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/Passes.h"
17 #include "llvm/CodeGen/GCStrategy.h"
18 #include "llvm/CodeGen/MachineFunctionPass.h"
19 #include "llvm/CodeGen/RegAllocRegistry.h"
20 #include "llvm/IR/IRPrintingPasses.h"
21 #include "llvm/IR/Verifier.h"
22 #include "llvm/MC/MCAsmInfo.h"
23 #include "llvm/PassManager.h"
24 #include "llvm/Support/CommandLine.h"
25 #include "llvm/Support/Debug.h"
26 #include "llvm/Support/ErrorHandling.h"
27 #include "llvm/Target/TargetLowering.h"
28 #include "llvm/Target/TargetSubtargetInfo.h"
29 #include "llvm/Transforms/Scalar.h"
30 #include "llvm/Transforms/Utils/SymbolRewriter.h"
34 static cl::opt<bool> DisablePostRA("disable-post-ra", cl::Hidden,
35 cl::desc("Disable Post Regalloc"));
36 static cl::opt<bool> DisableBranchFold("disable-branch-fold", cl::Hidden,
37 cl::desc("Disable branch folding"));
38 static cl::opt<bool> DisableTailDuplicate("disable-tail-duplicate", cl::Hidden,
39 cl::desc("Disable tail duplication"));
40 static cl::opt<bool> DisableEarlyTailDup("disable-early-taildup", cl::Hidden,
41 cl::desc("Disable pre-register allocation tail duplication"));
42 static cl::opt<bool> DisableBlockPlacement("disable-block-placement",
43 cl::Hidden, cl::desc("Disable probability-driven block placement"));
44 static cl::opt<bool> EnableBlockPlacementStats("enable-block-placement-stats",
45 cl::Hidden, cl::desc("Collect probability-driven block placement stats"));
46 static cl::opt<bool> DisableSSC("disable-ssc", cl::Hidden,
47 cl::desc("Disable Stack Slot Coloring"));
48 static cl::opt<bool> DisableMachineDCE("disable-machine-dce", cl::Hidden,
49 cl::desc("Disable Machine Dead Code Elimination"));
50 static cl::opt<bool> DisableEarlyIfConversion("disable-early-ifcvt", cl::Hidden,
51 cl::desc("Disable Early If-conversion"));
52 static cl::opt<bool> DisableMachineLICM("disable-machine-licm", cl::Hidden,
53 cl::desc("Disable Machine LICM"));
54 static cl::opt<bool> DisableMachineCSE("disable-machine-cse", cl::Hidden,
55 cl::desc("Disable Machine Common Subexpression Elimination"));
56 static cl::opt<cl::boolOrDefault>
57 OptimizeRegAlloc("optimize-regalloc", cl::Hidden,
58 cl::desc("Enable optimized register allocation compilation path."));
59 static cl::opt<cl::boolOrDefault>
60 EnableMachineSched("enable-misched",
61 cl::desc("Enable the machine instruction scheduling pass."));
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> PrintLSR("print-lsr-output", cl::Hidden,
78 cl::desc("Print LLVM IR produced by the loop-reduce pass"));
79 static cl::opt<bool> PrintISelInput("print-isel-input", cl::Hidden,
80 cl::desc("Print LLVM IR input to isel pass"));
81 static cl::opt<bool> PrintGCInfo("print-gc", cl::Hidden,
82 cl::desc("Dump garbage collector data"));
83 static cl::opt<bool> VerifyMachineCode("verify-machineinstrs", cl::Hidden,
84 cl::desc("Verify generated machine code"),
85 cl::init(getenv("LLVM_VERIFY_MACHINEINSTRS")!=nullptr));
86 static cl::opt<std::string>
87 PrintMachineInstrs("print-machineinstrs", cl::ValueOptional,
88 cl::desc("Print machine instrs"),
89 cl::value_desc("pass-name"), cl::init("option-unspecified"));
91 // Temporary option to allow experimenting with MachineScheduler as a post-RA
92 // scheduler. Targets can "properly" enable this with
93 // substitutePass(&PostRASchedulerID, &PostMachineSchedulerID); Ideally it
94 // wouldn't be part of the standard pass pipeline, and the target would just add
95 // a PostRA scheduling pass wherever it wants.
