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llvm-project/clang/lib/Sema/AnalysisBasedWarnings.cpp

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//=- AnalysisBasedWarnings.cpp - Sema warnings based on libAnalysis -*- 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 analysis_warnings::[Policy,Executor].
// Together they are used by Sema to issue warnings based on inexpensive
// static analysis algorithms in libAnalysis.
//
//===----------------------------------------------------------------------===//
#include "clang/Sema/AnalysisBasedWarnings.h"
#include "clang/Sema/SemaInternal.h"
#include "clang/Sema/ScopeInfo.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Basic/SourceLocation.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/ExprObjC.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/StmtObjC.h"
#include "clang/AST/StmtCXX.h"
#include "clang/AST/EvaluatedExprVisitor.h"
#include "clang/AST/StmtVisitor.h"
#include "clang/Analysis/AnalysisContext.h"
#include "clang/Analysis/CFG.h"
#include "clang/Analysis/Analyses/ReachableCode.h"
#include "clang/Analysis/Analyses/CFGReachabilityAnalysis.h"
#include "clang/Analysis/Analyses/ThreadSafety.h"
#include "clang/Analysis/CFGStmtMap.h"
#include "clang/Analysis/Analyses/UninitializedValues.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/FoldingSet.h"
#include "llvm/ADT/ImmutableMap.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/Casting.h"
#include <algorithm>
#include <vector>
using namespace clang;
//===----------------------------------------------------------------------===//
// Unreachable code analysis.
//===----------------------------------------------------------------------===//
namespace {
class UnreachableCodeHandler : public reachable_code::Callback {
Sema &S;
public:
UnreachableCodeHandler(Sema &s) : S(s) {}
void HandleUnreachable(SourceLocation L, SourceRange R1, SourceRange R2) {
S.Diag(L, diag::warn_unreachable) << R1 << R2;
}
};
}
/// CheckUnreachable - Check for unreachable code.
static void CheckUnreachable(Sema &S, AnalysisDeclContext &AC) {
UnreachableCodeHandler UC(S);
reachable_code::FindUnreachableCode(AC, UC);
}
//===----------------------------------------------------------------------===//
// Check for missing return value.
//===----------------------------------------------------------------------===//
enum ControlFlowKind {
UnknownFallThrough,
NeverFallThrough,
MaybeFallThrough,
AlwaysFallThrough,
NeverFallThroughOrReturn
};
/// CheckFallThrough - Check that we don't fall off the end of a
/// Statement that should return a value.
///
/// \returns AlwaysFallThrough iff we always fall off the end of the statement,
/// MaybeFallThrough iff we might or might not fall off the end,
/// NeverFallThroughOrReturn iff we never fall off the end of the statement or
/// return. We assume NeverFallThrough iff we never fall off the end of the
/// statement but we may return. We assume that functions not marked noreturn
/// will return.
static ControlFlowKind CheckFallThrough(AnalysisDeclContext &AC) {
CFG *cfg = AC.getCFG();
if (cfg == 0) return UnknownFallThrough;
// The CFG leaves in dead things, and we don't want the dead code paths to
// confuse us, so we mark all live things first.
llvm::BitVector live(cfg->getNumBlockIDs());
unsigned count = reachable_code::ScanReachableFromBlock(&cfg->getEntry(),
live);
bool AddEHEdges = AC.getAddEHEdges();
if (!AddEHEdges && count != cfg->getNumBlockIDs())
// When there are things remaining dead, and we didn't add EH edges
// from CallExprs to the catch clauses, we have to go back and
// mark them as live.
for (CFG::iterator I = cfg->begin(), E = cfg->end(); I != E; ++I) {
CFGBlock &b = **I;
if (!live[b.getBlockID()]) {
if (b.pred_begin() == b.pred_end()) {
if (b.getTerminator() && isa<CXXTryStmt>(b.getTerminator()))
// When not adding EH edges from calls, catch clauses
// can otherwise seem dead. Avoid noting them as dead.
count += reachable_code::ScanReachableFromBlock(&b, live);
continue;
}
}
}
// Now we know what is live, we check the live precessors of the exit block
// and look for fall through paths, being careful to ignore normal returns,
// and exceptional paths.
bool HasLiveReturn = false;
bool HasFakeEdge = false;
bool HasPlainEdge = false;
bool HasAbnormalEdge = false;
// Ignore default cases that aren't likely to be reachable because all
// enums in a switch(X) have explicit case statements.
