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      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/Analysis/Verifier.h"
     21 #include "llvm/PassManager.h"
     22 #include "llvm/Support/CommandLine.h"
     23 #include "llvm/Support/ManagedStatic.h"
     24 #include "llvm/Target/TargetLibraryInfo.h"
     25 #include "llvm/Transforms/IPO.h"
     26 #include "llvm/Transforms/Scalar.h"
     27 #include "llvm/Transforms/Vectorize.h"
     28 
     29 using namespace llvm;
     30 
     31 static cl::opt<bool>
     32 RunLoopVectorization("vectorize-loops",
     33                      cl::desc("Run the Loop vectorization passes"));
     34 
     35 static cl::opt<bool>
     36 LateVectorization("late-vectorize", cl::init(false), cl::Hidden,
     37                   cl::desc("Run the vectorization pasess late in the pass "
     38                            "pipeline (after the inliner)"));
     39 
     40 static cl::opt<bool>
     41 RunSLPVectorization("vectorize-slp",
     42                     cl::desc("Run the SLP vectorization passes"));
     43 
     44 static cl::opt<bool>
     45 RunBBVectorization("vectorize-slp-aggressive",
     46                     cl::desc("Run the BB vectorization passes"));
     47 
     48 static cl::opt<bool>
     49 UseGVNAfterVectorization("use-gvn-after-vectorization",
     50   cl::init(false), cl::Hidden,
     51   cl::desc("Run GVN instead of Early CSE after vectorization passes"));
     52 
     53 static cl::opt<bool> UseNewSROA("use-new-sroa",
     54   cl::init(true), cl::Hidden,
     55   cl::desc("Enable the new, experimental SROA pass"));
     56 
     57 PassManagerBuilder::PassManagerBuilder() {
     58     OptLevel = 2;
     59     SizeLevel = 0;
     60     LibraryInfo = 0;
     61     Inliner = 0;
     62     DisableUnitAtATime = false;
     63     DisableUnrollLoops = false;
     64     BBVectorize = RunBBVectorization;
     65     SLPVectorize = RunSLPVectorization;
     66     LoopVectorize = RunLoopVectorization;
     67     LateVectorize = LateVectorization;
     68 }
     69 
     70 PassManagerBuilder::~PassManagerBuilder() {
     71   delete LibraryInfo;
     72   delete Inliner;
     73 }
     74 
     75 /// Set of global extensions, automatically added as part of the standard set.
     76 static ManagedStatic<SmallVector<std::pair<PassManagerBuilder::ExtensionPointTy,
     77    PassManagerBuilder::ExtensionFn>, 8> > GlobalExtensions;
     78 
     79 void PassManagerBuilder::addGlobalExtension(
     80     PassManagerBuilder::ExtensionPointTy Ty,
     81     PassManagerBuilder::ExtensionFn Fn) {
     82   GlobalExtensions->push_back(std::make_pair(Ty, Fn));
     83 }
     84 
     85 void PassManagerBuilder::addExtension(ExtensionPointTy Ty, ExtensionFn Fn) {
     86   Extensions.push_back(std::make_pair(Ty, Fn));
     87 }
     88 
     89 void PassManagerBuilder::addExtensionsToPM(ExtensionPointTy ETy,
     90                                            PassManagerBase &PM) const {
     91   for (unsigned i = 0, e = GlobalExtensions->size(); i != e; ++i)
     92     if ((*GlobalExtensions)[i].first == ETy)
     93       (*GlobalExtensions)[i].second(*this, PM);
     94   for (unsigned i = 0, e = Extensions.size(); i != e; ++i)
     95     if (Extensions[i].first == ETy)
     96       Extensions[i].second(*this, PM);
     97 }
     98 
     99 void
    100 PassManagerBuilder::addInitialAliasAnalysisPasses(PassManagerBase &PM) const {
    101   // Add TypeBasedAliasAnalysis before BasicAliasAnalysis so that
    102   // BasicAliasAnalysis wins if they disagree. This is intended to help
    103   // support "obvious" type-punning idioms.
    104   PM.add(createTypeBasedAliasAnalysisPass());
    105   PM.add(createBasicAliasAnalysisPass());
    106 }
    107 
    108 void PassManagerBuilder::populateFunctionPassManager(FunctionPassManager &FPM) {
    109   addExtensionsToPM(EP_EarlyAsPossible, FPM);
    110 
    111   // Add LibraryInfo if we have some.