96 static cl::opt<bool> MISchedPostRA("misched-postra", cl::Hidden,
97 cl::desc("Run MachineScheduler post regalloc (independent of preRA sched)"));
99 // Experimental option to run live interval analysis early.
100 static cl::opt<bool> EarlyLiveIntervals("early-live-intervals", cl::Hidden,
101 cl::desc("Run live interval analysis earlier in the pipeline"));
103 static cl::opt<bool> UseCFLAA("use-cfl-aa-in-codegen",
104 cl::init(false), cl::Hidden,
105 cl::desc("Enable the new, experimental CFL alias analysis in CodeGen"));
107 /// Allow standard passes to be disabled by command line options. This supports
108 /// simple binary flags that either suppress the pass or do nothing.
109 /// i.e. -disable-mypass=false has no effect.
110 /// These should be converted to boolOrDefault in order to use applyOverride.
111 static IdentifyingPassPtr applyDisable(IdentifyingPassPtr PassID,
114 return IdentifyingPassPtr();
118 /// Allow Pass selection to be overriden by command line options. This supports
119 /// flags with ternary conditions. TargetID is passed through by default. The
120 /// pass is suppressed when the option is false. When the option is true, the
121 /// StandardID is selected if the target provides no default.
122 static IdentifyingPassPtr applyOverride(IdentifyingPassPtr TargetID,
123 cl::boolOrDefault Override,
124 AnalysisID StandardID) {
129 if (TargetID.isValid())
131 if (StandardID == nullptr)
132 report_fatal_error("Target cannot enable pass");
135 return IdentifyingPassPtr();
137 llvm_unreachable("Invalid command line option state");
140 /// Allow standard passes to be disabled by the command line, regardless of who
141 /// is adding the pass.
143 /// StandardID is the pass identified in the standard pass pipeline and provided
144 /// to addPass(). It may be a target-specific ID in the case that the target
145 /// directly adds its own pass, but in that case we harmlessly fall through.
147 /// TargetID is the pass that the target has configured to override StandardID.
149 /// StandardID may be a pseudo ID. In that case TargetID is the name of the real
150 /// pass to run. This allows multiple options to control a single pass depending
151 /// on where in the pipeline that pass is added.
152 static IdentifyingPassPtr overridePass(AnalysisID StandardID,
153 IdentifyingPassPtr TargetID) {
154 if (StandardID == &PostRASchedulerID)
155 return applyDisable(TargetID, DisablePostRA);
157 if (StandardID == &BranchFolderPassID)
158 return applyDisable(TargetID, DisableBranchFold);
160 if (StandardID == &TailDuplicateID)
161 return applyDisable(TargetID, DisableTailDuplicate);
163 if (StandardID == &TargetPassConfig::EarlyTailDuplicateID)
164 return applyDisable(TargetID, DisableEarlyTailDup);
166 if (StandardID == &MachineBlockPlacementID)
167 return applyDisable(TargetID, DisableBlockPlacement);
169 if (StandardID == &StackSlotColoringID)
170 return applyDisable(TargetID, DisableSSC);
172 if (StandardID == &DeadMachineInstructionElimID)
173 return applyDisable(TargetID, DisableMachineDCE);
175 if (StandardID == &EarlyIfConverterID)
176 return applyDisable(TargetID, DisableEarlyIfConversion);
178 if (StandardID == &MachineLICMID)
179 return applyDisable(TargetID, DisableMachineLICM);
181 if (StandardID == &MachineCSEID)
182 return applyDisable(TargetID, DisableMachineCSE);
184 if (StandardID == &MachineSchedulerID)
