1 //===- ReducerWorkItem.cpp - Wrapper for Module and MachineFunction -------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "ReducerWorkItem.h"
10 #include "llvm/CodeGen/CommandFlags.h"
11 #include "llvm/CodeGen/MIRParser/MIRParser.h"
12 #include "llvm/CodeGen/MIRPrinter.h"
13 #include "llvm/CodeGen/MachineDominators.h"
14 #include "llvm/CodeGen/MachineFrameInfo.h"
15 #include "llvm/CodeGen/MachineFunction.h"
16 #include "llvm/CodeGen/MachineFunctionPass.h"
17 #include "llvm/CodeGen/MachineModuleInfo.h"
18 #include "llvm/CodeGen/MachineRegisterInfo.h"
19 #include "llvm/CodeGen/TargetInstrInfo.h"
20 #include "llvm/IR/Verifier.h"
21 #include "llvm/IRReader/IRReader.h"
22 #include "llvm/MC/TargetRegistry.h"
23 #include "llvm/Support/Host.h"
24 #include "llvm/Support/SourceMgr.h"
25 #include "llvm/Support/WithColor.h"
26 #include "llvm/Target/TargetMachine.h"
27 #include "llvm/Transforms/Utils/Cloning.h"
28 
29 extern cl::OptionCategory LLVMReduceOptions;
30 static cl::opt<std::string> TargetTriple("mtriple",
31                                          cl::desc("Set the target triple"),
32                                          cl::cat(LLVMReduceOptions));
33 
34 static void cloneFrameInfo(
35     MachineFrameInfo &DstMFI, const MachineFrameInfo &SrcMFI,
36     const DenseMap<MachineBasicBlock *, MachineBasicBlock *> &Src2DstMBB) {
37   DstMFI.setFrameAddressIsTaken(SrcMFI.isFrameAddressTaken());
38   DstMFI.setReturnAddressIsTaken(SrcMFI.isReturnAddressTaken());
39   DstMFI.setHasStackMap(SrcMFI.hasStackMap());
40   DstMFI.setHasPatchPoint(SrcMFI.hasPatchPoint());
41   DstMFI.setUseLocalStackAllocationBlock(
42       SrcMFI.getUseLocalStackAllocationBlock());
43   DstMFI.setOffsetAdjustment(SrcMFI.getOffsetAdjustment());
44 
45   DstMFI.ensureMaxAlignment(SrcMFI.getMaxAlign());
46   assert(DstMFI.getMaxAlign() == SrcMFI.getMaxAlign() &&
47          "we need to set exact alignment");
48 
49   DstMFI.setAdjustsStack(SrcMFI.adjustsStack());
50   DstMFI.setHasCalls(SrcMFI.hasCalls());
51   DstMFI.setHasOpaqueSPAdjustment(SrcMFI.hasOpaqueSPAdjustment());
52   DstMFI.setHasCopyImplyingStackAdjustment(
53       SrcMFI.hasCopyImplyingStackAdjustment());
54   DstMFI.setHasVAStart(SrcMFI.hasVAStart());
55   DstMFI.setHasMustTailInVarArgFunc(SrcMFI.hasMustTailInVarArgFunc());
56   DstMFI.setHasTailCall(SrcMFI.hasTailCall());
57 
58   if (SrcMFI.isMaxCallFrameSizeComputed())
59     DstMFI.setMaxCallFrameSize(SrcMFI.getMaxCallFrameSize());
60 
61   DstMFI.setCVBytesOfCalleeSavedRegisters(
62       SrcMFI.getCVBytesOfCalleeSavedRegisters());
63 
64   if (MachineBasicBlock *SavePt = SrcMFI.getSavePoint())
65     DstMFI.setSavePoint(Src2DstMBB.find(SavePt)->second);
66   if (MachineBasicBlock *RestorePt = SrcMFI.getRestorePoint())
67     DstMFI.setRestorePoint(Src2DstMBB.find(RestorePt)->second);
68 
69 
70   auto CopyObjectProperties = [](MachineFrameInfo &DstMFI,
