1 //===-- Passes.cpp - Target independent code generation passes ------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines interfaces to access the target independent code
11 // generation passes provided by the LLVM backend.
13 //===---------------------------------------------------------------------===//
15 #include "llvm/CodeGen/Passes.h"
16 #include "llvm/Analysis/BasicAliasAnalysis.h"
17 #include "llvm/Analysis/CFLAliasAnalysis.h"
18 #include "llvm/Analysis/Passes.h"
19 #include "llvm/Analysis/ScopedNoAliasAA.h"
20 #include "llvm/Analysis/TypeBasedAliasAnalysis.h"
21 #include "llvm/CodeGen/MachineFunctionPass.h"
22 #include "llvm/CodeGen/RegAllocRegistry.h"
23 #include "llvm/IR/IRPrintingPasses.h"
24 #include "llvm/IR/LegacyPassManager.h"
25 #include "llvm/IR/Verifier.h"
26 #include "llvm/MC/MCAsmInfo.h"
27 #include "llvm/Support/CommandLine.h"
28 #include "llvm/Support/Debug.h"
29 #include "llvm/Support/ErrorHandling.h"
30 #include "llvm/Support/raw_ostream.h"
31 #include "llvm/Transforms/Instrumentation.h"
32 #include "llvm/Transforms/Scalar.h"
33 #include "llvm/Transforms/Utils/SymbolRewriter.h"
37 static cl::opt<bool> DisablePostRA("disable-post-ra", cl::Hidden,
38 cl::desc("Disable Post Regalloc"));
39 static cl::opt<bool> DisableBranchFold("disable-branch-fold", cl::Hidden,
40 cl::desc("Disable branch folding"));
41 static cl::opt<bool> DisableTailDuplicate("disable-tail-duplicate", cl::Hidden,
42 cl::desc("Disable tail duplication"));
43 static cl::opt<bool> DisableEarlyTailDup("disable-early-taildup", cl::Hidden,
44 cl::desc("Disable pre-register allocation tail duplication"));
45 static cl::opt<bool> DisableBlockPlacement("disable-block-placement",
46 cl::Hidden, cl::desc("Disable probability-driven block placement"));
47 static cl::opt<bool> EnableBlockPlacementStats("enable-block-placement-stats",
48 cl::Hidden, cl::desc("Collect probability-driven block placement stats"));
49 static cl::opt<bool> DisableSSC("disable-ssc", cl::Hidden,
50 cl::desc("Disable Stack Slot Coloring"));
51 static cl::opt<bool> DisableMachineDCE("disable-machine-dce", cl::Hidden,
52 cl::desc("Disable Machine Dead Code Elimination"));
53 static cl::opt<bool> DisableEarlyIfConversion("disable-early-ifcvt", cl::Hidden,
54 cl::desc("Disable Early If-conversion"));
55 static cl::opt<bool> DisableMachineLICM("disable-machine-licm", cl::Hidden,
56 cl::desc("Disable Machine LICM"));
57 static cl::opt<bool> DisableMachineCSE("disable-machine-cse", cl::Hidden,
58 cl::desc("Disable Machine Common Subexpression Elimination"));
59 static cl::opt<cl::boolOrDefault> OptimizeRegAlloc(
60 "optimize-regalloc", cl::Hidden,
61 cl::desc("Enable optimized register allocation compilation path."));
62 static cl::opt<bool> DisablePostRAMachineLICM("disable-postra-machine-licm",
64 cl::desc("Disable Machine LICM"));
65 static cl::opt<bool> DisableMachineSink("disable-machine-sink", cl::Hidden,
66 cl::desc("Disable Machine Sinking"));
67 static cl::opt<bool> DisableLSR("disable-lsr", cl::Hidden,
68 cl::desc("Disable Loop Strength Reduction Pass"));
69 static cl::opt<bool> DisableConstantHoisting("disable-constant-hoisting",
