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[clang][NFC] Remove class layout scissor #89055

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Merged
merged 3 commits into from
May 12, 2024
Merged

[clang][NFC] Remove class layout scissor #89055

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9ab483f
[clang] Remove class layout scissor
urnathan Apr 1, 2024
050df41
Fix param spelling
urnathan Apr 17, 2024
4b93593
lose attribute
urnathan May 6, 2024
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21 changes: 10 additions & 11 deletions clang/lib/CodeGen/CGRecordLayoutBuilder.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -75,7 +75,7 @@ struct CGRecordLowering {
// sentinel member type that ensures correct rounding.
struct MemberInfo {
CharUnits Offset;
enum InfoKind { VFPtr, VBPtr, Field, Base, VBase, Scissor } Kind;
enum InfoKind { VFPtr, VBPtr, Field, Base, VBase } Kind;
llvm::Type *Data;
union {
const FieldDecl *FD;
Expand Down Expand Up @@ -197,7 +197,7 @@ struct CGRecordLowering {
const CXXRecordDecl *Query) const;
void calculateZeroInit();
CharUnits calculateTailClippingOffset(bool isNonVirtualBaseType) const;
void checkBitfieldClipping() const;
void checkBitfieldClipping(bool isNonVirtualBaseType) const;
/// Determines if we need a packed llvm struct.
void determinePacked(bool NVBaseType);
/// Inserts padding everywhere it's needed.
Expand Down Expand Up @@ -299,8 +299,8 @@ void CGRecordLowering::lower(bool NVBaseType) {
accumulateVBases();
}
llvm::stable_sort(Members);
checkBitfieldClipping(NVBaseType);
Members.push_back(StorageInfo(Size, getIntNType(8)));
checkBitfieldClipping();
determinePacked(NVBaseType);
insertPadding();
Members.pop_back();
Expand Down Expand Up @@ -894,8 +894,6 @@ CGRecordLowering::calculateTailClippingOffset(bool isNonVirtualBaseType) const {
}

void CGRecordLowering::accumulateVBases() {
Members.push_back(MemberInfo(calculateTailClippingOffset(false),
MemberInfo::Scissor, nullptr, RD));
for (const auto &Base : RD->vbases()) {
const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
if (BaseDecl->isEmpty())
Expand Down Expand Up @@ -950,18 +948,19 @@ void CGRecordLowering::calculateZeroInit() {
}

// Verify accumulateBitfields computed the correct storage representations.
void CGRecordLowering::checkBitfieldClipping() const {
void CGRecordLowering::checkBitfieldClipping(bool IsNonVirtualBaseType) const {
#ifndef NDEBUG
auto ScissorOffset = calculateTailClippingOffset(IsNonVirtualBaseType);
auto Tail = CharUnits::Zero();
for (const auto &M : Members) {
// Only members with data and the scissor can cut into tail padding.
if (!M.Data && M.Kind != MemberInfo::Scissor)
// Only members with data could possibly overlap.
if (!M.Data)
continue;

assert(M.Offset >= Tail && "Bitfield access unit is not clipped");
Tail = M.Offset;
if (M.Data)
Tail += getSize(M.Data);
Tail = M.Offset + getSize(M.Data);
assert((Tail <= ScissorOffset || M.Offset >= ScissorOffset) &&
"Bitfield straddles scissor offset");
}
#endif
}
Expand Down