CFGBlock::FilterOptions FO;
FO.IgnoreDefaultsWithCoveredEnums = 1;
for (CFGBlock::filtered_pred_iterator
I = cfg->getExit().filtered_pred_start_end(FO); I.hasMore(); ++I) {
const CFGBlock& B = **I;
if (!live[B.getBlockID()])
continue;
// Skip blocks which contain an element marked as no-return. They don't
// represent actually viable edges into the exit block, so mark them as
// abnormal.
if (B.hasNoReturnElement()) {
HasAbnormalEdge = true;
continue;
}
// Destructors can appear after the 'return' in the CFG. This is
// normal. We need to look pass the destructors for the return
// statement (if it exists).
CFGBlock::const_reverse_iterator ri = B.rbegin(), re = B.rend();
for ( ; ri != re ; ++ri)
if (isa<CFGStmt>(*ri))
break;
// No more CFGElements in the block?
if (ri == re) {
if (B.getTerminator() && isa<CXXTryStmt>(B.getTerminator())) {
HasAbnormalEdge = true;
continue;
}
// A labeled empty statement, or the entry block...
HasPlainEdge = true;
continue;
}
CFGStmt CS = cast<CFGStmt>(*ri);
const Stmt *S = CS.getStmt();
if (isa<ReturnStmt>(S)) {
HasLiveReturn = true;
continue;
}
if (isa<ObjCAtThrowStmt>(S)) {
HasFakeEdge = true;
continue;
}
if (isa<CXXThrowExpr>(S)) {
HasFakeEdge = true;
continue;
}
if (const AsmStmt *AS = dyn_cast<AsmStmt>(S)) {
if (AS->isMSAsm()) {
HasFakeEdge = true;
HasLiveReturn = true;
continue;
}
}
if (isa<CXXTryStmt>(S)) {
HasAbnormalEdge = true;
continue;
}
if (std::find(B.succ_begin(), B.succ_end(), &cfg->getExit())
== B.succ_end()) {
HasAbnormalEdge = true;
continue;
}
HasPlainEdge = true;
}
if (!HasPlainEdge) {
if (HasLiveReturn)
return NeverFallThrough;
return NeverFallThroughOrReturn;
}
if (HasAbnormalEdge || HasFakeEdge || HasLiveReturn)
return MaybeFallThrough;
// This says AlwaysFallThrough for calls to functions that are not marked
// noreturn, that don't return. If people would like this warning to be more
// accurate, such functions should be marked as noreturn.
return AlwaysFallThrough;
}
namespace {
struct CheckFallThroughDiagnostics {
unsigned diag_MaybeFallThrough_HasNoReturn;
unsigned diag_MaybeFallThrough_ReturnsNonVoid;
unsigned diag_AlwaysFallThrough_HasNoReturn;
unsigned diag_AlwaysFallThrough_ReturnsNonVoid;
unsigned diag_NeverFallThroughOrReturn;
bool funMode;
SourceLocation FuncLoc;
static CheckFallThroughDiagnostics MakeForFunction(const Decl *Func) {
CheckFallThroughDiagnostics D;
D.FuncLoc = Func->getLocation();
D.diag_MaybeFallThrough_HasNoReturn =
diag::warn_falloff_noreturn_function;
D.diag_MaybeFallThrough_ReturnsNonVoid =
diag::warn_maybe_falloff_nonvoid_function;
D.diag_AlwaysFallThrough_HasNoReturn =
diag::warn_falloff_noreturn_function;
D.diag_AlwaysFallThrough_ReturnsNonVoid =
diag::warn_falloff_nonvoid_function;
// Don't suggest that virtual functions be marked "noreturn", since they
// might be overridden by non-noreturn functions.
bool isVirtualMethod = false;
if (const CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Func))
isVirtualMethod = Method->isVirtual();
// Don't suggest that template instantiations be marked "noreturn"
bool isTemplateInstantiation = false;
if (const FunctionDecl *Function = dyn_cast<FunctionDecl>(Func))
isTemplateInstantiation = Function->isTemplateInstantiation();
if (!isVirtualMethod && !isTemplateInstantiation)
D.diag_NeverFallThroughOrReturn =
diag::warn_suggest_noreturn_function;
else
D.diag_NeverFallThroughOrReturn = 0;
D.funMode = true;
return D;
}
static CheckFallThroughDiagnostics MakeForBlock() {
CheckFallThroughDiagnostics D;
D.diag_MaybeFallThrough_HasNoReturn =
diag::err_noreturn_block_has_return_expr;
D.diag_MaybeFallThrough_ReturnsNonVoid =
diag::err_maybe_falloff_nonvoid_block;
D.diag_AlwaysFallThrough_HasNoReturn =
diag::err_noreturn_block_has_return_expr;
D.diag_AlwaysFallThrough_ReturnsNonVoid =
diag::err_falloff_nonvoid_block;
D.diag_NeverFallThroughOrReturn =
diag::warn_suggest_noreturn_block;
D.funMode = false;
return D;
}
bool checkDiagnostics(DiagnosticsEngine &D, bool ReturnsVoid,
bool HasNoReturn) const {
if (funMode) {
return (ReturnsVoid ||
D.getDiagnosticLevel(diag::warn_maybe_falloff_nonvoid_function,
FuncLoc) == DiagnosticsEngine::Ignored)
&& (!HasNoReturn ||
D.getDiagnosticLevel(diag::warn_noreturn_function_has_return_expr,
FuncLoc) == DiagnosticsEngine::Ignored)
&& (!ReturnsVoid ||
D.getDiagnosticLevel(diag::warn_suggest_noreturn_block, FuncLoc)
== DiagnosticsEngine::Ignored);
}
// For blocks.
