[clang][Interp] Implement __builtin_offsetof

[tbaeder]

Summary

Put all the index expressions on the stack and cast them to SInt64. Then add a new OffsetOf opcode so we can evaluate the index expressions.

[cor3ntin]

clang/lib/AST/Interp/ByteCodeExprGen.cpp

1500–1501

Shouldn't that be size_t?

clang/lib/AST/Interp/Interp.h

1913

Might be useful to use a small vector here

clang/lib/AST/Interp/InterpBuiltin.cpp

589

This function is the same as IntExprEvaluator::VisitOffsetOfExpr - except for the array case. It's frustrating me but I don't have a good solution

[cor3ntin]

clang/lib/AST/Interp/Interp.h

1914

can you use size_t here?
It's already a bug nest but it can't hurt to use better types, even if getNumExpressions returns unsigned
https://godbolt.org/z/vhYxose4o

[tbaeder]

clang/lib/AST/Interp/ByteCodeExprGen.cpp

1500–1501

The point of the conversion is that we later know the type, i.e. it will be an int64 and we can count on that in OffsetOf(). If we don't do this, we'd have to classify() while interpreting, which is also a possibility.

[tbaeder]

Ping

[tbaeder]

Ping

[cor3ntin]

Generally looks good but still a few unaddressed comments

clang/lib/AST/Interp/ByteCodeExprGen.cpp

1500–1501

I'm happy leaving that as is.

[cor3ntin]

LGTM, thanks

clang/lib/AST/Interp/ByteCodeExprGen.h

public:
   bool VisitTypeTraitExpr(const TypeTraitExpr *E);
   bool VisitLambdaExpr(const LambdaExpr *E);
   bool VisitPredefinedExpr(const PredefinedExpr *E);
   bool VisitCXXThrowExpr(const CXXThrowExpr *E);
   bool VisitCXXReinterpretCastExpr(const CXXReinterpretCastExpr *E);
   bool VisitCXXNoexceptExpr(const CXXNoexceptExpr *E);
   bool VisitCXXConstructExpr(const CXXConstructExpr *E);
   bool VisitSourceLocExpr(const SourceLocExpr *E);
+  bool VisitOffsetOfExpr(const OffsetOfExpr *E);
 
 protected:
   bool visitExpr(const Expr *E) override;
   bool visitDecl(const VarDecl *VD) override;
 
 protected:
   /// Emits scope cleanup instructions.
   void emitCleanup();

clang/lib/AST/Interp/ByteCodeExprGen.cpp

bool ByteCodeExprGen<Emitter>::VisitSourceLocExpr(const SourceLocExpr *E) {
   }
   // Otherwise, the APValue is an LValue, with only one element.
   // Theoretically, we don't need the APValue at all of course.
   assert(E->getType()->isPointerType());
   assert(Val.isLValue());
   const APValue::LValueBase &Base = Val.getLValueBase();
   if (const Expr *LValueExpr = Base.dyn_cast<const Expr *>())
     return this->visit(LValueExpr);
 
   // Otherwise, we have a decl (which is the case for
   // __builtin_source_location).
   assert(Base.is<const ValueDecl *>());
   assert(Val.getLValuePath().size() == 0);
   const auto *BaseDecl = Base.dyn_cast<const ValueDecl *>();
   assert(BaseDecl);
 
   auto *UGCD = cast<UnnamedGlobalConstantDecl>(BaseDecl);
 
for (unsigned I = 0, N = R->getNumFields(); I != N; ++I) {
     if (!this->emitInitField(FieldT, F->Offset, E))
       return false;
   }
 
   // Leave the pointer to the global on the stack.
   return true;
 }
 
+template <class Emitter>
+bool ByteCodeExprGen<Emitter>::VisitOffsetOfExpr(const OffsetOfExpr *E) {
+  unsigned N = E->getNumComponents();
+  if (N == 0)
+    return false;
+
+  for (unsigned I = 0; I != N; ++I) {
+    const OffsetOfNode &Node = E->getComponent(I);
+    if (Node.getKind() == OffsetOfNode::Array) {
+      const Expr *ArrayIndexExpr = E->getIndexExpr(Node.getArrayExprIndex());
+      PrimType IndexT = classifyPrim(ArrayIndexExpr->getType());
+
+      if (DiscardResult) {
+        if (!this->discard(ArrayIndexExpr))
+          return false;
+        continue;
+      }
+
+      if (!this->visit(ArrayIndexExpr))
+        return false;
+      // Cast to Sint64.
+      if (IndexT != PT_Sint64) {
+        if (!this->emitCast(IndexT, PT_Sint64, E))
+          return false;
+      }
+    }
+  }
+
+  if (DiscardResult)
+    return true;
+
+  PrimType T = classifyPrim(E->getType());
+  return this->emitOffsetOf(T, E, E);
+}
+
 template <class Emitter> bool ByteCodeExprGen<Emitter>::discard(const Expr *E) {
   if (E->containsErrors())
     return false;
 
