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64e6092133
a print method. This was formulated on a bad idea, but sadly I didn't uncover how bad this was until I got further down the path. I had hoped that we could provide a low boilerplate way of printing analyses, but it just doesn't seem like this really fits the needs of the analyses. Not all analyses really want to do printing, and those that do don't all use the same interface. Instead, with the new pass manager let's just take advantage of the fact that creating an explicit printer pass like the LCG has is pretty low boilerplate already and rely on that for testing. llvm-svn: 225861
728 lines
26 KiB
C++
728 lines
26 KiB
C++
//===- LazyCallGraph.cpp - Analysis of a Module's call graph --------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/LazyCallGraph.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/IR/CallSite.h"
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#include "llvm/IR/InstVisitor.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/PassManager.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm;
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#define DEBUG_TYPE "lcg"
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static void findCallees(
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SmallVectorImpl<Constant *> &Worklist, SmallPtrSetImpl<Constant *> &Visited,
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SmallVectorImpl<PointerUnion<Function *, LazyCallGraph::Node *>> &Callees,
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DenseMap<Function *, size_t> &CalleeIndexMap) {
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while (!Worklist.empty()) {
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Constant *C = Worklist.pop_back_val();
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if (Function *F = dyn_cast<Function>(C)) {
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// Note that we consider *any* function with a definition to be a viable
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// edge. Even if the function's definition is subject to replacement by
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// some other module (say, a weak definition) there may still be
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// optimizations which essentially speculate based on the definition and
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// a way to check that the specific definition is in fact the one being
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// used. For example, this could be done by moving the weak definition to
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// a strong (internal) definition and making the weak definition be an
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// alias. Then a test of the address of the weak function against the new
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// strong definition's address would be an effective way to determine the
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// safety of optimizing a direct call edge.
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if (!F->isDeclaration() &&
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CalleeIndexMap.insert(std::make_pair(F, Callees.size())).second) {
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DEBUG(dbgs() << " Added callable function: " << F->getName()
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<< "\n");
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Callees.push_back(F);
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}
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continue;
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}
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for (Value *Op : C->operand_values())
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if (Visited.insert(cast<Constant>(Op)).second)
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Worklist.push_back(cast<Constant>(Op));
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}
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}
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LazyCallGraph::Node::Node(LazyCallGraph &G, Function &F)
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: G(&G), F(F), DFSNumber(0), LowLink(0) {
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DEBUG(dbgs() << " Adding functions called by '" << F.getName()
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<< "' to the graph.\n");
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SmallVector<Constant *, 16> Worklist;
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SmallPtrSet<Constant *, 16> Visited;
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// Find all the potential callees in this function. First walk the
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// instructions and add every operand which is a constant to the worklist.
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for (BasicBlock &BB : F)
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for (Instruction &I : BB)
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for (Value *Op : I.operand_values())
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if (Constant *C = dyn_cast<Constant>(Op))
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if (Visited.insert(C).second)
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Worklist.push_back(C);
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// We've collected all the constant (and thus potentially function or
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// function containing) operands to all of the instructions in the function.
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// Process them (recursively) collecting every function found.
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findCallees(Worklist, Visited, Callees, CalleeIndexMap);
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}
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void LazyCallGraph::Node::insertEdgeInternal(Function &Callee) {
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if (Node *N = G->lookup(Callee))
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return insertEdgeInternal(*N);
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CalleeIndexMap.insert(std::make_pair(&Callee, Callees.size()));
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Callees.push_back(&Callee);
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}
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void LazyCallGraph::Node::insertEdgeInternal(Node &CalleeN) {
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CalleeIndexMap.insert(std::make_pair(&CalleeN.getFunction(), Callees.size()));
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Callees.push_back(&CalleeN);
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}
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void LazyCallGraph::Node::removeEdgeInternal(Function &Callee) {
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auto IndexMapI = CalleeIndexMap.find(&Callee);
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assert(IndexMapI != CalleeIndexMap.end() &&
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"Callee not in the callee set for this caller?");
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Callees[IndexMapI->second] = nullptr;
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CalleeIndexMap.erase(IndexMapI);
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}
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LazyCallGraph::LazyCallGraph(Module &M) : NextDFSNumber(0) {
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DEBUG(dbgs() << "Building CG for module: " << M.getModuleIdentifier()
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<< "\n");
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for (Function &F : M)
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if (!F.isDeclaration() && !F.hasLocalLinkage())
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if (EntryIndexMap.insert(std::make_pair(&F, EntryNodes.size())).second) {
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DEBUG(dbgs() << " Adding '" << F.getName()
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<< "' to entry set of the graph.\n");
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EntryNodes.push_back(&F);
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}
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// Now add entry nodes for functions reachable via initializers to globals.
