From 2228b4b46c3e45b5aab801a636041ed13ae47375 Mon Sep 17 00:00:00 2001 From: Harald van Dijk Date: Thu, 24 Jul 2025 18:43:17 +0100 Subject: clang: Handle deleting pointers to incomplete array types (#150359) CodeGenFunction::EmitCXXDeleteExpr contains logic to go from a pointer to an array to a pointer to the first element of the array using a getelementptr LLVM IR instruction. This was done for pointers that were not variable length arrays, as pointers to variable length arrays never existed in LLVM IR, but rather than checking for arrays that were not variable length arrays, it checked for arrays that had a constant bound. This caused incomplete arrays to be inadvertently omitted. This getelementptr was necessary back when LLVM IR used typed pointers, but they have been gone for a while, a gep with a constant zero offset does nothing now, so we can simplify the code by removing that. --- clang/lib/CodeGen/CGExprCXX.cpp | 27 +++------------------------ 1 file changed, 3 insertions(+), 24 deletions(-) (limited to 'clang/lib/CodeGen/CGExprCXX.cpp') diff --git a/clang/lib/CodeGen/CGExprCXX.cpp b/clang/lib/CodeGen/CGExprCXX.cpp index 359e30cb8f5c..b8238a4702c4 100644 --- a/clang/lib/CodeGen/CGExprCXX.cpp +++ b/clang/lib/CodeGen/CGExprCXX.cpp @@ -2146,30 +2146,9 @@ void CodeGenFunction::EmitCXXDeleteExpr(const CXXDeleteExpr *E) { return; } - // We might be deleting a pointer to array. If so, GEP down to the - // first non-array element. - // (this assumes that A(*)[3][7] is converted to [3 x [7 x %A]]*) - if (DeleteTy->isConstantArrayType()) { - llvm::Value *Zero = Builder.getInt32(0); - SmallVector GEP; - - GEP.push_back(Zero); // point at the outermost array - - // For each layer of array type we're pointing at: - while (const ConstantArrayType *Arr - = getContext().getAsConstantArrayType(DeleteTy)) { - // 1. Unpeel the array type. - DeleteTy = Arr->getElementType(); - - // 2. GEP to the first element of the array. - GEP.push_back(Zero); - } - - Ptr = Builder.CreateInBoundsGEP(Ptr, GEP, ConvertTypeForMem(DeleteTy), - Ptr.getAlignment(), "del.first"); - } - - assert(ConvertTypeForMem(DeleteTy) == Ptr.getElementType()); + // We might be deleting a pointer to array. + DeleteTy = getContext().getBaseElementType(DeleteTy); + Ptr = Ptr.withElementType(ConvertTypeForMem(DeleteTy)); if (E->isArrayForm()) { EmitArrayDelete(*this, E, Ptr, DeleteTy); -- cgit v1.2.3