2018 lines · cpp
1//===- LiveDebugVariables.cpp - Tracking debug info variables -------------===//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-exception6//7//===----------------------------------------------------------------------===//8//9// This file implements the LiveDebugVariables analysis.10//11// Remove all DBG_VALUE instructions referencing virtual registers and replace12// them with a data structure tracking where live user variables are kept - in a13// virtual register or in a stack slot.14//15// Allow the data structure to be updated during register allocation when values16// are moved between registers and stack slots. Finally emit new DBG_VALUE17// instructions after register allocation is complete.18//19//===----------------------------------------------------------------------===//20 21#include "llvm/CodeGen/LiveDebugVariables.h"22#include "llvm/ADT/ArrayRef.h"23#include "llvm/ADT/DenseMap.h"24#include "llvm/ADT/IntervalMap.h"25#include "llvm/ADT/MapVector.h"26#include "llvm/ADT/STLExtras.h"27#include "llvm/ADT/SmallSet.h"28#include "llvm/ADT/SmallVector.h"29#include "llvm/ADT/Statistic.h"30#include "llvm/ADT/StringRef.h"31#include "llvm/BinaryFormat/Dwarf.h"32#include "llvm/CodeGen/LexicalScopes.h"33#include "llvm/CodeGen/LiveInterval.h"34#include "llvm/CodeGen/LiveIntervals.h"35#include "llvm/CodeGen/MachineBasicBlock.h"36#include "llvm/CodeGen/MachineDominators.h"37#include "llvm/CodeGen/MachineFunction.h"38#include "llvm/CodeGen/MachineInstr.h"39#include "llvm/CodeGen/MachineInstrBuilder.h"40#include "llvm/CodeGen/MachineOperand.h"41#include "llvm/CodeGen/MachinePassManager.h"42#include "llvm/CodeGen/MachineRegisterInfo.h"43#include "llvm/CodeGen/SlotIndexes.h"44#include "llvm/CodeGen/TargetInstrInfo.h"45#include "llvm/CodeGen/TargetOpcodes.h"46#include "llvm/CodeGen/TargetRegisterInfo.h"47#include "llvm/CodeGen/TargetSubtargetInfo.h"48#include "llvm/CodeGen/VirtRegMap.h"49#include "llvm/Config/llvm-config.h"50#include "llvm/IR/DebugInfoMetadata.h"51#include "llvm/IR/DebugLoc.h"52#include "llvm/IR/Function.h"53#include "llvm/InitializePasses.h"54#include "llvm/Pass.h"55#include "llvm/Support/Casting.h"56#include "llvm/Support/CommandLine.h"57#include "llvm/Support/Debug.h"58#include "llvm/Support/raw_ostream.h"59#include <algorithm>60#include <cassert>61#include <iterator>62#include <map>63#include <memory>64#include <optional>65#include <utility>66 67using namespace llvm;68 69#define DEBUG_TYPE "livedebugvars"70 71static cl::opt<bool>72EnableLDV("live-debug-variables", cl::init(true),73 cl::desc("Enable the live debug variables pass"), cl::Hidden);74 75STATISTIC(NumInsertedDebugValues, "Number of DBG_VALUEs inserted");76STATISTIC(NumInsertedDebugLabels, "Number of DBG_LABELs inserted");77 78char LiveDebugVariablesWrapperLegacy::ID = 0;79 80INITIALIZE_PASS_BEGIN(LiveDebugVariablesWrapperLegacy, DEBUG_TYPE,81 "Debug Variable Analysis", false, false)82INITIALIZE_PASS_DEPENDENCY(MachineDominatorTreeWrapperPass)83INITIALIZE_PASS_DEPENDENCY(LiveIntervalsWrapperPass)84INITIALIZE_PASS_END(LiveDebugVariablesWrapperLegacy, DEBUG_TYPE,85 "Debug Variable Analysis", false, true)86 87void LiveDebugVariablesWrapperLegacy::getAnalysisUsage(88 AnalysisUsage &AU) const {89 AU.addRequired<MachineDominatorTreeWrapperPass>();90 AU.addRequiredTransitive<LiveIntervalsWrapperPass>();91 AU.setPreservesAll();92 MachineFunctionPass::getAnalysisUsage(AU);93}94 95LiveDebugVariablesWrapperLegacy::LiveDebugVariablesWrapperLegacy()96 : MachineFunctionPass(ID) {97 initializeLiveDebugVariablesWrapperLegacyPass(98 *PassRegistry::getPassRegistry());99}100 101enum : unsigned { UndefLocNo = ~0U };102 103namespace {104/// Describes a debug variable value by location number and expression along105/// with some flags about the original usage of the location.106class DbgVariableValue {107public:108 DbgVariableValue(ArrayRef<unsigned> NewLocs, bool WasIndirect, bool WasList,109 const DIExpression &Expr)110 : WasIndirect(WasIndirect), WasList(WasList), Expression(&Expr) {111 assert(!