AutoUpgrade.cpp revision cd81d94322a39503e4a3e87b6ee03d4fcb3465fb 
1//===-- AutoUpgrade.cpp - Implement auto-upgrade helper functions ---------===//
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// This file implements the auto-upgrade helper functions
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/IR/AutoUpgrade.h"
15#include "llvm/IR/CFG.h"
16#include "llvm/IR/CallSite.h"
17#include "llvm/IR/Constants.h"
18#include "llvm/IR/DebugInfo.h"
19#include "llvm/IR/DiagnosticInfo.h"
20#include "llvm/IR/Function.h"
21#include "llvm/IR/IRBuilder.h"
22#include "llvm/IR/Instruction.h"
23#include "llvm/IR/IntrinsicInst.h"
24#include "llvm/IR/LLVMContext.h"
25#include "llvm/IR/Module.h"
26#include "llvm/Support/ErrorHandling.h"
27#include <cstring>
28using namespace llvm;
29
30// Upgrade the declarations of the SSE4.1 functions whose arguments have
31// changed their type from v4f32 to v2i64.
32static bool UpgradeSSE41Function(Function* F, Intrinsic::ID IID,
33                                 Function *&NewFn) {
34  // Check whether this is an old version of the function, which received
35  // v4f32 arguments.
36  Type *Arg0Type = F->getFunctionType()->getParamType(0);
37  if (Arg0Type != VectorType::get(Type::getFloatTy(F->getContext()), 4))
38    return false;
39
40  // Yes, it's old, replace it with new version.
41  F->setName(F->getName() + ".old");
42  NewFn = Intrinsic::getDeclaration(F->getParent(), IID);
43  return true;
44}
45
46static bool UpgradeIntrinsicFunction1(Function *F, Function *&NewFn) {
47  assert(F && "Illegal to upgrade a non-existent Function.");
48
49  // Quickly eliminate it, if it's not a candidate.
50  StringRef Name = F->getName();
51  if (Name.size() <= 8 || !Name.startswith("llvm."))
52    return false;
53  Name = Name.substr(5); // Strip off "llvm."
54
55  switch (Name[0]) {
56  default: break;
57  case 'a': {
58    if (Name.startswith("arm.neon.vclz")) {
59      Type* args[2] = {
60        F->arg_begin()->getType(),
61        Type::getInt1Ty(F->getContext())
62      };
63      // Can't use Intrinsic::getDeclaration here as it adds a ".i1" to
64      // the end of the name. Change name from llvm.arm.neon.vclz.* to
65      //  llvm.ctlz.*
66      FunctionType* fType = FunctionType::get(F->getReturnType(), args, false);
67      NewFn = Function::Create(fType, F->getLinkage(),
68                               "llvm.ctlz." + Name.substr(14), F->getParent());
69      return true;
70    }
71    if (Name.startswith("arm.neon.vcnt")) {
72      NewFn = Intrinsic::getDeclaration(F->getParent(), Intrinsic::ctpop,
73                                        F->arg_begin()->getType());
74      return true;
75    }
76    break;
77  }
78  case 'c': {
79    if (Name.startswith("ctlz.") && F->arg_size() == 1) {
80      F->setName(Name + ".old");
81      NewFn = Intrinsic::getDeclaration(F->getParent(), Intrinsic::ctlz,
82                                        F->arg_begin()->getType());
83      return true;
84    }
85    if (Name.startswith("cttz.") && F->arg_size() == 1) {
86      F->setName(Name + ".old");
87      NewFn = Intrinsic::getDeclaration(F->getParent(), Intrinsic::cttz,
88                                        F->arg_begin()->getType());
89      return true;
90    }
91    break;
92  }
93  case 'o':
94    // We only need to change the name to match the mangling including the
95    // address space.
