void WhereInvariant::GetHeapBits(CheckerFrame *write_frame,
Exp *write_csu, Exp *base_csu,
Bit **base_bit, GuardBitVector *res)
{
BlockMemory *mcfg = write_frame->Memory();
Exp *old_lval = NULL;
if (m_csu) {
Variable *this_var = Variable::Make(NULL, VK_This, NULL, 0, NULL);
Exp *old_this = Exp::MakeVar(this_var);
old_lval = Exp::MakeDrf(old_this);
}
Bit *exit_bit = TranslateHeapBit(old_lval, write_csu, true, m_bit);
Assert(exit_bit);
if (old_lval)
old_lval->DecRef();
// TODO: using this to get the base bit for an invariant is fairly
// hacked up, but for now we can't do this correctly as the base bit
// needs to be relative to the CFG exit point, not the point where
// any writes occur at. for now just get the displayable point for
// the base CSU, and hope that means the same thing at exit as at
// the point of the write.
Bit *new_bit = BitConvertExitClobber(m_bit);
if (base_csu) {
*base_bit = BitReplaceExp(new_bit, old_lval, base_csu);
new_bit->DecRef();
}
else {
*base_bit = new_bit;
}
GuardBitVector base_res;
PPoint exit_point = mcfg->GetCFG()->GetExitPoint();
mcfg->TranslateBit(TRK_Exit, exit_point, exit_bit, &base_res);
exit_bit->DecRef();
RemoveValBit(write_frame->Id(), write_frame->Memory(), base_res, res);
}
void Visit(Exp *exp)
{
if (ExpFld *nexp = exp->IfFld()) {
// pick up any type invariants from the host type.
String *csu_name = nexp->GetField()->GetCSUType()->GetCSUName();
Vector<BlockCFG*> *annot_list = CompAnnotCache.Lookup(csu_name);
for (size_t ind = 0; annot_list && ind < annot_list->Size(); ind++) {
BlockCFG *annot_cfg = annot_list->At(ind);
Assert(annot_cfg->GetAnnotationKind() == AK_Invariant ||
annot_cfg->GetAnnotationKind() == AK_InvariantAssume);
BlockId *id = annot_cfg->GetId();
Bit *bit = BlockMemory::GetAnnotationBit(annot_cfg);
if (!bit) continue;
// get the *this expression. we'll replace this with the actual CSU
// lvalue to get the assumed bit.
id->IncRef();
Variable *this_var = Variable::Make(id, VK_This, NULL, 0, NULL);
Exp *this_exp = Exp::MakeVar(this_var);
Exp *this_drf = Exp::MakeDrf(this_exp);
Exp *target = nexp->GetTarget();
GuardExpVector lval_res;
if (mcfg) {
mcfg->TranslateExp(TRK_Point, point, target, &lval_res);
}
else {
target->IncRef();
lval_res.PushBack(GuardExp(target, Bit::MakeConstant(true)));
}
for (size_t lind = 0; lind < lval_res.Size(); lind++) {
// ignore the guard component of the result here. this means that
// accessing a field of a value means related invariants hold for
// the value along all paths. which is normally right, except when
// the value is the result of a cast, and could have a different type
// along other paths. TODO: sort this out.
const GuardExp &gs = lval_res[lind];
Bit *new_bit = BitReplaceExp(bit, this_drf, gs.exp);
new_bit->MoveRef(NULL, assume_list);
annot_cfg->IncRef(assume_list);
AssumeInfo info;
info.annot = annot_cfg;
info.point = 0;
info.bit = new_bit;
assume_list->PushBack(info);
}
this_drf->DecRef();
}
CompAnnotCache.Release(csu_name);
}
if (ExpVar *nexp = exp->IfVar()) {
if (nexp->GetVariable()->Kind() == VK_Glob) {
String *var_name = nexp->GetVariable()->GetName();
Vector<BlockCFG*> *annot_list = InitAnnotCache.Lookup(var_name);
for (size_t ind = 0; annot_list && ind < annot_list->Size(); ind++) {
BlockCFG *annot_cfg = annot_list->At(ind);
Assert(annot_cfg->GetAnnotationKind() == AK_Invariant ||
annot_cfg->GetAnnotationKind() == AK_InvariantAssume);
Bit *bit = BlockMemory::GetAnnotationBit(annot_cfg);
if (!bit) continue;
bit->IncRef(assume_list);
annot_cfg->IncRef(assume_list);
AssumeInfo info;
info.annot = annot_cfg;
info.point = 0;
info.bit = bit;
assume_list->PushBack(info);
}
InitAnnotCache.Release(var_name);
}
}
}
void InferSummaries(const Vector<BlockSummary*> &summary_list)
{
static BaseTimer infer_timer("infer_summaries");
Timer _timer(&infer_timer);
if (summary_list.Empty())
return;
Variable *function = summary_list[0]->GetId()->BaseVar();
Vector<BlockCFG*> *annot_list = BodyAnnotCache.Lookup(function->GetName());
// all traces which might refer to the result of pointer arithmetic.