185 return applyOverride(TargetID, EnableMachineSched, StandardID);
187 if (StandardID == &TargetPassConfig::PostRAMachineLICMID)
188 return applyDisable(TargetID, DisablePostRAMachineLICM);
190 if (StandardID == &MachineSinkingID)
191 return applyDisable(TargetID, DisableMachineSink);
193 if (StandardID == &MachineCopyPropagationID)
194 return applyDisable(TargetID, DisableCopyProp);
199 //===---------------------------------------------------------------------===//
201 //===---------------------------------------------------------------------===//
203 INITIALIZE_PASS(TargetPassConfig, "targetpassconfig",
204 "Target Pass Configuration", false, false)
205 char TargetPassConfig::ID = 0;
208 char TargetPassConfig::EarlyTailDuplicateID = 0;
209 char TargetPassConfig::PostRAMachineLICMID = 0;
212 class PassConfigImpl {
214 // List of passes explicitly substituted by this target. Normally this is
215 // empty, but it is a convenient way to suppress or replace specific passes
216 // that are part of a standard pass pipeline without overridding the entire
217 // pipeline. This mechanism allows target options to inherit a standard pass's
218 // user interface. For example, a target may disable a standard pass by
219 // default by substituting a pass ID of zero, and the user may still enable
220 // that standard pass with an explicit command line option.
221 DenseMap<AnalysisID,IdentifyingPassPtr> TargetPasses;
223 /// Store the pairs of <AnalysisID, AnalysisID> of which the second pass
224 /// is inserted after each instance of the first one.
225 SmallVector<std::pair<AnalysisID, IdentifyingPassPtr>, 4> InsertedPasses;
229 // Out of line virtual method.
230 TargetPassConfig::~TargetPassConfig() {
234 // Out of line constructor provides default values for pass options and
235 // registers all common codegen passes.
236 TargetPassConfig::TargetPassConfig(TargetMachine *tm, PassManagerBase &pm)
237 : ImmutablePass(ID), PM(&pm), StartAfter(nullptr), StopAfter(nullptr),
238 Started(true), Stopped(false), AddingMachinePasses(false), TM(tm),
239 Impl(nullptr), Initialized(false), DisableVerify(false),
240 EnableTailMerge(true) {
242 Impl = new PassConfigImpl();
244 // Register all target independent codegen passes to activate their PassIDs,
245 // including this pass itself.
246 initializeCodeGen(*PassRegistry::getPassRegistry());
248 // Substitute Pseudo Pass IDs for real ones.
249 substitutePass(&EarlyTailDuplicateID, &TailDuplicateID);
250 substitutePass(&PostRAMachineLICMID, &MachineLICMID);
252 // Temporarily disable experimental passes.
253 const TargetSubtargetInfo &ST = TM->getSubtarget<TargetSubtargetInfo>();
254 if (!ST.useMachineScheduler())
255 disablePass(&MachineSchedulerID);
258 /// Insert InsertedPassID pass after TargetPassID.
259 void TargetPassConfig::insertPass(AnalysisID TargetPassID,
260 IdentifyingPassPtr InsertedPassID) {
261 assert(((!InsertedPassID.isInstance() &&
262 TargetPassID != InsertedPassID.getID()) ||
263 (InsertedPassID.isInstance() &&
264 TargetPassID != InsertedPassID.getInstance()->getPassID())) &&
265 "Insert a pass after itself!");
266 std::pair<AnalysisID, IdentifyingPassPtr> P(TargetPassID, InsertedPassID);
267 Impl->InsertedPasses.push_back(P);
270 /// createPassConfig - Create a pass configuration object to be used by
271 /// addPassToEmitX methods for generating a pipeline of CodeGen passes.
273 /// Targets may override this to extend TargetPassConfig.