96    if (F->arg_size() == 2 && Name.startswith("objectsize.")) {
97      Type *Tys[2] = { F->getReturnType(), F->arg_begin()->getType() };
98      if (F->getName() != Intrinsic::getName(Intrinsic::objectsize, Tys)) {
99        F->setName(Name + ".old");
100        NewFn = Intrinsic::getDeclaration(F->getParent(),
101                                          Intrinsic::objectsize, Tys);
102        return true;
103      }
104    }
105    break;
106
107  case 'x': {
108    if (Name.startswith("x86.sse2.pcmpeq.") ||
109        Name.startswith("x86.sse2.pcmpgt.") ||
110        Name.startswith("x86.avx2.pcmpeq.") ||
111        Name.startswith("x86.avx2.pcmpgt.") ||
112        Name.startswith("x86.avx.vpermil.") ||
113        Name == "x86.avx.movnt.dq.256" ||
114        Name == "x86.avx.movnt.pd.256" ||
115        Name == "x86.avx.movnt.ps.256" ||
116        Name == "x86.sse42.crc32.64.8" ||
117        Name == "x86.avx.vbroadcast.ss" ||
118        Name == "x86.avx.vbroadcast.ss.256" ||
119        Name == "x86.avx.vbroadcast.sd.256" ||
120        (Name.startswith("x86.xop.vpcom") && F->arg_size() == 2)) {
121      NewFn = nullptr;
122      return true;
123    }
124    // SSE4.1 ptest functions may have an old signature.
125    if (Name.startswith("x86.sse41.ptest")) {
126      if (Name == "x86.sse41.ptestc")
127        return UpgradeSSE41Function(F, Intrinsic::x86_sse41_ptestc, NewFn);
128      if (Name == "x86.sse41.ptestz")
129        return UpgradeSSE41Function(F, Intrinsic::x86_sse41_ptestz, NewFn);
130      if (Name == "x86.sse41.ptestnzc")
131        return UpgradeSSE41Function(F, Intrinsic::x86_sse41_ptestnzc, NewFn);
132    }
133    // frcz.ss/sd may need to have an argument dropped
134    if (Name.startswith("x86.xop.vfrcz.ss") && F->arg_size() == 2) {
135      F->setName(Name + ".old");
136      NewFn = Intrinsic::getDeclaration(F->getParent(),
137                                        Intrinsic::x86_xop_vfrcz_ss);
138      return true;
139    }
140    if (Name.startswith("x86.xop.vfrcz.sd") && F->arg_size() == 2) {
141      F->setName(Name + ".old");
142      NewFn = Intrinsic::getDeclaration(F->getParent(),
143                                        Intrinsic::x86_xop_vfrcz_sd);
144      return true;
145    }
146    // Fix the FMA4 intrinsics to remove the 4
147    if (Name.startswith("x86.fma4.")) {
148      F->setName("llvm.x86.fma" + Name.substr(8));
149      NewFn = F;
150      return true;
151    }
152    break;
153  }
154  }
155
156  //  This may not belong here. This function is effectively being overloaded
157  //  to both detect an intrinsic which needs upgrading, and to provide the
158  //  upgraded form of the intrinsic. We should perhaps have two separate
159  //  functions for this.
160  return false;
161}
162
163bool llvm::UpgradeIntrinsicFunction(Function *F, Function *&NewFn) {
164  NewFn = nullptr;
165  bool Upgraded = UpgradeIntrinsicFunction1(F, NewFn);
166
167  // Upgrade intrinsic attributes.  This does not change the function.
168  if (NewFn)
169    F = NewFn;
170  if (unsigned id = F->getIntrinsicID())
171    F->setAttributes(Intrinsic::getAttributes(F->getContext(),
172                                              (Intrinsic::ID)id));
173  return Upgraded;
174}
175
176static bool UpgradeGlobalStructors(GlobalVariable *GV) {
177  ArrayType *ATy = dyn_cast<ArrayType>(GV->getType()->getElementType());
178  StructType *OldTy =
179      ATy ? dyn_cast<StructType>(ATy->getElementType()) : nullptr;
180
181  // Only upgrade an array of a two field struct with the appropriate field
182  // types.
183  if (!OldTy || OldTy->getNumElements() != 2)
184    return false;
185
186  // Get the upgraded 3 element type.
187  PointerType *VoidPtrTy = Type::getInt8Ty(GV->getContext())->getPointerTo();
188  Type *Tys[3] = {
189    OldTy->getElementType(0),
190    OldTy->getElementType(1),
191    VoidPtrTy
192  };
193  StructType *NewTy =
194      StructType::get(GV->getContext(), Tys, /*isPacked=*/false);
195
196  // Build new constants with a null third field filled in.
