CFLAndersAAResult::FunctionInfo::FunctionInfo(const ReachabilitySet &ReachSet,
AliasAttrMap AMap) {
// Populate AttrMap
for (const auto &Mapping : AMap.mappings()) {
auto IVal = Mapping.first;
// AttrMap only cares about top-level values
if (IVal.DerefLevel == 0)
AttrMap[IVal.Val] = Mapping.second;
}
// Populate AliasMap
for (const auto &OuterMapping : ReachSet.value_mappings()) {
// AliasMap only cares about top-level values
if (OuterMapping.first.DerefLevel > 0)
continue;
auto Val = OuterMapping.first.Val;
auto &AliasList = AliasMap[Val];
for (const auto &InnerMapping : OuterMapping.second) {
// Again, AliasMap only cares about top-level values
if (InnerMapping.first.DerefLevel == 0)
AliasList.push_back(InnerMapping.first.Val);
}
// Sort AliasList for faster lookup
std::sort(AliasList.begin(), AliasList.end(), std::less<const Value *>());
}
// TODO: Populate function summary here
}
static void
populateAliasMap(DenseMap<const Value *, std::vector<OffsetValue>> &AliasMap,
const ReachabilitySet &ReachSet) {
for (const auto &OuterMapping : ReachSet.value_mappings()) {
// AliasMap only cares about top-level values
if (OuterMapping.first.DerefLevel > 0)
continue;
auto Val = OuterMapping.first.Val;
auto &AliasList = AliasMap[Val];
for (const auto &InnerMapping : OuterMapping.second) {
// Again, AliasMap only cares about top-level values
if (InnerMapping.first.DerefLevel == 0)
AliasList.push_back(OffsetValue{InnerMapping.first.Val, UnknownOffset});
}
// Sort AliasList for faster lookup
llvm::sort(AliasList.begin(), AliasList.end());
}
}
static void populateExternalRelations(
SmallVectorImpl<ExternalRelation> &ExtRelations, const Function &Fn,
const SmallVectorImpl<Value *> &RetVals, const ReachabilitySet &ReachSet) {
// If a function only returns one of its argument X, then X will be both an
// argument and a return value at the same time. This is an edge case that
// needs special handling here.
for (const auto &Arg : Fn.args()) {
if (is_contained(RetVals, &Arg)) {
auto ArgVal = InterfaceValue{Arg.getArgNo() + 1, 0};
auto RetVal = InterfaceValue{0, 0};
ExtRelations.push_back(ExternalRelation{ArgVal, RetVal, 0});
}
}
// Below is the core summary construction logic.
// A naive solution of adding only the value aliases that are parameters or
// return values in ReachSet to the summary won't work: It is possible that a
// parameter P is written into an intermediate value I, and the function
// subsequently returns *I. In that case, *I is does not value alias anything
// in ReachSet, and the naive solution will miss a summary edge from (P, 1) to
// (I, 1).
// To account for the aforementioned case, we need to check each non-parameter
// and non-return value for the possibility of acting as an intermediate.
// 'ValueMap' here records, for each value, which InterfaceValues read from or
// write into it. If both the read list and the write list of a given value
// are non-empty, we know that a particular value is an intermidate and we
// need to add summary edges from the writes to the reads.
DenseMap<Value *, ValueSummary> ValueMap;
for (const auto &OuterMapping : ReachSet.value_mappings()) {
if (auto Dst = getInterfaceValue(OuterMapping.first, RetVals)) {
for (const auto &InnerMapping : OuterMapping.second) {
// If Src is a param/return value, we get a same-level assignment.
if (auto Src = getInterfaceValue(InnerMapping.first, RetVals)) {
// This may happen if both Dst and Src are return values
if (*Dst == *Src)
continue;
if (hasReadOnlyState(InnerMapping.second))
ExtRelations.push_back(ExternalRelation{*Dst, *Src, UnknownOffset});
// No need to check for WriteOnly state, since ReachSet is symmetric
} else {
// If Src is not a param/return, add it to ValueMap
auto SrcIVal = InnerMapping.first;
if (hasReadOnlyState(InnerMapping.second))
ValueMap[SrcIVal.Val].FromRecords.push_back(
ValueSummary::Record{*Dst, SrcIVal.DerefLevel});
if (hasWriteOnlyState(InnerMapping.second))
ValueMap[SrcIVal.Val].ToRecords.push_back(
ValueSummary::Record{*Dst, SrcIVal.DerefLevel});
}
}
}
}
for (const auto &Mapping : ValueMap) {
for (const auto &FromRecord : Mapping.second.FromRecords) {
for (const auto &ToRecord : Mapping.second.ToRecords) {
auto ToLevel = ToRecord.DerefLevel;
auto FromLevel = FromRecord.DerefLevel;
// Same-level assignments should have already been processed by now
if (ToLevel == FromLevel)
continue;
auto SrcIndex = FromRecord.IValue.Index;
auto SrcLevel = FromRecord.IValue.DerefLevel;
auto DstIndex = ToRecord.IValue.Index;
auto DstLevel = ToRecord.IValue.DerefLevel;
if (ToLevel > FromLevel)
SrcLevel += ToLevel - FromLevel;
else
DstLevel += FromLevel - ToLevel;
ExtRelations.push_back(ExternalRelation{
InterfaceValue{SrcIndex, SrcLevel},
InterfaceValue{DstIndex, DstLevel}, UnknownOffset});
}
}
}
// Remove duplicates in ExtRelations
llvm::sort(ExtRelations.begin(), ExtRelations.end());
ExtRelations.erase(std::unique(ExtRelations.begin(), ExtRelations.end()),
ExtRelations.end());
}
