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Microsoft Record Layout: zero sized base after base with vbtbl fix

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Microsoft adds an extra byte of padding before laying out zero sized 
non-virtual bases if the non-virtual base before it contains a vbptr.  
This patch adds the same behavior to clang.

Differential Revision: http://llvm-reviews.chandlerc.com/D2106

llvm-svn: 195158
This commit is contained in:
Warren Hunt
2013-11-19 22:11:09 +00:00
parent 45115f877c
commit c0df47dfed
2 changed files with 227 additions and 0 deletions
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11
clang/lib/AST/RecordLayoutBuilder.cpp
View File

@@ -2017,6 +2017,8 @@ static bool isMsLayout(const RecordDecl* D) {
// * 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.
// * 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.
namespace {
@@ -2141,6 +2143,8 @@ public:
bool LastBaseWasEmpty;
/// \brief Lets us know if we're in 64-bit mode
bool Is64BitMode;
/// \brief True if the last non-virtual base has a vbptr.
bool LastNonVirtualBaseHasVBPtr;
};
} // namespace
@@ -2304,6 +2308,7 @@ void
MicrosoftRecordLayoutBuilder::layoutNonVirtualBases(const CXXRecordDecl *RD) {
LazyEmptyBase = 0;
LastBaseWasEmpty = false;
LastNonVirtualBaseHasVBPtr = false;
// Lay out the primary base first.
if (PrimaryBase)
@@ -2331,6 +2336,10 @@ MicrosoftRecordLayoutBuilder::layoutNonVirtualBase(const CXXRecordDecl *RD) {
const ASTRecordLayout &LazyLayout =
Context.getASTRecordLayout(LazyEmptyBase);
Size = Size.RoundUpToAlignment(LazyLayout.getAlignment());
// If the last non-virtual base has a vbptr we add a byte of padding for no
// obvious reason.
if (LastNonVirtualBaseHasVBPtr)
Size++;
Bases.insert(std::make_pair(LazyEmptyBase, Size));
// Empty bases only consume space when followed by another empty base.
if (RD && Layout->getNonVirtualSize().isZero()) {
@@ -2338,6 +2347,7 @@ MicrosoftRecordLayoutBuilder::layoutNonVirtualBase(const CXXRecordDecl *RD) {
Size++;
}
LazyEmptyBase = 0;
LastNonVirtualBaseHasVBPtr = false;
}
// RD is null when flushing the final lazy base.
@@ -2356,6 +2366,7 @@ MicrosoftRecordLayoutBuilder::layoutNonVirtualBase(const CXXRecordDecl *RD) {
// Note: we don't update alignment here because it was accounted
// for during initalization.
LastBaseWasEmpty = false;
LastNonVirtualBaseHasVBPtr = Layout->hasVBPtr();
}
void MicrosoftRecordLayoutBuilder::layoutVBPtr(const CXXRecordDecl *RD) {

216
clang/test/Layout/ms-x86-empty-base-after-base-with-vbptr.cpp Normal file
View File

