MachineModuleInfo.cpp revision ecb436f195e55e6bf84713b54efd6c621a9ddbfe 
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
12#include "llvm/Constants.h"
13#include "llvm/Analysis/ValueTracking.h"
14#include "llvm/CodeGen/MachineFunctionPass.h"
15#include "llvm/CodeGen/MachineFunction.h"
16#include "llvm/CodeGen/Passes.h"
17#include "llvm/Target/TargetInstrInfo.h"
18#include "llvm/Target/TargetMachine.h"
19#include "llvm/Target/TargetOptions.h"
20#include "llvm/DerivedTypes.h"
21#include "llvm/GlobalVariable.h"
22#include "llvm/Intrinsics.h"
23#include "llvm/Instructions.h"
24#include "llvm/Module.h"
25#include "llvm/Support/Dwarf.h"
26#include "llvm/Support/ErrorHandling.h"
27#include "llvm/Support/Streams.h"
28using namespace llvm;
29using namespace llvm::dwarf;
30
31// Handle the Pass registration stuff necessary to use TargetData's.
32static RegisterPass<MachineModuleInfo>
33X("machinemoduleinfo", "Module Information");
34char MachineModuleInfo::ID = 0;
35
36//===----------------------------------------------------------------------===//
37
38MachineModuleInfo::MachineModuleInfo()
39: ImmutablePass(&ID)
40, LabelIDList()
41, FrameMoves()
42, LandingPads()
43, Personalities()
44, CallsEHReturn(0)
45, CallsUnwindInit(0)
46, DbgInfoAvailable(false)
47{
48  // Always emit "no personality" info
49  Personalities.push_back(NULL);
50}
51MachineModuleInfo::~MachineModuleInfo() {
52
53}
54
55/// doInitialization - Initialize the state for a new module.
56///
57bool MachineModuleInfo::doInitialization() {
58  return false;
59}
60
61/// doFinalization - Tear down the state after completion of a module.
62///
63bool MachineModuleInfo::doFinalization() {
64  return false;
65}
66
67/// BeginFunction - Begin gathering function meta information.
68///
69void MachineModuleInfo::BeginFunction(MachineFunction *MF) {
70  // Coming soon.
71}
72
73/// EndFunction - Discard function meta information.
74///
75void MachineModuleInfo::EndFunction() {
76  // Clean up frame info.
77  FrameMoves.clear();
78
79  // Clean up exception info.
80  LandingPads.clear();
81  TypeInfos.clear();
82  FilterIds.clear();
83  FilterEnds.clear();
84  CallsEHReturn = 0;
85  CallsUnwindInit = 0;
86}
87
88/// AnalyzeModule - Scan the module for global debug information.
89///
90void MachineModuleInfo::AnalyzeModule(Module &M) {
91  // Insert functions in the llvm.used array (but not llvm.compiler.used) into
92  // UsedFunctions.
93  GlobalVariable *GV = M.getGlobalVariable("llvm.used");
94  if (!GV || !GV->hasInitializer()) return;
95
96  // Should be an array of 'i8*'.
97  ConstantArray *InitList = dyn_cast<ConstantArray>(GV->getInitializer());
98  if (InitList == 0) return;
99
100  for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i)
101    if (Function *F =
102          dyn_cast<Function>(InitList->getOperand(i)->stripPointerCasts()))
103      UsedFunctions.insert(F);
104}
105
106//===-EH-------------------------------------------------------------------===//
107
108/// getOrCreateLandingPadInfo - Find or create an LandingPadInfo for the
109/// specified MachineBasicBlock.
110LandingPadInfo &MachineModuleInfo::getOrCreateLandingPadInfo
111    (MachineBasicBlock *LandingPad) {
112  unsigned N = LandingPads.size();
113  for (unsigned i = 0; i < N; ++i) {
114    LandingPadInfo &LP = LandingPads[i];
115    if (LP.LandingPadBlock == LandingPad)
116      return LP;
117  }
118
119  LandingPads.push_back(LandingPadInfo(LandingPad));
120  return LandingPads[N];
121}
122
123/// addInvoke - Provide the begin and end labels of an invoke style call and
124/// associate it with a try landing pad block.
125void MachineModuleInfo::addInvoke(MachineBasicBlock *LandingPad,
126                                  unsigned BeginLabel, unsigned EndLabel) {
127  LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
128  LP.BeginLabels.push_back(BeginLabel);
129  LP.EndLabels.push_back(EndLabel);
130}
131
132/// addLandingPad - Provide the label of a try LandingPad block.