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SmallVector<Constant *, 16> Worklist;
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SmallPtrSet<Constant *, 16> Visited;
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for (GlobalVariable &GV : M.globals())
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if (GV.hasInitializer())
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if (Visited.insert(GV.getInitializer()).second)
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Worklist.push_back(GV.getInitializer());
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DEBUG(dbgs() << " Adding functions referenced by global initializers to the "
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"entry set.\n");
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findCallees(Worklist, Visited, EntryNodes, EntryIndexMap);
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for (auto &Entry : EntryNodes) {
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assert(!Entry.isNull() &&
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"We can't have removed edges before we finish the constructor!");
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if (Function *F = Entry.dyn_cast<Function *>())
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SCCEntryNodes.push_back(F);
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else
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SCCEntryNodes.push_back(&Entry.get<Node *>()->getFunction());
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}
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}
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LazyCallGraph::LazyCallGraph(LazyCallGraph &&G)
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: BPA(std::move(G.BPA)), NodeMap(std::move(G.NodeMap)),
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EntryNodes(std::move(G.EntryNodes)),
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EntryIndexMap(std::move(G.EntryIndexMap)), SCCBPA(std::move(G.SCCBPA)),
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SCCMap(std::move(G.SCCMap)), LeafSCCs(std::move(G.LeafSCCs)),
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DFSStack(std::move(G.DFSStack)),
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SCCEntryNodes(std::move(G.SCCEntryNodes)),
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NextDFSNumber(G.NextDFSNumber) {
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updateGraphPtrs();
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}
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LazyCallGraph &LazyCallGraph::operator=(LazyCallGraph &&G) {
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BPA = std::move(G.BPA);
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NodeMap = std::move(G.NodeMap);
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EntryNodes = std::move(G.EntryNodes);
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EntryIndexMap = std::move(G.EntryIndexMap);
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SCCBPA = std::move(G.SCCBPA);
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SCCMap = std::move(G.SCCMap);
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LeafSCCs = std::move(G.LeafSCCs);
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DFSStack = std::move(G.DFSStack);
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SCCEntryNodes = std::move(G.SCCEntryNodes);
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NextDFSNumber = G.NextDFSNumber;
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updateGraphPtrs();
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return *this;
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}
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void LazyCallGraph::SCC::insert(Node &N) {
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N.DFSNumber = N.LowLink = -1;
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Nodes.push_back(&N);
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G->SCCMap[&N] = this;
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}
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bool LazyCallGraph::SCC::isDescendantOf(const SCC &C) const {
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// Walk up the parents of this SCC and verify that we eventually find C.
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SmallVector<const SCC *, 4> AncestorWorklist;
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AncestorWorklist.push_back(this);
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do {
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const SCC *AncestorC = AncestorWorklist.pop_back_val();
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if (AncestorC->isChildOf(C))
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return true;
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for (const SCC *ParentC : AncestorC->ParentSCCs)
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AncestorWorklist.push_back(ParentC);
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} while (!AncestorWorklist.empty());
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return false;
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}
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void LazyCallGraph::SCC::insertIntraSCCEdge(Node &CallerN, Node &CalleeN) {
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// First insert it into the caller.
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CallerN.insertEdgeInternal(CalleeN);
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assert(G->SCCMap.lookup(&CallerN) == this && "Caller must be in this SCC.");
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assert(G->SCCMap.lookup(&CalleeN) == this && "Callee must be in this SCC.");
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// Nothing changes about this SCC or any other.
