This revision was automatically updated to reflect the committed changes.
Closed by commit rL319413: [CodeGen] Add initial support for union members in
TBAA (authored by kosarev).
Changed prior to commit:
https://reviews.llvm.org/D39455?vs=124726&id=124883#toc
Repository:
rL LLVM
https://reviews.llvm.org/D39455
Files:
cfe/trunk/lib/CodeGen/CGExpr.cpp
cfe/trunk/lib/CodeGen/CodeGenModule.h
cfe/trunk/lib/CodeGen/CodeGenTBAA.cpp
cfe/trunk/lib/CodeGen/CodeGenTBAA.h
cfe/trunk/test/CodeGen/tbaa-union.cpp
cfe/trunk/test/CodeGen/union-tbaa1.c
Index: cfe/trunk/test/CodeGen/tbaa-union.cpp
===================================================================
--- cfe/trunk/test/CodeGen/tbaa-union.cpp
+++ cfe/trunk/test/CodeGen/tbaa-union.cpp
@@ -0,0 +1,100 @@
+// 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}
Index: cfe/trunk/test/CodeGen/union-tbaa1.c
===================================================================
--- cfe/trunk/test/CodeGen/union-tbaa1.c
+++ cfe/trunk/test/CodeGen/union-tbaa1.c
@@ -15,30 +15,32 @@
// But no tbaa for the two stores:
// CHECK: %uw[[UW1:[0-9]*]] = getelementptr
// CHECK: store{{.*}}%uw[[UW1]]
-// CHECK: tbaa ![[OCPATH:[0-9]+]]
+// CHECK: tbaa [[TAG_vect32_union_member:![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 ![[OCPATH]]
+// CHECK: tbaa [[TAG_vect32_union_member]]
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 ![[OCPATH]]
+// CHECK: tbaa [[TAG_vect32_union_member]]
// 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 ![[OCPATH]]
+// CHECK: tbaa [[TAG_vect32_union_member]]
// CHECK: store
Vec[1] = Tmp[*Index][1].uh[1];
bar(Tmp);
}
-// CHECK-DAG: ![[CHAR:[0-9]+]] = !{!"omnipotent char"
-// CHECK-DAG: ![[OCPATH]] = !{![[CHAR]], ![[CHAR]], i64 0}
+// 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", {{.*}}}
Index: cfe/trunk/lib/CodeGen/CGExpr.cpp
===================================================================
--- cfe/trunk/lib/CodeGen/CGExpr.cpp
+++ cfe/trunk/lib/CodeGen/CGExpr.cpp
@@ -3723,9 +3723,6 @@
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.
@@ -3736,16 +3733,26 @@
"Nonzero offset for an access with no base type!");
}
- // 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;
+ // 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);
+
+ // 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();
Index: cfe/trunk/lib/CodeGen/CodeGenTBAA.cpp
===================================================================
--- cfe/trunk/lib/CodeGen/CodeGenTBAA.cpp
+++ cfe/trunk/lib/CodeGen/CodeGenTBAA.cpp
@@ -74,6 +74,10 @@
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))
@@ -101,9 +105,8 @@
return false;
if (RD->hasFlexibleArrayMember())
return false;
- // RD can be struct, union, class, interface or enum.
- // For now, we only handle struct and class.
- if (RD->isStruct() || RD->isClass())
+ // For now, we do not allow interface classes to be base access types.
+ if (RD->isStruct() || RD->isClass() || RD->isUnion())
return true;
}
return false;
@@ -277,18 +280,27 @@
const RecordDecl *RD = TTy->getDecl()->getDefinition();
const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
SmallVector<llvm::MDBuilder::TBAAStructField, 4> Fields;
- 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,
+ 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;
+
+ 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;
@@ -333,6 +345,8 @@
if (Info.isMayAlias())
Info = TBAAAccessInfo(getChar(), Info.Size);
+ else if (Info.isUnionMember())
+ Info.AccessType = getUnionMemberType(Info.Size);
if (!Info.AccessType)
return nullptr;
Index: cfe/trunk/lib/CodeGen/CodeGenModule.h
===================================================================
--- cfe/trunk/lib/CodeGen/CodeGenModule.h
+++ cfe/trunk/lib/CodeGen/CodeGenModule.h
@@ -688,8 +688,9 @@
/// getTBAAInfoForSubobject - Get TBAA information for an access with a given
/// base lvalue.
TBAAAccessInfo getTBAAInfoForSubobject(LValue Base, QualType AccessType) {
- if (Base.getTBAAInfo().isMayAlias())
- return TBAAAccessInfo::getMayAliasInfo();
+ TBAAAccessInfo TBAAInfo = Base.getTBAAInfo();
+ if (TBAAInfo.isMayAlias() || TBAAInfo.isUnionMember())
+ return TBAAInfo;
return getTBAAAccessInfo(AccessType);
}
Index: cfe/trunk/lib/CodeGen/CodeGenTBAA.h
===================================================================
--- cfe/trunk/lib/CodeGen/CodeGenTBAA.h
+++ cfe/trunk/lib/CodeGen/CodeGenTBAA.h
@@ -34,9 +34,10 @@
// TBAAAccessKind - A kind of TBAA memory access descriptor.
enum class TBAAAccessKind : unsigned {
- Ordinary,
- MayAlias,
- Incomplete,
+ 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.
};
// TBAAAccessInfo - Describes a memory access in terms of TBAA.
@@ -77,6 +78,14 @@
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 &&
@@ -148,6 +157,10 @@
/// 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,
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