Vector<Exp*> arithmetic_list;
ArithmeticEscape escape(function, arithmetic_list);
// initial pass over the CFGs to get traces used in pointer arithmetic.
for (size_t ind = 0; ind < summary_list.Size(); ind++) {
BlockSummary *sum = summary_list[ind];
BlockCFG *cfg = sum->GetMemory()->GetCFG();
for (size_t eind = 0; eind < cfg->GetEdgeCount(); eind++) {
PEdge *edge = cfg->GetEdge(eind);
if (PEdgeAssign *assign_edge = edge->IfAssign()) {
Exp *left = assign_edge->GetLeftSide();
Exp *right = assign_edge->GetRightSide();
ProcessArithmeticAssign(&escape, cfg->GetId(), left, right);
}
}
}
for (size_t ind = 0; ind < summary_list.Size(); ind++) {
BlockSummary *sum = summary_list[ind];
BlockMemory *mcfg = sum->GetMemory();
BlockCFG *cfg = mcfg->GetCFG();
// accumulate all the assertions at points in the CFG.
Vector<AssertInfo> asserts;
// add assertions at function exit for any postconditions.
if (cfg->GetId()->Kind() == B_Function) {
for (size_t aind = 0; annot_list && aind < annot_list->Size(); aind++) {
BlockCFG *annot_cfg = annot_list->At(aind);
if (annot_cfg->GetAnnotationKind() != AK_Postcondition)
continue;
if (Bit *bit = BlockMemory::GetAnnotationBit(annot_cfg)) {
AssertInfo info;
info.kind = ASK_Annotation;
info.cls = ASC_Check;
info.point = cfg->GetExitPoint();
info.bit = bit;
asserts.PushBack(info);
}
}
}
// add assertions for any point annotations within the CFG.
for (size_t pind = 0; pind < cfg->GetPointAnnotationCount(); pind++) {
PointAnnotation pann = cfg->GetPointAnnotation(pind);
BlockCFG *annot_cfg = GetAnnotationCFG(pann.annot);
if (!annot_cfg) continue;
if (annot_cfg->GetAnnotationKind() != AK_Assert)
continue;
if (Bit *bit = BlockMemory::GetAnnotationBit(annot_cfg)) {
AssertInfo info;
info.kind = ASK_Annotation;
info.cls = ASC_Check;
info.point = pann.point;
info.bit = bit;
asserts.PushBack(info);
}
}
for (size_t eind = 0; eind < cfg->GetEdgeCount(); eind++) {
PEdge *edge = cfg->GetEdge(eind);
PPoint point = edge->GetSource();
if (PEdgeAnnotation *nedge = edge->IfAnnotation()) {
// add an assertion for this annotation if it not an assume.
BlockCFG *annot_cfg = GetAnnotationCFG(nedge->GetAnnotationId());
if (!annot_cfg) continue;
if (annot_cfg->GetAnnotationKind() != AK_Assert &&
annot_cfg->GetAnnotationKind() != AK_AssertRuntime) {
continue;
}
if (Bit *bit = BlockMemory::GetAnnotationBit(annot_cfg)) {
AssertInfo info;
info.kind = (annot_cfg->GetAnnotationKind() == AK_Assert)
? ASK_Annotation : ASK_AnnotationRuntime;
info.cls = ASC_Check;
info.point = point;
info.bit = bit;
asserts.PushBack(info);
}
}
// add assertions for any invariants affected by a write.
Exp *left = NULL;
if (PEdgeAssign *nedge = edge->IfAssign())
left = nedge->GetLeftSide();
if (PEdgeCall *nedge = edge->IfCall())
left = nedge->GetReturnValue();
// for now our detection of affected invariants is pretty crude;
// writes to fields can affect type invariants on the field's type
// which use that field, and writes to global variables can affect
// invariants on that global. TODO: pin this down once we draw a
// precise line between which invariants can and can't be checked.
if (left && left->IsFld()) {
ExpFld *nleft = left->AsFld();
String *csu_name = nleft->GetField()->GetCSUType()->GetCSUName();
Vector<BlockCFG*> *comp_annot_list = CompAnnotCache.Lookup(csu_name);
for (size_t aind = 0; comp_annot_list &&
aind < comp_annot_list->Size(); aind++) {
BlockCFG *annot_cfg = comp_annot_list->At(aind);
if (annot_cfg->GetAnnotationKind() != AK_Invariant)
continue;
Bit *bit = BlockMemory::GetAnnotationBit(annot_cfg);
if (!bit) continue;
Vector<Exp*> lval_list;
LvalListVisitor visitor(&lval_list);
bit->DoVisit(&visitor);
bool uses_field = false;
for (size_t ind = 0; ind < lval_list.Size(); ind++) {
if (ExpFld *lval = lval_list[ind]->IfFld()) {
if (lval->GetField() == nleft->GetField())
uses_field = true;
}
}
if (uses_field) {
// this is a type invariant which uses the field being written
// as an lvalue. we need to assert this write preserves
// the invariant.
