1 //===- PassManagerBuilder.cpp - Build Standard Pass -----------------------===//
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 // This file defines the PassManagerBuilder class, which is used to set up a
10 // "standard" optimization sequence suitable for languages like C and C++.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
15 #include "llvm-c/Transforms/PassManagerBuilder.h"
16 #include "llvm/ADT/STLExtras.h"
17 #include "llvm/ADT/SmallVector.h"
18 #include "llvm/Analysis/BasicAliasAnalysis.h"
19 #include "llvm/Analysis/CFLAndersAliasAnalysis.h"
20 #include "llvm/Analysis/CFLSteensAliasAnalysis.h"
21 #include "llvm/Analysis/GlobalsModRef.h"
22 #include "llvm/Analysis/InlineCost.h"
23 #include "llvm/Analysis/Passes.h"
24 #include "llvm/Analysis/ScopedNoAliasAA.h"
25 #include "llvm/Analysis/TargetLibraryInfo.h"
26 #include "llvm/Analysis/TypeBasedAliasAnalysis.h"
27 #include "llvm/IR/DataLayout.h"
28 #include "llvm/IR/LegacyPassManager.h"
29 #include "llvm/IR/Verifier.h"
30 #include "llvm/Support/CommandLine.h"
31 #include "llvm/Support/ManagedStatic.h"
32 #include "llvm/Transforms/AggressiveInstCombine/AggressiveInstCombine.h"
33 #include "llvm/Transforms/IPO.h"
34 #include "llvm/Transforms/IPO/Attributor.h"
35 #include "llvm/Transforms/IPO/ForceFunctionAttrs.h"
36 #include "llvm/Transforms/IPO/FunctionAttrs.h"
37 #include "llvm/Transforms/IPO/InferFunctionAttrs.h"
38 #include "llvm/Transforms/InstCombine/InstCombine.h"
39 #include "llvm/Transforms/Instrumentation.h"
40 #include "llvm/Transforms/Scalar.h"
41 #include "llvm/Transforms/Scalar/GVN.h"
42 #include "llvm/Transforms/Scalar/InstSimplifyPass.h"
43 #include "llvm/Transforms/Scalar/LICM.h"
44 #include "llvm/Transforms/Scalar/LoopUnrollPass.h"
45 #include "llvm/Transforms/Scalar/SimpleLoopUnswitch.h"
46 #include "llvm/Transforms/Utils.h"
47 #include "llvm/Transforms/Vectorize.h"
48 #include "llvm/Transforms/Vectorize/LoopVectorize.h"
49 #include "llvm/Transforms/Vectorize/SLPVectorizer.h"
50 
51 using namespace llvm;
52 
53 static cl::opt<bool>
54     RunPartialInlining("enable-partial-inlining", cl::init(false), cl::Hidden,
55                        cl::ZeroOrMore, cl::desc("Run Partial inlinining pass"));
56 
57 static cl::opt<bool>
58 UseGVNAfterVectorization("use-gvn-after-vectorization",
59   cl::init(false), cl::Hidden,
60   cl::desc("Run GVN instead of Early CSE after vectorization passes"));
61 
62 static cl::opt<bool> ExtraVectorizerPasses(
63     "extra-vectorizer-passes", cl::init(false), cl::Hidden,
64     cl::desc("Run cleanup optimization passes after vectorization."));
65 
66 static cl::opt<bool>
67 RunLoopRerolling("reroll-loops", cl::Hidden,
68                  cl::desc("Run the loop rerolling pass"));
69 
70 static cl::opt<bool> RunNewGVN("enable-newgvn", cl::init(false), cl::Hidden,
71                                cl::desc("Run the NewGVN pass"));
72 
73 // Experimental option to use CFL-AA
74 enum class CFLAAType { None, Steensgaard, Andersen, Both };
75 static cl::opt<CFLAAType>
76     UseCFLAA("use-cfl-aa", cl::init(CFLAAType::None), cl::Hidden,
77              cl::desc("Enable the new, experimental CFL alias analysis"),
78              cl::values(clEnumValN(CFLAAType::None, "none", "Disable CFL-AA"),
79                         clEnumValN(CFLAAType::Steensgaard, "steens",
80                                    "Enable unification-based CFL-AA"),
81                         clEnumValN(CFLAAType::Andersen, "anders",
82                                    "Enable inclusion-based CFL-AA"),
83                         clEnumValN(CFLAAType::Both, "both",
84                                    "Enable both variants of CFL-AA")));
85 
86 static cl::opt<bool> EnableLoopInterchange(
87     "enable-loopinterchange", cl::init(false), cl::Hidden,
88     cl::desc("Enable the new, experimental LoopInterchange Pass"));
89 
90 static cl::opt<bool> EnableUnrollAndJam("enable-unroll-and-jam",
91                                         cl::init(false), cl::Hidden,
92                                         cl::desc("Enable Unroll And Jam Pass"));
93 
94 static cl::opt<bool>
95     EnablePrepareForThinLTO("prepare-for-thinlto", cl::init(false), cl::Hidden,
96                             cl::desc("Enable preparation for ThinLTO."));
97 
98 static cl::opt<bool>
99     EnablePerformThinLTO("perform-thinlto", cl::init(false), cl::Hidden,
100                          cl::desc("Enable performing ThinLTO."));
101 
102 cl::opt<bool> EnableHotColdSplit("hot-cold-split", cl::init(false), cl::Hidden,
103     cl::desc("Enable hot-cold splitting pass"));
104 
105 static cl::opt<bool> UseLoopVersioningLICM(
106     "enable-loop-versioning-licm", cl::init(false), cl::Hidden,
107     cl::desc("Enable the experimental Loop Versioning LICM pass"));
108 
109 static cl::opt<bool>
110     DisablePreInliner("disable-preinline", cl::init(false), cl::Hidden,
111                       cl::desc("Disable pre-instrumentation inliner"));
112 
113 static cl::opt<int> PreInlineThreshold(
114     "preinline-threshold", cl::Hidden, cl::init(75), cl::ZeroOrMore,
115     cl::desc("Control the amount of inlining in pre-instrumentation inliner "
116              "(default = 75)"));
117 
118 static cl::opt<bool> EnableGVNHoist(
119     "enable-gvn-hoist", cl::init(false), cl::Hidden,
120     cl::desc("Enable the GVN hoisting pass (default = off)"));
121 
122 static cl::opt<bool>
123     DisableLibCallsShrinkWrap("disable-libcalls-shrinkwrap", cl::init(false),
124                               cl::Hidden,
125                               cl::desc("Disable shrink-wrap library calls"));
126 
127 static cl::opt<bool> EnableSimpleLoopUnswitch(
128     "enable-simple-loop-unswitch", cl::init(false), cl::Hidden,
129     cl::desc("Enable the simple loop unswitch pass. Also enables independent "
130              "cleanup passes integrated into the loop pass manager pipeline."));
131 
132 static cl::opt<bool> EnableGVNSink(
133     "enable-gvn-sink", cl::init(false), cl::Hidden,
134     cl::desc("Enable the GVN sinking pass (default = off)"));
135 
136 // This option is used in simplifying testing SampleFDO optimizations for
137 // profile loading.
