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