   OptionScope<Emitter> Scope(this, /*NewDiscardResult=*/true,
                              /*NewInitializing=*/false);
   return this->Visit(E);
 }

clang/lib/AST/Interp/Interp.h

 
 /// Interpreter entry point.
 bool Interpret(InterpState &S, APValue &Result);
 
 /// Interpret a builtin function.
 bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const Function *F,
                       const CallExpr *Call);
 
+bool InterpretOffsetOf(InterpState &S, CodePtr OpPC, const OffsetOfExpr *E,
+                       llvm::ArrayRef<int64_t> ArrayIndices, int64_t &Result);
+
 /// Perform a bitcast of all fields of P into Buff. This performs the
 /// actions of a __builtin_bit_cast expression when the target type
 /// is primitive.
 bool DoBitCast(InterpState &S, CodePtr OpPC, const Pointer &P, std::byte *Buff,
                size_t BuffSize, unsigned &IndeterminateBits);
 
 /// Perform a bitcast of all fields of P into the fields of DestPtr.
 /// This performs the actions of a __builtin_bit_cast expression when

 /// Same here, but only for casts.
 inline bool InvalidCast(InterpState &S, CodePtr OpPC, CastKind Kind) {
   const SourceLocation &Loc = S.Current->getLocation(OpPC);
   S.FFDiag(Loc, diag::note_constexpr_invalid_cast)
       << static_cast<unsigned>(Kind) << S.Current->getRange(OpPC);
   return false;
 }
 
+template <PrimType Name, class T = typename PrimConv<Name>::T>
+inline bool OffsetOf(InterpState &S, CodePtr OpPC, const OffsetOfExpr *E) {
+  llvm::SmallVector<int64_t> ArrayIndices;
+  for (size_t I = 0; I != E->getNumExpressions(); ++I)
+    ArrayIndices.emplace_back(S.Stk.pop<int64_t>());
+
+  int64_t Result;
+  if (!InterpretOffsetOf(S, OpPC, E, ArrayIndices, Result))
+    return false;
+
+  S.Stk.push<T>(T::from(Result));
+
+  return true;
+}
+
 //===----------------------------------------------------------------------===//
 // Read opcode arguments
 //===----------------------------------------------------------------------===//
 
 template <typename T> inline T ReadArg(InterpState &S, CodePtr &OpPC) {
   if constexpr (std::is_pointer<T>::value) {
     uint32_t ID = OpPC.read<uint32_t>();
     return reinterpret_cast<T>(S.P.getNativePointer(ID));

clang/lib/AST/Interp/InterpBuiltin.cpp

 //===--- InterpBuiltin.cpp - Interpreter for the constexpr VM ---*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 #include "Boolean.h"
 #include "Interp.h"
 #include "PrimType.h"
+#include "clang/AST/RecordLayout.h"
 #include "clang/Basic/Builtins.h"
 #include "clang/Basic/TargetInfo.h"
 
 namespace clang {
 namespace interp {
 
 template <typename T>
 static T getParam(const InterpFrame *Frame, unsigned Index) {
bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const Function *F,
 