71                                  const MachineFrameInfo &SrcMFI, int FI) {
72     if (SrcMFI.isStatepointSpillSlotObjectIndex(FI))
73       DstMFI.markAsStatepointSpillSlotObjectIndex(FI);
74     DstMFI.setObjectSSPLayout(FI, SrcMFI.getObjectSSPLayout(FI));
75     DstMFI.setObjectZExt(FI, SrcMFI.isObjectZExt(FI));
76     DstMFI.setObjectSExt(FI, SrcMFI.isObjectSExt(FI));
77   };
78 
79   for (int i = 0, e = SrcMFI.getNumObjects() - SrcMFI.getNumFixedObjects();
80        i != e; ++i) {
81     int NewFI;
82 
83     assert(!SrcMFI.isFixedObjectIndex(i));
84     if (SrcMFI.isVariableSizedObjectIndex(i)) {
85       NewFI = DstMFI.CreateVariableSizedObject(SrcMFI.getObjectAlign(i),
86                                                SrcMFI.getObjectAllocation(i));
87     } else {
88       NewFI = DstMFI.CreateStackObject(
89           SrcMFI.getObjectSize(i), SrcMFI.getObjectAlign(i),
90           SrcMFI.isSpillSlotObjectIndex(i), SrcMFI.getObjectAllocation(i),
91           SrcMFI.getStackID(i));
92       DstMFI.setObjectOffset(NewFI, SrcMFI.getObjectOffset(i));
93     }
94 
95     CopyObjectProperties(DstMFI, SrcMFI, i);
96 
97     (void)NewFI;
98     assert(i == NewFI && "expected to keep stable frame index numbering");
99   }
100 
101   // Copy the fixed frame objects backwards to preserve frame index numbers,
102   // since CreateFixedObject uses front insertion.
103   for (int i = -1; i >= (int)-SrcMFI.getNumFixedObjects(); --i) {
104     assert(SrcMFI.isFixedObjectIndex(i));
105     int NewFI = DstMFI.CreateFixedObject(
106       SrcMFI.getObjectSize(i), SrcMFI.getObjectOffset(i),
107       SrcMFI.isImmutableObjectIndex(i), SrcMFI.isAliasedObjectIndex(i));
108     CopyObjectProperties(DstMFI, SrcMFI, i);
109 
110     (void)NewFI;
111     assert(i == NewFI && "expected to keep stable frame index numbering");
112   }
113 
114   for (unsigned I = 0, E = SrcMFI.getLocalFrameObjectCount(); I < E; ++I) {
115     auto LocalObject = SrcMFI.getLocalFrameObjectMap(I);
116     DstMFI.mapLocalFrameObject(LocalObject.first, LocalObject.second);
117   }
118 
119   DstMFI.setCalleeSavedInfo(SrcMFI.getCalleeSavedInfo());
120 
121   if (SrcMFI.hasStackProtectorIndex()) {
122     DstMFI.setStackProtectorIndex(SrcMFI.getStackProtectorIndex());
123   }
124 
125   // FIXME: Needs test, missing MIR serialization.
126   if (SrcMFI.hasFunctionContextIndex()) {
127     DstMFI.setFunctionContextIndex(SrcMFI.getFunctionContextIndex());
128   }
129 }
130 
131 static void cloneMemOperands(MachineInstr &DstMI, MachineInstr &SrcMI,
132                              MachineFunction &SrcMF, MachineFunction &DstMF) {
133   // The new MachineMemOperands should be owned by the new function's
134   // Allocator.
135   PseudoSourceValueManager &PSVMgr = DstMF.getPSVManager();
136 
137   // We also need to remap the PseudoSourceValues from the new function's
138   // PseudoSourceValueManager.
