r205933 - [MS-ABI] Update to alias-avoidance padding
Warren Hunt
whunt at google.com
Wed Apr 9 14:57:24 PDT 2014
Author: whunt
Date: Wed Apr 9 16:57:24 2014
New Revision: 205933
URL: http://llvm.org/viewvc/llvm-project?rev=205933&view=rev
Log:
[MS-ABI] Update to alias-avoidance padding
This patch changes how we determine if padding is needed between two
bases in msvc compatibility mode. Test cases included.
In addition, a very minor change to the printing of structures to ease
lit testing.
Modified:
cfe/trunk/lib/AST/RecordLayoutBuilder.cpp
cfe/trunk/test/Layout/ms-x86-alias-avoidance-padding.cpp
Modified: cfe/trunk/lib/AST/RecordLayoutBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/RecordLayoutBuilder.cpp?rev=205933&r1=205932&r2=205933&view=diff
==============================================================================
--- cfe/trunk/lib/AST/RecordLayoutBuilder.cpp (original)
+++ cfe/trunk/lib/AST/RecordLayoutBuilder.cpp Wed Apr 9 16:57:24 2014
@@ -2099,12 +2099,13 @@ static bool isMsLayout(const RecordDecl*
// * The ABI attempts to avoid aliasing of zero sized bases by adding padding
// between bases or vbases with specific properties. The criteria for
// additional padding between two bases is that the first base is zero sized
-// or has a zero sized subobject and the second base is zero sized or leads
-// with a zero sized base (sharing of vfptrs can reorder the layout of the
-// so the leading base is not always the first one declared). The padding
-// added for bases is 1 byte. The padding added for vbases depends on the
-// alignment of the object but is at least 4 bytes (in both 32 and 64 bit
-// modes).
+// or ends with a zero sized subobject and the second base is zero sized or
+// leads with a zero sized base (sharing of vfptrs can reorder the layout of
+// the so the leading base is not always the first one declared). This rule
+// is slightly buggy (conservative) because it doesn't take into account
+// fields that are not records. The padding added for bases is 1 byte. The
+// padding added for vbases depends on the alignment of the object but is at
+// least 4 bytes (in both 32 and 64 bit modes).
// * There is no concept of non-virtual alignment or any distinction between
// data size and non-virtual size.
// * __declspec(align) on bitfields has the effect of changing the bitfield's
@@ -2213,9 +2214,10 @@ public:
bool HasVBPtr : 1;
/// \brief Lets us know if we're in 64-bit mode
bool Is64BitMode : 1;
- /// \brief True if this class contains a zero sized member or base or a base
- /// with a zero sized member or base. Only used for MS-ABI.
- bool HasZeroSizedSubObject : 1;
+ /// \brief True if the last sub-object within the type is zero sized or the
+ /// object itself is zero sized. This *does not* count members that are not
+ /// records. Only used for MS-ABI.
+ bool EndsWithZeroSizedObject : 1;
/// \brief True if this class is zero sized or first base is zero sized or
/// has this property. Only used for MS-ABI.
bool LeadsWithZeroSizedBase : 1;
@@ -2231,8 +2233,7 @@ MicrosoftRecordLayoutBuilder::getAdjuste
if (!MaxFieldAlignment.isZero())
Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
// Track zero-sized subobjects here where it's already available.
- if (Layout.hasZeroSizedSubObject())
- HasZeroSizedSubObject = true;
+ EndsWithZeroSizedObject = Layout.hasZeroSizedSubObject();
// Respect required alignment, this is necessary because we may have adjusted
// the alignment in the case of pragam pack. Note that the required alignment
// doesn't actually apply to the struct alignment at this point.
@@ -2339,7 +2340,7 @@ void MicrosoftRecordLayoutBuilder::initi
void
MicrosoftRecordLayoutBuilder::initializeCXXLayout(const CXXRecordDecl *RD) {
- HasZeroSizedSubObject = false;
+ EndsWithZeroSizedObject = false;
LeadsWithZeroSizedBase = false;
HasOwnVFPtr = false;
HasVBPtr = false;
@@ -2617,7 +2618,6 @@ void MicrosoftRecordLayoutBuilder::layou
if (HasVtordisp)
Size = Size.RoundUpToAlignment(VtorDispAlignment) + VtorDispSize;
// Insert the virtual base.
