[analyzer] RetainCount: Add support for OSRequiredCast().

It's a new API for custom RTTI in Apple IOKit/DriverKit framework that is
similar to OSDynamicCast() that's already supported, but crashes instead of
returning null (and therefore causing UB when the cast fails unexpectedly).
Kind of like cast_or_null<> as opposed to dyn_cast_or_null<> in LLVM's RTTI.

Historically, RetainCountChecker was responsible for modeling OSDynamicCast.
This is simply an extension of the same functionality.

Differential Revision: https://reviews.llvm.org/D63117

llvm-svn: 363891

1 files changed, 8 insertions, 1 deletions

diff --git a/clang/lib/Analysis/RetainSummaryManager.cpp b/clang/lib/Analysis/RetainSummaryManager.cpp
index 4f0fced60bf..132053fd2c2 100644
--- a/clang/lib/Analysis/RetainSummaryManager.cpp
+++ b/clang/lib/Analysis/RetainSummaryManager.cpp
@@ -152,6 +152,10 @@ static bool isOSObjectDynamicCast(StringRef S) {
   return S == "safeMetaCast";
 }
 
+static bool isOSObjectRequiredCast(StringRef S) {
+  return S == "requiredMetaCast";
+}
+
 static bool isOSObjectThisCast(StringRef S) {
   return S == "metaCast";
 }
@@ -234,7 +238,8 @@ RetainSummaryManager::getSummaryForOSObject(const FunctionDecl *FD,
   if (RetTy->isPointerType()) {
     const CXXRecordDecl *PD = RetTy->getPointeeType()->getAsCXXRecordDecl();
     if (PD && isOSObjectSubclass(PD)) {
-      if (isOSObjectDynamicCast(FName) || isOSObjectThisCast(FName))
+      if (isOSObjectDynamicCast(FName) || isOSObjectRequiredCast(FName) ||
+          isOSObjectThisCast(FName))
         return getDefaultSummary();
 
       // TODO: Add support for the slightly common *Matching(table) idiom.
@@ -745,6 +750,8 @@ RetainSummaryManager::canEval(const CallExpr *CE, const FunctionDecl *FD,
     if (TrackOSObjects) {
       if (isOSObjectDynamicCast(FName) && FD->param_size() >= 1) {
         return BehaviorSummary::IdentityOrZero;
+      } else if (isOSObjectRequiredCast(FName) && FD->param_size() >= 1) {
+        return BehaviorSummary::Identity;
       } else if (isOSObjectThisCast(FName) && isa<CXXMethodDecl>(FD) &&
                  !cast<CXXMethodDecl>(FD)->isStatic()) {
         return BehaviorSummary::IdentityThis;