From dfb74a58c5ffa658da2b695db7dfdd0b4cc51822 Mon Sep 17 00:00:00 2001
From: Kostya Serebryany <kcc@google.com>
Date: Mon, 2 Dec 2013 08:07:15 +0000
Subject: [PATCH] [tsan] fix instrumentation of vector vptr updates
 (https://code.google.com/p/thread-sanitizer/issues/detail?id=43)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196079 91177308-0d34-0410-b5e6-96231b3b80d8
---
 .../Instrumentation/ThreadSanitizer.cpp         | 11 +++++++----
 .../ThreadSanitizer/vptr_update.ll              | 17 +++++++++++++++++
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/lib/Transforms/Instrumentation/ThreadSanitizer.cpp b/lib/Transforms/Instrumentation/ThreadSanitizer.cpp
index 89fb746a5c4..baec1534e00 100644
--- a/lib/Transforms/Instrumentation/ThreadSanitizer.cpp
+++ b/lib/Transforms/Instrumentation/ThreadSanitizer.cpp
@@ -402,13 +402,16 @@ bool ThreadSanitizer::instrumentLoadOrStore(Instruction *I) {
   if (IsWrite && isVtableAccess(I)) {
     DEBUG(dbgs() << "  VPTR : " << *I << "\n");
     Value *StoredValue = cast<StoreInst>(I)->getValueOperand();
-    // StoredValue does not necessary have a pointer type.
-    if (isa<IntegerType>(StoredValue->getType()))
-      StoredValue = IRB.CreateIntToPtr(StoredValue, IRB.getInt8PtrTy());
+    // StoredValue may be a vector type if we are storing several vptrs at once.
+    // In this case, just take the first element of the vector since this is
+    // enough to find vptr races.
+    if (isa<VectorType>(StoredValue->getType()))
+      StoredValue = IRB.CreateExtractElement(
+          StoredValue, ConstantInt::get(IRB.getInt32Ty(), 0));
     // Call TsanVptrUpdate.
     IRB.CreateCall2(TsanVptrUpdate,
                     IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()),
-                    IRB.CreatePointerCast(StoredValue, IRB.getInt8PtrTy()));
+                    IRB.CreateBitCast(StoredValue, IRB.getInt8PtrTy()));
     NumInstrumentedVtableWrites++;
     return true;
   }
diff --git a/test/Instrumentation/ThreadSanitizer/vptr_update.ll b/test/Instrumentation/ThreadSanitizer/vptr_update.ll
index 95c7bb0e591..46650040540 100644
--- a/test/Instrumentation/ThreadSanitizer/vptr_update.ll
+++ b/test/Instrumentation/ThreadSanitizer/vptr_update.ll
@@ -4,10 +4,27 @@ target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f3
 
 define void @Foo(i8** nocapture %a, i8* %b) nounwind uwtable sanitize_thread {
 entry:
+; CHECK-LABEL: @Foo
 ; CHECK: call void @__tsan_vptr_update
+; CHECK: ret void
   store i8* %b, i8** %a, align 8, !tbaa !0
   ret void
 }
+
+declare i32 @Func1()
+declare i32 @Func2()
+
+; Test that we properly handle vector stores marked as vtable updates.
+define void @VectorVptrUpdate(<2 x i8*>* nocapture %a, i8* %b) nounwind uwtable sanitize_thread {
+entry:
+; CHECK-LABEL: @VectorVptrUpdate
+; CHECK: call void @__tsan_vptr_update{{.*}}Func1
+; CHECK-NOT: call void @__tsan_vptr_update
+; CHECK: ret void
+  store <2 x i8 *> <i8* bitcast(i32 ()* @Func1 to i8 *), i8* bitcast(i32 ()* @Func2 to i8 *)>,  <2 x i8 *>* %a, align 8, !tbaa !0
+  ret void
+}
+
 !0 = metadata !{metadata !2, metadata !2, i64 0}
 !1 = metadata !{metadata !"Simple C/C++ TBAA", null}
 !2 = metadata !{metadata !"vtable pointer", metadata !1}