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}
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void LazyCallGraph::SCC::insertOutgoingEdge(Node &CallerN, Node &CalleeN) {
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// First insert it into the caller.
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CallerN.insertEdgeInternal(CalleeN);
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assert(G->SCCMap.lookup(&CallerN) == this && "Caller must be in this SCC.");
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SCC &CalleeC = *G->SCCMap.lookup(&CalleeN);
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assert(&CalleeC != this && "Callee must not be in this SCC.");
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assert(CalleeC.isDescendantOf(*this) &&
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"Callee must be a descendant of the Caller.");
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// The only change required is to add this SCC to the parent set of the callee.
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CalleeC.ParentSCCs.insert(this);
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}
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SmallVector<LazyCallGraph::SCC *, 1>
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LazyCallGraph::SCC::insertIncomingEdge(Node &CallerN, Node &CalleeN) {
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// First insert it into the caller.
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CallerN.insertEdgeInternal(CalleeN);
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assert(G->SCCMap.lookup(&CalleeN) == this && "Callee must be in this SCC.");
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SCC &CallerC = *G->SCCMap.lookup(&CallerN);
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assert(&CallerC != this && "Caller must not be in this SCC.");
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assert(CallerC.isDescendantOf(*this) &&
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"Caller must be a descendant of the Callee.");
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// The algorithm we use for merging SCCs based on the cycle introduced here
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// is to walk the SCC inverted DAG formed by the parent SCC sets. The inverse
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// graph has the same cycle properties as the actual DAG of the SCCs, and
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// when forming SCCs lazily by a DFS, the bottom of the graph won't exist in
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// many cases which should prune the search space.
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//
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// FIXME: We can get this pruning behavior even after the incremental SCC
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// formation by leaving behind (conservative) DFS numberings in the nodes,
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// and pruning the search with them. These would need to be cleverly updated
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// during the removal of intra-SCC edges, but could be preserved
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// conservatively.
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// The set of SCCs that are connected to the caller, and thus will
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// participate in the merged connected component.
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SmallPtrSet<SCC *, 8> ConnectedSCCs;
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ConnectedSCCs.insert(this);
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ConnectedSCCs.insert(&CallerC);
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// We build up a DFS stack of the parents chains.
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SmallVector<std::pair<SCC *, SCC::parent_iterator>, 8> DFSSCCs;
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SmallPtrSet<SCC *, 8> VisitedSCCs;
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int ConnectedDepth = -1;
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SCC *C = this;
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parent_iterator I = parent_begin(), E = parent_end();
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for (;;) {
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while (I != E) {
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SCC &ParentSCC = *I++;
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// If we have already processed this parent SCC, skip it, and remember
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// whether it was connected so we don't have to check the rest of the
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// stack. This also handles when we reach a child of the 'this' SCC (the
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// callee) which terminates the search.
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if (ConnectedSCCs.count(&ParentSCC)) {
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ConnectedDepth = std::max<int>(ConnectedDepth, DFSSCCs.size());
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continue;
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}
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if (VisitedSCCs.count(&ParentSCC))
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continue;
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// We fully explore the depth-first space, adding nodes to the connected
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// set only as we pop them off, so "recurse" by rotating to the parent.
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DFSSCCs.push_back(std::make_pair(C, I));
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C = &ParentSCC;
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I = ParentSCC.parent_begin();
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E = ParentSCC.parent_end();
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}
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// If we've found a connection anywhere below this point on the stack (and
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// thus up the parent graph from the caller), the current node needs to be
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// added to the connected set now that we've processed all of its parents.
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if ((int)DFSSCCs.size() == ConnectedDepth) {
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--ConnectedDepth; // We're finished with this connection.
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ConnectedSCCs.insert(C);
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} else {
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// Otherwise remember that its parents don't ever connect.
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assert(ConnectedDepth < (int)DFSSCCs.size() &&
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"Cannot have a connected depth greater than the DFS depth!");
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VisitedSCCs.insert(C);
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}
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if (DFSSCCs.empty())
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break; // We've walked all the parents of the caller transitively.
