1 //===- opt.cpp - The LLVM Modular Optimizer -------------------------------===//
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 // Optimizations may be specified an arbitrary number of times on the command
11 // line, They are run in the order specified.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "BreakpointPrinter.h"
16 #include "NewPMDriver.h"
17 #include "PassPrinters.h"
18 #include "llvm/ADT/Triple.h"
19 #include "llvm/Analysis/CallGraph.h"
20 #include "llvm/Analysis/CallGraphSCCPass.h"
21 #include "llvm/Analysis/LoopPass.h"
22 #include "llvm/Analysis/RegionPass.h"
23 #include "llvm/Analysis/TargetLibraryInfo.h"
24 #include "llvm/Analysis/TargetTransformInfo.h"
25 #include "llvm/Bitcode/BitcodeWriterPass.h"
26 #include "llvm/CodeGen/CommandFlags.h"
27 #include "llvm/IR/DataLayout.h"
28 #include "llvm/IR/DebugInfo.h"
29 #include "llvm/IR/IRPrintingPasses.h"
30 #include "llvm/IR/LLVMContext.h"
31 #include "llvm/IR/LegacyPassNameParser.h"
32 #include "llvm/IR/Module.h"
33 #include "llvm/IR/Verifier.h"
34 #include "llvm/IRReader/IRReader.h"
35 #include "llvm/InitializePasses.h"
36 #include "llvm/LinkAllIR.h"
37 #include "llvm/LinkAllPasses.h"
38 #include "llvm/MC/SubtargetFeature.h"
39 #include "llvm/IR/LegacyPassManager.h"
40 #include "llvm/Support/Debug.h"
41 #include "llvm/Support/FileSystem.h"
42 #include "llvm/Support/Host.h"
43 #include "llvm/Support/ManagedStatic.h"
44 #include "llvm/Support/PluginLoader.h"
45 #include "llvm/Support/PrettyStackTrace.h"
46 #include "llvm/Support/Signals.h"
47 #include "llvm/Support/SourceMgr.h"
48 #include "llvm/Support/SystemUtils.h"
49 #include "llvm/Support/TargetRegistry.h"
50 #include "llvm/Support/TargetSelect.h"
51 #include "llvm/Support/ToolOutputFile.h"
52 #include "llvm/Target/TargetMachine.h"
53 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
54 #include <algorithm>
55 #include <memory>
56 using namespace llvm;
57 using namespace opt_tool;
58 
59 // The OptimizationList is automatically populated with registered Passes by the
60 // PassNameParser.
61 //
62 static cl::list<const PassInfo*, bool, PassNameParser>
63 PassList(cl::desc("Optimizations available:"));
64 
65 // This flag specifies a textual description of the optimization pass pipeline
66 // to run over the module. This flag switches opt to use the new pass manager
67 // infrastructure, completely disabling all of the flags specific to the old
68 // pass management.
69 static cl::opt<std::string> PassPipeline(
70     "passes",
71     cl::desc("A textual description of the pass pipeline for optimizing"),
72     cl::Hidden);
73 
74 // Other command line options...