70 cl::Hidden, cl::desc("Disable ConstantHoisting"));
71 static cl::opt<bool> DisableCGP("disable-cgp", cl::Hidden,
72 cl::desc("Disable Codegen Prepare"));
73 static cl::opt<bool> DisableCopyProp("disable-copyprop", cl::Hidden,
74 cl::desc("Disable Copy Propagation pass"));
75 static cl::opt<bool> DisablePartialLibcallInlining("disable-partial-libcall-inlining",
76 cl::Hidden, cl::desc("Disable Partial Libcall Inlining"));
77 static cl::opt<bool> EnableImplicitNullChecks(
78 "enable-implicit-null-checks",
79 cl::desc("Fold null checks into faulting memory operations"),
81 static cl::opt<bool> PrintLSR("print-lsr-output", cl::Hidden,
82 cl::desc("Print LLVM IR produced by the loop-reduce pass"));
83 static cl::opt<bool> PrintISelInput("print-isel-input", cl::Hidden,
84 cl::desc("Print LLVM IR input to isel pass"));
85 static cl::opt<bool> PrintGCInfo("print-gc", cl::Hidden,
86 cl::desc("Dump garbage collector data"));
87 static cl::opt<bool> VerifyMachineCode("verify-machineinstrs", cl::Hidden,
88 cl::desc("Verify generated machine code"),
92 static cl::opt<std::string>
93 PrintMachineInstrs("print-machineinstrs", cl::ValueOptional,
94 cl::desc("Print machine instrs"),
95 cl::value_desc("pass-name"), cl::init("option-unspecified"));
97 // Temporary option to allow experimenting with MachineScheduler as a post-RA
98 // scheduler. Targets can "properly" enable this with
99 // substitutePass(&PostRASchedulerID, &PostMachineSchedulerID); Ideally it
100 // wouldn't be part of the standard pass pipeline, and the target would just add
101 // a PostRA scheduling pass wherever it wants.
102 static cl::opt<bool> MISchedPostRA("misched-postra", cl::Hidden,
103 cl::desc("Run MachineScheduler post regalloc (independent of preRA sched)"));
105 // Experimental option to run live interval analysis early.
106 static cl::opt<bool> EarlyLiveIntervals("early-live-intervals", cl::Hidden,
107 cl::desc("Run live interval analysis earlier in the pipeline"));
109 static cl::opt<bool> UseCFLAA("use-cfl-aa-in-codegen",
110 cl::init(false), cl::Hidden,
111 cl::desc("Enable the new, experimental CFL alias analysis in CodeGen"));
113 /// Allow standard passes to be disabled by command line options. This supports
114 /// simple binary flags that either suppress the pass or do nothing.
115 /// i.e. -disable-mypass=false has no effect.
116 /// These should be converted to boolOrDefault in order to use applyOverride.
117 static IdentifyingPassPtr applyDisable(IdentifyingPassPtr PassID,
120 return IdentifyingPassPtr();
124 /// Allow standard passes to be disabled by the command line, regardless of who
125 /// is adding the pass.
127 /// StandardID is the pass identified in the standard pass pipeline and provided
128 /// to addPass(). It may be a target-specific ID in the case that the target
129 /// directly adds its own pass, but in that case we harmlessly fall through.
131 /// TargetID is the pass that the target has configured to override StandardID.
133 /// StandardID may be a pseudo ID. In that case TargetID is the name of the real
134 /// pass to run. This allows multiple options to control a single pass depending
135 /// on where in the pipeline that pass is added.