return ReturnsVoid && !HasNoReturn
&& (!ReturnsVoid ||
D.getDiagnosticLevel(diag::warn_suggest_noreturn_block, FuncLoc)
== DiagnosticsEngine::Ignored);
}
};
}
/// CheckFallThroughForFunctionDef - Check that we don't fall off the end of a
/// function that should return a value. Check that we don't fall off the end
/// of a noreturn function. We assume that functions and blocks not marked
/// noreturn will return.
static void CheckFallThroughForBody(Sema &S, const Decl *D, const Stmt *Body,
const BlockExpr *blkExpr,
const CheckFallThroughDiagnostics& CD,
AnalysisDeclContext &AC) {
bool ReturnsVoid = false;
bool HasNoReturn = false;
if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
ReturnsVoid = FD->getResultType()->isVoidType();
HasNoReturn = FD->hasAttr<NoReturnAttr>() ||
FD->getType()->getAs<FunctionType>()->getNoReturnAttr();
}
else if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) {
ReturnsVoid = MD->getResultType()->isVoidType();
HasNoReturn = MD->hasAttr<NoReturnAttr>();
}
else if (isa<BlockDecl>(D)) {
QualType BlockTy = blkExpr->getType();
if (const FunctionType *FT =
BlockTy->getPointeeType()->getAs<FunctionType>()) {
if (FT->getResultType()->isVoidType())
ReturnsVoid = true;
if (FT->getNoReturnAttr())
HasNoReturn = true;
}
}
DiagnosticsEngine &Diags = S.getDiagnostics();
// Short circuit for compilation speed.
if (CD.checkDiagnostics(Diags, ReturnsVoid, HasNoReturn))
return;
// FIXME: Function try block
if (const CompoundStmt *Compound = dyn_cast<CompoundStmt>(Body)) {
switch (CheckFallThrough(AC)) {
case UnknownFallThrough:
break;
case MaybeFallThrough:
if (HasNoReturn)
S.Diag(Compound->getRBracLoc(),
CD.diag_MaybeFallThrough_HasNoReturn);
else if (!ReturnsVoid)
S.Diag(Compound->getRBracLoc(),
CD.diag_MaybeFallThrough_ReturnsNonVoid);
break;
case AlwaysFallThrough:
if (HasNoReturn)
S.Diag(Compound->getRBracLoc(),
CD.diag_AlwaysFallThrough_HasNoReturn);
else if (!ReturnsVoid)
S.Diag(Compound->getRBracLoc(),
CD.diag_AlwaysFallThrough_ReturnsNonVoid);
break;
case NeverFallThroughOrReturn:
if (ReturnsVoid && !HasNoReturn && CD.diag_NeverFallThroughOrReturn) {
if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
S.Diag(Compound->getLBracLoc(), CD.diag_NeverFallThroughOrReturn)
<< 0 << FD;
} else if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) {
S.Diag(Compound->getLBracLoc(), CD.diag_NeverFallThroughOrReturn)
<< 1 << MD;
} else {
S.Diag(Compound->getLBracLoc(), CD.diag_NeverFallThroughOrReturn);
}
}
break;
case NeverFallThrough:
break;
}
}
}
//===----------------------------------------------------------------------===//
// -Wuninitialized
//===----------------------------------------------------------------------===//
namespace {
/// ContainsReference - A visitor class to search for references to
/// a particular declaration (the needle) within any evaluated component of an
/// expression (recursively).