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// Pop off the prior node and position to unwind the depth first recursion.
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std::tie(C, I) = DFSSCCs.pop_back_val();
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E = C->parent_end();
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}
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// Now that we have identified all of the SCCs which need to be merged into
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// a connected set with the inserted edge, merge all of them into this SCC.
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// FIXME: This operation currently creates ordering stability problems
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// because we don't use stably ordered containers for the parent SCCs or the
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// connected SCCs.
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unsigned NewNodeBeginIdx = Nodes.size();
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for (SCC *C : ConnectedSCCs) {
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if (C == this)
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continue;
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for (SCC *ParentC : C->ParentSCCs)
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if (!ConnectedSCCs.count(ParentC))
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ParentSCCs.insert(ParentC);
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C->ParentSCCs.clear();
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for (Node *N : *C) {
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for (Node &ChildN : *N) {
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SCC &ChildC = *G->SCCMap.lookup(&ChildN);
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if (&ChildC != C)
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ChildC.ParentSCCs.erase(C);
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}
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G->SCCMap[N] = this;
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Nodes.push_back(N);
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}
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C->Nodes.clear();
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}
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for (auto I = Nodes.begin() + NewNodeBeginIdx, E = Nodes.end(); I != E; ++I)
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for (Node &ChildN : **I) {
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SCC &ChildC = *G->SCCMap.lookup(&ChildN);
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if (&ChildC != this)
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ChildC.ParentSCCs.insert(this);
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}
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// We return the list of SCCs which were merged so that callers can
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// invalidate any data they have associated with those SCCs. Note that these
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// SCCs are no longer in an interesting state (they are totally empty) but
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// the pointers will remain stable for the life of the graph itself.
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return SmallVector<SCC *, 1>(ConnectedSCCs.begin(), ConnectedSCCs.end());
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}
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void LazyCallGraph::SCC::removeInterSCCEdge(Node &CallerN, Node &CalleeN) {
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// First remove it from the node.
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CallerN.removeEdgeInternal(CalleeN.getFunction());
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assert(G->SCCMap.lookup(&CallerN) == this &&
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"The caller must be a member of this SCC.");
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SCC &CalleeC = *G->SCCMap.lookup(&CalleeN);
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assert(&CalleeC != this &&
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"This API only supports the rmoval of inter-SCC edges.");
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assert(std::find(G->LeafSCCs.begin(), G->LeafSCCs.end(), this) ==
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G->LeafSCCs.end() &&
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"Cannot have a leaf SCC caller with a different SCC callee.");
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bool HasOtherCallToCalleeC = false;
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bool HasOtherCallOutsideSCC = false;
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for (Node *N : *this) {
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for (Node &OtherCalleeN : *N) {
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SCC &OtherCalleeC = *G->SCCMap.lookup(&OtherCalleeN);
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if (&OtherCalleeC == &CalleeC) {
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HasOtherCallToCalleeC = true;
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break;
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}
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if (&OtherCalleeC != this)
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HasOtherCallOutsideSCC = true;
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}
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if (HasOtherCallToCalleeC)
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break;
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}
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// Because the SCCs form a DAG, deleting such an edge cannot change the set
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// of SCCs in the graph. However, it may cut an edge of the SCC DAG, making
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// the caller no longer a parent of the callee. Walk the other call edges
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// in the caller to tell.
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if (!HasOtherCallToCalleeC) {
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bool Removed = CalleeC.ParentSCCs.erase(this);
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(void)Removed;
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assert(Removed &&
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"Did not find the caller SCC in the callee SCC's parent list!");
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// It may orphan an SCC if it is the last edge reaching it, but that does
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// not violate any invariants of the graph.
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if (CalleeC.ParentSCCs.empty())
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DEBUG(dbgs() << "LCG: Update removing " << CallerN.getFunction().getName()
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<< " -> " << CalleeN.getFunction().getName()
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<< " edge orphaned the callee's SCC!\n");
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}
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// It may make the Caller SCC a leaf SCC.
