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Revert "[CodeGen] Add initial support for union members in TBAA" 

This reverts commit r319413. See PR35503.

We can't use "union member" as the access type here like this.

llvm-svn: 319629
This commit is contained in:
Hal Finkel 2017-12-03 03:10:13 +00:00
parent f3470e1ed4
commit a5986b9e91
6 changed files with 37 additions and 174 deletions
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31
clang/lib/CodeGen/CGExpr.cpp
View File

@ -3723,6 +3723,9 @@ LValue CodeGenFunction::EmitLValueForField(LValue base,
if (base.getTBAAInfo().isMayAlias() ||
rec->hasAttr<MayAliasAttr>() || FieldType->isVectorType()) {
FieldTBAAInfo = TBAAAccessInfo::getMayAliasInfo();
} else if (rec->isUnion()) {
// TODO: Support TBAA for unions.
FieldTBAAInfo = TBAAAccessInfo::getMayAliasInfo();
} else {
// If no base type been assigned for the base access, then try to generate
// one for this base lvalue.
@ -3733,26 +3736,16 @@ LValue CodeGenFunction::EmitLValueForField(LValue base,
"Nonzero offset for an access with no base type!");
}
// All union members are encoded to be of the same special type.
if (FieldTBAAInfo.BaseType && rec->isUnion())
FieldTBAAInfo = TBAAAccessInfo::getUnionMemberInfo(FieldTBAAInfo.BaseType,
FieldTBAAInfo.Offset,
FieldTBAAInfo.Size);
// Adjust offset to be relative to the base type.
const ASTRecordLayout &Layout =
getContext().getASTRecordLayout(field->getParent());
unsigned CharWidth = getContext().getCharWidth();
if (FieldTBAAInfo.BaseType)
FieldTBAAInfo.Offset +=
Layout.getFieldOffset(field->getFieldIndex()) / CharWidth;
// For now we describe accesses to direct and indirect union members as if
// they were at the offset of their outermost enclosing union.
if (!FieldTBAAInfo.isUnionMember()) {
// Adjust offset to be relative to the base type.
const ASTRecordLayout &Layout =
getContext().getASTRecordLayout(field->getParent());
unsigned CharWidth = getContext().getCharWidth();
if (FieldTBAAInfo.BaseType)
FieldTBAAInfo.Offset +=
Layout.getFieldOffset(field->getFieldIndex()) / CharWidth;
// Update the final access type.
FieldTBAAInfo.AccessType = CGM.getTBAATypeInfo(FieldType);
}
// Update the final access type.
FieldTBAAInfo.AccessType = CGM.getTBAATypeInfo(FieldType);
}
Address addr = base.getAddress();

5
clang/lib/CodeGen/CodeGenModule.h
View File

@ -688,9 +688,8 @@ public:
/// getTBAAInfoForSubobject - Get TBAA information for an access with a given
/// base lvalue.
TBAAAccessInfo getTBAAInfoForSubobject(LValue Base, QualType AccessType) {
TBAAAccessInfo TBAAInfo = Base.getTBAAInfo();
if (TBAAInfo.isMayAlias() || TBAAInfo.isUnionMember())
return TBAAInfo;
if (Base.getTBAAInfo().isMayAlias())
return TBAAAccessInfo::getMayAliasInfo();
return getTBAAAccessInfo(AccessType);
}