138 static cl::opt<bool>
139     EnableCHR("enable-chr", cl::init(true), cl::Hidden,
140               cl::desc("Enable control height reduction optimization (CHR)"));
141 
142 cl::opt<bool> FlattenedProfileUsed(
143     "flattened-profile-used", cl::init(false), cl::Hidden,
144     cl::desc("Indicate the sample profile being used is flattened, i.e., "
145              "no inline hierachy exists in the profile. "));
146 
147 cl::opt<bool> EnableOrderFileInstrumentation(
148     "enable-order-file-instrumentation", cl::init(false), cl::Hidden,
149     cl::desc("Enable order file instrumentation (default = off)"));
150 
151 static cl::opt<bool>
152     EnableMatrix("enable-matrix", cl::init(false), cl::Hidden,
153                  cl::desc("Enable lowering of the matrix intrinsics"));
154 
155 PassManagerBuilder::PassManagerBuilder() {
156     OptLevel = 2;
157     SizeLevel = 0;
158     LibraryInfo = nullptr;
159     Inliner = nullptr;
160     DisableUnrollLoops = false;
161     SLPVectorize = RunSLPVectorization;
162     LoopVectorize = EnableLoopVectorization;
163     LoopsInterleaved = EnableLoopInterleaving;
164     RerollLoops = RunLoopRerolling;
165     NewGVN = RunNewGVN;
166     LicmMssaOptCap = SetLicmMssaOptCap;
167     LicmMssaNoAccForPromotionCap = SetLicmMssaNoAccForPromotionCap;
168     DisableGVNLoadPRE = false;
169     ForgetAllSCEVInLoopUnroll = ForgetSCEVInLoopUnroll;
170     VerifyInput = false;
171     VerifyOutput = false;
172     MergeFunctions = false;
173     PrepareForLTO = false;
174     EnablePGOInstrGen = false;
175     EnablePGOCSInstrGen = false;
176     EnablePGOCSInstrUse = false;
177     PGOInstrGen = "";
178     PGOInstrUse = "";
179     PGOSampleUse = "";
180     PrepareForThinLTO = EnablePrepareForThinLTO;
181     PerformThinLTO = EnablePerformThinLTO;
182     DivergentTarget = false;
183 }
184 
185 PassManagerBuilder::~PassManagerBuilder() {
186   delete LibraryInfo;
187   delete Inliner;
188 }
189 
190 /// Set of global extensions, automatically added as part of the standard set.
191 static ManagedStatic<
192     SmallVector<std::tuple<PassManagerBuilder::ExtensionPointTy,
193                            PassManagerBuilder::ExtensionFn,
194                            PassManagerBuilder::GlobalExtensionID>,
195                 8>>
196     GlobalExtensions;
197 static PassManagerBuilder::GlobalExtensionID GlobalExtensionsCounter;
198 
199 /// Check if GlobalExtensions is constructed and not empty.
200 /// Since GlobalExtensions is a managed static, calling 'empty()' will trigger
201 /// the construction of the object.
202 static bool GlobalExtensionsNotEmpty() {
203   return GlobalExtensions.isConstructed() && !GlobalExtensions->empty();
204 }
205 
206 PassManagerBuilder::GlobalExtensionID
207 PassManagerBuilder::addGlobalExtension(PassManagerBuilder::ExtensionPointTy Ty,
208                                        PassManagerBuilder::ExtensionFn Fn) {
209   auto ExtensionID = GlobalExtensionsCounter++;
210   GlobalExtensions->push_back(std::make_tuple(Ty, std::move(Fn), ExtensionID));
211   return ExtensionID;
212 }
213 
214 void PassManagerBuilder::removeGlobalExtension(
215     PassManagerBuilder::GlobalExtensionID ExtensionID) {
216   // RegisterStandardPasses may try to call this function after GlobalExtensions
217   // has already been destroyed; doing so should not generate an error.
218   if (!GlobalExtensions.isConstructed())
219     return;
220 
221   auto GlobalExtension =
222       llvm::find_if(*GlobalExtensions, [ExtensionID](const auto &elem) {
223         return std::get<2>(elem) == ExtensionID;
224       });
225   assert(GlobalExtension != GlobalExtensions->end() &&
226          "The extension ID to be removed should always be valid.");
227 
228   GlobalExtensions->erase(GlobalExtension);
229 }
230 
231 void PassManagerBuilder::addExtension(ExtensionPointTy Ty, ExtensionFn Fn) {
232   Extensions.push_back(std::make_pair(Ty, std::move(Fn)));
233 }
234 
235 void PassManagerBuilder::addExtensionsToPM(ExtensionPointTy ETy,
236                                            legacy::PassManagerBase &PM) const {
237   if (GlobalExtensionsNotEmpty()) {
238     for (auto &Ext : *GlobalExtensions) {
239       if (std::get<0>(Ext) == ETy)
240         std::get<1>(Ext)(*this, PM);
241     }
242   }
243   for (unsigned i = 0, e = Extensions.size(); i != e; ++i)
244     if (Extensions[i].first == ETy)
245       Extensions[i].second(*this, PM);
246 }
247 
248 void PassManagerBuilder::addInitialAliasAnalysisPasses(
249     legacy::PassManagerBase &PM) const {
250   switch (UseCFLAA) {
251   case CFLAAType::Steensgaard:
252     PM.add(createCFLSteensAAWrapperPass());
253     break;
254   case CFLAAType::Andersen:
255     PM.add(createCFLAndersAAWrapperPass());
256     break;
257   case CFLAAType::Both:
258     PM.add(createCFLSteensAAWrapperPass());
259     PM.add(createCFLAndersAAWrapperPass());
260     break;
261   default:
262     break;
263   }
264 
265   // Add TypeBasedAliasAnalysis before BasicAliasAnalysis so that
266   // BasicAliasAnalysis wins if they disagree. This is intended to help
267   // support "obvious" type-punning idioms.
268   PM.add(createTypeBasedAAWrapperPass());
269   PM.add(createScopedNoAliasAAWrapperPass());
270 }
271 
272 void PassManagerBuilder::addInstructionCombiningPass(
273     legacy::PassManagerBase &PM) const {
274   bool ExpensiveCombines = OptLevel > 2;
275   PM.add(createInstructionCombiningPass(ExpensiveCombines));
276 }
277 
278 void PassManagerBuilder::populateFunctionPassManager(
279     legacy::FunctionPassManager &FPM) {
280   addExtensionsToPM(EP_EarlyAsPossible, FPM);
281   FPM.add(createEntryExitInstrumenterPass());
282 
283   // Add LibraryInfo if we have some.
284   if (LibraryInfo)
285     FPM.add(new TargetLibraryInfoWrapperPass(*LibraryInfo));
286 
287   if (OptLevel == 0) return;
288 
289   addInitialAliasAnalysisPasses(FPM);
290 
291   FPM.add(createCFGSimplificationPass());
292   FPM.add(createSROAPass());
293   FPM.add(createEarlyCSEPass());
294   FPM.add(createLowerExpectIntrinsicPass());
295 }
296 
297 // Do PGO instrumentation generation or use pass as the option specified.