- HasZeroSizedSubObject = false;
ElementInfo Info = getAdjustedElementInfo(BaseLayout);
CharUnits BaseOffset = Size.RoundUpToAlignment(Info.Alignment);
VBases.insert(std::make_pair(BaseDecl,
@@ -2637,7 +2637,7 @@ void MicrosoftRecordLayoutBuilder::final
}
// Zero-sized structures have size equal to their alignment.
if (Size.isZero()) {
- HasZeroSizedSubObject = true;
+ EndsWithZeroSizedObject = true;
LeadsWithZeroSizedBase = true;
Size = Alignment;
}
@@ -2750,7 +2750,7 @@ ASTContext::BuildMicrosoftASTRecordLayou
Builder.FieldOffsets.size(), Builder.NonVirtualSize,
Builder.Alignment, CharUnits::Zero(), Builder.PrimaryBase,
false, Builder.SharedVBPtrBase,
- Builder.HasZeroSizedSubObject, Builder.LeadsWithZeroSizedBase,
+ Builder.EndsWithZeroSizedObject, Builder.LeadsWithZeroSizedBase,
Builder.Bases, Builder.VBases);
} else {
Builder.layout(D);
@@ -3078,7 +3078,6 @@ static void DumpCXXRecordLayout(raw_ostr
PrintIndentNoOffset(OS, IndentLevel - 1);
OS << " nvsize=" << Layout.getNonVirtualSize().getQuantity();
OS << ", nvalign=" << Layout.getNonVirtualAlignment().getQuantity() << "]\n";
- OS << '\n';
}
void ASTContext::DumpRecordLayout(const RecordDecl *RD,
Modified: cfe/trunk/test/Layout/ms-x86-alias-avoidance-padding.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Layout/ms-x86-alias-avoidance-padding.cpp?rev=205933&r1=205932&r2=205933&view=diff
==============================================================================
--- cfe/trunk/test/Layout/ms-x86-alias-avoidance-padding.cpp (original)
+++ cfe/trunk/test/Layout/ms-x86-alias-avoidance-padding.cpp Wed Apr 9 16:57:24 2014
@@ -298,6 +298,257 @@ struct JC4 : JC1, JC2 {
// CHECK-X64-NEXT: | [sizeof=24, align=8
// CHECK-X64-NEXT: | nvsize=24, nvalign=8]
+struct RA {};
+struct RB { char c; };
+struct RV {};
+struct RW { char c; };
+struct RY { RY() { printf("%Id\n", (char*)this - buffer); } };
+struct RX0 : RB, RA {};
+struct RX1 : RA, RB {};
+struct RX2 : RA { char a; };
+struct RX3 : RA { RB a; };
+struct RX4 { RA a; char b; };
+struct RX5 { RA a; RB b; };
+struct RX6 : virtual RV { RB a; };
+struct RX7 : virtual RW { RA a; };
+struct RX8 : RA, virtual RW {};
+
+struct RZ0 : RX0, RY {};
+// CHECK: *** Dumping AST Record Layout
+// CHECK: *** Dumping AST Record Layout
+// CHECK: *** Dumping AST Record Layout
+// CHECK: *** Dumping AST Record Layout
+// CHECK: *** Dumping AST Record Layout
+// CHECK-NEXT: 0 | struct RZ0
+// CHECK-NEXT: 0 | struct RX0 (base)
+// CHECK-NEXT: 0 | struct RB (base)
+// CHECK-NEXT: 0 | char c
+// CHECK-NEXT: 1 | struct RA (base) (empty)
+// CHECK-NEXT: 2 | struct RY (base) (empty)
+// CHECK-NEXT: | [sizeof=2, align=1
+// CHECK-NEXT: | nvsize=2, nvalign=1]