75 //
76 static cl::opt<std::string>
77 InputFilename(cl::Positional, cl::desc("<input bitcode file>"),
78     cl::init("-"), cl::value_desc("filename"));
79 
80 static cl::opt<std::string>
81 OutputFilename("o", cl::desc("Override output filename"),
82                cl::value_desc("filename"));
83 
84 static cl::opt<bool>
85 Force("f", cl::desc("Enable binary output on terminals"));
86 
87 static cl::opt<bool>
88 PrintEachXForm("p", cl::desc("Print module after each transformation"));
89 
90 static cl::opt<bool>
91 NoOutput("disable-output",
92          cl::desc("Do not write result bitcode file"), cl::Hidden);
93 
94 static cl::opt<bool>
95 OutputAssembly("S", cl::desc("Write output as LLVM assembly"));
96 
97 static cl::opt<bool>
98 NoVerify("disable-verify", cl::desc("Do not verify result module"), cl::Hidden);
99 
100 static cl::opt<bool>
101 VerifyEach("verify-each", cl::desc("Verify after each transform"));
102 
103 static cl::opt<bool>
104 StripDebug("strip-debug",
105            cl::desc("Strip debugger symbol info from translation unit"));
106 
107 static cl::opt<bool>
108 DisableInline("disable-inlining", cl::desc("Do not run the inliner pass"));
109 
110 static cl::opt<bool>
111 DisableOptimizations("disable-opt",
112                      cl::desc("Do not run any optimization passes"));
113 
114 static cl::opt<bool>
115 StandardLinkOpts("std-link-opts",
116                  cl::desc("Include the standard link time optimizations"));
117 
118 static cl::opt<bool>
119 OptLevelO1("O1",
120            cl::desc("Optimization level 1. Similar to clang -O1"));
121 
122 static cl::opt<bool>
123 OptLevelO2("O2",
124            cl::desc("Optimization level 2. Similar to clang -O2"));
125 
126 static cl::opt<bool>
127 OptLevelOs("Os",
128            cl::desc("Like -O2 with extra optimizations for size. Similar to clang -Os"));
129 
130 static cl::opt<bool>
131 OptLevelOz("Oz",
132            cl::desc("Like -Os but reduces code size further. Similar to clang -Oz"));
133 
134 static cl::opt<bool>
135 OptLevelO3("O3",
136            cl::desc("Optimization level 3. Similar to clang -O3"));
137 
138 static cl::opt<std::string>
139 TargetTriple("mtriple", cl::desc("Override target triple for module"));
140 
141 static cl::opt<bool>
142 UnitAtATime("funit-at-a-time",
143             cl::desc("Enable IPO. This corresponds to gcc's -funit-at-a-time"),
144             cl::init(true));
145 
146 static cl::opt<bool>
147 DisableLoopUnrolling("disable-loop-unrolling",
148                      cl::desc("Disable loop unrolling in all relevant passes"),
149                      cl::init(false));
150 static cl::opt<bool>
151 DisableLoopVectorization("disable-loop-vectorization",
152                      cl::desc("Disable the loop vectorization pass"),
153                      cl::init(false));
154 
155 static cl::opt<bool>
156 DisableSLPVectorization("disable-slp-vectorization",
157                         cl::desc("Disable the slp vectorization pass"),
158                         cl::init(false));
159 
160 
161 static cl::opt<bool>
162 DisableSimplifyLibCalls("disable-simplify-libcalls",
163                         cl::desc("Disable simplify-libcalls"));
164 
165 static cl::opt<bool>
166 Quiet("q", cl::desc("Obsolete option"), cl::Hidden);
167 
168 static cl::alias
169 QuietA("quiet", cl::desc("Alias for -q"), cl::aliasopt(Quiet));
170 
171 static cl::opt<bool>
172 AnalyzeOnly("analyze", cl::desc("Only perform analysis, no optimization"));
173 
174 static cl::opt<bool>
175 PrintBreakpoints("print-breakpoints-for-testing",
176                  cl::desc("Print select breakpoints location for testing"));
177 
178 static cl::opt<std::string>
179 DefaultDataLayout("default-data-layout",
180           cl::desc("data layout string to use if not specified by module"),
181           cl::value_desc("layout-string"), cl::init(""));
182 
183 static cl::opt<bool> PreserveBitcodeUseListOrder(
184     "preserve-bc-uselistorder",
185     cl::desc("Preserve use-list order when writing LLVM bitcode."),
186     cl::init(true), cl::Hidden);
187 
188 static cl::opt<bool> PreserveAssemblyUseListOrder(
189     "preserve-ll-uselistorder",
190     cl::desc("Preserve use-list order when writing LLVM assembly."),
191     cl::init(false), cl::Hidden);
192 
addPass(legacy::PassManagerBase & PM,Pass * P)193 static inline void addPass(legacy::PassManagerBase &PM, Pass *P) {
194   // Add the pass to the pass manager...
195   PM.add(P);
196 
197   // If we are verifying all of the intermediate steps, add the verifier...
198   if (VerifyEach)
199     PM.add(createVerifierPass());
200 }
201 
202 /// This routine adds optimization passes based on selected optimization level,
203 /// OptLevel.
