Added more checking in "dead stores" for values that are initialized

but never used.

Fix a bug in LiveVariables where uses on the LHS of self-assign
operators (e.g +=, *=, etc) would not be properly recorded in the
liveness state of the variable.

llvm-svn: 41757

2 files changed, 17 insertions, 1 deletions

diff --git a/clang/Analysis/DeadStores.cpp b/clang/Analysis/DeadStores.cpp
index e7077ecae31..f79aa6ae047 100644
--- a/clang/Analysis/DeadStores.cpp
+++ b/clang/Analysis/DeadStores.cpp
@@ -47,6 +47,19 @@ public:
         }
       }
     }
+    else if(DeclStmt* DS = dyn_cast<DeclStmt>(S)) {
+      // Iterate through the decls.  Warn if any of them (which have
+      // initializers) are not live.
+      for (Decl* D = DS->getDecl() ; D != NULL ; D = D->getNextDeclarator())
+        if (VarDecl* V = dyn_cast<VarDecl>(D))
+          if (Expr* E = V->getInit())
+            if (!L.isLive(Live,D)) {
+              SourceRange R = E->getSourceRange();
+              PP.getDiagnostics().Report(D->getLocation(),
+                                         diag::warn_dead_store, 0, 0,
+                                         &R,1);
+            }
+    }
   }
 };
   
diff --git a/clang/Analysis/LiveVariables.cpp b/clang/Analysis/LiveVariables.cpp
index 6b25f9eee60..bf4437470e3 100644
--- a/clang/Analysis/LiveVariables.cpp
+++ b/clang/Analysis/LiveVariables.cpp
@@ -252,7 +252,10 @@ void LivenessTFuncs::VisitAssign(BinaryOperator* B) {
     // We only need to register kills once, so we check if this block
     // has been previously processed.
     if (!blockPreviouslyProcessed)
-      V.AddKill(CurrentStmt,DR);    
+      V.AddKill(CurrentStmt,DR);
+      
+    if (B->getOpcode() != BinaryOperator::Assign)
+      Visit(LHS);
   }
   else
     Visit(LHS);