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64-NEXT: 0 | struct RZ0
+// CHECK-X64-NEXT: 0 | struct RX0 (base)
+// CHECK-X64-NEXT: 0 | struct RB (base)
+// CHECK-X64-NEXT: 0 | char c
+// CHECK-X64-NEXT: 1 | struct RA (base) (empty)
+// CHECK-X64-NEXT: 2 | struct RY (base) (empty)
+// CHECK-X64-NEXT: | [sizeof=2, align=1
+// CHECK-X64-NEXT: | nvsize=2, nvalign=1]
+
+struct RZ1 : RX1, RY {};
+// CHECK: *** Dumping AST Record Layout
+// CHECK: *** Dumping AST Record Layout
+// CHECK-NEXT: 0 | struct RZ1
+// CHECK-NEXT: 0 | struct RX1 (base)
+// CHECK-NEXT: 0 | struct RA (base) (empty)
+// CHECK-NEXT: 0 | struct RB (base)
+// CHECK-NEXT: 0 | char c
+// CHECK-NEXT: 1 | struct RY (base) (empty)
+// CHECK-NEXT: | [sizeof=1, align=1
+// CHECK-NEXT: | nvsize=1, nvalign=1]
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64-NEXT: 0 | struct RZ1
+// CHECK-X64-NEXT: 0 | struct RX1 (base)
+// CHECK-X64-NEXT: 0 | struct RA (base) (empty)
+// CHECK-X64-NEXT: 0 | struct RB (base)
+// CHECK-X64-NEXT: 0 | char c
+// CHECK-X64-NEXT: 1 | struct RY (base) (empty)
+// CHECK-X64-NEXT: | [sizeof=1, align=1
+// CHECK-X64-NEXT: | nvsize=1, nvalign=1]
+
+struct RZ2 : RX2, RY {};
+// CHECK: *** Dumping AST Record Layout
+// CHECK: *** Dumping AST Record Layout
+// CHECK-NEXT: 0 | struct RZ2
+// CHECK-NEXT: 0 | struct RX2 (base)
+// CHECK-NEXT: 0 | struct RA (base) (empty)
+// CHECK-NEXT: 0 | char a
+// CHECK-NEXT: 2 | struct RY (base) (empty)
+// CHECK-NEXT: | [sizeof=2, align=1
+// CHECK-NEXT: | nvsize=2, nvalign=1]
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64-NEXT: 0 | struct RZ2
+// CHECK-X64-NEXT: 0 | struct RX2 (base)
+// CHECK-X64-NEXT: 0 | struct RA (base) (empty)
+// CHECK-X64-NEXT: 0 | char a
+// CHECK-X64-NEXT: 2 | struct RY (base) (empty)
+// CHECK-X64-NEXT: | [sizeof=2, align=1
+// CHECK-X64-NEXT: | nvsize=2, nvalign=1]
+
+struct RZ3 : RX3, RY {};
+// CHECK: *** Dumping AST Record Layout
+// CHECK: *** Dumping AST Record Layout
+// CHECK-NEXT: 0 | struct RZ3
+// CHECK-NEXT: 0 | struct RX3 (base)
+// CHECK-NEXT: 0 | struct RA (base) (empty)
+// CHECK-NEXT: 0 | struct RB a
+// CHECK-NEXT: 0 | char c
+// CHECK-NEXT: | [sizeof=1, align=1
+// CHECK-NEXT: | nvsize=1, nvalign=1]
+// CHECK-NEXT: 1 | struct RY (base) (empty)
+// CHECK-NEXT: | [sizeof=1, align=1
+// CHECK-NEXT: | nvsize=1, nvalign=1]
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64-NEXT: 0 | struct RZ3
+// CHECK-X64-NEXT: 0 | struct RX3 (base)
+// CHECK-X64-NEXT: 0 | struct RA (base) (empty)
+// CHECK-X64-NEXT: 0 | struct RB a
+// CHECK-X64-NEXT: 0 | char c
+// CHECK-X64-NEXT: | [sizeof=1, align=1
+// CHECK-X64-NEXT: | nvsize=1, nvalign=1]
+// CHECK-X64-NEXT: 1 | struct RY (base) (empty)