133///
134unsigned MachineModuleInfo::addLandingPad(MachineBasicBlock *LandingPad) {
135  unsigned LandingPadLabel = NextLabelID();
136  LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
137  LP.LandingPadLabel = LandingPadLabel;
138  return LandingPadLabel;
139}
140
141/// addPersonality - Provide the personality function for the exception
142/// information.
143void MachineModuleInfo::addPersonality(MachineBasicBlock *LandingPad,
144                                       Function *Personality) {
145  LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
146  LP.Personality = Personality;
147
148  for (unsigned i = 0; i < Personalities.size(); ++i)
149    if (Personalities[i] == Personality)
150      return;
151
152  Personalities.push_back(Personality);
153}
154
155/// addCatchTypeInfo - Provide the catch typeinfo for a landing pad.
156///
157void MachineModuleInfo::addCatchTypeInfo(MachineBasicBlock *LandingPad,
158                                        std::vector<GlobalVariable *> &TyInfo) {
159  LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
160  for (unsigned N = TyInfo.size(); N; --N)
161    LP.TypeIds.push_back(getTypeIDFor(TyInfo[N - 1]));
162}
163
164/// addFilterTypeInfo - Provide the filter typeinfo for a landing pad.
165///
166void MachineModuleInfo::addFilterTypeInfo(MachineBasicBlock *LandingPad,
167                                        std::vector<GlobalVariable *> &TyInfo) {
168  LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
169  std::vector<unsigned> IdsInFilter(TyInfo.size());
170  for (unsigned I = 0, E = TyInfo.size(); I != E; ++I)
171    IdsInFilter[I] = getTypeIDFor(TyInfo[I]);
172  LP.TypeIds.push_back(getFilterIDFor(IdsInFilter));
173}
174
175/// addCleanup - Add a cleanup action for a landing pad.
176///
177void MachineModuleInfo::addCleanup(MachineBasicBlock *LandingPad) {
178  LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
179  LP.TypeIds.push_back(0);
180}
181
182/// TidyLandingPads - Remap landing pad labels and remove any deleted landing
183/// pads.
184void MachineModuleInfo::TidyLandingPads() {
185  for (unsigned i = 0; i != LandingPads.size(); ) {
186    LandingPadInfo &LandingPad = LandingPads[i];
187    LandingPad.LandingPadLabel = MappedLabel(LandingPad.LandingPadLabel);
188
189    // Special case: we *should* emit LPs with null LP MBB. This indicates
190    // "nounwind" case.
191    if (!LandingPad.LandingPadLabel && LandingPad.LandingPadBlock) {
192      LandingPads.erase(LandingPads.begin() + i);
193      continue;
194    }
195
196    for (unsigned j=0; j != LandingPads[i].BeginLabels.size(); ) {
197      unsigned BeginLabel = MappedLabel(LandingPad.BeginLabels[j]);
198      unsigned EndLabel = MappedLabel(LandingPad.EndLabels[j]);
199
200      if (!BeginLabel || !EndLabel) {
201        LandingPad.BeginLabels.erase(LandingPad.BeginLabels.begin() + j);
202        LandingPad.EndLabels.erase(LandingPad.EndLabels.begin() + j);
203        continue;
204      }
205
206      LandingPad.BeginLabels[j] = BeginLabel;
207      LandingPad.EndLabels[j] = EndLabel;
208      ++j;
209    }
210
211    // Remove landing pads with no try-ranges.
212    if (LandingPads[i].BeginLabels.empty()) {
213      LandingPads.erase(LandingPads.begin() + i);
214      continue;
215    }
216
217    // If there is no landing pad, ensure that the list of typeids is empty.
218    // If the only typeid is a cleanup, this is the same as having no typeids.
219    if (!LandingPad.LandingPadBlock ||
220        (LandingPad.TypeIds.size() == 1 && !LandingPad.TypeIds[0]))
221      LandingPad.TypeIds.clear();
222
223    ++i;
224  }
225}
226
227/// getTypeIDFor - Return the type id for the specified typeinfo.  This is
228/// function wide.
229unsigned MachineModuleInfo::getTypeIDFor(GlobalVariable *TI) {
230  for (unsigned i = 0, N = TypeInfos.size(); i != N; ++i)
231    if (TypeInfos[i] == TI) return i + 1;
232
233  TypeInfos.push_back(TI);
234  return TypeInfos.size();
235}
236
237/// getFilterIDFor - Return the filter id for the specified typeinfos.  This is
238/// function wide.
239int MachineModuleInfo::getFilterIDFor(std::vector<unsigned> &TyIds) {
240  // If the new filter coincides with the tail of an existing filter, then
241  // re-use the existing filter.  Folding filters more than this requires
242  // re-ordering filters and/or their elements - probably not worth it.
