lib/Transforms/IPO/PassManagerBuilder.cpp

   1 //===- PassManagerBuilder.cpp - Build Standard Pass -----------------------===//
   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 defines the PassManagerBuilder class, which is used to set up a
  11 // "standard" optimization sequence suitable for languages like C and C++.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15
  16 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
  17 #include "llvm-c/Transforms/PassManagerBuilder.h"
  18 #include "llvm/ADT/SmallVector.h"
  19 #include "llvm/Analysis/Passes.h"
  20 #include "llvm/IR/DataLayout.h"
  21 #include "llvm/IR/Verifier.h"
  22 #include "llvm/PassManager.h"
  23 #include "llvm/Support/CommandLine.h"
  24 #include "llvm/Support/ManagedStatic.h"
  25 #include "llvm/Target/TargetLibraryInfo.h"
  26 #include "llvm/Target/TargetMachine.h"
  27 #include "llvm/Target/TargetSubtargetInfo.h"
  28 #include "llvm/Transforms/IPO.h"
  29 #include "llvm/Transforms/Scalar.h"
  30 #include "llvm/Transforms/Vectorize.h"
  31
  32 using namespace llvm;
  33
  34 static cl::opt<bool>
  35 RunLoopVectorization("vectorize-loops", cl::Hidden,
  36                      cl::desc("Run the Loop vectorization passes"));
  37
  38 static cl::opt<bool>
  39 RunSLPVectorization("vectorize-slp", cl::Hidden,
  40                     cl::desc("Run the SLP vectorization passes"));
  41
  42 static cl::opt<bool>
  43 RunBBVectorization("vectorize-slp-aggressive", cl::Hidden,
  44                     cl::desc("Run the BB vectorization passes"));
  45
  46 static cl::opt<bool>
  47 UseGVNAfterVectorization("use-gvn-after-vectorization",
  48   cl::init(false), cl::Hidden,
  49   cl::desc("Run GVN instead of Early CSE after vectorization passes"));
  50
  51 static cl::opt<bool> UseNewSROA("use-new-sroa",
  52   cl::init(true), cl::Hidden,
  53   cl::desc("Enable the new, experimental SROA pass"));
  54
  55 static cl::opt<bool>
  56 RunLoopRerolling("reroll-loops", cl::Hidden,
  57                  cl::desc("Run the loop rerolling pass"));
  58
  59 static cl::opt<bool> RunLoadCombine("combine-loads", cl::init(false),
  60                                     cl::Hidden,
  61                                     cl::desc("Run the load combining pass"));
  62
  63 static cl::opt<bool>
  64 RunSLPAfterLoopVectorization("run-slp-after-loop-vectorization",
  65   cl::init(true), cl::Hidden,
  66   cl::desc("Run the SLP vectorizer (and BB vectorizer) after the Loop "
  67            "vectorizer instead of before"));
  68
  69 static cl::opt<bool> UseCFLAA("use-cfl-aa",
  70   cl::init(false), cl::Hidden,
  71   cl::desc("Enable the new, experimental CFL alias analysis"));
  72
  73 static cl::opt<bool>
  74 EnableMLSM("mlsm", cl::desc("Enable motion of merged load and store"),
  75            cl::init(true));
  76
  77 PassManagerBuilder::PassManagerBuilder() {
  78     OptLevel = 2;
  79     SizeLevel = 0;
  80     LibraryInfo = nullptr;
  81     Inliner = nullptr;
  82     DisableTailCalls = false;
  83     DisableUnitAtATime = false;
  84     DisableUnrollLoops = false;
  85     BBVectorize = RunBBVectorization;
  86     SLPVectorize = RunSLPVectorization;
  87     LoopVectorize = RunLoopVectorization;
  88     RerollLoops = RunLoopRerolling;
  89     LoadCombine = RunLoadCombine;
  90     DisableGVNLoadPRE = false;
  91     VerifyInput = false;
  92     VerifyOutput = false;
  93     StripDebug = false;
  94 }
  95
  96 PassManagerBuilder::~PassManagerBuilder() {
  97   delete LibraryInfo;
  98   delete Inliner;
  99 }
 100
 101 /// Set of global extensions, automatically added as part of the standard set.