139   SmallVector<MachineMemOperand *, 2> NewMMOs;
140   for (MachineMemOperand *OldMMO : SrcMI.memoperands()) {
141     MachinePointerInfo NewPtrInfo(OldMMO->getPointerInfo());
142     if (const PseudoSourceValue *PSV =
143             NewPtrInfo.V.dyn_cast<const PseudoSourceValue *>()) {
144       switch (PSV->kind()) {
145       case PseudoSourceValue::Stack:
146         NewPtrInfo.V = PSVMgr.getStack();
147         break;
148       case PseudoSourceValue::GOT:
149         NewPtrInfo.V = PSVMgr.getGOT();
150         break;
151       case PseudoSourceValue::JumpTable:
152         NewPtrInfo.V = PSVMgr.getJumpTable();
153         break;
154       case PseudoSourceValue::ConstantPool:
155         NewPtrInfo.V = PSVMgr.getConstantPool();
156         break;
157       case PseudoSourceValue::FixedStack:
158         NewPtrInfo.V = PSVMgr.getFixedStack(
159             cast<FixedStackPseudoSourceValue>(PSV)->getFrameIndex());
160         break;
161       case PseudoSourceValue::GlobalValueCallEntry:
162         NewPtrInfo.V = PSVMgr.getGlobalValueCallEntry(
163             cast<GlobalValuePseudoSourceValue>(PSV)->getValue());
164         break;
165       case PseudoSourceValue::ExternalSymbolCallEntry:
166         NewPtrInfo.V = PSVMgr.getExternalSymbolCallEntry(
167             cast<ExternalSymbolPseudoSourceValue>(PSV)->getSymbol());
168         break;
169       case PseudoSourceValue::TargetCustom:
170       default:
171         // FIXME: We have no generic interface for allocating custom PSVs.
172         report_fatal_error("Cloning TargetCustom PSV not handled");
173       }
174     }
175 
176     MachineMemOperand *NewMMO = DstMF.getMachineMemOperand(
177         NewPtrInfo, OldMMO->getFlags(), OldMMO->getMemoryType(),
178         OldMMO->getBaseAlign(), OldMMO->getAAInfo(), OldMMO->getRanges(),
179         OldMMO->getSyncScopeID(), OldMMO->getSuccessOrdering(),
180         OldMMO->getFailureOrdering());
181     NewMMOs.push_back(NewMMO);
182   }
183 
184   DstMI.setMemRefs(DstMF, NewMMOs);
185 }
186 
187 static std::unique_ptr<MachineFunction> cloneMF(MachineFunction *SrcMF,
188                                                 MachineModuleInfo &DestMMI) {
189   auto DstMF = std::make_unique<MachineFunction>(
190       SrcMF->getFunction(), SrcMF->getTarget(), SrcMF->getSubtarget(),
191       SrcMF->getFunctionNumber(), DestMMI);
192   DenseMap<MachineBasicBlock *, MachineBasicBlock *> Src2DstMBB;
193 
194   auto *SrcMRI = &SrcMF->getRegInfo();
195   auto *DstMRI = &DstMF->getRegInfo();
196 
197   // Clone blocks.
