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Merged
merged 4 commits into from
Jul 24, 2025
Merged

clang: Handle deleting pointers to incomplete array types #150359

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0f98715
clang: Handle deleting pointers to incomplete array types
hvdijk Jul 24, 2025
345f149
Include PR number.
hvdijk Jul 24, 2025
a2abd1e
Use getContext().getBaseElementType(DeleteTy).
hvdijk Jul 24, 2025
25c535a
Merge remote-tracking branch 'origin/main' into fix-delete-ptr-to-inc…
hvdijk Jul 24, 2025
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1 change: 1 addition & 0 deletions clang/docs/ReleaseNotes.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -134,6 +134,7 @@ Bug Fixes to C++ Support
^^^^^^^^^^^^^^^^^^^^^^^^
- Diagnose binding a reference to ``*nullptr`` during constant evaluation. (#GH48665)
- Suppress ``-Wdeprecated-declarations`` in implicitly generated functions. (#GH147293)
- Fix a crash when deleting a pointer to an incomplete array (#GH150359).

Bug Fixes to AST Handling
^^^^^^^^^^^^^^^^^^^^^^^^^
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27 changes: 3 additions & 24 deletions clang/lib/CodeGen/CGExprCXX.cpp
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Expand Up @@ -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<llvm::Value*,8> 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);
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32 changes: 25 additions & 7 deletions clang/test/CodeGenCXX/delete.cpp
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Expand Up @@ -76,27 +76,45 @@ namespace test1 {
~A();
};

// CHECK-LABEL: define{{.*}} void @_ZN5test14testEPA10_A20_NS_1AE(
void test(A (*arr)[10][20]) {
// CHECK-LABEL: define{{.*}} void @_ZN5test11fEPA10_A20_NS_1AE(
void f(A (*arr)[10][20]) {
delete [] arr;
// CHECK: icmp eq ptr [[PTR:%.*]], null
// CHECK-NEXT: br i1

// CHECK: [[BEGIN:%.*]] = getelementptr inbounds [10 x [20 x [[A:%.*]]]], ptr [[PTR]], i32 0, i32 0, i32 0
// CHECK-NEXT: [[ALLOC:%.*]] = getelementptr inbounds i8, ptr [[BEGIN]], i64 -8
// CHECK: [[ALLOC:%.*]] = getelementptr inbounds i8, ptr [[PTR]], i64 -8
// CHECK-NEXT: [[COUNT:%.*]] = load i64, ptr [[ALLOC]]
// CHECK: [[END:%.*]] = getelementptr inbounds [[A]], ptr [[BEGIN]], i64 [[COUNT]]
// CHECK-NEXT: [[ISEMPTY:%.*]] = icmp eq ptr [[BEGIN]], [[END]]
// CHECK: [[END:%.*]] = getelementptr inbounds [[A:%.*]], ptr [[PTR]], i64 [[COUNT]]
// CHECK-NEXT: [[ISEMPTY:%.*]] = icmp eq ptr [[PTR]], [[END]]
// CHECK-NEXT: br i1 [[ISEMPTY]],
// CHECK: [[PAST:%.*]] = phi ptr [ [[END]], {{%.*}} ], [ [[CUR:%.*]], {{%.*}} ]
// CHECK-NEXT: [[CUR:%.*]] = getelementptr inbounds [[A]], ptr [[PAST]], i64 -1
// CHECK-NEXT: call void @_ZN5test11AD1Ev(ptr {{[^,]*}} [[CUR]])
// CHECK-NEXT: [[ISDONE:%.*]] = icmp eq ptr [[CUR]], [[BEGIN]]
// CHECK-NEXT: [[ISDONE:%.*]] = icmp eq ptr [[CUR]], [[PTR]]
// CHECK-NEXT: br i1 [[ISDONE]]
// CHECK: [[MUL:%.*]] = mul i64 4, [[COUNT]]
// CHECK-NEXT: [[SIZE:%.*]] = add i64 [[MUL]], 8
// CHECK-NEXT: call void @_ZdaPvm(ptr noundef [[ALLOC]], i64 noundef [[SIZE]])
}

// CHECK-LABEL: define{{.*}} void @_ZN5test11gEPA_NS_1AE(
void g(A (*arr)[]) {
delete [] arr;
// CHECK: icmp eq ptr [[PTR:%.*]], null
// CHECK-NEXT: br i1

// CHECK: [[ALLOC:%.*]] = getelementptr inbounds i8, ptr [[PTR]], i64 -8
// CHECK-NEXT: [[COUNT:%.*]] = load i64, ptr [[ALLOC]]
// CHECK: [[END:%.*]] = getelementptr inbounds [[A:%.*]], ptr [[PTR]], i64 [[COUNT]]
// CHECK-NEXT: [[ISEMPTY:%.*]] = icmp eq ptr [[PTR]], [[END]]
// CHECK-NEXT: br i1 [[ISEMPTY]],
// CHECK: [[PAST:%.*]] = phi ptr [ [[END]], {{%.*}} ], [ [[CUR:%.*]], {{%.*}} ]
// CHECK-NEXT: [[CUR:%.*]] = getelementptr inbounds [[A]], ptr [[PAST]], i64 -1
// CHECK-NEXT: call void @_ZN5test11AD1Ev(ptr {{[^,]*}} [[CUR]])
// CHECK-NEXT: [[ISDONE:%.*]] = icmp eq ptr [[CUR]], [[PTR]]
// CHECK-NEXT: br i1 [[ISDONE]]
// CHECK: call void @_ZdaPv(ptr noundef [[ALLOC]])
}
}

namespace test2 {
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