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-rw-r--r--lib/StaticAnalyzer/Checkers/DeadStoresChecker.cpp106
1 files changed, 72 insertions, 34 deletions
diff --git a/lib/StaticAnalyzer/Checkers/DeadStoresChecker.cpp b/lib/StaticAnalyzer/Checkers/DeadStoresChecker.cpp
index d5baa2bcba6f..61441889fc64 100644
--- a/lib/StaticAnalyzer/Checkers/DeadStoresChecker.cpp
+++ b/lib/StaticAnalyzer/Checkers/DeadStoresChecker.cpp
@@ -11,6 +11,7 @@
//
//===----------------------------------------------------------------------===//
+#include "clang/Lex/Lexer.h"
#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Attr.h"
@@ -119,11 +120,20 @@ LookThroughTransitiveAssignmentsAndCommaOperators(const Expr *Ex) {
}
namespace {
+class DeadStoresChecker : public Checker<check::ASTCodeBody> {
+public:
+ bool ShowFixIts = false;
+ bool WarnForDeadNestedAssignments = true;
+
+ void checkASTCodeBody(const Decl *D, AnalysisManager &Mgr,
+ BugReporter &BR) const;
+};
+
class DeadStoreObs : public LiveVariables::Observer {
const CFG &cfg;
ASTContext &Ctx;
BugReporter& BR;
- const CheckerBase *Checker;
+ const DeadStoresChecker *Checker;
AnalysisDeclContext* AC;
ParentMap& Parents;
llvm::SmallPtrSet<const VarDecl*, 20> Escaped;
@@ -135,9 +145,10 @@ class DeadStoreObs : public LiveVariables::Observer {
public:
DeadStoreObs(const CFG &cfg, ASTContext &ctx, BugReporter &br,
- const CheckerBase *checker, AnalysisDeclContext *ac,
+ const DeadStoresChecker *checker, AnalysisDeclContext *ac,
ParentMap &parents,
- llvm::SmallPtrSet<const VarDecl *, 20> &escaped)
+ llvm::SmallPtrSet<const VarDecl *, 20> &escaped,
+ bool warnForDeadNestedAssignments)
: cfg(cfg), Ctx(ctx), BR(br), Checker(checker), AC(ac), Parents(parents),
Escaped(escaped), currentBlock(nullptr) {}
@@ -202,12 +213,32 @@ public:
llvm::raw_svector_ostream os(buf);
const char *BugType = nullptr;
+ SmallVector<FixItHint, 1> Fixits;
+
switch (dsk) {
- case DeadInit:
+ case DeadInit: {
BugType = "Dead initialization";
os << "Value stored to '" << *V
<< "' during its initialization is never read";
+
+ ASTContext &ACtx = V->getASTContext();
+ if (Checker->ShowFixIts) {
+ if (V->getInit()->HasSideEffects(ACtx,
+ /*IncludePossibleEffects=*/true)) {
+ break;
+ }
+ SourceManager &SM = ACtx.getSourceManager();
+ const LangOptions &LO = ACtx.getLangOpts();
+ SourceLocation L1 =
+ Lexer::findNextToken(
+ V->getTypeSourceInfo()->getTypeLoc().getEndLoc(),
+ SM, LO)->getEndLoc();
+ SourceLocation L2 =
+ Lexer::getLocForEndOfToken(V->getInit()->getEndLoc(), 1, SM, LO);
+ Fixits.push_back(FixItHint::CreateRemoval({L1, L2}));
+ }
break;
+ }
case DeadIncrement:
BugType = "Dead increment";
@@ -217,15 +248,20 @@ public:
os << "Value stored to '" << *V << "' is never read";
break;
+ // eg.: f((x = foo()))
case Enclosing:
- // Don't report issues in this case, e.g.: "if (x = foo())",
- // where 'x' is unused later. We have yet to see a case where
- // this is a real bug.
- return;
+ if (!Checker->WarnForDeadNestedAssignments)
+ return;
+ BugType = "Dead nested assignment";
+ os << "Although the value stored to '" << *V
+ << "' is used in the enclosing expression, the value is never "
+ "actually read from '"
+ << *V << "'";
+ break;
}
BR.EmitBasicReport(AC->getDecl(), Checker, BugType, "Dead store", os.str(),
- L, R);
+ L, R, Fixits);
}
void CheckVarDecl(const VarDecl *VD, const Expr *Ex, const Expr *Val,
@@ -471,35 +507,37 @@ public:
// DeadStoresChecker
//===----------------------------------------------------------------------===//
-namespace {
-class DeadStoresChecker : public Checker<check::ASTCodeBody> {
-public:
- void checkASTCodeBody(const Decl *D, AnalysisManager& mgr,
- BugReporter &BR) const {
-
- // Don't do anything for template instantiations.
- // Proving that code in a template instantiation is "dead"
- // means proving that it is dead in all instantiations.
- // This same problem exists with -Wunreachable-code.
- if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D))
- if (FD->isTemplateInstantiation())
- return;
+void DeadStoresChecker::checkASTCodeBody(const Decl *D, AnalysisManager &mgr,
+ BugReporter &BR) const {
- if (LiveVariables *L = mgr.getAnalysis<LiveVariables>(D)) {
- CFG &cfg = *mgr.getCFG(D);
- AnalysisDeclContext *AC = mgr.getAnalysisDeclContext(D);
- ParentMap &pmap = mgr.getParentMap(D);
- FindEscaped FS;
- cfg.VisitBlockStmts(FS);
- DeadStoreObs A(cfg, BR.getContext(), BR, this, AC, pmap, FS.Escaped);
- L->runOnAllBlocks(A);
- }
+ // Don't do anything for template instantiations.
+ // Proving that code in a template instantiation is "dead"
+ // means proving that it is dead in all instantiations.
+ // This same problem exists with -Wunreachable-code.
+ if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D))
+ if (FD->isTemplateInstantiation())
+ return;
+
+ if (LiveVariables *L = mgr.getAnalysis<LiveVariables>(D)) {
+ CFG &cfg = *mgr.getCFG(D);
+ AnalysisDeclContext *AC = mgr.getAnalysisDeclContext(D);
+ ParentMap &pmap = mgr.getParentMap(D);
+ FindEscaped FS;
+ cfg.VisitBlockStmts(FS);
+ DeadStoreObs A(cfg, BR.getContext(), BR, this, AC, pmap, FS.Escaped,
+ WarnForDeadNestedAssignments);
+ L->runOnAllBlocks(A);
}
-};
}
-void ento::registerDeadStoresChecker(CheckerManager &mgr) {
- mgr.registerChecker<DeadStoresChecker>();
+void ento::registerDeadStoresChecker(CheckerManager &Mgr) {
+ auto *Chk = Mgr.registerChecker<DeadStoresChecker>();
+
+ const AnalyzerOptions &AnOpts = Mgr.getAnalyzerOptions();
+ Chk->WarnForDeadNestedAssignments =
+ AnOpts.getCheckerBooleanOption(Chk, "WarnForDeadNestedAssignments");
+ Chk->ShowFixIts =
+ AnOpts.getCheckerBooleanOption(Chk, "ShowFixIts");
}
bool ento::shouldRegisterDeadStoresChecker(const LangOptions &LO) {