298 void PassManagerBuilder::addPGOInstrPasses(legacy::PassManagerBase &MPM,
299                                            bool IsCS = false) {
300   if (IsCS) {
301     if (!EnablePGOCSInstrGen && !EnablePGOCSInstrUse)
302       return;
303   } else if (!EnablePGOInstrGen && PGOInstrUse.empty() && PGOSampleUse.empty())
304     return;
305 
306   // Perform the preinline and cleanup passes for O1 and above.
307   // And avoid doing them if optimizing for size.
308   // We will not do this inline for context sensitive PGO (when IsCS is true).
309   if (OptLevel > 0 && SizeLevel == 0 && !DisablePreInliner &&
310       PGOSampleUse.empty() && !IsCS) {
311     // Create preinline pass. We construct an InlineParams object and specify
312     // the threshold here to avoid the command line options of the regular
313     // inliner to influence pre-inlining. The only fields of InlineParams we
314     // care about are DefaultThreshold and HintThreshold.
315     InlineParams IP;
316     IP.DefaultThreshold = PreInlineThreshold;
317     // FIXME: The hint threshold has the same value used by the regular inliner.
318     // This should probably be lowered after performance testing.
319     IP.HintThreshold = 325;
320 
321     MPM.add(createFunctionInliningPass(IP));
322     MPM.add(createSROAPass());
323     MPM.add(createEarlyCSEPass());             // Catch trivial redundancies
324     MPM.add(createCFGSimplificationPass());    // Merge & remove BBs
325     MPM.add(createInstructionCombiningPass()); // Combine silly seq's
326     addExtensionsToPM(EP_Peephole, MPM);
327   }
328   if ((EnablePGOInstrGen && !IsCS) || (EnablePGOCSInstrGen && IsCS)) {
329     MPM.add(createPGOInstrumentationGenLegacyPass(IsCS));
330     // Add the profile lowering pass.
331     InstrProfOptions Options;
332     if (!PGOInstrGen.empty())
333       Options.InstrProfileOutput = PGOInstrGen;
334     Options.DoCounterPromotion = true;
335     Options.UseBFIInPromotion = IsCS;
336     MPM.add(createLoopRotatePass());
337     MPM.add(createInstrProfilingLegacyPass(Options, IsCS));
338   }
339   if (!PGOInstrUse.empty())
340     MPM.add(createPGOInstrumentationUseLegacyPass(PGOInstrUse, IsCS));
341   // Indirect call promotion that promotes intra-module targets only.
342   // For ThinLTO this is done earlier due to interactions with globalopt
343   // for imported functions. We don't run this at -O0.
344   if (OptLevel > 0 && !IsCS)
345     MPM.add(
346         createPGOIndirectCallPromotionLegacyPass(false, !PGOSampleUse.empty()));
347 }
348 void PassManagerBuilder::addFunctionSimplificationPasses(
349     legacy::PassManagerBase &MPM) {
350   // Start of function pass.
351   // Break up aggregate allocas, using SSAUpdater.
352   assert(OptLevel >= 1 && "Calling function optimizer with no optimization level!");
353   MPM.add(createSROAPass());
354   MPM.add(createEarlyCSEPass(true /* Enable mem-ssa. */)); // Catch trivial redundancies
355 
356   if (OptLevel > 1) {
357     if (EnableGVNHoist)
358       MPM.add(createGVNHoistPass());
359     if (EnableGVNSink) {
360       MPM.add(createGVNSinkPass());
361       MPM.add(createCFGSimplificationPass());
362     }
363   }
364 
365   if (OptLevel > 1) {
366     // Speculative execution if the target has divergent branches; otherwise nop.
367     MPM.add(createSpeculativeExecutionIfHasBranchDivergencePass());
368 
369     MPM.add(createJumpThreadingPass());         // Thread jumps.
370     MPM.add(createCorrelatedValuePropagationPass()); // Propagate conditionals
371   }
372   MPM.add(createCFGSimplificationPass());     // Merge & remove BBs
373   // Combine silly seq's
374   if (OptLevel > 2)
375     MPM.add(createAggressiveInstCombinerPass());
376   addInstructionCombiningPass(MPM);
377   if (SizeLevel == 0 && !DisableLibCallsShrinkWrap)
378     MPM.add(createLibCallsShrinkWrapPass());
379   addExtensionsToPM(EP_Peephole, MPM);
380 
381   // Optimize memory intrinsic calls based on the profiled size information.
382   if (SizeLevel == 0)
383     MPM.add(createPGOMemOPSizeOptLegacyPass());
384 
385   // TODO: Investigate the cost/benefit of tail call elimination on debugging.
386   if (OptLevel > 1)
387     MPM.add(createTailCallEliminationPass()); // Eliminate tail calls
388   MPM.add(createCFGSimplificationPass());      // Merge & remove BBs
389   MPM.add(createReassociatePass());           // Reassociate expressions
390 
391   // Begin the loop pass pipeline.
392   if (EnableSimpleLoopUnswitch) {
393     // The simple loop unswitch pass relies on separate cleanup passes. Schedule
394     // them first so when we re-process a loop they run before other loop
395     // passes.
396     MPM.add(createLoopInstSimplifyPass());
397     MPM.add(createLoopSimplifyCFGPass());
398   }
399   // Rotate Loop - disable header duplication at -Oz
400   MPM.add(createLoopRotatePass(SizeLevel == 2 ? 0 : -1));
401   // TODO: Investigate promotion cap for O1.
402   MPM.add(createLICMPass(LicmMssaOptCap, LicmMssaNoAccForPromotionCap));
403   if (EnableSimpleLoopUnswitch)
404     MPM.add(createSimpleLoopUnswitchLegacyPass());
405   else
406     MPM.add(createLoopUnswitchPass(SizeLevel || OptLevel < 3, DivergentTarget));
407   // FIXME: We break the loop pass pipeline here in order to do full
408   // simplify-cfg. Eventually loop-simplifycfg should be enhanced to replace the
409   // need for this.
410   MPM.add(createCFGSimplificationPass());
411   addInstructionCombiningPass(MPM);
412   // We resume loop passes creating a second loop pipeline here.
413   MPM.add(createIndVarSimplifyPass());        // Canonicalize indvars
414   MPM.add(createLoopIdiomPass());             // Recognize idioms like memset.
415   addExtensionsToPM(EP_LateLoopOptimizations, MPM);
416   MPM.add(createLoopDeletionPass());          // Delete dead loops
417 
418   if (EnableLoopInterchange)
419     MPM.add(createLoopInterchangePass()); // Interchange loops
420 
421   // Unroll small loops
422   MPM.add(createSimpleLoopUnrollPass(OptLevel, DisableUnrollLoops,
423                                      ForgetAllSCEVInLoopUnroll));
424   addExtensionsToPM(EP_LoopOptimizerEnd, MPM);
425   // This ends the loop pass pipelines.
426 
427   if (OptLevel > 1) {
428     MPM.add(createMergedLoadStoreMotionPass()); // Merge ld/st in diamonds
429     MPM.add(NewGVN ? createNewGVNPass()
430                    : createGVNPass(DisableGVNLoadPRE)); // Remove redundancies
431   }
432   MPM.add(createMemCpyOptPass());             // Remove memcpy / form memset
433   MPM.add(createSCCPPass());                  // Constant prop with SCCP
434 
435   // Delete dead bit computations (instcombine runs after to fold away the dead
436   // computations, and then ADCE will run later to exploit any new DCE
437   // opportunities that creates).