class ContainsReference : public EvaluatedExprVisitor<ContainsReference> {
bool FoundReference;
const DeclRefExpr *Needle;
public:
ContainsReference(ASTContext &Context, const DeclRefExpr *Needle)
: EvaluatedExprVisitor<ContainsReference>(Context),
FoundReference(false), Needle(Needle) {}
void VisitExpr(Expr *E) {
// Stop evaluating if we already have a reference.
if (FoundReference)
return;
EvaluatedExprVisitor<ContainsReference>::VisitExpr(E);
}
void VisitDeclRefExpr(DeclRefExpr *E) {
if (E == Needle)
FoundReference = true;
else
EvaluatedExprVisitor<ContainsReference>::VisitDeclRefExpr(E);
}
bool doesContainReference() const { return FoundReference; }
};
}
static bool SuggestInitializationFixit(Sema &S, const VarDecl *VD) {
// Don't issue a fixit if there is already an initializer.
if (VD->getInit())
return false;
// Suggest possible initialization (if any).
QualType VariableTy = VD->getType().getCanonicalType();
const char *Init = S.getFixItZeroInitializerForType(VariableTy);
if (!Init)
return false;
SourceLocation Loc = S.PP.getLocForEndOfToken(VD->getLocEnd());
S.Diag(Loc, diag::note_var_fixit_add_initialization) << VD->getDeclName()
<< FixItHint::CreateInsertion(Loc, Init);
return true;
}
/// DiagnoseUninitializedUse -- Helper function for diagnosing uses of an
/// uninitialized variable. This manages the different forms of diagnostic
/// emitted for particular types of uses. Returns true if the use was diagnosed
/// as a warning. If a pariticular use is one we omit warnings for, returns
/// false.
static bool DiagnoseUninitializedUse(Sema &S, const VarDecl *VD,
const Expr *E, bool isAlwaysUninit,
bool alwaysReportSelfInit = false) {
bool isSelfInit = false;
if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
if (isAlwaysUninit) {
// Inspect the initializer of the variable declaration which is
// being referenced prior to its initialization. We emit
// specialized diagnostics for self-initialization, and we
// specifically avoid warning about self references which take the
// form of:
//
// int x = x;
//
// This is used to indicate to GCC that 'x' is intentionally left
// uninitialized. Proven code paths which access 'x' in
// an uninitialized state after this will still warn.
//
// TODO: Should we suppress maybe-uninitialized warnings for
// variables initialized in this way?
if (const Expr *Initializer = VD->getInit()) {
if (!alwaysReportSelfInit && DRE == Initializer->IgnoreParenImpCasts())
return false;
ContainsReference CR(S.Context, DRE);
CR.Visit(const_cast<Expr*>(Initializer));
isSelfInit = CR.doesContainReference();
}
if (isSelfInit) {
S.Diag(DRE->getLocStart(),
diag::warn_uninit_self_reference_in_init)
<< VD->getDeclName() << VD->getLocation() << DRE->getSourceRange();
} else {
S.Diag(DRE->getLocStart(), diag::warn_uninit_var)
<< VD->getDeclName() << DRE->getSourceRange();
}
} else {
S.Diag(DRE->getLocStart(), diag::warn_maybe_uninit_var)
<< VD->getDeclName() << DRE->getSourceRange();
}
} else {
const BlockExpr *BE = cast<BlockExpr>(E);
S.Diag(BE->getLocStart(),
isAlwaysUninit ? diag::warn_uninit_var_captured_by_block
: diag::warn_maybe_uninit_var_captured_by_block)
<< VD->getDeclName();
}
// Report where the variable was declared when the use wasn't within
// the initializer of that declaration & we didn't already suggest
// an initialization fixit.
if (!isSelfInit && !SuggestInitializationFixit(S, VD))
S.Diag(VD->getLocStart(), diag::note_uninit_var_def)
<< VD->getDeclName();
return true;
}
typedef std::pair<const Expr*, bool> UninitUse;
namespace {
struct SLocSort {
bool operator()(const UninitUse &a, const UninitUse &b) {
SourceLocation aLoc = a.first->getLocStart();
SourceLocation bLoc = b.first->getLocStart();
return aLoc.getRawEncoding() < bLoc.getRawEncoding();
}
};
class UninitValsDiagReporter : public UninitVariablesHandler {
Sema &S;
typedef SmallVector<UninitUse, 2> UsesVec;
typedef llvm::DenseMap<const VarDecl *, std::pair<UsesVec*, bool> > UsesMap;
UsesMap *uses;
public:
UninitValsDiagReporter(Sema &S) : S(S), uses(0) {}
~UninitValsDiagReporter() {
flushDiagnostics();
}
std::pair<UsesVec*, bool> &getUses(const VarDecl *vd) {
if (!uses)
uses = new UsesMap();
UsesMap::mapped_type &V = (*uses)[vd];
UsesVec *&vec = V.first;
if (!vec)
vec = new UsesVec();
return V;
}
void handleUseOfUninitVariable(const Expr *ex, const VarDecl *vd,
bool isAlwaysUninit) {
getUses(vd).first->push_back(std::make_pair(ex, isAlwaysUninit));
}
void handleSelfInit(const VarDecl *vd) {
getUses(vd).second = true;
}
void flushDiagnostics() {
if (!uses)
return;
for (UsesMap::iterator i = uses->begin(), e = uses->end(); i != e; ++i) {
const VarDecl *vd = i->first;
const UsesMap::mapped_type &V = i->second;
UsesVec *vec = V.first;
bool hasSelfInit = V.second;
// Specially handle the case where we have uses of an uninitialized
// variable, but the root cause is an idiomatic self-init. We want
// to report the diagnostic at the self-init since that is the root cause.
