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