198   for (MachineBasicBlock &SrcMBB : *SrcMF) {
199     MachineBasicBlock *DstMBB =
200         DstMF->CreateMachineBasicBlock(SrcMBB.getBasicBlock());
201     Src2DstMBB[&SrcMBB] = DstMBB;
202 
203     if (SrcMBB.hasAddressTaken())
204       DstMBB->setHasAddressTaken();
205 
206     // FIXME: This is not serialized
207     if (SrcMBB.hasLabelMustBeEmitted())
208       DstMBB->setLabelMustBeEmitted();
209 
210     DstMBB->setAlignment(SrcMBB.getAlignment());
211 
212     // FIXME: This is not serialized
213     DstMBB->setMaxBytesForAlignment(SrcMBB.getMaxBytesForAlignment());
214 
215     DstMBB->setIsEHPad(SrcMBB.isEHPad());
216     DstMBB->setIsEHScopeEntry(SrcMBB.isEHScopeEntry());
217     DstMBB->setIsEHCatchretTarget(SrcMBB.isEHCatchretTarget());
218     DstMBB->setIsEHFuncletEntry(SrcMBB.isEHFuncletEntry());
219 
220     // FIXME: These are not serialized
221     DstMBB->setIsCleanupFuncletEntry(SrcMBB.isCleanupFuncletEntry());
222     DstMBB->setIsBeginSection(SrcMBB.isBeginSection());
223     DstMBB->setIsEndSection(SrcMBB.isEndSection());
224 
225     DstMBB->setSectionID(SrcMBB.getSectionID());
226     DstMBB->setIsInlineAsmBrIndirectTarget(
227         SrcMBB.isInlineAsmBrIndirectTarget());
228 
229     // FIXME: This is not serialized
230     if (Optional<uint64_t> Weight = SrcMBB.getIrrLoopHeaderWeight())
231       DstMBB->setIrrLoopHeaderWeight(*Weight);
232   }
233 
234   const MachineFrameInfo &SrcMFI = SrcMF->getFrameInfo();
235   MachineFrameInfo &DstMFI = DstMF->getFrameInfo();
236 
237   // Copy stack objects and other info
238   cloneFrameInfo(DstMFI, SrcMFI, Src2DstMBB);
239 
240   // Remap the debug info frame index references.
241   DstMF->VariableDbgInfos = SrcMF->VariableDbgInfos;
242 
243   // Clone virtual registers
244   for (unsigned I = 0, E = SrcMRI->getNumVirtRegs(); I != E; ++I) {
245     Register Reg = Register::index2VirtReg(I);
246     Register NewReg = DstMRI->createIncompleteVirtualRegister(
247       SrcMRI->getVRegName(Reg));
248     assert(NewReg == Reg && "expected to preserve virtreg number");
249 
250     DstMRI->setRegClassOrRegBank(NewReg, SrcMRI->getRegClassOrRegBank(Reg));
251 
252     LLT RegTy = SrcMRI->getType(Reg);
253     if (RegTy.isValid())
254       DstMRI->setType(NewReg, RegTy);
255 
256     // Copy register allocation hints.
257     const auto &Hints = SrcMRI->getRegAllocationHints(Reg);
258     for (Register PrefReg : Hints.second)
259       DstMRI->addRegAllocationHint(NewReg, PrefReg);
260   }
261 
262   const TargetSubtargetInfo &STI = DstMF->getSubtarget();
263   const TargetInstrInfo *TII = STI.getInstrInfo();
264   const TargetRegisterInfo *TRI = STI.getRegisterInfo();
265 
266   // Link blocks.
267   for (auto &SrcMBB : *SrcMF) {
268     auto *DstMBB = Src2DstMBB[&SrcMBB];
269     DstMF->push_back(DstMBB);
270 
271     for (auto It = SrcMBB.succ_begin(), IterEnd = SrcMBB.succ_end();
272          It != IterEnd; ++It) {
273       auto *SrcSuccMBB = *It;
274       auto *DstSuccMBB = Src2DstMBB[SrcSuccMBB];
275       DstMBB->addSuccessor(DstSuccMBB, SrcMBB.getSuccProbability(It));
276     }
277 
278     for (auto &LI : SrcMBB.liveins_dbg())
279       DstMBB->addLiveIn(LI);
280 
281     // Make sure MRI knows about registers clobbered by unwinder.
282     if (DstMBB->isEHPad()) {
283       if (auto *RegMask = TRI->getCustomEHPadPreservedMask(*DstMF))
284         DstMRI->addPhysRegsUsedFromRegMask(RegMask);
285     }
286   }
287 
288   // Clone instructions.