@@ -0,0 +1,216 @@
// RUN: %clang_cc1 -fno-rtti -emit-llvm-only -triple i686-pc-win32 -fdump-record-layouts -cxx-abi microsoft %s 2>/dev/null \
// RUN: | FileCheck %s
// RUN: %clang_cc1 -fno-rtti -emit-llvm-only -triple x86_64-pc-win32 -fdump-record-layouts -cxx-abi microsoft %s 2>/dev/null \
// RUN: | FileCheck %s -check-prefix CHECK-X64
struct U { char a; };
struct V { };
struct W { };
struct X : virtual V { char a; };
struct Y : virtual V { char a; };
struct Z : Y { };
struct A : X, W { char a; };
// CHECK: *** Dumping AST Record Layout
// CHECK: 0 | struct A
// CHECK: 0 | struct X (base)
// CHECK: 0 | (X vbtable pointer)
// CHECK: 4 | char a
// CHECK: 9 | struct W (base) (empty)
// CHECK: 9 | char a
// CHECK: 12 | struct V (virtual base) (empty)
// CHECK: | [sizeof=12, align=4
// CHECK: | nvsize=12, nvalign=4]
// CHECK-X64: *** Dumping AST Record Layout
// CHECK-X64: 0 | struct A
// CHECK-X64: 0 | struct X (base)
// CHECK-X64: 0 | (X vbtable pointer)
// CHECK-X64: 8 | char a
// CHECK-X64: 17 | struct W (base) (empty)
// CHECK-X64: 17 | char a
// CHECK-X64: 24 | struct V (virtual base) (empty)
// CHECK-X64: | [sizeof=24, align=8
// CHECK-X64: | nvsize=24, nvalign=8]
struct B : X, U, W { char a; };
// CHECK: *** Dumping AST Record Layout
// CHECK: 0 | struct B
// CHECK: 0 | struct X (base)
// CHECK: 0 | (X vbtable pointer)
// CHECK: 4 | char a
// CHECK: 8 | struct U (base)
// CHECK: 8 | char a
// CHECK: 9 | struct W (base) (empty)
// CHECK: 9 | char a
// CHECK: 12 | struct V (virtual base) (empty)
// CHECK: | [sizeof=12, align=4
// CHECK: | nvsize=12, nvalign=4]
// CHECK-X64: *** Dumping AST Record Layout
// CHECK-X64: 0 | struct B
// CHECK-X64: 0 | struct X (base)
// CHECK-X64: 0 | (X vbtable pointer)
// CHECK-X64: 8 | char a
// CHECK-X64: 16 | struct U (base)
// CHECK-X64: 16 | char a
// CHECK-X64: 17 | struct W (base) (empty)
// CHECK-X64: 17 | char a
// CHECK-X64: 24 | struct V (virtual base) (empty)
// CHECK-X64: | [sizeof=24, align=8
// CHECK-X64: | nvsize=24, nvalign=8]
struct C : X, V, W { char a; };
// CHECK: *** Dumping AST Record Layout
// CHECK: 0 | struct C
// CHECK: 0 | struct X (base)
// CHECK: 0 | (X vbtable pointer)
// CHECK: 4 | char a
// CHECK: 9 | struct V (base) (empty)
// CHECK: 10 | struct W (base) (empty)
// CHECK: 10 | char a
// CHECK: 12 | struct V (virtual base) (empty)
// CHECK: | [sizeof=12, align=4
// CHECK: | nvsize=12, nvalign=4]
// CHECK-X64: *** Dumping AST Record Layout
// CHECK-X64: 0 | struct C
// CHECK-X64: 0 | struct X (base)
// CHECK-X64: 0 | (X vbtable pointer)
// CHECK-X64: 8 | char a
// CHECK-X64: 17 | struct V (base) (empty)
// CHECK-X64: 18 | struct W (base) (empty)
// CHECK-X64: 18 | char a
// CHECK-X64: 24 | struct V (virtual base) (empty)
// CHECK-X64: | [sizeof=24, align=8
// CHECK-X64: | nvsize=24, nvalign=8]
struct D : X, U, V, W { char a; };
// CHECK: *** Dumping AST Record Layout
// CHECK: 0 | struct D
// CHECK: 0 | struct X (base)
// CHECK: 0 | (X vbtable pointer)
// CHECK: 4 | char a
// CHECK: 8 | struct U (base)
// CHECK: 8 | char a
// CHECK: 9 | struct V (base) (empty)
// CHECK: 10 | struct W (base) (empty)
// CHECK: 10 | char a
// CHECK: 12 | struct V (virtual base) (empty)
// CHECK: | [sizeof=12, align=4
// CHECK: | nvsize=12, nvalign=4]
// CHECK-X64: *** Dumping AST Record Layout
// CHECK-X64: 0 | struct D
