1//===-- llvm/CodeGen/MachineModuleInfo.cpp ----------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "llvm/CodeGen/MachineModuleInfo.h"
10#include "llvm/ADT/ArrayRef.h"
11#include "llvm/ADT/DenseMap.h"
12#include "llvm/ADT/PostOrderIterator.h"
13#include "llvm/ADT/StringRef.h"
14#include "llvm/ADT/TinyPtrVector.h"
15#include "llvm/CodeGen/MachineFunction.h"
16#include "llvm/CodeGen/Passes.h"
17#include "llvm/IR/BasicBlock.h"
18#include "llvm/IR/DerivedTypes.h"
19#include "llvm/IR/Instructions.h"
20#include "llvm/IR/Module.h"
21#include "llvm/IR/Value.h"
22#include "llvm/IR/ValueHandle.h"
23#include "llvm/InitializePasses.h"
24#include "llvm/MC/MCContext.h"
25#include "llvm/MC/MCSymbol.h"
26#include "llvm/MC/MCSymbolXCOFF.h"
27#include "llvm/Pass.h"
28#include "llvm/Support/Casting.h"
29#include "llvm/Support/ErrorHandling.h"
30#include "llvm/Target/TargetLoweringObjectFile.h"
31#include "llvm/Target/TargetMachine.h"
32#include <algorithm>
33#include <cassert>
34#include <memory>
35#include <utility>
36#include <vector>
37
38using namespace llvm;
39using namespace llvm::dwarf;
40
41// Out of line virtual method.
42MachineModuleInfoImpl::~MachineModuleInfoImpl() = default;
43
44namespace llvm {
45
46class MMIAddrLabelMapCallbackPtr final : CallbackVH {
47  MMIAddrLabelMap *Map = nullptr;
48
49public:
50  MMIAddrLabelMapCallbackPtr() = default;
51  MMIAddrLabelMapCallbackPtr(Value *V) : CallbackVH(V) {}
52
53  void setPtr(BasicBlock *BB) {
54    ValueHandleBase::operator=(BB);
55  }
56
57  void setMap(MMIAddrLabelMap *map) { Map = map; }
58
59  void deleted() override;
60  void allUsesReplacedWith(Value *V2) override;
61};
62
63class MMIAddrLabelMap {
64  MCContext &Context;
65  struct AddrLabelSymEntry {
66    /// The symbols for the label.
67    TinyPtrVector<MCSymbol *> Symbols;
68
69    Function *Fn;   // The containing function of the BasicBlock.
70    unsigned Index; // The index in BBCallbacks for the BasicBlock.
71  };
72
73  DenseMap<AssertingVH<BasicBlock>, AddrLabelSymEntry> AddrLabelSymbols;
74
75  /// Callbacks for the BasicBlock's that we have entries for.  We use this so
76  /// we get notified if a block is deleted or RAUWd.
77  std::vector<MMIAddrLabelMapCallbackPtr> BBCallbacks;
78
79  /// This is a per-function list of symbols whose corresponding BasicBlock got
80  /// deleted.  These symbols need to be emitted at some point in the file, so
81  /// AsmPrinter emits them after the function body.
82  DenseMap<AssertingVH<Function>, std::vector<MCSymbol*>>
83    DeletedAddrLabelsNeedingEmission;
84
85public:
86  MMIAddrLabelMap(MCContext &context) : Context(context) {}
87
88  ~MMIAddrLabelMap() {
89    assert(DeletedAddrLabelsNeedingEmission.empty() &&
90           "Some labels for deleted blocks never got emitted");
91  }
92
93  ArrayRef<MCSymbol *> getAddrLabelSymbolToEmit(BasicBlock *BB);
94
95  void takeDeletedSymbolsForFunction(Function *F,
96                                     std::vector<MCSymbol*> &Result);
97
98  void UpdateForDeletedBlock(BasicBlock *BB);
99  void UpdateForRAUWBlock(BasicBlock *Old, BasicBlock *New);
100};
101
102} // end namespace llvm
103
104ArrayRef<MCSymbol *> MMIAddrLabelMap::getAddrLabelSymbolToEmit(BasicBlock *BB) {
105  assert(BB->hasAddressTaken() &&
106         "Shouldn't get label for block without address taken");
107  AddrLabelSymEntry &Entry = AddrLabelSymbols[BB];
108
109  // If we already had an entry for this block, just return it.