42
clang/lib/CodeGen/CodeGenTBAA.cpp
View File

@ -74,10 +74,6 @@ llvm::MDNode *CodeGenTBAA::getChar() {
return Char;
}
llvm::MDNode *CodeGenTBAA::getUnionMemberType(uint64_t Size) {
return createScalarTypeNode("union member", getChar(), Size);
}
static bool TypeHasMayAlias(QualType QTy) {
// Tagged types have declarations, and therefore may have attributes.
if (const TagType *TTy = dyn_cast<TagType>(QTy))
@ -105,8 +101,9 @@ static bool isValidBaseType(QualType QTy) {
return false;
if (RD->hasFlexibleArrayMember())
return false;
// For now, we do not allow interface classes to be base access types.
if (RD->isStruct() || RD->isClass() || RD->isUnion())
// RD can be struct, union, class, interface or enum.
// For now, we only handle struct and class.
if (RD->isStruct() || RD->isClass())
return true;
}
return false;
@ -280,27 +277,18 @@ llvm::MDNode *CodeGenTBAA::getBaseTypeInfoHelper(const Type *Ty) {
const RecordDecl *RD = TTy->getDecl()->getDefinition();
const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
SmallVector<llvm::MDBuilder::TBAAStructField, 4> Fields;
if (RD->isUnion()) {
// Unions are represented as structures with a single member that has a
// special type and occupies the whole object.
uint64_t Size = Context.getTypeSizeInChars(Ty).getQuantity();
llvm::MDNode *TypeNode = getUnionMemberType(Size);
Fields.push_back(llvm::MDBuilder::TBAAStructField(/* Offset= */ 0, Size,
TypeNode));
} else {
for (FieldDecl *Field : RD->fields()) {
QualType FieldQTy = Field->getType();
llvm::MDNode *TypeNode = isValidBaseType(FieldQTy) ?
getBaseTypeInfo(FieldQTy) : getTypeInfo(FieldQTy);
if (!TypeNode)
return nullptr;
for (FieldDecl *Field : RD->fields()) {
QualType FieldQTy = Field->getType();
llvm::MDNode *TypeNode = isValidBaseType(FieldQTy) ?
getBaseTypeInfo(FieldQTy) : getTypeInfo(FieldQTy);
if (!TypeNode)
return BaseTypeMetadataCache[Ty] = nullptr;
uint64_t BitOffset = Layout.getFieldOffset(Field->getFieldIndex());
uint64_t Offset = Context.toCharUnitsFromBits(BitOffset).getQuantity();
uint64_t Size = Context.getTypeSizeInChars(FieldQTy).getQuantity();
Fields.push_back(llvm::MDBuilder::TBAAStructField(Offset, Size,
TypeNode));
}
uint64_t BitOffset = Layout.getFieldOffset(Field->getFieldIndex());
uint64_t Offset = Context.toCharUnitsFromBits(BitOffset).getQuantity();
uint64_t Size = Context.getTypeSizeInChars(FieldQTy).getQuantity();
Fields.push_back(llvm::MDBuilder::TBAAStructField(Offset, Size,
TypeNode));
}
SmallString<256> OutName;
@ -345,8 +333,6 @@ llvm::MDNode *CodeGenTBAA::getAccessTagInfo(TBAAAccessInfo Info) {
if (Info.isMayAlias())
Info = TBAAAccessInfo(getChar(), Info.Size);
else if (Info.isUnionMember())
Info.AccessType = getUnionMemberType(Info.Size);
if (!Info.AccessType)
return nullptr;

19
clang/lib/CodeGen/CodeGenTBAA.h
View File

@ -34,10 +34,9 @@ class CGRecordLayout;
// TBAAAccessKind - A kind of TBAA memory access descriptor.
enum class TBAAAccessKind : unsigned {
Ordinary, // An ordinary memory access.
MayAlias, // An access that may alias with any other accesses.
Incomplete, // Used to designate pointee values of incomplete types.
UnionMember, // An access to a direct or indirect union member.
Ordinary,
MayAlias,
Incomplete,
};
// TBAAAccessInfo - Describes a memory access in terms of TBAA.
@ -78,14 +77,6 @@ struct TBAAAccessInfo {
bool isIncomplete() const { return Kind == TBAAAccessKind::Incomplete; }
static TBAAAccessInfo getUnionMemberInfo(llvm::MDNode *BaseType,
uint64_t Offset, uint64_t Size) {
return TBAAAccessInfo(TBAAAccessKind::UnionMember, BaseType,
/* AccessType= */ nullptr, Offset, Size);
}
bool isUnionMember() const { return Kind == TBAAAccessKind::UnionMember; }
bool operator==(const TBAAAccessInfo &Other) const {
return Kind == Other.Kind &&
BaseType == Other.BaseType &&
@ -157,10 +148,6 @@ class CodeGenTBAA {
/// considered to be equivalent to it.
llvm::MDNode *getChar();
/// getUnionMemberType - Get metadata that represents the type of union
/// members.
llvm::MDNode *getUnionMemberType(uint64_t Size);
/// CollectFields - Collect information about the fields of a type for
/// !tbaa.struct metadata formation. Return false for an unsupported type.
bool CollectFields(uint64_t BaseOffset,