    112   if (LibraryInfo) FPM.add(new TargetLibraryInfo(*LibraryInfo));
    113 
    114   if (OptLevel == 0) return;
    115 
    116   addInitialAliasAnalysisPasses(FPM);
    117 
    118   FPM.add(createCFGSimplificationPass());
    119   if (UseNewSROA)
    120     FPM.add(createSROAPass());
    121   else
    122     FPM.add(createScalarReplAggregatesPass());
    123   FPM.add(createEarlyCSEPass());
    124   FPM.add(createLowerExpectIntrinsicPass());
    125 }
    126 
    127 void PassManagerBuilder::populateModulePassManager(PassManagerBase &MPM) {
    128   // If all optimizations are disabled, just run the always-inline pass.
    129   if (OptLevel == 0) {
    130     if (Inliner) {
    131       MPM.add(Inliner);
    132       Inliner = 0;
    133     }
    134 
    135     // FIXME: This is a HACK! The inliner pass above implicitly creates a CGSCC
    136     // pass manager, but we don't want to add extensions into that pass manager.
    137     // To prevent this we must insert a no-op module pass to reset the pass
    138     // manager to get the same behavior as EP_OptimizerLast in non-O0 builds.
    139     if (!GlobalExtensions->empty() || !Extensions.empty())
    140       MPM.add(createBarrierNoopPass());
    141 
    142     addExtensionsToPM(EP_EnabledOnOptLevel0, MPM);
    143     return;
    144   }
    145 
    146   // Add LibraryInfo if we have some.
    147   if (LibraryInfo) MPM.add(new TargetLibraryInfo(*LibraryInfo));
    148 
    149   addInitialAliasAnalysisPasses(MPM);
    150 
    151   if (!DisableUnitAtATime) {
    152     addExtensionsToPM(EP_ModuleOptimizerEarly, MPM);
    153 
    154     MPM.add(createGlobalOptimizerPass());     // Optimize out global vars
    155 
    156     MPM.add(createIPSCCPPass());              // IP SCCP
    157     MPM.add(createDeadArgEliminationPass());  // Dead argument elimination
    158 
    159     MPM.add(createInstructionCombiningPass());// Clean up after IPCP & DAE
    160     MPM.add(createCFGSimplificationPass());   // Clean up after IPCP & DAE
    161   }
    162 
    163   // Start of CallGraph SCC passes.
    164   if (!DisableUnitAtATime)
    165     MPM.add(createPruneEHPass());             // Remove dead EH info
    166   if (Inliner) {
    167     MPM.add(Inliner);
    168     Inliner = 0;
    169   }
    170   if (!DisableUnitAtATime)
    171     MPM.add(createFunctionAttrsPass());       // Set readonly/readnone attrs
    172   if (OptLevel > 2)
    173     MPM.add(createArgumentPromotionPass());   // Scalarize uninlined fn args
    174 
    175   // Start of function pass.
    176   // Break up aggregate allocas, using SSAUpdater.
    177   if (UseNewSROA)