197  Constant *OldInitC = GV->getInitializer();
198  ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC);
199  if (!OldInit && !isa<ConstantAggregateZero>(OldInitC))
200    return false;
201  std::vector<Constant *> Initializers;
202  if (OldInit) {
203    for (Use &U : OldInit->operands()) {
204      ConstantStruct *Init = cast<ConstantStruct>(&U);
205      Constant *NewInit =
206        ConstantStruct::get(NewTy, Init->getOperand(0), Init->getOperand(1),
207                            Constant::getNullValue(VoidPtrTy), nullptr);
208      Initializers.push_back(NewInit);
209    }
210  }
211  assert(Initializers.size() == ATy->getNumElements());
212
213  // Replace the old GV with a new one.
214  ATy = ArrayType::get(NewTy, Initializers.size());
215  Constant *NewInit = ConstantArray::get(ATy, Initializers);
216  GlobalVariable *NewGV = new GlobalVariable(
217      *GV->getParent(), ATy, GV->isConstant(), GV->getLinkage(), NewInit, "",
218      GV, GV->getThreadLocalMode(), GV->getType()->getAddressSpace(),
219      GV->isExternallyInitialized());
220  NewGV->copyAttributesFrom(GV);
221  NewGV->takeName(GV);
222  assert(GV->use_empty() && "program cannot use initializer list");
223  GV->eraseFromParent();
224  return true;
225}
226
227bool llvm::UpgradeGlobalVariable(GlobalVariable *GV) {
228  if (GV->getName() == "llvm.global_ctors" ||
229      GV->getName() == "llvm.global_dtors")
230    return UpgradeGlobalStructors(GV);
231
232  // Nothing to do yet.
233  return false;
234}
235
236// UpgradeIntrinsicCall - Upgrade a call to an old intrinsic to be a call the
237// upgraded intrinsic. All argument and return casting must be provided in
238// order to seamlessly integrate with existing context.
239void llvm::UpgradeIntrinsicCall(CallInst *CI, Function *NewFn) {
240  Function *F = CI->getCalledFunction();
241  LLVMContext &C = CI->getContext();
242  IRBuilder<> Builder(C);
243  Builder.SetInsertPoint(CI->getParent(), CI);
244
245  assert(F && "Intrinsic call is not direct?");
246
247  if (!NewFn) {
248    // Get the Function's name.
249    StringRef Name = F->getName();
250
251    Value *Rep;
252    // Upgrade packed integer vector compares intrinsics to compare instructions
253    if (Name.startswith("llvm.x86.sse2.pcmpeq.") ||
254        Name.startswith("llvm.x86.avx2.pcmpeq.")) {
255      Rep = Builder.CreateICmpEQ(CI->getArgOperand(0), CI->getArgOperand(1),
256                                 "pcmpeq");
257      // need to sign extend since icmp returns vector of i1
258      Rep = Builder.CreateSExt(Rep, CI->getType(), "");
259    } else if (Name.startswith("llvm.x86.sse2.pcmpgt.") ||
260               Name.startswith("llvm.x86.avx2.pcmpgt.")) {
261      Rep = Builder.CreateICmpSGT(CI->getArgOperand(0), CI->getArgOperand(1),
262                                  "pcmpgt");
263      // need to sign extend since icmp returns vector of i1
264      Rep = Builder.CreateSExt(Rep, CI->getType(), "");
265    } else if (Name == "llvm.x86.avx.movnt.dq.256" ||
266               Name == "llvm.x86.avx.movnt.ps.256" ||
267               Name == "llvm.x86.avx.movnt.pd.256") {
268      IRBuilder<> Builder(C);
269      Builder.SetInsertPoint(CI->getParent(), CI);
270
271      Module *M = F->getParent();
272      SmallVector<Value *, 1> Elts;
273      Elts.push_back(ConstantInt::get(Type::getInt32Ty(C), 1));
274      MDNode *Node = MDNode::get(C, Elts);
275
276      Value *Arg0 = CI->getArgOperand(0);
277      Value *Arg1 = CI->getArgOperand(1);
278
279      // Convert the type of the pointer to a pointer to the stored type.
280      Value *BC = Builder.CreateBitCast(Arg0,
281                                        PointerType::getUnqual(Arg1->getType()),
282                                        "cast");
283      StoreInst *SI = Builder.CreateStore(Arg1, BC);
284      SI->setMetadata(M->getMDKindID("nontemporal"), Node);
285      SI->setAlignment(16);
286
287      // Remove intrinsic.