438   MPM.add(createBitTrackingDCEPass());        // Delete dead bit computations
439 
440   // Run instcombine after redundancy elimination to exploit opportunities
441   // opened up by them.
442   addInstructionCombiningPass(MPM);
443   addExtensionsToPM(EP_Peephole, MPM);
444   if (OptLevel > 1) {
445     MPM.add(createJumpThreadingPass());         // Thread jumps
446     MPM.add(createCorrelatedValuePropagationPass());
447     MPM.add(createDeadStoreEliminationPass());  // Delete dead stores
448     MPM.add(createLICMPass(LicmMssaOptCap, LicmMssaNoAccForPromotionCap));
449   }
450 
451   addExtensionsToPM(EP_ScalarOptimizerLate, MPM);
452 
453   if (RerollLoops)
454     MPM.add(createLoopRerollPass());
455 
456   // TODO: Investigate if this is too expensive at O1.
457   MPM.add(createAggressiveDCEPass());         // Delete dead instructions
458   MPM.add(createCFGSimplificationPass()); // Merge & remove BBs
459   // Clean up after everything.
460   addInstructionCombiningPass(MPM);
461   addExtensionsToPM(EP_Peephole, MPM);
462 
463   if (EnableCHR && OptLevel >= 3 &&
464       (!PGOInstrUse.empty() || !PGOSampleUse.empty() || EnablePGOCSInstrGen))
465     MPM.add(createControlHeightReductionLegacyPass());
466 }
467 
468 void PassManagerBuilder::populateModulePassManager(
469     legacy::PassManagerBase &MPM) {
470   // Whether this is a default or *LTO pre-link pipeline. The FullLTO post-link
471   // is handled separately, so just check this is not the ThinLTO post-link.
472   bool DefaultOrPreLinkPipeline = !PerformThinLTO;
473 
474   if (!PGOSampleUse.empty()) {
475     MPM.add(createPruneEHPass());
476     // In ThinLTO mode, when flattened profile is used, all the available
477     // profile information will be annotated in PreLink phase so there is
478     // no need to load the profile again in PostLink.
479     if (!(FlattenedProfileUsed && PerformThinLTO))
480       MPM.add(createSampleProfileLoaderPass(PGOSampleUse));
481   }
482 
483   // Allow forcing function attributes as a debugging and tuning aid.
484   MPM.add(createForceFunctionAttrsLegacyPass());
485 
486   // If all optimizations are disabled, just run the always-inline pass and,
487   // if enabled, the function merging pass.
488   if (OptLevel == 0) {
489     addPGOInstrPasses(MPM);
490     if (Inliner) {
491       MPM.add(Inliner);
492       Inliner = nullptr;
493     }
494 
495     // FIXME: The BarrierNoopPass is a HACK! The inliner pass above implicitly
496     // creates a CGSCC pass manager, but we don't want to add extensions into
497     // that pass manager. To prevent this we insert a no-op module pass to reset
498     // the pass manager to get the same behavior as EP_OptimizerLast in non-O0
499     // builds. The function merging pass is
500     if (MergeFunctions)
501       MPM.add(createMergeFunctionsPass());
502     else if (GlobalExtensionsNotEmpty() || !Extensions.empty())
503       MPM.add(createBarrierNoopPass());
504 
505     if (PerformThinLTO) {
506       MPM.add(createLowerTypeTestsPass(nullptr, nullptr, true));
507       // Drop available_externally and unreferenced globals. This is necessary
508       // with ThinLTO in order to avoid leaving undefined references to dead
509       // globals in the object file.
510       MPM.add(createEliminateAvailableExternallyPass());
511       MPM.add(createGlobalDCEPass());
512     }
513 
514     addExtensionsToPM(EP_EnabledOnOptLevel0, MPM);
515 
516     if (PrepareForLTO || PrepareForThinLTO) {
517       MPM.add(createCanonicalizeAliasesPass());
518       // Rename anon globals to be able to export them in the summary.
519       // This has to be done after we add the extensions to the pass manager
520       // as there could be passes (e.g. Adddress sanitizer) which introduce
521       // new unnamed globals.
522       MPM.add(createNameAnonGlobalPass());
523     }
524     return;
525   }
526 
527   // Add LibraryInfo if we have some.
528   if (LibraryInfo)
529     MPM.add(new TargetLibraryInfoWrapperPass(*LibraryInfo));
530 
531   addInitialAliasAnalysisPasses(MPM);
532 
533   // For ThinLTO there are two passes of indirect call promotion. The
534   // first is during the compile phase when PerformThinLTO=false and
535   // intra-module indirect call targets are promoted. The second is during
536   // the ThinLTO backend when PerformThinLTO=true, when we promote imported
537   // inter-module indirect calls. For that we perform indirect call promotion
538   // earlier in the pass pipeline, here before globalopt. Otherwise imported
539   // available_externally functions look unreferenced and are removed.
540   if (PerformThinLTO) {
541     MPM.add(createPGOIndirectCallPromotionLegacyPass(/*InLTO = */ true,
542                                                      !PGOSampleUse.empty()));
543     MPM.add(createLowerTypeTestsPass(nullptr, nullptr, true));
544   }
545 
546   // For SamplePGO in ThinLTO compile phase, we do not want to unroll loops
547   // as it will change the CFG too much to make the 2nd profile annotation
548   // in backend more difficult.
549   bool PrepareForThinLTOUsingPGOSampleProfile =
550       PrepareForThinLTO && !PGOSampleUse.empty();
551   if (PrepareForThinLTOUsingPGOSampleProfile)
552     DisableUnrollLoops = true;
553 
554   // Infer attributes about declarations if possible.
555   MPM.add(createInferFunctionAttrsLegacyPass());
556 
557   addExtensionsToPM(EP_ModuleOptimizerEarly, MPM);
558 
559   if (OptLevel > 2)
560     MPM.add(createCallSiteSplittingPass());
561 
562   MPM.add(createIPSCCPPass());          // IP SCCP
563   MPM.add(createCalledValuePropagationPass());
564 
565   // Infer attributes on declarations, call sites, arguments, etc.
566   MPM.add(createAttributorLegacyPass());
567 
568   MPM.add(createGlobalOptimizerPass()); // Optimize out global vars
569   // Promote any localized global vars.
570   MPM.add(createPromoteMemoryToRegisterPass());
571 
572   MPM.add(createDeadArgEliminationPass()); // Dead argument elimination
573 
574   addInstructionCombiningPass(MPM); // Clean up after IPCP & DAE
575   addExtensionsToPM(EP_Peephole, MPM);
576   MPM.add(createCFGSimplificationPass()); // Clean up after IPCP & DAE
577 
578   // For SamplePGO in ThinLTO compile phase, we do not want to do indirect
579   // call promotion as it will change the CFG too much to make the 2nd
580   // profile annotation in backend more difficult.