136 static IdentifyingPassPtr overridePass(AnalysisID StandardID,
137 IdentifyingPassPtr TargetID) {
138 if (StandardID == &PostRASchedulerID)
139 return applyDisable(TargetID, DisablePostRA);
141 if (StandardID == &BranchFolderPassID)
142 return applyDisable(TargetID, DisableBranchFold);
144 if (StandardID == &TailDuplicateID)
145 return applyDisable(TargetID, DisableTailDuplicate);
147 if (StandardID == &TargetPassConfig::EarlyTailDuplicateID)
148 return applyDisable(TargetID, DisableEarlyTailDup);
150 if (StandardID == &MachineBlockPlacementID)
151 return applyDisable(TargetID, DisableBlockPlacement);
153 if (StandardID == &StackSlotColoringID)
154 return applyDisable(TargetID, DisableSSC);
156 if (StandardID == &DeadMachineInstructionElimID)
157 return applyDisable(TargetID, DisableMachineDCE);
159 if (StandardID == &EarlyIfConverterID)
160 return applyDisable(TargetID, DisableEarlyIfConversion);
162 if (StandardID == &MachineLICMID)
163 return applyDisable(TargetID, DisableMachineLICM);
165 if (StandardID == &MachineCSEID)
166 return applyDisable(TargetID, DisableMachineCSE);
168 if (StandardID == &TargetPassConfig::PostRAMachineLICMID)
169 return applyDisable(TargetID, DisablePostRAMachineLICM);
171 if (StandardID == &MachineSinkingID)
172 return applyDisable(TargetID, DisableMachineSink);
174 if (StandardID == &MachineCopyPropagationID)
175 return applyDisable(TargetID, DisableCopyProp);
180 //===---------------------------------------------------------------------===//
182 //===---------------------------------------------------------------------===//
184 INITIALIZE_PASS(TargetPassConfig, "targetpassconfig",
185 "Target Pass Configuration", false, false)
186 char TargetPassConfig::ID = 0;
189 char TargetPassConfig::EarlyTailDuplicateID = 0;
190 char TargetPassConfig::PostRAMachineLICMID = 0;
193 struct InsertedPass {
194 AnalysisID TargetPassID;
195 IdentifyingPassPtr InsertedPassID;
199 InsertedPass(AnalysisID TargetPassID, IdentifyingPassPtr InsertedPassID,
200 bool VerifyAfter, bool PrintAfter)
201 : TargetPassID(TargetPassID), InsertedPassID(InsertedPassID),
202 VerifyAfter(VerifyAfter), PrintAfter(PrintAfter) {}
204 Pass *getInsertedPass() const {
205 assert(InsertedPassID.isValid() && "Illegal Pass ID!");
206 if (InsertedPassID.isInstance())
207 return InsertedPassID.getInstance();
208 Pass *NP = Pass::createPass(InsertedPassID.getID());
209 assert(NP && "Pass ID not registered");
216 class PassConfigImpl {
218 // List of passes explicitly substituted by this target. Normally this is
219 // empty, but it is a convenient way to suppress or replace specific passes
220 // that are part of a standard pass pipeline without overridding the entire
221 // pipeline. This mechanism allows target options to inherit a standard pass's
222 // user interface. For example, a target may disable a standard pass by
223 // default by substituting a pass ID of zero, and the user may still enable
224 // that standard pass with an explicit command line option.
225 DenseMap<AnalysisID,IdentifyingPassPtr> TargetPasses;
227 /// Store the pairs of <AnalysisID, AnalysisID> of which the second pass
228 /// is inserted after each instance of the first one.
229 SmallVector<InsertedPass, 4> InsertedPasses;
233 // Out of line virtual method.
234 TargetPassConfig::~TargetPassConfig() {
238 // Out of line constructor provides default values for pass options and
239 // registers all common codegen passes.
240 TargetPassConfig::TargetPassConfig(TargetMachine *tm, PassManagerBase &pm)
241 : ImmutablePass(ID), PM(&pm), StartBefore(nullptr), StartAfter(nullptr),
242 StopAfter(nullptr), Started(true), Stopped(false),
243 AddingMachinePasses(false), TM(tm), Impl(nullptr), Initialized(false),
244 DisableVerify(false), EnableTailMerge(true) {
246 Impl = new PassConfigImpl();
248 // Register all target independent codegen passes to activate their PassIDs,
249 // including this pass itself.
250 initializeCodeGen(*PassRegistry::getPassRegistry());
252 // Also register alias analysis passes required by codegen passes.
253 initializeBasicAAWrapperPassPass(*PassRegistry::getPassRegistry());
254 initializeAAResultsWrapperPassPass(*PassRegistry::getPassRegistry());
256 // Substitute Pseudo Pass IDs for real ones.
257 substitutePass(&EarlyTailDuplicateID, &TailDuplicateID);
258 substitutePass(&PostRAMachineLICMID, &MachineLICMID);
261 /// Insert InsertedPassID pass after TargetPassID.
