecordDecl>(ItRecord->getDecl())
+                      ->isDerivedFrom(cast<CXXRecordDecl>(
+                          B.Decl))) { //(cast<CXXRecordDecl>(B.Decl)->
+                                      // if (B.R == CaughtRecord) {
+                llvm::errs() << "yay!\n";
+                llvm::errs() << "Casted Value: " << CastedValue << '\n';
+                CastedValue = CastedValue.atField(B.Offset);
+                llvm::errs() << "Casted Value: " << CastedValue << '\n';
+                It = CastedValue.getType().getTypePtr();
+                ItRecord = S.getContext().getRecord(It->getAsCXXRecordDecl());
+                // return true;
+                break;
+              }
+            }
+          }
+
+          S.ThrownValue->Value = CastedValue;
+        }
+
+        llvm::errs() << "AAAAAAAHA! IN " << CurrFunction->getName() << "\n";
+        PC = S.Current->getFunction()->getCodeBegin() + E.Target;
+        llvm::errs() << "Offset now: "
+                     << (PC - S.Current->getFunction()->getCodeBegin()) << 
'\n';
+        Caught = true;
+        break;
+      }
+    }
+
+    if (!Caught) {
+      bool IsNoExcept = S.Current->getFunction()
+                            ->getDecl()
+                            ->getType()
+                            ->getAs<FunctionProtoType>()
+                            ->hasNoexceptExceptionSpec();
+
+      if (IsNoExcept)
+        S.CCEDiag(S.Current->getSource(OpPC),
+                  diag::note_constexpr_exception_in_noexcept_func);
+      PC = S.Current->getFunction()->getCodeEnd() - align(sizeof(Opcode));
+    }
+  }
+
+  // assert(S.Current == FrameBefore);
   return true;
 }
 
@@ -1819,7 +1975,7 @@ bool CallVirt(InterpState &S, CodePtr OpPC, const 
Function *Func,
     }
   }
 
-  if (!Call(S, OpPC, Func, VarArgSize))
+  if (!Call(S, OpPC, OpPC, Func, VarArgSize))
     return false;
 
   // Covariant return types. The return type of Overrider is a pointer
@@ -1855,7 +2011,7 @@ bool CallBI(InterpState &S, CodePtr OpPC, const CallExpr 
*CE,
   return InterpretBuiltin(S, OpPC, CE, BuiltinID);
 }
 
-bool CallPtr(InterpState &S, CodePtr OpPC, uint32_t ArgSize,
+bool CallPtr(InterpState &S, CodePtr &PC, CodePtr OpPC, uint32_t ArgSize,
              const CallExpr *CE) {
   const Pointer &Ptr = S.Stk.pop<Pointer>();
 
@@ -1914,7 +2070,7 @@ bool CallPtr(InterpState &S, CodePtr OpPC, uint32_t 
ArgSize,
   if (F->isVirtual())
     return CallVirt(S, OpPC, F, VarArgSize);
 
-  return Call(S, OpPC, F, VarArgSize);
+  return Call(S, PC, OpPC, F, VarArgSize);
 }
 
 static void startLifetimeRecurse(const Pointer &Ptr) {
@@ -2609,14 +2765,22 @@ bool Interpret(InterpState &S) {
   return InterpNext(S, PC);
 #else
   while (true) {
-    auto Op = PC.read<Opcode>();
-    auto Fn = InterpFunctions[Op];
+    // Empty program.
+    if (!PC)
+      return true;
 
-    if (!Fn(S, PC))
-      return false;
-    if (OpReturns(Op))
-      break;
-  }
+    for (;;) {
+      if (S.Current->getFunction())
+        llvm::errs() << "Interpret loop: "
+                     << S.Current->getFunction()->getName() << '\n';
+      auto Op = PC.read<Opcode>();
+      auto Fn = InterpFunctions[Op];
+
+      if (!Fn(S, PC))
+        return false;
+      if (OpReturns(Op))
+        break;
+    }
   return true;
 #endif
 }
diff --git a/clang/lib/AST/ByteCode/Interp.h b/clang/lib/AST/ByteCode/Interp.h
index 91e9461befcd9..3cf670cc85297 100644
--- a/clang/lib/AST/ByteCode/Interp.h
+++ b/clang/lib/AST/ByteCode/Interp.h
@@ -26,6 +26,7 @@
 #include "InterpStack.h"
 #include "InterpState.h"
 #include "MemberPointer.h"
+#include "Opcode.h"
 #include "PrimType.h"
 #include "Program.h"
 #include "State.h"
@@ -116,13 +117,13 @@ bool SetThreeWayComparisonField(InterpState &S, CodePtr 
OpPC,
 
 bool CallVar(InterpState &S, CodePtr OpPC, const Function *Func,
              uint32_t VarArgSize);
-bool Call(InterpState &S, CodePtr OpPC, const Function *Func,
+bool Call(InterpState &S, CodePtr &PC, CodePtr OpPC, const Function *Func,
           uint32_t VarArgSize);
 bool CallVirt(InterpState &S, CodePtr OpPC, const Function *Func,
               uint32_t VarArgSize);
 bool CallBI(InterpState &S, CodePtr OpPC, const CallExpr *CE,
             uint32_t BuiltinID);
-bool CallPtr(InterpState &S, CodePtr OpPC, uint32_t ArgSize,
+bool CallPtr(InterpState &S, CodePtr &PC, CodePtr OpPC, uint32_t ArgSize,
              const CallExpr *CE);
 bool CheckLiteralType(InterpState &S, CodePtr OpPC, const Type *T);
 bool InvalidShuffleVectorIndex(InterpState &S, CodePtr OpPC, uint32_t Index);
@@ -249,6 +250,8 @@ void cleanupAfterFunctionCall(InterpState &S, CodePtr OpPC,
 
 template <PrimType Name, class T = typename PrimConv<Name>::T>
 PRESERVE_NONE bool Ret(InterpState &S, CodePtr &PC) {
+  llvm::errs() << "Ret in " << S.Current->getFunction()->getName() << "!\n";
+  S.Stk.dump();
   const T &Ret = S.Stk.pop<T>();
 
   assert(S.Current);
@@ -289,6 +292,261 @@ PRESERVE_NONE inline bool RetVoid(InterpState &S, CodePtr 
&PC) {
   return true;
 }
 
