TBAA: add isTBAAVtableAccess to MDNode so clients can call the function

instead of having its own implementation.

The implementation of isTBAAVtableAccess is in TypeBasedAliasAnalysis.cpp
since it is related to the format of TBAA metadata.

The path for struct-path tbaa will be exercised by
test/Instrumentation/ThreadSanitizer/read_from_global.ll, vptr_read.ll, and
vptr_update.ll when struct-path tbaa is on by default.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190216 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 24 insertions, 6 deletions

diff --git a/include/llvm/IR/Metadata.h b/include/llvm/IR/Metadata.h
index acd84d7..49eb895 100644
--- a/include/llvm/IR/Metadata.h
+++ b/include/llvm/IR/Metadata.h
@@ -161,6 +161,9 @@ public:
     return V->getValueID() == MDNodeVal;
   }
 
+  /// Check whether MDNode is a vtable access.
+  bool isTBAAVtableAccess() const;
+
   /// Methods for metadata merging.
   static MDNode *getMostGenericTBAA(MDNode *A, MDNode *B);
   static MDNode *getMostGenericFPMath(MDNode *A, MDNode *B);
diff --git a/lib/Analysis/TypeBasedAliasAnalysis.cpp b/lib/Analysis/TypeBasedAliasAnalysis.cpp
index bbf3c3a..ac3965f 100644
--- a/lib/Analysis/TypeBasedAliasAnalysis.cpp
+++ b/lib/Analysis/TypeBasedAliasAnalysis.cpp
@@ -458,6 +458,25 @@ TypeBasedAliasAnalysis::getModRefInfo(ImmutableCallSite CS1,
   return AliasAnalysis::getModRefInfo(CS1, CS2);
 }
 
+bool MDNode::isTBAAVtableAccess() const {
+  if (!EnableStructPathTBAA) {
+    if (getNumOperands() < 1) return false;
+    if (MDString *Tag1 = dyn_cast<MDString>(getOperand(0))) {
+      if (Tag1->getString() == "vtable pointer") return true;
+    }
+    return false;
+  }
+
+  // For struct-path aware TBAA, we use the access type of the tag.
+  if (getNumOperands() < 2) return false;
+  MDNode *Tag = cast_or_null<MDNode>(getOperand(1));
+  if (!Tag) return false;
+  if (MDString *Tag1 = dyn_cast<MDString>(Tag->getOperand(0))) {
+    if (Tag1->getString() == "vtable pointer") return true;
+  }
+  return false;  
+}
+
 MDNode *MDNode::getMostGenericTBAA(MDNode *A, MDNode *B) {
   if (!A || !B)
     return NULL;
diff --git a/lib/Transforms/Instrumentation/ThreadSanitizer.cpp b/lib/Transforms/Instrumentation/ThreadSanitizer.cpp
index e19ceba..2c8a7c4 100644
--- a/lib/Transforms/Instrumentation/ThreadSanitizer.cpp
+++ b/lib/Transforms/Instrumentation/ThreadSanitizer.cpp
@@ -240,12 +240,8 @@ bool ThreadSanitizer::doInitialization(Module &M) {
 }
 
 static bool isVtableAccess(Instruction *I) {
-  if (MDNode *Tag = I->getMetadata(LLVMContext::MD_tbaa)) {
-    if (Tag->getNumOperands() < 1) return false;
-    if (MDString *Tag1 = dyn_cast<MDString>(Tag->getOperand(0))) {
-      if (Tag1->getString() == "vtable pointer") return true;
-    }
-  }
+  if (MDNode *Tag = I->getMetadata(LLVMContext::MD_tbaa))
+    return Tag->isTBAAVtableAccess();
   return false;
 }