[analyzer] Do not invalidate the `this` pointer.

Summary:
`this` pointer is not an l-value, although we have modeled `CXXThisRegion` for `this` pointer, we can only bind it once, which is when we start to inline method. And this patch fixes https://bugs.llvm.org/show_bug.cgi?id=35506.

In addition, I didn't find any other cases other than loop-widen that could invalidate `this` pointer.

Reviewers: NoQ, george.karpenkov, a.sidorin, seaneveson, szepet

Reviewed By: NoQ

Subscribers: xazax.hun, rnkovacs, cfe-commits, MTC

Differential Revision: https://reviews.llvm.org/D45491

llvm-svn: 330095

1 files changed, 12 insertions, 0 deletions

diff --git a/clang/lib/StaticAnalyzer/Core/LoopWidening.cpp b/clang/lib/StaticAnalyzer/Core/LoopWidening.cpp
index 05865c294cb..a609aa96d77 100644
--- a/clang/lib/StaticAnalyzer/Core/LoopWidening.cpp
+++ b/clang/lib/StaticAnalyzer/Core/LoopWidening.cpp
@@ -59,6 +59,18 @@ ProgramStateRef getWidenedLoopState(ProgramStateRef PrevState,
     ITraits.setTrait(Region,
                      RegionAndSymbolInvalidationTraits::TK_EntireMemSpace);
   }
+
+  // 'this' pointer is not an lvalue, we should not invalidate it. If the loop
+  // is located in a method, constructor or destructor, the value of 'this'
+  // pointer shoule remain unchanged.
+  if (const CXXMethodDecl *CXXMD = dyn_cast<CXXMethodDecl>(STC->getDecl())) {
+    const CXXThisRegion *ThisR = MRMgr.getCXXThisRegion(
+        CXXMD->getThisType(STC->getAnalysisDeclContext()->getASTContext()),
+        STC);
+    ITraits.setTrait(ThisR,
+                     RegionAndSymbolInvalidationTraits::TK_PreserveContents);
+  }
+
   return PrevState->invalidateRegions(Regions, getLoopCondition(LoopStmt),
                                       BlockCount, LCtx, true, nullptr, nullptr,
                                       &ITraits);