[CFLAA] Add attributes handling for CFLAnders.
This patch adds proper handling of stratified attributes into our anders-style CFLAA implementation. It also comes bundled with more CFLAnders tests. :) Patch by Jia Chen. Differential Revision: https://reviews.llvm.org/D22325 llvm-svn: 275604
This commit is contained in:
George Burgess IV
parent
62fba48e0f
commit
22682e293b
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@ -141,6 +141,38 @@ public:
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}
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};
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// We use AliasAttrMap to keep track of the AliasAttr of each node.
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class AliasAttrMap {
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typedef DenseMap<InstantiatedValue, AliasAttrs> MapType;
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MapType AttrMap;
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public:
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typedef MapType::const_iterator const_iterator;
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bool add(InstantiatedValue V, AliasAttrs Attr) {
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if (Attr.none())
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return false;
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auto &OldAttr = AttrMap[V];
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auto NewAttr = OldAttr | Attr;
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if (OldAttr == NewAttr)
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return false;
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OldAttr = NewAttr;
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return true;
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}
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AliasAttrs getAttrs(InstantiatedValue V) const {
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AliasAttrs Attr;
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auto Itr = AttrMap.find(V);
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if (Itr != AttrMap.end())
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Attr = Itr->second;
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return Attr;
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}
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iterator_range<const_iterator> mappings() const {
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return make_range<const_iterator>(AttrMap.begin(), AttrMap.end());
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}
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};
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struct WorkListItem {
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InstantiatedValue From;
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InstantiatedValue To;
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@ -155,17 +187,33 @@ class CFLAndersAAResult::FunctionInfo {
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/// AliasMap[a] but not vice versa.
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DenseMap<const Value *, std::vector<const Value *>> AliasMap;
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/// Map a value to its corresponding AliasAttrs
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DenseMap<const Value *, AliasAttrs> AttrMap;
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/// Summary of externally visible effects.
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AliasSummary Summary;
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AliasAttrs getAttrs(const Value *) const;
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public:
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FunctionInfo(const ReachabilitySet &);
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FunctionInfo(const ReachabilitySet &, AliasAttrMap);
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bool mayAlias(const Value *LHS, const Value *RHS) const;
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const AliasSummary &getAliasSummary() const { return Summary; }
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};
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CFLAndersAAResult::FunctionInfo::FunctionInfo(const ReachabilitySet &ReachSet) {
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CFLAndersAAResult::FunctionInfo::FunctionInfo(const ReachabilitySet &ReachSet,
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AliasAttrMap AMap) {
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// Populate AttrMap
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for (const auto &Mapping : AMap.mappings()) {
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auto IVal = Mapping.first;
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// AttrMap only cares about top-level values
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if (IVal.DerefLevel == 0)
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AttrMap[IVal.Val] = Mapping.second;
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}
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// Populate AliasMap
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for (const auto &OuterMapping : ReachSet.value_mappings()) {
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// AliasMap only cares about top-level values
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if (OuterMapping.first.DerefLevel > 0)
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@ -186,18 +234,39 @@ CFLAndersAAResult::FunctionInfo::FunctionInfo(const ReachabilitySet &ReachSet) {
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// TODO: Populate function summary here
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}
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AliasAttrs CFLAndersAAResult::FunctionInfo::getAttrs(const Value *V) const {
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assert(V != nullptr);
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AliasAttrs Attr;
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auto Itr = AttrMap.find(V);
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if (Itr != AttrMap.end())
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Attr = Itr->second;
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return Attr;
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}
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bool CFLAndersAAResult::FunctionInfo::mayAlias(const Value *LHS,
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const Value *RHS) const {
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assert(LHS && RHS);
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auto Itr = AliasMap.find(LHS);
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if (Itr == AliasMap.end())
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if (Itr != AliasMap.end()) {
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if (std::binary_search(Itr->second.begin(), Itr->second.end(), RHS,
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std::less<const Value *>()))
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return true;
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}
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// Even if LHS and RHS are not reachable, they may still alias due to their
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// AliasAttrs
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auto AttrsA = getAttrs(LHS);
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auto AttrsB = getAttrs(RHS);
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if (AttrsA.none() || AttrsB.none())
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return false;
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if (hasUnknownOrCallerAttr(AttrsA) || hasUnknownOrCallerAttr(AttrsB))
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return true;
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if (isGlobalOrArgAttr(AttrsA) && isGlobalOrArgAttr(AttrsB))
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return true;
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return false;
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// TODO: Check AliasAttrs before drawing any conclusions
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return std::binary_search(Itr->second.begin(), Itr->second.end(), RHS,
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std::less<const Value *>());
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}
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static void propagate(InstantiatedValue From, InstantiatedValue To,