274 TargetPassConfig *LLVMTargetMachine::createPassConfig(PassManagerBase &PM) {
275 return new TargetPassConfig(this, PM);
278 TargetPassConfig::TargetPassConfig()
279 : ImmutablePass(ID), PM(nullptr) {
280 llvm_unreachable("TargetPassConfig should not be constructed on-the-fly");
283 // Helper to verify the analysis is really immutable.
284 void TargetPassConfig::setOpt(bool &Opt, bool Val) {
285 assert(!Initialized && "PassConfig is immutable");
289 void TargetPassConfig::substitutePass(AnalysisID StandardID,
290 IdentifyingPassPtr TargetID) {
291 Impl->TargetPasses[StandardID] = TargetID;
294 IdentifyingPassPtr TargetPassConfig::getPassSubstitution(AnalysisID ID) const {
295 DenseMap<AnalysisID, IdentifyingPassPtr>::const_iterator
296 I = Impl->TargetPasses.find(ID);
297 if (I == Impl->TargetPasses.end())
302 /// Add a pass to the PassManager if that pass is supposed to be run. If the
303 /// Started/Stopped flags indicate either that the compilation should start at
304 /// a later pass or that it should stop after an earlier pass, then do not add
305 /// the pass. Finally, compare the current pass against the StartAfter
306 /// and StopAfter options and change the Started/Stopped flags accordingly.
307 void TargetPassConfig::addPass(Pass *P, bool verifyAfter, bool printAfter) {
308 assert(!Initialized && "PassConfig is immutable");
310 // Cache the Pass ID here in case the pass manager finds this pass is
311 // redundant with ones already scheduled / available, and deletes it.
312 // Fundamentally, once we add the pass to the manager, we no longer own it
313 // and shouldn't reference it.
314 AnalysisID PassID = P->getPassID();
316 if (Started && !Stopped) {
318 // Construct banner message before PM->add() as that may delete the pass.
319 if (AddingMachinePasses && (printAfter || verifyAfter))
320 Banner = std::string("After ") + std::string(P->getPassName());
322 if (AddingMachinePasses) {
324 addPrintPass(Banner);
326 addVerifyPass(Banner);
331 if (StopAfter == PassID)
333 if (StartAfter == PassID)
335 if (Stopped && !Started)
336 report_fatal_error("Cannot stop compilation after pass that is not run");
339 /// Add a CodeGen pass at this point in the pipeline after checking for target
340 /// and command line overrides.
342 /// addPass cannot return a pointer to the pass instance because is internal the
343 /// PassManager and the instance we create here may already be freed.
344 AnalysisID TargetPassConfig::addPass(AnalysisID PassID, bool verifyAfter,
346 IdentifyingPassPtr TargetID = getPassSubstitution(PassID);
347 IdentifyingPassPtr FinalPtr = overridePass(PassID, TargetID);
348 if (!FinalPtr.isValid())
352 if (FinalPtr.isInstance())
353 P = FinalPtr.getInstance();
355 P = Pass::createPass(FinalPtr.getID());
357 llvm_unreachable("Pass ID not registered");
359 AnalysisID FinalID = P->getPassID();
360 addPass(P, verifyAfter, printAfter); // Ends the lifetime of P.
362 // Add the passes after the pass P if there is any.
363 for (SmallVectorImpl<std::pair<AnalysisID, IdentifyingPassPtr> >::iterator
364 I = Impl->InsertedPasses.begin(), E = Impl->InsertedPasses.end();
366 if ((*I).first == PassID) {
367 assert((*I).second.isValid() && "Illegal Pass ID!");
369 if ((*I).second.isInstance())
370 NP = (*I).second.getInstance();
372 NP = Pass::createPass((*I).second.getID());
373 assert(NP && "Pass ID not registered");
375 addPass(NP, false, false);
381 void TargetPassConfig::printAndVerify(const std::string &Banner) {
382 addPrintPass(Banner);
383 addVerifyPass(Banner);
386 void TargetPassConfig::addPrintPass(const std::string &Banner) {
387 if (TM->shouldPrintMachineCode())
388 PM->add(createMachineFunctionPrinterPass(dbgs(), Banner));
391 void TargetPassConfig::addVerifyPass(const std::string &Banner) {
392 if (VerifyMachineCode)
393 PM->add(createMachineVerifierPass(Banner));
396 /// Add common target configurable passes that perform LLVM IR to IR transforms
397 /// following machine independent optimization.