   default:
     return false;
   }
 
   return false;
 }
 
+bool InterpretOffsetOf(InterpState &S, CodePtr OpPC, const OffsetOfExpr *E,
+                       llvm::ArrayRef<int64_t> ArrayIndices,
+                       int64_t &IntResult) {
+  CharUnits Result;
+  unsigned N = E->getNumComponents();
+  assert(N > 0);
+
+  unsigned ArrayIndex = 0;
+  QualType CurrentType = E->getTypeSourceInfo()->getType();
+  for (unsigned I = 0; I != N; ++I) {
+    const OffsetOfNode &Node = E->getComponent(I);
+    switch (Node.getKind()) {
+    case OffsetOfNode::Field: {
+      const FieldDecl *MemberDecl = Node.getField();
+      const RecordType *RT = CurrentType->getAs<RecordType>();
+      if (!RT)
+        return false;
+      RecordDecl *RD = RT->getDecl();
+      if (RD->isInvalidDecl())
+        return false;
+      const ASTRecordLayout &RL = S.getCtx().getASTRecordLayout(RD);
+      unsigned FieldIndex = MemberDecl->getFieldIndex();
+      assert(FieldIndex < RL.getFieldCount() && "offsetof field in wrong type");
+      Result += S.getCtx().toCharUnitsFromBits(RL.getFieldOffset(FieldIndex));
+      CurrentType = MemberDecl->getType().getNonReferenceType();
+      break;
+    }
+    case OffsetOfNode::Array: {
+      // When generating bytecode, we put all the index expressions as Sint64 on
+      // the stack.
+      int64_t Index = ArrayIndices[ArrayIndex];
+      const ArrayType *AT = S.getCtx().getAsArrayType(CurrentType);
+      if (!AT)
+        return false;
+      CurrentType = AT->getElementType();
+      CharUnits ElementSize = S.getCtx().getTypeSizeInChars(CurrentType);
+      Result += Index * ElementSize;
+      ++ArrayIndex;
+      break;
+    }
+    case OffsetOfNode::Base: {
+      const CXXBaseSpecifier *BaseSpec = Node.getBase();
+      if (BaseSpec->isVirtual())
+        return false;
+
+      // Find the layout of the class whose base we are looking into.
+      const RecordType *RT = CurrentType->getAs<RecordType>();
+      if (!RT)
+        return false;
+      const RecordDecl *RD = RT->getDecl();
+      if (RD->isInvalidDecl())
+        return false;
+      const ASTRecordLayout &RL = S.getCtx().getASTRecordLayout(RD);
+
+      // Find the base class itself.
+      CurrentType = BaseSpec->getType();
+      const RecordType *BaseRT = CurrentType->getAs<RecordType>();
+      if (!BaseRT)
+        return false;
+
+      // Add the offset to the base.
+      Result += RL.getBaseClassOffset(cast<CXXRecordDecl>(BaseRT->getDecl()));
+      break;
+    }
+    case OffsetOfNode::Identifier:
+      llvm_unreachable("Dependent OffsetOfExpr?");
+    }
+  }
+
+  IntResult = Result.getQuantity();
+
+  return true;
+}
+
 } // namespace interp
 } // namespace clang

clang/lib/AST/Interp/Opcodes.td

 def ArgFunction : ArgType { let Name = "const Function *"; }
 def ArgRecordDecl : ArgType { let Name = "const RecordDecl *"; }
 def ArgRecordField : ArgType { let Name = "const Record::Field *"; }
 def ArgFltSemantics : ArgType { let Name = "const llvm::fltSemantics *"; }
 def ArgRoundingMode : ArgType { let Name = "llvm::RoundingMode"; }
 def ArgLETD: ArgType { let Name = "const LifetimeExtendedTemporaryDecl *"; }
 def ArgCastKind : ArgType { let Name = "CastKind"; }
 def ArgCallExpr : ArgType { let Name = "const CallExpr *"; }
+def ArgOffsetOfExpr : ArgType { let Name = "const OffsetOfExpr *"; }
 
 //===----------------------------------------------------------------------===//
 // Classes of types instructions operate on.
 //===----------------------------------------------------------------------===//
 
 class TypeClass {
   list<Type> Types;
 }
def CallBI : Opcode {
   let Types = [];
 }
 
 def CallPtr : Opcode {
   let Args = [];
   let Types = [];
 }
 
+def OffsetOf : Opcode {
+  let Types = [IntegerTypeClass];
+  let Args = [ArgOffsetOfExpr];
+  let HasGroup = 1;
+}
+
 //===----------------------------------------------------------------------===//
 // Frame management
 //===----------------------------------------------------------------------===//
 
 // [] -> []
 def Destroy : Opcode {
   let Args = [ArgUint32];
   let HasCustomEval = 1;

