[ubsan] Have -fsanitize=vptr emit a null check if -fsanitize=null isn't available
In r309007, I made -fsanitize=null a hard prerequisite for -fsanitize=vptr. I
did not see the need for the two checks to have separate null checking logic
for the same pointer. I expected the two checks to either always be enabled
together, or to be mutually compatible.
In the mailing list discussion re: r309007 it became clear that that isn't the
case. If a codebase is -fsanitize=vptr clean but not -fsanitize=null clean,
it's useful to have -fsanitize=vptr emit its own null check. That's what this
patch does: with it, -fsanitize=vptr can be used without -fsanitize=null.
Differential Revision: https://reviews.llvm.org/D36112
llvm-svn: 309846
diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index e9ad05c..ec48b2c 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -694,17 +694,17 @@
// -- the [pointer or glvalue] is used to access a non-static data member
// or call a non-static member function
CXXRecordDecl *RD = Ty->getAsCXXRecordDecl();
- bool HasNullCheck = IsGuaranteedNonNull || IsNonNull;
if (SanOpts.has(SanitizerKind::Vptr) &&
- !SkippedChecks.has(SanitizerKind::Vptr) && HasNullCheck &&
+ !SkippedChecks.has(SanitizerKind::Vptr) &&
(TCK == TCK_MemberAccess || TCK == TCK_MemberCall ||
TCK == TCK_DowncastPointer || TCK == TCK_DowncastReference ||
TCK == TCK_UpcastToVirtualBase) &&
RD && RD->hasDefinition() && RD->isDynamicClass()) {
// Ensure that the pointer is non-null before loading it. If there is no
- // compile-time guarantee, reuse the run-time null check.
+ // compile-time guarantee, reuse the run-time null check or emit a new one.
if (!IsGuaranteedNonNull) {
- assert(IsNonNull && "Missing run-time null check");
+ if (!IsNonNull)
+ IsNonNull = Builder.CreateIsNotNull(Ptr);
if (!Done)
Done = createBasicBlock("vptr.null");
llvm::BasicBlock *VptrNotNull = createBasicBlock("vptr.not.null");