262 void TargetPassConfig::insertPass(AnalysisID TargetPassID,
263 IdentifyingPassPtr InsertedPassID,
264 bool VerifyAfter, bool PrintAfter) {
265 assert(((!InsertedPassID.isInstance() &&
266 TargetPassID != InsertedPassID.getID()) ||
267 (InsertedPassID.isInstance() &&
268 TargetPassID != InsertedPassID.getInstance()->getPassID())) &&
269 "Insert a pass after itself!");
270 Impl->InsertedPasses.emplace_back(TargetPassID, InsertedPassID, VerifyAfter,
274 /// createPassConfig - Create a pass configuration object to be used by
275 /// addPassToEmitX methods for generating a pipeline of CodeGen passes.
277 /// Targets may override this to extend TargetPassConfig.
278 TargetPassConfig *LLVMTargetMachine::createPassConfig(PassManagerBase &PM) {
279 return new TargetPassConfig(this, PM);
282 TargetPassConfig::TargetPassConfig()
283 : ImmutablePass(ID), PM(nullptr) {
284 llvm_unreachable("TargetPassConfig should not be constructed on-the-fly");
287 // Helper to verify the analysis is really immutable.
288 void TargetPassConfig::setOpt(bool &Opt, bool Val) {
289 assert(!Initialized && "PassConfig is immutable");
293 void TargetPassConfig::substitutePass(AnalysisID StandardID,
294 IdentifyingPassPtr TargetID) {
295 Impl->TargetPasses[StandardID] = TargetID;
298 IdentifyingPassPtr TargetPassConfig::getPassSubstitution(AnalysisID ID) const {
299 DenseMap<AnalysisID, IdentifyingPassPtr>::const_iterator
300 I = Impl->TargetPasses.find(ID);
301 if (I == Impl->TargetPasses.end())
306 /// Add a pass to the PassManager if that pass is supposed to be run. If the
307 /// Started/Stopped flags indicate either that the compilation should start at
308 /// a later pass or that it should stop after an earlier pass, then do not add
309 /// the pass. Finally, compare the current pass against the StartAfter
310 /// and StopAfter options and change the Started/Stopped flags accordingly.
311 void TargetPassConfig::addPass(Pass *P, bool verifyAfter, bool printAfter) {
312 assert(!Initialized && "PassConfig is immutable");
314 // Cache the Pass ID here in case the pass manager finds this pass is
315 // redundant with ones already scheduled / available, and deletes it.
316 // Fundamentally, once we add the pass to the manager, we no longer own it
317 // and shouldn't reference it.
318 AnalysisID PassID = P->getPassID();
320 if (StartBefore == PassID)
322 if (Started && !Stopped) {
324 // Construct banner message before PM->add() as that may delete the pass.
325 if (AddingMachinePasses && (printAfter || verifyAfter))
326 Banner = std::string("After ") + std::string(P->getPassName());
328 if (AddingMachinePasses) {
330 addPrintPass(Banner);
332 addVerifyPass(Banner);
335 // Add the passes after the pass P if there is any.
336 for (auto IP : Impl->InsertedPasses) {
337 if (IP.TargetPassID == PassID)
338 addPass(IP.getInsertedPass(), IP.VerifyAfter, IP.PrintAfter);
343 if (StopAfter == PassID)
345 if (StartAfter == PassID)
347 if (Stopped && !Started)
348 report_fatal_error("Cannot stop compilation after pass that is not run");
351 /// Add a CodeGen pass at this point in the pipeline after checking for target
352 /// and command line overrides.
354 /// addPass cannot return a pointer to the pass instance because is internal the
355 /// PassManager and the instance we create here may already be freed.
356 AnalysisID TargetPassConfig::addPass(AnalysisID PassID, bool verifyAfter,
358 IdentifyingPassPtr TargetID = getPassSubstitution(PassID);
359 IdentifyingPassPtr FinalPtr = overridePass(PassID, TargetID);
360 if (!FinalPtr.isValid())
364 if (FinalPtr.isInstance())
365 P = FinalPtr.getInstance();
367 P = Pass::createPass(FinalPtr.getID());
369 llvm_unreachable("Pass ID not registered");
371 AnalysisID FinalID = P->getPassID();
372 addPass(P, verifyAfter, printAfter); // Ends the lifetime of P.