clang/test/AST/Interp/class-layout.cpp

-// RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -fexperimental-new-constant-interpreter -std=c++98 -Wno-inaccessible-base -Wno-c++11-extensions
-// RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -fexperimental-new-constant-interpreter -std=c++11 -Wno-inaccessible-base
-// RUN: %clang_cc1 -triple x86_64-apple-darwin    %s -fsyntax-only -verify -fexperimental-new-constant-interpreter -std=c++11 -Wno-inaccessible-base -DCLANG_ABI_COMPAT=15
-// RUN: %clang_cc1 -triple x86_64-scei-ps4        %s -fsyntax-only -verify -fexperimental-new-constant-interpreter -std=c++11 -Wno-inaccessible-base -DCLANG_ABI_COMPAT=6
-// RUN: %clang_cc1 -triple x86_64-sie-ps5         %s -fsyntax-only -verify -fexperimental-new-constant-interpreter -std=c++11 -Wno-inaccessible-base -DCLANG_ABI_COMPAT=6
-// RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -fexperimental-new-constant-interpreter -std=c++11 -Wno-inaccessible-base -fclang-abi-compat=6 -DCLANG_ABI_COMPAT=6
-// RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -fexperimental-new-constant-interpreter -std=c++11 -Wno-inaccessible-base -fclang-abi-compat=14 -DCLANG_ABI_COMPAT=14
-// RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -fexperimental-new-constant-interpreter -std=c++11 -Wno-inaccessible-base -fclang-abi-compat=15 -DCLANG_ABI_COMPAT=15
-// RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -fexperimental-new-constant-interpreter -std=c++11 -Wno-inaccessible-base -fclang-abi-compat=16 -DCLANG_ABI_COMPAT=16
-// expected-no-diagnostics
-
-// FIXME: This is a copy of clang/test/SemaCXX/class-layout.cpp, but with the
-//   __builtin_offsetof calls commented out. Once that is supported in the
-//   new interpreter, we might as well remove this duplicated file and
-//   just use the one in SemaCXX/.
-
-#define SA(n, p) int a##n[(p) ? 1 : -1]
-
-struct A {
-  int a;
-  char b;
-};
-
-SA(0, sizeof(A) == 8);
-
-struct B : A {
-  char c;
-};
-
-SA(1, sizeof(B) == 12);
-
-struct C {
-// Make fields private so C won't be a POD type.
-private:
-  int a;
-  char b;
-};
-
-SA(2, sizeof(C) == 8);
-
-struct D : C {
-  char c;
-};
-
-SA(3, sizeof(D) == 8);
-
-struct __attribute__((packed)) E {
-  char b;
-  int a;
-};
-
-SA(4, sizeof(E) == 5);
-
-struct __attribute__((packed)) F : E {
-  char d;
-};
-
-SA(5, sizeof(F) == 6);
-
-struct G { G(); };
-struct H : G { };
-
-SA(6, sizeof(H) == 1);
-
-struct I {
-  char b;
-  int a;
-} __attribute__((packed));
-
-SA(6_1, sizeof(I) == 5);
-
-// PR5580
-namespace PR5580 {
-
-class A { bool iv0 : 1; };
-SA(7, sizeof(A) == 1);  
-
-class B : A { bool iv0 : 1; };
-SA(8, sizeof(B) == 2);
-
-struct C { bool iv0 : 1; };
-SA(9, sizeof(C) == 1);  
-
-struct D : C { bool iv0 : 1; };
-SA(10, sizeof(D) == 2);
-
-}
-
-namespace Test1 {
-
-// Test that we don't assert on this hierarchy.
-struct A { };
-struct B : A { virtual void b(); };
-class C : virtual A { int c; };
-struct D : virtual B { };
-struct E : C, virtual D { };
-class F : virtual E { };
-struct G : virtual E, F { };
-
-SA(0, sizeof(G) == 24);
-
-}
-
-namespace Test2 {
-
-// Test that this somewhat complex class structure is laid out correctly.
-struct A { };
-struct B : A { virtual void b(); };
-struct C : virtual B { };
-struct D : virtual A { };
-struct E : virtual B, D { };
-struct F : E, virtual C { };
-struct G : virtual F, A { };
-struct H { G g; };
-
-SA(0, sizeof(H) == 24);
-
-}
-
-namespace PR16537 {
-namespace test1 {
-  struct pod_in_11_only {
-  private:
-    long long x;
-  };
-   
-  struct tail_padded_pod_in_11_only {