204 ///
205 /// OptLevel - Optimization Level
AddOptimizationPasses(legacy::PassManagerBase & MPM,legacy::FunctionPassManager & FPM,unsigned OptLevel,unsigned SizeLevel)206 static void AddOptimizationPasses(legacy::PassManagerBase &MPM,
207                                   legacy::FunctionPassManager &FPM,
208                                   unsigned OptLevel, unsigned SizeLevel) {
209   FPM.add(createVerifierPass()); // Verify that input is correct
210 
211   PassManagerBuilder Builder;
212   Builder.OptLevel = OptLevel;
213   Builder.SizeLevel = SizeLevel;
214 
215   if (DisableInline) {
216     // No inlining pass
217   } else if (OptLevel > 1) {
218     Builder.Inliner = createFunctionInliningPass(OptLevel, SizeLevel);
219   } else {
220     Builder.Inliner = createAlwaysInlinerPass();
221   }
222   Builder.DisableUnitAtATime = !UnitAtATime;
223   Builder.DisableUnrollLoops = (DisableLoopUnrolling.getNumOccurrences() > 0) ?
224                                DisableLoopUnrolling : OptLevel == 0;
225 
226   // This is final, unless there is a #pragma vectorize enable
227   if (DisableLoopVectorization)
228     Builder.LoopVectorize = false;
229   // If option wasn't forced via cmd line (-vectorize-loops, -loop-vectorize)
230   else if (!Builder.LoopVectorize)
231     Builder.LoopVectorize = OptLevel > 1 && SizeLevel < 2;
232 
233   // When #pragma vectorize is on for SLP, do the same as above
234   Builder.SLPVectorize =
235       DisableSLPVectorization ? false : OptLevel > 1 && SizeLevel < 2;
236 
237   Builder.populateFunctionPassManager(FPM);
238   Builder.populateModulePassManager(MPM);
239 }
240 
AddStandardLinkPasses(legacy::PassManagerBase & PM)241 static void AddStandardLinkPasses(legacy::PassManagerBase &PM) {
242   PassManagerBuilder Builder;
243   Builder.VerifyInput = true;
244   if (DisableOptimizations)
245     Builder.OptLevel = 0;
246 
247   if (!DisableInline)
248     Builder.Inliner = createFunctionInliningPass();
249   Builder.populateLTOPassManager(PM);
250 }
251 
252 //===----------------------------------------------------------------------===//
253 // CodeGen-related helper functions.
254 //
255 
GetCodeGenOptLevel()256 static CodeGenOpt::Level GetCodeGenOptLevel() {
257   if (OptLevelO1)
258     return CodeGenOpt::Less;
259   if (OptLevelO2)
260     return CodeGenOpt::Default;
261   if (OptLevelO3)
262     return CodeGenOpt::Aggressive;
263   return CodeGenOpt::None;
264 }
265 
266 // Returns the TargetMachine instance or zero if no triple is provided.
GetTargetMachine(Triple TheTriple)267 static TargetMachine* GetTargetMachine(Triple TheTriple) {
268   std::string Error;
269   const Target *TheTarget = TargetRegistry::lookupTarget(MArch, TheTriple,
270                                                          Error);
271   // Some modules don't specify a triple, and this is okay.
272   if (!TheTarget) {
273     return nullptr;
274   }
275 
276   // Package up features to be passed to target/subtarget
277   std::string FeaturesStr;
278   if (MAttrs.size() || MCPU == "native") {
279     SubtargetFeatures Features;
280 
281     // If user asked for the 'native' CPU, we need to autodetect features.
282     // This is necessary for x86 where the CPU might not support all the
283     // features the autodetected CPU name lists in the target. For example,
284     // not all Sandybridge processors support AVX.
