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febf86d7e3
operations on the call graph. This one forms a cycle, and while not as complex as removing an internal edge from an SCC, it involves a reasonable amount of work to find all of the nodes newly connected in a cycle. Also somewhat alarming is the worst case complexity here: it might have to walk roughly the entire SCC inverse DAG to insert a single edge. This is carefully documented in the API (I hope). git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207935 91177308-0d34-0410-b5e6-96231b3b80d8
729 lines
26 KiB
C++
729 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)))
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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))
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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()))
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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 childen, 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 childen, 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))
|
|
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))
|
|
printNodes(OS, N, Printed);
|
|
|
|
for (LazyCallGraph::SCC &SCC : G.postorder_sccs())
|
|
printSCC(OS, SCC);
|
|
|
|
return PreservedAnalyses::all();
|
|
|
|
}
|