377 void TargetPassConfig::printAndVerify(const std::string &Banner) {
378 addPrintPass(Banner);
379 addVerifyPass(Banner);
382 void TargetPassConfig::addPrintPass(const std::string &Banner) {
383 if (TM->shouldPrintMachineCode())
384 PM->add(createMachineFunctionPrinterPass(dbgs(), Banner));
387 void TargetPassConfig::addVerifyPass(const std::string &Banner) {
388 if (VerifyMachineCode)
389 PM->add(createMachineVerifierPass(Banner));
392 /// Add common target configurable passes that perform LLVM IR to IR transforms
393 /// following machine independent optimization.
394 void TargetPassConfig::addIRPasses() {
395 // Basic AliasAnalysis support.
396 // Add TypeBasedAliasAnalysis before BasicAliasAnalysis so that
397 // BasicAliasAnalysis wins if they disagree. This is intended to help
398 // support "obvious" type-punning idioms.
400 addPass(createCFLAAWrapperPass());
401 addPass(createTypeBasedAAWrapperPass());
402 addPass(createScopedNoAliasAAWrapperPass());
403 addPass(createBasicAAWrapperPass());
405 // Before running any passes, run the verifier to determine if the input
406 // coming from the front-end and/or optimizer is valid.
408 addPass(createVerifierPass());
410 // Run loop strength reduction before anything else.
411 if (getOptLevel() != CodeGenOpt::None && !DisableLSR) {
412 addPass(createLoopStrengthReducePass());
414 addPass(createPrintFunctionPass(dbgs(), "\n\n*** Code after LSR ***\n"));
417 // Run GC lowering passes for builtin collectors
418 // TODO: add a pass insertion point here
419 addPass(createGCLoweringPass());
420 addPass(createShadowStackGCLoweringPass());
422 // Make sure that no unreachable blocks are instruction selected.
423 addPass(createUnreachableBlockEliminationPass());
425 // Prepare expensive constants for SelectionDAG.
426 if (getOptLevel() != CodeGenOpt::None && !DisableConstantHoisting)
427 addPass(createConstantHoistingPass());
429 if (getOptLevel() != CodeGenOpt::None && !DisablePartialLibcallInlining)
430 addPass(createPartiallyInlineLibCallsPass());
433 /// Turn exception handling constructs into something the code generators can
435 void TargetPassConfig::addPassesToHandleExceptions() {
436 switch (TM->getMCAsmInfo()->getExceptionHandlingType()) {
437 case ExceptionHandling::SjLj:
438 // SjLj piggy-backs on dwarf for this bit. The cleanups done apply to both
439 // Dwarf EH prepare needs to be run after SjLj prepare. Otherwise,
440 // catch info can get misplaced when a selector ends up more than one block
441 // removed from the parent invoke(s). This could happen when a landing
442 // pad is shared by multiple invokes and is also a target of a normal
443 // edge from elsewhere.
444 addPass(createSjLjEHPreparePass());
446 case ExceptionHandling::DwarfCFI:
447 case ExceptionHandling::ARM:
448 addPass(createDwarfEHPass(TM));
450 case ExceptionHandling::WinEH:
451 // We support using both GCC-style and MSVC-style exceptions on Windows, so
452 // add both preparation passes. Each pass will only actually run if it
453 // recognizes the personality function.
454 addPass(createWinEHPass(TM));
455 addPass(createDwarfEHPass(TM));
457 case ExceptionHandling::None:
458 addPass(createLowerInvokePass());
460 // The lower invoke pass may create unreachable code. Remove it.
461 addPass(createUnreachableBlockEliminationPass());
466 /// Add pass to prepare the LLVM IR for code generation. This should be done
467 /// before exception handling preparation passes.
468 void TargetPassConfig::addCodeGenPrepare() {
469 if (getOptLevel() != CodeGenOpt::None && !DisableCGP)
470 addPass(createCodeGenPreparePass(TM));
471 addPass(createRewriteSymbolsPass());
474 /// Add common passes that perform LLVM IR to IR transforms in preparation for
475 /// instruction selection.
