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clang-1/lib/Analysis/BugReporter.cpp

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C++
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// BugReporter.cpp - Generate PathDiagnostics for Bugs ------------*- 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 BugReporter, a utility class for generating
// PathDiagnostics for analyses based on GRSimpleVals.
//
//===----------------------------------------------------------------------===//
#include "clang/Analysis/PathSensitive/BugReporter.h"
#include "clang/Analysis/PathSensitive/GRExprEngine.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Basic/SourceLocation.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/CFG.h"
#include "clang/AST/Expr.h"
#include "clang/Analysis/ProgramPoint.h"
#include "clang/Analysis/PathDiagnostic.h"
#include "llvm/ADT/DenseMap.h"
#include <sstream>
using namespace clang;
BugReporter::~BugReporter() {}
GRBugReporter::~GRBugReporter() {}
BugReporterData::~BugReporterData() {}
BugType::~BugType() {}
BugReport::~BugReport() {}
RangedBugReport::~RangedBugReport() {}
ExplodedGraph<ValueState>& GRBugReporter::getGraph() {
return Eng.getGraph();
}
ValueStateManager& GRBugReporter::getStateManager() {
return Eng.getStateManager();
}
static inline Stmt* GetStmt(const ProgramPoint& P) {
if (const PostStmt* PS = dyn_cast<PostStmt>(&P)) {
return PS->getStmt();
}
else if (const BlockEdge* BE = dyn_cast<BlockEdge>(&P)) {
return BE->getSrc()->getTerminator();
}
else if (const BlockEntrance* BE = dyn_cast<BlockEntrance>(&P)) {
return BE->getFirstStmt();
}
assert (false && "Unsupported ProgramPoint.");
return NULL;
}
static inline Stmt* GetStmt(const CFGBlock* B) {
if (B->empty())
return const_cast<Stmt*>(B->getTerminator());
else
return (*B)[0];
}
static inline ExplodedNode<ValueState>*
GetNextNode(ExplodedNode<ValueState>* N) {
return N->pred_empty() ? NULL : *(N->pred_begin());
}
static Stmt* GetLastStmt(ExplodedNode<ValueState>* N) {
assert (isa<BlockEntrance>(N->getLocation()));
for (N = GetNextNode(N); N; N = GetNextNode(N)) {
ProgramPoint P = N->getLocation();
if (PostStmt* PS = dyn_cast<PostStmt>(&P))
return PS->getStmt();
}
return NULL;
}
static void ExecutionContinues(std::ostringstream& os, SourceManager& SMgr,
Stmt* S) {
if (!S)
return;
// Slow, but probably doesn't matter.
if (os.str().empty())
os << ' ';
os << "Execution continues on line "
<< SMgr.getLogicalLineNumber(S->getLocStart()) << '.';
}
static inline void ExecutionContinues(std::ostringstream& os,
SourceManager& SMgr,
ExplodedNode<ValueState>* N) {
ExecutionContinues(os, SMgr, GetStmt(N->getLocation()));
}
static inline void ExecutionContinues(std::ostringstream& os,
SourceManager& SMgr,
const CFGBlock* B) {
ExecutionContinues(os, SMgr, GetStmt(B));
}
Stmt* BugReport::getStmt(BugReporter& BR) const {
ProgramPoint ProgP = EndNode->getLocation();
Stmt *S = NULL;
if (BlockEntrance* BE = dyn_cast<BlockEntrance>(&ProgP))
if (BE->getBlock() == &BR.getCFG()->getExit())
S = GetLastStmt(EndNode);
if (!S)
S = GetStmt(ProgP);
return S;
}
PathDiagnosticPiece*
BugReport::getEndPath(BugReporter& BR,
ExplodedNode<ValueState>* EndPathNode) {
Stmt* S = getStmt(BR);
if (!S)
return NULL;
FullSourceLoc L(S->getLocStart(), BR.getContext().getSourceManager());
PathDiagnosticPiece* P = new PathDiagnosticPiece(L, getDescription());
const SourceRange *Beg, *End;
getRanges(BR, Beg, End);
for (; Beg != End; ++Beg)
P->addRange(*Beg);
return P;
}
void BugReport::getRanges(BugReporter& BR, const SourceRange*& beg,
const SourceRange*& end) {
if (Expr* E = dyn_cast_or_null<Expr>(getStmt(BR))) {
R = E->getSourceRange();
beg = &R;
end = beg+1;
}
else
beg = end = 0;
}
FullSourceLoc BugReport::getLocation(SourceManager& Mgr) {
if (!EndNode)
return FullSourceLoc();
Stmt* S = GetStmt(EndNode->getLocation());
if (!S)
return FullSourceLoc();
return FullSourceLoc(S->getLocStart(), Mgr);
}
PathDiagnosticPiece* BugReport::VisitNode(ExplodedNode<ValueState>* N,
ExplodedNode<ValueState>* PrevN,
ExplodedGraph<ValueState>& G,
BugReporter& BR) {
return NULL;
}
static std::pair<ExplodedGraph<ValueState>*, ExplodedNode<ValueState>*>
MakeReportGraph(ExplodedGraph<ValueState>* G, ExplodedNode<ValueState>* N) {
llvm::OwningPtr<ExplodedGraph<ValueState> > GTrim(G->Trim(&N, &N+1));
// Find the error node in the trimmed graph.
