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[ubsan] Add helpers to decide when null/vptr checks are required. NFC. 

llvm-svn: 314750
This commit is contained in:
Vedant Kumar 2017-10-03 01:27:25 +00:00
parent 8a7153312b
commit 24792e3ab1
2 changed files with 21 additions and 8 deletions
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23
clang/lib/CodeGen/CGExpr.cpp
View File

@ -569,6 +569,19 @@ static llvm::Value *emitHash16Bytes(CGBuilderTy &Builder, llvm::Value *Low,
return Builder.CreateMul(B1, KMul);
}
bool CodeGenFunction::isNullPointerAllowed(TypeCheckKind TCK) {
return TCK == TCK_DowncastPointer || TCK == TCK_Upcast ||
TCK == TCK_UpcastToVirtualBase;
}
bool CodeGenFunction::isVptrCheckRequired(TypeCheckKind TCK, QualType Ty) {
CXXRecordDecl *RD = Ty->getAsCXXRecordDecl();
return (RD && RD->hasDefinition() && RD->isDynamicClass()) &&
(TCK == TCK_MemberAccess || TCK == TCK_MemberCall ||
TCK == TCK_DowncastPointer || TCK == TCK_DowncastReference ||
TCK == TCK_UpcastToVirtualBase);
}
bool CodeGenFunction::sanitizePerformTypeCheck() const {
return SanOpts.has(SanitizerKind::Null) |
SanOpts.has(SanitizerKind::Alignment) |
@ -608,8 +621,7 @@ void CodeGenFunction::EmitTypeCheck(TypeCheckKind TCK, SourceLocation Loc,
llvm::Value *IsNonNull = nullptr;
bool IsGuaranteedNonNull =
SkippedChecks.has(SanitizerKind::Null) || PtrToAlloca;
bool AllowNullPointers = TCK == TCK_DowncastPointer || TCK == TCK_Upcast ||
TCK == TCK_UpcastToVirtualBase;
bool AllowNullPointers = isNullPointerAllowed(TCK);
if ((SanOpts.has(SanitizerKind::Null) || AllowNullPointers) &&
!IsGuaranteedNonNull) {
// The glvalue must not be an empty glvalue.
@ -696,13 +708,8 @@ void CodeGenFunction::EmitTypeCheck(TypeCheckKind TCK, SourceLocation Loc,
// The program has undefined behavior if:
// -- the [pointer or glvalue] is used to access a non-static data member
// or call a non-static member function
CXXRecordDecl *RD = Ty->getAsCXXRecordDecl();
if (SanOpts.has(SanitizerKind::Vptr) &&
!SkippedChecks.has(SanitizerKind::Vptr) &&
(TCK == TCK_MemberAccess || TCK == TCK_MemberCall ||
TCK == TCK_DowncastPointer || TCK == TCK_DowncastReference ||
TCK == TCK_UpcastToVirtualBase) &&
RD && RD->hasDefinition() && RD->isDynamicClass()) {
!SkippedChecks.has(SanitizerKind::Vptr) && isVptrCheckRequired(TCK, Ty)) {
// Ensure that the pointer is non-null before loading it. If there is no
// compile-time guarantee, reuse the run-time null check or emit a new one.
if (!IsGuaranteedNonNull) {

6
clang/lib/CodeGen/CodeGenFunction.h
View File

@ -2356,6 +2356,12 @@ public:
TCK_NonnullAssign
};
/// Determine whether the pointer type check \p TCK permits null pointers.
static bool isNullPointerAllowed(TypeCheckKind TCK);
/// Determine whether the pointer type check \p TCK requires a vptr check.
static bool isVptrCheckRequired(TypeCheckKind TCK, QualType Ty);
/// \brief Whether any type-checking sanitizers are enabled. If \c false,
/// calls to EmitTypeCheck can be skipped.
bool sanitizePerformTypeCheck() const;