110  if (!Entry.Symbols.empty()) {
111    assert(BB->getParent() == Entry.Fn && "Parent changed");
112    return Entry.Symbols;
113  }
114
115  // Otherwise, this is a new entry, create a new symbol for it and add an
116  // entry to BBCallbacks so we can be notified if the BB is deleted or RAUWd.
117  BBCallbacks.emplace_back(BB);
118  BBCallbacks.back().setMap(this);
119  Entry.Index = BBCallbacks.size() - 1;
120  Entry.Fn = BB->getParent();
121  MCSymbol *Sym = Context.createTempSymbol(!BB->hasAddressTaken());
122  if (Context.getObjectFileInfo()->getTargetTriple().isOSBinFormatXCOFF()) {
123    MCSymbol *FnEntryPointSym =
124        Context.lookupSymbol("." + Entry.Fn->getName());
125    assert(FnEntryPointSym && "The function entry pointer symbol should have"
126		              " already been initialized.");
127    MCSectionXCOFF *Csect =
128        cast<MCSymbolXCOFF>(FnEntryPointSym)->getContainingCsect();
129    cast<MCSymbolXCOFF>(Sym)->setContainingCsect(Csect);
130  }
131  Entry.Symbols.push_back(Sym);
132  return Entry.Symbols;
133}
134
135/// If we have any deleted symbols for F, return them.
136void MMIAddrLabelMap::
137takeDeletedSymbolsForFunction(Function *F, std::vector<MCSymbol*> &Result) {
138  DenseMap<AssertingVH<Function>, std::vector<MCSymbol*>>::iterator I =
139    DeletedAddrLabelsNeedingEmission.find(F);
140
141  // If there are no entries for the function, just return.
142  if (I == DeletedAddrLabelsNeedingEmission.end()) return;
143
144  // Otherwise, take the list.
145  std::swap(Result, I->second);
146  DeletedAddrLabelsNeedingEmission.erase(I);
147}
148
149void MMIAddrLabelMap::UpdateForDeletedBlock(BasicBlock *BB) {
150  // If the block got deleted, there is no need for the symbol.  If the symbol
151  // was already emitted, we can just forget about it, otherwise we need to
152  // queue it up for later emission when the function is output.
153  AddrLabelSymEntry Entry = std::move(AddrLabelSymbols[BB]);
154  AddrLabelSymbols.erase(BB);
155  assert(!Entry.Symbols.empty() && "Didn't have a symbol, why a callback?");
156  BBCallbacks[Entry.Index] = nullptr;  // Clear the callback.
157
158  assert((BB->getParent() == nullptr || BB->getParent() == Entry.Fn) &&
159         "Block/parent mismatch");
160
161  for (MCSymbol *Sym : Entry.Symbols) {
162    if (Sym->isDefined())
163      return;
164
165    // If the block is not yet defined, we need to emit it at the end of the
166    // function.  Add the symbol to the DeletedAddrLabelsNeedingEmission list
167    // for the containing Function.  Since the block is being deleted, its
168    // parent may already be removed, we have to get the function from 'Entry'.
169    DeletedAddrLabelsNeedingEmission[Entry.Fn].push_back(Sym);
170  }
171}
172
173void MMIAddrLabelMap::UpdateForRAUWBlock(BasicBlock *Old, BasicBlock *New) {
174  // Get the entry for the RAUW'd block and remove it from our map.
175  AddrLabelSymEntry OldEntry = std::move(AddrLabelSymbols[Old]);
176  AddrLabelSymbols.erase(Old);
177  assert(!OldEntry.Symbols.empty() && "Didn't have a symbol, why a callback?");
178
179  AddrLabelSymEntry &NewEntry = AddrLabelSymbols[New];
180
181  // If New is not address taken, just move our symbol over to it.
