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