if (!vec->empty() && hasSelfInit && hasAlwaysUninitializedUse(vec))
DiagnoseUninitializedUse(S, vd, vd->getInit()->IgnoreParenCasts(),
/* isAlwaysUninit */ true,
/* alwaysReportSelfInit */ true);
else {
// Sort the uses by their SourceLocations. While not strictly
// guaranteed to produce them in line/column order, this will provide
// a stable ordering.
std::sort(vec->begin(), vec->end(), SLocSort());
for (UsesVec::iterator vi = vec->begin(), ve = vec->end(); vi != ve;
++vi) {
if (DiagnoseUninitializedUse(S, vd, vi->first,
/*isAlwaysUninit=*/vi->second))
// Skip further diagnostics for this variable. We try to warn only
// on the first point at which a variable is used uninitialized.
break;
}
}
// Release the uses vector.
delete vec;
}
delete uses;
}
private:
static bool hasAlwaysUninitializedUse(const UsesVec* vec) {
for (UsesVec::const_iterator i = vec->begin(), e = vec->end(); i != e; ++i) {
if (i->second) {
return true;
}
}
return false;
}
};
}
//===----------------------------------------------------------------------===//
// -Wthread-safety
//===----------------------------------------------------------------------===//
namespace clang {
namespace thread_safety {
typedef std::pair<SourceLocation, PartialDiagnostic> DelayedDiag;
typedef llvm::SmallVector<DelayedDiag, 4> DiagList;
struct SortDiagBySourceLocation {
Sema &S;
SortDiagBySourceLocation(Sema &S) : S(S) {}
bool operator()(const DelayedDiag &left, const DelayedDiag &right) {
// Although this call will be slow, this is only called when outputting
// multiple warnings.
return S.getSourceManager().isBeforeInTranslationUnit(left.first,
right.first);
}
};
namespace {
class ThreadSafetyReporter : public clang::thread_safety::ThreadSafetyHandler {
Sema &S;
DiagList Warnings;
SourceLocation FunLocation;
// Helper functions
void warnLockMismatch(unsigned DiagID, Name LockName, SourceLocation Loc) {
// Gracefully handle rare cases when the analysis can't get a more
// precise source location.
if (!Loc.isValid())
Loc = FunLocation;
PartialDiagnostic Warning = S.PDiag(DiagID) << LockName;
Warnings.push_back(DelayedDiag(Loc, Warning));
}
public:
ThreadSafetyReporter(Sema &S, SourceLocation FL)
: S(S), FunLocation(FL) {}
/// \brief Emit all buffered diagnostics in order of sourcelocation.
/// We need to output diagnostics produced while iterating through
/// the lockset in deterministic order, so this function orders diagnostics
/// and outputs them.