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if (!HasOtherCallOutsideSCC)
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G->LeafSCCs.push_back(this);
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}
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void LazyCallGraph::SCC::internalDFS(
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SmallVectorImpl<std::pair<Node *, Node::iterator>> &DFSStack,
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SmallVectorImpl<Node *> &PendingSCCStack, Node *N,
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SmallVectorImpl<SCC *> &ResultSCCs) {
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Node::iterator I = N->begin();
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N->LowLink = N->DFSNumber = 1;
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int NextDFSNumber = 2;
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for (;;) {
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assert(N->DFSNumber != 0 && "We should always assign a DFS number "
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"before processing a node.");
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// We simulate recursion by popping out of the nested loop and continuing.
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Node::iterator E = N->end();
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while (I != E) {
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Node &ChildN = *I;
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if (SCC *ChildSCC = G->SCCMap.lookup(&ChildN)) {
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// Check if we have reached a node in the new (known connected) set of
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// this SCC. If so, the entire stack is necessarily in that set and we
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// can re-start.
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if (ChildSCC == this) {
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insert(*N);
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while (!PendingSCCStack.empty())
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insert(*PendingSCCStack.pop_back_val());
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while (!DFSStack.empty())
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insert(*DFSStack.pop_back_val().first);
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return;
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}
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// If this child isn't currently in this SCC, no need to process it.
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// However, we do need to remove this SCC from its SCC's parent set.
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ChildSCC->ParentSCCs.erase(this);
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++I;
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continue;
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}
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if (ChildN.DFSNumber == 0) {
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// Mark that we should start at this child when next this node is the
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// top of the stack. We don't start at the next child to ensure this
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// child's lowlink is reflected.
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DFSStack.push_back(std::make_pair(N, I));
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// Continue, resetting to the child node.
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ChildN.LowLink = ChildN.DFSNumber = NextDFSNumber++;
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N = &ChildN;
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I = ChildN.begin();
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E = ChildN.end();
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continue;
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}
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// Track the lowest link of the children, if any are still in the stack.
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// Any child not on the stack will have a LowLink of -1.
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assert(ChildN.LowLink != 0 &&
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"Low-link must not be zero with a non-zero DFS number.");
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if (ChildN.LowLink >= 0 && ChildN.LowLink < N->LowLink)
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N->LowLink = ChildN.LowLink;
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++I;
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}
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if (N->LowLink == N->DFSNumber) {
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ResultSCCs.push_back(G->formSCC(N, PendingSCCStack));
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if (DFSStack.empty())
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return;
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} else {
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// At this point we know that N cannot ever be an SCC root. Its low-link
|
|
// is not its dfs-number, and we've processed all of its children. It is
|
|
// just sitting here waiting until some node further down the stack gets
|
|
// low-link == dfs-number and pops it off as well. Move it to the pending
|
|
// stack which is pulled into the next SCC to be formed.
|
|
PendingSCCStack.push_back(N);
|
|
|
|
assert(!DFSStack.empty() && "We shouldn't have an empty stack!");
|
|
}
|
|
|
|
N = DFSStack.back().first;
|
|
I = DFSStack.back().second;
|
|
DFSStack.pop_back();
|
|
}
|
|
}
|
|
|
|
SmallVector<LazyCallGraph::SCC *, 1>
|
|
LazyCallGraph::SCC::removeIntraSCCEdge(Node &CallerN,
|
|
Node &CalleeN) {
|
|
// First remove it from the node.
|
|
CallerN.removeEdgeInternal(CalleeN.getFunction());
|
|
|
|
// We return a list of the resulting *new* SCCs in postorder.
|
|
SmallVector<SCC *, 1> ResultSCCs;
|
|
|
|
// Direct recursion doesn't impact the SCC graph at all.
|
|
if (&CallerN == &CalleeN)
|
|
return ResultSCCs;
|
|
|
|
// The worklist is every node in the original SCC.
|
|
SmallVector<Node *, 1> Worklist;
|
|
Worklist.swap(Nodes);
|
|
for (Node *N : Worklist) {
|
|
// The nodes formerly in this SCC are no longer in any SCC.