ExplodedNode<ValueState>* NOld = N;
N = 0;
for (ExplodedGraph<ValueState>::node_iterator
I = GTrim->nodes_begin(), E = GTrim->nodes_end(); I != E; ++I) {
if (I->getState() == NOld->getState() &&
I->getLocation() == NOld->getLocation()) {
N = &*I;
break;
}
}
assert(N);
// Create a new graph with a single path.
G = new ExplodedGraph<ValueState>(GTrim->getCFG(), GTrim->getCodeDecl(),
GTrim->getContext());
// Sometimes TrimGraph can contain a cycle. Perform a reverse DFS
// to the root node, and then construct a new graph that contains only
// a single path.
llvm::DenseMap<void*,unsigned> Visited;
llvm::SmallVector<ExplodedNode<ValueState>*, 10> WS;
WS.push_back(N);
unsigned cnt = 0;
ExplodedNode<ValueState>* Root = 0;
while (!WS.empty()) {
ExplodedNode<ValueState>* Node = WS.back();
WS.pop_back();
if (Visited.find(Node) != Visited.end())
continue;
Visited[Node] = cnt++;
if (Node->pred_empty()) {
Root = Node;
break;
}
for (ExplodedNode<ValueState>::pred_iterator I=Node->pred_begin(),
E=Node->pred_end(); I!=E; ++I)
WS.push_back(*I);
}
assert (Root);
// Now walk from the root down the DFS path, always taking the successor
// with the lowest number.
ExplodedNode<ValueState> *Last = 0, *First = 0;
for ( N = Root ;;) {
// Lookup the number associated with the current node.
llvm::DenseMap<void*,unsigned>::iterator I=Visited.find(N);
assert (I != Visited.end());
// Create the equivalent node in the new graph with the same state
// and location.
ExplodedNode<ValueState>* NewN =
G->getNode(N->getLocation(), N->getState());
// Link up the new node with the previous node.
if (Last)
NewN->addPredecessor(Last);
Last = NewN;
// Are we at the final node?
if (I->second == 0) {
First = NewN;
break;
}
// Find the next successor node. We choose the node that is marked
// with the lowest DFS number.
ExplodedNode<ValueState>::succ_iterator SI = N->succ_begin();
ExplodedNode<ValueState>::succ_iterator SE = N->succ_end();
N = 0;
for (unsigned MinVal = 0; SI != SE; ++SI) {
I = Visited.find(*SI);
if (I == Visited.end())
continue;
if (!N || I->second < MinVal) {
N = *SI;
MinVal = I->second;
}
}
assert (N);
}
assert (First);
return std::make_pair(G, First);
}
static VarDecl* GetMostRecentVarDeclBinding(ExplodedNode<ValueState>* N,
ValueStateManager& VMgr,
RVal X) {
for ( ; N ; N = N->pred_empty() ? 0 : *N->pred_begin()) {
ProgramPoint P = N->getLocation();
if (!isa<PostStmt>(P))
continue;
DeclRefExpr* DR = dyn_cast<DeclRefExpr>(cast<PostStmt>(P).getStmt());
if (!DR)
continue;
RVal Y = VMgr.GetRVal(N->getState(), DR);
if (X != Y)
continue;
VarDecl* VD = dyn_cast<VarDecl>(DR->getDecl());
if (!VD)
continue;
return VD;
}
return 0;
}
static void HandleNotableSymbol(ExplodedNode<ValueState>* N, Stmt* S,
SymbolID Sym, BugReporter& BR,
PathDiagnostic& PD) {
ExplodedNode<ValueState>* Pred = N->pred_empty() ? 0 : *N->pred_begin();
const ValueState* PrevSt = Pred ? Pred->getState() : 0;
if (!PrevSt)
return;
// Look at the variable bindings of the current state that map to the
// specified symbol. Are any of them not in the previous state.
