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As pointed out in https://github.com/llvm/llvm-project/issues/61336, objects
with
unnamed bitfields aren't be uniquely representable.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D145852
Files:
clang/docs/ReleaseNotes.rst
clang/lib/AST/ASTContext.cpp
clang/test/SemaCXX/type-traits.cpp
Index: clang/test/SemaCXX/type-traits.cpp
===================================================================
--- clang/test/SemaCXX/type-traits.cpp
+++ clang/test/SemaCXX/type-traits.cpp
@@ -2878,9 +2878,15 @@
char d : 2;
};
+struct UnnamedBitfield {
+ int named : 8;
+ int : 24;
+};
+
static_assert(!has_unique_object_representations<PaddedBitfield>::value,
"Bitfield padding");
static_assert(has_unique_object_representations<UnPaddedBitfield>::value,
"Bitfield padding");
static_assert(!has_unique_object_representations<AlignedPaddedBitfield>::value,
"Bitfield padding");
+static_assert(!has_unique_object_representations<UnnamedBitfield>::value,
"Bitfield padding");
struct BoolBitfield {
bool b : 8;
Index: clang/lib/AST/ASTContext.cpp
===================================================================
--- clang/lib/AST/ASTContext.cpp
+++ clang/lib/AST/ASTContext.cpp
@@ -2831,13 +2831,17 @@
return structHasUniqueObjectRepresentations(Context, RD);
}
-template <typename RangeT>
+template <bool CheckUnnamedBitFields, typename RangeT>
static std::optional<int64_t> structSubobjectsHaveUniqueObjectRepresentations(
const RangeT &Subobjects, int64_t CurOffsetInBits,
const ASTContext &Context, const clang::ASTRecordLayout &Layout) {
for (const auto *Subobject : Subobjects) {
std::optional<int64_t> SizeInBits =
getSubobjectSizeInBits(Subobject, Context);
+ if constexpr (CheckUnnamedBitFields) {
+ if (Subobject->isUnnamedBitfield())
+ return std::nullopt;
+ }
if (!SizeInBits)
return std::nullopt;
if (*SizeInBits != 0) {
@@ -2873,15 +2877,15 @@
});
std::optional<int64_t> OffsetAfterBases =
- structSubobjectsHaveUniqueObjectRepresentations(Bases, CurOffsetInBits,
- Context, Layout);
+ structSubobjectsHaveUniqueObjectRepresentations<false>(
+ Bases, CurOffsetInBits, Context, Layout);
if (!OffsetAfterBases)
return std::nullopt;
CurOffsetInBits = *OffsetAfterBases;
}
std::optional<int64_t> OffsetAfterFields =
- structSubobjectsHaveUniqueObjectRepresentations(
+ structSubobjectsHaveUniqueObjectRepresentations<true>(
RD->fields(), CurOffsetInBits, Context, Layout);
if (!OffsetAfterFields)
return std::nullopt;
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -202,6 +202,9 @@
- Fix crash when evaluating consteval constructor of derived class whose base
has more than one field.
(`#60166 <https://github.com/llvm/llvm-project/issues/60166>`_)
+- Fix bug in the computation of the ``__has_unique_object_representations``
+ builtin for types with unnamed bitfields.
+ (`#61336 <https://github.com/llvm/llvm-project/issues/61336>`_)
Bug Fixes to AST Handling
^^^^^^^^^^^^^^^^^^^^^^^^^
Index: clang/test/SemaCXX/type-traits.cpp
===================================================================
--- clang/test/SemaCXX/type-traits.cpp
+++ clang/test/SemaCXX/type-traits.cpp
@@ -2878,9 +2878,15 @@
char d : 2;
};
+struct UnnamedBitfield {
+ int named : 8;
+ int : 24;
+};
+
static_assert(!has_unique_object_representations<PaddedBitfield>::value, "Bitfield padding");
static_assert(has_unique_object_representations<UnPaddedBitfield>::value, "Bitfield padding");
static_assert(!has_unique_object_representations<AlignedPaddedBitfield>::value, "Bitfield padding");
+static_assert(!has_unique_object_representations<UnnamedBitfield>::value, "Bitfield padding");
struct BoolBitfield {
bool b : 8;
Index: clang/lib/AST/ASTContext.cpp
===================================================================
--- clang/lib/AST/ASTContext.cpp
+++ clang/lib/AST/ASTContext.cpp
@@ -2831,13 +2831,17 @@
return structHasUniqueObjectRepresentations(Context, RD);
}
-template <typename RangeT>
+template <bool CheckUnnamedBitFields, typename RangeT>
static std::optional<int64_t> structSubobjectsHaveUniqueObjectRepresentations(
const RangeT &Subobjects, int64_t CurOffsetInBits,
const ASTContext &Context, const clang::ASTRecordLayout &Layout) {
for (const auto *Subobject : Subobjects) {
std::optional<int64_t> SizeInBits =
getSubobjectSizeInBits(Subobject, Context);
+ if constexpr (CheckUnnamedBitFields) {
+ if (Subobject->isUnnamedBitfield())
+ return std::nullopt;
+ }
if (!SizeInBits)
return std::nullopt;
if (*SizeInBits != 0) {
@@ -2873,15 +2877,15 @@
});
std::optional<int64_t> OffsetAfterBases =
- structSubobjectsHaveUniqueObjectRepresentations(Bases, CurOffsetInBits,
- Context, Layout);
+ structSubobjectsHaveUniqueObjectRepresentations<false>(
+ Bases, CurOffsetInBits, Context, Layout);
if (!OffsetAfterBases)
return std::nullopt;
CurOffsetInBits = *OffsetAfterBases;
}
std::optional<int64_t> OffsetAfterFields =
- structSubobjectsHaveUniqueObjectRepresentations(
+ structSubobjectsHaveUniqueObjectRepresentations<true>(
RD->fields(), CurOffsetInBits, Context, Layout);
if (!OffsetAfterFields)
return std::nullopt;
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -202,6 +202,9 @@
- Fix crash when evaluating consteval constructor of derived class whose base
has more than one field.
(`#60166 <https://github.com/llvm/llvm-project/issues/60166>`_)
+- Fix bug in the computation of the ``__has_unique_object_representations``
+ builtin for types with unnamed bitfields.
+ (`#61336 <https://github.com/llvm/llvm-project/issues/61336>`_)
Bug Fixes to AST Handling
^^^^^^^^^^^^^^^^^^^^^^^^^
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