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[CIR] Backport a fix for array element destruction order. #1823

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Merged
merged 2 commits into from
Aug 15, 2025
Merged

[CIR] Backport a fix for array element destruction order. #1823

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d14e612
[CIR] Fix the order of array element destruction
andykaylor Aug 14, 2025
45041a2
This is the bulk of the change.
andykaylor Aug 14, 2025
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38 changes: 23 additions & 15 deletions clang/lib/CIR/Dialect/Transforms/LoweringPrepare.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1333,27 +1333,30 @@ void LoweringPreparePass::lowerDynamicCastOp(DynamicCastOp op) {

static void lowerArrayDtorCtorIntoLoop(CIRBaseBuilderTy &builder,
mlir::Operation *op, mlir::Type eltTy,
mlir::Value arrayAddr,
uint64_t arrayLen) {
mlir::Value arrayAddr, uint64_t arrayLen,
bool isCtor) {
// Generate loop to call into ctor/dtor for every element.
auto loc = op->getLoc();

// TODO: instead of fixed integer size, create alias for PtrDiffTy and unify
// with CIRGen stuff.
auto ptrDiffTy =
cir::IntType::get(builder.getContext(), 64, /*signed=*/false);
auto numArrayElementsConst = builder.create<cir::ConstantOp>(
loc, ptrDiffTy, cir::IntAttr::get(ptrDiffTy, arrayLen));
uint64_t endOffset = isCtor ? arrayLen : arrayLen - 1;
mlir::Value endOffsetVal = builder.create<cir::ConstantOp>(
loc, ptrDiffTy, cir::IntAttr::get(ptrDiffTy, endOffset));

auto begin = builder.create<cir::CastOp>(
loc, eltTy, cir::CastKind::array_to_ptrdecay, arrayAddr);
mlir::Value end = builder.create<cir::PtrStrideOp>(loc, eltTy, begin,
numArrayElementsConst);
mlir::Value end =
builder.create<cir::PtrStrideOp>(loc, eltTy, begin, endOffsetVal);
mlir::Value start = isCtor ? begin : end;
mlir::Value stop = isCtor ? end : begin;

auto tmpAddr = builder.createAlloca(
loc, /*addr type*/ builder.getPointerTo(eltTy),
/*var type*/ eltTy, "__array_idx", clang::CharUnits::One());
builder.createStore(loc, begin, tmpAddr);
builder.createStore(loc, start, tmpAddr);

auto loop = builder.createDoWhile(
loc,
Expand All @@ -1362,7 +1365,7 @@ static void lowerArrayDtorCtorIntoLoop(CIRBaseBuilderTy &builder,
auto currentElement = b.create<cir::LoadOp>(loc, eltTy, tmpAddr);
mlir::Type boolTy = cir::BoolType::get(b.getContext());
auto cmp = builder.create<cir::CmpOp>(loc, boolTy, cir::CmpOpKind::ne,
currentElement, end);
currentElement, stop);
builder.createCondition(cmp);
},
/*bodyBuilder=*/
Expand All @@ -1373,15 +1376,20 @@ static void lowerArrayDtorCtorIntoLoop(CIRBaseBuilderTy &builder,
op->walk([&](CallOp c) { ctorCall = c; });
assert(ctorCall && "expected ctor call");

auto one = builder.create<cir::ConstantOp>(
loc, ptrDiffTy, cir::IntAttr::get(ptrDiffTy, 1));
cir::ConstantOp stride;
if (isCtor)
stride = builder.create<cir::ConstantOp>(
loc, ptrDiffTy, cir::IntAttr::get(ptrDiffTy, 1));
else
stride = builder.create<cir::ConstantOp>(
loc, ptrDiffTy, cir::IntAttr::get(ptrDiffTy, -1));

ctorCall->moveAfter(one);
ctorCall->moveBefore(stride);
ctorCall->setOperand(0, currentElement);