    178     MPM.add(createSROAPass(/*RequiresDomTree*/ false));
    179   else
    180     MPM.add(createScalarReplAggregatesPass(-1, false));
    181   MPM.add(createEarlyCSEPass());              // Catch trivial redundancies
    182   MPM.add(createJumpThreadingPass());         // Thread jumps.
    183   MPM.add(createCorrelatedValuePropagationPass()); // Propagate conditionals
    184   MPM.add(createCFGSimplificationPass());     // Merge & remove BBs
    185   MPM.add(createInstructionCombiningPass());  // Combine silly seq's
    186 
    187   MPM.add(createTailCallEliminationPass());   // Eliminate tail calls
    188   MPM.add(createCFGSimplificationPass());     // Merge & remove BBs
    189   MPM.add(createReassociatePass());           // Reassociate expressions
    190   MPM.add(createLoopRotatePass());            // Rotate Loop
    191   MPM.add(createLICMPass());                  // Hoist loop invariants
    192   MPM.add(createLoopUnswitchPass(SizeLevel || OptLevel < 3));
    193   MPM.add(createInstructionCombiningPass());
    194   MPM.add(createIndVarSimplifyPass());        // Canonicalize indvars
    195   MPM.add(createLoopIdiomPass());             // Recognize idioms like memset.
    196   MPM.add(createLoopDeletionPass());          // Delete dead loops
    197 
    198   if (!LateVectorize && LoopVectorize && OptLevel > 1 && SizeLevel < 2)
    199       MPM.add(createLoopVectorizePass());
    200 
    201   if (!DisableUnrollLoops)
    202     MPM.add(createLoopUnrollPass());          // Unroll small loops
    203   addExtensionsToPM(EP_LoopOptimizerEnd, MPM);
    204 
    205   if (OptLevel > 1)
    206     MPM.add(createGVNPass());                 // Remove redundancies
    207   MPM.add(createMemCpyOptPass());             // Remove memcpy / form memset
    208   MPM.add(createSCCPPass());                  // Constant prop with SCCP
    209 
    210   // Run instcombine after redundancy elimination to exploit opportunities
    211   // opened up by them.
    212   MPM.add(createInstructionCombiningPass());
    213   MPM.add(createJumpThreadingPass());         // Thread jumps
    214   MPM.add(createCorrelatedValuePropagationPass());
    215   MPM.add(createDeadStoreEliminationPass());  // Delete dead stores
    216 
    217   addExtensionsToPM(EP_ScalarOptimizerLate, MPM);
    218 
    219   if (!LateVectorize) {
    220     if (SLPVectorize)
    221       MPM.add(createSLPVectorizerPass());   // Vectorize parallel scalar chains.
    222 
    223     if (BBVectorize) {
    224       MPM.add(createBBVectorizePass());
    225       MPM.add(createInstructionCombiningPass());
    226       if (OptLevel > 1 && UseGVNAfterVectorization)
    227         MPM.add(createGVNPass());           // Remove redundancies
    228       else
    229         MPM.add(createEarlyCSEPass());      // Catch trivial redundancies
    230 
    231       // BBVectorize may have significantly shortened a loop body; unroll again.
    232       if (!DisableUnrollLoops)
    233         MPM.add(createLoopUnrollPass());
    234     }
    235   }
    236 
    237   MPM.add(createAggressiveDCEPass());         // Delete dead instructions
    238   MPM.add(createCFGSimplificationPass()); // Merge & remove BBs
    239   MPM.add(createInstructionCombiningPass());  // Clean up after everything.
    240 
    241   // As an experimental mode, run any vectorization passes in a separate
    242   // pipeline from the CGSCC pass manager that runs iteratively with the
    243   // inliner.
    244   if (LateVectorize) {
    245     // FIXME: This is a HACK! The inliner pass above implicitly creates a CGSCC
    246     // pass manager that we are specifically trying to avoid. To prevent this
    247     // we must insert a no-op module pass to reset the pass manager.
    248     MPM.add(createBarrierNoopPass());
    249 
    250     // Add the various vectorization passes and relevant cleanup passes for
    251     // them since we are no longer in the middle of the main scalar pipeline.
    252     if (LoopVectorize && OptLevel > 1 && SizeLevel < 2) {
    253       MPM.add(createLoopVectorizePass());
    254 
    255       if (!DisableUnrollLoops)
    256         MPM.add(createLoopUnrollPass());    // Unroll small loops
    257 
    258       // FIXME: Is this necessary/useful? Should we also do SimplifyCFG?
    259       MPM.add(createInstructionCombiningPass());
    260     }
    261 
    262     if (SLPVectorize) {
    263       MPM.add(createSLPVectorizerPass());   // Vectorize parallel scalar chains.
    264 
    265       // FIXME: Is this necessary/useful? Should we also do SimplifyCFG?
    266       MPM.add(createInstructionCombiningPass());
    267     }
    268 
    269     if (BBVectorize) {
    270       MPM.add(createBBVectorizePass());
    271       MPM.add(createInstructionCombiningPass());
    272       if (OptLevel > 1 && UseGVNAfterVectorization)
    273         MPM.add(createGVNPass());           // Remove redundancies
    274       else
    275         MPM.add(createEarlyCSEPass());      // Catch trivial redundancies
    276 
    277       // BBVectorize may have significantly shortened a loop body; unroll again.