-    pod_in_11_only pod11;
-    char tail_padding;
-  };
-    
-  struct might_use_tail_padding : public tail_padded_pod_in_11_only {
-    char may_go_into_tail_padding;
-  };
-
-  SA(0, sizeof(might_use_tail_padding) == 16);
-}
-
-namespace test2 {
-  struct pod_in_11_only {
-  private:
-    long long x;
-  };
-   
-  struct tail_padded_pod_in_11_only {
-    pod_in_11_only pod11 __attribute__((aligned(16)));
-  };
-    
-  struct might_use_tail_padding : public tail_padded_pod_in_11_only {
-    char may_go_into_tail_padding;
-  };
-
-  SA(0, sizeof(might_use_tail_padding) == 16);
-}
-
-namespace test3 {
-  struct pod_in_11_only {
-  private:
-    long long x;
-  };
-   
-  struct tail_padded_pod_in_11_only {
-    pod_in_11_only pod11;
-    char tail_padding;
-  };
-
-  struct second_base {
-      char foo;
-  };
-    
-  struct might_use_tail_padding : public tail_padded_pod_in_11_only, public second_base {
-
-  };
-  SA(0, sizeof(might_use_tail_padding) == 16);
-}
-
-namespace test4 {
-  struct pod_in_11_only {
-  private:
-    long long x;
-  };
-   
-  struct tail_padded_pod_in_11_only {
-    pod_in_11_only pod11;
-    char tail_padding;
-  };
-
-  struct second_base {
-    char foo;
-  };
-    
-  struct might_use_tail_padding : public tail_padded_pod_in_11_only, public second_base {
-    char may_go_into_tail_padding;
-  };
-  SA(0, sizeof(might_use_tail_padding) == 16);
-}
-
-namespace test5 {
-  struct pod_in_11_only {
-  private:
-    long long x;
-  };
-
-  struct pod_in_11_only2 {
-  private:
-    long long x;
-  };
-   
-  struct tail_padded_pod_in_11_only {
-    pod_in_11_only pod11;
-    char tail_padding;
-  };
-
-  struct second_base {
-    pod_in_11_only2 two;
-    char foo;
-  };
-    
-  struct might_use_tail_padding : public tail_padded_pod_in_11_only, public second_base {
-    char may_go_into_tail_padding;
-  };
-  SA(0, sizeof(might_use_tail_padding) == 32);
-}
-
-namespace test6 {
-  struct pod_in_11_only {
-  private:
-    long long x;
-  };
-
-  struct pod_in_11_only2 {
-  private:
-    long long x;
-  };
-   
-  struct tail_padded_pod_in_11_only {
-    pod_in_11_only pod11;
-    char tail_padding;
-  };
-
-  struct second_base {
-    pod_in_11_only2 two;
-    char foo;
-  };
-    
-  struct might_use_tail_padding : public tail_padded_pod_in_11_only, public second_base {
-    char may_go_into_tail_padding;
-  };
-  SA(0, sizeof(might_use_tail_padding) == 32);
-}
-
-namespace test7 {
-  struct pod_in_11_only {
-  private:
-    long long x;
-  };
-   
-  struct tail_padded_pod_in_11_only {
-    pod_in_11_only pod11;
-    pod_in_11_only pod12;
-    char tail_padding;
-  };
-    
-  struct might_use_tail_padding : public tail_padded_pod_in_11_only {
-    char may_go_into_tail_padding;
-  };
-
-  SA(0, sizeof(might_use_tail_padding) == 24);
-}
-
-namespace test8 {
-  struct pod_in_11_only {
-  private:
-    long long x;
-  };
-   
-  struct tail_padded_pod_in_11_only {
-    pod_in_11_only pod11;
-    char tail_padding;
-  };
-
-  struct another_layer {
-    tail_padded_pod_in_11_only pod;
-    char padding;
-  };
-    
-  struct might_use_tail_padding : public another_layer {
-    char may_go_into_tail_padding;
-  };
-
-  SA(0, sizeof(might_use_tail_padding) == 24);
-}
-
-namespace test9 {
-  struct pod_in_11_only {
-  private:
-    long long x;
-  };
-   
-  struct tail_padded_pod_in_11_only {
-    pod_in_11_only pod11;
-    char tail_padding;
-  };
-
-  struct another_layer : tail_padded_pod_in_11_only {
-  };
-    
-  struct might_use_tail_padding : public another_layer {
-    char may_go_into_tail_padding;