+template <PrimType Name, class T = typename PrimConv<Name>::T>
+bool Throw(InterpState &S, CodePtr &PC, const Type *Ty, bool IsComp) {
+  llvm::errs() << 
"############################################################"
+                  "###################################\n";
+  CodePtr OpPC;
+  if (PC)
+    OpPC = PC - align(sizeof(Opcode)) - align(sizeof(bool)); // XXX
+  else
+    OpPC = PC;
+
+  auto canCatch = [](const Type *CatchType, const Type *ThrowType) -> bool {
+    if (!CatchType || ASTContext::hasSameType(CatchType, ThrowType))
+      return true;
+
+    assert(CatchType);
+
+    // nullptr_t can be caught by any pointer type.
+    if (ThrowType->isNullPtrType() && CatchType->isPointerType())
+      return true;
+
+    // void* can catch all thown pointer types.
+    if (ThrowType->isPointerType() && CatchType->isVoidPointerType())
+      return true;
+
+    if (CatchType->isPointerOrReferenceType())
+      CatchType = CatchType->getPointeeType().getTypePtr();
+    if (ThrowType->isPointerOrReferenceType())
+      ThrowType = ThrowType->getPointeeType().getTypePtr();
+
+    if (CatchType->isRecordType() && ThrowType->isRecordType()) {
+      const CXXRecordDecl *CatchDecl = CatchType->getAsCXXRecordDecl();
+      const CXXRecordDecl *ThrowDecl = ThrowType->getAsCXXRecordDecl();
+      assert(CatchDecl);
+      assert(ThrowDecl);
+
+      if (CatchDecl == ThrowDecl)
+        return true;
+
+      if (ThrowDecl->isDerivedFrom(CatchDecl))
+        return true;
+    }
+
+    return false;
+  };
+
+  // TODO: Diagnose.
+  if (S.Current->isBottomFrame())
+    return false;
+
+  const auto &ThrownValue = S.Stk.pop<Pointer>();
+
+  assert(S.Current->getFrameOffset() == S.Stk.size() && "Invalid frame");
+  llvm::errs() << "\n\n" << __PRETTY_FUNCTION__ << '\n';
+  llvm::errs() << "Throwing " << ThrownValue << '\n';
+  llvm::errs() << "In " << S.Current->getName() << '\n';
+  unsigned O = PC - S.Current->getFunction()->getCodeBegin();
+  llvm::errs() << "O: " << O << ". Type: " << Ty << '\n';
+  bool Caught = false;
+
+  llvm::errs() << "Thrown Type:\n";
+  Ty->dump();
+
+  const Function *F = S.Current->getFunction();
+  if (!F) {
+    assert(false);
+  }
+  CodePtr CurrentPC = PC;
+  llvm::errs() << "Current function: " << F->getName() << '\n';
+  unsigned CodeOffset = CurrentPC - F->getCodeBegin();
+  llvm::errs() << "CodeOffset:  " << CodeOffset << '\n';
+
+  const Type *CaughtType = nullptr;
+
+  for (const auto &E : F->ExceptionTable) {
+    if (E.CatchType) {
+      llvm::errs() << "Catching:\n";
+      E.CatchType->dump();
+    }
+    llvm::errs() << "Can catch: " << canCatch(E.CatchType, Ty) << '\n';
+
+    if (E.CodeStart <= CodeOffset && E.CodeEnd >= CodeOffset &&
+        canCatch(E.CatchType, Ty)) {
+      llvm::errs() << "SAME FRAME\n";
+      PC = S.Current->getFunction()->getCodeBegin() + E.Target;
+
+      llvm::errs() << "new offset: "
+                   << (PC - S.Current->getFunction()->getCodeBegin()) << '\n';
+
+      llvm::errs() << "FOUND!\n";
+      Caught = true;
+      CaughtType = E.CatchType;
+
+      break;
+    }
+  }
+
+  const CXXThrowExpr *Source = cast<CXXThrowExpr>(S.Current->getExpr(OpPC));
+  llvm::errs() << "Comp: " << IsComp << '\n';
+  if (!IsComp) {
+
+    Pointer CastedValue = ThrownValue;
+    const Type *It = ThrownValue.getType().getTypePtr();
+
+    llvm::errs() << 
"----------------------------------------------------------"
+                    "------------\n";
+    bool NeedsCast =
+        CaughtType && ((CaughtType->isRecordType() && It->isRecordType()) ||
+                       (CaughtType->isPointerOrReferenceType() &&
+                        CaughtType->getPointeeType()->isRecordType() &&
+                        It->isPointerOrReferenceType() &&
+                        It->getPointeeType()->isRecordType()));
+
+    llvm::errs() << "NeedsCast: " << NeedsCast << '\n';
+
+    // if (CaughtType && CaughtType->isRecordType() && It->isRecordType()) {
+    if (NeedsCast) {
+      CastedValue = CastedValue.deref<Pointer>();
+      llvm::errs() << "WE ARE CASTING\n";
+      It = It->getPointeeType().getTypePtr();
+      const Record *CaughtRecord = S.getContext().getRecord(
+          CaughtType->getPointeeType()->getAsCXXRecordDecl());
+      const Record *ItRecord =
+          S.getContext().getRecord(It->getAsCXXRecordDecl());
+      while (ItRecord != CaughtRecord) {
+        llvm::errs() << It << " / " << CaughtType << '\n';
+        const Record *R = S.getContext().getRecord(It->getAsCXXRecordDecl());
+        assert(R);
+        llvm::errs() << "It record: " << R->getName() << '\n';
+        for (const Record::Base &B : R->bases()) {
+          if (cast<CXXRecordDecl>(ItRecord->getDecl())
+                  ->isDerivedFrom(cast<CXXRecordDecl>(
+                      B.Decl))) { //(cast<CXXRecordDecl>(B.Decl)->
+                                  // if (B.R == CaughtRecord) {
+            llvm::errs() << "yay!\n";
+            llvm::errs() << "Casted Value: " << CastedValue << '\n';
+            CastedValue = CastedValue.atField(B.Offset);
+            llvm::errs() << "Casted Value: " << CastedValue << '\n';
+            It = CastedValue.getType().getTypePtr();
+            ItRecord = S.getContext().getRecord(It->getAsCXXRecordDecl());
+            // return true;
+            break;
+          }
+        }
+      }
+      S.ThrownValue = ThrowValue{Ty, Source, CastedValue, Name};
+    } else {
+      S.ThrownValue = ThrowValue{Ty, Source, ThrownValue.deref<T>(), Name};
+    }
+
+  } else {
+    llvm::errs() << 
"----------------------------------------------------------"
+                    "------------\n";
+    llvm::errs() << "Value: " << ThrownValue << '\n';
+    assert((std::is_same_v<T, Pointer>));
+    // llvm::errs() << "Direct hit: "
+    // << (ThrownValue.getType().getTypePtr() == CaughtType) << '\n';
+    // We need to cast the thrown value to the expected caught type.
+    // FIXME: Add more tests.
+    // FIXME: We need to be careful here becuase of virtual and multiple
+    // inheritance.
+    //        Add tests for that as well.
+    Pointer CastedValue = ThrownValue;
+    const Type *It = ThrownValue.getType().getTypePtr();
+
+    bool NeedsCast = CaughtType &&
+                     ((CaughtType->isRecordType() && It->isRecordType()) ||
+                      (CaughtType->isPointerOrReferenceType() &&
+                       CaughtType->getPointeeType()->isRecordType() &&
+                       It->isPointerOrReferenceType() &&
+                       It->getPointeeType()->isRecordType())
+
+                      || (It->isRecordType() && CaughtType->isReferenceType() 
&&
+                          CaughtType->getPointeeType()->isRecordType()));
+
+    llvm::errs() << "NeedsCast: " << NeedsCast << '\n';
+
+    if (CaughtType && CaughtType->isPointerOrReferenceType())
+      CaughtType = CaughtType->getPointeeType().getTypePtr();
+
+    if (NeedsCast) { // CaughtType && CaughtType->isRecordType() &&
+                     // It->isRecordType()) {
+      const Record *CaughtRecord =
+          S.getContext().getRecord(CaughtType->getAsCXXRecordDecl());
+      const Record *ItRecord =
+          S.getContext().getRecord(It->getAsCXXRecordDecl());
+      while (ItRecord != CaughtRecord) {
+        llvm::errs() << It << " / " << CaughtType << '\n';
+        const Record *R = S.getContext().getRecord(It->getAsCXXRecordDecl());
+        assert(R);
+        llvm::errs() << "It record: " << R->getName() << '\n';
+        for (const Record::Base &B : R->bases()) {
+          if (cast<CXXRecordDecl>(ItRecord->getDecl())
+                  ->isDerivedFrom(cast<CXXRecordDecl>(
+                      B.Decl))) { //(cast<CXXRecordDecl>(B.Decl)->
+                                  // if (B.R == CaughtRecord) {
+            llvm::errs() << "yay!\n";
+            llvm::errs() << "Casted Value: " << CastedValue << '\n';
+            CastedValue = CastedValue.atField(B.Offset);
+            llvm::errs() << "Casted Value: " << CastedValue << '\n';
+            It = CastedValue.getType().getTypePtr();
+            ItRecord = S.getContext().getRecord(It->getAsCXXRecordDecl());
+            // return true;
+            break;
+          }
+        }
+      }
+    }
+    S.ThrownValue = ThrowValue{Ty, Source, CastedValue, Name};
+  }
+
+  if (Caught) {
+    llvm::errs() << "CAUGHT IN " << F->getName() << '\n';
+    // llvm::errs() << "As\n";
+    // CaughtType->dump();
+  } else {
+    llvm::errs() << "Uncaught exception!\n";
+    // If we didnt' catch the exception in the current frame, save the thrown
+    // value in InterpState to be caught by callers of this function.
+    // const CXXThrowExpr *Source =
+    // cast<CXXThrowExpr>(S.Current->getExpr(OpPC)); S.ThrownValue =
+    // ThrowValue{Ty, Source, ThrownValue, Name};
+    PC = S.Current->getFunction()->getCodeEnd() - align(sizeof(Opcode));
+    llvm::errs() << "Offset now: "
+                 << (PC - S.Current->getFunction()->getCodeBegin()) << '\n';
+    // PC = S.Current->getFunction()->getCodeEnd();// - align(sizeof(Opcode));
+  }
+
+  return true;
+}
+
+inline bool ThrowTrap(InterpState &S, CodePtr OpPC) {
+  llvm::errs() << __PRETTY_FUNCTION__ << '\n';
+  S.ThrowTrapStackSize = S.Stk.size();
+  llvm::errs() << "Trap now: " << S.ThrowTrapStackSize << '\n';
+
+  return true;
+}
+
+/// Allocate memory to store an exception object. This uses the InterpState
+/// allocator, so has the same lifetime as local variables (minus scoping).
+inline bool AllocException(InterpState &S, CodePtr &PC,
+                           const Descriptor *Desc) {
+  llvm::errs() << __PRETTY_FUNCTION__ << '\n';
+
+  assert(Desc);
+  char *Memory = (char *)S.allocate(sizeof(Block) + Desc->getAllocSize());
+  Block *B = new (Memory) Block(~0u, Desc);
+  B->invokeCtor();
+
+  // B->dump();
+
+  S.Stk.push<Pointer>(B);
+  return true;
+}
+
 