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@ -247,7 +316,6 @@ static void processWorkListItem(const WorkListItem &Item, const CFLGraph &Graph,
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auto NodeInfo = Graph.getNode(ToNode);
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assert(NodeInfo != nullptr);
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// TODO: propagate AliasAttr as well
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// TODO: propagate field offsets
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// FIXME: Here is a neat trick we can do: since both ReachSet and MemSet holds
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@ -325,6 +393,52 @@ static void processWorkListItem(const WorkListItem &Item, const CFLGraph &Graph,
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}
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}
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static AliasAttrMap buildAttrMap(const CFLGraph &Graph,
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const ReachabilitySet &ReachSet) {
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AliasAttrMap AttrMap;
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std::vector<InstantiatedValue> WorkList, NextList;
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// Initialize each node with its original AliasAttrs in CFLGraph
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for (const auto &Mapping : Graph.value_mappings()) {
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auto Val = Mapping.first;
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auto &ValueInfo = Mapping.second;
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for (unsigned I = 0, E = ValueInfo.getNumLevels(); I < E; ++I) {
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auto Node = InstantiatedValue{Val, I};
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AttrMap.add(Node, ValueInfo.getNodeInfoAtLevel(I).Attr);
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WorkList.push_back(Node);
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}
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}
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while (!WorkList.empty()) {
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for (const auto &Dst : WorkList) {
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auto DstAttr = AttrMap.getAttrs(Dst);
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if (DstAttr.none())
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continue;
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// Propagate attr on the same level
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for (const auto &Mapping : ReachSet.reachableValueAliases(Dst)) {
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auto Src = Mapping.first;
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if (AttrMap.add(Src, DstAttr))
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NextList.push_back(Src);
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}
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// Propagate attr to the levels below
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auto DstBelow = getNodeBelow(Graph, Dst);
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while (DstBelow) {
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if (AttrMap.add(*DstBelow, DstAttr)) {
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NextList.push_back(*DstBelow);
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break;
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}
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DstBelow = getNodeBelow(Graph, *DstBelow);
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}
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}
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WorkList.swap(NextList);
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NextList.clear();
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}
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return AttrMap;
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}
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CFLAndersAAResult::FunctionInfo
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CFLAndersAAResult::buildInfoFrom(const Function &Fn) {
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CFLGraphBuilder<CFLAndersAAResult> GraphBuilder(
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@ -347,7 +461,11 @@ CFLAndersAAResult::buildInfoFrom(const Function &Fn) {
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NextList.clear();
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}
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return FunctionInfo(ReachSet);
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// Now that we have all the reachability info, propagate AliasAttrs according
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// to it
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auto IValueAttrMap = buildAttrMap(Graph, ReachSet);
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return FunctionInfo(ReachSet, std::move(IValueAttrMap));
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}
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void CFLAndersAAResult::scan(const Function &Fn) {
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@ -0,0 +1,61 @@
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; This testcase ensures that AliasAttrs are propagated not only on the same
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; level but also downward.
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; RUN: opt < %s -disable-basicaa -cfl-anders-aa -aa-eval -print-all-alias-modref-info -disable-output 2>&1 | FileCheck %s
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; RUN: opt < %s -aa-pipeline=cfl-anders-aa -passes=aa-eval -print-all-alias-modref-info -disable-output 2>&1 | FileCheck %s
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; CHECK-LABEL: Function: test_attr_below
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; CHECK: MayAlias: i64* %q, i64*** %p
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; CHECK: NoAlias: i64* %esc, i64*** %p
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; CHECK: NoAlias: i64* %esc, i64* %q
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; CHECK: MayAlias: i64* %unknown, i64*** %p
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; CHECK: MayAlias: i64* %q, i64* %unknown
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; CHECK: MayAlias: i64* %esc, i64* %unknown
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; CHECK: MayAlias: i64* %q, i64** %pdrf
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; CHECK: MayAlias: i64* %esc, i64** %pdrf
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; CHECK: MayAlias: i64* %unknown, i64** %pdrf
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; CHECK: MayAlias: i64* %pdrf2, i64* %q
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; CHECK: MayAlias: i64* %esc, i64* %pdrf2
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; CHECK: MayAlias: i64* %pdrf2, i64* %unknown
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define void @test_attr_below(i64*** %p, i64* %q) {
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%esc = alloca i64, align 8
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%escint = ptrtoint i64* %esc to i64
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%unknown = inttoptr i64 %escint to i64*
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%pdrf = load i64**, i64*** %p
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%pdrf2 = load i64*, i64** %pdrf
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ret void
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}
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; CHECK-LABEL: Function: test_attr_assign_below
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; CHECK: MayAlias: i64** %sel, i64*** %p
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; CHECK: MayAlias: i64* %q, i64** %sel
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; CHECK: MayAlias: i64** %a, i64** %sel
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; CHECK: MayAlias: i64** %pdrf, i64** %sel
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; CHECK: MayAlias: i64** %c, i64*** %p
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; CHECK: MayAlias: i64* %q, i64** %c
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; CHECK: MayAlias: i64** %a, i64** %c
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; CHECK: MayAlias: i64** %c, i64** %pdrf
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; CHECK: MayAlias: i64** %c, i64** %sel
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; CHECK: MayAlias: i64* %d, i64*** %p