// CHECK-X64: 0 | struct X (base)
// CHECK-X64: 0 | (X vbtable pointer)
// CHECK-X64: 8 | char a
// CHECK-X64: 16 | struct U (base)
// CHECK-X64: 16 | char a
// CHECK-X64: 17 | struct V (base) (empty)
// CHECK-X64: 18 | struct W (base) (empty)
// CHECK-X64: 18 | char a
// CHECK-X64: 24 | struct V (virtual base) (empty)
// CHECK-X64: | [sizeof=24, align=8
// CHECK-X64: | nvsize=24, nvalign=8]
struct E : X, U, Y, V, W { char a; };
// CHECK: *** Dumping AST Record Layout
// CHECK: 0 | struct E
// CHECK: 0 | struct X (base)
// CHECK: 0 | (X vbtable pointer)
// CHECK: 4 | char a
// CHECK: 8 | struct U (base)
// CHECK: 8 | char a
// CHECK: 12 | struct Y (base)
// CHECK: 12 | (Y vbtable pointer)
// CHECK: 16 | char a
// CHECK: 21 | struct V (base) (empty)
// CHECK: 22 | struct W (base) (empty)
// CHECK: 22 | char a
// CHECK: 24 | struct V (virtual base) (empty)
// CHECK: | [sizeof=24, align=4
// CHECK: | nvsize=24, nvalign=4]
// CHECK-X64: *** Dumping AST Record Layout
// CHECK-X64: 0 | struct E
// CHECK-X64: 0 | struct X (base)
// CHECK-X64: 0 | (X vbtable pointer)
// CHECK-X64: 8 | char a
// CHECK-X64: 16 | struct U (base)
// CHECK-X64: 16 | char a
// CHECK-X64: 24 | struct Y (base)
// CHECK-X64: 24 | (Y vbtable pointer)
// CHECK-X64: 32 | char a
// CHECK-X64: 41 | struct V (base) (empty)
// CHECK-X64: 42 | struct W (base) (empty)
// CHECK-X64: 42 | char a
// CHECK-X64: 48 | struct V (virtual base) (empty)
// CHECK-X64: | [sizeof=48, align=8
// CHECK-X64: | nvsize=48, nvalign=8]
struct F : Z, W { char a; };
// CHECK: *** Dumping AST Record Layout
// CHECK: 0 | struct F
// CHECK: 0 | struct Z (base)
// CHECK: 0 | struct Y (base)
// CHECK: 0 | (Y vbtable pointer)
// CHECK: 4 | char a
// CHECK: 9 | struct W (base) (empty)
// CHECK: 9 | char a
// CHECK: 12 | struct V (virtual base) (empty)
// CHECK: | [sizeof=12, align=4
// CHECK: | nvsize=12, nvalign=4]
// CHECK-X64: *** Dumping AST Record Layout
// CHECK-X64: 0 | struct F
// CHECK-X64: 0 | struct Z (base)
// CHECK-X64: 0 | struct Y (base)
// CHECK-X64: 0 | (Y vbtable pointer)
// CHECK-X64: 8 | char a
// CHECK-X64: 17 | struct W (base) (empty)
// CHECK-X64: 17 | char a
// CHECK-X64: 24 | struct V (virtual base) (empty)
// CHECK-X64: | [sizeof=24, align=8
// CHECK-X64: | nvsize=24, nvalign=8]
struct G : X, W, Y, V { char a; };
// CHECK: *** Dumping AST Record Layout
// CHECK: 0 | struct G
// CHECK: 0 | struct X (base)
// CHECK: 0 | (X vbtable pointer)
// CHECK: 4 | char a
// CHECK: 9 | struct W (base) (empty)
// CHECK: 12 | struct Y (base)
// CHECK: 12 | (Y vbtable pointer)
// CHECK: 16 | char a
// CHECK: 21 | struct V (base) (empty)
// CHECK: 21 | char a
// CHECK: 24 | struct V (virtual base) (empty)
// CHECK: | [sizeof=24, align=4
// CHECK: | nvsize=24, nvalign=4]
// CHECK-X64: *** Dumping AST Record Layout
// CHECK-X64: 0 | struct G
// CHECK-X64: 0 | struct X (base)
// CHECK-X64: 0 | (X vbtable pointer)
// CHECK-X64: 8 | char a
// CHECK-X64: 17 | struct W (base) (empty)
// CHECK-X64: 24 | struct Y (base)
// CHECK-X64: 24 | (Y vbtable pointer)
// CHECK-X64: 32 | char a
// CHECK-X64: 41 | struct V (base) (empty)
// CHECK-X64: 41 | char a
// CHECK-X64: 48 | struct V (virtual base) (empty)
// CHECK-X64: | [sizeof=48, align=8
// CHECK-X64: | nvsize=48, nvalign=8]
int a[
sizeof(A)+
sizeof(B)+
sizeof(C)+
sizeof(D)+
sizeof(E)+
sizeof(F)+
sizeof(G)];