Initial support for struct-path aware TBAA.
Added TBAABaseType and TBAAOffset in LValue. These two fields are initialized to
the actual type and 0, and are updated in EmitLValueForField.
Path-aware TBAA tags are enabled for EmitLoadOfScalar and EmitStoreOfScalar.
Added command line option -struct-path-tbaa.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@178797 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CodeGenTBAA.cpp b/lib/CodeGen/CodeGenTBAA.cpp
index cfa141e..7e4d34a 100644
--- a/lib/CodeGen/CodeGenTBAA.cpp
+++ b/lib/CodeGen/CodeGenTBAA.cpp
@@ -21,6 +21,7 @@
#include "clang/AST/Mangle.h"
#include "clang/AST/RecordLayout.h"
#include "clang/Frontend/CodeGenOptions.h"
+#include "llvm/ADT/SmallSet.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Metadata.h"
@@ -225,3 +226,87 @@
// For now, handle any other kind of type conservatively.
return StructMetadataCache[Ty] = NULL;
}
+
+/// Check if the given type can be handled by path-aware TBAA.
+static bool isTBAAPathStruct(QualType QTy) {
+ if (const RecordType *TTy = QTy->getAs<RecordType>()) {
+ const RecordDecl *RD = TTy->getDecl()->getDefinition();
+ // RD can be struct, union, class, interface or enum.
+ // For now, we only handle struct.
+ if (RD->isStruct() && !RD->hasFlexibleArrayMember())
+ return true;
+ }
+ return false;
+}
+
+llvm::MDNode *
+CodeGenTBAA::getTBAAStructTypeInfo(QualType QTy) {
+ const Type *Ty = Context.getCanonicalType(QTy).getTypePtr();
+ assert(isTBAAPathStruct(QTy));
+
+ if (llvm::MDNode *N = StructTypeMetadataCache[Ty])
+ return N;
+
+ if (const RecordType *TTy = QTy->getAs<RecordType>()) {
+ const RecordDecl *RD = TTy->getDecl()->getDefinition();
+
+ const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
+ SmallVector <std::pair<uint64_t, llvm::MDNode*>, 4> Fields;
+ // To reduce the size of MDNode for a given struct type, we only output
+ // once for all the fields with the same scalar types.
+ // Offsets for scalar fields in the type DAG are not used.
+ llvm::SmallSet <llvm::MDNode*, 4> ScalarFieldTypes;
+ unsigned idx = 0;
+ for (RecordDecl::field_iterator i = RD->field_begin(),
+ e = RD->field_end(); i != e; ++i, ++idx) {
+ QualType FieldQTy = i->getType();
+ llvm::MDNode *FieldNode;
+ if (isTBAAPathStruct(FieldQTy))
+ FieldNode = getTBAAStructTypeInfo(FieldQTy);
+ else {
+ FieldNode = getTBAAInfo(FieldQTy);
+ // Ignore this field if the type already exists.
+ if (ScalarFieldTypes.count(FieldNode))
+ continue;
+ ScalarFieldTypes.insert(FieldNode);
+ }
+ if (!FieldNode)
+ return StructTypeMetadataCache[Ty] = NULL;
+ Fields.push_back(std::make_pair(
+ Layout.getFieldOffset(idx) / Context.getCharWidth(), FieldNode));
+ }
+
+ // TODO: This is using the RTTI name. Is there a better way to get
+ // a unique string for a type?
+ SmallString<256> OutName;
+ llvm::raw_svector_ostream Out(OutName);
+ MContext.mangleCXXRTTIName(QualType(Ty, 0), Out);
+ Out.flush();
+ // Create the struct type node with a vector of pairs (offset, type).
+ return StructTypeMetadataCache[Ty] =
+ MDHelper.createTBAAStructTypeNode(OutName, Fields);
+ }
+
+ return StructMetadataCache[Ty] = NULL;
+}
+
+llvm::MDNode *
+CodeGenTBAA::getTBAAStructTagInfo(QualType BaseQTy, llvm::MDNode *AccessNode,
+ uint64_t Offset) {
+ if (!CodeGenOpts.StructPathTBAA)
+ return AccessNode;
+
+ const Type *BTy = Context.getCanonicalType(BaseQTy).getTypePtr();
+ TBAAPathTag PathTag = TBAAPathTag(BTy, AccessNode, Offset);
+ if (llvm::MDNode *N = StructTagMetadataCache[PathTag])
+ return N;
+
+ llvm::MDNode *BNode = 0;
+ if (isTBAAPathStruct(BaseQTy))
+ BNode = getTBAAStructTypeInfo(BaseQTy);
+ if (!BNode)
+ return StructTagMetadataCache[PathTag] = AccessNode;
+
+ return StructTagMetadataCache[PathTag] =
+ MDHelper.createTBAAStructTagNode(BNode, AccessNode, Offset);
+}