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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/DerivedTypes.h"
20 #include "llvm/IR/Instructions.h"
21 #include "llvm/IR/Module.h"
22 #include "llvm/IR/Value.h"
23 #include "llvm/IR/ValueHandle.h"
24 #include "llvm/MC/MCContext.h"
25 #include "llvm/MC/MCSymbol.h"
26 #include "llvm/Pass.h"
27 #include "llvm/Support/Casting.h"
28 #include "llvm/Support/ErrorHandling.h"
29 #include "llvm/Target/TargetLoweringObjectFile.h"
30 #include "llvm/Target/TargetMachine.h"
31 #include <algorithm>
32 #include <cassert>
33 #include <memory>
34 #include <utility>
35 #include <vector>
36 
37 using namespace llvm;
38 using namespace llvm::dwarf;
39 
40 // Handle the Pass registration stuff necessary to use DataLayout's.
41 INITIALIZE_PASS(MachineModuleInfo, "machinemoduleinfo",
42                 "Machine Module Information", false, false)
43 char MachineModuleInfo::ID = 0;
44 
45 // Out of line virtual method.
46 MachineModuleInfoImpl::~MachineModuleInfoImpl() = default;
47 
48 namespace llvm {
49 
50 class MMIAddrLabelMapCallbackPtr final : CallbackVH {
51   MMIAddrLabelMap *Map = nullptr;
52 
53 public:
54   MMIAddrLabelMapCallbackPtr() = default;
MMIAddrLabelMapCallbackPtr(Value * V)55   MMIAddrLabelMapCallbackPtr(Value *V) : CallbackVH(V) {}
56 
setPtr(BasicBlock * BB)57   void setPtr(BasicBlock *BB) {
58     ValueHandleBase::operator=(BB);
59   }
60 
setMap(MMIAddrLabelMap * map)61   void setMap(MMIAddrLabelMap *map) { Map = map; }
62 
63   void deleted() override;
64   void allUsesReplacedWith(Value *V2) override;
65 };
66 
67 class MMIAddrLabelMap {
68   MCContext &Context;
69   struct AddrLabelSymEntry {
70     /// The symbols for the label.
71     TinyPtrVector<MCSymbol *> Symbols;
72 
73     Function *Fn;   // The containing function of the BasicBlock.
74     unsigned Index; // The index in BBCallbacks for the BasicBlock.
75   };
76 
77   DenseMap<AssertingVH<BasicBlock>, AddrLabelSymEntry> AddrLabelSymbols;
78 
79   /// Callbacks for the BasicBlock's that we have entries for.  We use this so
80   /// we get notified if a block is deleted or RAUWd.
81   std::vector<MMIAddrLabelMapCallbackPtr> BBCallbacks;
82 
83   /// This is a per-function list of symbols whose corresponding BasicBlock got
84   /// deleted.  These symbols need to be emitted at some point in the file, so
85   /// AsmPrinter emits them after the function body.
86   DenseMap<AssertingVH<Function>, std::vector<MCSymbol*>>
87     DeletedAddrLabelsNeedingEmission;
88 
89 public:
MMIAddrLabelMap(MCContext & context)90   MMIAddrLabelMap(MCContext &context) : Context(context) {}
91 
~MMIAddrLabelMap()92   ~MMIAddrLabelMap() {
93     assert(DeletedAddrLabelsNeedingEmission.empty() &&
94            "Some labels for deleted blocks never got emitted");
95   }
96 
97   ArrayRef<MCSymbol *> getAddrLabelSymbolToEmit(BasicBlock *BB);
98 
99   void takeDeletedSymbolsForFunction(Function *F,
100                                      std::vector<MCSymbol*> &Result);
101 
102   void UpdateForDeletedBlock(BasicBlock *BB);
103   void UpdateForRAUWBlock(BasicBlock *Old, BasicBlock *New);
104 };
105 
106 } // end namespace llvm
107 
getAddrLabelSymbolToEmit(BasicBlock * BB)108 ArrayRef<MCSymbol *> MMIAddrLabelMap::getAddrLabelSymbolToEmit(BasicBlock *BB) {
109   assert(BB->hasAddressTaken() &&
110          "Shouldn't get label for block without address taken");
111   AddrLabelSymEntry &Entry = AddrLabelSymbols[BB];
112 
113   // If we already had an entry for this block, just return it.