-  };
-
-  SA(0, sizeof(might_use_tail_padding) == 16);
-}
-
-namespace test10 {
-  struct pod_in_11_only {
-  private:
-    long long x;
-  };
-   
-  struct A {
-    pod_in_11_only a;
-    char apad;
-  };
-
-  struct B {
-    char b;
-  };
-
-  struct C {
-    pod_in_11_only c;
-    char cpad;
-  };
-
-  struct D {
-    char d;
-  };
-    
-  struct might_use_tail_padding : public A, public B, public C, public D {
-  };
-
-  SA(0, sizeof(might_use_tail_padding) == 32);
-}
-
-namespace test11 {
-  struct pod_in_11_only {
-  private:
-    long long x;
-  };
-   
-  struct A {
-    pod_in_11_only a;
-    char apad;
-  };
-
-  struct B {
-    char b_pre;
-    pod_in_11_only b;
-    char bpad;
-  };
-
-  struct C {
-    char c_pre;
-    pod_in_11_only c;
-    char cpad;
-  };
-
-  struct D {
-    char d_pre;
-    pod_in_11_only d;
-    char dpad;
-  };
-    
-  struct might_use_tail_padding : public A, public B, public C, public D {
-    char m;
-  };
-
-  SA(0, sizeof(might_use_tail_padding) == 88);
-}
-
-namespace test12 {
-  struct pod_in_11_only {
-  private:
-    long long x;
-  };
-   
-  struct A {
-    pod_in_11_only a __attribute__((aligned(128)));
-  };
-
-  struct B {
-    char bpad;
-  };
-
-  struct C {
-    char cpad;
-  };
-
-  struct D {
-    char dpad;
-  };
-    
-  struct might_use_tail_padding : public A, public B, public C, public D {
-    char m;
-  };
-  SA(0, sizeof(might_use_tail_padding) == 128);
-}
-
-namespace test13 {
-  struct pod_in_11_only {
-  private:
-    long long x;
-  };
-   
-  struct A {
-    pod_in_11_only a;
-    char apad;
-  };
-
-  struct B {
-  };
-
-  struct C {
-    char c_pre;
-    pod_in_11_only c;
-    char cpad;
-  };
-
-  struct D {
-  };
-    
-  struct might_use_tail_padding : public A, public B, public C, public D {
-    char m;
-  };
-  SA(0, sizeof(might_use_tail_padding) == 40);
-}
-
-namespace test14 {
-  struct pod_in_11_only {
-  private:
-    long long x;
-  };
-   
-  struct A {
-    pod_in_11_only a;
-    char apad;
-  };
-
-  struct might_use_tail_padding : public A {
-    struct {
-      int : 0;
-    } x;
-  };
-  SA(0, sizeof(might_use_tail_padding) == 16);
-}
-
-namespace test15 {
-  struct pod_in_11_only {
-  private:
-    long long x;
-  };
-   
-  struct A {
-    pod_in_11_only a;
-    char apad;
-  };
-
-  struct might_use_tail_padding : public A {
-    struct {
-      char a:1;
-      char b:2;
-      char c:2;
-      char d:2;
-      char e:1;
-    } x;
-  };
-  SA(0, sizeof(might_use_tail_padding) == 16);
-}
-
-namespace test16 {
-  struct pod_in_11_only {
-  private:
-    long long x;
-  };
-   
-  struct A  {
-    pod_in_11_only a;
-    char apad;
-  };
-
-  struct B {
-    char bpod;
-    pod_in_11_only b;
-    char bpad;
-  };
-
-  struct C : public A, public B {
-  };
-  
-  struct D : public C {
-  };
-
-  struct might_use_tail_padding : public D {
-    char m;
-  };
-  SA(0, sizeof(might_use_tail_padding) == 40);
-}
-
-namespace test17 {
-  struct pod_in_11_only {
-  private:
-    long long x;
-  };
-   
-  struct A {
-    pod_in_11_only a __attribute__((aligned(512)));
-  };
-
-  struct B {
-    char bpad;
-    pod_in_11_only foo;
-    char btail;
-  };
-
-  struct C {
-    char cpad;
-  };
-
-  struct D {
-    char dpad;
-  };
-    
-  struct might_use_tail_padding : public A, public B, public C, public D {
-    char a;
-  };
-  SA(0, sizeof(might_use_tail_padding) == 512);
-}
-
-namespace test18 {
-  struct pod_in_11_only {
-  private:
-    long long x;
-  };
-   
-  struct A  {
-    pod_in_11_only a;
-    char apad;
