When laying out bitfields, make sure that the data size is always aligned to a byte. This fixes PR5580.
llvm-svn: 89611
diff --git a/clang/lib/AST/RecordLayoutBuilder.cpp b/clang/lib/AST/RecordLayoutBuilder.cpp
index 8e4e160..5bc27b9 100644
--- a/clang/lib/AST/RecordLayoutBuilder.cpp
+++ b/clang/lib/AST/RecordLayoutBuilder.cpp
@@ -22,9 +22,9 @@
using namespace clang;
ASTRecordLayoutBuilder::ASTRecordLayoutBuilder(ASTContext &Ctx)
- : Ctx(Ctx), Size(0), Alignment(8), Packed(false), MaxFieldAlignment(0),
- DataSize(0), IsUnion(false), NonVirtualSize(0), NonVirtualAlignment(8),
- PrimaryBase(0), PrimaryBaseWasVirtual(false) {}
+ : Ctx(Ctx), Size(0), Alignment(8), Packed(false), UnfilledBitsInLastByte(0),
+ MaxFieldAlignment(0), DataSize(0), IsUnion(false), NonVirtualSize(0),
+ NonVirtualAlignment(8), PrimaryBase(0), PrimaryBaseWasVirtual(false) {}
/// LayoutVtable - Lay out the vtable and set PrimaryBase.
void ASTRecordLayoutBuilder::LayoutVtable(const CXXRecordDecl *RD) {
@@ -521,7 +521,7 @@
void ASTRecordLayoutBuilder::LayoutBitField(const FieldDecl *D) {
bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
- uint64_t FieldOffset = IsUnion ? 0 : DataSize;
+ uint64_t FieldOffset = IsUnion ? 0 : (DataSize - UnfilledBitsInLastByte);
uint64_t FieldSize = D->getBitWidth()->EvaluateAsInt(Ctx).getZExtValue();
std::pair<uint64_t, unsigned> FieldInfo = Ctx.getTypeInfo(D->getType());
@@ -549,14 +549,19 @@
// Place this field at the current location.
FieldOffsets.push_back(FieldOffset);
- // Reserve space for this field.
- if (IsUnion)
- Size = std::max(Size, FieldSize);
- else
- Size = FieldOffset + FieldSize;
+ // Update DataSize to include the last byte containing (part of) the bitfield.
+ if (IsUnion) {
+ // FIXME: I think FieldSize should be TypeSize here.
+ DataSize = std::max(DataSize, FieldSize);
+ } else {
+ uint64_t NewSizeInBits = FieldOffset + FieldSize;
+
+ DataSize = llvm::RoundUpToAlignment(NewSizeInBits, 8);
+ UnfilledBitsInLastByte = DataSize - NewSizeInBits;
+ }
- // Update the data size.
- DataSize = Size;
+ // Update the size.
+ Size = std::max(Size, DataSize);
// Remember max struct/class alignment.
UpdateAlignment(FieldAlign);
@@ -568,6 +573,9 @@
return;
}
+ // Reset the unfilled bits.
+ UnfilledBitsInLastByte = 0;
+
bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
uint64_t FieldOffset = IsUnion ? 0 : DataSize;
uint64_t FieldSize;