+// CHECK-X64-NEXT: | [sizeof=1, align=1
+// CHECK-X64-NEXT: | nvsize=1, nvalign=1]
+
+struct RZ4 : RX4, RY {};
+// CHECK: *** Dumping AST Record Layout
+// CHECK: *** Dumping AST Record Layout
+// CHECK-NEXT: 0 | struct RZ4
+// CHECK-NEXT: 0 | struct RX4 (base)
+// CHECK-NEXT: 0 | struct RA a (empty)
+// CHECK-NEXT: | [sizeof=1, align=1
+// CHECK-NEXT: | nvsize=0, nvalign=1]
+// CHECK-NEXT: 1 | char b
+// CHECK-NEXT: 3 | struct RY (base) (empty)
+// CHECK-NEXT: | [sizeof=3, align=1
+// CHECK-NEXT: | nvsize=3, nvalign=1]
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64-NEXT: 0 | struct RZ4
+// CHECK-X64-NEXT: 0 | struct RX4 (base)
+// CHECK-X64-NEXT: 0 | struct RA a (empty)
+// CHECK-X64-NEXT: | [sizeof=1, align=1
+// CHECK-X64-NEXT: | nvsize=0, nvalign=1]
+// CHECK-X64-NEXT: 1 | char b
+// CHECK-X64-NEXT: 3 | struct RY (base) (empty)
+// CHECK-X64-NEXT: | [sizeof=3, align=1
+// CHECK-X64-NEXT: | nvsize=3, nvalign=1]
+
+struct RZ5 : RX5, RY {};
+// CHECK: *** Dumping AST Record Layout
+// CHECK: *** Dumping AST Record Layout
+// CHECK-NEXT: 0 | struct RZ5
+// CHECK-NEXT: 0 | struct RX5 (base)
+// CHECK-NEXT: 0 | struct RA a (empty)
+// CHECK-NEXT: | [sizeof=1, align=1
+// CHECK-NEXT: | nvsize=0, nvalign=1]
+// CHECK-NEXT: 1 | struct RB b
+// CHECK-NEXT: 1 | char c
+// CHECK-NEXT: | [sizeof=1, align=1
+// CHECK-NEXT: | nvsize=1, nvalign=1]
+// CHECK-NEXT: 2 | struct RY (base) (empty)
+// CHECK-NEXT: | [sizeof=2, align=1
+// CHECK-NEXT: | nvsize=2, nvalign=1]
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64-NEXT: 0 | struct RZ5
+// CHECK-X64-NEXT: 0 | struct RX5 (base)
+// CHECK-X64-NEXT: 0 | struct RA a (empty)
+// CHECK-X64-NEXT: | [sizeof=1, align=1
+// CHECK-X64-NEXT: | nvsize=0, nvalign=1]
+// CHECK-X64-NEXT: 1 | struct RB b
+// CHECK-X64-NEXT: 1 | char c
+// CHECK-X64-NEXT: | [sizeof=1, align=1
+// CHECK-X64-NEXT: | nvsize=1, nvalign=1]
+// CHECK-X64-NEXT: 2 | struct RY (base) (empty)
+// CHECK-X64-NEXT: | [sizeof=2, align=1
+// CHECK-X64-NEXT: | nvsize=2, nvalign=1]
+
+struct RZ6 : RX6, RY {};
+// CHECK: *** Dumping AST Record Layout
+// CHECK: *** Dumping AST Record Layout
+// CHECK: *** Dumping AST Record Layout
+// CHECK-NEXT: 0 | struct RZ6
+// CHECK-NEXT: 0 | struct RX6 (base)
+// CHECK-NEXT: 0 | (RX6 vbtable pointer)
+// CHECK-NEXT: 4 | struct RB a
+// CHECK-NEXT: 4 | char c
+// CHECK-NEXT: | [sizeof=1, align=1
+// CHECK-NEXT: | nvsize=1, nvalign=1]
+// CHECK-NEXT: 9 | struct RY (base) (empty)
+// CHECK-NEXT: 12 | struct RV (virtual base) (empty)
+// CHECK-NEXT: | [sizeof=12, align=4
+// CHECK-NEXT: | nvsize=12, nvalign=4]
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64-NEXT: 0 | struct RZ6