288      CI->eraseFromParent();
289      return;
290    } else if (Name.startswith("llvm.x86.xop.vpcom")) {
291      Intrinsic::ID intID;
292      if (Name.endswith("ub"))
293        intID = Intrinsic::x86_xop_vpcomub;
294      else if (Name.endswith("uw"))
295        intID = Intrinsic::x86_xop_vpcomuw;
296      else if (Name.endswith("ud"))
297        intID = Intrinsic::x86_xop_vpcomud;
298      else if (Name.endswith("uq"))
299        intID = Intrinsic::x86_xop_vpcomuq;
300      else if (Name.endswith("b"))
301        intID = Intrinsic::x86_xop_vpcomb;
302      else if (Name.endswith("w"))
303        intID = Intrinsic::x86_xop_vpcomw;
304      else if (Name.endswith("d"))
305        intID = Intrinsic::x86_xop_vpcomd;
306      else if (Name.endswith("q"))
307        intID = Intrinsic::x86_xop_vpcomq;
308      else
309        llvm_unreachable("Unknown suffix");
310
311      Name = Name.substr(18); // strip off "llvm.x86.xop.vpcom"
312      unsigned Imm;
313      if (Name.startswith("lt"))
314        Imm = 0;
315      else if (Name.startswith("le"))
316        Imm = 1;
317      else if (Name.startswith("gt"))
318        Imm = 2;
319      else if (Name.startswith("ge"))
320        Imm = 3;
321      else if (Name.startswith("eq"))
322        Imm = 4;
323      else if (Name.startswith("ne"))
324        Imm = 5;
325      else if (Name.startswith("true"))
326        Imm = 6;
327      else if (Name.startswith("false"))
328        Imm = 7;
329      else
330        llvm_unreachable("Unknown condition");
331
332      Function *VPCOM = Intrinsic::getDeclaration(F->getParent(), intID);
333      Rep = Builder.CreateCall3(VPCOM, CI->getArgOperand(0),
334                                CI->getArgOperand(1), Builder.getInt8(Imm));
335    } else if (Name == "llvm.x86.sse42.crc32.64.8") {
336      Function *CRC32 = Intrinsic::getDeclaration(F->getParent(),
337                                               Intrinsic::x86_sse42_crc32_32_8);
338      Value *Trunc0 = Builder.CreateTrunc(CI->getArgOperand(0), Type::getInt32Ty(C));
339      Rep = Builder.CreateCall2(CRC32, Trunc0, CI->getArgOperand(1));
340      Rep = Builder.CreateZExt(Rep, CI->getType(), "");
341    } else if (Name.startswith("llvm.x86.avx.vbroadcast")) {
342      // Replace broadcasts with a series of insertelements.
343      Type *VecTy = CI->getType();
344      Type *EltTy = VecTy->getVectorElementType();
345      unsigned EltNum = VecTy->getVectorNumElements();
346      Value *Cast = Builder.CreateBitCast(CI->getArgOperand(0),
347                                          EltTy->getPointerTo());
348      Value *Load = Builder.CreateLoad(Cast);
349      Type *I32Ty = Type::getInt32Ty(C);
350      Rep = UndefValue::get(VecTy);
351      for (unsigned I = 0; I < EltNum; ++I)
352        Rep = Builder.CreateInsertElement(Rep, Load,
353                                          ConstantInt::get(I32Ty, I));
354    } else {
355      bool PD128 = false, PD256 = false, PS128 = false, PS256 = false;
356      if (Name == "llvm.x86.avx.vpermil.pd.256")
357        PD256 = true;
358      else if (Name == "llvm.x86.avx.vpermil.pd")
359        PD128 = true;
360      else if (Name == "llvm.x86.avx.vpermil.ps.256")
361        PS256 = true;
362      else if (Name == "llvm.x86.avx.vpermil.ps")
363        PS128 = true;
364
365      if (PD256 || PD128 || PS256 || PS128) {
366        Value *Op0 = CI->getArgOperand(0);
367        unsigned Imm = cast<ConstantInt>(CI->getArgOperand(1))->getZExtValue();
368        SmallVector<Constant*, 8> Idxs;
369
370        if (PD128)
371          for (unsigned i = 0; i != 2; ++i)
372            Idxs.push_back(Builder.getInt32((Imm >> i) & 0x1));
373        else if (PD256)
374          for (unsigned l = 0; l != 4; l+=2)
375            for (unsigned i = 0; i != 2; ++i)
376              Idxs.push_back(Builder.getInt32(((Imm >> (l+i)) & 0x1) + l));
377        else if (PS128)
378          for (unsigned i = 0; i != 4; ++i)
379            Idxs.push_back(Builder.getInt32((Imm >> (2 * i)) & 0x3));
