[analyzer] Do not run visitors until the fixpoint, run only once.

In the current implementation, we run visitors until the fixed point is
reached.
That is, if a visitor adds another visitor, the currently processed path
is destroyed, all diagnostics is discarded, and it is regenerated again,
until it's no longer modified.
This pattern has a few negative implications:

 - This loop does not even guarantee to terminate.
   E.g. just imagine two visitors bouncing a diagnostics around.
 - Performance-wise, e.g. for sqlite3 all visitors are being re-run at
   least 10 times for some bugs.
   We have already seen a few reports where it leads to timeouts.
 - If we want to add more computationally intense visitors, this will
   become worse.
 - From architectural standpoint, the current layout requires copying
   visitors, which is conceptually wrong, and can be annoying (e.g. no
   unique_ptr on visitors allowed).

The proposed change is a much simpler architecture: the outer loop
processes nodes upwards, and whenever the visitor is added it only
processes current nodes and above, thus guaranteeing termination.

Differential Revision: https://reviews.llvm.org/D47856

llvm-svn: 335666

1 files changed, 1 insertions, 1 deletions

diff --git a/clang/lib/StaticAnalyzer/Checkers/DeleteWithNonVirtualDtorChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/DeleteWithNonVirtualDtorChecker.cpp
index 53632b41df4..d3489282ab6 100644
--- a/clang/lib/StaticAnalyzer/Checkers/DeleteWithNonVirtualDtorChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/DeleteWithNonVirtualDtorChecker.cpp
@@ -39,7 +39,7 @@ class DeleteWithNonVirtualDtorChecker
     : public Checker<check::PreStmt<CXXDeleteExpr>> {
   mutable std::unique_ptr<BugType> BT;
 
-  class DeleteBugVisitor : public BugReporterVisitorImpl<DeleteBugVisitor> {
+  class DeleteBugVisitor : public BugReporterVisitor {
   public:
     DeleteBugVisitor() : Satisfied(false) {}
     void Profile(llvm::FoldingSetNodeID &ID) const override {