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Emit dead store warnings for ++ and -- operators. 

llvm-svn: 50679
This commit is contained in:
Ted Kremenek 2008-05-05 23:12:21 +00:00
parent 310a38d51e
commit f15cd14a3d
2 changed files with 32 additions and 9 deletions
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32
clang/lib/Analysis/DeadStores.cpp
View File

@ -35,6 +35,19 @@ public:
virtual ~DeadStoreObs() {}
void CheckDeclRef(DeclRefExpr* DR, Expr* Val,
const LiveVariables::AnalysisDataTy& AD,
const LiveVariables::ValTy& Live) {
if (VarDecl* VD = dyn_cast<VarDecl>(DR->getDecl()))
if (VD->hasLocalStorage() && !Live(VD, AD)) {
SourceRange R = Val->getSourceRange();
Diags.Report(&Client,
Ctx.getFullLoc(DR->getSourceRange().getBegin()),
diag::warn_dead_store, 0, 0, &R, 1);
}
}
virtual void ObserveStmt(Stmt* S,
const LiveVariables::AnalysisDataTy& AD,
const LiveVariables::ValTy& Live) {
@ -47,15 +60,18 @@ public:
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(&Client,
Ctx.getFullLoc(DR->getSourceRange().getBegin()),
diag::warn_dead_store, 0, 0, &R, 1);
}
CheckDeclRef(DR, B->getRHS(), AD, Live);
}
else if(DeclStmt* DS = dyn_cast<DeclStmt>(S))
else if (UnaryOperator* U = dyn_cast<UnaryOperator>(S)) {
if (!U->isIncrementOp())
return;
Expr *Ex = U->getSubExpr()->IgnoreParenCasts();
if (DeclRefExpr* DR = dyn_cast<DeclRefExpr>(Ex))
CheckDeclRef(DR, U, AD, Live);
}
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 (ScopedDecl* SD = DS->getDecl(); SD; SD = SD->getNextDeclarator()) {

9
clang/test/Analysis/dead-stores.c
View File

@ -35,4 +35,11 @@ void f5() {
int x = 4; // no-warning
int *p = &x; // expected-warning{{value stored to variable is never used}}
}
}
int f6() {
int x = 4;
++x; // expected-warning{{value stored to variable is never used}}
return 1;
}