//===----------------------------------------------------------------------===//
 // Add, Sub, Mul
 
//===----------------------------------------------------------------------===//
@@ -2204,7 +2462,8 @@ bool Init(InterpState &S, CodePtr OpPC) {
   const Pointer &Ptr = S.Stk.peek<Pointer>();
   if (!CheckInit(S, OpPC, Ptr))
     return false;
-  Ptr.initialize();
+  if (Ptr.canBeInitialized())
+    Ptr.initialize();
   new (&Ptr.deref<T>()) T(Value);
   return true;
 }
@@ -2215,7 +2474,8 @@ bool InitPop(InterpState &S, CodePtr OpPC) {
   const Pointer &Ptr = S.Stk.pop<Pointer>();
   if (!CheckInit(S, OpPC, Ptr))
     return false;
-  Ptr.initialize();
+  if (Ptr.canBeInitialized())
+    Ptr.initialize();
   new (&Ptr.deref<T>()) T(Value);
   return true;
 }
@@ -2565,6 +2825,7 @@ inline bool SubPtr(InterpState &S, CodePtr OpPC, bool 
ElemSizeIsZero) {
 }
 
 inline bool InitScope(InterpState &S, CodePtr OpPC, uint32_t I) {
+  llvm::errs() << __PRETTY_FUNCTION__ << '\n';
   S.Current->initScope(I);
   return true;
 }
@@ -2904,6 +3165,7 @@ inline bool This(InterpState &S, CodePtr OpPC) {
   if (!CheckThis(S, OpPC))
     return false;
   const Pointer &This = S.Current->getThis();
+  llvm::errs() << "This: " << This << '\n';
 
   // Ensure the This pointer has been cast to the correct base.
   if (!This.isDummy()) {
@@ -2912,8 +3174,10 @@ inline bool This(InterpState &S, CodePtr OpPC) {
       [[maybe_unused]] const Record *R = This.getRecord();
       if (!R)
         R = This.narrow().getRecord();
-      if (!R)
+      if (!R) {
+        llvm::errs() << "NO THIS RECORD\n";
         return false;
+      }
       assert(R->getDecl() ==
              cast<CXXMethodDecl>(S.Current->getFunction()->getDecl())
                  ->getParent());
@@ -3144,6 +3408,30 @@ PRESERVE_NONE inline bool NoRet(InterpState &S, CodePtr 
OpPC) {
   S.FFDiag(EndLoc, diag::note_constexpr_no_return);
   return false;
 }
+PRESERVE_NONE inline bool AfterRet(InterpState &S, CodePtr &PC) {
+  llvm::errs() << __PRETTY_FUNCTION__ << '\n';
+
+  if (S.ThrownValue) {
+    while (S.Stk.size() != S.Current->getFrameOffset())
+      S.Stk.discardSlow();
+  }
+
+  assert(S.Current->getFrameOffset() == S.Stk.size() && "Invalid frame");
+
+  if (!S.checkingPotentialConstantExpression() || S.Current->Caller)
+    cleanupAfterFunctionCall(S, PC, S.Current->getFunction());
+
+  if (InterpFrame *Caller = S.Current->Caller) {
+    PC = S.Current->getRetPC();
+    InterpFrame::free(S.Current);
+    S.Current = Caller;
+  } else {
+    InterpFrame::free(S.Current);
+    S.Current = nullptr;
+  }
+
+  return true;
+}
 
 
//===----------------------------------------------------------------------===//
 // NarrowPtr, ExpandPtr
@@ -3776,6 +4064,23 @@ inline bool CheckDestruction(InterpState &S, CodePtr 
OpPC) {
   return CheckDestructor(S, OpPC, Ptr);
 }
 