100
clang/test/CodeGen/tbaa-union.cpp
View File

@ -1,100 +0,0 @@
// RUN: %clang_cc1 -triple x86_64-linux -O1 -disable-llvm-passes %s -emit-llvm -o - | FileCheck %s
//
// Check that we generate correct TBAA information for accesses to union
// members.
struct X {
int a, b;
int arr[3];
int c, d;
};
union U {
int i;
X x;
int j;
};
struct S {
U u, v;
};
union N {
int i;
S s;
int j;
};
struct R {
N n, m;
};
int f1(U *p) {
// CHECK-LABEL: _Z2f1P1U
// CHECK: load i32, i32* {{.*}}, !tbaa [[TAG_U_j:!.*]]
return p->j;
}
int f2(S *p) {
// CHECK-LABEL: _Z2f2P1S
// CHECK: load i32, i32* {{.*}}, !tbaa [[TAG_S_u_i:!.*]]
return p->u.i;
}
int f3(S *p) {
// CHECK-LABEL: _Z2f3P1S
// CHECK: load i32, i32* {{.*}}, !tbaa [[TAG_S_v_j:!.*]]
return p->v.j;
}
int f4(S *p) {
// CHECK-LABEL: _Z2f4P1S
// CHECK: load i32, i32* {{.*}}, !tbaa [[TAG_S_u_x_b:!.*]]
return p->u.x.b;
}
int f5(S *p) {
// CHECK-LABEL: _Z2f5P1S
// CHECK: load i32, i32* {{.*}}, !tbaa [[TAG_S_v_x_b:!.*]]
return p->v.x.b;
}
int f6(S *p) {
// CHECK-LABEL: _Z2f6P1S
// CHECK: load i32, i32* {{.*}}, !tbaa [[TAG_S_u_x_arr:!.*]]
return p->u.x.arr[1];
}
int f7(S *p) {
// CHECK-LABEL: _Z2f7P1S
// CHECK: load i32, i32* {{.*}}, !tbaa [[TAG_S_v_x_arr:!.*]]
return p->v.x.arr[1];
}
int f8(N *p) {
// CHECK-LABEL: _Z2f8P1N
// CHECK: load i32, i32* {{.*}}, !tbaa [[TAG_N_s_v_x_c:!.*]]
return p->s.v.x.c;
}
int f9(R *p) {
// CHECK-LABEL: _Z2f9P1R
// CHECK: load i32, i32* {{.*}}, !tbaa [[TAG_R_m_s_v_x_c:!.*]]
return p->m.s.v.x.c;
}
// CHECK-DAG: [[TAG_U_j]] = !{[[TYPE_U:!.*]], [[TYPE_union_member:!.*]], i64 0}
// CHECK-DAG: [[TAG_S_u_i]] = !{[[TYPE_S:!.*]], [[TYPE_union_member]], i64 0}
// CHECK-DAG: [[TAG_S_u_x_b]] = !{[[TYPE_S:!.*]], [[TYPE_union_member]], i64 0}
// CHECK-DAG: [[TAG_S_u_x_arr]] = !{[[TYPE_S:!.*]], [[TYPE_union_member]], i64 0}
// CHECK-DAG: [[TAG_S_v_j]] = !{[[TYPE_S:!.*]], [[TYPE_union_member]], i64 28}
// CHECK-DAG: [[TAG_S_v_x_b]] = !{[[TYPE_S:!.*]], [[TYPE_union_member]], i64 28}
// CHECK-DAG: [[TAG_S_v_x_arr]] = !{[[TYPE_S:!.*]], [[TYPE_union_member]], i64 28}
// CHECK-DAG: [[TAG_N_s_v_x_c]] = !{[[TYPE_N:!.*]], [[TYPE_union_member]], i64 0}
// CHECK-DAG: [[TAG_R_m_s_v_x_c]] = !{[[TYPE_R:!.*]], [[TYPE_union_member]], i64 56}
// CHECK-DAG: [[TYPE_U]] = !{!"_ZTS1U", [[TYPE_union_member]], i64 0}
// CHECK-DAG: [[TYPE_S]] = !{!"_ZTS1S", [[TYPE_U]], i64 0, [[TYPE_U]], i64 28}
// CHECK-DAG: [[TYPE_N]] = !{!"_ZTS1N", [[TYPE_union_member]], i64 0}
// CHECK-DAG: [[TYPE_R]] = !{!"_ZTS1R", [[TYPE_N]], i64 0, [[TYPE_N]], i64 56}
// CHECK-DAG: [[TYPE_union_member]] = !{!"union member", [[TYPE_char:!.*]], i64 0}
// CHECK-DAG: [[TYPE_char]] = !{!"omnipotent char", {{.*}}, i64 0}