114   if (!Entry.Symbols.empty()) {
115     assert(BB->getParent() == Entry.Fn && "Parent changed");
116     return Entry.Symbols;
117   }
118 
119   // Otherwise, this is a new entry, create a new symbol for it and add an
120   // entry to BBCallbacks so we can be notified if the BB is deleted or RAUWd.
121   BBCallbacks.emplace_back(BB);
122   BBCallbacks.back().setMap(this);
123   Entry.Index = BBCallbacks.size() - 1;
124   Entry.Fn = BB->getParent();
125   Entry.Symbols.push_back(Context.createTempSymbol());
126   return Entry.Symbols;
127 }
128 
129 /// If we have any deleted symbols for F, return them.
130 void MMIAddrLabelMap::
takeDeletedSymbolsForFunction(Function * F,std::vector<MCSymbol * > & Result)131 takeDeletedSymbolsForFunction(Function *F, std::vector<MCSymbol*> &Result) {
132   DenseMap<AssertingVH<Function>, std::vector<MCSymbol*>>::iterator I =
133     DeletedAddrLabelsNeedingEmission.find(F);
134 
135   // If there are no entries for the function, just return.
136   if (I == DeletedAddrLabelsNeedingEmission.end()) return;
137 
138   // Otherwise, take the list.
139   std::swap(Result, I->second);
140   DeletedAddrLabelsNeedingEmission.erase(I);
141 }
142 
UpdateForDeletedBlock(BasicBlock * BB)143 void MMIAddrLabelMap::UpdateForDeletedBlock(BasicBlock *BB) {
144   // If the block got deleted, there is no need for the symbol.  If the symbol
145   // was already emitted, we can just forget about it, otherwise we need to
146   // queue it up for later emission when the function is output.
147   AddrLabelSymEntry Entry = std::move(AddrLabelSymbols[BB]);
148   AddrLabelSymbols.erase(BB);
149   assert(!Entry.Symbols.empty() && "Didn't have a symbol, why a callback?");
150   BBCallbacks[Entry.Index] = nullptr;  // Clear the callback.
151 
152   assert((BB->getParent() == nullptr || BB->getParent() == Entry.Fn) &&
153          "Block/parent mismatch");
154 
155   for (MCSymbol *Sym : Entry.Symbols) {
156     if (Sym->isDefined())
157       return;
158 
159     // If the block is not yet defined, we need to emit it at the end of the
160     // function.  Add the symbol to the DeletedAddrLabelsNeedingEmission list
161     // for the containing Function.  Since the block is being deleted, its
162     // parent may already be removed, we have to get the function from 'Entry'.
163     DeletedAddrLabelsNeedingEmission[Entry.Fn].push_back(Sym);
164   }
165 }
166 
UpdateForRAUWBlock(BasicBlock * Old,BasicBlock * New)167 void MMIAddrLabelMap::UpdateForRAUWBlock(BasicBlock *Old, BasicBlock *New) {
168   // Get the entry for the RAUW'd block and remove it from our map.
169   AddrLabelSymEntry OldEntry = std::move(AddrLabelSymbols[Old]);
170   AddrLabelSymbols.erase(Old);
171   assert(!OldEntry.Symbols.empty() && "Didn't have a symbol, why a callback?");
172 
173   AddrLabelSymEntry &NewEntry = AddrLabelSymbols[New];
174 
175   // If New is not address taken, just move our symbol over to it.
176   if (NewEntry.Symbols.empty()) {
177     BBCallbacks[OldEntry.Index].setPtr(New);    // Update the callback.
178     NewEntry = std::move(OldEntry);             // Set New's entry.
179     return;
180   }
181 
182   BBCallbacks[OldEntry.Index] = nullptr;    // Update the callback.
183 
184   // Otherwise, we need to add the old symbols to the new block's set.