 102 static ManagedStatic<SmallVector<std::pair<PassManagerBuilder::ExtensionPointTy,
 103    PassManagerBuilder::ExtensionFn>, 8> > GlobalExtensions;
 104
 105 void PassManagerBuilder::addGlobalExtension(
 106     PassManagerBuilder::ExtensionPointTy Ty,
 107     PassManagerBuilder::ExtensionFn Fn) {
 108   GlobalExtensions->push_back(std::make_pair(Ty, Fn));
 109 }
 110
 111 void PassManagerBuilder::addExtension(ExtensionPointTy Ty, ExtensionFn Fn) {
 112   Extensions.push_back(std::make_pair(Ty, Fn));
 113 }
 114
 115 void PassManagerBuilder::addExtensionsToPM(ExtensionPointTy ETy,
 116                                            PassManagerBase &PM) const {
 117   for (unsigned i = 0, e = GlobalExtensions->size(); i != e; ++i)
 118     if ((*GlobalExtensions)[i].first == ETy)
 119       (*GlobalExtensions)[i].second(*this, PM);
 120   for (unsigned i = 0, e = Extensions.size(); i != e; ++i)
 121     if (Extensions[i].first == ETy)
 122       Extensions[i].second(*this, PM);
 123 }
 124
 125 void
 126 PassManagerBuilder::addInitialAliasAnalysisPasses(PassManagerBase &PM) const {
 127   // Add TypeBasedAliasAnalysis before BasicAliasAnalysis so that
 128   // BasicAliasAnalysis wins if they disagree. This is intended to help
 129   // support "obvious" type-punning idioms.
 130   if (UseCFLAA)
 131     PM.add(createCFLAliasAnalysisPass());
 132   PM.add(createTypeBasedAliasAnalysisPass());
 133   PM.add(createScopedNoAliasAAPass());
 134   PM.add(createBasicAliasAnalysisPass());
 135 }
 136
 137 void PassManagerBuilder::populateFunctionPassManager(FunctionPassManager &FPM) {
 138   addExtensionsToPM(EP_EarlyAsPossible, FPM);
 139
 140   // Add LibraryInfo if we have some.
 141   if (LibraryInfo) FPM.add(new TargetLibraryInfo(*LibraryInfo));
 142
 143   if (OptLevel == 0) return;
 144
 145   addInitialAliasAnalysisPasses(FPM);
 146
 147   FPM.add(createCFGSimplificationPass());
 148   if (UseNewSROA)
 149     FPM.add(createSROAPass());
 150   else
 151     FPM.add(createScalarReplAggregatesPass());
 152   FPM.add(createEarlyCSEPass());
 153   FPM.add(createLowerExpectIntrinsicPass());
 154 }
 155
 156 void PassManagerBuilder::populateModulePassManager(PassManagerBase &MPM) {
 157   // If all optimizations are disabled, just run the always-inline pass.
 158   if (OptLevel == 0) {
 159     if (Inliner) {
 160       MPM.add(Inliner);
 161       Inliner = nullptr;
 162     }
 163
 164     // FIXME: This is a HACK! The inliner pass above implicitly creates a CGSCC
 165     // pass manager, but we don't want to add extensions into that pass manager.
 166     // To prevent this we must insert a no-op module pass to reset the pass
 167     // manager to get the same behavior as EP_OptimizerLast in non-O0 builds.
 168     if (!GlobalExtensions->empty() || !Extensions.empty())
 169       MPM.add(createBarrierNoopPass());
 170
 171     addExtensionsToPM(EP_EnabledOnOptLevel0, MPM);
 172     return;
 173   }
 174
 175   // Add LibraryInfo if we have some.
 176   if (LibraryInfo) MPM.add(new TargetLibraryInfo(*LibraryInfo));
 177
 178   addInitialAliasAnalysisPasses(MPM);
 179
 180   if (!DisableUnitAtATime) {
 181     addExtensionsToPM(EP_ModuleOptimizerEarly, MPM);
 182
 183     MPM.add(createIPSCCPPass());              // IP SCCP
 184     MPM.add(createGlobalOptimizerPass());     // Optimize out global vars
 185
 186     MPM.add(createDeadArgEliminationPass());  // Dead argument elimination
 187
 188     MPM.add(createInstructionCombiningPass());// Clean up after IPCP & DAE
 189     addExtensionsToPM(EP_Peephole, MPM);
 190     MPM.add(createCFGSimplificationPass());   // Clean up after IPCP & DAE
 191   }
 192
 193   // Start of CallGraph SCC passes.