581   // PGO instrumentation is added during the compile phase for ThinLTO, do
582   // not run it a second time
583   if (DefaultOrPreLinkPipeline && !PrepareForThinLTOUsingPGOSampleProfile)
584     addPGOInstrPasses(MPM);
585 
586   // Create profile COMDAT variables. Lld linker wants to see all variables
587   // before the LTO/ThinLTO link since it needs to resolve symbols/comdats.
588   if (!PerformThinLTO && EnablePGOCSInstrGen)
589     MPM.add(createPGOInstrumentationGenCreateVarLegacyPass(PGOInstrGen));
590 
591   // We add a module alias analysis pass here. In part due to bugs in the
592   // analysis infrastructure this "works" in that the analysis stays alive
593   // for the entire SCC pass run below.
594   MPM.add(createGlobalsAAWrapperPass());
595 
596   // Start of CallGraph SCC passes.
597   MPM.add(createPruneEHPass()); // Remove dead EH info
598   bool RunInliner = false;
599   if (Inliner) {
600     MPM.add(Inliner);
601     Inliner = nullptr;
602     RunInliner = true;
603   }
604 
605   MPM.add(createPostOrderFunctionAttrsLegacyPass());
606   if (OptLevel > 2)
607     MPM.add(createArgumentPromotionPass()); // Scalarize uninlined fn args
608 
609   addExtensionsToPM(EP_CGSCCOptimizerLate, MPM);
610   addFunctionSimplificationPasses(MPM);
611 
612   // FIXME: This is a HACK! The inliner pass above implicitly creates a CGSCC
613   // pass manager that we are specifically trying to avoid. To prevent this
614   // we must insert a no-op module pass to reset the pass manager.
615   MPM.add(createBarrierNoopPass());
616 
617   if (RunPartialInlining)
618     MPM.add(createPartialInliningPass());
619 
620   if (OptLevel > 1 && !PrepareForLTO && !PrepareForThinLTO)
621     // Remove avail extern fns and globals definitions if we aren't
622     // compiling an object file for later LTO. For LTO we want to preserve
623     // these so they are eligible for inlining at link-time. Note if they
624     // are unreferenced they will be removed by GlobalDCE later, so
625     // this only impacts referenced available externally globals.
626     // Eventually they will be suppressed during codegen, but eliminating
627     // here enables more opportunity for GlobalDCE as it may make
628     // globals referenced by available external functions dead
629     // and saves running remaining passes on the eliminated functions.
630     MPM.add(createEliminateAvailableExternallyPass());
631 
632   // CSFDO instrumentation and use pass. Don't invoke this for Prepare pass
633   // for LTO and ThinLTO -- The actual pass will be called after all inlines
634   // are performed.
635   // Need to do this after COMDAT variables have been eliminated,
636   // (i.e. after EliminateAvailableExternallyPass).
637   if (!(PrepareForLTO || PrepareForThinLTO))
638     addPGOInstrPasses(MPM, /* IsCS */ true);
639 
640   if (EnableOrderFileInstrumentation)
641     MPM.add(createInstrOrderFilePass());
642 
643   MPM.add(createReversePostOrderFunctionAttrsPass());
644 
645   // The inliner performs some kind of dead code elimination as it goes,
646   // but there are cases that are not really caught by it. We might
647   // at some point consider teaching the inliner about them, but it
648   // is OK for now to run GlobalOpt + GlobalDCE in tandem as their
649   // benefits generally outweight the cost, making the whole pipeline
650   // faster.
651   if (RunInliner) {
652     MPM.add(createGlobalOptimizerPass());
653     MPM.add(createGlobalDCEPass());
654   }
655 
656   // If we are planning to perform ThinLTO later, let's not bloat the code with
657   // unrolling/vectorization/... now. We'll first run the inliner + CGSCC passes
658   // during ThinLTO and perform the rest of the optimizations afterward.
659   if (PrepareForThinLTO) {
660     // Ensure we perform any last passes, but do so before renaming anonymous
661     // globals in case the passes add any.
662     addExtensionsToPM(EP_OptimizerLast, MPM);
663     MPM.add(createCanonicalizeAliasesPass());
664     // Rename anon globals to be able to export them in the summary.
665     MPM.add(createNameAnonGlobalPass());
666     return;
667   }
668 
669   if (PerformThinLTO)
670     // Optimize globals now when performing ThinLTO, this enables more
671     // optimizations later.
672     MPM.add(createGlobalOptimizerPass());
673 
674   // Scheduling LoopVersioningLICM when inlining is over, because after that
675   // we may see more accurate aliasing. Reason to run this late is that too
676   // early versioning may prevent further inlining due to increase of code
677   // size. By placing it just after inlining other optimizations which runs
678   // later might get benefit of no-alias assumption in clone loop.
679   if (UseLoopVersioningLICM) {
680     MPM.add(createLoopVersioningLICMPass());    // Do LoopVersioningLICM
681     MPM.add(createLICMPass(LicmMssaOptCap, LicmMssaNoAccForPromotionCap));
682   }
683 
684   // We add a fresh GlobalsModRef run at this point. This is particularly
685   // useful as the above will have inlined, DCE'ed, and function-attr
686   // propagated everything. We should at this point have a reasonably minimal
687   // and richly annotated call graph. By computing aliasing and mod/ref
688   // information for all local globals here, the late loop passes and notably
689   // the vectorizer will be able to use them to help recognize vectorizable
690   // memory operations.
691   //
692   // Note that this relies on a bug in the pass manager which preserves
693   // a module analysis into a function pass pipeline (and throughout it) so
694   // long as the first function pass doesn't invalidate the module analysis.
695   // Thus both Float2Int and LoopRotate have to preserve AliasAnalysis for
696   // this to work. Fortunately, it is trivial to preserve AliasAnalysis
697   // (doing nothing preserves it as it is required to be conservatively
698   // correct in the face of IR changes).
699   MPM.add(createGlobalsAAWrapperPass());
700 
701   MPM.add(createFloat2IntPass());
702   MPM.add(createLowerConstantIntrinsicsPass());
703 
704   if (EnableMatrix) {
705     MPM.add(createLowerMatrixIntrinsicsPass());
706     // CSE the pointer arithmetic of the column vectors.  This allows alias
707     // analysis to establish no-aliasing between loads and stores of different
708     // columns of the same matrix.
709     MPM.add(createEarlyCSEPass(false));
710   }
711 
712   addExtensionsToPM(EP_VectorizerStart, MPM);
713 
714   // Re-rotate loops in all our loop nests. These may have fallout out of
715   // rotated form due to GVN or other transformations, and the vectorizer relies
716   // on the rotated form. Disable header duplication at -Oz.
717   MPM.add(createLoopRotatePass(SizeLevel == 2 ? 0 : -1));
718 
719   // Distribute loops to allow partial vectorization.  I.e. isolate dependences
720   // into separate loop that would otherwise inhibit vectorization.  This is
721   // currently only performed for loops marked with the metadata
722   // llvm.loop.distribute=true or when -enable-loop-distribute is specified.
723   MPM.add(createLoopDistributePass());
724 
725   MPM.add(createLoopVectorizePass(!LoopsInterleaved, !LoopVectorize));
726 
727   // Eliminate loads by forwarding stores from the previous iteration to loads
728   // of the current iteration.
