1 files changed, 195 insertions, 0 deletions
diff --git a/lib/Analysis/LazyCallGraph.cpp b/lib/Analysis/LazyCallGraph.cpp
new file mode 100644
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+++ b/lib/Analysis/LazyCallGraph.cpp
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+//===- LazyCallGraph.cpp - Analysis of a Module's call graph --------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/LazyCallGraph.h"
+#include "llvm/ADT/SCCIterator.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/PassManager.h"
+#include "llvm/Support/CallSite.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/InstVisitor.h"
+
+using namespace llvm;
+
+static void findCallees(
+    SmallVectorImpl<Constant *> &Worklist, SmallPtrSetImpl<Constant *> &Visited,
+    SmallVectorImpl<PointerUnion<Function *, LazyCallGraph::Node *> > &Callees,
+    SmallPtrSetImpl<Function *> &CalleeSet) {
+  while (!Worklist.empty()) {
+    Constant *C = Worklist.pop_back_val();
+
+    if (Function *F = dyn_cast<Function>(C)) {
+      // Note that we consider *any* function with a definition to be a viable
+      // edge. Even if the function's definition is subject to replacement by
+      // some other module (say, a weak definition) there may still be
+      // optimizations which essentially speculate based on the definition and
+      // a way to check that the specific definition is in fact the one being
+      // used. For example, this could be done by moving the weak definition to
+      // a strong (internal) definition and making the weak definition be an
+      // alias. Then a test of the address of the weak function against the new
+      // strong definition's address would be an effective way to determine the
+      // safety of optimizing a direct call edge.
+      if (!F->isDeclaration() && CalleeSet.insert(F))
+          Callees.push_back(F);
+      continue;
+    }
+
+    for (User::value_op_iterator OI = C->value_op_begin(),
+                                 OE = C->value_op_end();
+         OI != OE; ++OI)
+      if (Visited.insert(cast<Constant>(*OI)))
+        Worklist.push_back(cast<Constant>(*OI));
+  }
+}
+
+LazyCallGraph::Node::Node(LazyCallGraph &G, Function &F) : G(G), F(F) {
+  SmallVector<Constant *, 16> Worklist;
+  SmallPtrSet<Constant *, 16> Visited;
+  // Find all the potential callees in this function. First walk the
+  // instructions and add every operand which is a constant to the worklist.
+  for (Function::iterator BBI = F.begin(), BBE = F.end(); BBI != BBE; ++BBI)
+    for (BasicBlock::iterator II = BBI->begin(), IE = BBI->end(); II != IE;
+         ++II)
+      for (User::value_op_iterator OI = II->value_op_begin(),
+                                   OE = II->value_op_end();
+           OI != OE; ++OI)
+        if (Constant *C = dyn_cast<Constant>(*OI))
+          if (Visited.insert(C))
+            Worklist.push_back(C);
+
+  // We've collected all the constant (and thus potentially function or
+  // function containing) operands to all of the instructions in the function.
+  // Process them (recursively) collecting every function found.
+  findCallees(Worklist, Visited, Callees, CalleeSet);
+}
+
+LazyCallGraph::Node::Node(LazyCallGraph &G, const Node &OtherN)
+    : G(G), F(OtherN.F), CalleeSet(OtherN.CalleeSet) {
+  // Loop over the other node's callees, adding the Function*s to our list
+  // directly, and recursing to add the Node*s.
+  Callees.reserve(OtherN.Callees.size());
+  for (NodeVectorImplT::iterator OI = OtherN.Callees.begin(),
+                                 OE = OtherN.Callees.end();
+       OI != OE; ++OI)
+    if (Function *Callee = OI->dyn_cast<Function *>())
+      Callees.push_back(Callee);
+    else
+      Callees.push_back(G.copyInto(*OI->get<Node *>()));
+}
+
+#if LLVM_HAS_RVALUE_REFERENCES
+LazyCallGraph::Node::Node(LazyCallGraph &G, Node &&OtherN)
+    : G(G), F(OtherN.F), Callees(std::move(OtherN.Callees)),
+      CalleeSet(std::move(OtherN.CalleeSet)) {
+  // Loop over our Callees. They've been moved from another node, but we need
+  // to move the Node*s to live under our bump ptr allocator.