 194   if (!DisableUnitAtATime)
 195     MPM.add(createPruneEHPass());             // Remove dead EH info
 196   if (Inliner) {
 197     MPM.add(Inliner);
 198     Inliner = nullptr;
 199   }
 200   if (!DisableUnitAtATime)
 201     MPM.add(createFunctionAttrsPass());       // Set readonly/readnone attrs
 202   if (OptLevel > 2)
 203     MPM.add(createArgumentPromotionPass());   // Scalarize uninlined fn args
 204
 205   // Start of function pass.
 206   // Break up aggregate allocas, using SSAUpdater.
 207   if (UseNewSROA)
 208     MPM.add(createSROAPass(/*RequiresDomTree*/ false));
 209   else
 210     MPM.add(createScalarReplAggregatesPass(-1, false));
 211   MPM.add(createEarlyCSEPass());              // Catch trivial redundancies
 212   MPM.add(createJumpThreadingPass());         // Thread jumps.
 213   MPM.add(createCorrelatedValuePropagationPass()); // Propagate conditionals
 214   MPM.add(createCFGSimplificationPass());     // Merge & remove BBs
 215   MPM.add(createInstructionCombiningPass());  // Combine silly seq's
 216   addExtensionsToPM(EP_Peephole, MPM);
 217
 218   if (!DisableTailCalls)
 219     MPM.add(createTailCallEliminationPass()); // Eliminate tail calls
 220   MPM.add(createCFGSimplificationPass());     // Merge & remove BBs
 221   MPM.add(createReassociatePass());           // Reassociate expressions
 222   MPM.add(createLoopRotatePass());            // Rotate Loop
 223   MPM.add(createLICMPass());                  // Hoist loop invariants
 224   MPM.add(createLoopUnswitchPass(SizeLevel || OptLevel < 3));
 225   MPM.add(createInstructionCombiningPass());
 226   MPM.add(createIndVarSimplifyPass());        // Canonicalize indvars
 227   MPM.add(createLoopIdiomPass());             // Recognize idioms like memset.
 228   MPM.add(createLoopDeletionPass());          // Delete dead loops
 229
 230   if (!DisableUnrollLoops)
 231     MPM.add(createSimpleLoopUnrollPass());    // Unroll small loops
 232   addExtensionsToPM(EP_LoopOptimizerEnd, MPM);
 233
 234   if (OptLevel > 1) {
 235     if (EnableMLSM)
 236       MPM.add(createMergedLoadStoreMotionPass()); // Merge ld/st in diamonds
 237     MPM.add(createGVNPass(DisableGVNLoadPRE));  // Remove redundancies
 238   }
 239   MPM.add(createMemCpyOptPass());             // Remove memcpy / form memset
 240   MPM.add(createSCCPPass());                  // Constant prop with SCCP
 241
 242   // Run instcombine after redundancy elimination to exploit opportunities
 243   // opened up by them.
 244   MPM.add(createInstructionCombiningPass());
 245   addExtensionsToPM(EP_Peephole, MPM);
 246   MPM.add(createJumpThreadingPass());         // Thread jumps
 247   MPM.add(createCorrelatedValuePropagationPass());
 248   MPM.add(createDeadStoreEliminationPass());  // Delete dead stores
 249
 250   addExtensionsToPM(EP_ScalarOptimizerLate, MPM);
 251
 252   if (RerollLoops)
 253     MPM.add(createLoopRerollPass());
 254   if (!RunSLPAfterLoopVectorization) {
 255     if (SLPVectorize)
 256       MPM.add(createSLPVectorizerPass());   // Vectorize parallel scalar chains.
 257
 258     if (BBVectorize) {
 259       MPM.add(createBBVectorizePass());
 260       MPM.add(createInstructionCombiningPass());
 261       addExtensionsToPM(EP_Peephole, MPM);
 262       if (OptLevel > 1 && UseGVNAfterVectorization)
 263         MPM.add(createGVNPass(DisableGVNLoadPRE)); // Remove redundancies
 264       else
 265         MPM.add(createEarlyCSEPass());      // Catch trivial redundancies
 266
 267       // BBVectorize may have significantly shortened a loop body; unroll again.