// Advance pointer and store them to temporary variable
auto nextElement =
builder.create<cir::PtrStrideOp>(loc, eltTy, currentElement, one);
auto nextElement = builder.create<cir::PtrStrideOp>(
loc, eltTy, currentElement, stride);
builder.createStore(loc, nextElement, tmpAddr);
builder.createYield(loc);
});
Expand All @@ -1397,7 +1405,7 @@ void LoweringPreparePass::lowerArrayDtor(ArrayDtor op) {
auto eltTy = op->getRegion(0).getArgument(0).getType();
auto arrayLen =
mlir::cast<cir::ArrayType>(op.getAddr().getType().getPointee()).getSize();
lowerArrayDtorCtorIntoLoop(builder, op, eltTy, op.getAddr(), arrayLen);
lowerArrayDtorCtorIntoLoop(builder, op, eltTy, op.getAddr(), arrayLen, false);
}

static std::string getGlobalVarNameForConstString(cir::StoreOp op,
Expand Down Expand Up @@ -1460,7 +1468,7 @@ void LoweringPreparePass::lowerArrayCtor(ArrayCtor op) {
auto eltTy = op->getRegion(0).getArgument(0).getType();
auto arrayLen =
mlir::cast<cir::ArrayType>(op.getAddr().getType().getPointee()).getSize();
lowerArrayDtorCtorIntoLoop(builder, op, eltTy, op.getAddr(), arrayLen);
lowerArrayDtorCtorIntoLoop(builder, op, eltTy, op.getAddr(), arrayLen, true);
}

void LoweringPreparePass::lowerStdFindOp(StdFindOp op) {
Expand Down
34 changes: 24 additions & 10 deletions clang/test/CIR/CodeGen/array-init-destroy.cpp
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@@ -1,6 +1,9 @@
// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir -mmlir --mlir-print-ir-before=cir-lowering-prepare %s -o %t1.cir 2>&1 | FileCheck -check-prefix=BEFORE %s
// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir -mmlir --mlir-print-ir-after=cir-lowering-prepare %s -o %t2.cir 2>&1 | FileCheck -check-prefix=AFTER %s

// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir -mmlir --mlir-print-ir-before=cir-lowering-prepare %s -o %t.cir &> %t1.cir
// RUN: FileCheck --input-file=%t1.cir -check-prefix=BEFORE %s
// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir -mmlir --mlir-print-ir-after=cir-lowering-prepare %s -o %t.cir &> %t2.cir
// RUN: FileCheck --input-file=%t2.cir -check-prefix=AFTER %s
// Note: The run lines above send the final CIR to %t.cir, but that's ignored.
// The test checks the CIR before and after the cir-lowering-prepare pass.
void foo() noexcept;

class xpto {
Expand Down Expand Up @@ -43,8 +46,8 @@ void x() {
// AFTER: cir.store %[[ArrayBegin]], %[[TmpIdx]] : !cir.ptr<!rec_xpto>, !cir.ptr<!cir.ptr<!rec_xpto>>
// AFTER: cir.do {
// AFTER: %[[ArrayElt:.*]] = cir.load %[[TmpIdx]] : !cir.ptr<!cir.ptr<!rec_xpto>>, !cir.ptr<!rec_xpto>
// AFTER: %[[ConstOne:.*]] = cir.const #cir.int<1> : !u64i
// AFTER: cir.call @_ZN4xptoC1Ev(%[[ArrayElt]]) : (!cir.ptr<!rec_xpto>) -> ()
// AFTER: %[[ConstOne:.*]] = cir.const #cir.int<1> : !u64i
// AFTER: %[[NextElt:.*]] = cir.ptr_stride(%[[ArrayElt]] : !cir.ptr<!rec_xpto>, %[[ConstOne]] : !u64i), !cir.ptr<!rec_xpto>
// AFTER: cir.store %[[NextElt]], %[[TmpIdx]] : !cir.ptr<!rec_xpto>, !cir.ptr<!cir.ptr<!rec_xpto>>
// AFTER: cir.yield
Expand All @@ -53,10 +56,21 @@ void x() {
// AFTER: %[[ExitCond:.*]] = cir.cmp(ne, %[[ArrayElt]], %[[ArrayPastEnd]]) : !cir.ptr<!rec_xpto>, !cir.bool
// AFTER: cir.condition(%[[ExitCond]])
// AFTER: }

