1 files changed, 38 insertions, 3 deletions

diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index 8661251000d..276716ffb76 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -952,15 +952,46 @@ LValue CodeGenFunction::EmitUnsupportedLValue(const Expr *E,
                         E->getType());
 }
 
+bool CodeGenFunction::CanElideObjectPointerNullCheck(const Expr *Obj) {
+  if (isa<DeclRefExpr>(Obj))
+    return true;
+
+  const Expr *Base = Obj;
+  while (!isa<CXXThisExpr>(Base)) {
+    // The result of a dynamic_cast can be null.
+    if (isa<CXXDynamicCastExpr>(Base))
+      return false;
+
+    if (const auto *CE = dyn_cast<CastExpr>(Base)) {
+      Base = CE->getSubExpr();
+    } else if (const auto *PE = dyn_cast<ParenExpr>(Base)) {
+      Base = PE->getSubExpr();
+    } else if (const auto *UO = dyn_cast<UnaryOperator>(Base)) {
+      if (UO->getOpcode() == UO_Extension)
+        Base = UO->getSubExpr();
+      else
+        return false;
+    } else {
+      return false;
+    }
+  }
+  return true;
+}
+
 LValue CodeGenFunction::EmitCheckedLValue(const Expr *E, TypeCheckKind TCK) {
   LValue LV;
   if (SanOpts.has(SanitizerKind::ArrayBounds) && isa<ArraySubscriptExpr>(E))
     LV = EmitArraySubscriptExpr(cast<ArraySubscriptExpr>(E), /*Accessed*/true);
   else
     LV = EmitLValue(E);
-  if (!isa<DeclRefExpr>(E) && !LV.isBitField() && LV.isSimple())
+  if (!isa<DeclRefExpr>(E) && !LV.isBitField() && LV.isSimple()) {
+    SanitizerSet SkippedChecks;
+    if (const auto *ME = dyn_cast<MemberExpr>(E))
+      if (CanElideObjectPointerNullCheck(ME->getBase()))
+        SkippedChecks.set(SanitizerKind::Null, true);
     EmitTypeCheck(TCK, E->getExprLoc(), LV.getPointer(),
-                  E->getType(), LV.getAlignment());
+                  E->getType(), LV.getAlignment(), SkippedChecks);
+  }
   return LV;
 }
 
@@ -3340,7 +3371,11 @@ LValue CodeGenFunction::EmitMemberExpr(const MemberExpr *E) {
     AlignmentSource AlignSource;
     Address Addr = EmitPointerWithAlignment(BaseExpr, &AlignSource);
     QualType PtrTy = BaseExpr->getType()->getPointeeType();
-    EmitTypeCheck(TCK_MemberAccess, E->getExprLoc(), Addr.getPointer(), PtrTy);
+    SanitizerSet SkippedChecks;
+    if (CanElideObjectPointerNullCheck(BaseExpr))
+      SkippedChecks.set(SanitizerKind::Null, true);
+    EmitTypeCheck(TCK_MemberAccess, E->getExprLoc(), Addr.getPointer(), PtrTy,
+                  /*Alignment=*/CharUnits::Zero(), SkippedChecks);
     BaseLV = MakeAddrLValue(Addr, PtrTy, AlignSource);
   } else
     BaseLV = EmitCheckedLValue(BaseExpr, TCK_MemberAccess);