Bail out the LiveVariables analysis when the CFG is very large, as

we are encountering some scalability issues with memory usage.   The
appropriate long term fix is to make the analysis more scalable, but
this will at least prevent the analyzer swapping when
analyzing very large functions.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@159578 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 15 insertions, 0 deletions

diff --git a/lib/Analysis/LiveVariables.cpp b/lib/Analysis/LiveVariables.cpp
index ff6607d51a..6e10ac1092 100644
--- a/lib/Analysis/LiveVariables.cpp
+++ b/lib/Analysis/LiveVariables.cpp
@@ -486,6 +486,11 @@ LiveVariables::computeLiveness(AnalysisDeclContext &AC,
   if (!cfg)
     return 0;
 
+  // The analysis currently has scalability issues for very large CFGs.
+  // Bail out if it looks too large.
+  if (cfg->getNumBlockIDs() > 300000)
+    return 0;
+
   LiveVariablesImpl *LV = new LiveVariablesImpl(AC, killAtAssign);
 
   // Construct the dataflow worklist.  Enqueue the exit block as the
diff --git a/lib/StaticAnalyzer/Core/ExprEngineCallAndReturn.cpp b/lib/StaticAnalyzer/Core/ExprEngineCallAndReturn.cpp
index 3761f9c10a..44b4e31f03 100644
--- a/lib/StaticAnalyzer/Core/ExprEngineCallAndReturn.cpp
+++ b/lib/StaticAnalyzer/Core/ExprEngineCallAndReturn.cpp
@@ -11,6 +11,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "clang/Analysis/Analyses/LiveVariables.h"
 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/Calls.h"
@@ -244,6 +245,11 @@ bool ExprEngine::shouldInlineDecl(const Decl *D, ExplodedNode *Pred) {
   if (isa<CXXConstructorDecl>(D))
     return false;
 
+  // It is possible that the live variables analysis cannot be
+  // run.  If so, bail out.
+  if (!CalleeADC->getAnalysis<RelaxedLiveVariables>())
+    return false;
+
   return true;
 }
 
diff --git a/lib/StaticAnalyzer/Frontend/AnalysisConsumer.cpp b/lib/StaticAnalyzer/Frontend/AnalysisConsumer.cpp
index 05fb0155f1..520a975bda 100644
--- a/lib/StaticAnalyzer/Frontend/AnalysisConsumer.cpp
+++ b/lib/StaticAnalyzer/Frontend/AnalysisConsumer.cpp
@@ -523,6 +523,10 @@ void AnalysisConsumer::ActionExprEngine(Decl *D, bool ObjCGCEnabled,
   if (!Mgr->getCFG(D))
     return;
 
+  // See if the LiveVariables analysis scales.
+  if (!Mgr->getAnalysisDeclContext(D)->getAnalysis<RelaxedLiveVariables>())
+    return;
+
   ExprEngine Eng(*Mgr, ObjCGCEnabled, VisitedCallees, &FunctionSummaries);
 
   // Set the graph auditor.