285     if (MCPU == "native") {
286       StringMap<bool> HostFeatures;
287       if (sys::getHostCPUFeatures(HostFeatures))
288         for (auto &F : HostFeatures)
289           Features.AddFeature(F.first(), F.second);
290     }
291 
292     for (unsigned i = 0; i != MAttrs.size(); ++i)
293       Features.AddFeature(MAttrs[i]);
294     FeaturesStr = Features.getString();
295   }
296 
297   if (MCPU == "native")
298     MCPU = sys::getHostCPUName();
299 
300   return TheTarget->createTargetMachine(TheTriple.getTriple(),
301                                         MCPU, FeaturesStr,
302                                         InitTargetOptionsFromCodeGenFlags(),
303                                         RelocModel, CMModel,
304                                         GetCodeGenOptLevel());
305 }
306 
307 #ifdef LINK_POLLY_INTO_TOOLS
308 namespace polly {
309 void initializePollyPasses(llvm::PassRegistry &Registry);
310 }
311 #endif
312 
313 //===----------------------------------------------------------------------===//
314 // main for opt
315 //
main(int argc,char ** argv)316 int main(int argc, char **argv) {
317   sys::PrintStackTraceOnErrorSignal();
318   llvm::PrettyStackTraceProgram X(argc, argv);
319 
320   // Enable debug stream buffering.
321   EnableDebugBuffering = true;
322 
323   llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
324   LLVMContext &Context = getGlobalContext();
325 
326   InitializeAllTargets();
327   InitializeAllTargetMCs();
328   InitializeAllAsmPrinters();
329 
330   // Initialize passes
331   PassRegistry &Registry = *PassRegistry::getPassRegistry();
332   initializeCore(Registry);
333   initializeScalarOpts(Registry);
334   initializeObjCARCOpts(Registry);
335   initializeVectorization(Registry);
336   initializeIPO(Registry);
337   initializeAnalysis(Registry);
338   initializeIPA(Registry);
339   initializeTransformUtils(Registry);
340   initializeInstCombine(Registry);
341   initializeInstrumentation(Registry);
342   initializeTarget(Registry);
343   // For codegen passes, only passes that do IR to IR transformation are
344   // supported.
345   initializeCodeGenPreparePass(Registry);
346   initializeAtomicExpandPass(Registry);
347   initializeRewriteSymbolsPass(Registry);
348   initializeWinEHPreparePass(Registry);
349   initializeDwarfEHPreparePass(Registry);
350 
351 #ifdef LINK_POLLY_INTO_TOOLS
352   polly::initializePollyPasses(Registry);
353 #endif
354 
355   cl::ParseCommandLineOptions(argc, argv,
356     "llvm .bc -> .bc modular optimizer and analysis printer\n");
357 
358   if (AnalyzeOnly && NoOutput) {
359     errs() << argv[0] << ": analyze mode conflicts with no-output mode.\n";
360     return 1;
361   }
362 
363   SMDiagnostic Err;
364 
365   // Load the input module...
366   std::unique_ptr<Module> M = parseIRFile(InputFilename, Err, Context);
367 
368   if (!M) {
369     Err.print(argv[0], errs());
370     return 1;
371   }
372 
373   // Strip debug info before running the verifier.
374   if (StripDebug)
375     StripDebugInfo(*M);
376 
377   // Immediately run the verifier to catch any problems before starting up the
378   // pass pipelines.  Otherwise we can crash on broken code during
379   // doInitialization().
380   if (!NoVerify && verifyModule(*M, &errs())) {
381     errs() << argv[0] << ": " << InputFilename
382            << ": error: input module is broken!\n";
383     return 1;
384   }
385 
386   // If we are supposed to override the target triple, do so now.
387   if (!TargetTriple.empty())
388     M->setTargetTriple(Triple::normalize(TargetTriple));
389 
390   // Figure out what stream we are supposed to write to...
391   std::unique_ptr<tool_output_file> Out;
392   if (NoOutput) {
393     if (!OutputFilename.empty())
394       errs() << "WARNING: The -o (output filename) option is ignored when\n"
395                 "the --disable-output option is used.\n";
396   } else {
397     // Default to standard output.
398     if (OutputFilename.empty())
399       OutputFilename = "-";
400 
401     std::error_code EC;
402     Out.reset(new tool_output_file(OutputFilename, EC, sys::fs::F_None));
403     if (EC) {
404       errs() << EC.message() << '\n';
405       return 1;
406     }
407   }
408 
409   Triple ModuleTriple(M->getTargetTriple());
410   TargetMachine *Machine = nullptr;
411   if (ModuleTriple.getArch())
412     Machine = GetTargetMachine(ModuleTriple);
413   std::unique_ptr<TargetMachine> TM(Machine);
414 
415   // If the output is set to be emitted to standard out, and standard out is a
416   // console, print out a warning message and refuse to do it.  We don't
417   // impress anyone by spewing tons of binary goo to a terminal.