476 void TargetPassConfig::addISelPrepare() {
479 // Add both the safe stack and the stack protection passes: each of them will
480 // only protect functions that have corresponding attributes.
481 addPass(createSafeStackPass(TM));
482 addPass(createStackProtectorPass(TM));
485 addPass(createPrintFunctionPass(
486 dbgs(), "\n\n*** Final LLVM Code input to ISel ***\n"));
488 // All passes which modify the LLVM IR are now complete; run the verifier
489 // to ensure that the IR is valid.
491 addPass(createVerifierPass());
494 /// Add the complete set of target-independent postISel code generator passes.
496 /// This can be read as the standard order of major LLVM CodeGen stages. Stages
497 /// with nontrivial configuration or multiple passes are broken out below in
498 /// add%Stage routines.
500 /// Any TargetPassConfig::addXX routine may be overriden by the Target. The
501 /// addPre/Post methods with empty header implementations allow injecting
502 /// target-specific fixups just before or after major stages. Additionally,
503 /// targets have the flexibility to change pass order within a stage by
504 /// overriding default implementation of add%Stage routines below. Each
505 /// technique has maintainability tradeoffs because alternate pass orders are
506 /// not well supported. addPre/Post works better if the target pass is easily
507 /// tied to a common pass. But if it has subtle dependencies on multiple passes,
508 /// the target should override the stage instead.
510 /// TODO: We could use a single addPre/Post(ID) hook to allow pass injection
511 /// before/after any target-independent pass. But it's currently overkill.
512 void TargetPassConfig::addMachinePasses() {
513 AddingMachinePasses = true;
515 // Insert a machine instr printer pass after the specified pass.
516 // If -print-machineinstrs specified, print machineinstrs after all passes.
517 if (StringRef(PrintMachineInstrs.getValue()).equals(""))
518 TM->Options.PrintMachineCode = true;
519 else if (!StringRef(PrintMachineInstrs.getValue())
520 .equals("option-unspecified")) {
521 const PassRegistry *PR = PassRegistry::getPassRegistry();
522 const PassInfo *TPI = PR->getPassInfo(PrintMachineInstrs.getValue());
523 const PassInfo *IPI = PR->getPassInfo(StringRef("machineinstr-printer"));
524 assert (TPI && IPI && "Pass ID not registered!");
525 const char *TID = (const char *)(TPI->getTypeInfo());
526 const char *IID = (const char *)(IPI->getTypeInfo());
527 insertPass(TID, IID);
530 // Print the instruction selected machine code...
531 printAndVerify("After Instruction Selection");
533 // Expand pseudo-instructions emitted by ISel.
534 addPass(&ExpandISelPseudosID);
536 // Add passes that optimize machine instructions in SSA form.
537 if (getOptLevel() != CodeGenOpt::None) {
538 addMachineSSAOptimization();
540 // If the target requests it, assign local variables to stack slots relative
541 // to one another and simplify frame index references where possible.
542 addPass(&LocalStackSlotAllocationID, false);
545 // Run pre-ra passes.
548 // Run register allocation and passes that are tightly coupled with it,
549 // including phi elimination and scheduling.
550 if (getOptimizeRegAlloc())
551 addOptimizedRegAlloc(createRegAllocPass(true));
553 addFastRegAlloc(createRegAllocPass(false));
555 // Run post-ra passes.
558 // Insert prolog/epilog code. Eliminate abstract frame index references...
559 if (getOptLevel() != CodeGenOpt::None)
560 addPass(&ShrinkWrapID);
562 addPass(&PrologEpilogCodeInserterID);
564 /// Add passes that optimize machine instructions after register allocation.
565 if (getOptLevel() != CodeGenOpt::None)
566 addMachineLateOptimization();
568 // Expand pseudo instructions before second scheduling pass.
569 addPass(&ExpandPostRAPseudosID);
571 // Run pre-sched2 passes.
574 if (EnableImplicitNullChecks)
575 addPass(&ImplicitNullChecksID);
577 // Second pass scheduler.