const ValueState* St = N->getState();
ValueStateManager& VMgr = cast<GRBugReporter>(BR).getStateManager();
// FIXME: Later generalize for a broader memory model.
// FIXME: This is quadratic, since its nested in another loop. Probably
// doesn't matter, but keep an eye out for performance issues. It's
// also a bunch of copy-paste. Bad. Cleanup later.
for (ValueState::vb_iterator I=St->vb_begin(), E=St->vb_end(); I!=E; ++I){
RVal V = I.getData();
SymbolID ScanSym;
if (lval::SymbolVal* SV = dyn_cast<lval::SymbolVal>(&V))
ScanSym = SV->getSymbol();
else if (nonlval::SymbolVal* SV = dyn_cast<nonlval::SymbolVal>(&V))
ScanSym = SV->getSymbol();
else
continue;
if (ScanSym != Sym)
continue;
// Check if the previous state has this binding.
RVal X = VMgr.GetRVal(PrevSt, lval::DeclVal(I.getKey()));
if (X == V) // Same binding?
continue;
// Different binding. Only handle assignments for now. We don't pull
// this check out of the loop because we will eventually handle other
// cases.
VarDecl *VD = 0;
if (BinaryOperator* B = dyn_cast<BinaryOperator>(S)) {
if (!B->isAssignmentOp())
continue;
// What variable did we assign to?
DeclRefExpr* DR = dyn_cast<DeclRefExpr>(B->getLHS()->IgnoreParenCasts());
if (!DR)
continue;
VD = dyn_cast<VarDecl>(DR->getDecl());
}
else if (DeclStmt* DS = dyn_cast<DeclStmt>(S))
VD = dyn_cast<VarDecl>(DS->getDecl());
if (!VD)
continue;
// What is the most recently referenced variable with this binding?
VarDecl* MostRecent = GetMostRecentVarDeclBinding(Pred, VMgr, V);
if (!MostRecent)
continue;
// Create the diagnostic.
FullSourceLoc L(S->getLocStart(), BR.getSourceManager());
if (VD->getType()->isPointerLikeType()) {
std::string msg = "'" + std::string(VD->getName()) +
"' now aliases '" + MostRecent->getName() + "'";
PD.push_front(new PathDiagnosticPiece(L, msg));
}
}
}
void GRBugReporter::GeneratePathDiagnostic(PathDiagnostic& PD,
BugReport& R) {
ExplodedNode<ValueState>* N = R.getEndNode();
if (!N) return;
// Construct a new graph that contains only a single path from the error
// node to a root.
const std::pair<ExplodedGraph<ValueState>*,ExplodedNode<ValueState>*>
GPair = MakeReportGraph(&getGraph(), N);
llvm::OwningPtr<ExplodedGraph<ValueState> > ReportGraph(GPair.first);
assert(GPair.second->getLocation() == N->getLocation());
N = GPair.second;
// Start building the path diagnostic...