 268       if (!DisableUnrollLoops)
 269         MPM.add(createLoopUnrollPass());
 270     }
 271   }
 272
 273   if (LoadCombine)
 274     MPM.add(createLoadCombinePass());
 275
 276   MPM.add(createAggressiveDCEPass());         // Delete dead instructions
 277   MPM.add(createCFGSimplificationPass()); // Merge & remove BBs
 278   MPM.add(createInstructionCombiningPass());  // Clean up after everything.
 279   addExtensionsToPM(EP_Peephole, MPM);
 280
 281   // FIXME: This is a HACK! The inliner pass above implicitly creates a CGSCC
 282   // pass manager that we are specifically trying to avoid. To prevent this
 283   // we must insert a no-op module pass to reset the pass manager.
 284   MPM.add(createBarrierNoopPass());
 285   MPM.add(createLoopVectorizePass(DisableUnrollLoops, LoopVectorize));
 286   // FIXME: Because of #pragma vectorize enable, the passes below are always
 287   // inserted in the pipeline, even when the vectorizer doesn't run (ex. when
 288   // on -O1 and no #pragma is found). Would be good to have these two passes
 289   // as function calls, so that we can only pass them when the vectorizer
 290   // changed the code.
 291   MPM.add(createInstructionCombiningPass());
 292
 293   if (RunSLPAfterLoopVectorization) {
 294     if (SLPVectorize)
 295       MPM.add(createSLPVectorizerPass());   // Vectorize parallel scalar chains.
 296
 297     if (BBVectorize) {
 298       MPM.add(createBBVectorizePass());
 299       MPM.add(createInstructionCombiningPass());
 300       addExtensionsToPM(EP_Peephole, MPM);
 301       if (OptLevel > 1 && UseGVNAfterVectorization)
 302         MPM.add(createGVNPass(DisableGVNLoadPRE)); // Remove redundancies
 303       else
 304         MPM.add(createEarlyCSEPass());      // Catch trivial redundancies
 305
 306       // BBVectorize may have significantly shortened a loop body; unroll again.
 307       if (!DisableUnrollLoops)
 308         MPM.add(createLoopUnrollPass());
 309     }
 310   }
 311
 312   addExtensionsToPM(EP_Peephole, MPM);
 313   MPM.add(createCFGSimplificationPass());
 314
 315   if (!DisableUnrollLoops)
 316     MPM.add(createLoopUnrollPass());    // Unroll small loops
 317
 318   // After vectorization and unrolling, assume intrinsics may tell us more
 319   // about pointer alignments.
 320   MPM.add(createAlignmentFromAssumptionsPass());
 321
 322   if (!DisableUnitAtATime) {
 323     // FIXME: We shouldn't bother with this anymore.
 324     MPM.add(createStripDeadPrototypesPass()); // Get rid of dead prototypes
 325
 326     // GlobalOpt already deletes dead functions and globals, at -O2 try a
 327     // late pass of GlobalDCE.  It is capable of deleting dead cycles.
 328     if (OptLevel > 1) {
 329       MPM.add(createGlobalDCEPass());         // Remove dead fns and globals.
 330       MPM.add(createConstantMergePass());     // Merge dup global constants
 331     }
 332   }
 333   addExtensionsToPM(EP_OptimizerLast, MPM);
 334 }
 335
 336 void PassManagerBuilder::addLTOOptimizationPasses(PassManagerBase &PM) {
 337   // Provide AliasAnalysis services for optimizations.
 338   addInitialAliasAnalysisPasses(PM);
 339
 340   // Propagate constants at call sites into the functions they call.  This
 341   // opens opportunities for globalopt (and inlining) by substituting function
 342   // pointers passed as arguments to direct uses of functions.
 343   PM.add(createIPSCCPPass());
 344
 345   // Now that we internalized some globals, see if we can hack on them!
 346   PM.add(createGlobalOptimizerPass());
 347
 348   // Linking modules together can lead to duplicated global constants, only
 349   // keep one copy of each constant.
 350   PM.add(createConstantMergePass());
 351
 352   // Remove unused arguments from functions.