578 if (getOptLevel() != CodeGenOpt::None) {
580 addPass(&PostMachineSchedulerID);
582 addPass(&PostRASchedulerID);
588 addPass(createGCInfoPrinter(dbgs()), false, false);
591 // Basic block placement.
592 if (getOptLevel() != CodeGenOpt::None)
597 addPass(&FuncletLayoutID, false);
599 addPass(&StackMapLivenessID, false);
601 AddingMachinePasses = false;
604 /// Add passes that optimize machine instructions in SSA form.
605 void TargetPassConfig::addMachineSSAOptimization() {
606 // Pre-ra tail duplication.
607 addPass(&EarlyTailDuplicateID);
609 // Optimize PHIs before DCE: removing dead PHI cycles may make more
610 // instructions dead.
611 addPass(&OptimizePHIsID, false);
613 // This pass merges large allocas. StackSlotColoring is a different pass
614 // which merges spill slots.
615 addPass(&StackColoringID, false);
617 // If the target requests it, assign local variables to stack slots relative
618 // to one another and simplify frame index references where possible.
619 addPass(&LocalStackSlotAllocationID, false);
621 // With optimization, dead code should already be eliminated. However
622 // there is one known exception: lowered code for arguments that are only
623 // used by tail calls, where the tail calls reuse the incoming stack
624 // arguments directly (see t11 in test/CodeGen/X86/sibcall.ll).
625 addPass(&DeadMachineInstructionElimID);
627 // Allow targets to insert passes that improve instruction level parallelism,
628 // like if-conversion. Such passes will typically need dominator trees and
629 // loop info, just like LICM and CSE below.
632 addPass(&MachineLICMID, false);
633 addPass(&MachineCSEID, false);
634 addPass(&MachineSinkingID);
636 addPass(&PeepholeOptimizerID, false);
637 // Clean-up the dead code that may have been generated by peephole
639 addPass(&DeadMachineInstructionElimID);
642 //===---------------------------------------------------------------------===//
643 /// Register Allocation Pass Configuration
644 //===---------------------------------------------------------------------===//
646 bool TargetPassConfig::getOptimizeRegAlloc() const {
647 switch (OptimizeRegAlloc) {
648 case cl::BOU_UNSET: return getOptLevel() != CodeGenOpt::None;
649 case cl::BOU_TRUE: return true;
650 case cl::BOU_FALSE: return false;
652 llvm_unreachable("Invalid optimize-regalloc state");
655 /// RegisterRegAlloc's global Registry tracks allocator registration.
656 MachinePassRegistry RegisterRegAlloc::Registry;
658 /// A dummy default pass factory indicates whether the register allocator is
659 /// overridden on the command line.
660 static FunctionPass *useDefaultRegisterAllocator() { return nullptr; }
661 static RegisterRegAlloc
662 defaultRegAlloc("default",
663 "pick register allocator based on -O option",
664 useDefaultRegisterAllocator);
666 /// -regalloc=... command line option.
667 static cl::opt<RegisterRegAlloc::FunctionPassCtor, false,
668 RegisterPassParser<RegisterRegAlloc> >
670 cl::init(&useDefaultRegisterAllocator),
671 cl::desc("Register allocator to use"));
674 /// Instantiate the default register allocator pass for this target for either
675 /// the optimized or unoptimized allocation path. This will be added to the pass
676 /// manager by addFastRegAlloc in the unoptimized case or addOptimizedRegAlloc
677 /// in the optimized case.
679 /// A target that uses the standard regalloc pass order for fast or optimized
680 /// allocation may still override this for per-target regalloc
681 /// selection. But -regalloc=... always takes precedence.
682 FunctionPass *TargetPassConfig::createTargetRegisterAllocator(bool Optimized) {
684 return createGreedyRegisterAllocator();
686 return createFastRegisterAllocator();
689 /// Find and instantiate the register allocation pass requested by this target
690 /// at the current optimization level. Different register allocators are
691 /// defined as separate passes because they may require different analysis.
693 /// This helper ensures that the regalloc= option is always available,
694 /// even for targets that override the default allocator.
