diff options
| -rw-r--r-- | include/clang/Basic/TargetInfo.h | 12 | ||||
| -rw-r--r-- | lib/AST/RecordLayoutBuilder.cpp | 7 | ||||
| -rw-r--r-- | lib/Basic/TargetInfo.cpp | 6 |
3 files changed, 18 insertions, 7 deletions
diff --git a/include/clang/Basic/TargetInfo.h b/include/clang/Basic/TargetInfo.h index bc2cf198c3..55669faa45 100644 --- a/include/clang/Basic/TargetInfo.h +++ b/include/clang/Basic/TargetInfo.h @@ -85,6 +85,14 @@ public: protected: IntType SizeType, IntMaxType, UIntMaxType, PtrDiffType, IntPtrType, WCharType, WIntType, Char16Type, Char32Type, Int64Type, SigAtomicType; + + /// Control whether the alignment of bit-field types is respected when laying + /// out structures. If true, then the alignment of the bit-field type will be + /// used to (a) impact the alignment of the containing structure, and (b) + /// ensure that the individual bit-field will not straddle an alignment + /// boundary. + unsigned UseBitfieldTypeAlignment : 1; + public: IntType getSizeType() const { return SizeType; } IntType getIntMaxType() const { return IntMaxType; } @@ -197,6 +205,10 @@ public: return UserLabelPrefix; } + bool useBitfieldTypeAlignment() const { + return UseBitfieldTypeAlignment; + } + /// getTypeName - Return the user string for the specified integer type enum. /// For example, SignedShort -> "short". static const char *getTypeName(IntType T); diff --git a/lib/AST/RecordLayoutBuilder.cpp b/lib/AST/RecordLayoutBuilder.cpp index bb73e7ea11..d312ee13fe 100644 --- a/lib/AST/RecordLayoutBuilder.cpp +++ b/lib/AST/RecordLayoutBuilder.cpp @@ -585,7 +585,7 @@ void ASTRecordLayoutBuilder::LayoutBitField(const FieldDecl *D) { uint64_t TypeSize = FieldInfo.first; unsigned FieldAlign = FieldInfo.second; - if (FieldPacked) + if (FieldPacked || !Ctx.Target.useBitfieldTypeAlignment()) FieldAlign = 1; if (const AlignedAttr *AA = D->getAttr<AlignedAttr>()) FieldAlign = std::max(FieldAlign, AA->getMaxAlignment()); @@ -594,12 +594,11 @@ void ASTRecordLayoutBuilder::LayoutBitField(const FieldDecl *D) { if (MaxFieldAlignment) FieldAlign = std::min(FieldAlign, MaxFieldAlignment); - // Check if we need to add padding to give the field the correct - // alignment. + // Check if we need to add padding to give the field the correct alignment. if (FieldSize == 0 || (FieldOffset & (FieldAlign-1)) + FieldSize > TypeSize) FieldOffset = (FieldOffset + (FieldAlign-1)) & ~(FieldAlign-1); - // Padding members don't affect overall alignment + // Padding members don't affect overall alignment. if (!D->getIdentifier()) FieldAlign = 1; diff --git a/lib/Basic/TargetInfo.cpp b/lib/Basic/TargetInfo.cpp index 136089fe90..8b4fdee47c 100644 --- a/lib/Basic/TargetInfo.cpp +++ b/lib/Basic/TargetInfo.cpp @@ -20,9 +20,8 @@ using namespace clang; // TargetInfo Constructor. TargetInfo::TargetInfo(const std::string &T) : Triple(T) { - // Set defaults. Defaults are set for a 32-bit RISC platform, - // like PPC or SPARC. - // These should be overridden by concrete targets as needed. + // Set defaults. Defaults are set for a 32-bit RISC platform, like PPC or + // SPARC. These should be overridden by concrete targets as needed. TLSSupported = true; PointerWidth = PointerAlign = 32; IntWidth = IntAlign = 32; @@ -45,6 +44,7 @@ TargetInfo::TargetInfo(const std::string &T) : Triple(T) { Char32Type = UnsignedInt; Int64Type = SignedLongLong; SigAtomicType = SignedInt; + UseBitfieldTypeAlignment = true; FloatFormat = &llvm::APFloat::IEEEsingle; DoubleFormat = &llvm::APFloat::IEEEdouble; LongDoubleFormat = &llvm::APFloat::IEEEdouble; |