+  for (NodeVectorImplT::iterator CI = Callees.begin(), CE = Callees.end();
+       CI != CE; ++CI)
+    if (Node *ChildN = CI->dyn_cast<Node *>())
+      *CI = G.moveInto(std::move(*ChildN));
+}
+#endif
+
+LazyCallGraph::LazyCallGraph(Module &M) : M(M) {
+  for (Module::iterator FI = M.begin(), FE = M.end(); FI != FE; ++FI)
+    if (!FI->isDeclaration() && !FI->hasLocalLinkage())
+      if (EntryNodeSet.insert(&*FI))
+        EntryNodes.push_back(&*FI);
+
+  // Now add entry nodes for functions reachable via initializers to globals.
+  SmallVector<Constant *, 16> Worklist;
+  SmallPtrSet<Constant *, 16> Visited;
+  for (Module::global_iterator GI = M.global_begin(), GE = M.global_end(); GI != GE; ++GI)
+    if (GI->hasInitializer())
+      if (Visited.insert(GI->getInitializer()))
+        Worklist.push_back(GI->getInitializer());
+
+  findCallees(Worklist, Visited, EntryNodes, EntryNodeSet);
+}
+
+LazyCallGraph::LazyCallGraph(const LazyCallGraph &G)
+    : M(G.M), EntryNodeSet(G.EntryNodeSet) {
+  EntryNodes.reserve(EntryNodes.size());
+  for (NodeVectorImplT::iterator EI = EntryNodes.begin(),
+                                 EE = EntryNodes.end();
+       EI != EE; ++EI)
+    if (Function *Callee = EI->dyn_cast<Function *>())
+      EntryNodes.push_back(Callee);
+    else
+      EntryNodes.push_back(copyInto(*EI->get<Node *>()));
+}
+
+#if LLVM_HAS_RVALUE_REFERENCES
+// FIXME: This would be crazy simpler if BumpPtrAllocator were movable without
+// invalidating any of the allocated memory. We should make that be the case at
+// some point and delete this.
+LazyCallGraph::LazyCallGraph(LazyCallGraph &&G)
+    : M(G.M), EntryNodes(std::move(G.EntryNodes)),
+      EntryNodeSet(std::move(G.EntryNodeSet)) {
+  // Loop over our EntryNodes. They've been moved from another graph, but we
+  // need to move the Node*s to live under our bump ptr allocator.
+  for (NodeVectorImplT::iterator EI = EntryNodes.begin(), EE = EntryNodes.end();
+       EI != EE; ++EI)
+    if (Node *EntryN = EI->dyn_cast<Node *>())
+      *EI = G.moveInto(std::move(*EntryN));
+}
+#endif
+
+LazyCallGraph::Node *LazyCallGraph::insertInto(Function &F, Node *&MappedN) {
+  return new (MappedN = BPA.Allocate()) Node(*this, F);
+}
+
+LazyCallGraph::Node *LazyCallGraph::copyInto(const Node &OtherN) {
+  Node *&N = NodeMap[&OtherN.F];
+  if (N)
+    return N;
+
+  return new (N = BPA.Allocate()) Node(*this, OtherN);
+}
+
+#if LLVM_HAS_RVALUE_REFERENCES
+LazyCallGraph::Node *LazyCallGraph::moveInto(Node &&OtherN) {
+  Node *&N = NodeMap[&OtherN.F];
+  if (N)
+    return N;
+
+  return new (N = BPA.Allocate()) Node(*this, std::move(OtherN));
+}
+#endif
+
+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::iterator I = N.begin(), E = N.end(); I != E; ++I)
+    if (Printed.insert(*I))
+      printNodes(OS, **I, 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";
+}
+
+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::iterator I = G.begin(), E = G.end(); I != E; ++I)
+    if (Printed.insert(*I))
+      printNodes(OS, **I, Printed);
+
+  return PreservedAnalyses::all();
+}