Revert "[MS][clang] Add support for vector deleting destructors (#126240)"

This caused link errors when building with sancov. See comment on the PR.

> Whereas it is UB in terms of the standard to delete an array of objects
> via pointer whose static type doesn't match its dynamic type, MSVC
> supports an extension allowing to do it.
> Aside from array deletion not working correctly in the mentioned case,
> currently not having this extension implemented causes clang to generate
> code that is not compatible with the code generated by MSVC, because
> clang always puts scalar deleting destructor to the vftable. This PR
> aims to resolve these problems.
>
> Fixes https://github.com/llvm/llvm-project/issues/19772

This reverts commit d6942d54f677000cf713d2b0eba57b641452beb4.

1 files changed, 4 insertions, 73 deletions

diff --git a/clang/lib/CodeGen/CGClass.cpp b/clang/lib/CodeGen/CGClass.cpp
index e54fd54..fa69caa4 100644
--- a/clang/lib/CodeGen/CGClass.cpp
+++ b/clang/lib/CodeGen/CGClass.cpp
@@ -1433,70 +1433,6 @@ static bool CanSkipVTablePointerInitialization(CodeGenFunction &CGF,
   return true;
 }
 
-static void EmitConditionalArrayDtorCall(const CXXDestructorDecl *DD,
-                                         CodeGenFunction &CGF,
-                                         llvm::Value *ShouldDeleteCondition) {
-  Address ThisPtr = CGF.LoadCXXThisAddress();
-  llvm::BasicBlock *ScalarBB = CGF.createBasicBlock("dtor.scalar");
-  llvm::BasicBlock *callDeleteBB =
-      CGF.createBasicBlock("dtor.call_delete_after_array_destroy");
-  llvm::BasicBlock *VectorBB = CGF.createBasicBlock("dtor.vector");
-  auto *CondTy = cast<llvm::IntegerType>(ShouldDeleteCondition->getType());
-  llvm::Value *CheckTheBitForArrayDestroy = CGF.Builder.CreateAnd(
-      ShouldDeleteCondition, llvm::ConstantInt::get(CondTy, 2));
-  llvm::Value *ShouldDestroyArray =
-      CGF.Builder.CreateIsNull(CheckTheBitForArrayDestroy);
-  CGF.Builder.CreateCondBr(ShouldDestroyArray, ScalarBB, VectorBB);
-
-  CGF.EmitBlock(VectorBB);
-
-  llvm::Value *numElements = nullptr;
-  llvm::Value *allocatedPtr = nullptr;
-  CharUnits cookieSize;
-  QualType EltTy = DD->getThisType()->getPointeeType();
-  CGF.CGM.getCXXABI().ReadArrayCookie(CGF, ThisPtr, EltTy, numElements,
-                                      allocatedPtr, cookieSize);
-
-  // Destroy the elements.
-  QualType::DestructionKind dtorKind = EltTy.isDestructedType();
-
-  assert(dtorKind);
-  assert(numElements && "no element count for a type with a destructor!");
-
-  CharUnits elementSize = CGF.getContext().getTypeSizeInChars(EltTy);
-  CharUnits elementAlign =
-      ThisPtr.getAlignment().alignmentOfArrayElement(elementSize);
-
-  llvm::Value *arrayBegin = ThisPtr.emitRawPointer(CGF);
-  llvm::Value *arrayEnd = CGF.Builder.CreateInBoundsGEP(
-      ThisPtr.getElementType(), arrayBegin, numElements, "delete.end");
-
-  // We already checked that the array is not 0-length before entering vector
-  // deleting dtor.
-  CGF.emitArrayDestroy(arrayBegin, arrayEnd, EltTy, elementAlign,
-                       CGF.getDestroyer(dtorKind),
-                       /*checkZeroLength*/ false, CGF.needsEHCleanup(dtorKind));
-
-  llvm::BasicBlock *VectorBBCont = CGF.createBasicBlock("dtor.vector.cont");
-  CGF.EmitBlock(VectorBBCont);
-
-  llvm::Value *CheckTheBitForDeleteCall = CGF.Builder.CreateAnd(
-      ShouldDeleteCondition, llvm::ConstantInt::get(CondTy, 1));
-
-  llvm::Value *ShouldCallDelete =
-      CGF.Builder.CreateIsNull(CheckTheBitForDeleteCall);
-  CGF.Builder.CreateCondBr(ShouldCallDelete, CGF.ReturnBlock.getBlock(),
-                           callDeleteBB);
-  CGF.EmitBlock(callDeleteBB);
-  const CXXDestructorDecl *Dtor = cast<CXXDestructorDecl>(CGF.CurCodeDecl);
-  const CXXRecordDecl *ClassDecl = Dtor->getParent();
-  CGF.EmitDeleteCall(Dtor->getOperatorDelete(), allocatedPtr,
-                     CGF.getContext().getTagDeclType(ClassDecl));
-
-  CGF.EmitBranchThroughCleanup(CGF.ReturnBlock);
-  CGF.EmitBlock(ScalarBB);
-}
-
 /// EmitDestructorBody - Emits the body of the current destructor.
 void CodeGenFunction::EmitDestructorBody(FunctionArgList &Args) {
   const CXXDestructorDecl *Dtor = cast<CXXDestructorDecl>(CurGD.getDecl());
@@ -1526,9 +1462,7 @@ void CodeGenFunction::EmitDestructorBody(FunctionArgList &Args) {
   // outside of the function-try-block, which means it's always
   // possible to delegate the destructor body to the complete
   // destructor.  Do so.
-  if (DtorType == Dtor_Deleting || DtorType == Dtor_VectorDeleting) {
-    if (CXXStructorImplicitParamValue && DtorType == Dtor_VectorDeleting)
-      EmitConditionalArrayDtorCall(Dtor, *this, CXXStructorImplicitParamValue);
+  if (DtorType == Dtor_Deleting) {
     RunCleanupsScope DtorEpilogue(*this);
     EnterDtorCleanups(Dtor, Dtor_Deleting);
     if (HaveInsertPoint()) {
@@ -1557,8 +1491,6 @@ void CodeGenFunction::EmitDestructorBody(FunctionArgList &Args) {
   switch (DtorType) {
   case Dtor_Comdat: llvm_unreachable("not expecting a COMDAT");
   case Dtor_Deleting: llvm_unreachable("already handled deleting case");
-  case Dtor_VectorDeleting:
-    llvm_unreachable("already handled vector deleting case");
 