398 void TargetPassConfig::addIRPasses() {
399 // Basic AliasAnalysis support.
400 // Add TypeBasedAliasAnalysis before BasicAliasAnalysis so that
401 // BasicAliasAnalysis wins if they disagree. This is intended to help
402 // support "obvious" type-punning idioms.
404 addPass(createCFLAliasAnalysisPass());
405 addPass(createTypeBasedAliasAnalysisPass());
406 addPass(createScopedNoAliasAAPass());
407 addPass(createBasicAliasAnalysisPass());
409 // Before running any passes, run the verifier to determine if the input
410 // coming from the front-end and/or optimizer is valid.
411 if (!DisableVerify) {
412 addPass(createVerifierPass());
413 addPass(createDebugInfoVerifierPass());
416 // Run loop strength reduction before anything else.
417 if (getOptLevel() != CodeGenOpt::None && !DisableLSR) {
418 addPass(createLoopStrengthReducePass());
420 addPass(createPrintFunctionPass(dbgs(), "\n\n*** Code after LSR ***\n"));
423 addPass(createGCLoweringPass());
425 // Make sure that no unreachable blocks are instruction selected.
426 addPass(createUnreachableBlockEliminationPass());
428 // Prepare expensive constants for SelectionDAG.
429 if (getOptLevel() != CodeGenOpt::None && !DisableConstantHoisting)
430 addPass(createConstantHoistingPass());
432 if (getOptLevel() != CodeGenOpt::None && !DisablePartialLibcallInlining)
433 addPass(createPartiallyInlineLibCallsPass());
436 /// Turn exception handling constructs into something the code generators can
438 void TargetPassConfig::addPassesToHandleExceptions() {
439 switch (TM->getMCAsmInfo()->getExceptionHandlingType()) {
440 case ExceptionHandling::SjLj:
441 // SjLj piggy-backs on dwarf for this bit. The cleanups done apply to both
442 // Dwarf EH prepare needs to be run after SjLj prepare. Otherwise,
443 // catch info can get misplaced when a selector ends up more than one block
444 // removed from the parent invoke(s). This could happen when a landing
445 // pad is shared by multiple invokes and is also a target of a normal
446 // edge from elsewhere.
447 addPass(createSjLjEHPreparePass(TM));
449 case ExceptionHandling::DwarfCFI:
450 case ExceptionHandling::ARM:
451 case ExceptionHandling::ItaniumWinEH:
452 case ExceptionHandling::MSVC: // FIXME: Needs preparation.
453 addPass(createDwarfEHPass(TM));
455 case ExceptionHandling::None:
456 addPass(createLowerInvokePass());
458 // The lower invoke pass may create unreachable code. Remove it.
459 addPass(createUnreachableBlockEliminationPass());
464 /// Add pass to prepare the LLVM IR for code generation. This should be done
465 /// before exception handling preparation passes.
466 void TargetPassConfig::addCodeGenPrepare() {
467 if (getOptLevel() != CodeGenOpt::None && !DisableCGP)
468 addPass(createCodeGenPreparePass(TM));
469 addPass(createRewriteSymbolsPass());
472 /// Add common passes that perform LLVM IR to IR transforms in preparation for
473 /// instruction selection.
474 void TargetPassConfig::addISelPrepare() {
477 // Need to verify DebugInfo *before* creating the stack protector analysis.
