TBAA: make sure zero-length bitfield works for tbaa.struct and path-aware tbaa

For ms structs, zero-length bitfields following non-bitfield members are
completely ignored, we should not increase the field index.
Before the fix, we will have an assertion failure.

llvm-svn: 180038

1 files changed, 24 insertions, 1 deletions

diff --git a/clang/lib/CodeGen/CodeGenTBAA.cpp b/clang/lib/CodeGen/CodeGenTBAA.cpp
index bb1ebda9084..95b9714c348 100644
--- a/clang/lib/CodeGen/CodeGenTBAA.cpp
+++ b/clang/lib/CodeGen/CodeGenTBAA.cpp
@@ -204,8 +204,18 @@ CodeGenTBAA::CollectFields(uint64_t BaseOffset,
     const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
 
     unsigned idx = 0;
+    const FieldDecl *LastFD = 0;
+    bool IsMsStruct = RD->isMsStruct(Context);
     for (RecordDecl::field_iterator i = RD->field_begin(),
          e = RD->field_end(); i != e; ++i, ++idx) {
+      if (IsMsStruct) {
+        // Zero-length bitfields following non-bitfield members are ignored.
+        if (Context.ZeroBitfieldFollowsNonBitfield(*i, LastFD)) {
+          --idx;
+          continue;
+        }
+        LastFD = *i;
+      }
       uint64_t Offset = BaseOffset +
                         Layout.getFieldOffset(idx) / Context.getCharWidth();
       QualType FieldQTy = i->getType();
@@ -220,7 +230,9 @@ CodeGenTBAA::CollectFields(uint64_t BaseOffset,
   uint64_t Offset = BaseOffset;
   uint64_t Size = Context.getTypeSizeInChars(QTy).getQuantity();
   llvm::MDNode *TBAAInfo = MayAlias ? getChar() : getTBAAInfo(QTy);
-  Fields.push_back(llvm::MDBuilder::TBAAStructField(Offset, Size, TBAAInfo));
+  llvm::MDNode *TBAATag = CodeGenOpts.StructPathTBAA ?
+                          getTBAAScalarTagInfo(TBAAInfo) : TBAAInfo;
+  Fields.push_back(llvm::MDBuilder::TBAAStructField(Offset, Size, TBAATag));
   return true;
 }
 
@@ -265,8 +277,19 @@ CodeGenTBAA::getTBAAStructTypeInfo(QualType QTy) {
     const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
     SmallVector <std::pair<uint64_t, llvm::MDNode*>, 4> Fields;
     unsigned idx = 0;
+    const FieldDecl *LastFD = 0;
+    bool IsMsStruct = RD->isMsStruct(Context);
     for (RecordDecl::field_iterator i = RD->field_begin(),
          e = RD->field_end(); i != e; ++i, ++idx) {
+      if (IsMsStruct) {
+        // Zero-length bitfields following non-bitfield members are ignored.
+        if (Context.ZeroBitfieldFollowsNonBitfield(*i, LastFD)) {
+          --idx;
+          continue;
+        }
+        LastFD = *i;
+      }
+
       QualType FieldQTy = i->getType();
       llvm::MDNode *FieldNode;
       if (isTBAAPathStruct(FieldQTy))