[msan] Origin tracking with history.

LLVM part of MSan implementation of advanced origin tracking,
when we record not only creation point, but all locations where
an uninitialized value was stored to memory, too.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204151 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 20 insertions, 10 deletions

diff --git a/lib/Transforms/Instrumentation/MemorySanitizer.cpp b/lib/Transforms/Instrumentation/MemorySanitizer.cpp
index 99114d1414..c07892229d 100644
--- a/lib/Transforms/Instrumentation/MemorySanitizer.cpp
+++ b/lib/Transforms/Instrumentation/MemorySanitizer.cpp
@@ -133,9 +133,9 @@ static const unsigned kShadowTLSAlignment = 8;
 ///
 /// Adds a section to MemorySanitizer report that points to the allocation
 /// (stack or heap) the uninitialized bits came from originally.
-static cl::opt<bool> ClTrackOrigins("msan-track-origins",
+static cl::opt<int> ClTrackOrigins("msan-track-origins",
        cl::desc("Track origins (allocation sites) of poisoned memory"),
-       cl::Hidden, cl::init(false));
+       cl::Hidden, cl::init(0));
 static cl::opt<bool> ClKeepGoing("msan-keep-going",
        cl::desc("keep going after reporting a UMR"),
        cl::Hidden, cl::init(false));
@@ -199,10 +199,10 @@ namespace {
 /// uninitialized reads.
 class MemorySanitizer : public FunctionPass {
  public:
-  MemorySanitizer(bool TrackOrigins = false,
+  MemorySanitizer(int TrackOrigins = 0,
                   StringRef BlacklistFile = StringRef())
       : FunctionPass(ID),
-        TrackOrigins(TrackOrigins || ClTrackOrigins),
+        TrackOrigins(std::max(TrackOrigins, (int)ClTrackOrigins)),
         DL(0),
         WarningFn(0),
         BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile : BlacklistFile),
@@ -216,7 +216,7 @@ class MemorySanitizer : public FunctionPass {
   void initializeCallbacks(Module &M);
 
   /// \brief Track origins (allocation points) of uninitialized values.
-  bool TrackOrigins;
+  int TrackOrigins;
 
   const DataLayout *DL;
   LLVMContext *C;
@@ -250,6 +250,9 @@ class MemorySanitizer : public FunctionPass {
   Value *MsanSetAllocaOrigin4Fn;
   /// \brief Run-time helper that poisons stack on function entry.
   Value *MsanPoisonStackFn;
+  /// \brief Run-time helper that records a store (or any event) of an
+  /// uninitialized value and returns an updated origin id encoding this info.
+  Value *MsanChainOriginFn;
   /// \brief MSan runtime replacements for memmove, memcpy and memset.
   Value *MemmoveFn, *MemcpyFn, *MemsetFn;
 
@@ -286,7 +289,7 @@ INITIALIZE_PASS(MemorySanitizer, "msan",
                 "MemorySanitizer: detects uninitialized reads.",
                 false, false)
 
-FunctionPass *llvm::createMemorySanitizerPass(bool TrackOrigins,
+FunctionPass *llvm::createMemorySanitizerPass(int TrackOrigins,
                                               StringRef BlacklistFile) {
   return new MemorySanitizer(TrackOrigins, BlacklistFile);
 }
@@ -323,6 +326,8 @@ void MemorySanitizer::initializeCallbacks(Module &M) {
     IRB.getInt8PtrTy(), IntptrTy, NULL);
   MsanPoisonStackFn = M.getOrInsertFunction(
     "__msan_poison_stack", IRB.getVoidTy(), IRB.getInt8PtrTy(), IntptrTy, NULL);
+  MsanChainOriginFn = M.getOrInsertFunction(
+    "__msan_chain_origin", IRB.getInt32Ty(), IRB.getInt32Ty(), NULL);
   MemmoveFn = M.getOrInsertFunction(
     "__msan_memmove", IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
     IRB.getInt8PtrTy(), IntptrTy, NULL);
@@ -520,6 +525,11 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
                  << F.getName() << "'\n");
   }
 
+  Value *updateOrigin(Value *V, IRBuilder<> &IRB) {
+    if (MS.TrackOrigins <= 1) return V;
+    return IRB.CreateCall(MS.MsanChainOriginFn, V);
+  }
+
   void materializeStores() {
     for (size_t i = 0, n = StoreList.size(); i < n; i++) {
       StoreInst& I = *dyn_cast<StoreInst>(StoreList[i]);
@@ -544,8 +554,8 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
       if (MS.TrackOrigins) {
         unsigned Alignment = std::max(kMinOriginAlignment, I.getAlignment());
         if (isa<StructType>(Shadow->getType())) {
-          IRB.CreateAlignedStore(getOrigin(Val), getOriginPtr(Addr, IRB),
-                                 Alignment);
+          IRB.CreateAlignedStore(updateOrigin(getOrigin(Val), IRB),
+                                 getOriginPtr(Addr, IRB), Alignment);
         } else {
           Value *ConvertedShadow = convertToShadowTyNoVec(Shadow, IRB);
 
@@ -560,8 +570,8 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
           Instruction *CheckTerm =
               SplitBlockAndInsertIfThen(Cmp, &I, false, MS.OriginStoreWeights);
           IRBuilder<> IRBNew(CheckTerm);
-          IRBNew.CreateAlignedStore(getOrigin(Val), getOriginPtr(Addr, IRBNew),
-                                    Alignment);
+          IRBNew.CreateAlignedStore(updateOrigin(getOrigin(Val), IRBNew),
+                                    getOriginPtr(Addr, IRBNew), Alignment);
         }
       }
     }