182  if (NewEntry.Symbols.empty()) {
183    BBCallbacks[OldEntry.Index].setPtr(New);    // Update the callback.
184    NewEntry = std::move(OldEntry);             // Set New's entry.
185    return;
186  }
187
188  BBCallbacks[OldEntry.Index] = nullptr;    // Update the callback.
189
190  // Otherwise, we need to add the old symbols to the new block's set.
191  NewEntry.Symbols.insert(NewEntry.Symbols.end(), OldEntry.Symbols.begin(),
192                          OldEntry.Symbols.end());
193}
194
195void MMIAddrLabelMapCallbackPtr::deleted() {
196  Map->UpdateForDeletedBlock(cast<BasicBlock>(getValPtr()));
197}
198
199void MMIAddrLabelMapCallbackPtr::allUsesReplacedWith(Value *V2) {
200  Map->UpdateForRAUWBlock(cast<BasicBlock>(getValPtr()), cast<BasicBlock>(V2));
201}
202
203void MachineModuleInfo::initialize() {
204  ObjFileMMI = nullptr;
205  CurCallSite = 0;
206  UsesMSVCFloatingPoint = UsesMorestackAddr = false;
207  HasSplitStack = HasNosplitStack = false;
208  AddrLabelSymbols = nullptr;
209}
210
211void MachineModuleInfo::finalize() {
212  Personalities.clear();
213
214  delete AddrLabelSymbols;
215  AddrLabelSymbols = nullptr;
216
217  Context.reset();
218
219  delete ObjFileMMI;
220  ObjFileMMI = nullptr;
221}
222
223MachineModuleInfo::MachineModuleInfo(MachineModuleInfo &&MMI)
224    : TM(std::move(MMI.TM)),
225      Context(MMI.TM.getMCAsmInfo(), MMI.TM.getMCRegisterInfo(),
226              MMI.TM.getObjFileLowering(), nullptr, nullptr, false) {
227  ObjFileMMI = MMI.ObjFileMMI;
228  CurCallSite = MMI.CurCallSite;
229  UsesMSVCFloatingPoint = MMI.UsesMSVCFloatingPoint;
230  UsesMorestackAddr = MMI.UsesMorestackAddr;
231  HasSplitStack = MMI.HasSplitStack;
232  HasNosplitStack = MMI.HasNosplitStack;
233  AddrLabelSymbols = MMI.AddrLabelSymbols;
234  TheModule = MMI.TheModule;
235}
236
237MachineModuleInfo::MachineModuleInfo(const LLVMTargetMachine *TM)
238    : TM(*TM), Context(TM->getMCAsmInfo(), TM->getMCRegisterInfo(),
239                       TM->getObjFileLowering(), nullptr, nullptr, false) {
240  initialize();
241}
242
243MachineModuleInfo::~MachineModuleInfo() { finalize(); }
244
245//===- Address of Block Management ----------------------------------------===//
246
247ArrayRef<MCSymbol *>
248MachineModuleInfo::getAddrLabelSymbolToEmit(const BasicBlock *BB) {
249  // Lazily create AddrLabelSymbols.
250  if (!AddrLabelSymbols)
251    AddrLabelSymbols = new MMIAddrLabelMap(Context);
252 return AddrLabelSymbols->getAddrLabelSymbolToEmit(const_cast<BasicBlock*>(BB));
253}
254
255void MachineModuleInfo::
256takeDeletedSymbolsForFunction(const Function *F,
257                              std::vector<MCSymbol*> &Result) {
258  // If no blocks have had their addresses taken, we're done.