-  };
-
-  struct B {
-    char bpod;
-    pod_in_11_only b;
-    char bpad;
-  };
-
-  struct A1  {
-    pod_in_11_only a;
-    char apad;
-  };
-
-  struct B1 {
-    char bpod;
-    pod_in_11_only b;
-    char bpad;
-  };
-
-  struct C : public A, public B {
-  };
-
-  struct D : public A1, public B1 {
-  };
-
-  struct E : public D, public C {
-  };
-
-  struct F : public E {
-  };
-
-  struct might_use_tail_padding : public F {
-    char m;
-  };
-  SA(0, sizeof(might_use_tail_padding) == 80);
-}
-} // namespace PR16537
-
-namespace PR37275 {
-  struct X { char c; };
-
-  struct A { int n; };
-  _Static_assert(_Alignof(A) == _Alignof(int), "");
-  _Static_assert(_Alignof(A[]) == _Alignof(A), "");
-
-  _Static_assert(_Alignof(int[]) == _Alignof(int), "");
-  _Static_assert(_Alignof(char[]) == _Alignof(char), "");
-
-  // __attribute__((packed)) does not apply to base classes.
-  struct __attribute__((packed)) B : X, A {};
-#if defined(CLANG_ABI_COMPAT) && CLANG_ABI_COMPAT <= 6
-  _Static_assert(_Alignof(B) == 1, "");
-  _Static_assert(_Alignof(B[]) == 1, "");
-  //_Static_assert(__builtin_offsetof(B, n) == 1, ""); FIXME
-#else
-  _Static_assert(_Alignof(B) == _Alignof(int), "");
-  _Static_assert(_Alignof(B[]) == _Alignof(int), "");
-  //_Static_assert(__builtin_offsetof(B, n) == 4, ""); FIXME
-#endif
-
-  // #pragma pack does, though.
-#pragma pack(push, 2)
-  struct C : X, A {};
-  _Static_assert(_Alignof(C) == 2, "");
-  _Static_assert(_Alignof(C[]) == 2, "");
-  //_Static_assert(__builtin_offsetof(C, n) == 2, ""); FIXME
-
-  struct __attribute__((packed)) D : X, A {};
-#if defined(CLANG_ABI_COMPAT) && CLANG_ABI_COMPAT <= 6
-  _Static_assert(_Alignof(D) == 1, "");
-  //_Static_assert(__builtin_offsetof(D, n) == 1, ""); FIXME
-#else
-  _Static_assert(_Alignof(D) == 2, "");
-  //_Static_assert(__builtin_offsetof(D, n) == 2, ""); FIXME
-#endif
-#pragma pack(pop)
-}
-
-namespace non_pod {
-struct t1 {
-protected:
-  int a;
-};
-// GCC prints warning: ignoring packed attribute because of unpacked non-POD field 't1 t2::v1'`
-struct t2 {
-  char c1;
-  short s1;
-  char c2;
-  t1 v1;
-} __attribute__((packed));
-#if defined(CLANG_ABI_COMPAT) && CLANG_ABI_COMPAT <= 15
-_Static_assert(_Alignof(t1) == 4, "");
-_Static_assert(_Alignof(t1[]) == 4, "");
-_Static_assert(_Alignof(t2) == 1, "");
-_Static_assert(_Alignof(t2[]) == 1, "");
-#else
-_Static_assert(_Alignof(t1) == 4, "");
-_Static_assert(_Alignof(t1[]) == 4, "");
-_Static_assert(_Alignof(t2) == 4, "");
-_Static_assert(_Alignof(t2[]) == 4, "");
-#endif
-_Static_assert(sizeof(t2) == 8, ""); // it's still packing the rest of the struct
-} // namespace non_pod
-
-namespace non_pod_packed {
-struct t1 {
-protected:
-  int a;
-} __attribute__((packed));
-struct t2 {
-  t1 v1;
-} __attribute__((packed));
-_Static_assert(_Alignof(t1) == 1, "");
-_Static_assert(_Alignof(t2) == 1, "");
-} // namespace non_pod_packed
-
-namespace non_pod_packed_packed {
-struct B {
-  int b;
-};
-struct  FromB : B {
-} __attribute__((packed));
-struct C {
-  char a[3];
-  FromB b;
-} __attribute__((packed));
-//_Static_assert(__builtin_offsetof(C, b) == 3, ""); FIXME
-}
-
-namespace cxx11_pod {
-struct t1 {
-  t1() = default;
-  t1(const t1&) = delete;
-  ~t1() = delete;
-  t1(t1&&) = default;
-  int a;
-  char c;
-};
-struct t2 {
-  t1 v1;
-} __attribute__((packed));
-_Static_assert(_Alignof(t2) == 1, "");
-struct t3 : t1 {
-  char c;
-};
-#if defined(CLANG_ABI_COMPAT) && CLANG_ABI_COMPAT <= 15
-_Static_assert(sizeof(t3) == 8, "");
-#else
-_Static_assert(sizeof(t3) == 12, "");
-#endif
-}

