Author: dergachev Date: Wed Jan 17 16:44:41 2018 New Revision: 322795 URL: http://llvm.org/viewvc/llvm-project?rev=322795&view=rev Log: [analyzer] Suppress "this" pointer escape during construction.
Pointer escape event notifies checkers that a pointer can no longer be reliably tracked by the analyzer. For example, if a pointer is passed into a function that has no body available, or written into a global, MallocChecker would no longer report memory leaks for such pointer. In case of operator new() under -analyzer-config c++-allocator-inlining=true, MallocChecker would start tracking the pointer allocated by operator new() only to immediately meet a pointer escape event notifying the checker that the pointer has escaped into a constructor (assuming that the body of the constructor is not available) and immediately stop tracking it. Even though it is theoretically possible for such constructor to put "this" into a global container that would later be freed, we prefer to preserve the old behavior of MallocChecker, i.e. a memory leak warning, in order to be able to find any memory leaks in C++ at all. In fact, c++-allocator-inlining *reduces* the amount of false positives coming from this-pointers escaping in constructors, because it'd be able to inline constructors in some cases. With other checkers working similarly, we simply suppress the escape event for this-value of the constructor, regardless of analyzer options. Differential Revision: https://reviews.llvm.org/D41797 rdar://problem/12180598 Modified: cfe/trunk/lib/StaticAnalyzer/Core/CallEvent.cpp cfe/trunk/test/Analysis/NewDeleteLeaks-PR19102.cpp Modified: cfe/trunk/lib/StaticAnalyzer/Core/CallEvent.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/StaticAnalyzer/Core/CallEvent.cpp?rev=322795&r1=322794&r2=322795&view=diff ============================================================================== --- cfe/trunk/lib/StaticAnalyzer/Core/CallEvent.cpp (original) +++ cfe/trunk/lib/StaticAnalyzer/Core/CallEvent.cpp Wed Jan 17 16:44:41 2018 @@ -672,8 +672,13 @@ SVal CXXConstructorCall::getCXXThisVal() void CXXConstructorCall::getExtraInvalidatedValues(ValueList &Values, RegionAndSymbolInvalidationTraits *ETraits) const { - if (Data) - Values.push_back(loc::MemRegionVal(static_cast<const MemRegion *>(Data))); + if (Data) { + loc::MemRegionVal MV(static_cast<const MemRegion *>(Data)); + if (SymbolRef Sym = MV.getAsSymbol(true)) + ETraits->setTrait(Sym, + RegionAndSymbolInvalidationTraits::TK_SuppressEscape); + Values.push_back(MV); + } } void CXXConstructorCall::getInitialStackFrameContents( Modified: cfe/trunk/test/Analysis/NewDeleteLeaks-PR19102.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Analysis/NewDeleteLeaks-PR19102.cpp?rev=322795&r1=322794&r2=322795&view=diff ============================================================================== --- cfe/trunk/test/Analysis/NewDeleteLeaks-PR19102.cpp (original) +++ cfe/trunk/test/Analysis/NewDeleteLeaks-PR19102.cpp Wed Jan 17 16:44:41 2018 @@ -1,4 +1,5 @@ // RUN: %clang_analyze_cc1 -analyzer-checker=core,cplusplus.NewDeleteLeaks -verify %s +// RUN: %clang_analyze_cc1 -analyzer-checker=core,cplusplus.NewDeleteLeaks -analyzer-config c++-allocator-inlining=true -verify %s class A0 {}; _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