 353   PM.add(createDeadArgEliminationPass());
 354
 355   // Reduce the code after globalopt and ipsccp.  Both can open up significant
 356   // simplification opportunities, and both can propagate functions through
 357   // function pointers.  When this happens, we often have to resolve varargs
 358   // calls, etc, so let instcombine do this.
 359   PM.add(createInstructionCombiningPass());
 360   addExtensionsToPM(EP_Peephole, PM);
 361
 362   // Inline small functions
 363   bool RunInliner = Inliner;
 364   if (RunInliner) {
 365     PM.add(Inliner);
 366     Inliner = nullptr;
 367   }
 368
 369   PM.add(createPruneEHPass());   // Remove dead EH info.
 370
 371   // Optimize globals again if we ran the inliner.
 372   if (RunInliner)
 373     PM.add(createGlobalOptimizerPass());
 374   PM.add(createGlobalDCEPass()); // Remove dead functions.
 375
 376   // If we didn't decide to inline a function, check to see if we can
 377   // transform it to pass arguments by value instead of by reference.
 378   PM.add(createArgumentPromotionPass());
 379
 380   // The IPO passes may leave cruft around.  Clean up after them.
 381   PM.add(createInstructionCombiningPass());
 382   addExtensionsToPM(EP_Peephole, PM);
 383   PM.add(createJumpThreadingPass());
 384
 385   // Break up allocas
 386   if (UseNewSROA)
 387     PM.add(createSROAPass());
 388   else
 389     PM.add(createScalarReplAggregatesPass());
 390
 391   // Run a few AA driven optimizations here and now, to cleanup the code.
 392   PM.add(createFunctionAttrsPass()); // Add nocapture.
 393   PM.add(createGlobalsModRefPass()); // IP alias analysis.
 394
 395   PM.add(createLICMPass());                 // Hoist loop invariants.
 396   if (EnableMLSM)
 397     PM.add(createMergedLoadStoreMotionPass()); // Merge ld/st in diamonds.
 398   PM.add(createGVNPass(DisableGVNLoadPRE)); // Remove redundancies.
 399   PM.add(createMemCpyOptPass());            // Remove dead memcpys.
 400
 401   // Nuke dead stores.
 402   PM.add(createDeadStoreEliminationPass());
 403
 404   // More loops are countable; try to optimize them.
 405   PM.add(createIndVarSimplifyPass());
 406   PM.add(createLoopDeletionPass());
 407   PM.add(createLoopVectorizePass(true, true));
 408
 409   // More scalar chains could be vectorized due to more alias information
 410   PM.add(createSLPVectorizerPass()); // Vectorize parallel scalar chains.
 411
 412   // After vectorization, assume intrinsics may tell us more about pointer
 413   // alignments.
 414   PM.add(createAlignmentFromAssumptionsPass());
 415
 416   if (LoadCombine)
 417     PM.add(createLoadCombinePass());
 418
 419   // Cleanup and simplify the code after the scalar optimizations.
 420   PM.add(createInstructionCombiningPass());
 421   addExtensionsToPM(EP_Peephole, PM);
 422
 423   PM.add(createJumpThreadingPass());
 424
 425   // Delete basic blocks, which optimization passes may have killed.
 426   PM.add(createCFGSimplificationPass());
 427
 428   // Now that we have optimized the program, discard unreachable functions.