14
clang/test/CodeGen/union-tbaa1.c
View File

@ -15,32 +15,30 @@ void fred(unsigned Num, int Vec[2], int *Index, int Arr[4][2]) {
// But no tbaa for the two stores:
// CHECK: %uw[[UW1:[0-9]*]] = getelementptr
// CHECK: store{{.*}}%uw[[UW1]]
// CHECK: tbaa [[TAG_vect32_union_member:![0-9]+]]
// CHECK: tbaa ![[OCPATH:[0-9]+]]
// There will be a load after the store, and it will use tbaa. Make sure
// the check-not above doesn't find it:
// CHECK: load
Tmp[*Index][0].uw = Arr[*Index][0] * Num;
// CHECK: %uw[[UW2:[0-9]*]] = getelementptr
// CHECK: store{{.*}}%uw[[UW2]]
// CHECK: tbaa [[TAG_vect32_union_member]]
// CHECK: tbaa ![[OCPATH]]
Tmp[*Index][1].uw = Arr[*Index][1] * Num;
// Same here, don't generate tbaa for the loads:
// CHECK: %uh[[UH1:[0-9]*]] = bitcast %union.vect32
// CHECK: %arrayidx[[AX1:[0-9]*]] = getelementptr{{.*}}%uh[[UH1]]
// CHECK: load i16, i16* %arrayidx[[AX1]]
// CHECK: tbaa [[TAG_vect32_union_member]]
// CHECK: tbaa ![[OCPATH]]
// CHECK: store
Vec[0] = Tmp[*Index][0].uh[1];
// CHECK: %uh[[UH2:[0-9]*]] = bitcast %union.vect32
// CHECK: %arrayidx[[AX2:[0-9]*]] = getelementptr{{.*}}%uh[[UH2]]
// CHECK: load i16, i16* %arrayidx[[AX2]]
// CHECK: tbaa [[TAG_vect32_union_member]]
// CHECK: tbaa ![[OCPATH]]
// CHECK: store
Vec[1] = Tmp[*Index][1].uh[1];
bar(Tmp);
}
// CHECK-DAG: [[TAG_vect32_union_member]] = !{[[TYPE_vect32:!.*]], [[TYPE_union_member:!.*]], i64 0}
// CHECK-DAG: [[TYPE_vect32]] = !{!"", [[TYPE_union_member]], i64 0}
// CHECK-DAG: [[TYPE_union_member]] = !{!"union member", [[TYPE_char:!.*]], i64 0}
// CHECK-DAG: [[TYPE_char]] = !{!"omnipotent char", {{.*}}}
// CHECK-DAG: ![[CHAR:[0-9]+]] = !{!"omnipotent char"
// CHECK-DAG: ![[OCPATH]] = !{![[CHAR]], ![[CHAR]], i64 0}