259  if (!AddrLabelSymbols) return;
260  return AddrLabelSymbols->
261     takeDeletedSymbolsForFunction(const_cast<Function*>(F), Result);
262}
263
264/// \name Exception Handling
265/// \{
266
267void MachineModuleInfo::addPersonality(const Function *Personality) {
268  for (unsigned i = 0; i < Personalities.size(); ++i)
269    if (Personalities[i] == Personality)
270      return;
271  Personalities.push_back(Personality);
272}
273
274/// \}
275
276MachineFunction *
277MachineModuleInfo::getMachineFunction(const Function &F) const {
278  auto I = MachineFunctions.find(&F);
279  return I != MachineFunctions.end() ? I->second.get() : nullptr;
280}
281
282MachineFunction &
283MachineModuleInfo::getOrCreateMachineFunction(const Function &F) {
284  // Shortcut for the common case where a sequence of MachineFunctionPasses
285  // all query for the same Function.
286  if (LastRequest == &F)
287    return *LastResult;
288
289  auto I = MachineFunctions.insert(
290      std::make_pair(&F, std::unique_ptr<MachineFunction>()));
291  MachineFunction *MF;
292  if (I.second) {
293    // No pre-existing machine function, create a new one.
294    const TargetSubtargetInfo &STI = *TM.getSubtargetImpl(F);
295    MF = new MachineFunction(F, TM, STI, NextFnNum++, *this);
296    // Update the set entry.
297    I.first->second.reset(MF);
298  } else {
299    MF = I.first->second.get();
300  }
301
302  LastRequest = &F;
303  LastResult = MF;
304  return *MF;
305}
306
307void MachineModuleInfo::deleteMachineFunctionFor(Function &F) {
308  MachineFunctions.erase(&F);
309  LastRequest = nullptr;
310  LastResult = nullptr;
311}
312
313namespace {
314
315/// This pass frees the MachineFunction object associated with a Function.
316class FreeMachineFunction : public FunctionPass {
317public:
318  static char ID;
319
320  FreeMachineFunction() : FunctionPass(ID) {}
321
322  void getAnalysisUsage(AnalysisUsage &AU) const override {
323    AU.addRequired<MachineModuleInfoWrapperPass>();
324    AU.addPreserved<MachineModuleInfoWrapperPass>();
325  }
326
327  bool runOnFunction(Function &F) override {
328    MachineModuleInfo &MMI =
329        getAnalysis<MachineModuleInfoWrapperPass>().getMMI();
330    MMI.deleteMachineFunctionFor(F);
331    return true;
332  }
333
334  StringRef getPassName() const override {
335    return "Free MachineFunction";
336  }
337};
338
339} // end anonymous namespace
340
341char FreeMachineFunction::ID;
342
343FunctionPass *llvm::createFreeMachineFunctionPass() {
344  return new FreeMachineFunction();
345}
346
347MachineModuleInfoWrapperPass::MachineModuleInfoWrapperPass(
348    const LLVMTargetMachine *TM)
349    : ImmutablePass(ID), MMI(TM) {
350  initializeMachineModuleInfoWrapperPassPass(*PassRegistry::getPassRegistry());
351}
352
353// Handle the Pass registration stuff necessary to use DataLayout's.
354INITIALIZE_PASS(MachineModuleInfoWrapperPass, "machinemoduleinfo",
355                "Machine Module Information", false, false)
356char MachineModuleInfoWrapperPass::ID = 0;
357
358bool MachineModuleInfoWrapperPass::doInitialization(Module &M) {
359  MMI.initialize();
360  MMI.TheModule = &M;
361  MMI.DbgInfoAvailable = !M.debug_compile_units().empty();
362  return false;
363}
364
365bool MachineModuleInfoWrapperPass::doFinalization(Module &M) {
366  MMI.finalize();
367  return false;
368}
369
370AnalysisKey MachineModuleAnalysis::Key;
371
372MachineModuleInfo MachineModuleAnalysis::run(Module &M,
373                                             ModuleAnalysisManager &) {
374  MachineModuleInfo MMI(TM);
375  MMI.TheModule = &M;
376  MMI.DbgInfoAvailable = !M.debug_compile_units().empty();
377  return MMI;
378}
379