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; CHECK: MayAlias: i64* %d, i64* %q
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; CHECK: MayAlias: i64* %d, i64** %pdrf
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; CHECK: MayAlias: i64* %d, i64** %sel
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define void @test_attr_assign_below(i64*** %p, i64* %q, i1 %cond) {
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%a = alloca i64*, align 8
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%pdrf = load i64**, i64*** %p
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%sel = select i1 %cond, i64** %a, i64** %pdrf
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%b = alloca i64**, align 8
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store i64** %sel, i64*** %b
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%c = load i64**, i64*** %b
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%d = load i64*, i64** %c
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ret void
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}
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@ -0,0 +1,94 @@
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; This testcase ensures that CFL AA handles escaped values no more conservative than it should
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; RUN: opt < %s -disable-basicaa -cfl-anders-aa -aa-eval -print-all-alias-modref-info -disable-output 2>&1 | FileCheck %s
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; RUN: opt < %s -aa-pipeline=cfl-anders-aa -passes=aa-eval -print-all-alias-modref-info -disable-output 2>&1 | FileCheck %s
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; CHECK-LABEL: Function: test_local
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; CHECK: NoAlias: i32* %a, i32* %b
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; CHECK: MayAlias: i32* %a, i32* %aAlias
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; CHECK: NoAlias: i32* %aAlias, i32* %b
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define void @test_local() {
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%a = alloca i32, align 4
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%b = alloca i32, align 4
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%aint = ptrtoint i32* %a to i64
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%aAlias = inttoptr i64 %aint to i32*
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ret void
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}
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; CHECK-LABEL: Function: test_global_param
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; CHECK: NoAlias: i32* %a, i32** %x
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; CHECK: MayAlias: i32* %a, i32* %xload
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; CHECK: MayAlias: i32* %a, i32* %gload
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; CHECK: MayAlias: i32* %gload, i32* %xload
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; CHECK: MayAlias: i32** %x, i32** @ext_global
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; CHECK: NoAlias: i32* %a, i32** @ext_global
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@ext_global = external global i32*
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define void @test_global_param(i32** %x) {
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%a = alloca i32, align 4
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%aint = ptrtoint i32* %a to i64
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%xload = load i32*, i32** %x
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%gload = load i32*, i32** @ext_global
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ret void
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}
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declare void @external_func(i32**)
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; CHECK-LABEL: Function: test_external_call
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; CHECK: NoAlias: i32* %b, i32* %x
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; CHECK: NoAlias: i32* %b, i32** %a
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; CHECK: MayAlias: i32* %c, i32* %x
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; CHECK: MayAlias: i32* %c, i32** %a
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; CHECK: NoAlias: i32* %b, i32* %c
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define void @test_external_call(i32* %x) {
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%a = alloca i32*, align 8
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%b = alloca i32, align 4
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call void @external_func(i32** %a)
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%c = load i32*, i32** %a
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ret void
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}
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declare void @external_func_readonly(i32**) readonly
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; CHECK-LABEL: Function: test_external_call_func_readonly
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; CHECK: MayAlias: i32* %c, i32* %x
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; CHECK: NoAlias: i32* %c, i32** %a
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define void @test_external_call_func_readonly(i32* %x) {
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%a = alloca i32*, align 8
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%b = alloca i32, align 4
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store i32* %x, i32** %a, align 4
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call void @external_func_readonly(i32** %a)
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%c = load i32*, i32** %a
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ret void
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}
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; CHECK-LABEL: Function: test_external_call_callsite_readonly
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; CHECK: MayAlias: i32* %c, i32* %x
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; CHECK: NoAlias: i32* %c, i32** %a
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define void @test_external_call_callsite_readonly(i32* %x) {
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%a = alloca i32*, align 8
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%b = alloca i32, align 4
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store i32* %x, i32** %a, align 4
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call void @external_func(i32** %a) readonly
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%c = load i32*, i32** %a
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ret void
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}
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declare i32* @external_func_normal_return(i32*)
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; CHECK-LABEL: Function: test_external_call_normal_return
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; CHECK: MayAlias: i32* %c, i32* %x
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; CHECK: MayAlias: i32* %a, i32* %c
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define void @test_external_call_normal_return(i32* %x) {
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%a = alloca i32, align 8
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%b = alloca i32, align 4
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%c = call i32* @external_func_normal_return(i32* %a)
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ret void
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}
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declare noalias i32* @external_func_noalias_return(i32*)
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; CHECK-LABEL: Function: test_external_call_noalias_return
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; CHECK: NoAlias: i32* %c, i32* %x
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; CHECK: NoAlias: i32* %a, i32* %c
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define void @test_external_call_noalias_return(i32* %x) {
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%a = alloca i32, align 8
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%b = alloca i32, align 4
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%c = call i32* @external_func_noalias_return(i32* %a)
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ret void
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}
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