243  for (std::vector<unsigned>::iterator I = FilterEnds.begin(),
244       E = FilterEnds.end(); I != E; ++I) {
245    unsigned i = *I, j = TyIds.size();
246
247    while (i && j)
248      if (FilterIds[--i] != TyIds[--j])
249        goto try_next;
250
251    if (!j)
252      // The new filter coincides with range [i, end) of the existing filter.
253      return -(1 + i);
254
255try_next:;
256  }
257
258  // Add the new filter.
259  int FilterID = -(1 + FilterIds.size());
260  FilterIds.reserve(FilterIds.size() + TyIds.size() + 1);
261  for (unsigned I = 0, N = TyIds.size(); I != N; ++I)
262    FilterIds.push_back(TyIds[I]);
263  FilterEnds.push_back(FilterIds.size());
264  FilterIds.push_back(0); // terminator
265  return FilterID;
266}
267
268/// getPersonality - Return the personality function for the current function.
269Function *MachineModuleInfo::getPersonality() const {
270  // FIXME: Until PR1414 will be fixed, we're using 1 personality function per
271  // function
272  return !LandingPads.empty() ? LandingPads[0].Personality : NULL;
273}
274
275/// getPersonalityIndex - Return unique index for current personality
276/// function. NULL personality function should always get zero index.
277unsigned MachineModuleInfo::getPersonalityIndex() const {
278  const Function* Personality = NULL;
279
280  // Scan landing pads. If there is at least one non-NULL personality - use it.
281  for (unsigned i = 0; i != LandingPads.size(); ++i)
282    if (LandingPads[i].Personality) {
283      Personality = LandingPads[i].Personality;
284      break;
285    }
286
287  for (unsigned i = 0; i < Personalities.size(); ++i) {
288    if (Personalities[i] == Personality)
289      return i;
290  }
291
292  // This should never happen
293  llvm_unreachable("Personality function should be set!");
294  return 0;
295}
296
297//===----------------------------------------------------------------------===//
298/// DebugLabelFolding pass - This pass prunes out redundant labels.  This allows
299/// a info consumer to determine if the range of two labels is empty, by seeing
300/// if the labels map to the same reduced label.
301
302namespace llvm {
303
304struct DebugLabelFolder : public MachineFunctionPass {
305  static char ID;
306  DebugLabelFolder() : MachineFunctionPass(&ID) {}
307
308  virtual void getAnalysisUsage(AnalysisUsage &AU) const {
309    AU.setPreservesCFG();
310    AU.addPreservedID(MachineLoopInfoID);
311    AU.addPreservedID(MachineDominatorsID);
312    MachineFunctionPass::getAnalysisUsage(AU);
313  }
314
315  virtual bool runOnMachineFunction(MachineFunction &MF);
316  virtual const char *getPassName() const { return "Label Folder"; }
317};
318
319char DebugLabelFolder::ID = 0;
320
321bool DebugLabelFolder::runOnMachineFunction(MachineFunction &MF) {
322  // Get machine module info.
323  MachineModuleInfo *MMI = getAnalysisIfAvailable<MachineModuleInfo>();
324  if (!MMI) return false;
325
326  // Track if change is made.
327  bool MadeChange = false;
328  // No prior label to begin.
329  unsigned PriorLabel = 0;
330
331  // Iterate through basic blocks.
332  for (MachineFunction::iterator BB = MF.begin(), E = MF.end();
333       BB != E; ++BB) {
334    // Iterate through instructions.
335    for (MachineBasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) {
336      // Is it a label.
337      if (I->isDebugLabel() && !MMI->isDbgLabelUsed(I->getOperand(0).getImm())){
338        // The label ID # is always operand #0, an immediate.
339        unsigned NextLabel = I->getOperand(0).getImm();
340
341        // If there was an immediate prior label.
342        if (PriorLabel) {
343          // Remap the current label to prior label.
344          MMI->RemapLabel(NextLabel, PriorLabel);
345          // Delete the current label.
346          I = BB->erase(I);
347          // Indicate a change has been made.
348          MadeChange = true;
349          continue;
350        } else {
351          // Start a new round.
352          PriorLabel = NextLabel;
353        }
354       } else {
355        // No consecutive labels.
356        PriorLabel = 0;
357      }
358
359      ++I;
360    }
361  }
362
363  return MadeChange;
364}
365
366FunctionPass *createDebugLabelFoldingPass() { return new DebugLabelFolder(); }
367
368}
369
370