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//== Environment.cpp - Map from Stmt* to Locations/Values -------*- C++ -*--==//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defined the Environment and EnvironmentManager classes.
//
//===----------------------------------------------------------------------===//
#include "clang/AST/ExprCXX.h"
#include "clang/AST/ExprObjC.h"
#include "clang/Analysis/AnalysisDeclContext.h"
#include "clang/Analysis/CFG.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
#include "llvm/Support/raw_ostream.h"
using namespace clang;
using namespace ento;
static const Expr *ignoreTransparentExprs(const Expr *E) {
E = E->IgnoreParens();
switch (E->getStmtClass()) {
case Stmt::OpaqueValueExprClass:
E = cast<OpaqueValueExpr>(E)->getSourceExpr();
break;
case Stmt::ExprWithCleanupsClass:
E = cast<ExprWithCleanups>(E)->getSubExpr();
break;
case Stmt::CXXBindTemporaryExprClass:
E = cast<CXXBindTemporaryExpr>(E)->getSubExpr();
break;
case Stmt::SubstNonTypeTemplateParmExprClass:
E = cast<SubstNonTypeTemplateParmExpr>(E)->getReplacement();
break;
default:
// This is the base case: we can't look through more than we already have.
return E;
}
return ignoreTransparentExprs(E);
}
static const Stmt *ignoreTransparentExprs(const Stmt *S) {
if (const Expr *E = dyn_cast<Expr>(S))
return ignoreTransparentExprs(E);
return S;
}
EnvironmentEntry::EnvironmentEntry(const Stmt *S, const LocationContext *L)
: std::pair<const Stmt *,
const StackFrameContext *>(ignoreTransparentExprs(S),
L ? L->getCurrentStackFrame()
: nullptr) {}
SVal Environment::lookupExpr(const EnvironmentEntry &E) const {
const SVal* X = ExprBindings.lookup(E);
if (X) {
SVal V = *X;
return V;
}
return UnknownVal();
}
SVal Environment::getSVal(const EnvironmentEntry &Entry,
SValBuilder& svalBuilder) const {
const Stmt *S = Entry.getStmt();
const LocationContext *LCtx = Entry.getLocationContext();
switch (S->getStmtClass()) {
case Stmt::CXXBindTemporaryExprClass:
case Stmt::ExprWithCleanupsClass:
case Stmt::GenericSelectionExprClass:
case Stmt::OpaqueValueExprClass:
case Stmt::ParenExprClass:
case Stmt::SubstNonTypeTemplateParmExprClass:
llvm_unreachable("Should have been handled by ignoreTransparentExprs");
case Stmt::AddrLabelExprClass:
case Stmt::CharacterLiteralClass:
case Stmt::CXXBoolLiteralExprClass:
case Stmt::CXXScalarValueInitExprClass:
case Stmt::ImplicitValueInitExprClass:
case Stmt::IntegerLiteralClass:
case Stmt::ObjCBoolLiteralExprClass:
case Stmt::CXXNullPtrLiteralExprClass:
case Stmt::ObjCStringLiteralClass:
case Stmt::StringLiteralClass:
case Stmt::TypeTraitExprClass:
// Known constants; defer to SValBuilder.
return svalBuilder.getConstantVal(cast<Expr>(S)).getValue();
case Stmt::ReturnStmtClass: {
const ReturnStmt *RS = cast<ReturnStmt>(S);
if (const Expr *RE = RS->getRetValue())
return getSVal(EnvironmentEntry(RE, LCtx), svalBuilder);
return UndefinedVal();
}
// Handle all other Stmt* using a lookup.
default:
return lookupExpr(EnvironmentEntry(S, LCtx));
}
}
Environment EnvironmentManager::bindExpr(Environment Env,
const EnvironmentEntry &E,
SVal V,
bool Invalidate) {
if (V.isUnknown()) {
if (Invalidate)
return Environment(F.remove(Env.ExprBindings, E));
else
return Env;
}
return Environment(F.add(Env.ExprBindings, E, V));
}
namespace {
class MarkLiveCallback final : public SymbolVisitor {
SymbolReaper &SymReaper;
public:
MarkLiveCallback(SymbolReaper &symreaper) : SymReaper(symreaper) {}
bool VisitSymbol(SymbolRef sym) override {
SymReaper.markLive(sym);
return true;
}
bool VisitMemRegion(const MemRegion *R) override {
SymReaper.markLive(R);
return true;
}
};
} // end anonymous namespace
// removeDeadBindings:
// - Remove subexpression bindings.
// - Remove dead block expression bindings.
// - Keep live block expression bindings:
// - Mark their reachable symbols live in SymbolReaper,
// see ScanReachableSymbols.
// - Mark the region in DRoots if the binding is a loc::MemRegionVal.
Environment
EnvironmentManager::removeDeadBindings(Environment Env,
SymbolReaper &SymReaper,
ProgramStateRef ST) {
// We construct a new Environment object entirely, as this is cheaper than
// individually removing all the subexpression bindings (which will greatly
// outnumber block-level expression bindings).
Environment NewEnv = getInitialEnvironment();
MarkLiveCallback CB(SymReaper);
ScanReachableSymbols RSScaner(ST, CB);
llvm::ImmutableMapRef<EnvironmentEntry,SVal>
EBMapRef(NewEnv.ExprBindings.getRootWithoutRetain(),
F.getTreeFactory());
// Iterate over the block-expr bindings.
for (Environment::iterator I = Env.begin(), E = Env.end();
I != E; ++I) {
const EnvironmentEntry &BlkExpr = I.getKey();
const SVal &X = I.getData();
if (SymReaper.isLive(BlkExpr.getStmt(), BlkExpr.getLocationContext())) {
// Copy the binding to the new map.
EBMapRef = EBMapRef.add(BlkExpr, X);
// Mark all symbols in the block expr's value live.
RSScaner.scan(X);
continue;
} else {
SymExpr::symbol_iterator SI = X.symbol_begin(), SE = X.symbol_end();
for (; SI != SE; ++SI)
SymReaper.maybeDead(*SI);
}
}
NewEnv.ExprBindings = EBMapRef.asImmutableMap();
return NewEnv;
}
void Environment::print(raw_ostream &Out, const char *NL,
const char *Sep) const {
bool isFirst = true;
for (Environment::iterator I = begin(), E = end(); I != E; ++I) {
const EnvironmentEntry &En = I.getKey();
if (isFirst) {
Out << NL << NL
<< "Expressions:"
<< NL;
isFirst = false;
} else {
Out << NL;
}
const Stmt *S = En.getStmt();
assert(S != nullptr && "Expected non-null Stmt");
Out << " (" << (const void*) En.getLocationContext() << ','
<< (const void*) S << ") ";
LangOptions LO; // FIXME.
S->printPretty(Out, nullptr, PrintingPolicy(LO));
Out << " : " << I.getData();
}
}
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