380        else if (PS256)
381          for (unsigned l = 0; l != 8; l+=4)
382            for (unsigned i = 0; i != 4; ++i)
383              Idxs.push_back(Builder.getInt32(((Imm >> (2 * i)) & 0x3) + l));
384        else
385          llvm_unreachable("Unexpected function");
386
387        Rep = Builder.CreateShuffleVector(Op0, Op0, ConstantVector::get(Idxs));
388      } else {
389        llvm_unreachable("Unknown function for CallInst upgrade.");
390      }
391    }
392
393    CI->replaceAllUsesWith(Rep);
394    CI->eraseFromParent();
395    return;
396  }
397
398  std::string Name = CI->getName().str();
399  CI->setName(Name + ".old");
400
401  switch (NewFn->getIntrinsicID()) {
402  default:
403    llvm_unreachable("Unknown function for CallInst upgrade.");
404
405  case Intrinsic::ctlz:
406  case Intrinsic::cttz:
407    assert(CI->getNumArgOperands() == 1 &&
408           "Mismatch between function args and call args");
409    CI->replaceAllUsesWith(Builder.CreateCall2(NewFn, CI->getArgOperand(0),
410                                               Builder.getFalse(), Name));
411    CI->eraseFromParent();
412    return;
413
414  case Intrinsic::objectsize:
415    CI->replaceAllUsesWith(Builder.CreateCall2(NewFn,
416                                               CI->getArgOperand(0),
417                                               CI->getArgOperand(1),
418                                               Name));
419    CI->eraseFromParent();
420    return;
421
422  case Intrinsic::arm_neon_vclz: {
423    // Change name from llvm.arm.neon.vclz.* to llvm.ctlz.*
424    CI->replaceAllUsesWith(Builder.CreateCall2(NewFn, CI->getArgOperand(0),
425                                               Builder.getFalse(),
426                                               "llvm.ctlz." + Name.substr(14)));
427    CI->eraseFromParent();
428    return;
429  }
430  case Intrinsic::ctpop: {
431    CI->replaceAllUsesWith(Builder.CreateCall(NewFn, CI->getArgOperand(0)));
432    CI->eraseFromParent();
433    return;
434  }
435
436  case Intrinsic::x86_xop_vfrcz_ss:
437  case Intrinsic::x86_xop_vfrcz_sd:
438    CI->replaceAllUsesWith(Builder.CreateCall(NewFn, CI->getArgOperand(1),
439                                              Name));
440    CI->eraseFromParent();
441    return;
442
443  case Intrinsic::x86_sse41_ptestc:
444  case Intrinsic::x86_sse41_ptestz:
445  case Intrinsic::x86_sse41_ptestnzc: {
446    // The arguments for these intrinsics used to be v4f32, and changed
447    // to v2i64. This is purely a nop, since those are bitwise intrinsics.
448    // So, the only thing required is a bitcast for both arguments.
449    // First, check the arguments have the old type.
450    Value *Arg0 = CI->getArgOperand(0);
451    if (Arg0->getType() != VectorType::get(Type::getFloatTy(C), 4))
452      return;
453
454    // Old intrinsic, add bitcasts
455    Value *Arg1 = CI->getArgOperand(1);
456
457    Value *BC0 =
458      Builder.CreateBitCast(Arg0,
459                            VectorType::get(Type::getInt64Ty(C), 2),
460                            "cast");
461    Value *BC1 =
462      Builder.CreateBitCast(Arg1,
463                            VectorType::get(Type::getInt64Ty(C), 2),
464                            "cast");
465
466    CallInst* NewCall = Builder.CreateCall2(NewFn, BC0, BC1, Name);
467    CI->replaceAllUsesWith(NewCall);
468    CI->eraseFromParent();
469    return;
470  }
471  }
472}
473
474// This tests each Function to determine if it needs upgrading. When we find
475// one we are interested in, we then upgrade all calls to reflect the new
476// function.
477void llvm::UpgradeCallsToIntrinsic(Function* F) {
478  assert(F && "Illegal attempt to upgrade a non-existent intrinsic.");
479
480  // Upgrade the function and check if it is a totaly new function.
481  Function *NewFn;
482  if (UpgradeIntrinsicFunction(F, NewFn)) {
483    if (NewFn != F) {
484      // Replace all uses to the old function with the new one if necessary.
