[PATCH] [Patch] UBsan: Type-based blacklisting

[Byoungyoung Lee]

Hi samsonov, rsmith, kcc,

This is a Clang side patch for type-based blacklisting in Ubsan. As this patch is depending on llvm-side patch, please see http://reviews.llvm.org/D4406 for more details. 

Although the diff looks more complicated than it has to be, this patch only adds a simple branch  ---- if (!CGM.getSanitizerBlacklist().isIn(Out.str())).

http://reviews.llvm.org/D4407

Files:
  lib/CodeGen/CGExpr.cpp

Index: lib/CodeGen/CGExpr.cpp
===================================================================
--- lib/CodeGen/CGExpr.cpp
+++ lib/CodeGen/CGExpr.cpp
@@ -539,44 +539,47 @@
     llvm::raw_svector_ostream Out(MangledName);
     CGM.getCXXABI().getMangleContext().mangleCXXRTTI(Ty.getUnqualifiedType(),
                                                      Out);
-    llvm::hash_code TypeHash = hash_value(Out.str());
 
-    // Load the vptr, and compute hash_16_bytes(TypeHash, vptr).
-    llvm::Value *Low = llvm::ConstantInt::get(Int64Ty, TypeHash);
-    llvm::Type *VPtrTy = llvm::PointerType::get(IntPtrTy, 0);
-    llvm::Value *VPtrAddr = Builder.CreateBitCast(Address, VPtrTy);
-    llvm::Value *VPtrVal = Builder.CreateLoad(VPtrAddr);
-    llvm::Value *High = Builder.CreateZExt(VPtrVal, Int64Ty);
+    // Blacklist based on the mangled types
+    if (!CGM.getSanitizerBlacklist().isIn(Out.str())) {
+      llvm::hash_code TypeHash = hash_value(Out.str());
 
-    llvm::Value *Hash = emitHash16Bytes(Builder, Low, High);
-    Hash = Builder.CreateTrunc(Hash, IntPtrTy);
+      // Load the vptr, and compute hash_16_bytes(TypeHash, vptr).
+      llvm::Value *Low = llvm::ConstantInt::get(Int64Ty, TypeHash);
+      llvm::Type *VPtrTy = llvm::PointerType::get(IntPtrTy, 0);
+      llvm::Value *VPtrAddr = Builder.CreateBitCast(Address, VPtrTy);
+      llvm::Value *VPtrVal = Builder.CreateLoad(VPtrAddr);
+      llvm::Value *High = Builder.CreateZExt(VPtrVal, Int64Ty);
 
-    // Look the hash up in our cache.
-    const int CacheSize = 128;
-    llvm::Type *HashTable = llvm::ArrayType::get(IntPtrTy, CacheSize);
-    llvm::Value *Cache = CGM.CreateRuntimeVariable(HashTable,
-                                                   "__ubsan_vptr_type_cache");
-    llvm::Value *Slot = Builder.CreateAnd(Hash,
-                                          llvm::ConstantInt::get(IntPtrTy,
-                                                                 CacheSize-1));
-    llvm::Value *Indices[] = { Builder.getInt32(0), Slot };
-    llvm::Value *CacheVal =
-      Builder.CreateLoad(Builder.CreateInBoundsGEP(Cache, Indices));
+      llvm::Value *Hash = emitHash16Bytes(Builder, Low, High);
+      Hash = Builder.CreateTrunc(Hash, IntPtrTy);
 
-    // If the hash isn't in the cache, call a runtime handler to perform the
-    // hard work of checking whether the vptr is for an object of the right
-    // type. This will either fill in the cache and return, or produce a
-    // diagnostic.
-    llvm::Constant *StaticData[] = {
-      EmitCheckSourceLocation(Loc),
-      EmitCheckTypeDescriptor(Ty),
-      CGM.GetAddrOfRTTIDescriptor(Ty.getUnqualifiedType()),
-      llvm::ConstantInt::get(Int8Ty, TCK)
-    };
-    llvm::Value *DynamicData[] = { Address, Hash };
-    EmitCheck(Builder.CreateICmpEQ(CacheVal, Hash),
-              "dynamic_type_cache_miss", StaticData, DynamicData,
-              CRK_AlwaysRecoverable);
+      // Look the hash up in our cache.
+      const int CacheSize = 128;
+      llvm::Type *HashTable = llvm::ArrayType::get(IntPtrTy, CacheSize);
+      llvm::Value *Cache = CGM.CreateRuntimeVariable(HashTable,
+                                                     "__ubsan_vptr_type_cache");
+      llvm::Value *Slot =
+        Builder.CreateAnd(Hash,llvm::ConstantInt::get(IntPtrTy, CacheSize-1));
+      llvm::Value *Indices[] = { Builder.getInt32(0), Slot };
+      llvm::Value *CacheVal =
+        Builder.CreateLoad(Builder.CreateInBoundsGEP(Cache, Indices));
+
+      // If the hash isn't in the cache, call a runtime handler to perform the
+      // hard work of checking whether the vptr is for an object of the right
+      // type. This will either fill in the cache and return, or produce a
+      // diagnostic.
+      llvm::Constant *StaticData[] = {
+        EmitCheckSourceLocation(Loc),
+        EmitCheckTypeDescriptor(Ty),
+        CGM.GetAddrOfRTTIDescriptor(Ty.getUnqualifiedType()),
+        llvm::ConstantInt::get(Int8Ty, TCK)
+      };
+      llvm::Value *DynamicData[] = { Address, Hash };
+      EmitCheck(Builder.CreateICmpEQ(CacheVal, Hash),
+                "dynamic_type_cache_miss", StaticData, DynamicData,
+                CRK_AlwaysRecoverable);
+    }
   }
 
   if (Done) {
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