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[MS-ABI] adds padding before all vbases after a bitfield 

MS-ABI adds padding before *every* vbase if the last field in a record 
is a bit-field. This changes clangs behavior to match. I also fix some 
windows-style line endings in the test file.

Differential Revision: http://llvm-reviews.chandlerc.com/D2277

llvm-svn: 196605
This commit is contained in:
Warren Hunt 2013-12-06 20:16:49 +00:00
parent 1a68f2383f
commit 71140d68f8
2 changed files with 101 additions and 70 deletions
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15
clang/lib/AST/RecordLayoutBuilder.cpp
View File

@ -2014,9 +2014,9 @@ static bool isMsLayout(const RecordDecl* D) {
// one.
// * The last zero size virtual base may be placed at the end of the struct.
// and can potentially alias a zero sized type in the next struct.
// * If the last field is a non-zero length bitfield and we have any virtual
// bases then some extra padding is added before the virtual bases for no
// obvious reason.
// * If the last field is a non-zero length bitfield, all virtual bases will
// have extra padding added before them for no obvious reason. The padding
// has the same number of bits as the type of the bitfield.
// * When laying out empty non-virtual bases, an extra byte of padding is added
// if the non-virtual base before the empty non-virtual base has a vbptr.
// * The ABI attempts to avoid aliasing of zero sized bases by adding padding
@ -2558,17 +2558,16 @@ void MicrosoftRecordLayoutBuilder::layoutVirtualBases(const CXXRecordDecl *RD) {
llvm::SmallPtrSet<const CXXRecordDecl *, 2> HasVtordisp =
computeVtorDispSet(RD);
// If the last field we laid out was a non-zero length bitfield then add some
// extra padding for no obvious reason.
if (LastFieldIsNonZeroWidthBitfield)
Size += CurrentBitfieldSize;
// Iterate through the virtual bases and lay them out.
for (CXXRecordDecl::base_class_const_iterator i = RD->vbases_begin(),
e = RD->vbases_end();
i != e; ++i) {
const CXXRecordDecl *BaseDecl =
cast<CXXRecordDecl>(i->getType()->castAs<RecordType>()->getDecl());
// If the last field we laid out was a non-zero length bitfield then add
// some extra padding for no obvious reason.
if (LastFieldIsNonZeroWidthBitfield)
Size += CurrentBitfieldSize;
layoutVirtualBase(BaseDecl, HasVtordisp.count(BaseDecl));
}
}