478 // It's a function pass, and verifying between it and its users causes a
481 addPass(createDebugInfoVerifierPass());
483 addPass(createStackProtectorPass(TM));
486 addPass(createPrintFunctionPass(
487 dbgs(), "\n\n*** Final LLVM Code input to ISel ***\n"));
489 // All passes which modify the LLVM IR are now complete; run the verifier
490 // to ensure that the IR is valid.
492 addPass(createVerifierPass());
495 /// Add the complete set of target-independent postISel code generator passes.
497 /// This can be read as the standard order of major LLVM CodeGen stages. Stages
498 /// with nontrivial configuration or multiple passes are broken out below in
499 /// add%Stage routines.
501 /// Any TargetPassConfig::addXX routine may be overriden by the Target. The
502 /// addPre/Post methods with empty header implementations allow injecting
503 /// target-specific fixups just before or after major stages. Additionally,
504 /// targets have the flexibility to change pass order within a stage by
505 /// overriding default implementation of add%Stage routines below. Each
506 /// technique has maintainability tradeoffs because alternate pass orders are
507 /// not well supported. addPre/Post works better if the target pass is easily
508 /// tied to a common pass. But if it has subtle dependencies on multiple passes,
509 /// the target should override the stage instead.
511 /// TODO: We could use a single addPre/Post(ID) hook to allow pass injection
512 /// before/after any target-independent pass. But it's currently overkill.
513 void TargetPassConfig::addMachinePasses() {
514 AddingMachinePasses = true;
516 // Insert a machine instr printer pass after the specified pass.
517 // If -print-machineinstrs specified, print machineinstrs after all passes.
518 if (StringRef(PrintMachineInstrs.getValue()).equals(""))
519 TM->Options.PrintMachineCode = true;
520 else if (!StringRef(PrintMachineInstrs.getValue())
521 .equals("option-unspecified")) {
522 const PassRegistry *PR = PassRegistry::getPassRegistry();
523 const PassInfo *TPI = PR->getPassInfo(PrintMachineInstrs.getValue());
524 const PassInfo *IPI = PR->getPassInfo(StringRef("machineinstr-printer"));
525 assert (TPI && IPI && "Pass ID not registered!");
526 const char *TID = (const char *)(TPI->getTypeInfo());
527 const char *IID = (const char *)(IPI->getTypeInfo());
528 insertPass(TID, IID);
531 // Print the instruction selected machine code...
532 printAndVerify("After Instruction Selection");
534 // Expand pseudo-instructions emitted by ISel.
535 addPass(&ExpandISelPseudosID);
537 // Add passes that optimize machine instructions in SSA form.
538 if (getOptLevel() != CodeGenOpt::None) {
539 addMachineSSAOptimization();
541 // If the target requests it, assign local variables to stack slots relative
542 // to one another and simplify frame index references where possible.
543 addPass(&LocalStackSlotAllocationID, false);
546 // Run pre-ra passes.
549 // Run register allocation and passes that are tightly coupled with it,
550 // including phi elimination and scheduling.
551 if (getOptimizeRegAlloc())
552 addOptimizedRegAlloc(createRegAllocPass(true));
554 addFastRegAlloc(createRegAllocPass(false));
556 // Run post-ra passes.
559 // Insert prolog/epilog code. Eliminate abstract frame index references...
560 addPass(&PrologEpilogCodeInserterID);
562 /// Add passes that optimize machine instructions after register allocation.
563 if (getOptLevel() != CodeGenOpt::None)
564 addMachineLateOptimization();
566 // Expand pseudo instructions before second scheduling pass.
567 addPass(&ExpandPostRAPseudosID);
569 // Run pre-sched2 passes.
572 // Second pass scheduler.
573 if (getOptLevel() != CodeGenOpt::None) {
575 addPass(&PostMachineSchedulerID);
577 addPass(&PostRASchedulerID);
583 addPass(createGCInfoPrinter(dbgs()), false, false);
586 // Basic block placement.
587 if (getOptLevel() != CodeGenOpt::None)
592 addPass(&StackMapLivenessID, false);
594 AddingMachinePasses = false;
597 /// Add passes that optimize machine instructions in SSA form.
