[TBAA] Handle bitfields when generating !tbaa.struct metadata.

clang/lib/CodeGen/CodeGenModule.cpp

@@ -397,7 +397,7 @@ CodeGenModule::CodeGenModule(ASTContext &C,
   // Enable TBAA unless it's suppressed. ThreadSanitizer needs TBAA even at O0.
   if (LangOpts.Sanitize.has(SanitizerKind::Thread) ||
       (!CodeGenOpts.RelaxedAliasing && CodeGenOpts.OptimizationLevel > 0))
-    TBAA.reset(new CodeGenTBAA(Context, TheModule, CodeGenOpts, getLangOpts(),
+    TBAA.reset(new CodeGenTBAA(Context, getTypes(), TheModule, CodeGenOpts, getLangOpts(),
                                getCXXABI().getMangleContext()));
 
   // If debug info or coverage generation is enabled, create the CGDebugInfo

clang/lib/CodeGen/CodeGenTBAA.cpp

@@ -15,6 +15,8 @@
 //===----------------------------------------------------------------------===//
 
 #include "CodeGenTBAA.h"
+#include "CGRecordLayout.h"
+#include "CodeGenTypes.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/Attr.h"
 #include "clang/AST/Mangle.h"
@@ -26,13 +28,14 @@
 #include "llvm/IR/Metadata.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/Type.h"
+#include "llvm/Support/Debug.h"
 using namespace clang;
 using namespace CodeGen;
 
-CodeGenTBAA::CodeGenTBAA(ASTContext &Ctx, llvm::Module &M,
+CodeGenTBAA::CodeGenTBAA(ASTContext &Ctx, CodeGenTypes &CGTypes, llvm::Module &M,
                          const CodeGenOptions &CGO,
                          const LangOptions &Features, MangleContext &MContext)
-  : Context(Ctx), Module(M), CodeGenOpts(CGO),
+  : Context(Ctx), CGTypes(CGTypes), Module(M), CodeGenOpts(CGO),
     Features(Features), MContext(MContext), MDHelper(M.getContext()),
     Root(nullptr), Char(nullptr)
 {}
@@ -294,18 +297,49 @@ CodeGenTBAA::CollectFields(uint64_t BaseOffset,
         return false;
 
     const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
+    const CGRecordLayout &CGRL = CGTypes.getCGRecordLayout(RD);
 
     unsigned idx = 0;
-    for (RecordDecl::field_iterator i = RD->field_begin(),
-         e = RD->field_end(); i != e; ++i, ++idx) {
-      if ((*i)->isZeroSize(Context) || (*i)->isUnnamedBitfield())
+    for (RecordDecl::field_iterator i = RD->field_begin(), e = RD->field_end();
+         i != e;) {
+      if ((*i)->isZeroSize(Context)) {
+        ++i;
+        ++idx;
         continue;
-      uint64_t Offset = BaseOffset +
-                        Layout.getFieldOffset(idx) / Context.getCharWidth();
+      }
+
+      uint64_t Offset =
+          BaseOffset + Layout.getFieldOffset(idx) / Context.getCharWidth();
       QualType FieldQTy = i->getType();
+      // Create a single field for consecutive named bitfields using char as
+      // base type.
+      if ((*i)->isBitField() && !(*i)->isUnnamedBitfield()) {
+        unsigned CurrentBitFieldSize = 0;
+        unsigned CurrentBitFieldOffset = CGRL.getBitFieldInfo(*i).Offset;
+        while (i != e && (*i)->isBitField() && !(*i)->isUnnamedBitfield()) {
+          const CGBitFieldInfo &Info = CGRL.getBitFieldInfo(*i);
+          if (CurrentBitFieldSize + CurrentBitFieldOffset != Info.Offset)
+            break;
+          CurrentBitFieldSize += Info.Size;
+          CurrentBitFieldOffset = Info.Offset;
+          ++i;
+          ++idx;
+        }
+        uint64_t Size =
+            llvm::divideCeil(CurrentBitFieldSize, Context.getCharWidth());
+        llvm::MDNode *TBAAType = getChar();
+        llvm::MDNode *TBAATag =
+            getAccessTagInfo(TBAAAccessInfo(TBAAType, Size));
+        Fields.push_back(
+            llvm::MDBuilder::TBAAStructField(Offset, Size, TBAATag));
+        continue;
+      }
       if (!CollectFields(Offset, FieldQTy, Fields,
                          MayAlias || TypeHasMayAlias(FieldQTy)))
         return false;
+
+      ++i;
+      ++idx;
     }
     return true;
   }

clang/lib/CodeGen/CodeGenTBAA.h

@@ -29,6 +29,7 @@ namespace clang {
   class Type;
 
 namespace CodeGen {
+  class CodeGenTypes;
 