289   for (auto &SrcMBB : *SrcMF) {
290     auto *DstMBB = Src2DstMBB[&SrcMBB];
291     for (auto &SrcMI : SrcMBB) {
292       const auto &MCID = TII->get(SrcMI.getOpcode());
293       auto *DstMI = DstMF->CreateMachineInstr(MCID, SrcMI.getDebugLoc(),
294                                               /*NoImplicit=*/true);
295       DstMI->setFlags(SrcMI.getFlags());
296       DstMI->setAsmPrinterFlag(SrcMI.getAsmPrinterFlags());
297 
298       DstMBB->push_back(DstMI);
299       for (auto &SrcMO : SrcMI.operands()) {
300         MachineOperand DstMO(SrcMO);
301         DstMO.clearParent();
302 
303         // Update MBB.
304         if (DstMO.isMBB())
305           DstMO.setMBB(Src2DstMBB[DstMO.getMBB()]);
306         else if (DstMO.isRegMask())
307           DstMRI->addPhysRegsUsedFromRegMask(DstMO.getRegMask());
308 
309         DstMI->addOperand(DstMO);
310       }
311 
312       cloneMemOperands(*DstMI, SrcMI, *SrcMF, *DstMF);
313     }
314   }
315 
316   DstMF->setAlignment(SrcMF->getAlignment());
317   DstMF->setExposesReturnsTwice(SrcMF->exposesReturnsTwice());
318   DstMF->setHasInlineAsm(SrcMF->hasInlineAsm());
319   DstMF->setHasWinCFI(SrcMF->hasWinCFI());
320 
321   DstMF->getProperties().reset().set(SrcMF->getProperties());
322 
323   if (!SrcMF->getFrameInstructions().empty() ||
324       !SrcMF->getLongjmpTargets().empty() ||
325       !SrcMF->getCatchretTargets().empty())
326     report_fatal_error("cloning not implemented for machine function property");
327 
328   DstMF->setCallsEHReturn(SrcMF->callsEHReturn());
329   DstMF->setCallsUnwindInit(SrcMF->callsUnwindInit());
330   DstMF->setHasEHCatchret(SrcMF->hasEHCatchret());
331   DstMF->setHasEHScopes(SrcMF->hasEHScopes());
332   DstMF->setHasEHFunclets(SrcMF->hasEHFunclets());
333 
334   if (!SrcMF->getLandingPads().empty() ||
335       !SrcMF->getCodeViewAnnotations().empty() ||
336       !SrcMF->getTypeInfos().empty() ||
337       !SrcMF->getFilterIds().empty() ||
338       SrcMF->hasAnyWasmLandingPadIndex() ||
339       SrcMF->hasAnyCallSiteLandingPad() ||
340       SrcMF->hasAnyCallSiteLabel() ||
341       !SrcMF->getCallSitesInfo().empty())
342     report_fatal_error("cloning not implemented for machine function property");
343 
344   DstMF->setDebugInstrNumberingCount(SrcMF->DebugInstrNumberingCount);
345 
346   if (!DstMF->cloneInfoFrom(*SrcMF, Src2DstMBB))
347     report_fatal_error("target does not implement MachineFunctionInfo cloning");
348 
349   DstMRI->freezeReservedRegs(*DstMF);
350 
351   DstMF->verify(nullptr, "", /*AbortOnError=*/true);
352   return DstMF;
353 }
354 
355 std::unique_ptr<ReducerWorkItem>
356 parseReducerWorkItem(const char *ToolName, StringRef Filename,
357                      LLVMContext &Ctxt, std::unique_ptr<TargetMachine> &TM,
358                      bool IsMIR) {
359   Triple TheTriple;
360 
361   auto MMM = std::make_unique<ReducerWorkItem>();
362 
363   if (IsMIR) {
364     auto FileOrErr = MemoryBuffer::getFileOrSTDIN(Filename, /*IsText=*/true);
365     if (std::error_code EC = FileOrErr.getError()) {
366       WithColor::error(errs(), ToolName) << EC.message() << '\n';
367       return nullptr;
368     }
369 
370     std::unique_ptr<MIRParser> MParser =
371         createMIRParser(std::move(FileOrErr.get()), Ctxt);
372 
373     auto SetDataLayout =
374         [&](StringRef DataLayoutTargetTriple) -> Optional<std::string> {
375       // If we are supposed to override the target triple, do so now.