+template <PrimType Name, class T = typename PrimConv<Name>::T>
+bool GetExceptionValue(InterpState &S, CodePtr OpPC) {
+  llvm::errs() << __PRETTY_FUNCTION__ << '\n';
+  assert(S.ThrownValue);
+
+  S.Stk.push<T>(std::get<T>(S.ThrownValue->Value));
+  S.ThrownValue = std::nullopt;
+  return true;
+}
+
+inline bool ClearExceptionValue(InterpState &S, CodePtr OpPC) {
+  llvm::errs() << __PRETTY_FUNCTION__ << '\n';
+  assert(S.ThrownValue);
+  S.ThrownValue = std::nullopt;
+  return true;
+}
+
 
//===----------------------------------------------------------------------===//
 // Read opcode arguments
 
//===----------------------------------------------------------------------===//
diff --git a/clang/lib/AST/ByteCode/InterpBuiltin.cpp 
b/clang/lib/AST/ByteCode/InterpBuiltin.cpp
index e7b3ef6ce1510..8a18482f5b5ff 100644
--- a/clang/lib/AST/ByteCode/InterpBuiltin.cpp
+++ b/clang/lib/AST/ByteCode/InterpBuiltin.cpp
@@ -4189,6 +4189,15 @@ static bool interp__builtin_ia32_gfni_mul(InterpState 
&S, CodePtr OpPC,
   return true;
 }
 
+static bool interp__builtin_current_exception(InterpState &S, CodePtr OpPC,
+                                              const CallExpr *Call) {
+  // llvm::errs() <<__PRETTY_FUNCTION__ << '\n';
+  // Call->dumpColor();
+
+  S.Stk.push<Pointer>();
+  return true;
+}
+
 bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const CallExpr *Call,
                       uint32_t BuiltinID) {
   if (!S.getASTContext().BuiltinInfo.isConstantEvaluated(BuiltinID))
@@ -6050,6 +6059,8 @@ bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const 
CallExpr *Call,
         },
         /*IsScalar=*/true);
 
+  case Builtin::BI__builtin_current_exception:
+    return interp__builtin_current_exception(S, OpPC, Call);
   default:
     S.FFDiag(S.Current->getLocation(OpPC),
              diag::note_invalid_subexpr_in_const_expr)
diff --git a/clang/lib/AST/ByteCode/InterpFrame.h 
b/clang/lib/AST/ByteCode/InterpFrame.h
index 8b4da6a14de70..0f5992bda9189 100644
--- a/clang/lib/AST/ByteCode/InterpFrame.h
+++ b/clang/lib/AST/ByteCode/InterpFrame.h
@@ -102,6 +102,7 @@ class InterpFrame final : public Frame {
 
   /// Mutates a local variable.
   template <typename T> void setLocal(unsigned Offset, const T &Value) {
+    // assert(localInlineDesc(Offset)->Desc->isPrimitive());
     localRef<T>(Offset) = Value;
     localInlineDesc(Offset)->IsInitialized = true;
   }
diff --git a/clang/lib/AST/ByteCode/InterpStack.cpp 
b/clang/lib/AST/ByteCode/InterpStack.cpp
index 992546560eec4..26c37796b125d 100644
--- a/clang/lib/AST/ByteCode/InterpStack.cpp
+++ b/clang/lib/AST/ByteCode/InterpStack.cpp
@@ -94,6 +94,12 @@ void InterpStack::shrink(size_t Size) {
   StackSize -= Size;
 }
 
+void InterpStack::discardSlow() {
+  assert(!empty());
+
+  TYPE_SWITCH(ItemTypes.back(), { discard<T>(); });
+}
+
 void InterpStack::dump() const {
   llvm::errs() << "Items: " << ItemTypes.size() << ". Size: " << size() << 
'\n';
   if (ItemTypes.empty())
diff --git a/clang/lib/AST/ByteCode/InterpStack.h 
b/clang/lib/AST/ByteCode/InterpStack.h
index c647dfa6d85ea..67ea5d77aa41b 100644
--- a/clang/lib/AST/ByteCode/InterpStack.h
+++ b/clang/lib/AST/ByteCode/InterpStack.h
@@ -58,6 +58,8 @@ class InterpStack final {
     shrink(aligned_size<T>());
   }
 
+  void discardSlow();
+
   /// Returns a reference to the value on the top of the stack.
   template <typename T> T &peek() const {
     assert(!ItemTypes.empty());
diff --git a/clang/lib/AST/ByteCode/InterpState.h 
b/clang/lib/AST/ByteCode/InterpState.h
index 499a21a094e2c..1f4b6eee0d97b 100644
--- a/clang/lib/AST/ByteCode/InterpState.h
+++ b/clang/lib/AST/ByteCode/InterpState.h
@@ -13,12 +13,17 @@
 #ifndef LLVM_CLANG_AST_INTERP_INTERPSTATE_H
 #define LLVM_CLANG_AST_INTERP_INTERPSTATE_H
 
+#include "Boolean.h"
 #include "Context.h"
 #include "DynamicAllocator.h"
 #include "Floating.h"
 #include "Function.h"
+#include "Integral.h"
+#include "IntegralAP.h"
 #include "InterpFrame.h"
 #include "InterpStack.h"
+#include "MemberPointer.h"
+#include "Pointer.h"
 #include "State.h"
 
 namespace clang {
@@ -32,6 +37,13 @@ struct StdAllocatorCaller {
   explicit operator bool() { return Call; }
 };
 
+struct ThrowValue {
+  const Type *Ty;
+  const Expr *ThrowSite;
+  AnyPrimType Value;
+  PrimType T;
+};
+
 /// Interpreter context.
 class InterpState final : public State, public SourceMapper {
 public:
@@ -140,6 +152,7 @@ class InterpState final : public State, public SourceMapper 
{
   mutable std::optional<llvm::BumpPtrAllocator> Allocator;
 
 public:
+  size_t ThrowTrapStackSize = 0;
   /// Reference to the module containing all bytecode.
   Program &P;
   /// Temporary stack.
@@ -162,6 +175,8 @@ class InterpState final : public State, public SourceMapper 
{
   /// ID identifying this evaluation.
   const unsigned EvalID;
 
+  std::optional<ThrowValue> ThrownValue = std::nullopt;
+
   /// Things needed to do speculative execution.
   SmallVectorImpl<PartialDiagnosticAt> *PrevDiags = nullptr;
 #ifndef NDEBUG
diff --git a/clang/lib/AST/ByteCode/Opcodes.td 
b/clang/lib/AST/ByteCode/Opcodes.td
index 0215cd92966ee..d0f9082f59f54 100644
--- a/clang/lib/AST/ByteCode/Opcodes.td
+++ b/clang/lib/AST/ByteCode/Opcodes.td
@@ -142,6 +142,7 @@ class Opcode {
   string Name = "";
   bit CanReturn = 0;
   bit ChangesPC = 0;
+  bit BothPCs = 0;
   bit HasCustomLink = 0;
   bit HasCustomEval = 0;
   bit HasGroup = 0;
@@ -217,10 +218,37 @@ def RetValue : Opcode {
 def NoRet : Opcode {}
 