729   MPM.add(createLoopLoadEliminationPass());
730 
731   // FIXME: Because of #pragma vectorize enable, the passes below are always
732   // inserted in the pipeline, even when the vectorizer doesn't run (ex. when
733   // on -O1 and no #pragma is found). Would be good to have these two passes
734   // as function calls, so that we can only pass them when the vectorizer
735   // changed the code.
736   addInstructionCombiningPass(MPM);
737   if (OptLevel > 1 && ExtraVectorizerPasses) {
738     // At higher optimization levels, try to clean up any runtime overlap and
739     // alignment checks inserted by the vectorizer. We want to track correllated
740     // runtime checks for two inner loops in the same outer loop, fold any
741     // common computations, hoist loop-invariant aspects out of any outer loop,
742     // and unswitch the runtime checks if possible. Once hoisted, we may have
743     // dead (or speculatable) control flows or more combining opportunities.
744     MPM.add(createEarlyCSEPass());
745     MPM.add(createCorrelatedValuePropagationPass());
746     addInstructionCombiningPass(MPM);
747     MPM.add(createLICMPass(LicmMssaOptCap, LicmMssaNoAccForPromotionCap));
748     MPM.add(createLoopUnswitchPass(SizeLevel || OptLevel < 3, DivergentTarget));
749     MPM.add(createCFGSimplificationPass());
750     addInstructionCombiningPass(MPM);
751   }
752 
753   // Cleanup after loop vectorization, etc. Simplification passes like CVP and
754   // GVN, loop transforms, and others have already run, so it's now better to
755   // convert to more optimized IR using more aggressive simplify CFG options.
756   // The extra sinking transform can create larger basic blocks, so do this
757   // before SLP vectorization.
758   MPM.add(createCFGSimplificationPass(1, true, true, false, true));
759 
760   if (SLPVectorize) {
761     MPM.add(createSLPVectorizerPass()); // Vectorize parallel scalar chains.
762     if (OptLevel > 1 && ExtraVectorizerPasses) {
763       MPM.add(createEarlyCSEPass());
764     }
765   }
766 
767   addExtensionsToPM(EP_Peephole, MPM);
768   addInstructionCombiningPass(MPM);
769 
770   if (EnableUnrollAndJam && !DisableUnrollLoops) {
771     // Unroll and Jam. We do this before unroll but need to be in a separate
772     // loop pass manager in order for the outer loop to be processed by
773     // unroll and jam before the inner loop is unrolled.
774     MPM.add(createLoopUnrollAndJamPass(OptLevel));
775   }
776 
777   // Unroll small loops
778   MPM.add(createLoopUnrollPass(OptLevel, DisableUnrollLoops,
779                                ForgetAllSCEVInLoopUnroll));
780 
781   if (!DisableUnrollLoops) {
782     // LoopUnroll may generate some redundency to cleanup.
783     addInstructionCombiningPass(MPM);
784 
785     // Runtime unrolling will introduce runtime check in loop prologue. If the
786     // unrolled loop is a inner loop, then the prologue will be inside the
787     // outer loop. LICM pass can help to promote the runtime check out if the
788     // checked value is loop invariant.
789     MPM.add(createLICMPass(LicmMssaOptCap, LicmMssaNoAccForPromotionCap));
790   }
791 
792   MPM.add(createWarnMissedTransformationsPass());
793 
794   // After vectorization and unrolling, assume intrinsics may tell us more
795   // about pointer alignments.
796   MPM.add(createAlignmentFromAssumptionsPass());
797 
798   // FIXME: We shouldn't bother with this anymore.
799   MPM.add(createStripDeadPrototypesPass()); // Get rid of dead prototypes
800 
801   // GlobalOpt already deletes dead functions and globals, at -O2 try a
802   // late pass of GlobalDCE.  It is capable of deleting dead cycles.
803   if (OptLevel > 1) {
804     MPM.add(createGlobalDCEPass());         // Remove dead fns and globals.
805     MPM.add(createConstantMergePass());     // Merge dup global constants
806   }
807 
808   // See comment in the new PM for justification of scheduling splitting at
809   // this stage (\ref buildModuleSimplificationPipeline).
810   if (EnableHotColdSplit && !(PrepareForLTO || PrepareForThinLTO))
811     MPM.add(createHotColdSplittingPass());
812 
813   if (MergeFunctions)
814     MPM.add(createMergeFunctionsPass());
815 
816   // LoopSink pass sinks instructions hoisted by LICM, which serves as a
817   // canonicalization pass that enables other optimizations. As a result,
818   // LoopSink pass needs to be a very late IR pass to avoid undoing LICM
819   // result too early.
820   MPM.add(createLoopSinkPass());
821   // Get rid of LCSSA nodes.
822   MPM.add(createInstSimplifyLegacyPass());
823 
824   // This hoists/decomposes div/rem ops. It should run after other sink/hoist
825   // passes to avoid re-sinking, but before SimplifyCFG because it can allow
826   // flattening of blocks.
827   MPM.add(createDivRemPairsPass());
828 
829   // LoopSink (and other loop passes since the last simplifyCFG) might have
830   // resulted in single-entry-single-exit or empty blocks. Clean up the CFG.
831   MPM.add(createCFGSimplificationPass());
832 
833   addExtensionsToPM(EP_OptimizerLast, MPM);
834 
835   if (PrepareForLTO) {
836     MPM.add(createCanonicalizeAliasesPass());
837     // Rename anon globals to be able to handle them in the summary
838     MPM.add(createNameAnonGlobalPass());
839   }
840 }
841 
842 void PassManagerBuilder::addLTOOptimizationPasses(legacy::PassManagerBase &PM) {
843   // Load sample profile before running the LTO optimization pipeline.
844   if (!PGOSampleUse.empty()) {
845     PM.add(createPruneEHPass());
846     PM.add(createSampleProfileLoaderPass(PGOSampleUse));
847   }
848 
849   // Remove unused virtual tables to improve the quality of code generated by
850   // whole-program devirtualization and bitset lowering.
851   PM.add(createGlobalDCEPass());
852 
853   // Provide AliasAnalysis services for optimizations.
854   addInitialAliasAnalysisPasses(PM);
855 
856   // Allow forcing function attributes as a debugging and tuning aid.
857   PM.add(createForceFunctionAttrsLegacyPass());
858 
859   // Infer attributes about declarations if possible.
860   PM.add(createInferFunctionAttrsLegacyPass());
861 
862   if (OptLevel > 1) {
863     // Split call-site with more constrained arguments.
864     PM.add(createCallSiteSplittingPass());
865 
866     // Indirect call promotion. This should promote all the targets that are
867     // left by the earlier promotion pass that promotes intra-module targets.
868     // This two-step promotion is to save the compile time. For LTO, it should
869     // produce the same result as if we only do promotion here.
870     PM.add(
871         createPGOIndirectCallPromotionLegacyPass(true, !PGOSampleUse.empty()));
872 
873     // Propagate constants at call sites into the functions they call.  This
874     // opens opportunities for globalopt (and inlining) by substituting function
875     // pointers passed as arguments to direct uses of functions.
