[UBsan] Skip -fsanitize=vptr instrumentations when the pointer value is null.

Otherwise -fsanitize=vptr causes the program to crash when it downcasts
a null pointer.

Reviewed in http://reviews.llvm.org/D4412.
Patch by Byoungyoung Lee!

llvm-svn: 213393

diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index b08af94..512b323 100644 (file)
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -463,7 +463,7 @@ void CodeGenFunction::EmitTypeCheck(TypeCheckKind TCK, SourceLocation Loc,
   llvm::Value *Cond = nullptr;
   llvm::BasicBlock *Done = nullptr;
 
-  if (SanOpts->Null) {
+  if (SanOpts->Null || TCK == TCK_DowncastPointer) {
     // The glvalue must not be an empty glvalue.
     Cond = Builder.CreateICmpNE(
         Address, llvm::Constant::getNullValue(Address->getType()));

diff --git a/clang/test/CodeGenCXX/catch-undef-behavior.cpp b/clang/test/CodeGenCXX/catch-undef-behavior.cpp
index f875d92..333855d 100644 (file)
--- a/clang/test/CodeGenCXX/catch-undef-behavior.cpp
+++ b/clang/test/CodeGenCXX/catch-undef-behavior.cpp
@@ -1,5 +1,6 @@
 // RUN: %clang_cc1 -std=c++11 -fsanitize=signed-integer-overflow,integer-divide-by-zero,float-divide-by-zero,shift,unreachable,return,vla-bound,alignment,null,vptr,object-size,float-cast-overflow,bool,enum,array-bounds,function -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s
 // RUN: %clang_cc1 -std=c++11 -fsanitize=vptr,address -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s --check-prefix=CHECK-ASAN
+// RUN: %clang_cc1 -std=c++11 -fsanitize=vptr -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s --check-prefix=DOWNCAST-NULL
 
 struct S {
   double d;
@@ -190,10 +191,15 @@ int bad_enum_value() {
 }
 
 // CHECK-LABEL: @_Z20bad_downcast_pointer
+// DOWNCAST-NULL-LABEL: @_Z20bad_downcast_pointer
 void bad_downcast_pointer(S *p) {
   // CHECK: %[[NONNULL:.*]] = icmp ne {{.*}}, null
   // CHECK: br i1 %[[NONNULL]],
 
+  // A null poiner access is guarded without -fsanitize=null.
+  // DOWNCAST-NULL: %[[NONNULL:.*]] = icmp ne {{.*}}, null
+  // DOWNCAST-NULL: br i1 %[[NONNULL]],
+
   // CHECK: %[[SIZE:.*]] = call i64 @llvm.objectsize.i64.p0i8(
   // CHECK: %[[E1:.*]] = icmp uge i64 %[[SIZE]], 24
   // CHECK: %[[MISALIGN:.*]] = and i64 %{{.*}}, 7