696 /// FIXME: When MachinePassRegistry register pass IDs instead of function ptrs,
697 /// this can be folded into addPass.
698 FunctionPass *TargetPassConfig::createRegAllocPass(bool Optimized) {
699 RegisterRegAlloc::FunctionPassCtor Ctor = RegisterRegAlloc::getDefault();
701 // Initialize the global default.
704 RegisterRegAlloc::setDefault(RegAlloc);
706 if (Ctor != useDefaultRegisterAllocator)
709 // With no -regalloc= override, ask the target for a regalloc pass.
710 return createTargetRegisterAllocator(Optimized);
713 /// Return true if the default global register allocator is in use and
714 /// has not be overriden on the command line with '-regalloc=...'
715 bool TargetPassConfig::usingDefaultRegAlloc() const {
716 return RegAlloc.getNumOccurrences() == 0;
719 /// Add the minimum set of target-independent passes that are required for
720 /// register allocation. No coalescing or scheduling.
721 void TargetPassConfig::addFastRegAlloc(FunctionPass *RegAllocPass) {
722 addPass(&PHIEliminationID, false);
723 addPass(&TwoAddressInstructionPassID, false);
726 addPass(RegAllocPass);
729 /// Add standard target-independent passes that are tightly coupled with
730 /// optimized register allocation, including coalescing, machine instruction
731 /// scheduling, and register allocation itself.
732 void TargetPassConfig::addOptimizedRegAlloc(FunctionPass *RegAllocPass) {
733 addPass(&ProcessImplicitDefsID, false);
735 // LiveVariables currently requires pure SSA form.
737 // FIXME: Once TwoAddressInstruction pass no longer uses kill flags,
738 // LiveVariables can be removed completely, and LiveIntervals can be directly
739 // computed. (We still either need to regenerate kill flags after regalloc, or
740 // preferably fix the scavenger to not depend on them).
741 addPass(&LiveVariablesID, false);
743 // Edge splitting is smarter with machine loop info.
744 addPass(&MachineLoopInfoID, false);
745 addPass(&PHIEliminationID, false);
747 // Eventually, we want to run LiveIntervals before PHI elimination.
748 if (EarlyLiveIntervals)
749 addPass(&LiveIntervalsID, false);
751 addPass(&TwoAddressInstructionPassID, false);
752 addPass(&RegisterCoalescerID);
754 // PreRA instruction scheduling.
755 addPass(&MachineSchedulerID);
758 // Add the selected register allocation pass.
759 addPass(RegAllocPass);
761 // Allow targets to change the register assignments before rewriting.
764 // Finally rewrite virtual registers.
765 addPass(&VirtRegRewriterID);
767 // Perform stack slot coloring and post-ra machine LICM.
769 // FIXME: Re-enable coloring with register when it's capable of adding
771 addPass(&StackSlotColoringID);
773 // Run post-ra machine LICM to hoist reloads / remats.
775 // FIXME: can this move into MachineLateOptimization?
776 addPass(&PostRAMachineLICMID);
780 //===---------------------------------------------------------------------===//
781 /// Post RegAlloc Pass Configuration
782 //===---------------------------------------------------------------------===//
784 /// Add passes that optimize machine instructions after register allocation.
785 void TargetPassConfig::addMachineLateOptimization() {
786 // Branch folding must be run after regalloc and prolog/epilog insertion.
787 addPass(&BranchFolderPassID);
790 // Note that duplicating tail just increases code size and degrades
791 // performance for targets that require Structured Control Flow.
792 // In addition it can also make CFG irreducible. Thus we disable it.
793 if (!TM->requiresStructuredCFG())
794 addPass(&TailDuplicateID);
797 addPass(&MachineCopyPropagationID);
800 /// Add standard GC passes.
801 bool TargetPassConfig::addGCPasses() {
802 addPass(&GCMachineCodeAnalysisID, false);
806 /// Add standard basic block placement passes.
807 void TargetPassConfig::addBlockPlacement() {
808 if (addPass(&MachineBlockPlacementID, false)) {
809 // Run a separate pass to collect block placement statistics.
810 if (EnableBlockPlacementStats)
811 addPass(&MachineBlockPlacementStatsID);