BlockId *id = annot_cfg->GetId();
Variable *this_var = Variable::Make(id, VK_This, NULL, 0, NULL);
Exp *this_exp = Exp::MakeVar(this_var);
Exp *this_drf = Exp::MakeDrf(this_exp);
Bit *new_bit = BitReplaceExp(bit, this_drf, nleft->GetTarget());
AssertInfo info;
info.kind = ASK_Invariant;
info.cls = ASC_Check;
info.point = point;
info.bit = new_bit;
asserts.PushBack(info);
}
}
CompAnnotCache.Release(csu_name);
}
if (left && left->IsVar()) {
Variable *var = left->AsVar()->GetVariable();
if (var->Kind() == VK_Glob) {
Vector<BlockCFG*> *glob_annot_list =
InitAnnotCache.Lookup(var->GetName());
for (size_t aind = 0; glob_annot_list &&
aind < glob_annot_list->Size(); aind++) {
BlockCFG *annot_cfg = glob_annot_list->At(aind);
Bit *bit = BlockMemory::GetAnnotationBit(annot_cfg);
if (!bit) continue;
AssertInfo info;
info.kind = ASK_Invariant;
info.cls = ASC_Check;
info.point = point;
info.bit = bit;
asserts.PushBack(info);
}
InitAnnotCache.Release(var->GetName());
}
}
if (PEdgeCall *nedge = edge->IfCall()) {
// add assertions for any callee preconditions.
// pull preconditions from both direct and indirect calls.
Vector<Variable*> callee_names;
if (Variable *callee = nedge->GetDirectFunction()) {
callee_names.PushBack(callee);
}
else {
CallEdgeSet *callees = CalleeCache.Lookup(function);
if (callees) {
for (size_t cind = 0; cind < callees->GetEdgeCount(); cind++) {
const CallEdge &edge = callees->GetEdge(cind);
if (edge.where.id == cfg->GetId() && edge.where.point == point)
callee_names.PushBack(edge.callee);
}
}
// CalleeCache release is below.
}
for (size_t cind = 0; cind < callee_names.Size(); cind++) {
String *callee = callee_names[cind]->GetName();
Vector<BlockCFG*> *call_annot_list = BodyAnnotCache.Lookup(callee);
for (size_t aind = 0;
call_annot_list && aind < call_annot_list->Size(); aind++) {
BlockCFG *annot_cfg = call_annot_list->At(aind);
if (annot_cfg->GetAnnotationKind() != AK_Precondition)
continue;
if (Bit *bit = BlockMemory::GetAnnotationBit(annot_cfg)) {
ConvertCallsiteMapper mapper(cfg, point, false);
Bit *caller_bit = bit->DoMap(&mapper);
if (!caller_bit)
continue;
AssertInfo info;
info.kind = ASK_Annotation;
info.cls = ASC_Check;
info.point = point;
info.bit = caller_bit;
asserts.PushBack(info);
}
}
BodyAnnotCache.Release(callee);
}
if (!nedge->GetDirectFunction())
CalleeCache.Release(function);
}
BufferScanVisitor write_visitor(asserts, arithmetic_list, point, true);
BufferScanVisitor read_visitor(asserts, arithmetic_list, point, false);
IntegerScanVisitor integer_visitor(asserts, point);
GCScanVisitor gcsafe_visitor(asserts, point);
// only look at the written lvalues for the write visitor.
if (PEdgeAssign *assign = edge->IfAssign())
write_visitor.Visit(assign->GetLeftSide());
if (PEdgeCall *call = edge->IfCall()) {
if (Exp *returned = call->GetReturnValue())
write_visitor.Visit(returned);
}
edge->DoVisit(&read_visitor);
// disable integer overflow visitor for now.
// edge->DoVisit(&integer_visitor);
edge->DoVisit(&gcsafe_visitor);
}
if (cfg->GetId()->Kind() == B_Function) {
BlockModset *modset = GetBlockModset(cfg->GetId());
if (modset->CanGC()) {
AssertInfo info;
info.kind = ASK_CanGC;
info.cls = ASC_Check;
info.point = cfg->GetExitPoint();
String *name = cfg->GetId()->BaseVar()->GetName();
Variable *var = Variable::Make(NULL, VK_Glob, name, 0, name);
Exp *varexp = Exp::MakeVar(var);
Exp *gcsafe = Exp::MakeGCSafe(varexp, false);
info.bit = Bit::MakeVar(gcsafe);
asserts.PushBack(info);
}
}
MarkRedundantAssertions(mcfg, asserts);
// move the finished assertion list into the summary.
for (size_t ind = 0; ind < asserts.Size(); ind++) {
const AssertInfo &info = asserts[ind];
sum->AddAssert(info.kind, info.cls, info.point, info.bit);
}
}
// infer delta and termination invariants for all summaries.
for (size_t ind = 0; ind < summary_list.Size(); ind++)
InferInvariants(summary_list[ind], arithmetic_list);
BodyAnnotCache.Release(function->GetName());
}
