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