void emitDiagnostics() {
SortDiagBySourceLocation SortDiagBySL(S);
sort(Warnings.begin(), Warnings.end(), SortDiagBySL);
for (DiagList::iterator I = Warnings.begin(), E = Warnings.end();
I != E; ++I)
S.Diag(I->first, I->second);
}
void handleInvalidLockExp(SourceLocation Loc) {
PartialDiagnostic Warning = S.PDiag(diag::warn_cannot_resolve_lock) << Loc;
Warnings.push_back(DelayedDiag(Loc, Warning));
}
void handleUnmatchedUnlock(Name LockName, SourceLocation Loc) {
warnLockMismatch(diag::warn_unlock_but_no_lock, LockName, Loc);
}
void handleDoubleLock(Name LockName, SourceLocation Loc) {
warnLockMismatch(diag::warn_double_lock, LockName, Loc);
}
void handleMutexHeldEndOfScope(Name LockName, SourceLocation Loc,
LockErrorKind LEK){
unsigned DiagID = 0;
switch (LEK) {
case LEK_LockedSomePredecessors:
DiagID = diag::warn_lock_at_end_of_scope;
break;
case LEK_LockedSomeLoopIterations:
DiagID = diag::warn_expecting_lock_held_on_loop;
break;
case LEK_LockedAtEndOfFunction:
DiagID = diag::warn_no_unlock;
break;
}
warnLockMismatch(DiagID, LockName, Loc);
}
void handleExclusiveAndShared(Name LockName, SourceLocation Loc1,
SourceLocation Loc2) {
PartialDiagnostic Warning =
S.PDiag(diag::warn_lock_exclusive_and_shared) << LockName;
PartialDiagnostic Note =
S.PDiag(diag::note_lock_exclusive_and_shared) << LockName;
Warnings.push_back(DelayedDiag(Loc1, Warning));
Warnings.push_back(DelayedDiag(Loc2, Note));
}
void handleNoMutexHeld(const NamedDecl *D, ProtectedOperationKind POK,
AccessKind AK, SourceLocation Loc) {
assert((POK == POK_VarAccess || POK == POK_VarDereference)
&& "Only works for variables");
unsigned DiagID = POK == POK_VarAccess?
diag::warn_variable_requires_any_lock:
diag::warn_var_deref_requires_any_lock;
PartialDiagnostic Warning = S.PDiag(DiagID)
<< D->getName() << getLockKindFromAccessKind(AK);
Warnings.push_back(DelayedDiag(Loc, Warning));
}
void handleMutexNotHeld(const NamedDecl *D, ProtectedOperationKind POK,
Name LockName, LockKind LK, SourceLocation Loc) {
unsigned DiagID = 0;
switch (POK) {
case POK_VarAccess:
DiagID = diag::warn_variable_requires_lock;
break;
case POK_VarDereference:
DiagID = diag::warn_var_deref_requires_lock;
break;
case POK_FunctionCall:
DiagID = diag::warn_fun_requires_lock;
break;
}
PartialDiagnostic Warning = S.PDiag(DiagID)
<< D->getName() << LockName << LK;
Warnings.push_back(DelayedDiag(Loc, Warning));
}
void handleFunExcludesLock(Name FunName, Name LockName, SourceLocation Loc) {
PartialDiagnostic Warning =
S.PDiag(diag::warn_fun_excludes_mutex) << FunName << LockName;
Warnings.push_back(DelayedDiag(Loc, Warning));
}
};
}
}
}
//===----------------------------------------------------------------------===//
// AnalysisBasedWarnings - Worker object used by Sema to execute analysis-based
// warnings on a function, method, or block.
//===----------------------------------------------------------------------===//
clang::sema::AnalysisBasedWarnings::Policy::Policy() {
enableCheckFallThrough = 1;
enableCheckUnreachable = 0;
enableThreadSafetyAnalysis = 0;
}
clang::sema::AnalysisBasedWarnings::AnalysisBasedWarnings(Sema &s)
: S(s),
NumFunctionsAnalyzed(0),
NumFunctionsWithBadCFGs(0),
NumCFGBlocks(0),
MaxCFGBlocksPerFunction(0),
NumUninitAnalysisFunctions(0),
NumUninitAnalysisVariables(0),
MaxUninitAnalysisVariablesPerFunction(0),
NumUninitAnalysisBlockVisits(0),
MaxUninitAnalysisBlockVisitsPerFunction(0) {
DiagnosticsEngine &D = S.getDiagnostics();
DefaultPolicy.enableCheckUnreachable = (unsigned)
(D.getDiagnosticLevel(diag::warn_unreachable, SourceLocation()) !=
DiagnosticsEngine::Ignored);
DefaultPolicy.enableThreadSafetyAnalysis = (unsigned)
(D.getDiagnosticLevel(diag::warn_double_lock, SourceLocation()) !=
DiagnosticsEngine::Ignored);
}
static void flushDiagnostics(Sema &S, sema::FunctionScopeInfo *fscope) {
for (SmallVectorImpl<sema::PossiblyUnreachableDiag>::iterator
i = fscope->PossiblyUnreachableDiags.begin(),
e = fscope->PossiblyUnreachableDiags.end();
i != e; ++i) {
const sema::PossiblyUnreachableDiag &D = *i;
S.Diag(D.Loc, D.PD);
}
}
void clang::sema::
AnalysisBasedWarnings::IssueWarnings(sema::AnalysisBasedWarnings::Policy P,
sema::FunctionScopeInfo *fscope,
const Decl *D, const BlockExpr *blkExpr) {
// We avoid doing analysis-based warnings when there are errors for
// two reasons:
// (1) The CFGs often can't be constructed (if the body is invalid), so
// don't bother trying.
