commit ec49bf464c91a52b3a463940da6589d03bf40248
author Tom Care <tom.care@uqconnect.edu.au> Fri Aug 27 22:30:10 2010 +0000
committer Tom Care <tom.care@uqconnect.edu.au> Fri Aug 27 22:30:10 2010 +0000
tree 961d9027718623da4123f7ac0c884643db73f338
parent 585b318a7333b5dd1d900881db7b6610e2701fe8

Add alternate version of LiveVariables analysis that does not kill liveness at assignments. This 'relaxed' liveness is useful in path sensitive analysis for situations where the resulting extended liveness allows us to find some bugs.
- Added killAtAssign flag to LiveVariables
- Added relaxed LiveVariables to AnalysisContext with an accessor

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@112306 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Analysis/AnalysisContext.cpp

diff --git a/lib/Analysis/AnalysisContext.cpp b/lib/Analysis/AnalysisContext.cpp
index 2c337f0..884cbc6 100644
--- a/lib/Analysis/AnalysisContext.cpp
+++ b/lib/Analysis/AnalysisContext.cpp
@@ -104,6 +104,20 @@
   return liveness;
 }
 
+LiveVariables *AnalysisContext::getRelaxedLiveVariables() {
+  if (!relaxedLiveness) {
+    CFG *c = getCFG();
+    if (!c)
+      return 0;
+
+    relaxedLiveness = new LiveVariables(*this, false);
+    relaxedLiveness->runOnCFG(*c);
+    relaxedLiveness->runOnAllBlocks(*c, 0, true);
+  }
+
+  return relaxedLiveness;
+}
+
 AnalysisContext *AnalysisContextManager::getContext(const Decl *D,
                                                     idx::TranslationUnit *TU) {
   AnalysisContext *&AC = Contexts[D];

lib/Analysis/LiveVariables.cpp

diff --git a/lib/Analysis/LiveVariables.cpp b/lib/Analysis/LiveVariables.cpp
index 3011fd0..47b2e3d 100644
--- a/lib/Analysis/LiveVariables.cpp
+++ b/lib/Analysis/LiveVariables.cpp
@@ -77,12 +77,13 @@
 };
 } // end anonymous namespace
 
-LiveVariables::LiveVariables(AnalysisContext &AC) {  
+LiveVariables::LiveVariables(AnalysisContext &AC, bool killAtAssign) {
   // Register all referenced VarDecls.
   CFG &cfg = *AC.getCFG();
   getAnalysisData().setCFG(cfg);
   getAnalysisData().setContext(AC.getASTContext());
   getAnalysisData().AC = ∾
+  getAnalysisData().killAtAssign = killAtAssign;
 
   RegisterDecls R(getAnalysisData());
   cfg.VisitBlockStmts(R);
@@ -260,12 +261,13 @@
     if (DR->getDecl()->getType()->isReferenceType()) {
       VisitDeclRefExpr(DR);
     } else {
-      // Update liveness inforamtion.
-      unsigned bit = AD.getIdx(DR->getDecl());
-      LiveState.getDeclBit(bit) = Dead | AD.AlwaysLive.getDeclBit(bit);
+      if (AD.killAtAssign) {
+        // Update liveness inforamtion.
+        unsigned bit = AD.getIdx(DR->getDecl());
+        LiveState.getDeclBit(bit) = Dead | AD.AlwaysLive.getDeclBit(bit);
 
-      if (AD.Observer) { AD.Observer->ObserverKill(DR); }
-
+        if (AD.Observer) { AD.Observer->ObserverKill(DR); }
+      }
       // Handle things like +=, etc., which also generate "uses"
       // of a variable.  Do this just by visiting the subexpression.
       if (B->getOpcode() != BO_Assign)