|
|
N->DFSNumber = 0;
|
|
N->LowLink = 0;
|
|
G->SCCMap.erase(N);
|
|
}
|
|
assert(Worklist.size() > 1 && "We have to have at least two nodes to have an "
|
|
"edge between them that is within the SCC.");
|
|
|
|
// The callee can already reach every node in this SCC (by definition). It is
|
|
// the only node we know will stay inside this SCC. Everything which
|
|
// transitively reaches Callee will also remain in the SCC. To model this we
|
|
// incrementally add any chain of nodes which reaches something in the new
|
|
// node set to the new node set. This short circuits one side of the Tarjan's
|
|
// walk.
|
|
insert(CalleeN);
|
|
|
|
// We're going to do a full mini-Tarjan's walk using a local stack here.
|
|
SmallVector<std::pair<Node *, Node::iterator>, 4> DFSStack;
|
|
SmallVector<Node *, 4> PendingSCCStack;
|
|
do {
|
|
Node *N = Worklist.pop_back_val();
|
|
if (N->DFSNumber == 0)
|
|
internalDFS(DFSStack, PendingSCCStack, N, ResultSCCs);
|
|
|
|
assert(DFSStack.empty() && "Didn't flush the entire DFS stack!");
|
|
assert(PendingSCCStack.empty() && "Didn't flush all pending SCC nodes!");
|
|
} while (!Worklist.empty());
|
|
|
|
// Now we need to reconnect the current SCC to the graph.
|
|
bool IsLeafSCC = true;
|
|
for (Node *N : Nodes) {
|
|
for (Node &ChildN : *N) {
|
|
SCC &ChildSCC = *G->SCCMap.lookup(&ChildN);
|
|
if (&ChildSCC == this)
|
|
continue;
|
|
ChildSCC.ParentSCCs.insert(this);
|
|
IsLeafSCC = false;
|
|
}
|
|
}
|
|
#ifndef NDEBUG
|
|
if (!ResultSCCs.empty())
|
|
assert(!IsLeafSCC && "This SCC cannot be a leaf as we have split out new "
|
|
"SCCs by removing this edge.");
|
|
if (!std::any_of(G->LeafSCCs.begin(), G->LeafSCCs.end(),
|
|
[&](SCC *C) { return C == this; }))
|
|
assert(!IsLeafSCC && "This SCC cannot be a leaf as it already had child "
|
|
"SCCs before we removed this edge.");
|
|
#endif
|
|
// If this SCC stopped being a leaf through this edge removal, remove it from
|
|
// the leaf SCC list.
|
|
if (!IsLeafSCC && !ResultSCCs.empty())
|
|
G->LeafSCCs.erase(std::remove(G->LeafSCCs.begin(), G->LeafSCCs.end(), this),
|
|
G->LeafSCCs.end());
|
|
|
|
// Return the new list of SCCs.
|
|
return ResultSCCs;
|
|
}
|
|
|
|
void LazyCallGraph::insertEdge(Node &CallerN, Function &Callee) {
|
|
assert(SCCMap.empty() && DFSStack.empty() &&
|
|
"This method cannot be called after SCCs have been formed!");
|
|
|
|
return CallerN.insertEdgeInternal(Callee);
|
|
}
|
|
|
|
void LazyCallGraph::removeEdge(Node &CallerN, Function &Callee) {
|
|
assert(SCCMap.empty() && DFSStack.empty() &&
|
|
"This method cannot be called after SCCs have been formed!");
|
|
|
|
return CallerN.removeEdgeInternal(Callee);
|
|
}
|
|
|
|
LazyCallGraph::Node &LazyCallGraph::insertInto(Function &F, Node *&MappedN) {
|
|
return *new (MappedN = BPA.Allocate()) Node(*this, F);
|
|
}
|
|
|
|
void LazyCallGraph::updateGraphPtrs() {
|
|
// Process all nodes updating the graph pointers.