 
+/// Exceptions
+def AfterRet : Opcode {
+  let CanReturn = 1;
+}
+
+def Throw : Opcode {
+  let Types = [AllTypeClass];
+  let Args = [ArgTypePtr, ArgBool];
+  let ChangesPC = 1;
+  let HasGroup = 1;
+}
+
+def GetExceptionValue : Opcode {
+  let Types = [AllTypeClass];
+  let HasGroup = 1;
+}
+
+def ClearExceptionValue : Opcode;
+
+def AllocException : Opcode {
+  let Args = [ArgDesc];
+}
+
+def ThrowTrap : Opcode;
+
+
 def Call : Opcode {
   let Args = [ArgFunction, ArgUint32];
+  let ChangesPC = 1;
+  let BothPCs = 1;
 }
-
 def CallVirt : Opcode {
   let Args = [ArgFunction, ArgUint32];
 }
@@ -229,6 +257,8 @@ def CallBI : Opcode { let Args = [ArgCallExpr, ArgUint32]; }
 
 def CallPtr : Opcode {
   let Args = [ArgUint32, ArgCallExpr];
+  let ChangesPC = 1;
+  let BothPCs = 1;
 }
 
 def CallVar : Opcode {
diff --git a/clang/lib/AST/ByteCode/PrimType.h 
b/clang/lib/AST/ByteCode/PrimType.h
index 2fa553b7b4a47..e6a65c9297fa1 100644
--- a/clang/lib/AST/ByteCode/PrimType.h
+++ b/clang/lib/AST/ByteCode/PrimType.h
@@ -17,6 +17,7 @@
 #include <climits>
 #include <cstddef>
 #include <cstdint>
+#include <variant>
 
 namespace clang {
 namespace interp {
@@ -48,6 +49,14 @@ enum PrimType : uint8_t {
   PT_MemberPtr = 14,
 };
 
+// Alias for using any one of our primitive types.
+using AnyPrimType =
+    std::variant<Integral<8, true>, Integral<8, false>, Integral<16, true>,
+                 Integral<16, false>, Integral<32, true>, Integral<32, false>,
+                 Integral<64, true>, Integral<64, false>, IntegralAP<true>,
+                 IntegralAP<false>, Boolean, FixedPoint, Floating, Pointer,
+                 MemberPointer>;
+
 constexpr bool isIntegerOrBoolType(PrimType T) { return T <= PT_Bool; }
 constexpr bool isIntegerType(PrimType T) { return T <= PT_IntAPS; }
 
diff --git a/clang/lib/AST/ByteCode/Source.h b/clang/lib/AST/ByteCode/Source.h
index 56ca197e66473..464c1c8bc9811 100644
--- a/clang/lib/AST/ByteCode/Source.h
+++ b/clang/lib/AST/ByteCode/Source.h
@@ -36,6 +36,8 @@ class CodePtr final {
     return *this;
   }
 
+  CodePtr operator+(int32_t Offset) { return CodePtr(Ptr + Offset); }
+
   int32_t operator-(const CodePtr &RHS) const {
     assert(Ptr != nullptr && RHS.Ptr != nullptr && "Invalid code pointer");
     return Ptr - RHS.Ptr;
diff --git a/clang/test/AST/ByteCode/cxx20.cpp 
b/clang/test/AST/ByteCode/cxx20.cpp
index 9800fe01fcaf5..300dc0f02591e 100644
--- a/clang/test/AST/ByteCode/cxx20.cpp
+++ b/clang/test/AST/ByteCode/cxx20.cpp
@@ -1,5 +1,5 @@
-// RUN: %clang_cc1 -fcxx-exceptions -std=c++20 -verify=both,expected 
-fcxx-exceptions %s -DNEW_INTERP -fexperimental-new-constant-interpreter
-// RUN: %clang_cc1 -fcxx-exceptions -std=c++20 -verify=both,ref      
-fcxx-exceptions %s
+// RUN: %clang_cc1 -fcxx-exceptions -std=c++20 -verify=both,expected %s 
-DNEW_INTERP -fexperimental-new-constant-interpreter
+// RUN: %clang_cc1 -fcxx-exceptions -std=c++20 -verify=both,ref      %s
 
 void test_alignas_operand() {
   alignas(8) char dummy;
@@ -654,7 +654,7 @@ namespace ConstexprArrayInitLoopExprDestructors
   struct Highlander {
       int *p = 0;
       constexpr Highlander() {}
-      constexpr void set(int *p) { this->p = p; ++*p; if (*p != 1) throw 
"there can be only one"; }
+      constexpr void set(int *p) { this->p = p; ++*p; if (*p != 1) 
__builtin_abort(); }
       constexpr ~Highlander() { --*p; }
   };
 
@@ -757,7 +757,7 @@ namespace FailingDestructor {
 
     constexpr ~D() {
       if (!can_destroy)
-        throw "oh no";
+        __builtin_abort();
     }
   };
   template<D d>
@@ -1043,7 +1043,7 @@ namespace OnePastEndDtor {
 namespace Virtual {
   struct NonZeroOffset { int padding = 123; };
 
-  constexpr void assert(bool b) { if (!b) throw 0; }
+  constexpr void assert(bool b) { if (!b) __builtin_abort(); }
 
   // Ensure that we pick the right final overrider during construction.
   struct A {
@@ -1172,9 +1172,8 @@ namespace DiscardedTrivialCXXConstructExpr {
     int x;
   };
 
-  constexpr int foo(int x) { // ref-error {{never produces a constant 
expression}}
-    throw S(3); // both-note {{not valid in a constant expression}} \
-                // ref-note {{not valid in a constant expression}}
+  constexpr int foo(int x) { // both-error {{never produces a constant 
expression}}
+    __builtin_abort(); // both-note 2{{not valid in a constant expression}}
     return 1;
   }
 
diff --git a/clang/test/AST/ByteCode/cxx23.cpp 
b/clang/test/AST/ByteCode/cxx23.cpp
index a1aecf329327a..111b7f88eaa29 100644
--- a/clang/test/AST/ByteCode/cxx23.cpp
+++ b/clang/test/AST/ByteCode/cxx23.cpp
@@ -129,8 +129,8 @@ namespace StaticOperators {
 