if (PathDiagnosticPiece* Piece = R.getEndPath(*this, N))
PD.push_back(Piece);
else
return;
ExplodedNode<ValueState>* NextNode = N->pred_empty()
? NULL : *(N->pred_begin());
ASTContext& Ctx = getContext();
SourceManager& SMgr = Ctx.getSourceManager();
while (NextNode) {
ExplodedNode<ValueState>* LastNode = N;
N = NextNode;
NextNode = GetNextNode(N);
ProgramPoint P = N->getLocation();
if (const BlockEdge* BE = dyn_cast<BlockEdge>(&P)) {
CFGBlock* Src = BE->getSrc();
CFGBlock* Dst = BE->getDst();
Stmt* T = Src->getTerminator();
if (!T)
continue;
FullSourceLoc L(T->getLocStart(), SMgr);
switch (T->getStmtClass()) {
default:
break;
case Stmt::GotoStmtClass:
case Stmt::IndirectGotoStmtClass: {
Stmt* S = GetStmt(LastNode->getLocation());
if (!S)
continue;
std::ostringstream os;
os << "Control jumps to line "
<< SMgr.getLogicalLineNumber(S->getLocStart()) << ".\n";
PD.push_front(new PathDiagnosticPiece(L, os.str()));
break;
}
case Stmt::SwitchStmtClass: {
// Figure out what case arm we took.
std::ostringstream os;
if (Stmt* S = Dst->getLabel())
switch (S->getStmtClass()) {
default:
assert(false && "Not a valid switch label.");
continue;
case Stmt::DefaultStmtClass: {
os << "Control jumps to the 'default' case at line "
<< SMgr.getLogicalLineNumber(S->getLocStart()) << ".\n";
break;
}
case Stmt::CaseStmtClass: {
os << "Control jumps to 'case ";
CaseStmt* Case = cast<CaseStmt>(S);
Expr* LHS = Case->getLHS()->IgnoreParenCasts();
// Determine if it is an enum.
bool GetRawInt = true;
if (DeclRefExpr* DR = dyn_cast<DeclRefExpr>(LHS)) {
// FIXME: Maybe this should be an assertion. Are there cases
// were it is not an EnumConstantDecl?
EnumConstantDecl* D = dyn_cast<EnumConstantDecl>(DR->getDecl());
if (D) {
GetRawInt = false;
os << D->getName();
}
}
if (GetRawInt) {
// Not an enum.
Expr* CondE = cast<SwitchStmt>(T)->getCond();
unsigned bits = Ctx.getTypeSize(CondE->getType());
llvm::APSInt V(bits, false);
if (!LHS->isIntegerConstantExpr(V, Ctx, 0, true)) {
assert (false && "Case condition must be constant.");
continue;
}
os << V.toString();
}
os << ":' at line "
<< SMgr.getLogicalLineNumber(S->getLocStart()) << ".\n";
break;
}
}
else {
os << "'Default' branch taken.";
ExecutionContinues(os, SMgr, LastNode);
}
PD.push_front(new PathDiagnosticPiece(L, os.str()));
break;
}
case Stmt::BreakStmtClass:
case Stmt::ContinueStmtClass: {
std::ostringstream os;
ExecutionContinues(os, SMgr, LastNode);
PD.push_front(new PathDiagnosticPiece(L, os.str()));
break;
}
case Stmt::ConditionalOperatorClass: {
std::ostringstream os;
os << "'?' condition evaluates to ";
if (*(Src->succ_begin()+1) == Dst)
os << "false.";
else
os << "true.";
PD.push_front(new PathDiagnosticPiece(L, os.str()));
break;
}
case Stmt::DoStmtClass: {
if (*(Src->succ_begin()) == Dst) {
std::ostringstream os;
os << "Loop condition is true.";
ExecutionContinues(os, SMgr, Dst);
PD.push_front(new PathDiagnosticPiece(L, os.str()));
}
else
PD.push_front(new PathDiagnosticPiece(L,
"Loop condition is false. Exiting loop."));
break;
}
case Stmt::WhileStmtClass:
case Stmt::ForStmtClass: {
if (*(Src->succ_begin()+1) == Dst) {
std::ostringstream os;
os << "Loop condition is false.";
ExecutionContinues(os, SMgr, Dst);
PD.push_front(new PathDiagnosticPiece(L, os.str()));
}
else
PD.push_front(new PathDiagnosticPiece(L,
"Loop condition is true. Entering loop body."));
break;
}
case Stmt::IfStmtClass: {
if (*(Src->succ_begin()+1) == Dst)
PD.push_front(new PathDiagnosticPiece(L, "Taking false branch."));
else
PD.push_front(new PathDiagnosticPiece(L, "Taking true branch."));
break;
}
}
}
if (PathDiagnosticPiece* p = R.VisitNode(N, NextNode, *ReportGraph, *this))
PD.push_front(p);
if (const PostStmt* PS = dyn_cast<PostStmt>(&P)) {
const ValueState* St = N->getState();
// Scan the lval bindings, and see if a "notable" symbol has a new
// lval binding.