|
|
{
|
|
SmallVector<Node *, 16> Worklist;
|
|
for (auto &Entry : EntryNodes)
|
|
if (Node *EntryN = Entry.dyn_cast<Node *>())
|
|
Worklist.push_back(EntryN);
|
|
|
|
while (!Worklist.empty()) {
|
|
Node *N = Worklist.pop_back_val();
|
|
N->G = this;
|
|
for (auto &Callee : N->Callees)
|
|
if (!Callee.isNull())
|
|
if (Node *CalleeN = Callee.dyn_cast<Node *>())
|
|
Worklist.push_back(CalleeN);
|
|
}
|
|
}
|
|
|
|
// Process all SCCs updating the graph pointers.
|
|
{
|
|
SmallVector<SCC *, 16> Worklist(LeafSCCs.begin(), LeafSCCs.end());
|
|
|
|
while (!Worklist.empty()) {
|
|
SCC *C = Worklist.pop_back_val();
|
|
C->G = this;
|
|
Worklist.insert(Worklist.end(), C->ParentSCCs.begin(),
|
|
C->ParentSCCs.end());
|
|
}
|
|
}
|
|
}
|
|
|
|
LazyCallGraph::SCC *LazyCallGraph::formSCC(Node *RootN,
|
|
SmallVectorImpl<Node *> &NodeStack) {
|
|
// The tail of the stack is the new SCC. Allocate the SCC and pop the stack
|
|
// into it.
|
|
SCC *NewSCC = new (SCCBPA.Allocate()) SCC(*this);
|
|
|
|
while (!NodeStack.empty() && NodeStack.back()->DFSNumber > RootN->DFSNumber) {
|
|
assert(NodeStack.back()->LowLink >= RootN->LowLink &&
|
|
"We cannot have a low link in an SCC lower than its root on the "
|
|
"stack!");
|
|
NewSCC->insert(*NodeStack.pop_back_val());
|
|
}
|
|
NewSCC->insert(*RootN);
|
|
|
|
// A final pass over all edges in the SCC (this remains linear as we only
|
|
// do this once when we build the SCC) to connect it to the parent sets of
|
|
// its children.
|
|
bool IsLeafSCC = true;
|
|
for (Node *SCCN : NewSCC->Nodes)
|
|
for (Node &SCCChildN : *SCCN) {
|
|
SCC &ChildSCC = *SCCMap.lookup(&SCCChildN);
|
|
if (&ChildSCC == NewSCC)
|
|
continue;
|
|
ChildSCC.ParentSCCs.insert(NewSCC);
|
|
IsLeafSCC = false;
|
|
}
|
|
|
|
// For the SCCs where we fine no child SCCs, add them to the leaf list.
|
|
if (IsLeafSCC)
|
|
LeafSCCs.push_back(NewSCC);
|
|
|
|
return NewSCC;
|
|
}
|
|
|
|
LazyCallGraph::SCC *LazyCallGraph::getNextSCCInPostOrder() {
|
|
Node *N;
|
|
Node::iterator I;
|
|
if (!DFSStack.empty()) {
|
|
N = DFSStack.back().first;
|
|
I = DFSStack.back().second;
|
|
DFSStack.pop_back();
|
|
} else {
|
|
// If we've handled all candidate entry nodes to the SCC forest, we're done.
|
|
do {
|
|
if (SCCEntryNodes.empty())
|
|
return nullptr;
|
|
|
|
N = &get(*SCCEntryNodes.pop_back_val());
|
|
} while (N->DFSNumber != 0);
|
|
I = N->begin();
|
|
N->LowLink = N->DFSNumber = 1;
|
|
NextDFSNumber = 2;
|
|
}
|
|
|
|
for (;;) {
|
|
assert(N->DFSNumber != 0 && "We should always assign a DFS number "
|
|
"before placing a node onto the stack.");
|
|
|
|
Node::iterator E = N->end();
|
|
while (I != E) {
|
|
Node &ChildN = *I;
|
|
if (ChildN.DFSNumber == 0) {
|
|
// Mark that we should start at this child when next this node is the
|
|
// top of the stack. We don't start at the next child to ensure this
|
|
// child's lowlink is reflected.