    278       if (!DisableUnrollLoops)
    279         MPM.add(createLoopUnrollPass());
    280     }
    281   }
    282 
    283   if (!DisableUnitAtATime) {
    284     // FIXME: We shouldn't bother with this anymore.
    285     MPM.add(createStripDeadPrototypesPass()); // Get rid of dead prototypes
    286 
    287     // GlobalOpt already deletes dead functions and globals, at -O2 try a
    288     // late pass of GlobalDCE.  It is capable of deleting dead cycles.
    289     if (OptLevel > 1) {
    290       MPM.add(createGlobalDCEPass());         // Remove dead fns and globals.
    291       MPM.add(createConstantMergePass());     // Merge dup global constants
    292     }
    293   }
    294   addExtensionsToPM(EP_OptimizerLast, MPM);
    295 }
    296 
    297 void PassManagerBuilder::populateLTOPassManager(PassManagerBase &PM,
    298                                                 bool Internalize,
    299                                                 bool RunInliner,
    300                                                 bool DisableGVNLoadPRE) {
    301   // Provide AliasAnalysis services for optimizations.
    302   addInitialAliasAnalysisPasses(PM);
    303 
    304   // Now that composite has been compiled, scan through the module, looking
    305   // for a main function.  If main is defined, mark all other functions
    306   // internal.
    307   if (Internalize) {
    308     std::vector<const char*> E;
    309     E.push_back("main");
    310     PM.add(createInternalizePass(E));
    311   }
    312 
    313   // Propagate constants at call sites into the functions they call.  This
    314   // opens opportunities for globalopt (and inlining) by substituting function
    315   // pointers passed as arguments to direct uses of functions.
    316   PM.add(createIPSCCPPass());
    317 
    318   // Now that we internalized some globals, see if we can hack on them!
    319   PM.add(createGlobalOptimizerPass());
    320 
    321   // Linking modules together can lead to duplicated global constants, only
    322   // keep one copy of each constant.
    323   PM.add(createConstantMergePass());
    324 
    325   // Remove unused arguments from functions.
    326   PM.add(createDeadArgEliminationPass());
    327 
    328   // Reduce the code after globalopt and ipsccp.  Both can open up significant
    329   // simplification opportunities, and both can propagate functions through
    330   // function pointers.  When this happens, we often have to resolve varargs
    331   // calls, etc, so let instcombine do this.
    332   PM.add(createInstructionCombiningPass());
    333 
    334   // Inline small functions
    335   if (RunInliner)
    336     PM.add(createFunctionInliningPass());
    337 
    338   PM.add(createPruneEHPass());   // Remove dead EH info.
    339 
    340   // Optimize globals again if we ran the inliner.
    341   if (RunInliner)
    342     PM.add(createGlobalOptimizerPass());
    343   PM.add(createGlobalDCEPass()); // Remove dead functions.
    344 
    345   // If we didn't decide to inline a function, check to see if we can
    346   // transform it to pass arguments by value instead of by reference.
    347   PM.add(createArgumentPromotionPass());
    348 
    349   // The IPO passes may leave cruft around.  Clean up after them.
    350   PM.add(createInstructionCombiningPass());
    351   PM.add(createJumpThreadingPass());
    352   // Break up allocas
    353   if (UseNewSROA)
    354     PM.add(createSROAPass());
    355   else
    356     PM.add(createScalarReplAggregatesPass());
    357 
    358   // Run a few AA driven optimizations here and now, to cleanup the code.
    359   PM.add(createFunctionAttrsPass()); // Add nocapture.
    360   PM.add(createGlobalsModRefPass()); // IP alias analysis.
    361 
    362   PM.add(createLICMPass());                 // Hoist loop invariants.
    363   PM.add(createGVNPass(DisableGVNLoadPRE)); // Remove redundancies.
    364   PM.add(createMemCpyOptPass());            // Remove dead memcpys.
    365   // Nuke dead stores.
    366   PM.add(createDeadStoreEliminationPass());
    367 
    368   // Cleanup and simplify the code after the scalar optimizations.
    369   PM.add(createInstructionCombiningPass());
    370 
    371   PM.add(createJumpThreadingPass());
    372 
    373   // Delete basic blocks, which optimization passes may have killed.