+// CHECK-X64-NEXT: 0 | struct RX6 (base)
+// CHECK-X64-NEXT: 0 | (RX6 vbtable pointer)
+// CHECK-X64-NEXT: 8 | struct RB a
+// CHECK-X64-NEXT: 8 | char c
+// CHECK-X64-NEXT: | [sizeof=1, align=1
+// CHECK-X64-NEXT: | nvsize=1, nvalign=1]
+// CHECK-X64-NEXT: 17 | struct RY (base) (empty)
+// CHECK-X64-NEXT: 24 | struct RV (virtual base) (empty)
+// CHECK-X64-NEXT: | [sizeof=24, align=8
+// CHECK-X64-NEXT: | nvsize=24, nvalign=8]
+
+struct RZ7 : RX7, RY {};
+// CHECK: *** Dumping AST Record Layout
+// CHECK: *** Dumping AST Record Layout
+// CHECK: *** Dumping AST Record Layout
+// CHECK-NEXT: 0 | struct RZ7
+// CHECK-NEXT: 0 | struct RX7 (base)
+// CHECK-NEXT: 0 | (RX7 vbtable pointer)
+// CHECK-NEXT: 4 | struct RA a (empty)
+// CHECK-NEXT: | [sizeof=1, align=1
+// CHECK-NEXT: | nvsize=0, nvalign=1]
+// CHECK-NEXT: 8 | struct RY (base) (empty)
+// CHECK-NEXT: 8 | struct RW (virtual base)
+// CHECK-NEXT: 8 | char c
+// CHECK-NEXT: | [sizeof=9, align=4
+// CHECK-NEXT: | nvsize=8, nvalign=4]
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64-NEXT: 0 | struct RZ7
+// CHECK-X64-NEXT: 0 | struct RX7 (base)
+// CHECK-X64-NEXT: 0 | (RX7 vbtable pointer)
+// CHECK-X64-NEXT: 8 | struct RA a (empty)
+// CHECK-X64-NEXT: | [sizeof=1, align=1
+// CHECK-X64-NEXT: | nvsize=0, nvalign=1]
+// CHECK-X64-NEXT: 16 | struct RY (base) (empty)
+// CHECK-X64-NEXT: 16 | struct RW (virtual base)
+// CHECK-X64-NEXT: 16 | char c
+// CHECK-X64-NEXT: | [sizeof=24, align=8
+// CHECK-X64-NEXT: | nvsize=16, nvalign=8]
+
+struct RZ8 : RX8, RY {};
+// CHECK: *** Dumping AST Record Layout
+// CHECK: *** Dumping AST Record Layout
+// CHECK-NEXT: 0 | struct RZ8
+// CHECK-NEXT: 0 | struct RX8 (base)
+// CHECK-NEXT: 4 | struct RA (base) (empty)
+// CHECK-NEXT: 0 | (RX8 vbtable pointer)
+// CHECK-NEXT: 4 | struct RY (base) (empty)
+// CHECK-NEXT: 4 | struct RW (virtual base)
+// CHECK-NEXT: 4 | char c
+// CHECK-NEXT: | [sizeof=5, align=4
+// CHECK-NEXT: | nvsize=4, nvalign=4]
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64-NEXT: 0 | struct RZ8
+// CHECK-X64-NEXT: 0 | struct RX8 (base)
+// CHECK-X64-NEXT: 8 | struct RA (base) (empty)
+// CHECK-X64-NEXT: 0 | (RX8 vbtable pointer)
+// CHECK-X64-NEXT: 8 | struct RY (base) (empty)
+// CHECK-X64-NEXT: 8 | struct RW (virtual base)
+// CHECK-X64-NEXT: 8 | char c
+// CHECK-X64-NEXT: | [sizeof=16, align=8
+// CHECK-X64-NEXT: | nvsize=8, nvalign=8]
+
+
+
int a[
sizeof(AT3) +
sizeof(BT3) +
@@ -305,4 +556,13 @@ sizeof(T3) +
sizeof(E) +
sizeof(F) +
sizeof(JC4) +
+sizeof(RZ0) +
+sizeof(RZ1) +
+sizeof(RZ2) +
+sizeof(RZ3) +
+sizeof(RZ4) +
+sizeof(RZ5) +
+sizeof(RZ6) +
+sizeof(RZ7) +
+sizeof(RZ8) +
0];
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