// FIXME: In the future, when we generalize the memory model, we'll
// need a way to iterate over binded locations.
llvm::SmallSet<SymbolID, 10> AlreadyProcessed;
for (ValueState::vb_iterator I=St->vb_begin(), E=St->vb_end(); I!=E; ++I){
RVal V = I.getData();
SymbolID ScanSym;
if (lval::SymbolVal* SV = dyn_cast<lval::SymbolVal>(&V))
ScanSym = SV->getSymbol();
else if (nonlval::SymbolVal* SV = dyn_cast<nonlval::SymbolVal>(&V))
ScanSym = SV->getSymbol();
else
continue;
assert (ScanSym.isInitialized());
if (!isNotable(ScanSym))
continue;
if (AlreadyProcessed.count(ScanSym))
continue;
AlreadyProcessed.insert(ScanSym);
HandleNotableSymbol(N, PS->getStmt(), ScanSym, *this, PD);
}
}
}
}
bool BugTypeCacheLocation::isCached(BugReport& R) {
ExplodedNode<ValueState>* N = R.getEndNode();
if (!N)
return false;
// Cache the location of the error. Don't emit the same
// warning for the same error type that occurs at the same program
// location but along a different path.
return isCached(N->getLocation());
}
bool BugTypeCacheLocation::isCached(ProgramPoint P) {
void* p = P.getRawData();
if (CachedErrors.count(p))
return true;
CachedErrors.insert(p);
return false;
}
void BugReporter::EmitWarning(BugReport& R) {
if (R.getBugType().isCached(R))
return;
llvm::OwningPtr<PathDiagnostic> D(new PathDiagnostic(R.getName()));
GeneratePathDiagnostic(*D.get(), R);
// Get the meta data.
std::pair<const char**, const char**> Meta = R.getExtraDescriptiveText();
for (const char** s = Meta.first; s != Meta.second; ++s)
D->addMeta(*s);
// Emit a full diagnostic for the path if we have a PathDiagnosticClient.
PathDiagnosticClient* PD = getPathDiagnosticClient();
if (PD && !D->empty()) {
PD->HandlePathDiagnostic(D.take());
return;
}
// We don't have a PathDiagnosticClient, but we can still emit a single
// line diagnostic. Determine the location.
FullSourceLoc L = D->empty() ? R.getLocation(getSourceManager())
: D->back()->getLocation();
// Determine the range.
const SourceRange *Beg, *End;
if (!D->empty()) {
Beg = D->back()->ranges_begin();
End = D->back()->ranges_end();
}
else
R.getRanges(*this, Beg, End);
if (PD) {
PathDiagnosticPiece* piece = new PathDiagnosticPiece(L, R.getDescription());
for ( ; Beg != End; ++Beg)
piece->addRange(*Beg);
D->push_back(piece);
PD->HandlePathDiagnostic(D.take());
}
else {
std::ostringstream os;
if (D->empty())
os << R.getDescription();
else
os << D->back()->getString();
Diagnostic& Diag = getDiagnostic();
unsigned ErrorDiag = Diag.getCustomDiagID(Diagnostic::Warning,
os.str().c_str());
Diag.Report(L, ErrorDiag, NULL, 0, Beg, End - Beg);
}
}
void
BugReporter::EmitBasicReport(const char* name, const char* str,
SourceLocation Loc,
SourceRange* RBeg, unsigned NumRanges) {
SimpleBugType BT(name);
DiagCollector C(BT);
Diagnostic& Diag = getDiagnostic();
Diag.Report(&C, getContext().getFullLoc(Loc),
Diag.getCustomDiagID(Diagnostic::Warning, str),
0, 0, RBeg, NumRanges);
for (DiagCollector::iterator I = C.begin(), E = C.end(); I != E; ++I)
EmitWarning(*I);
}
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