418   if (!Force && !NoOutput && !AnalyzeOnly && !OutputAssembly)
419     if (CheckBitcodeOutputToConsole(Out->os(), !Quiet))
420       NoOutput = true;
421 
422   if (PassPipeline.getNumOccurrences() > 0) {
423     OutputKind OK = OK_NoOutput;
424     if (!NoOutput)
425       OK = OutputAssembly ? OK_OutputAssembly : OK_OutputBitcode;
426 
427     VerifierKind VK = VK_VerifyInAndOut;
428     if (NoVerify)
429       VK = VK_NoVerifier;
430     else if (VerifyEach)
431       VK = VK_VerifyEachPass;
432 
433     // The user has asked to use the new pass manager and provided a pipeline
434     // string. Hand off the rest of the functionality to the new code for that
435     // layer.
436     return runPassPipeline(argv[0], Context, *M, TM.get(), Out.get(),
437                            PassPipeline, OK, VK, PreserveAssemblyUseListOrder,
438                            PreserveBitcodeUseListOrder)
439                ? 0
440                : 1;
441   }
442 
443   // Create a PassManager to hold and optimize the collection of passes we are
444   // about to build.
445   //
446   legacy::PassManager Passes;
447 
448   // Add an appropriate TargetLibraryInfo pass for the module's triple.
449   TargetLibraryInfoImpl TLII(ModuleTriple);
450 
451   // The -disable-simplify-libcalls flag actually disables all builtin optzns.
452   if (DisableSimplifyLibCalls)
453     TLII.disableAllFunctions();
454   Passes.add(new TargetLibraryInfoWrapperPass(TLII));
455 
456   // Add an appropriate DataLayout instance for this module.
457   const DataLayout &DL = M->getDataLayout();
458   if (DL.isDefault() && !DefaultDataLayout.empty()) {
459     M->setDataLayout(DefaultDataLayout);
460   }
461 
462   // Add internal analysis passes from the target machine.
463   Passes.add(createTargetTransformInfoWrapperPass(TM ? TM->getTargetIRAnalysis()
464                                                      : TargetIRAnalysis()));
465 
466   std::unique_ptr<legacy::FunctionPassManager> FPasses;
467   if (OptLevelO1 || OptLevelO2 || OptLevelOs || OptLevelOz || OptLevelO3) {
468     FPasses.reset(new legacy::FunctionPassManager(M.get()));
469     FPasses->add(createTargetTransformInfoWrapperPass(
470         TM ? TM->getTargetIRAnalysis() : TargetIRAnalysis()));
471   }
472 
473   if (PrintBreakpoints) {
474     // Default to standard output.
475     if (!Out) {
476       if (OutputFilename.empty())
477         OutputFilename = "-";
478 
479       std::error_code EC;
480       Out = llvm::make_unique<tool_output_file>(OutputFilename, EC,
481                                                 sys::fs::F_None);
482       if (EC) {
483         errs() << EC.message() << '\n';
484         return 1;
485       }
486     }
487     Passes.add(createBreakpointPrinter(Out->os()));
488     NoOutput = true;
489   }
490 
491   // Create a new optimization pass for each one specified on the command line
492   for (unsigned i = 0; i < PassList.size(); ++i) {
493     if (StandardLinkOpts &&
494         StandardLinkOpts.getPosition() < PassList.getPosition(i)) {
495       AddStandardLinkPasses(Passes);
496       StandardLinkOpts = false;
497     }
498 
499     if (OptLevelO1 && OptLevelO1.getPosition() < PassList.getPosition(i)) {
500       AddOptimizationPasses(Passes, *FPasses, 1, 0);
501       OptLevelO1 = false;
502     }
503 
504     if (OptLevelO2 && OptLevelO2.getPosition() < PassList.getPosition(i)) {
505       AddOptimizationPasses(Passes, *FPasses, 2, 0);
506       OptLevelO2 = false;
507     }
508 
509     if (OptLevelOs && OptLevelOs.getPosition() < PassList.getPosition(i)) {