156
clang/test/Layout/ms-x86-bitfields-vbases.cpp
View File

@ -3,82 +3,114 @@
// RUN: %clang_cc1 -fno-rtti -emit-llvm-only -triple x86_64-pc-win32 -fdump-record-layouts -fsyntax-only -cxx-abi microsoft %s 2>/dev/null \
// RUN: | FileCheck %s -check-prefix CHECK-X64
struct B0 { };
struct A : virtual B0 { char a : 1; };
struct B0 { int a; };
struct B1 { int a; };
// CHECK: *** Dumping AST Record Layout
// CHECK: 0 | struct A
// CHECK: 0 | (A vbtable pointer)
// CHECK: 4 | char a
// CHECK: 9 | struct B0 (virtual base) (empty)
// CHECK: | [sizeof=9, align=4
// CHECK: | nvsize=8, nvalign=4]
// CHECK-X64: *** Dumping AST Record Layout
// CHECK-X64: 0 | struct A
// CHECK-X64: 0 | (A vbtable pointer)
// CHECK-X64: 8 | char a
// CHECK-X64: 17 | struct B0 (virtual base) (empty)
// CHECK-X64: | [sizeof=24, align=8
// CHECK-X64: | nvsize=16, nvalign=8]
struct B : virtual B0 { short a : 1; };
struct A : virtual B0 { char a : 1; };
// CHECK: *** Dumping AST Record Layout
// CHECK: 0 | struct B
// CHECK: 0 | (B vbtable pointer)
// CHECK: 4 | short a
// CHECK: 10 | struct B0 (virtual base) (empty)
// CHECK: | [sizeof=10, align=4
// CHECK: | nvsize=8, nvalign=4]
// CHECK: 0 | struct A
// CHECK: 0 | (A vbtable pointer)
// CHECK: 4 | char a
// CHECK: 12 | struct B0 (virtual base)
// CHECK: 12 | int a
// CHECK: | [sizeof=16, align=4
// CHECK: | nvsize=8, nvalign=4]
// CHECK-X64: *** Dumping AST Record Layout
// CHECK-X64: 0 | struct B
// CHECK-X64: 0 | (B vbtable pointer)
// CHECK-X64: 8 | short a
// CHECK-X64: 18 | struct B0 (virtual base) (empty)
// CHECK-X64: | [sizeof=24, align=8
// CHECK-X64: | nvsize=16, nvalign=8]
// CHECK-X64: 0 | struct A
// CHECK-X64: 0 | (A vbtable pointer)
// CHECK-X64: 8 | char a
// CHECK-X64: 20 | struct B0 (virtual base)
// CHECK-X64: 20 | int a
// CHECK-X64: | [sizeof=24, align=8
// CHECK-X64: | nvsize=16, nvalign=8]
struct C : virtual B0 { char a : 1; char : 0; };
struct B : virtual B0 { short a : 1; };
// CHECK: *** Dumping AST Record Layout
// CHECK: 0 | struct C
// CHECK: 0 | (C vbtable pointer)
// CHECK: 4 | char a
// CHECK: 5 | char
// CHECK: 8 | struct B0 (virtual base) (empty)
// CHECK: | [sizeof=8, align=4
// CHECK: | nvsize=8, nvalign=4]
// CHECK: 0 | struct B
// CHECK: 0 | (B vbtable pointer)
// CHECK: 4 | short a
// CHECK: 12 | struct B0 (virtual base)
// CHECK: 12 | int a
// CHECK: | [sizeof=16, align=4
// CHECK: | nvsize=8, nvalign=4]
// CHECK-X64: *** Dumping AST Record Layout
// CHECK-X64: 0 | struct C
// CHECK-X64: 0 | (C vbtable pointer)
// CHECK-X64: 8 | char a
// CHECK-X64: 9 | char
// CHECK-X64: 16 | struct B0 (virtual base) (empty)
// CHECK-X64: | [sizeof=16, align=8
// CHECK-X64: | nvsize=16, nvalign=8]
// CHECK-X64: 0 | struct B
// CHECK-X64: 0 | (B vbtable pointer)
// CHECK-X64: 8 | short a
// CHECK-X64: 20 | struct B0 (virtual base)
// CHECK-X64: 20 | int a
// CHECK-X64: | [sizeof=24, align=8
// CHECK-X64: | nvsize=16, nvalign=8]
struct D : virtual B0 { char a : 1; char b; };
struct C : virtual B0 { char a : 1; char : 0; };
// CHECK: *** Dumping AST Record Layout
// CHECK: 0 | struct D
// CHECK: 0 | (D vbtable pointer)
// CHECK: 4 | char a
// CHECK: 5 | char b
// CHECK: 8 | struct B0 (virtual base) (empty)
// CHECK: | [sizeof=8, align=4
// CHECK: | nvsize=8, nvalign=4]
// CHECK: 0 | struct C
// CHECK: 0 | (C vbtable pointer)
// CHECK: 4 | char a
// CHECK: 5 | char
// CHECK: 8 | struct B0 (virtual base)
// CHECK: 8 | int a
// CHECK: | [sizeof=12, align=4
// CHECK: | nvsize=8, nvalign=4]
// CHECK-X64: *** Dumping AST Record Layout
// CHECK-X64: 0 | struct D
// CHECK-X64: 0 | (D vbtable pointer)
// CHECK-X64: 8 | char a
// CHECK-X64: 9 | char b
// CHECK-X64: 16 | struct B0 (virtual base) (empty)
// CHECK-X64: | [sizeof=16, align=8
// CHECK-X64: | nvsize=16, nvalign=8]
// CHECK-X64: 0 | struct C
// CHECK-X64: 0 | (C vbtable pointer)
// CHECK-X64: 8 | char a
// CHECK-X64: 9 | char
// CHECK-X64: 16 | struct B0 (virtual base)
// CHECK-X64: 16 | int a
// CHECK-X64: | [sizeof=24, align=8
// CHECK-X64: | nvsize=16, nvalign=8]
struct D : virtual B0 { char a : 1; char b; };
// CHECK: *** Dumping AST Record Layout
// CHECK: 0 | struct D
// CHECK: 0 | (D vbtable pointer)
// CHECK: 4 | char a
// CHECK: 5 | char b
// CHECK: 8 | struct B0 (virtual base)
// CHECK: 8 | int a
// CHECK: | [sizeof=12, align=4
// CHECK: | nvsize=8, nvalign=4]
// CHECK-X64: *** Dumping AST Record Layout
// CHECK-X64: 0 | struct D
// CHECK-X64: 0 | (D vbtable pointer)
// CHECK-X64: 8 | char a
// CHECK-X64: 9 | char b
// CHECK-X64: 16 | struct B0 (virtual base)
// CHECK-X64: 16 | int a
// CHECK-X64: | [sizeof=24, align=8
// CHECK-X64: | nvsize=16, nvalign=8]
struct E : virtual B0, virtual B1 { long long : 1; };
// CHECK: *** Dumping AST Record Layout
// CHECK: 0 | struct E
// CHECK: 0 | (E vbtable pointer)
// CHECK: 8 | long long
// CHECK: 24 | struct B0 (virtual base)
// CHECK: 24 | int a
// CHECK: 36 | struct B1 (virtual base)
// CHECK: 36 | int a
// CHECK: | [sizeof=40, align=8
// CHECK: | nvsize=16, nvalign=8]
// CHECK-X64: *** Dumping AST Record Layout
// CHECK-X64: 0 | struct E
// CHECK-X64: 0 | (E vbtable pointer)
// CHECK-X64: 8 | long long
// CHECK-X64: 24 | struct B0 (virtual base)
// CHECK-X64: 24 | int a
// CHECK-X64: 36 | struct B1 (virtual base)
// CHECK-X64: 36 | int a
// CHECK-X64: | [sizeof=40, align=8
// CHECK-X64: | nvsize=16, nvalign=8]
int a[
sizeof(A)+
sizeof(B)+
sizeof(C)+
sizeof(D)];
sizeof(D)+
sizeof(E)];