// (2) The code already has problems; running the analysis just takes more
// time.
DiagnosticsEngine &Diags = S.getDiagnostics();
// Do not do any analysis for declarations in system headers if we are
// going to just ignore them.
if (Diags.getSuppressSystemWarnings() &&
S.SourceMgr.isInSystemHeader(D->getLocation()))
return;
// For code in dependent contexts, we'll do this at instantiation time.
if (cast<DeclContext>(D)->isDependentContext())
return;
if (Diags.hasErrorOccurred() || Diags.hasFatalErrorOccurred()) {
// Flush out any possibly unreachable diagnostics.
flushDiagnostics(S, fscope);
return;
}
const Stmt *Body = D->getBody();
assert(Body);
AnalysisDeclContext AC(/* AnalysisDeclContextManager */ 0, D, 0);
// Don't generate EH edges for CallExprs as we'd like to avoid the n^2
// explosion for destrutors that can result and the compile time hit.
AC.getCFGBuildOptions().PruneTriviallyFalseEdges = true;
AC.getCFGBuildOptions().AddEHEdges = false;
AC.getCFGBuildOptions().AddInitializers = true;
AC.getCFGBuildOptions().AddImplicitDtors = true;
// Force that certain expressions appear as CFGElements in the CFG. This
// is used to speed up various analyses.
// FIXME: This isn't the right factoring. This is here for initial
// prototyping, but we need a way for analyses to say what expressions they
// expect to always be CFGElements and then fill in the BuildOptions
// appropriately. This is essentially a layering violation.
if (P.enableCheckUnreachable || P.enableThreadSafetyAnalysis) {
// Unreachable code analysis and thread safety require a linearized CFG.
AC.getCFGBuildOptions().setAllAlwaysAdd();
}
else {
AC.getCFGBuildOptions()
.setAlwaysAdd(Stmt::BinaryOperatorClass)
.setAlwaysAdd(Stmt::BlockExprClass)
.setAlwaysAdd(Stmt::CStyleCastExprClass)
.setAlwaysAdd(Stmt::DeclRefExprClass)
.setAlwaysAdd(Stmt::ImplicitCastExprClass)
.setAlwaysAdd(Stmt::UnaryOperatorClass);
}
// Construct the analysis context with the specified CFG build options.
// Emit delayed diagnostics.
if (!fscope->PossiblyUnreachableDiags.empty()) {
bool analyzed = false;
// Register the expressions with the CFGBuilder.
for (SmallVectorImpl<sema::PossiblyUnreachableDiag>::iterator
i = fscope->PossiblyUnreachableDiags.begin(),
e = fscope->PossiblyUnreachableDiags.end();
i != e; ++i) {
if (const Stmt *stmt = i->stmt)
AC.registerForcedBlockExpression(stmt);
}
if (AC.getCFG()) {
analyzed = true;
for (SmallVectorImpl<sema::PossiblyUnreachableDiag>::iterator
i = fscope->PossiblyUnreachableDiags.begin(),
e = fscope->PossiblyUnreachableDiags.end();
i != e; ++i)
{
const sema::PossiblyUnreachableDiag &D = *i;
bool processed = false;
if (const Stmt *stmt = i->stmt) {
const CFGBlock *block = AC.getBlockForRegisteredExpression(stmt);
CFGReverseBlockReachabilityAnalysis *cra =
AC.getCFGReachablityAnalysis();
// FIXME: We should be able to assert that block is non-null, but
// the CFG analysis can skip potentially-evaluated expressions in
// edge cases; see test/Sema/vla-2.c.
if (block && cra) {
// Can this block be reached from the entrance?
if (cra->isReachable(&AC.getCFG()->getEntry(), block))
S.Diag(D.Loc, D.PD);
processed = true;
}
}
if (!processed) {
// Emit the warning anyway if we cannot map to a basic block.
S.Diag(D.Loc, D.PD);
}
}
}
if (!analyzed)
flushDiagnostics(S, fscope);
}
// Warning: check missing 'return'
if (P.enableCheckFallThrough) {
const CheckFallThroughDiagnostics &CD =
(isa<BlockDecl>(D) ? CheckFallThroughDiagnostics::MakeForBlock()
: CheckFallThroughDiagnostics::MakeForFunction(D));
CheckFallThroughForBody(S, D, Body, blkExpr, CD, AC);
}
// Warning: check for unreachable code
if (P.enableCheckUnreachable) {
// Only check for unreachable code on non-template instantiations.