510       AddOptimizationPasses(Passes, *FPasses, 2, 1);
511       OptLevelOs = false;
512     }
513 
514     if (OptLevelOz && OptLevelOz.getPosition() < PassList.getPosition(i)) {
515       AddOptimizationPasses(Passes, *FPasses, 2, 2);
516       OptLevelOz = false;
517     }
518 
519     if (OptLevelO3 && OptLevelO3.getPosition() < PassList.getPosition(i)) {
520       AddOptimizationPasses(Passes, *FPasses, 3, 0);
521       OptLevelO3 = false;
522     }
523 
524     const PassInfo *PassInf = PassList[i];
525     Pass *P = nullptr;
526     if (PassInf->getTargetMachineCtor())
527       P = PassInf->getTargetMachineCtor()(TM.get());
528     else if (PassInf->getNormalCtor())
529       P = PassInf->getNormalCtor()();
530     else
531       errs() << argv[0] << ": cannot create pass: "
532              << PassInf->getPassName() << "\n";
533     if (P) {
534       PassKind Kind = P->getPassKind();
535       addPass(Passes, P);
536 
537       if (AnalyzeOnly) {
538         switch (Kind) {
539         case PT_BasicBlock:
540           Passes.add(createBasicBlockPassPrinter(PassInf, Out->os(), Quiet));
541           break;
542         case PT_Region:
543           Passes.add(createRegionPassPrinter(PassInf, Out->os(), Quiet));
544           break;
545         case PT_Loop:
546           Passes.add(createLoopPassPrinter(PassInf, Out->os(), Quiet));
547           break;
548         case PT_Function:
549           Passes.add(createFunctionPassPrinter(PassInf, Out->os(), Quiet));
550           break;
551         case PT_CallGraphSCC:
552           Passes.add(createCallGraphPassPrinter(PassInf, Out->os(), Quiet));
553           break;
554         default:
555           Passes.add(createModulePassPrinter(PassInf, Out->os(), Quiet));
556           break;
557         }
558       }
559     }
560 
561     if (PrintEachXForm)
562       Passes.add(
563           createPrintModulePass(errs(), "", PreserveAssemblyUseListOrder));
564   }
565 
566   if (StandardLinkOpts) {
567     AddStandardLinkPasses(Passes);
568     StandardLinkOpts = false;
569   }
570 
571   if (OptLevelO1)
572     AddOptimizationPasses(Passes, *FPasses, 1, 0);
573 
574   if (OptLevelO2)
575     AddOptimizationPasses(Passes, *FPasses, 2, 0);
576 
577   if (OptLevelOs)
578     AddOptimizationPasses(Passes, *FPasses, 2, 1);
579 
580   if (OptLevelOz)
581     AddOptimizationPasses(Passes, *FPasses, 2, 2);
582 
583   if (OptLevelO3)
584     AddOptimizationPasses(Passes, *FPasses, 3, 0);
585 
586   if (OptLevelO1 || OptLevelO2 || OptLevelOs || OptLevelOz || OptLevelO3) {
587     FPasses->doInitialization();
588     for (Function &F : *M)
589       FPasses->run(F);
590     FPasses->doFinalization();
591   }
592 
593   // Check that the module is well formed on completion of optimization
594   if (!NoVerify && !VerifyEach)
595     Passes.add(createVerifierPass());
596 
597   // Write bitcode or assembly to the output as the last step...
598   if (!NoOutput && !AnalyzeOnly) {
599     if (OutputAssembly)
600       Passes.add(
601           createPrintModulePass(Out->os(), "", PreserveAssemblyUseListOrder));
602     else
603       Passes.add(
604           createBitcodeWriterPass(Out->os(), PreserveBitcodeUseListOrder));
605   }
606 
607   // Before executing passes, print the final values of the LLVM options.
608   cl::PrintOptionValues();
609 
610   // Now that we have all of the passes ready, run them.
611   Passes.run(*M);
612 
613   // Declare success.
614   if (!NoOutput || PrintBreakpoints)
615     Out->keep();
616 
617   return 0;
618 }
619