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ms_struct does not imply the MS base-layout ABI; separate these 

conditions in the IRGen struct layout code.

rdar://20636558

llvm-svn: 235949
This commit is contained in:
John McCall 2015-04-28 00:17:18 +00:00
parent 0bbe4f2c8e
commit f3e86a7a55
2 changed files with 56 additions and 6 deletions
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29
clang/lib/CodeGen/CGRecordLayoutBuilder.cpp
View File

@ -99,10 +99,25 @@ struct CGRecordLowering {
MemberInfo StorageInfo(CharUnits Offset, llvm::Type *Data) {
return MemberInfo(Offset, MemberInfo::Field, Data);
}
bool useMSABI() {
/// The Microsoft bitfield layout rule allocates discrete storage
/// units of the field's formal type and only combines adjacent
/// fields of the same formal type. We want to emit a layout with
/// these discrete storage units instead of combining them into a
/// continuous run.
bool isDiscreteBitFieldABI() {
return Context.getTargetInfo().getCXXABI().isMicrosoft() ||
D->isMsStruct(Context);
}
/// The Itanium base layout rule allows virtual bases to overlap
/// other bases, which complicates layout in specific ways.
///
/// Note specifically that the ms_struct attribute doesn't change this.
bool isOverlappingVBaseABI() {
return !Context.getTargetInfo().getCXXABI().isMicrosoft();
}
/// \brief Wraps llvm::Type::getIntNTy with some implicit arguments.
llvm::Type *getIntNType(uint64_t NumBits) {
return llvm::Type::getIntNTy(Types.getLLVMContext(),
@ -119,8 +134,9 @@ struct CGRecordLowering {
/// for itanium bitfields that are smaller than their declared type.
llvm::Type *getStorageType(const FieldDecl *FD) {
llvm::Type *Type = Types.ConvertTypeForMem(FD->getType());
return useMSABI() || !FD->isBitField() ? Type :
getIntNType(std::min(FD->getBitWidthValue(Context),
if (!FD->isBitField()) return Type;
if (isDiscreteBitFieldABI()) return Type;
return getIntNType(std::min(FD->getBitWidthValue(Context),
(unsigned)Context.toBits(getSize(Type))));
}
/// \brief Gets the llvm Basesubobject type from a CXXRecordDecl.
@ -365,7 +381,7 @@ CGRecordLowering::accumulateBitFields(RecordDecl::field_iterator Field,
// used to determine if the ASTRecordLayout is treating these two bitfields as
// contiguous. StartBitOffset is offset of the beginning of the Run.
uint64_t StartBitOffset, Tail = 0;
if (useMSABI()) {
if (isDiscreteBitFieldABI()) {
for (; Field != FieldEnd; ++Field) {
uint64_t BitOffset = getFieldBitOffset(*Field);
// Zero-width bitfields end runs.
@ -465,7 +481,7 @@ void CGRecordLowering::accumulateVBases() {
// smaller than the nvsize. Here we check to see if such a base is placed
// before the nvsize and set the scissor offset to that, instead of the
// nvsize.
if (!useMSABI())
if (isOverlappingVBaseABI())
for (const auto &Base : RD->vbases()) {
const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
if (BaseDecl->isEmpty())
@ -486,7 +502,8 @@ void CGRecordLowering::accumulateVBases() {
CharUnits Offset = Layout.getVBaseClassOffset(BaseDecl);
// If the vbase is a primary virtual base of some base, then it doesn't
// get its own storage location but instead lives inside of that base.
if (!useMSABI() && Context.isNearlyEmpty(BaseDecl) &&
if (isOverlappingVBaseABI() &&
Context.isNearlyEmpty(BaseDecl) &&
!hasOwnStorage(RD, BaseDecl)) {
Members.push_back(MemberInfo(Offset, MemberInfo::VBase, nullptr,
BaseDecl));

33
clang/test/CodeGenCXX/ms_struct.cpp Normal file
View File

@ -0,0 +1,33 @@
// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -emit-llvm %s -o - | FileCheck %s
// rdar://20636558
#pragma GCC diagnostic ignored "-Wincompatible-ms-struct"
#define ATTR __attribute__((__ms_struct__))
struct ATTR VBase {
virtual void foo() = 0;
};
struct ATTR Base : virtual VBase {
virtual void bar() = 0;
};
struct ATTR Derived : Base {
Derived();
void foo();
void bar();
int value;
};
// CHECK: [[DERIVED:%.*]] = type <{ [[BASE:%.*]], i32, [4 x i8] }>
// CHECK: [[BASE]] = type { [[VBASE:%.*]] }
// CHECK: [[VBASE]] = type { i32 (...)** }
// CHECK: define void @_ZN7DerivedC2Ev
// CHECK: [[SELF:%.*]] = load [[DERIVED]]*
// CHECK: [[T0:%.*]] = bitcast [[DERIVED]]* [[SELF]] to [[BASE]]*
// CHECK: call void @_ZN4BaseC2Ev([[BASE]]* [[T0]], i8**
// CHECK: [[T0:%.*]] = getelementptr inbounds {{.*}} [[SELF]], i32 0, i32 1
// CHECK: store i32 20, i32* [[T0]],
Derived::Derived() : value(20) {}