   case Dtor_Complete:
     assert((Body || getTarget().getCXXABI().isMicrosoft()) &&
@@ -1641,6 +1573,7 @@ namespace {
       return CGF.EmitScalarExpr(ThisArg);
     return CGF.LoadCXXThis();
   }
+
   /// Call the operator delete associated with the current destructor.
   struct CallDtorDelete final : EHScopeStack::Cleanup {
     CallDtorDelete() {}
@@ -1659,10 +1592,8 @@ namespace {
                                      bool ReturnAfterDelete) {
     llvm::BasicBlock *callDeleteBB = CGF.createBasicBlock("dtor.call_delete");
     llvm::BasicBlock *continueBB = CGF.createBasicBlock("dtor.continue");
-    auto *CondTy = cast<llvm::IntegerType>(ShouldDeleteCondition->getType());
-    llvm::Value *CheckTheBit = CGF.Builder.CreateAnd(
-        ShouldDeleteCondition, llvm::ConstantInt::get(CondTy, 1));
-    llvm::Value *ShouldCallDelete = CGF.Builder.CreateIsNull(CheckTheBit);
+    llvm::Value *ShouldCallDelete
+      = CGF.Builder.CreateIsNull(ShouldDeleteCondition);
     CGF.Builder.CreateCondBr(ShouldCallDelete, continueBB, callDeleteBB);
 
     CGF.EmitBlock(callDeleteBB);