[PATCH] D145852: [Clang][AST] Fix __has_unique_object_representations computation for unnamed bitfields.
Roy Jacobson via Phabricator via cfe-commits
cfe-commits at lists.llvm.org
Wed Mar 29 04:16:34 PDT 2023
royjacobson updated this revision to Diff 509298.
royjacobson added a comment.
Add some ((packed)) tests
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D145852/new/
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
@@ -2828,6 +2828,17 @@
static_assert(!has_unique_object_representations<WeirdAlignmentUnion>::value, "Alignment causes padding");
static_assert(!has_unique_object_representations<WeirdAlignment[42]>::value, "Also no arrays that have padding");
+struct __attribute__((packed)) PackedNoPadding1 {
+ short i;
+ int j;
+};
+struct __attribute__((packed)) PackedNoPadding2 {
+ int j;
+ short i;
+};
+static_assert(has_unique_object_representations<PackedNoPadding1>::value, "Packed structs have no padding");
+static_assert(has_unique_object_representations<PackedNoPadding2>::value, "Packed structs have no padding");
+
static_assert(!has_unique_object_representations<int(int)>::value, "Functions are not unique");
static_assert(!has_unique_object_representations<int(int) const>::value, "Functions are not unique");
static_assert(!has_unique_object_representations<int(int) volatile>::value, "Functions are not unique");
@@ -2878,9 +2889,35 @@
char d : 2;
};
+struct UnnamedBitfield {
+ int named : 8;
+ int : 24;
+};
+
+struct __attribute__((packed)) UnnamedBitfieldPacked {
+ int named : 8;
+ int : 24;
+};
+
+struct UnnamedEmptyBitfield {
+ int named;
+ int : 0;
+};
+
+struct UnnamedEmptyBitfieldSplit {
+ short named;
+ int : 0;
+ short also_named;
+};
+
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");
+static_assert(!has_unique_object_representations<UnnamedBitfieldPacked>::value, "Bitfield padding");
+static_assert(has_unique_object_representations<UnnamedEmptyBitfield>::value, "Bitfield padding");
+static_assert(sizeof(UnnamedEmptyBitfieldSplit) != (sizeof(short) * 2), "Wrong size");
+static_assert(!has_unique_object_representations<UnnamedEmptyBitfieldSplit>::value, "Bitfield padding");
struct BoolBitfield {
bool b : 8;
Index: clang/lib/AST/ASTContext.cpp
===================================================================
--- clang/lib/AST/ASTContext.cpp
+++ clang/lib/AST/ASTContext.cpp
@@ -2810,6 +2810,11 @@
int64_t FieldSizeInBits =
Context.toBits(Context.getTypeSizeInChars(Field->getType()));
if (Field->isBitField()) {
+ // If we have explicit padding bits, they don't contribute bits
+ // to the actual object representation, so return 0.
+ if (Field->isUnnamedBitfield())
+ return 0;
+
int64_t BitfieldSize = Field->getBitWidthValue(Context);
if (IsBitIntType) {
if ((unsigned)BitfieldSize >
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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