r314750 - [ubsan] Add helpers to decide when null/vptr checks are required. NFC.

[Vedant Kumar via cfe-commits]

Author: vedantk
Date: Mon Oct  2 18:27:25 2017
New Revision: 314750

URL: http://llvm.org/viewvc/llvm-project?rev=314750&view=rev
Log:
[ubsan] Add helpers to decide when null/vptr checks are required. NFC.

Modified:
    cfe/trunk/lib/CodeGen/CGExpr.cpp
    cfe/trunk/lib/CodeGen/CodeGenFunction.h

Modified: cfe/trunk/lib/CodeGen/CGExpr.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGExpr.cpp?rev=314750&r1=314749&r2=314750&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGExpr.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGExpr.cpp Mon Oct  2 18:27:25 2017
@@ -569,6 +569,19 @@ static llvm::Value *emitHash16Bytes(CGBu
   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(Type
   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(Type
   //   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) {

Modified: cfe/trunk/lib/CodeGen/CodeGenFunction.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenFunction.h?rev=314750&r1=314749&r2=314750&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CodeGenFunction.h (original)
+++ cfe/trunk/lib/CodeGen/CodeGenFunction.h Mon Oct  2 18:27:25 2017
@@ -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;