876     PM.add(createIPSCCPPass());
877 
878     // Attach metadata to indirect call sites indicating the set of functions
879     // they may target at run-time. This should follow IPSCCP.
880     PM.add(createCalledValuePropagationPass());
881 
882     // Infer attributes on declarations, call sites, arguments, etc.
883     PM.add(createAttributorLegacyPass());
884   }
885 
886   // Infer attributes about definitions. The readnone attribute in particular is
887   // required for virtual constant propagation.
888   PM.add(createPostOrderFunctionAttrsLegacyPass());
889   PM.add(createReversePostOrderFunctionAttrsPass());
890 
891   // Split globals using inrange annotations on GEP indices. This can help
892   // improve the quality of generated code when virtual constant propagation or
893   // control flow integrity are enabled.
894   PM.add(createGlobalSplitPass());
895 
896   // Apply whole-program devirtualization and virtual constant propagation.
897   PM.add(createWholeProgramDevirtPass(ExportSummary, nullptr));
898 
899   // That's all we need at opt level 1.
900   if (OptLevel == 1)
901     return;
902 
903   // Now that we internalized some globals, see if we can hack on them!
904   PM.add(createGlobalOptimizerPass());
905   // Promote any localized global vars.
906   PM.add(createPromoteMemoryToRegisterPass());
907 
908   // Linking modules together can lead to duplicated global constants, only
909   // keep one copy of each constant.
910   PM.add(createConstantMergePass());
911 
912   // Remove unused arguments from functions.
913   PM.add(createDeadArgEliminationPass());
914 
915   // Reduce the code after globalopt and ipsccp.  Both can open up significant
916   // simplification opportunities, and both can propagate functions through
917   // function pointers.  When this happens, we often have to resolve varargs
918   // calls, etc, so let instcombine do this.
919   if (OptLevel > 2)
920     PM.add(createAggressiveInstCombinerPass());
921   addInstructionCombiningPass(PM);
922   addExtensionsToPM(EP_Peephole, PM);
923 
924   // Inline small functions
925   bool RunInliner = Inliner;
926   if (RunInliner) {
927     PM.add(Inliner);
928     Inliner = nullptr;
929   }
930 
931   PM.add(createPruneEHPass());   // Remove dead EH info.
932 
933   // CSFDO instrumentation and use pass.
934   addPGOInstrPasses(PM, /* IsCS */ true);
935 
936   // Optimize globals again if we ran the inliner.
937   if (RunInliner)
938     PM.add(createGlobalOptimizerPass());
939   PM.add(createGlobalDCEPass()); // Remove dead functions.
940 
941   // If we didn't decide to inline a function, check to see if we can
942   // transform it to pass arguments by value instead of by reference.
943   PM.add(createArgumentPromotionPass());
944 
945   // The IPO passes may leave cruft around.  Clean up after them.
946   addInstructionCombiningPass(PM);
947   addExtensionsToPM(EP_Peephole, PM);
948   PM.add(createJumpThreadingPass());
949 
950   // Break up allocas
951   PM.add(createSROAPass());
952 
953   // LTO provides additional opportunities for tailcall elimination due to
954   // link-time inlining, and visibility of nocapture attribute.
955   if (OptLevel > 1)
956     PM.add(createTailCallEliminationPass());
957 
958   // Infer attributes on declarations, call sites, arguments, etc.
959   PM.add(createPostOrderFunctionAttrsLegacyPass()); // Add nocapture.
960   // Run a few AA driven optimizations here and now, to cleanup the code.
961   PM.add(createGlobalsAAWrapperPass()); // IP alias analysis.
962 
963   PM.add(createLICMPass(LicmMssaOptCap, LicmMssaNoAccForPromotionCap));
964   PM.add(createMergedLoadStoreMotionPass()); // Merge ld/st in diamonds.
965   PM.add(NewGVN ? createNewGVNPass()
966                 : createGVNPass(DisableGVNLoadPRE)); // Remove redundancies.
967   PM.add(createMemCpyOptPass());            // Remove dead memcpys.
968 
969   // Nuke dead stores.
970   PM.add(createDeadStoreEliminationPass());
971 
972   // More loops are countable; try to optimize them.
973   PM.add(createIndVarSimplifyPass());
974   PM.add(createLoopDeletionPass());
975   if (EnableLoopInterchange)
976     PM.add(createLoopInterchangePass());
977 
978   // Unroll small loops
979   PM.add(createSimpleLoopUnrollPass(OptLevel, DisableUnrollLoops,
980                                     ForgetAllSCEVInLoopUnroll));
981   PM.add(createLoopVectorizePass(true, !LoopVectorize));
982   // The vectorizer may have significantly shortened a loop body; unroll again.
983   PM.add(createLoopUnrollPass(OptLevel, DisableUnrollLoops,
984                               ForgetAllSCEVInLoopUnroll));
985 
986   PM.add(createWarnMissedTransformationsPass());
987 
988   // Now that we've optimized loops (in particular loop induction variables),
989   // we may have exposed more scalar opportunities. Run parts of the scalar
990   // optimizer again at this point.
991   addInstructionCombiningPass(PM); // Initial cleanup
992   PM.add(createCFGSimplificationPass()); // if-convert
993   PM.add(createSCCPPass()); // Propagate exposed constants
994   addInstructionCombiningPass(PM); // Clean up again
995   PM.add(createBitTrackingDCEPass());
996 
997   // More scalar chains could be vectorized due to more alias information
998   if (SLPVectorize)
999     PM.add(createSLPVectorizerPass()); // Vectorize parallel scalar chains.
1000 
1001   // After vectorization, assume intrinsics may tell us more about pointer
1002   // alignments.
1003   PM.add(createAlignmentFromAssumptionsPass());
1004 
1005   // Cleanup and simplify the code after the scalar optimizations.
1006   addInstructionCombiningPass(PM);
1007   addExtensionsToPM(EP_Peephole, PM);
1008 
1009   PM.add(createJumpThreadingPass());
1010 }
1011 
1012 void PassManagerBuilder::addLateLTOOptimizationPasses(
1013     legacy::PassManagerBase &PM) {
1014   // See comment in the new PM for justification of scheduling splitting at
1015   // this stage (\ref buildLTODefaultPipeline).
1016   if (EnableHotColdSplit)
1017     PM.add(createHotColdSplittingPass());
1018 
1019   // Delete basic blocks, which optimization passes may have killed.
1020   PM.add(createCFGSimplificationPass());
1021 
1022   // Drop bodies of available externally objects to improve GlobalDCE.
1023   PM.add(createEliminateAvailableExternallyPass());
1024 
1025   // Now that we have optimized the program, discard unreachable functions.
1026   PM.add(createGlobalDCEPass());
1027 
1028   // FIXME: this is profitable (for compiler time) to do at -O0 too, but
1029   // currently it damages debug info.
1030   if (MergeFunctions)
1031     PM.add(createMergeFunctionsPass());
1032 }
1033 
1034 void PassManagerBuilder::populateThinLTOPassManager(
1035     legacy::PassManagerBase &PM) {
1036   PerformThinLTO = true;
1037   if (LibraryInfo)
1038     PM.add(new TargetLibraryInfoWrapperPass(*LibraryInfo));
1039 
1040   if (VerifyInput)
1041     PM.add(createVerifierPass());
1042 
1043   if (ImportSummary) {
1044     // This pass imports type identifier resolutions for whole-program
1045     // devirtualization and CFI. It must run early because other passes may
1046     // disturb the specific instruction patterns that these passes look for,
1047     // creating dependencies on resolutions that may not appear in the summary.