   struct S1 {
     constexpr S1() { // all20-error {{never produces a constant expression}}
-      throw; // all-note {{not valid in a constant expression}} \
-             // all20-note {{not valid in a constant expression}}
+      __builtin_abort(); // all-note {{not valid in a constant expression}} \
+                         // all20-note {{not valid in a constant expression}}
     }
     static constexpr int operator()() { return 3; } // ref20-warning {{C++23 
extension}} \
                                                     // expected20-warning 
{{C++23 extension}}
diff --git a/clang/test/AST/ByteCode/exceptions.cpp 
b/clang/test/AST/ByteCode/exceptions.cpp
new file mode 100644
index 0000000000000..e390b42aa88ce
--- /dev/null
+++ b/clang/test/AST/ByteCode/exceptions.cpp
@@ -0,0 +1,705 @@
+// RUN: %clang_cc1 -fcxx-exceptions -std=c++26 
-fexperimental-new-constant-interpreter -verify %s
+
+namespace std {
+  class exception {
+  public:
+    constexpr exception() noexcept {};
+    // constexpr exception(const exception&) noexcept;
+    // constexpr exception& operator=(const exception&) noexcept;
+    constexpr virtual ~exception() {};
+    // constexpr virtual const char* what() const noexcept;
+  };
+};
+
+
+class Bad : std::exception {};
+
+namespace Simple {
+  constexpr int a() {
+    try {
+    } catch(int e){
+      return 12;
+    }
+    return -2;
+  }
+  static_assert(a() == -2);
+
+  constexpr int b() {
+    try {
+      throw 12;
+    } catch(int e){
+      return 12;
+    }
+    return -2;
+  }
+  static_assert(b() == 12);
+
+  constexpr int c() {
+    int m = 12;
+    try {
+      throw 12;
+    } catch(int e){
+      m = 140;
+    }
+    return m;
+  }
+  static_assert(c() == 140);
+
+  constexpr int d() {
+    int m = 12;
+    try {
+      throw 12;
+    } catch(int e){
+      m = 140;
+    } catch (float f) {
+      m = 15;
+    }
+    return m;
+  }
+  static_assert(d() == 140);
+
+  constexpr int e() {
+    int m = 12;
+    try {
+      throw 12;
+    } catch(int e){
+      m = e + 2;
+    }
+    return m;
+  }
+  static_assert(e() == 14);
+
+  constexpr int f() {
+    int m = 12;
+    try {
+      throw 12;
+    } catch(...){
+      m = 100;
+    }
+    return m;
+  }
+  static_assert(f() == 100);
+
+  constexpr int g() {
+    int m = 12;
+    try {
+      throw Bad();
+    } catch(Bad &B){
+      m = 100;
+    }
+    return m;
+  }
+  static_assert(g() == 100);
+
+  constexpr int h() {
+    int m = 12;
+    try {
+      throw ++m;
+    } catch(...){
+    }
+    return m;
+  }
+  static_assert(h() == 13);
+
+  constexpr int i(bool b) {
+    try {
+      if (b)
+        throw 12;
+      else
+        throw 14.0f;
+    } catch (int) {
+      return 100;
+    } catch (float) {
+      return 200;
+    }
+    return 0;
+  }
+  static_assert(i(true) == 100);
+  static_assert(i(false) == 200);
+}
+
+namespace Uncaught {
+
+  constexpr int a() {
+    throw 12; // expected-note {{uncaught exception of type 'int': '12'}}
+    return 0;
+  }
+  static_assert(a() == 13); // expected-error {{not an integral constant 
expression}}
+}
+
+namespace NoFrame {
+  static_assert((1, throw 2, 3) == 1); // expected-error {{not an integral 
constant expression}} \
+                                       // expected-warning {{left operand of 
comma operator has no effect}}
+
+}
+
+namespace CleanupAfterThrowingCall {
+  constexpr int a() {
+    throw 12;
+    return -12;
+  }
+  constexpr int test() {
+    try {
+      a();
+    } catch (int i) {
+      return 26;
+    }
+
+    return 120;
+  }
+  static_assert(test() == 26);
+
+  constexpr int b2() {
+    throw 1.0;
+    return 1;
+  }
+  constexpr int a2() {
+    b2();
+    throw 12;
+    return -12;
+  }
+  constexpr int test2() {
+
+    try {
+      a2();
+    } catch (int i) {
+      return 26;
+    } catch (double d ){
+      return (int)(d * 2);
+    }
+
+    return 120;
+  }
+  static_assert(test2() == 2);
+}
+
+namespace Dtors {
+  class Inc {
+    public:
+    int &m;
+    constexpr Inc(int &m) : m(m) {}
+    constexpr ~Inc() { ++m; }
+  };
+
+  constexpr int test1() {
+    int m = 10;
+    Inc _(m);
+
+    try {
+      throw 12;
+    } catch (int) {
+      return m;
+    }
+  }
+  static_assert(test1() == 10);
+
+  constexpr int test2() {
+    int m = 10;
+    try {
+      Inc _(m);
+      throw 12;
+    } catch (int) {
+    }
+    return m;
+  }
+  static_assert(test2() == 11);
+
+  struct checker {
+    int & counter;
+    constexpr ~checker() {
+      ++counter;
+    }
+  };
+
+  constexpr int test() {
+    int counter = 0;
+    {
+      try {
+        auto c1 = checker{counter};
+        throw 42;
+      } catch (...) {
+        return counter * 7;
+      }
+    }
+    return counter * 3;
+  }
+
+  constexpr int destruction_counter = test();
+  static_assert(destruction_counter == 7);
+}
+
+namespace CatchArray {
+  template <typename T> consteval T test(T head, auto... tail) {
+    const T array[] = {head, tail...};
+    try {
+      throw array;
+    } catch (const T (&arr)[5]) {
+      return -2;
+    } catch (const T * ptr) {
+      return *ptr;
+    } catch (...) {
+      return -1;
+    }
+  }
+
+  constexpr auto r0 = test(1,2,3,4,5,6);
+  static_assert(r0 == 1);
+
+  constexpr auto r1 = test(1,2,3,4,5);
+  static_assert(r1 == 1);
+
+  constexpr auto r2 = test(1,2,3,4);
+  static_assert(r2 == 1);
+
+  constexpr auto r3 = test(7,1,2,3,4,5,6);
+  static_assert(r3 == 7);
+
+  constexpr auto r4 = test(8,1,2,3,4,5);
+  static_assert(r4 == 8);
+
+  constexpr auto r5 = test(9,1,2,3,4);
+  static_assert(r5 == 9);
+}
+
+namespace CatchVoidPtr {
+  consteval int test() {
+    int p = 3;
+    try {
+      throw &p;
+    } catch (void * ptr) {
+      return *static_cast<int *>(ptr);
+    }
+  }
+
+  static_assert(test() == 3);
+}
+
+namespace Nullptr {
+  consteval int test_nullptr() {
+    try {
+      throw nullptr;
+    } catch (const int * ex) {
+      return true;
+    } catch (...) {
+      return false;
+    }
+  }
+  static_assert(test_nullptr());
+
+  consteval int test_zero() {
+    try {
+      throw 0;
+    } catch (const int * ex) {
+      return false;
+    } catch (...) {
+      return true;
+    }
+  }
+  static_assert(test_zero());
+}
+
+namespace CatchAll {
+  template <typename T, typename... Args> consteval int test(Args && ... args) 
{
+    try {
+      throw T{args...};
+    } catch (unsigned v) {
+      return static_cast<int>(v) * 2;
+    } catch (int v) {
+      return v * 3;
+    } catch (bool v) {
+      return static_cast<int>(v) * 5;
+    } catch (...) {
+      return -1;
+    }
+    return 0;
+  }
+
+  static_assert(test<unsigned>(42u) == 84);
+  static_assert(test<int>(13) == 39);
+  static_assert(test<bool>(true) == 5);
+  static_assert(test<long>(42) == -1);
+}
+
+namespace Copy {
+  class Child {};
+  constexpr int test() {
+
+    try {
+      throw Child{};
+    } catch (Child C) {
+      return 20;
+    }
+    return 30;
+  }
+  static_assert(test() == 20);
+
+  constexpr int a(){
+      throw Child{};
+  }
+  constexpr int test2() {
+
+    try {
+      a();
+    } catch (Child C) {
+      return 20;
+    }
+    return 30;
+  }
+  static_assert(test2() == 20);
+}
+
+namespace Inheritance {
+  class Parent2 {
+  public:
+    int F = 5;
+    constexpr int getFive() { return F; }
+  };
+  class Parent : public Parent2{
+  };
+  class Child : public Parent {};
+
+  constexpr int foo() {
+    try {
+      throw Child{};
+    } catch (Parent2 P) {
+      return P.getFive() + 9;
+    }
+    return 0;
+  }
+  static_assert(foo() == 14);
+
+  constexpr int foo2() {
+    Child C{};
+    try {
+      throw &C;
+    } catch (Parent2 *P) {
+      return P->getFive() + 12;
+    }
+    return 0;
+  }
+  static_assert(foo2() == 17);
+
+  constexpr int a() {
+    throw Child{};
+  };
+  constexpr int foo3() {
+    try {
+      a();
+    } catch (Parent2 P) {
+      return P.getFive();
+    }
+    return 0;
+  }
+  static_assert(foo3() == 5);
+
+  constexpr int b(Child *C) {
+    throw C;
+  };
+
+  constexpr int foo4() {
+    Child C{};
+    try {
+      b(&C);
+    } catch (Parent *P) {
+      return P->getFive();
+    }
+    return 0;
+  }
+  static_assert(foo4() == 5);
+}
+
+namespace Pointer {
+  static constexpr auto via_const_catch = 2;
+  static constexpr auto via_childs_get_value = 3;
+  static constexpr auto via_special_child_catch = 5;
+
+  struct parent {
+    int value;
+    explicit constexpr parent(int v) noexcept: value{v} { }
+    constexpr virtual int get_value() const noexcept {
+      return value;
+    }
+    constexpr virtual ~parent() = default;
+  };
+
+  struct modifying_child: parent {
+    explicit constexpr modifying_child(int v) noexcept: parent{v} { }