// AFTER: cir.do {
// AFTER: cir.call @_ZN4xptoD1Ev({{.*}}) : (!cir.ptr<!rec_xpto>) -> ()
// AFTER: } while {
// AFTER: }

// AFTER: %[[ConstOne:.*]] = cir.const #cir.int<1> : !u64i
// AFTER: %[[ArrayBegin:.*]] = cir.cast(array_to_ptrdecay, %[[ArrayAddr0]] : !cir.ptr<!cir.array<!rec_xpto x 2>>), !cir.ptr<!rec_xpto>
// AFTER: %[[ArrayEnd:.*]] = cir.ptr_stride(%[[ArrayBegin]] : !cir.ptr<!rec_xpto>, %[[ConstOne]] : !u64i), !cir.ptr<!rec_xpto>
// AFTER: %[[TmpIdx:.*]] = cir.alloca !cir.ptr<!rec_xpto>, !cir.ptr<!cir.ptr<!rec_xpto>>, ["__array_idx"] {alignment = 1 : i64}
// AFTER: cir.store %[[ArrayEnd]], %[[TmpIdx]] : !cir.ptr<!rec_xpto>, !cir.ptr<!cir.ptr<!rec_xpto>>
// AFTER cir.do {
// AFTER %[[ArrElt:.*]] = cir.load{{.*}} %[[TmpIdx]]
// AFTER cir.call @_ZN13array_elementD1Ev(%[[ArrElt]]) : (!cir.ptr<!rec_xpto>) -> ()
// AFTER %[[ConstNegOne:.*]] = cir.const #cir.int<-1> : !s64i
// AFTER %[[NextElt:.*]] = cir.ptr_stride(%[[ARR_CUR]] : !cir.ptr<!rec_xpto>, %[[ConstNegOne]] : !s64i), !cir.ptr<!rec_xpto>
// AFTER cir.store %[[NextElt]], %[[TmpIdx]] : !cir.ptr<!rec_xpto>, !cir.ptr<!cir.ptr<!rec_xpto>>
// AFTER cir.yield
// AFTER } while {
// AFTER %[[ArrElt:.*]] = cir.load %[[TmpIdx]] : !cir.ptr<!cir.ptr<!rec_xpto>>, !cir.ptr<!rec_xpto>
// AFTER: %[[ExitCond:.*]] = cir.cmp(ne, %[[ArrayElt]], %[[ArrayBegin]]) : !cir.ptr<!rec_xpto>, !cir.bool
// AFTER cir.condition(%[[ExitCond]])
// AFTER }
// AFTER: cir.return
2 changes: 1 addition & 1 deletion clang/test/CIR/CodeGen/array-new-init.cpp
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Expand Up @@ -48,8 +48,8 @@ void t_new_constant_size_constructor() {
// AFTER: cir.store{{.*}} %[[ELEM_PTR]], %[[CUR_ELEM_ALLOCA]] : !cir.ptr<!rec_E>, !cir.ptr<!cir.ptr<!rec_E>>
// AFTER: cir.do {
// AFTER: %[[CUR_ELEM_PTR:.*]] = cir.load %[[CUR_ELEM_ALLOCA]] : !cir.ptr<!cir.ptr<!rec_E>>, !cir.ptr<!rec_E>
// AFTER: %[[OFFSET:.*]] = cir.const #cir.int<1> : !u64i
// AFTER: cir.call @_ZN1EC1Ev(%[[CUR_ELEM_PTR]]) : (!cir.ptr<!rec_E>) -> ()
// AFTER: %[[OFFSET:.*]] = cir.const #cir.int<1> : !u64i
// AFTER: %[[NEXT_PTR:.*]] = cir.ptr_stride(%[[CUR_ELEM_PTR]] : !cir.ptr<!rec_E>, %[[OFFSET]] : !u64i), !cir.ptr<!rec_E>
// AFTER: cir.store{{.*}} %[[NEXT_PTR]], %[[CUR_ELEM_ALLOCA]] : !cir.ptr<!rec_E>, !cir.ptr<!cir.ptr<!rec_E>>
// AFTER: cir.yield
Expand Down
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