 429   PM.add(createGlobalDCEPass());
 430 }
 431
 432 void PassManagerBuilder::populateLTOPassManager(PassManagerBase &PM,
 433                                                 TargetMachine *TM) {
 434   if (TM) {
 435     const DataLayout *DL = TM->getSubtargetImpl()->getDataLayout();
 436     PM.add(new DataLayoutPass(*DL));
 437     TM->addAnalysisPasses(PM);
 438   }
 439
 440   if (LibraryInfo)
 441     PM.add(new TargetLibraryInfo(*LibraryInfo));
 442
 443   if (VerifyInput)
 444     PM.add(createVerifierPass());
 445
 446   if (StripDebug)
 447     PM.add(createStripSymbolsPass(true));
 448
 449   if (VerifyInput)
 450     PM.add(createDebugInfoVerifierPass());
 451
 452   if (OptLevel != 0)
 453     addLTOOptimizationPasses(PM);
 454
 455   if (VerifyOutput) {
 456     PM.add(createVerifierPass());
 457     PM.add(createDebugInfoVerifierPass());
 458   }
 459 }
 460
 461 inline PassManagerBuilder *unwrap(LLVMPassManagerBuilderRef P) {
 462     return reinterpret_cast<PassManagerBuilder*>(P);
 463 }
 464
 465 inline LLVMPassManagerBuilderRef wrap(PassManagerBuilder *P) {
 466   return reinterpret_cast<LLVMPassManagerBuilderRef>(P);
 467 }
 468
 469 LLVMPassManagerBuilderRef LLVMPassManagerBuilderCreate() {
 470   PassManagerBuilder *PMB = new PassManagerBuilder();
 471   return wrap(PMB);
 472 }
 473
 474 void LLVMPassManagerBuilderDispose(LLVMPassManagerBuilderRef PMB) {
 475   PassManagerBuilder *Builder = unwrap(PMB);
 476   delete Builder;
 477 }
 478
 479 void
 480 LLVMPassManagerBuilderSetOptLevel(LLVMPassManagerBuilderRef PMB,
 481                                   unsigned OptLevel) {
 482   PassManagerBuilder *Builder = unwrap(PMB);
 483   Builder->OptLevel = OptLevel;
 484 }
 485
 486 void
 487 LLVMPassManagerBuilderSetSizeLevel(LLVMPassManagerBuilderRef PMB,
 488                                    unsigned SizeLevel) {
 489   PassManagerBuilder *Builder = unwrap(PMB);
 490   Builder->SizeLevel = SizeLevel;
 491 }
 492
 493 void
 494 LLVMPassManagerBuilderSetDisableUnitAtATime(LLVMPassManagerBuilderRef PMB,
 495                                             LLVMBool Value) {
 496   PassManagerBuilder *Builder = unwrap(PMB);
 497   Builder->DisableUnitAtATime = Value;
 498 }
 499
 500 void
 501 LLVMPassManagerBuilderSetDisableUnrollLoops(LLVMPassManagerBuilderRef PMB,
 502                                             LLVMBool Value) {
 503   PassManagerBuilder *Builder = unwrap(PMB);
 504   Builder->DisableUnrollLoops = Value;
 505 }
 506
 507 void
 508 LLVMPassManagerBuilderSetDisableSimplifyLibCalls(LLVMPassManagerBuilderRef PMB,
 509                                                  LLVMBool Value) {
 510   // NOTE: The simplify-libcalls pass has been removed.
 511 }
 512
 513 void
 514 LLVMPassManagerBuilderUseInlinerWithThreshold(LLVMPassManagerBuilderRef PMB,
 515                                               unsigned Threshold) {
 516   PassManagerBuilder *Builder = unwrap(PMB);
 517   Builder->Inliner = createFunctionInliningPass(Threshold);
 518 }
 519
 520 void
 521 LLVMPassManagerBuilderPopulateFunctionPassManager(LLVMPassManagerBuilderRef PMB,
 522                                                   LLVMPassManagerRef PM) {
 523   PassManagerBuilder *Builder = unwrap(PMB);
 524   FunctionPassManager *FPM = unwrap<FunctionPassManager>(PM);
 525   Builder->populateFunctionPassManager(*FPM);
 526 }
 527
 528 void
 529 LLVMPassManagerBuilderPopulateModulePassManager(LLVMPassManagerBuilderRef PMB,
 530                                                 LLVMPassManagerRef PM) {
 531   PassManagerBuilder *Builder = unwrap(PMB);
 532   PassManagerBase *MPM = unwrap(PM);
 533   Builder->populateModulePassManager(*MPM);
 534 }
 535
 536 void LLVMPassManagerBuilderPopulateLTOPassManager(LLVMPassManagerBuilderRef PMB,
 537                                                   LLVMPassManagerRef PM,
 538                                                   LLVMBool Internalize,
 539                                                   LLVMBool RunInliner) {
 540   PassManagerBuilder *Builder = unwrap(PMB);
 541   PassManagerBase *LPM = unwrap(PM);
 542
 543   // A small backwards compatibility hack. populateLTOPassManager used to take
 544   // an RunInliner option.
 545   if (RunInliner && !Builder->Inliner)
 546     Builder->Inliner = createFunctionInliningPass();
 547
 548   Builder->populateLTOPassManager(*LPM);
 549 }