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());
}
void GetMatchingHeapWrites(const EscapeAccess &heap_write,
Vector<HeapWriteInfo> *writes)
{
BlockId *id = heap_write.where.id;
BlockMemory *mcfg = GetBlockMemory(id);
if (mcfg == NULL) {
logout << "WARNING: Missing memory: '" << id << "'" << endl;
return;
}
BlockCFG *cfg = mcfg->GetCFG();
// for incremental analysis, make sure the write CFG uses the right version.
// as for checking callers, if the CFG has changed but the new one still
// has a matching write, we will see an escape access for the new CFG.
if (cfg->GetVersion() != heap_write.where.version) {
if (checker_verbose.IsSpecified())
logout << "CHECK: Write is an older version: "
<< heap_write.where.id << ": "
<< heap_write.where.version << endl;
mcfg->DecRef();
return;
}
PPoint point = heap_write.where.point;
PPoint exit_point = mcfg->GetCFG()->GetExitPoint();
// find a point-relative lvalue written at the write point with
// the sanitized representation from the heap_write trace.
// TODO: we only match against direct assignments in the CFG for now,
// ignoring structural copies (which are simple recursive writes).
PEdge *edge = cfg->GetSingleOutgoingEdge(point);
Exp *point_lval = NULL;
if (PEdgeAssign *nedge = edge->IfAssign())
point_lval = nedge->GetLeftSide();
else if (PEdgeCall *nedge = edge->IfCall())
point_lval = nedge->GetReturnValue();
bool lval_matches = false;
if (point_lval) {
if (Exp *new_point_lval = Trace::SanitizeExp(point_lval)) {
lval_matches = (new_point_lval == heap_write.target->GetValue());
new_point_lval->DecRef();
}
}
if (!lval_matches) {
mcfg->DecRef();
return;
}
// it would be nice to remove Val() expressions from this list, but we can't
// do that as lvalues in memory assignments can contain Val and we want to
// see the effects of those assignments. TODO: fix.
GuardExpVector lval_res;
mcfg->TranslateExp(TRK_Point, point, point_lval, &lval_res);
for (size_t ind = 0; ind < lval_res.Size(); ind++) {
const GuardExp &lv = lval_res[ind];
HeapWriteInfo info;
info.mcfg = mcfg;
info.lval = lv.exp;
info.base_lval = point_lval;
// look for a condition where the lvalue is not written.
GuardExpVector exit_vals;
info.mcfg->GetValComplete(info.lval, NULL, exit_point, &exit_vals);
for (size_t ind = 0; ind < exit_vals.Size(); ind++) {
const GuardExp &val = exit_vals[ind];
// exclude cases where the lvalue refers to its value at block entry.
if (ExpDrf *nval = val.exp->IfDrf()) {
if (nval->GetTarget() == info.lval)
info.exclude.PushBack(val.guard);
}
}
if (!writes->Contains(info)) {
info.mcfg->IncRef(writes);
info.lval->IncRef(writes);
info.base_lval->IncRef(writes);
IncRefVector<Bit>(info.exclude, writes);
writes->PushBack(info);
}
}
mcfg->DecRef();
}
Where* CheckerPropagate::TryPropagate(Bit *bit, Exp *lval)
{
BlockMemory *mcfg = m_frame->Memory();
TypeCSU *csu = NULL;
Exp *csu_lval = NULL;
if (UseHeapExp(lval, &csu, &csu_lval)) {
// do the heap propagation unless we are trying to push heap data
// up into the caller.
if (!m_prefer_precondition ||
!UseCallerExp(lval, m_frame->Kind() == B_Function) ||
(m_frame->Kind() == B_Loop && !mcfg->IsExpPreserved(lval))) {
Where *res = WhereInvariant::Make(csu, csu_lval, bit);
if (res)
return res;
// fall through, we might still be able to treat this as a precondition.
}
}
if (UseCallerExp(lval, m_frame->Kind() == B_Function))
return WherePrecondition::Make(m_frame->Memory(), bit);
if (PPoint point = UseCalleeExp(lval)) {
// fail propagation if this is from a later callee than the point
// this propagation occurs at. this can come up when generating
// sufficient conditions.
if (point > m_point || (point == m_point && !m_allow_point))
return NULL;
// cutoff propagation if the buffer came from a primitive memory
// allocator. if we find a sufficient condition that does not
// mention the allocator we could continue propagation.
PEdge *edge = mcfg->GetCFG()->GetSingleOutgoingEdge(point);
PEdgeCall *edge_call = edge->IfCall();
Variable *callee = edge_call ? edge_call->GetDirectFunction() : NULL;
Exp *callee_base;
Exp *callee_size;
if (callee && GetAllocationFunction(callee, &callee_base, &callee_size)) {
callee_base->DecRef();
callee_size->DecRef();
if (lval->IsBound())
lval = lval->GetLvalTarget();
// ignore this if it refers to fields or other structures
// in the result of the allocation. this data is either
// uninitialized or zeroed, either way we don't care.
if (ExpClobber *nlval = lval->IfClobber()) {
Exp *callee_lval = nlval->GetCallee();
Exp *callee_target = NULL;
if (nlval->GetValueKind() == NULL) {
callee_target = callee_lval;
}
else {
// skip the first dereference. for terminators we still depend on
// the initial contents of the allocated buffer.
if (ExpExit *ncallee = callee_lval->IfExit())
callee_target = ncallee->GetTarget();
}
if (callee_target) {
while (callee_target->IsFld())
callee_target = callee_target->GetLvalTarget();
if (callee_target->IsExit())
return new WhereNone(RK_None);
}
}
// watch for accessing indexes of a buffer returned via the allocator,
// which currently aren't mapped back into the callee correctly.
// TODO: fix hack.
if (lval->IsDrf() && lval->GetLvalTarget()->IsIndex())
return new WhereNone(RK_None);
return new WhereNone(RK_Finished);
}
if (callee && IsCutoffFunction(callee))
return new WhereNone(RK_Finished);
return WherePostcondition::Make(m_frame, point, bit);
}
return NULL;
}