|
|
DFSStack.push_back(std::make_pair(N, N->begin()));
|
|
|
|
// Recurse onto this node via a tail call.
|
|
assert(!SCCMap.count(&ChildN) &&
|
|
"Found a node with 0 DFS number but already in an SCC!");
|
|
ChildN.LowLink = ChildN.DFSNumber = NextDFSNumber++;
|
|
N = &ChildN;
|
|
I = ChildN.begin();
|
|
E = ChildN.end();
|
|
continue;
|
|
}
|
|
|
|
// Track the lowest link of the children, if any are still in the stack.
|
|
assert(ChildN.LowLink != 0 &&
|
|
"Low-link must not be zero with a non-zero DFS number.");
|
|
if (ChildN.LowLink >= 0 && ChildN.LowLink < N->LowLink)
|
|
N->LowLink = ChildN.LowLink;
|
|
++I;
|
|
}
|
|
|
|
if (N->LowLink == N->DFSNumber)
|
|
// Form the new SCC out of the top of the DFS stack.
|
|
return formSCC(N, PendingSCCStack);
|
|
|
|
// At this point we know that N cannot ever be an SCC root. Its low-link
|
|
// is not its dfs-number, and we've processed all of its children. It is
|
|
// just sitting here waiting until some node further down the stack gets
|
|
// low-link == dfs-number and pops it off as well. Move it to the pending
|
|
// stack which is pulled into the next SCC to be formed.
|
|
PendingSCCStack.push_back(N);
|
|
|
|
assert(!DFSStack.empty() && "We never found a viable root!");
|
|
N = DFSStack.back().first;
|
|
I = DFSStack.back().second;
|
|
DFSStack.pop_back();
|
|
}
|
|
}
|
|
|
|
char LazyCallGraphAnalysis::PassID;
|
|
|
|
LazyCallGraphPrinterPass::LazyCallGraphPrinterPass(raw_ostream &OS) : OS(OS) {}
|
|
|
|
static void printNodes(raw_ostream &OS, LazyCallGraph::Node &N,
|
|
SmallPtrSetImpl<LazyCallGraph::Node *> &Printed) {
|
|
// Recurse depth first through the nodes.
|
|
for (LazyCallGraph::Node &ChildN : N)
|
|
if (Printed.insert(&ChildN).second)
|
|
printNodes(OS, ChildN, Printed);
|
|
|
|
OS << " Call edges in function: " << N.getFunction().getName() << "\n";
|
|
for (LazyCallGraph::iterator I = N.begin(), E = N.end(); I != E; ++I)
|
|
OS << " -> " << I->getFunction().getName() << "\n";
|
|
|
|
OS << "\n";
|
|
}
|
|
|
|
static void printSCC(raw_ostream &OS, LazyCallGraph::SCC &SCC) {
|
|
ptrdiff_t SCCSize = std::distance(SCC.begin(), SCC.end());
|
|
OS << " SCC with " << SCCSize << " functions:\n";
|
|
|
|
for (LazyCallGraph::Node *N : SCC)
|
|
OS << " " << N->getFunction().getName() << "\n";
|
|
|
|
OS << "\n";
|
|
}
|
|
|
|
PreservedAnalyses LazyCallGraphPrinterPass::run(Module &M,
|
|
ModuleAnalysisManager *AM) {
|
|
LazyCallGraph &G = AM->getResult<LazyCallGraphAnalysis>(M);
|
|
|
|
OS << "Printing the call graph for module: " << M.getModuleIdentifier()
|
|
<< "\n\n";
|
|
|
|
SmallPtrSet<LazyCallGraph::Node *, 16> Printed;
|
|
for (LazyCallGraph::Node &N : G)
|
|
if (Printed.insert(&N).second)
|
|
printNodes(OS, N, Printed);
|
|
|
|
for (LazyCallGraph::SCC &SCC : G.postorder_sccs())
|
|
printSCC(OS, SCC);
|
|
|
|
return PreservedAnalyses::all();
|
|
}
|