+    constexpr int get_value() const noexcept override {
+      return value * via_childs_get_value;
+    }
+  };
+
+  struct ordinary_child: parent {
+    explicit constexpr ordinary_child(int v) noexcept: parent{v} { }
+  };
+
+  struct special_child: parent {
+    explicit constexpr special_child(int v) noexcept: parent{v} { }
+  };
+
+  consteval int test(void (*fnc)()) {
+    int result = 0;
+    try {
+      fnc();
+    } catch (special_child * sch) {
+      result = sch->get_value() * via_special_child_catch;
+      delete sch;
+    } catch (const special_child * sch) {
+      result = sch->get_value() * via_special_child_catch * via_const_catch;
+      delete sch;
+    } catch (parent * exc) {
+      result = exc->get_value();
+      delete exc;
+    } catch (const parent * exc) {
+      result = exc->get_value() * via_const_catch;
+      delete exc;
+    }
+    return result;
+  }
+
+  constexpr auto r1 = test([] { throw new parent{1}; });
+  static_assert(r1 == 1);
+
+  constexpr auto r2 = test([] { throw new modifying_child{3}; });
+  static_assert(r2 == 3 * via_childs_get_value);
+
+  constexpr auto r3 = test([] { throw new ordinary_child{5}; });
+  static_assert(r3 == 5);
+
+  constexpr auto r4 = test([] { throw new special_child{17}; });
+  static_assert(r4 == 17 * via_special_child_catch);
+}
+
+namespace References1 {
+  class Parent {
+  public:
+    int F = 10;
+    constexpr int getTen() { return F; }
+  };
+
+  class Child : public Parent {
+    public:
+    int F = 5;
+    constexpr int getFive() { return F; }
+
+  };
+
+  constexpr int foo() {
+    try {
+      throw Child{};
+    } catch (Child &C) {
+      return C.getFive();
+    }
+    return 0;
+  }
+  static_assert(foo() == 5);
+
+  constexpr int nested() {
+    throw Child{};
+    return 1;
+  };
+  constexpr int foo2() {
+    try {
+      nested();
+    } catch (Child &C) {
+      return C.getFive();
+    }
+    return 0;
+  }
+  static_assert(foo2() == 5);
+
+  constexpr int foo3() {
+    try {
+      throw Child{};
+    } catch (Parent &P) {
+      return P.getTen();
+    }
+    return 0;
+  }
+  static_assert(foo3() == 10);
+
+  constexpr int foo4() {
+    try {
+      nested();
+    } catch (Parent &P) {
+      return P.getTen();
+    }
+    return 0;
+  }
+  static_assert(foo4() == 10);
+}
+
+namespace References2 {
+  static constexpr auto via_const_catch = 2;
+  static constexpr auto via_childs_get_value = 3;
+  static constexpr auto via_special_child_catch = 5;
+
+  struct parent {
+    int value;
+    explicit constexpr parent(int v) noexcept: value{v} { }
+    constexpr virtual int get_value() const noexcept {
+      return value;
+    }
+    constexpr virtual ~parent() = default;
+  };
+
+  struct modifying_child: parent {
+    explicit constexpr modifying_child(int v) noexcept: parent{v} { }
+    constexpr int get_value() const noexcept override {
+      return value * via_childs_get_value;
+    }
+  };
+
+  struct ordinary_child: parent {
+    explicit constexpr ordinary_child(int v) noexcept: parent{v} { }
+  };
+
+  struct special_child: parent {
+    explicit constexpr special_child(int v) noexcept: parent{v} { }
+  };
+
+  consteval int test(void (*fnc)()) {
+    int result = 0;
+    try {
+      fnc();
+    } catch (special_child & sch) {
+      result = sch.get_value() * via_special_child_catch;
+    } catch (const special_child & sch) {
+      result = sch.get_value() * via_special_child_catch * via_const_catch;
+    } catch (parent & exc) {
+      result = exc.get_value();
+    } catch (const parent & exc) {
+      result = exc.get_value() * via_const_catch;
+    }
+    return result;
+  }
+
+  constexpr auto r1 = test([] { throw parent{1}; });
+  static_assert(r1 == 1);
+
+  constexpr auto r2 = test([] { throw modifying_child{3}; });
+  static_assert(r2 == 3 * via_childs_get_value);
+
+  constexpr auto r3 = test([] { throw ordinary_child{5}; });
+  static_assert(r3 == 5);
+
+  constexpr auto r4 = test([] { throw special_child{17}; });
+  static_assert(r4 == 17 * via_special_child_catch); 
+}
+
+namespace Comma {
+  constexpr int catch_it() {
+    try {
+      return (1, throw 2, 3); // expected-warning {{left operand of comma 
operator has no effect}}
+    } catch (int v) {
+      return v;
+    }
+  }
+  static_assert(catch_it() == 2);
+}
+
+namespace Lifetime {
+  [[noreturn]] constexpr auto create(int v) -> int {
+    throw v; // expected-note {{uncaught exception of type 'int': '42'}} \
+             // expected-note {{uncaught exception of type 'int': '56'}} \
+             // expected-note {{uncaught exception of type 'int': '32'}} \
+             // expected-note {{uncaught exception of type 'int': '4'}} \
+             // expected-note {{uncaught exception of type 'int': '1'}}
+  }
+
+  constexpr int convert(int x) {
+    return x;
+  }
+
+  constexpr auto value1 = convert(create(42)); // expected-error {{must be 
initialized by a constant expression}}
+
+
+  struct wrapper {
+    int value;
+  };
+
+  constexpr auto value2 = wrapper{create(56)}; // expected-error {{must be 
initialized by a constant expression}}
+  constexpr auto value3 = wrapper(create(32)); // expected-error {{must be 
initialized by a constant expression}}
+  constexpr auto value4 = (1,2,3,create(4)); // expected-error {{must be 
initialized by a constant expression}}
+
+  constexpr int fnc() {
+    const auto v = create(1);
+    return v;
+  }
+
+  constexpr auto value5 = fnc(); // expected-error {{must be initialized by a 
constant expression}}
+}
+
+namespace TheWorst {
+  constexpr int zomg() try {
+    throw 12;
+  } catch (int i) {
+    return 13;
+  }
+
+  constexpr int c() {
+    return zomg();
+  }
+  static_assert(c() == 13);
+
+
+  struct hanaxception {
+    int v;
+  };
+
+  struct checker {
+    int value;
+    constexpr checker(int v) try : value{v} {
+      if (v > 10) {
+        throw hanaxception{v};
+      }
+    } catch (const hanaxception h) {
+    }
+  };
+
+  constexpr int test() {
+    auto c = checker{11};
+    return 42;
+  }
+  constexpr int constructor_test = test();
+  static_assert(constructor_test == 42);
+}
+
+namespace Destructors {
+  struct F {
+    constexpr ~F() noexcept(false){
+      throw 42; // expected-note {{uncaught exception of type 'int': '42'}}
+    }
+  };
+  constexpr int test() {
+    try {
+      F f;
+      return 1337;
+    } catch (int i) {
+      return i;
+    }
+
+    return 12;
+  }
+  static_assert(test() == 42);
+
+  constexpr int test2() {
+    F f;
+    return 1337;
+  }
+  static_assert(test2() == 42); // expected-error {{not an integral constant 
expression}}
+
+}
+
+namespace Noexcept {
+  constexpr void throw_exception_here() noexcept(false) {
+    throw 42;
+  }
+
+  constexpr int test() noexcept {
+    throw_exception_here(); // expected-note {{uncaught exception in noexcept 
function}}
+    return 42;
+  }
+  constexpr int value = test(); // expected-error {{must be initialized by a 
constant expression}} \
+                                // expected-note {{in call to}}
+}
diff --git a/clang/test/AST/ByteCode/invalid.cpp 
b/clang/test/AST/ByteCode/invalid.cpp
index 9f157db889a22..207dce44c10b5 100644
--- a/clang/test/AST/ByteCode/invalid.cpp
+++ b/clang/test/AST/ByteCode/invalid.cpp
@@ -1,31 +1,5 @@
-// RUN: %clang_cc1 -triple x86_64 -fcxx-exceptions -std=c++20 
-fexperimental-new-constant-interpreter -verify=expected,both %s
-// RUN: %clang_cc1 -triple x86_64 -fcxx-exceptions -std=c++20                  
                       -verify=ref,both %s
-
-namespace Throw {
-
-  constexpr int ConditionalThrow(bool t) {
-    if (t)
-      throw 4; // both-note {{subexpression not valid in a constant 
expression}}
-
-    return 0;
-  }
-
-  static_assert(ConditionalThrow(false) == 0, "");
-  static_assert(ConditionalThrow(true) == 0, ""); // both-error {{not an 
integral constant expression}} \
-                                                  // both-note {{in call to 
'ConditionalThrow(true)'}}
-
-  constexpr int Throw() { // both-error {{never produces a constant 
expression}}
-    throw 5; // both-note {{subexpression not valid in a constant expression}}
-    return 0;
-  }
-
-  constexpr int NoSubExpr() { // both-error {{never produces a constant 
expression}}
-    throw; // both-note 2{{subexpression not valid}}
-    return 0;
-  }
-  static_assert(NoSubExpr() == 0, ""); // both-error {{not an integral 
constant expression}} \
-                                       // both-note {{in call to}}
-}
+// RUN: %clang_cc1 -triple x86_64 -std=c++20 
-fexperimental-new-constant-interpreter -verify=expected,both %s
+// RUN: %clang_cc1 -triple x86_64 -std=c++20                                   
      -verify=ref,both %s
 
