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 
38 using namespace llvm;
39 using namespace llvm::dwarf;
40 
41 // Out of line virtual method.
42 MachineModuleInfoImpl::~MachineModuleInfoImpl() = default;
43 
44 namespace llvm {
45 
46 class MMIAddrLabelMapCallbackPtr final : CallbackVH {
47   MMIAddrLabelMap *Map = nullptr;
48 
49 public:
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 
63 class 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 
85 public:
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 
104 ArrayRef<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.
136 void MMIAddrLabelMap::
137 takeDeletedSymbolsForFunction(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 
149 void 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 
173 void 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 
195 void MMIAddrLabelMapCallbackPtr::deleted() {
196   Map->UpdateForDeletedBlock(cast<BasicBlock>(getValPtr()));
197 }
198 
199 void MMIAddrLabelMapCallbackPtr::allUsesReplacedWith(Value *V2) {
200   Map->UpdateForRAUWBlock(cast<BasicBlock>(getValPtr()), cast<BasicBlock>(V2));
201 }
202 
203 void MachineModuleInfo::initialize() {
204   ObjFileMMI = nullptr;
205   CurCallSite = 0;
206   UsesMSVCFloatingPoint = UsesMorestackAddr = false;
207   HasSplitStack = HasNosplitStack = false;
208   AddrLabelSymbols = nullptr;
209 }
210 
211 void 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 
223 MachineModuleInfo::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 
237 MachineModuleInfo::MachineModuleInfo(const LLVMTargetMachine *TM)
238     : TM(*TM), Context(TM->getMCAsmInfo(), TM->getMCRegisterInfo(),
239                        TM->getObjFileLowering(), nullptr, nullptr, false) {
240   initialize();
241 }
242 
243 MachineModuleInfo::~MachineModuleInfo() { finalize(); }
244 
245 //===- Address of Block Management ----------------------------------------===//
246 
247 ArrayRef<MCSymbol *>
248 MachineModuleInfo::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 
255 void MachineModuleInfo::
256 takeDeletedSymbolsForFunction(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 
267 void 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 
276 MachineFunction *
277 MachineModuleInfo::getMachineFunction(const Function &F) const {
278   auto I = MachineFunctions.find(&F);
279   return I != MachineFunctions.end() ? I->second.get() : nullptr;
280 }
281 
282 MachineFunction &
283 MachineModuleInfo::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 
307 void MachineModuleInfo::deleteMachineFunctionFor(Function &F) {
308   MachineFunctions.erase(&F);
309   LastRequest = nullptr;
310   LastResult = nullptr;
311 }
312 
313 namespace {
314 
315 /// This pass frees the MachineFunction object associated with a Function.
316 class FreeMachineFunction : public FunctionPass {
317 public:
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 
341 char FreeMachineFunction::ID;
342 
343 FunctionPass *llvm::createFreeMachineFunctionPass() {
344   return new FreeMachineFunction();
345 }
346 
347 MachineModuleInfoWrapperPass::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.
354 INITIALIZE_PASS(MachineModuleInfoWrapperPass, "machinemoduleinfo",
355                 "Machine Module Information", false, false)
356 char MachineModuleInfoWrapperPass::ID = 0;
357 
358 bool MachineModuleInfoWrapperPass::doInitialization(Module &M) {
359   MMI.initialize();
360   MMI.TheModule = &M;
361   MMI.DbgInfoAvailable = !M.debug_compile_units().empty();
362   return false;
363 }
364 
365 bool MachineModuleInfoWrapperPass::doFinalization(Module &M) {
366   MMI.finalize();
367   return false;
368 }
369 
370 AnalysisKey MachineModuleAnalysis::Key;
371 
372 MachineModuleInfo 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