598 void TargetPassConfig::addMachineSSAOptimization() {
599 // Pre-ra tail duplication.
600 addPass(&EarlyTailDuplicateID);
602 // Optimize PHIs before DCE: removing dead PHI cycles may make more
603 // instructions dead.
604 addPass(&OptimizePHIsID, false);
606 // This pass merges large allocas. StackSlotColoring is a different pass
607 // which merges spill slots.
608 addPass(&StackColoringID, false);
610 // If the target requests it, assign local variables to stack slots relative
611 // to one another and simplify frame index references where possible.
612 addPass(&LocalStackSlotAllocationID, false);
614 // With optimization, dead code should already be eliminated. However
615 // there is one known exception: lowered code for arguments that are only
616 // used by tail calls, where the tail calls reuse the incoming stack
617 // arguments directly (see t11 in test/CodeGen/X86/sibcall.ll).
618 addPass(&DeadMachineInstructionElimID);
620 // Allow targets to insert passes that improve instruction level parallelism,
621 // like if-conversion. Such passes will typically need dominator trees and
622 // loop info, just like LICM and CSE below.
625 addPass(&MachineLICMID, false);
626 addPass(&MachineCSEID, false);
627 addPass(&MachineSinkingID);
629 addPass(&PeepholeOptimizerID, false);
630 // Clean-up the dead code that may have been generated by peephole
632 addPass(&DeadMachineInstructionElimID);
635 //===---------------------------------------------------------------------===//
636 /// Register Allocation Pass Configuration
637 //===---------------------------------------------------------------------===//
639 bool TargetPassConfig::getOptimizeRegAlloc() const {
640 switch (OptimizeRegAlloc) {
641 case cl::BOU_UNSET: return getOptLevel() != CodeGenOpt::None;
642 case cl::BOU_TRUE: return true;
643 case cl::BOU_FALSE: return false;
645 llvm_unreachable("Invalid optimize-regalloc state");
648 /// RegisterRegAlloc's global Registry tracks allocator registration.
649 MachinePassRegistry RegisterRegAlloc::Registry;
651 /// A dummy default pass factory indicates whether the register allocator is
652 /// overridden on the command line.
653 static FunctionPass *useDefaultRegisterAllocator() { return nullptr; }
654 static RegisterRegAlloc
655 defaultRegAlloc("default",
656 "pick register allocator based on -O option",
657 useDefaultRegisterAllocator);
659 /// -regalloc=... command line option.
660 static cl::opt<RegisterRegAlloc::FunctionPassCtor, false,
661 RegisterPassParser<RegisterRegAlloc> >
663 cl::init(&useDefaultRegisterAllocator),
664 cl::desc("Register allocator to use"));
667 /// Instantiate the default register allocator pass for this target for either
668 /// the optimized or unoptimized allocation path. This will be added to the pass
669 /// manager by addFastRegAlloc in the unoptimized case or addOptimizedRegAlloc
670 /// in the optimized case.
672 /// A target that uses the standard regalloc pass order for fast or optimized
673 /// allocation may still override this for per-target regalloc
674 /// selection. But -regalloc=... always takes precedence.
675 FunctionPass *TargetPassConfig::createTargetRegisterAllocator(bool Optimized) {
677 return createGreedyRegisterAllocator();
679 return createFastRegisterAllocator();
682 /// Find and instantiate the register allocation pass requested by this target
683 /// at the current optimization level. Different register allocators are
684 /// defined as separate passes because they may require different analysis.
686 /// This helper ensures that the regalloc= option is always available,
687 /// even for targets that override the default allocator.
689 /// FIXME: When MachinePassRegistry register pass IDs instead of function ptrs,
690 /// this can be folded into addPass.
691 FunctionPass *TargetPassConfig::createRegAllocPass(bool Optimized) {
692 RegisterRegAlloc::FunctionPassCtor Ctor = RegisterRegAlloc::getDefault();
694 // Initialize the global default.