// Different template instantiations can effectively change the control-flow
// and it is very difficult to prove that a snippet of code in a template
// is unreachable for all instantiations.
bool isTemplateInstantiation = false;
if (const FunctionDecl *Function = dyn_cast<FunctionDecl>(D))
isTemplateInstantiation = Function->isTemplateInstantiation();
if (!isTemplateInstantiation)
CheckUnreachable(S, AC);
}
// Check for thread safety violations
if (P.enableThreadSafetyAnalysis) {
SourceLocation FL = AC.getDecl()->getLocation();
thread_safety::ThreadSafetyReporter Reporter(S, FL);
thread_safety::runThreadSafetyAnalysis(AC, Reporter);
Reporter.emitDiagnostics();
}
if (Diags.getDiagnosticLevel(diag::warn_uninit_var, D->getLocStart())
!= DiagnosticsEngine::Ignored ||
Diags.getDiagnosticLevel(diag::warn_maybe_uninit_var, D->getLocStart())
!= DiagnosticsEngine::Ignored) {
if (CFG *cfg = AC.getCFG()) {
UninitValsDiagReporter reporter(S);
UninitVariablesAnalysisStats stats;
std::memset(&stats, 0, sizeof(UninitVariablesAnalysisStats));
runUninitializedVariablesAnalysis(*cast<DeclContext>(D), *cfg, AC,
reporter, stats);
if (S.CollectStats && stats.NumVariablesAnalyzed > 0) {
++NumUninitAnalysisFunctions;
NumUninitAnalysisVariables += stats.NumVariablesAnalyzed;
NumUninitAnalysisBlockVisits += stats.NumBlockVisits;
MaxUninitAnalysisVariablesPerFunction =
std::max(MaxUninitAnalysisVariablesPerFunction,
stats.NumVariablesAnalyzed);
MaxUninitAnalysisBlockVisitsPerFunction =
std::max(MaxUninitAnalysisBlockVisitsPerFunction,
stats.NumBlockVisits);
}
}
}
// Collect statistics about the CFG if it was built.
if (S.CollectStats && AC.isCFGBuilt()) {
++NumFunctionsAnalyzed;
if (CFG *cfg = AC.getCFG()) {
// If we successfully built a CFG for this context, record some more
// detail information about it.
NumCFGBlocks += cfg->getNumBlockIDs();
MaxCFGBlocksPerFunction = std::max(MaxCFGBlocksPerFunction,
cfg->getNumBlockIDs());
} else {
++NumFunctionsWithBadCFGs;
}
}
}
void clang::sema::AnalysisBasedWarnings::PrintStats() const {
llvm::errs() << "\n*** Analysis Based Warnings Stats:\n";
unsigned NumCFGsBuilt = NumFunctionsAnalyzed - NumFunctionsWithBadCFGs;
unsigned AvgCFGBlocksPerFunction =
!NumCFGsBuilt ? 0 : NumCFGBlocks/NumCFGsBuilt;
llvm::errs() << NumFunctionsAnalyzed << " functions analyzed ("
<< NumFunctionsWithBadCFGs << " w/o CFGs).\n"
<< " " << NumCFGBlocks << " CFG blocks built.\n"
<< " " << AvgCFGBlocksPerFunction
<< " average CFG blocks per function.\n"
<< " " << MaxCFGBlocksPerFunction
<< " max CFG blocks per function.\n";
unsigned AvgUninitVariablesPerFunction = !NumUninitAnalysisFunctions ? 0
: NumUninitAnalysisVariables/NumUninitAnalysisFunctions;
unsigned AvgUninitBlockVisitsPerFunction = !NumUninitAnalysisFunctions ? 0
: NumUninitAnalysisBlockVisits/NumUninitAnalysisFunctions;
llvm::errs() << NumUninitAnalysisFunctions
<< " functions analyzed for uninitialiazed variables\n"
<< " " << NumUninitAnalysisVariables << " variables analyzed.\n"
<< " " << AvgUninitVariablesPerFunction
<< " average variables per function.\n"
<< " " << MaxUninitAnalysisVariablesPerFunction
<< " max variables per function.\n"
<< " " << NumUninitAnalysisBlockVisits << " block visits.\n"
<< " " << AvgUninitBlockVisitsPerFunction
<< " average block visits per function.\n"
<< " " << MaxUninitAnalysisBlockVisitsPerFunction
<< " max block visits per function.\n";
}
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