1 files changed, 87 insertions, 0 deletions
diff --git a/clang/lib/Analysis/DeadStores.cpp b/clang/lib/Analysis/DeadStores.cpp
new file mode 100644
index 00000000000..0848336e586
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+++ b/clang/lib/Analysis/DeadStores.cpp
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+//==- DeadStores.cpp - Check for stores to dead variables --------*- C++ -*-==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file defines a DeadStores, a flow-sensitive checker that looks for
+//  stores to variables that are no longer live.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Analysis/LocalCheckers.h"
+#include "clang/Analysis/Analyses/LiveVariables.h"
+#include "clang/Analysis/Visitors/CFGRecStmtVisitor.h"
+#include "clang/Basic/Diagnostic.h"
+#include "clang/AST/ASTContext.h"
+#include "llvm/Support/Compiler.h"
+
+using namespace clang;
+
+namespace {
+  
+class VISIBILITY_HIDDEN DeadStoreObs : public LiveVariables::ObserverTy {
+  ASTContext &Ctx;
+  Diagnostic &Diags;
+public:
+  DeadStoreObs(ASTContext &ctx,Diagnostic &diags) : Ctx(ctx), Diags(diags){}    
+  virtual ~DeadStoreObs() {}
+  
+  virtual void ObserveStmt(Stmt* S,
+                           const LiveVariables::AnalysisDataTy& AD,
+                           const LiveVariables::ValTy& Live) {
+    
+    if (BinaryOperator* B = dyn_cast<BinaryOperator>(S)) {    
+      if (!B->isAssignmentOp()) return; // Skip non-assignments.
+      
+      if (DeclRefExpr* DR = dyn_cast<DeclRefExpr>(B->getLHS()))
+        if (VarDecl* VD = dyn_cast<VarDecl>(DR->getDecl()))
+          if (VD->hasLocalStorage() && !Live(VD,AD)) {
+            SourceRange R = B->getRHS()->getSourceRange();
+            Diags.Report(Ctx.getFullLoc(DR->getSourceRange().getBegin()),
+                         diag::warn_dead_store, 0, 0, &R, 1);                                                                        
+        }
+    }
+    else if(DeclStmt* DS = dyn_cast<DeclStmt>(S))
+      // Iterate through the decls.  Warn if any initializers are complex
+      // expressions that are not live (never used).
+      for (VarDecl* V = cast<VarDecl>(DS->getDecl()); V != NULL ; 
+                    V = cast_or_null<VarDecl>(V->getNextDeclarator())) {
+        if (V->hasLocalStorage())
+          if (Expr* E = V->getInit()) {
+            if (!Live(DS->getDecl(),AD)) {
+              // Special case: check for initializations with constants.
+              //
+              //  e.g. : int x = 0;
+              //
+              // If x is EVER assigned a new value later, don't issue
+              // a warning.  This is because such initialization can be
+              // due to defensive programming.
+              if (!E->isConstantExpr(Ctx,NULL)) {
+                // Flag a warning.
+                SourceRange R = E->getSourceRange();
+                Diags.Report(Ctx.getFullLoc(V->getLocation()),
+                             diag::warn_dead_store, 0, 0, &R, 1);
+              }
+            }
+          }
+      }
+  }
+};
+  
+} // end anonymous namespace
+
+namespace clang {
+
+void CheckDeadStores(CFG& cfg, ASTContext &Ctx, Diagnostic &Diags) {
+  
+  LiveVariables L(cfg);
+  L.runOnCFG(cfg);
+  DeadStoreObs A(Ctx, Diags);
+  L.runOnAllBlocks(cfg, &A);
+}
+
+} // end namespace clang