 namespace Asm {
   constexpr int ConditionalAsm(bool t) {
diff --git a/clang/utils/TableGen/ClangOpcodesEmitter.cpp 
b/clang/utils/TableGen/ClangOpcodesEmitter.cpp
index 3192891801ae9..504492feb9e55 100644
--- a/clang/utils/TableGen/ClangOpcodesEmitter.cpp
+++ b/clang/utils/TableGen/ClangOpcodesEmitter.cpp
@@ -127,6 +127,7 @@ void 
ClangOpcodesEmitter::EmitInterpFnDispatchers(raw_ostream &OS, StringRef N,
     bool CanReturn = R->getValueAsBit("CanReturn");
     const auto &Args = R->getValueAsListOfDefs("Args");
     bool ChangesPC = R->getValueAsBit("ChangesPC");
+    bool BothPCs = R->getValueAsBit("BothPCs");
 
     if (Args.empty()) {
       if (CanReturn) {
@@ -152,7 +153,7 @@ void 
ClangOpcodesEmitter::EmitInterpFnDispatchers(raw_ostream &OS, StringRef N,
 
     OS << "  {\n";
 
-    if (!ChangesPC)
+    if (!ChangesPC || BothPCs)
       OS << "    CodePtr OpPC = PC;\n";
 
     // Emit calls to read arguments.
@@ -171,9 +172,11 @@ void 
ClangOpcodesEmitter::EmitInterpFnDispatchers(raw_ostream &OS, StringRef N,
     OS << "    if (!" << N;
     PrintTypes(OS, TS);
     OS << "(S";
-    if (ChangesPC)
+    if (ChangesPC) {
       OS << ", PC";
-    else
+      if (BothPCs)
+        OS << ", OpPC";
+    } else
       OS << ", OpPC";
     for (size_t I = 0, N = Args.size(); I < N; ++I)
       OS << ", V" << I;
@@ -407,6 +410,7 @@ void ClangOpcodesEmitter::EmitEval(raw_ostream &OS, 
StringRef N,
                 OS << (AsRef ? "const " : " ") << Name << " "
                    << (AsRef ? "&" : "") << "A" << I << ", ";
               }
+              bool BothPCs = R->getValueAsBit("BothPCs");
               OS << "SourceInfo L) {\n";
               OS << "  if (!isActive()) return true;\n";
               OS << "  CurrentSource = L;\n";
@@ -414,6 +418,8 @@ void ClangOpcodesEmitter::EmitEval(raw_ostream &OS, 
StringRef N,
               OS << "  return " << N;
               PrintTypes(OS, TS);
               OS << "(S, OpPC";
+              if (BothPCs)
+                OS << ", OpPC";
               for (size_t I = 0, N = Args.size(); I < N; ++I)
                 OS << ", A" << I;
               OS << ");\n";

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