clang/test/AST/Interp/literals.cpp

constexpr int ignoredExprs() {
     "a";
     'b';
     sizeof(int);
     alignof(int);
 
     (short)5;
     (bool)1;
     __null;
+    __builtin_offsetof(A, a);
 
     return 0;
   }
   static_assert(ignoredExprs() == 0, "");
 
   constexpr int oh_my(int x) {
     (int){ x++ };
     return x;

clang/test/SemaCXX/class-layout.cpp

 // RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++98 -Wno-inaccessible-base -Wno-c++11-extensions
 // RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base
 // RUN: %clang_cc1 -triple x86_64-apple-darwin    %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -DCLANG_ABI_COMPAT=15
 // RUN: %clang_cc1 -triple x86_64-scei-ps4        %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -DCLANG_ABI_COMPAT=6
 // RUN: %clang_cc1 -triple x86_64-sie-ps5         %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -DCLANG_ABI_COMPAT=6
 // RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -fclang-abi-compat=6 -DCLANG_ABI_COMPAT=6
 // RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -fclang-abi-compat=14 -DCLANG_ABI_COMPAT=14
 // RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -fclang-abi-compat=15 -DCLANG_ABI_COMPAT=15
 // RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -fclang-abi-compat=16 -DCLANG_ABI_COMPAT=16
 // RUN: %clang_cc1 -triple powerpc-ibm-aix7.3.0.0 %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -DCLANG_ABI_COMPAT=15
 // RUN: %clang_cc1 -triple powerpc-ibm-aix7.3.0.0 %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -fclang-abi-compat=15 -DCLANG_ABI_COMPAT=15
 // RUN: %clang_cc1 -triple powerpc64-ibm-aix7.3.0.0 %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -DCLANG_ABI_COMPAT=15
 // RUN: %clang_cc1 -triple powerpc64-ibm-aix7.3.0.0 %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -fclang-abi-compat=15 -DCLANG_ABI_COMPAT=15
 // RUN: %clang_cc1 -triple s390x-none-zos %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base
 // RUN: %clang_cc1 -triple s390x-none-zos %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -fclang-abi-compat=15 -DCLANG_ABI_COMPAT=15
 
+// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++98 -Wno-inaccessible-base -Wno-c++11-extensions
+// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base
+// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -triple x86_64-apple-darwin    %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -DCLANG_ABI_COMPAT=15
+// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -triple x86_64-scei-ps4        %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -DCLANG_ABI_COMPAT=6
+// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -triple x86_64-sie-ps5         %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -DCLANG_ABI_COMPAT=6
+// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -fclang-abi-compat=6 -DCLANG_ABI_COMPAT=6
+// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -fclang-abi-compat=14 -DCLANG_ABI_COMPAT=14
+// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -fclang-abi-compat=15 -DCLANG_ABI_COMPAT=15
+// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -fclang-abi-compat=16 -DCLANG_ABI_COMPAT=16
+// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -triple powerpc-ibm-aix7.3.0.0 %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -DCLANG_ABI_COMPAT=15
+// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -triple powerpc-ibm-aix7.3.0.0 %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -fclang-abi-compat=15 -DCLANG_ABI_COMPAT=15
+// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -triple powerpc64-ibm-aix7.3.0.0 %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -DCLANG_ABI_COMPAT=15
+// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -triple powerpc64-ibm-aix7.3.0.0 %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -fclang-abi-compat=15 -DCLANG_ABI_COMPAT=15
+// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -triple s390x-none-zos %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base
+// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -triple s390x-none-zos %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -fclang-abi-compat=15 -DCLANG_ABI_COMPAT=15
+
+
+
+
 // expected-no-diagnostics
 
 #if !defined(__MVS__) && !defined(_AIX)
 
 #define SA(n, p) int a##n[(p) ? 1 : -1]
 
 struct A {
   int a;

clang/test/SemaCXX/offsetof-0x.cpp

 // RUN: %clang_cc1 -triple x86_64-apple-darwin10.0.0 -fsyntax-only -std=c++11 -verify %s -Winvalid-offsetof
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10.0.0 -fsyntax-only -std=c++11 -verify %s -Winvalid-offsetof -fexperimental-new-constant-interpreter
 
 struct NonPOD {
   virtual void f();
   int m;
 };
 
 struct P {
   NonPOD fieldThatPointsToANonPODType;

clang/test/SemaCXX/offsetof.cpp

 // RUN: %clang_cc1 -triple x86_64-apple-darwin10.0.0 -fsyntax-only -verify %s -Winvalid-offsetof -std=c++98
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10.0.0 -fsyntax-only -verify %s -Winvalid-offsetof -std=c++98 -fexperimental-new-constant-interpreter
 
 struct NonPOD {
   virtual void f();
   int m;
 };
 
 struct P {
   NonPOD fieldThatPointsToANonPODType;