185   NewEntry.Symbols.insert(NewEntry.Symbols.end(), OldEntry.Symbols.begin(),
186                           OldEntry.Symbols.end());
187 }
188 
deleted()189 void MMIAddrLabelMapCallbackPtr::deleted() {
190   Map->UpdateForDeletedBlock(cast<BasicBlock>(getValPtr()));
191 }
192 
allUsesReplacedWith(Value * V2)193 void MMIAddrLabelMapCallbackPtr::allUsesReplacedWith(Value *V2) {
194   Map->UpdateForRAUWBlock(cast<BasicBlock>(getValPtr()), cast<BasicBlock>(V2));
195 }
196 
MachineModuleInfo(const TargetMachine * TM)197 MachineModuleInfo::MachineModuleInfo(const TargetMachine *TM)
198   : ImmutablePass(ID), TM(*TM),
199     Context(TM->getMCAsmInfo(), TM->getMCRegisterInfo(),
200             TM->getObjFileLowering(), nullptr, false) {
201   initializeMachineModuleInfoPass(*PassRegistry::getPassRegistry());
202 }
203 
204 MachineModuleInfo::~MachineModuleInfo() = default;
205 
doInitialization(Module & M)206 bool MachineModuleInfo::doInitialization(Module &M) {
207   ObjFileMMI = nullptr;
208   CurCallSite = 0;
209   DbgInfoAvailable = UsesVAFloatArgument = UsesMorestackAddr = false;
210   HasSplitStack = HasNosplitStack = false;
211   AddrLabelSymbols = nullptr;
212   TheModule = &M;
213   return false;
214 }
215 
doFinalization(Module & M)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 *>
getAddrLabelSymbolToEmit(const BasicBlock * BB)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::
takeDeletedSymbolsForFunction(const Function * F,std::vector<MCSymbol * > & Result)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 
addPersonality(const Function * Personality)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 *
getMachineFunction(const Function & F) const262 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 &
getOrCreateMachineFunction(const Function & F)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     const TargetSubtargetInfo &STI = *TM.getSubtargetImpl(F);
280     MF = new MachineFunction(F, TM, STI, NextFnNum++, *this);
281     // Update the set entry.
282     I.first->second.reset(MF);
283   } else {
284     MF = I.first->second.get();
285   }
286 
287   LastRequest = &F;
288   LastResult = MF;
289   return *MF;
290 }
291 
deleteMachineFunctionFor(Function & F)292 void MachineModuleInfo::deleteMachineFunctionFor(Function &F) {
293   MachineFunctions.erase(&F);
294   LastRequest = nullptr;
295   LastResult = nullptr;
296 }
297 
298 namespace {
299 
300 /// This pass frees the MachineFunction object associated with a Function.
301 class FreeMachineFunction : public FunctionPass {
302 public:
303   static char ID;
304 
FreeMachineFunction()305   FreeMachineFunction() : FunctionPass(ID) {}
306 
getAnalysisUsage(AnalysisUsage & AU) const307   void getAnalysisUsage(AnalysisUsage &AU) const override {
308     AU.addRequired<MachineModuleInfo>();
309     AU.addPreserved<MachineModuleInfo>();
310   }
311 
runOnFunction(Function & F)312   bool runOnFunction(Function &F) override {
313     MachineModuleInfo &MMI = getAnalysis<MachineModuleInfo>();
314     MMI.deleteMachineFunctionFor(F);
315     return true;
316   }
317 
getPassName() const318   StringRef getPassName() const override {
319     return "Free MachineFunction";
320   }
321 };
322 
323 } // end anonymous namespace
324 
325 char FreeMachineFunction::ID;
326 
createFreeMachineFunctionPass()327 FunctionPass *llvm::createFreeMachineFunctionPass() {
328   return new FreeMachineFunction();
329 }
330 
331 //===- MMI building helpers -----------------------------------------------===//
332 
computeUsesVAFloatArgument(const CallInst & I,MachineModuleInfo & MMI)333 void llvm::computeUsesVAFloatArgument(const CallInst &I,
334                                       MachineModuleInfo &MMI) {
335   FunctionType *FT =
336       cast<FunctionType>(I.getCalledValue()->getType()->getContainedType(0));
337   if (FT->isVarArg() && !MMI.usesVAFloatArgument()) {
338     for (unsigned i = 0, e = I.getNumArgOperands(); i != e; ++i) {
339       Type *T = I.getArgOperand(i)->getType();
340       for (auto i : post_order(T)) {
341         if (i->isFloatingPointTy()) {
342           MMI.setUsesVAFloatArgument(true);
343           return;
344         }
345       }
346     }
347   }
348 }
349