 // TBAAAccessKind - A kind of TBAA memory access descriptor.
 enum class TBAAAccessKind : unsigned {
@@ -115,6 +116,7 @@ struct TBAAAccessInfo {
 /// while lowering AST types to LLVM types.
 class CodeGenTBAA {
   ASTContext &Context;
+  CodeGenTypes &CGTypes;
   llvm::Module &Module;
   const CodeGenOptions &CodeGenOpts;
   const LangOptions &Features;
@@ -167,7 +169,7 @@ class CodeGenTBAA {
   llvm::MDNode *getBaseTypeInfoHelper(const Type *Ty);
 
 public:
-  CodeGenTBAA(ASTContext &Ctx, llvm::Module &M, const CodeGenOptions &CGO,
+  CodeGenTBAA(ASTContext &Ctx, CodeGenTypes &CGTypes, llvm::Module &M, const CodeGenOptions &CGO,
               const LangOptions &Features, MangleContext &MContext);
   ~CodeGenTBAA();
 

clang/test/CodeGen/tbaa-struct.cpp

@@ -145,10 +145,10 @@ void copy9(NamedBitfields2 *a1, NamedBitfields2 *a2) {
 // CHECK-OLD: [[TS3]] = !{i64 0, i64 8, !{{.*}}, i64 0, i64 2, !{{.*}}, i64 4, i64 8, !{{.*}}}
 // CHECK-OLD: [[TS4]] = !{i64 0, i64 1, [[TAG_CHAR]], i64 1, i64 1, [[TAG_CHAR]], i64 2, i64 1, [[TAG_CHAR]]}
 // CHECK-OLD: [[TS5]] = !{i64 0, i64 1, [[TAG_CHAR]], i64 4, i64 1, [[TAG_CHAR]], i64 5, i64 1, [[TAG_CHAR]]}
-// CHECK-OLD: [[TS6]] = !{i64 0, i64 4, [[TAG_INT]], i64 1, i64 4, [[TAG_INT]], i64 2, i64 1, [[TAG_CHAR]], i64 8, i64 8, [[TAG_DOUBLE:!.+]]}
+// CHECK-OLD: [[TS6]] = !{i64 0, i64 2, [[TAG_CHAR]], i64 2, i64 1, [[TAG_CHAR]], i64 8, i64 8, [[TAG_DOUBLE:!.+]]}
 // CHECK-OLD: [[TAG_DOUBLE]] = !{[[DOUBLE:!.+]], [[DOUBLE]], i64 0}
 // CHECK-OLD  [[DOUBLE]] = !{!"double", [[CHAR]], i64 0}
-// CHECK-OLD: [[TS7]] = !{i64 0, i64 1, [[TAG_CHAR]], i64 1, i64 1, [[TAG_CHAR]], i64 2, i64 1, [[TAG_CHAR]], i64 3, i64 4, [[TAG_INT]], i64 3, i64 4, [[TAG_INT]], i64 4, i64 1, [[TAG_CHAR]], i64 8, i64 8, [[TAG_DOUBLE]], i64 16, i64 4, [[TAG_INT]]}
+// CHECK-OLD: [[TS7]] = !{i64 0, i64 1, [[TAG_CHAR]], i64 1, i64 1, [[TAG_CHAR]], i64 2, i64 1, [[TAG_CHAR]], i64 3, i64 1, [[TAG_CHAR]], i64 4, i64 1, [[TAG_CHAR]], i64 8, i64 8, [[TAG_DOUBLE]], i64 16, i64 1, [[TAG_CHAR]]}
 
 // CHECK-NEW-DAG: [[TYPE_char:!.*]] = !{{{.*}}, i64 1, !"omnipotent char"}
 // CHECK-NEW-DAG: [[TAG_char]] = !{[[TYPE_char]], [[TYPE_char]], i64 0, i64 0}