485      for (Value::user_iterator UI = F->user_begin(), UE = F->user_end();
486           UI != UE; ) {
487        if (CallInst *CI = dyn_cast<CallInst>(*UI++))
488          UpgradeIntrinsicCall(CI, NewFn);
489      }
490      // Remove old function, no longer used, from the module.
491      F->eraseFromParent();
492    }
493  }
494}
495
496void llvm::UpgradeInstWithTBAATag(Instruction *I) {
497  MDNode *MD = I->getMetadata(LLVMContext::MD_tbaa);
498  assert(MD && "UpgradeInstWithTBAATag should have a TBAA tag");
499  // Check if the tag uses struct-path aware TBAA format.
500  if (isa<MDNode>(MD->getOperand(0)) && MD->getNumOperands() >= 3)
501    return;
502
503  if (MD->getNumOperands() == 3) {
504    Value *Elts[] = {
505      MD->getOperand(0),
506      MD->getOperand(1)
507    };
508    MDNode *ScalarType = MDNode::get(I->getContext(), Elts);
509    // Create a MDNode <ScalarType, ScalarType, offset 0, const>
510    Value *Elts2[] = {
511      ScalarType, ScalarType,
512      Constant::getNullValue(Type::getInt64Ty(I->getContext())),
513      MD->getOperand(2)
514    };
515    I->setMetadata(LLVMContext::MD_tbaa, MDNode::get(I->getContext(), Elts2));
516  } else {
517    // Create a MDNode <MD, MD, offset 0>
518    Value *Elts[] = {MD, MD,
519      Constant::getNullValue(Type::getInt64Ty(I->getContext()))};
520    I->setMetadata(LLVMContext::MD_tbaa, MDNode::get(I->getContext(), Elts));
521  }
522}
523
524Instruction *llvm::UpgradeBitCastInst(unsigned Opc, Value *V, Type *DestTy,
525                                      Instruction *&Temp) {
526  if (Opc != Instruction::BitCast)
527    return nullptr;
528
529  Temp = nullptr;
530  Type *SrcTy = V->getType();
531  if (SrcTy->isPtrOrPtrVectorTy() && DestTy->isPtrOrPtrVectorTy() &&
532      SrcTy->getPointerAddressSpace() != DestTy->getPointerAddressSpace()) {
533    LLVMContext &Context = V->getContext();
534
535    // We have no information about target data layout, so we assume that
536    // the maximum pointer size is 64bit.
537    Type *MidTy = Type::getInt64Ty(Context);
538    Temp = CastInst::Create(Instruction::PtrToInt, V, MidTy);
539
540    return CastInst::Create(Instruction::IntToPtr, Temp, DestTy);
541  }
542
543  return nullptr;
544}
545
546Value *llvm::UpgradeBitCastExpr(unsigned Opc, Constant *C, Type *DestTy) {
547  if (Opc != Instruction::BitCast)
548    return nullptr;
549
550  Type *SrcTy = C->getType();
551  if (SrcTy->isPtrOrPtrVectorTy() && DestTy->isPtrOrPtrVectorTy() &&
552      SrcTy->getPointerAddressSpace() != DestTy->getPointerAddressSpace()) {
553    LLVMContext &Context = C->getContext();
554
555    // We have no information about target data layout, so we assume that
556    // the maximum pointer size is 64bit.
557    Type *MidTy = Type::getInt64Ty(Context);
558
559    return ConstantExpr::getIntToPtr(ConstantExpr::getPtrToInt(C, MidTy),
560                                     DestTy);
561  }
562
563  return nullptr;
564}
565
566/// Check the debug info version number, if it is out-dated, drop the debug
567/// info. Return true if module is modified.
568bool llvm::UpgradeDebugInfo(Module &M) {
569  unsigned Version = getDebugMetadataVersionFromModule(M);
570  if (Version == DEBUG_METADATA_VERSION)
571    return false;
572
573  bool RetCode = StripDebugInfo(M);
574  if (RetCode) {
575    DiagnosticInfoDebugMetadataVersion DiagVersion(M, Version);
576    M.getContext().diagnose(DiagVersion);
577  }
578  return RetCode;
579}
580
581void llvm::UpgradeMDStringConstant(std::string &String) {
582  const std::string OldPrefix = "llvm.vectorizer.";
583  if (String.find(OldPrefix) == 0) {
584        String.replace(0, OldPrefix.size(), "llvm.loop.vectorize.");
585  }
586}
587