376       std::string IRTargetTriple = DataLayoutTargetTriple.str();
377       if (!TargetTriple.empty())
378         IRTargetTriple = Triple::normalize(TargetTriple);
379       TheTriple = Triple(IRTargetTriple);
380       if (TheTriple.getTriple().empty())
381         TheTriple.setTriple(sys::getDefaultTargetTriple());
382 
383       std::string Error;
384       const Target *TheTarget =
385           TargetRegistry::lookupTarget(codegen::getMArch(), TheTriple, Error);
386       if (!TheTarget) {
387         WithColor::error(errs(), ToolName) << Error;
388         exit(1);
389       }
390 
391       // Hopefully the MIR parsing doesn't depend on any options.
392       TargetOptions Options;
393       Optional<Reloc::Model> RM = codegen::getExplicitRelocModel();
394       std::string CPUStr = codegen::getCPUStr();
395       std::string FeaturesStr = codegen::getFeaturesStr();
396       TM = std::unique_ptr<TargetMachine>(TheTarget->createTargetMachine(
397           TheTriple.getTriple(), CPUStr, FeaturesStr, Options, RM,
398           codegen::getExplicitCodeModel(), CodeGenOpt::Default));
399       assert(TM && "Could not allocate target machine!");
400 
401       return TM->createDataLayout().getStringRepresentation();
402     };
403 
404     std::unique_ptr<Module> M = MParser->parseIRModule(SetDataLayout);
405     LLVMTargetMachine *LLVMTM = static_cast<LLVMTargetMachine *>(TM.get());
406 
407     MMM->MMI = std::make_unique<MachineModuleInfo>(LLVMTM);
408     MParser->parseMachineFunctions(*M, *MMM->MMI);
409     MMM->M = std::move(M);
410   } else {
411     SMDiagnostic Err;
412     std::unique_ptr<Module> Result = parseIRFile(Filename, Err, Ctxt);
413     if (!Result) {
414       Err.print(ToolName, errs());
415       return std::unique_ptr<ReducerWorkItem>();
416     }
417     MMM->M = std::move(Result);
418   }
419   if (verifyReducerWorkItem(*MMM, &errs())) {
420     WithColor::error(errs(), ToolName)
421         << Filename << " - input module is broken!\n";
422     return std::unique_ptr<ReducerWorkItem>();
423   }
424   return MMM;
425 }
426 
427 std::unique_ptr<ReducerWorkItem>
428 cloneReducerWorkItem(const ReducerWorkItem &MMM, const TargetMachine *TM) {
429   auto CloneMMM = std::make_unique<ReducerWorkItem>();
430   if (TM) {
431     // We're assuming the Module IR contents are always unchanged by MIR
432     // reductions, and can share it as a constant.
433     CloneMMM->M = MMM.M;
434 
435     // MachineModuleInfo contains a lot of other state used during codegen which
436     // we won't be using here, but we should be able to ignore it (although this
437     // is pretty ugly).