697 RegisterRegAlloc::setDefault(RegAlloc);
699 if (Ctor != useDefaultRegisterAllocator)
702 // With no -regalloc= override, ask the target for a regalloc pass.
703 return createTargetRegisterAllocator(Optimized);
706 /// Return true if the default global register allocator is in use and
707 /// has not be overriden on the command line with '-regalloc=...'
708 bool TargetPassConfig::usingDefaultRegAlloc() const {
709 return RegAlloc.getNumOccurrences() == 0;
712 /// Add the minimum set of target-independent passes that are required for
713 /// register allocation. No coalescing or scheduling.
714 void TargetPassConfig::addFastRegAlloc(FunctionPass *RegAllocPass) {
715 addPass(&PHIEliminationID, false);
716 addPass(&TwoAddressInstructionPassID, false);
718 addPass(RegAllocPass);
721 /// Add standard target-independent passes that are tightly coupled with
722 /// optimized register allocation, including coalescing, machine instruction
723 /// scheduling, and register allocation itself.
724 void TargetPassConfig::addOptimizedRegAlloc(FunctionPass *RegAllocPass) {
725 addPass(&ProcessImplicitDefsID, false);
727 // LiveVariables currently requires pure SSA form.
729 // FIXME: Once TwoAddressInstruction pass no longer uses kill flags,
730 // LiveVariables can be removed completely, and LiveIntervals can be directly
731 // computed. (We still either need to regenerate kill flags after regalloc, or
732 // preferably fix the scavenger to not depend on them).
733 addPass(&LiveVariablesID, false);
735 // Edge splitting is smarter with machine loop info.
736 addPass(&MachineLoopInfoID, false);
737 addPass(&PHIEliminationID, false);
739 // Eventually, we want to run LiveIntervals before PHI elimination.
740 if (EarlyLiveIntervals)
741 addPass(&LiveIntervalsID, false);
743 addPass(&TwoAddressInstructionPassID, false);
744 addPass(&RegisterCoalescerID);
746 // PreRA instruction scheduling.
747 addPass(&MachineSchedulerID);
749 // Add the selected register allocation pass.
750 addPass(RegAllocPass);
752 // Allow targets to change the register assignments before rewriting.
755 // Finally rewrite virtual registers.
756 addPass(&VirtRegRewriterID);
758 // Perform stack slot coloring and post-ra machine LICM.
760 // FIXME: Re-enable coloring with register when it's capable of adding
762 addPass(&StackSlotColoringID);
764 // Run post-ra machine LICM to hoist reloads / remats.
766 // FIXME: can this move into MachineLateOptimization?
767 addPass(&PostRAMachineLICMID);
770 //===---------------------------------------------------------------------===//
771 /// Post RegAlloc Pass Configuration
772 //===---------------------------------------------------------------------===//
774 /// Add passes that optimize machine instructions after register allocation.
775 void TargetPassConfig::addMachineLateOptimization() {
776 // Branch folding must be run after regalloc and prolog/epilog insertion.
777 addPass(&BranchFolderPassID);
780 // Note that duplicating tail just increases code size and degrades
781 // performance for targets that require Structured Control Flow.
782 // In addition it can also make CFG irreducible. Thus we disable it.
783 if (!TM->requiresStructuredCFG())
784 addPass(&TailDuplicateID);
787 addPass(&MachineCopyPropagationID);
790 /// Add standard GC passes.
791 bool TargetPassConfig::addGCPasses() {
792 addPass(&GCMachineCodeAnalysisID, false);
796 /// Add standard basic block placement passes.
797 void TargetPassConfig::addBlockPlacement() {
798 if (addPass(&MachineBlockPlacementID, false)) {
799 // Run a separate pass to collect block placement statistics.
800 if (EnableBlockPlacementStats)
801 addPass(&MachineBlockPlacementStatsID);