// Alias Analysis" by Zhang Q, Lyu M R, Yuan H, and Su Z. -- to summarize the
// papers, we build a graph of the uses of a variable, where each node is a
// memory location, and each edge is an action that happened on that memory
-// location. The "actions" can be one of Dereference, Reference, Assign, or
-// Assign.
+// location. The "actions" can be one of Dereference, Reference, or Assign.
//
// Two variables are considered as aliasing iff you can reach one value's node
// from the other value's node and the language formed by concatenating all of
struct CFLAliasAnalysis;
-struct FunctionHandle : public CallbackVH {
+struct FunctionHandle final : public CallbackVH {
FunctionHandle(Function *Fn, CFLAliasAnalysis *CFLAA)
: CallbackVH(Fn), CFLAA(CFLAA) {
assert(Fn != nullptr);
assert(CFLAA != nullptr);
}
- ~FunctionHandle() override {}
-
void deleted() override { removeSelfFromCache(); }
void allUsesReplacedWith(Value *) override { removeSelfFromCache(); }
return Iter->second;
}
- AliasResult query(const Location &LocA, const Location &LocB);
+ AliasResult query(const MemoryLocation &LocA, const MemoryLocation &LocB);
- AliasResult alias(const Location &LocA, const Location &LocB) override {
+ AliasResult alias(const MemoryLocation &LocA,
+ const MemoryLocation &LocB) override {
if (LocA.Ptr == LocB.Ptr) {
if (LocA.Size == LocB.Size) {
return MustAlias;
Output.push_back(Edge(&Inst, From1, EdgeType::Assign, AttrNone));
Output.push_back(Edge(&Inst, From2, EdgeType::Assign, AttrNone));
}
+
+ void visitConstantExpr(ConstantExpr *CE) {
+ switch (CE->getOpcode()) {
+ default:
+ llvm_unreachable("Unknown instruction type encountered!");
+// Build the switch statement using the Instruction.def file.
+#define HANDLE_INST(NUM, OPCODE, CLASS) \
+ case Instruction::OPCODE: \
+ visit##OPCODE(*(CLASS *)CE); \
+ break;
+#include "llvm/IR/Instruction.def"
+ }
+ }
};
// For a given instruction, we need to know which Value* to get the
// ----- Various Edge iterators for the graph ----- //
// \brief Iterator for edges. Because this graph is bidirected, we don't
- // allow modificaiton of the edges using this iterator. Additionally, the
+ // allow modification of the edges using this iterator. Additionally, the
// iterator becomes invalid if you add edges to or from the node you're
// getting the edges of.
struct EdgeIterator : public std::iterator<std::forward_iterator_tag,
static void argsToEdges(CFLAliasAnalysis &, Instruction *,
SmallVectorImpl<Edge> &);
+// Gets edges of the given ConstantExpr*, writing them to the SmallVector*.
+static void argsToEdges(CFLAliasAnalysis &, ConstantExpr *,
+ SmallVectorImpl<Edge> &);
+
// Gets the "Level" that one should travel in StratifiedSets
// given an EdgeType.
static Level directionOfEdgeType(EdgeType);
return !isa<CmpInst>(Inst) && !isa<FenceInst>(Inst) && !IsNonInvokeTerminator;
}
+static bool hasUsefulEdges(ConstantExpr *CE) {
+ // ConstantExpr doesn't have terminators, invokes, or fences, so only needs
+ // to check for compares.
+ return CE->getOpcode() != Instruction::ICmp &&
+ CE->getOpcode() != Instruction::FCmp;
+}
+
static Optional<StratifiedAttr> valueToAttrIndex(Value *Val) {
if (isa<GlobalValue>(Val))
return AttrGlobalIndex;
v.visit(Inst);
}
+static void argsToEdges(CFLAliasAnalysis &Analysis, ConstantExpr *CE,
+ SmallVectorImpl<Edge> &Output) {
+ assert(hasUsefulEdges(CE) && "Expected constant expr to have 'useful' edges");
+ GetEdgesVisitor v(Analysis, Output);
+ v.visitConstantExpr(CE);
+}
+
static Level directionOfEdgeType(EdgeType Weight) {
switch (Weight) {
case EdgeType::Reference:
Worklist.push_back(&CExprToCollapse);
SmallVector<Edge, 8> ConstexprEdges;
+ SmallPtrSet<ConstantExpr *, 4> Visited;
while (!Worklist.empty()) {
auto *CExpr = Worklist.pop_back_val();
- std::unique_ptr<Instruction> Inst(CExpr->getAsInstruction());
- if (!hasUsefulEdges(Inst.get()))
+ if (!hasUsefulEdges(CExpr))
continue;
ConstexprEdges.clear();
- argsToEdges(Analysis, Inst.get(), ConstexprEdges);
+ argsToEdges(Analysis, CExpr, ConstexprEdges);
for (auto &Edge : ConstexprEdges) {
- if (Edge.From == Inst.get())
- Edge.From = CExpr;
- else if (auto *Nested = dyn_cast<ConstantExpr>(Edge.From))
- Worklist.push_back(Nested);
-
- if (Edge.To == Inst.get())
- Edge.To = CExpr;
- else if (auto *Nested = dyn_cast<ConstantExpr>(Edge.To))
- Worklist.push_back(Nested);
+ if (auto *Nested = dyn_cast<ConstantExpr>(Edge.From))
+ if (Visited.insert(Nested).second)
+ Worklist.push_back(Nested);
+
+ if (auto *Nested = dyn_cast<ConstantExpr>(Edge.To))
+ if (Visited.insert(Nested).second)
+ Worklist.push_back(Nested);
}
Results.append(ConstexprEdges.begin(), ConstexprEdges.end());
Handles.push_front(FunctionHandle(Fn, this));
}
-AliasAnalysis::AliasResult
-CFLAliasAnalysis::query(const AliasAnalysis::Location &LocA,
- const AliasAnalysis::Location &LocB) {
+AliasResult CFLAliasAnalysis::query(const MemoryLocation &LocA,
+ const MemoryLocation &LocB) {
auto *ValA = const_cast<Value *>(LocA.Ptr);
auto *ValB = const_cast<Value *>(LocB.Ptr);
// The only times this is known to happen are when globals + InlineAsm
// are involved
DEBUG(dbgs() << "CFLAA: could not extract parent function information.\n");
- return AliasAnalysis::MayAlias;
+ return MayAlias;
}
if (MaybeFnA.hasValue()) {
auto &Sets = MaybeInfo->Sets;
auto MaybeA = Sets.find(ValA);
if (!MaybeA.hasValue())
- return AliasAnalysis::MayAlias;
+ return MayAlias;
auto MaybeB = Sets.find(ValB);
if (!MaybeB.hasValue())
- return AliasAnalysis::MayAlias;
+ return MayAlias;
auto SetA = *MaybeA;
auto SetB = *MaybeB;
// the sets has no values that could legally be altered by changing the value
// of an argument or global, then we don't have to be as conservative.
if (AttrsA.any() && AttrsB.any())
- return AliasAnalysis::MayAlias;
+ return MayAlias;
// We currently unify things even if the accesses to them may not be in
// bounds, so we can't return partial alias here because we don't
// differentiate
if (SetA.Index == SetB.Index)
- return AliasAnalysis::MayAlias;
+ return MayAlias;
- return AliasAnalysis::NoAlias;
+ return NoAlias;
}
bool CFLAliasAnalysis::doInitialization(Module &M) {
projects / oota-llvm.git / blobdiff