438     const LLVMTargetMachine *LLVMTM =
439         static_cast<const LLVMTargetMachine *>(TM);
440     CloneMMM->MMI = std::make_unique<MachineModuleInfo>(LLVMTM);
441 
442     for (const Function &F : MMM.getModule()) {
443       if (auto *MF = MMM.MMI->getMachineFunction(F))
444         CloneMMM->MMI->insertFunction(F, cloneMF(MF, *CloneMMM->MMI));
445     }
446   } else {
447     CloneMMM->M = CloneModule(*MMM.M);
448   }
449   return CloneMMM;
450 }
451 
452 bool verifyReducerWorkItem(const ReducerWorkItem &MMM, raw_fd_ostream *OS) {
453   if (verifyModule(*MMM.M, OS))
454     return true;
455 
456   if (!MMM.MMI)
457     return false;
458 
459   for (const Function &F : MMM.getModule()) {
460     if (const MachineFunction *MF = MMM.MMI->getMachineFunction(F)) {
461       if (!MF->verify(nullptr, "", /*AbortOnError=*/false))
462         return true;
463     }
464   }
465 
466   return false;
467 }
468 
469 void ReducerWorkItem::print(raw_ostream &ROS, void *p) const {
470   if (MMI) {
471     printMIR(ROS, *M);
472     for (Function &F : *M) {
473       if (auto *MF = MMI->getMachineFunction(F))
474         printMIR(ROS, *MF);
475     }
476   } else {
477     M->print(ROS, /*AssemblyAnnotationWriter=*/nullptr,
478              /*ShouldPreserveUseListOrder=*/true);
479   }
480 }
481 
482 // FIXME: We might want to use a different metric than "number of
483 // bytes in serialized IR" to detect non-progress of the main delta
484 // loop
485 uint64_t ReducerWorkItem::getIRSize() const {
486   std::string Str;
487   raw_string_ostream SS(Str);
488   print(SS, /*AnnotationWriter=*/nullptr);
489   return Str.length();
490 }
491 
492 /// Try to produce some number that indicates a function is getting smaller /
493 /// simpler.
494 static uint64_t computeMIRComplexityScoreImpl(const MachineFunction &MF) {
495   uint64_t Score = 0;
496   const MachineFrameInfo &MFI = MF.getFrameInfo();
497 
498   // Add for stack objects
499   Score += MFI.getNumObjects();
500 
501   // Add in the block count.
502   Score += 2 * MF.size();
503 
504   const MachineRegisterInfo &MRI = MF.getRegInfo();
505   for (unsigned I = 0, E = MRI.getNumVirtRegs(); I != E; ++I) {
506     Register Reg = Register::index2VirtReg(I);
507     Score += MRI.getRegAllocationHints(Reg).second.size();
508   }
509 
510   for (const MachineBasicBlock &MBB : MF) {
511     for (const MachineInstr &MI : MBB) {
512       const unsigned Opc = MI.getOpcode();
513 
514       // Reductions may want or need to introduce implicit_defs, so don't count
515       // them.
516       // TODO: These probably should count in some way.
517       if (Opc == TargetOpcode::IMPLICIT_DEF ||
518           Opc == TargetOpcode::G_IMPLICIT_DEF)
519         continue;
520 
521       // Each instruction adds to the score
522       Score += 4;
523 
524       if (Opc == TargetOpcode::PHI || Opc == TargetOpcode::G_PHI ||
525           Opc == TargetOpcode::INLINEASM || Opc == TargetOpcode::INLINEASM_BR)
526         ++Score;
527 
528       if (MI.getFlags() != 0)
529         ++Score;
530 
531       // Increase weight for more operands.
532       for (const MachineOperand &MO : MI.operands()) {
533         ++Score;
534 
535         // Treat registers as more complex.
536         if (MO.isReg()) {
537           ++Score;
538 
539           // And subregisters as even more complex.
540           if (MO.getSubReg()) {
541             ++Score;
542             if (MO.isDef())
543               ++Score;
544           }
545         } else if (MO.isRegMask())
546           ++Score;
547       }
548     }
549   }
550 
551   return Score;
552 }
553 
554 uint64_t ReducerWorkItem::computeMIRComplexityScore() const {
555   uint64_t Score = 0;
556 
557   for (const Function &F : getModule()) {
558     if (auto *MF = MMI->getMachineFunction(F))
559       Score += computeMIRComplexityScoreImpl(*MF);
560   }
561 
562   return Score;
563 }
564