1048     //
1049     // For example, GVN may transform the pattern assume(type.test) appearing in
1050     // two basic blocks into assume(phi(type.test, type.test)), which would
1051     // transform a dependency on a WPD resolution into a dependency on a type
1052     // identifier resolution for CFI.
1053     //
1054     // Also, WPD has access to more precise information than ICP and can
1055     // devirtualize more effectively, so it should operate on the IR first.
1056     PM.add(createWholeProgramDevirtPass(nullptr, ImportSummary));
1057     PM.add(createLowerTypeTestsPass(nullptr, ImportSummary));
1058   }
1059 
1060   populateModulePassManager(PM);
1061 
1062   if (VerifyOutput)
1063     PM.add(createVerifierPass());
1064   PerformThinLTO = false;
1065 }
1066 
1067 void PassManagerBuilder::populateLTOPassManager(legacy::PassManagerBase &PM) {
1068   if (LibraryInfo)
1069     PM.add(new TargetLibraryInfoWrapperPass(*LibraryInfo));
1070 
1071   if (VerifyInput)
1072     PM.add(createVerifierPass());
1073 
1074   addExtensionsToPM(EP_FullLinkTimeOptimizationEarly, PM);
1075 
1076   if (OptLevel != 0)
1077     addLTOOptimizationPasses(PM);
1078   else {
1079     // The whole-program-devirt pass needs to run at -O0 because only it knows
1080     // about the llvm.type.checked.load intrinsic: it needs to both lower the
1081     // intrinsic itself and handle it in the summary.
1082     PM.add(createWholeProgramDevirtPass(ExportSummary, nullptr));
1083   }
1084 
1085   // Create a function that performs CFI checks for cross-DSO calls with targets
1086   // in the current module.
1087   PM.add(createCrossDSOCFIPass());
1088 
1089   // Lower type metadata and the type.test intrinsic. This pass supports Clang's
1090   // control flow integrity mechanisms (-fsanitize=cfi*) and needs to run at
1091   // link time if CFI is enabled. The pass does nothing if CFI is disabled.
1092   PM.add(createLowerTypeTestsPass(ExportSummary, nullptr));
1093   // Run a second time to clean up any type tests left behind by WPD for use
1094   // in ICP (which is performed earlier than this in the regular LTO pipeline).
1095   PM.add(createLowerTypeTestsPass(nullptr, nullptr, true));
1096 
1097   if (OptLevel != 0)
1098     addLateLTOOptimizationPasses(PM);
1099 
1100   addExtensionsToPM(EP_FullLinkTimeOptimizationLast, PM);
1101 
1102   if (VerifyOutput)
1103     PM.add(createVerifierPass());
1104 }
1105 
1106 inline PassManagerBuilder *unwrap(LLVMPassManagerBuilderRef P) {
1107     return reinterpret_cast<PassManagerBuilder*>(P);
1108 }
1109 
1110 inline LLVMPassManagerBuilderRef wrap(PassManagerBuilder *P) {
1111   return reinterpret_cast<LLVMPassManagerBuilderRef>(P);
1112 }
1113 
1114 LLVMPassManagerBuilderRef LLVMPassManagerBuilderCreate() {
1115   PassManagerBuilder *PMB = new PassManagerBuilder();
1116   return wrap(PMB);
1117 }
1118 
1119 void LLVMPassManagerBuilderDispose(LLVMPassManagerBuilderRef PMB) {
1120   PassManagerBuilder *Builder = unwrap(PMB);
1121   delete Builder;
1122 }
1123 
1124 void
1125 LLVMPassManagerBuilderSetOptLevel(LLVMPassManagerBuilderRef PMB,
1126                                   unsigned OptLevel) {
1127   PassManagerBuilder *Builder = unwrap(PMB);
1128   Builder->OptLevel = OptLevel;
1129 }
1130 
1131 void
1132 LLVMPassManagerBuilderSetSizeLevel(LLVMPassManagerBuilderRef PMB,
1133                                    unsigned SizeLevel) {
1134   PassManagerBuilder *Builder = unwrap(PMB);
1135   Builder->SizeLevel = SizeLevel;
1136 }
1137 
1138 void
1139 LLVMPassManagerBuilderSetDisableUnitAtATime(LLVMPassManagerBuilderRef PMB,
1140                                             LLVMBool Value) {
1141   // NOTE: The DisableUnitAtATime switch has been removed.
1142 }
1143 
1144 void
1145 LLVMPassManagerBuilderSetDisableUnrollLoops(LLVMPassManagerBuilderRef PMB,
1146                                             LLVMBool Value) {
1147   PassManagerBuilder *Builder = unwrap(PMB);
1148   Builder->DisableUnrollLoops = Value;
1149 }
1150 
1151 void
1152 LLVMPassManagerBuilderSetDisableSimplifyLibCalls(LLVMPassManagerBuilderRef PMB,
1153                                                  LLVMBool Value) {
1154   // NOTE: The simplify-libcalls pass has been removed.
1155 }
1156 
1157 void
1158 LLVMPassManagerBuilderUseInlinerWithThreshold(LLVMPassManagerBuilderRef PMB,
1159                                               unsigned Threshold) {
1160   PassManagerBuilder *Builder = unwrap(PMB);
1161   Builder->Inliner = createFunctionInliningPass(Threshold);
1162 }
1163 
1164 void
1165 LLVMPassManagerBuilderPopulateFunctionPassManager(LLVMPassManagerBuilderRef PMB,
1166                                                   LLVMPassManagerRef PM) {
1167   PassManagerBuilder *Builder = unwrap(PMB);
1168   legacy::FunctionPassManager *FPM = unwrap<legacy::FunctionPassManager>(PM);
1169   Builder->populateFunctionPassManager(*FPM);
1170 }
1171 
1172 void
1173 LLVMPassManagerBuilderPopulateModulePassManager(LLVMPassManagerBuilderRef PMB,
1174                                                 LLVMPassManagerRef PM) {
1175   PassManagerBuilder *Builder = unwrap(PMB);
1176   legacy::PassManagerBase *MPM = unwrap(PM);
1177   Builder->populateModulePassManager(*MPM);
1178 }
1179 
1180 void LLVMPassManagerBuilderPopulateLTOPassManager(LLVMPassManagerBuilderRef PMB,
1181                                                   LLVMPassManagerRef PM,
1182                                                   LLVMBool Internalize,
1183                                                   LLVMBool RunInliner) {
1184   PassManagerBuilder *Builder = unwrap(PMB);
1185   legacy::PassManagerBase *LPM = unwrap(PM);
1186 
1187   // A small backwards compatibility hack. populateLTOPassManager used to take
1188   // an RunInliner option.
1189   if (RunInliner && !Builder->Inliner)
1190     Builder->Inliner = createFunctionInliningPass();
1191 
1192   Builder->populateLTOPassManager(*LPM);
1193 }
1194