    374   PM.add(createCFGSimplificationPass());
    375 
    376   // Now that we have optimized the program, discard unreachable functions.
    377   PM.add(createGlobalDCEPass());
    378 }
    379 
    380 inline PassManagerBuilder *unwrap(LLVMPassManagerBuilderRef P) {
    381     return reinterpret_cast<PassManagerBuilder*>(P);
    382 }
    383 
    384 inline LLVMPassManagerBuilderRef wrap(PassManagerBuilder *P) {
    385   return reinterpret_cast<LLVMPassManagerBuilderRef>(P);
    386 }
    387 
    388 LLVMPassManagerBuilderRef LLVMPassManagerBuilderCreate() {
    389   PassManagerBuilder *PMB = new PassManagerBuilder();
    390   return wrap(PMB);
    391 }
    392 
    393 void LLVMPassManagerBuilderDispose(LLVMPassManagerBuilderRef PMB) {
    394   PassManagerBuilder *Builder = unwrap(PMB);
    395   delete Builder;
    396 }
    397 
    398 void
    399 LLVMPassManagerBuilderSetOptLevel(LLVMPassManagerBuilderRef PMB,
    400                                   unsigned OptLevel) {
    401   PassManagerBuilder *Builder = unwrap(PMB);
    402   Builder->OptLevel = OptLevel;
    403 }
    404 
    405 void
    406 LLVMPassManagerBuilderSetSizeLevel(LLVMPassManagerBuilderRef PMB,
    407                                    unsigned SizeLevel) {
    408   PassManagerBuilder *Builder = unwrap(PMB);
    409   Builder->SizeLevel = SizeLevel;
    410 }
    411 
    412 void
    413 LLVMPassManagerBuilderSetDisableUnitAtATime(LLVMPassManagerBuilderRef PMB,
    414                                             LLVMBool Value) {
    415   PassManagerBuilder *Builder = unwrap(PMB);
    416   Builder->DisableUnitAtATime = Value;
    417 }
    418 
    419 void
    420 LLVMPassManagerBuilderSetDisableUnrollLoops(LLVMPassManagerBuilderRef PMB,
    421                                             LLVMBool Value) {
    422   PassManagerBuilder *Builder = unwrap(PMB);
    423   Builder->DisableUnrollLoops = Value;
    424 }
    425 
    426 void
    427 LLVMPassManagerBuilderSetDisableSimplifyLibCalls(LLVMPassManagerBuilderRef PMB,
    428                                                  LLVMBool Value) {
    429   // NOTE: The simplify-libcalls pass has been removed.
    430 }
    431 
    432 void
    433 LLVMPassManagerBuilderUseInlinerWithThreshold(LLVMPassManagerBuilderRef PMB,
    434                                               unsigned Threshold) {
    435   PassManagerBuilder *Builder = unwrap(PMB);
    436   Builder->Inliner = createFunctionInliningPass(Threshold);
    437 }
    438 
    439 void
    440 LLVMPassManagerBuilderPopulateFunctionPassManager(LLVMPassManagerBuilderRef PMB,
    441                                                   LLVMPassManagerRef PM) {
    442   PassManagerBuilder *Builder = unwrap(PMB);
    443   FunctionPassManager *FPM = unwrap<FunctionPassManager>(PM);
    444   Builder->populateFunctionPassManager(*FPM);
    445 }
    446 
    447 void
    448 LLVMPassManagerBuilderPopulateModulePassManager(LLVMPassManagerBuilderRef PMB,
    449                                                 LLVMPassManagerRef PM) {
    450   PassManagerBuilder *Builder = unwrap(PMB);
    451   PassManagerBase *MPM = unwrap(PM);
    452   Builder->populateModulePassManager(*MPM);
    453 }
    454 
    455 void LLVMPassManagerBuilderPopulateLTOPassManager(LLVMPassManagerBuilderRef PMB,
    456                                                   LLVMPassManagerRef PM,
    457                                                   LLVMBool Internalize,
    458                                                   LLVMBool RunInliner) {
    459   PassManagerBuilder *Builder = unwrap(PMB);
    460   PassManagerBase *LPM = unwrap(PM);
    461   Builder->populateLTOPassManager(*LPM, Internalize != 0, RunInliner != 0);
    462 }
    463