(WasIndirect && WasList) &&112 "DBG_VALUE_LISTs should not be indirect.");113 SmallVector<unsigned> LocNoVec;114 for (unsigned LocNo : NewLocs) {115 auto It = find(LocNoVec, LocNo);116 if (It == LocNoVec.end())117 LocNoVec.push_back(LocNo);118 else {119 // Loc duplicates an element in LocNos; replace references to Op120 // with references to the duplicating element.121 unsigned OpIdx = LocNoVec.size();122 unsigned DuplicatingIdx = std::distance(LocNoVec.begin(), It);123 Expression =124 DIExpression::replaceArg(Expression, OpIdx, DuplicatingIdx);125 }126 }127 // FIXME: Debug values referencing 64+ unique machine locations are rare and128 // currently unsupported for performance reasons. If we can verify that129 // performance is acceptable for such debug values, we can increase the130 // bit-width of LocNoCount to 14 to enable up to 16384 unique machine131 // locations. We will also need to verify that this does not cause issues132 // with LiveDebugVariables' use of IntervalMap.133 if (LocNoVec.size() < 64) {134 LocNoCount = LocNoVec.size();135 if (LocNoCount > 0) {136 LocNos = std::make_unique<unsigned[]>(LocNoCount);137 llvm::copy(LocNoVec, loc_nos_begin());138 }139 } else {140 LLVM_DEBUG(dbgs() << "Found debug value with 64+ unique machine "141 "locations, dropping...\n");142 LocNoCount = 1;143 // Turn this into an undef debug value list; right now, the simplest form144 // of this is an expression with one arg, and an undef debug operand.145 Expression =146 DIExpression::get(Expr.getContext(), {dwarf::DW_OP_LLVM_arg, 0});147 if (auto FragmentInfoOpt = Expr.getFragmentInfo())148 Expression = *DIExpression::createFragmentExpression(149 Expression, FragmentInfoOpt->OffsetInBits,150 FragmentInfoOpt->SizeInBits);151 LocNos = std::make_unique<unsigned[]>(LocNoCount);152 LocNos[0] = UndefLocNo;153 }154 }155 156 DbgVariableValue() : LocNoCount(0), WasIndirect(false), WasList(false) {}157 DbgVariableValue(const DbgVariableValue &Other)158 : LocNoCount(Other.LocNoCount), WasIndirect(Other.getWasIndirect()),159 WasList(Other.getWasList()), Expression(Other.getExpression()) {160 if (Other.getLocNoCount()) {161 LocNos.reset(new unsigned[Other.getLocNoCount()]);162 std::copy(Other.loc_nos_begin(), Other.loc_nos_end(), loc_nos_begin());163 }164 }165 166 DbgVariableValue &operator=(const DbgVariableValue &Other) {167 if (this == &Other)168 return *this;169 if (Other.getLocNoCount()) {170 LocNos.reset(new unsigned[Other.getLocNoCount()]);171 std::copy(Other.loc_nos_begin(), Other.loc_nos_end(), loc_nos_begin());172 } else {173 LocNos.release();174 }175 LocNoCount = Other.getLocNoCount();176 WasIndirect = Other.getWasIndirect();177 WasList = Other.getWasList();178 Expression = Other.getExpression();179 return *this;180 }181 182 const DIExpression *getExpression() const { return Expression; }183 uint8_t getLocNoCount() const { return LocNoCount; }184 bool containsLocNo(unsigned LocNo) const {185 return is_contained(loc_nos(), LocNo);186 }187 bool getWasIndirect() const { return WasIndirect; }188 bool getWasList() const { return WasList; }189 bool isUndef() const { return LocNoCount == 0 || containsLocNo(UndefLocNo); }190 191 DbgVariableValue decrementLocNosAfterPivot(unsigned Pivot) const {192 SmallVector<unsigned, 4> NewLocNos;193 for (unsigned LocNo : loc_nos())194 NewLocNos.push_back(LocNo != UndefLocNo && LocNo > Pivot ? LocNo - 1195 : LocNo);196 return DbgVariableValue(NewLocNos, WasIndirect, WasList, *Expression);197 }198 199 DbgVariableValue remapLocNos(ArrayRef<unsigned> LocNoMap) const {200 SmallVector<unsigned> NewLocNos;201 for (unsigned LocNo : loc_nos())202 // Undef values don't exist in locations (and thus not in LocNoMap203 // either) so skip over them. See getLocationNo().204 NewLocNos.push_back(LocNo == UndefLocNo ? UndefLocNo : LocNoMap[LocNo]);205 return DbgVariableValue(NewLocNos, WasIndirect, WasList, *Expression);206 }207 208 DbgVariableValue changeLocNo(unsigned OldLocNo, unsigned NewLocNo) const {209 SmallVector<unsigned> NewLocNos;210 NewLocNos.assign(loc_nos_begin(), loc_nos_end());211 auto OldLocIt = find(NewLocNos, OldLocNo);212 assert(OldLocIt != NewLocNos.end() && "Old location must be present.");213 *OldLocIt = NewLocNo;214 return DbgVariableValue(NewLocNos, WasIndirect, WasList, *Expression);215 }216 217 bool hasLocNoGreaterThan(unsigned LocNo) const {218 return any_of(loc_nos(),219 [LocNo](unsigned ThisLocNo) { return ThisLocNo > LocNo; });220 }221 222 void printLocNos(llvm::raw_ostream &OS) const {223 for (const unsigned &Loc : loc_nos())224 OS << (&Loc == loc_nos_begin() ? " " : ", ") << Loc;225 }226 227 friend inline bool operator==(const DbgVariableValue &LHS,228 const DbgVariableValue &RHS) {229 if (std::tie(LHS.LocNoCount, LHS.WasIndirect, LHS.WasList,230 LHS.Expression) !=231 std::tie(RHS.LocNoCount, RHS.WasIndirect, RHS.WasList, RHS.Expression))232 return false;233 return std::equal(LHS.loc_nos_begin(), LHS.loc_nos_end(),234 RHS.loc_nos_begin());235 }236 237 friend inline bool operator!=(const DbgVariableValue &LHS,238 const DbgVariableValue &RHS) {239 return !(LHS == RHS);240 }241 242 unsigned *loc_nos_begin() { return LocNos.get(); }243 const unsigned *loc_nos_begin() const { return LocNos.get(); }244 unsigned *loc_nos_end() { return LocNos.get() + LocNoCount; }245 const unsigned *loc_nos_end() const { return LocNos.get() + LocNoCount; }246 ArrayRef<unsigned> loc_nos() const {247 return ArrayRef<unsigned>(LocNos.get(), LocNoCount);248 }249 250private:251 // IntervalMap requires the value object to be very small, to the extent252 // that we do not have enough room for an std::vector. Using a C-style array253 // (with a unique_ptr wrapper for convenience) allows us to optimize for this254 // specific case by packing the array size into only 6 bits (it is highly255 // unlikely that any debug value will need 64+ locations).256 std::unique_ptr<unsigned[]> LocNos;257 uint8_t LocNoCount : 6;258 bool WasIndirect : 1;259 bool WasList : 1;260 const DIExpression *Expression = nullptr;261};262} // namespace263 264/// Map of where a user value is live to that value.265using LocMap = IntervalMap<SlotIndex, DbgVariableValue, 4>;266 267/// Map of stack slot offsets for spilled locations.268/// Non-spilled locations are not added to the map.269using SpillOffsetMap = DenseMap<unsigned, unsigned>;270 271/// Cache to save the location where it can be used as the starting272/// position as input for calling MachineBasicBlock::SkipPHIsLabelsAndDebug.273/// This is to prevent MachineBasicBlock::SkipPHIsLabelsAndDebug from274/// repeatedly searching the same set of PHIs/Labels/Debug instructions275/// if it is called many times for the same block.276using BlockSkipInstsMap =277 DenseMap<MachineBasicBlock *, MachineBasicBlock::iterator>;278 279namespace {280 281/// A user value is a part of a debug info user variable.282///283/// A DBG_VALUE instruction notes that (a sub-register of) a virtual register284/// holds part of a user variable. The part is identified by a byte offset.285///286/// UserValues are grouped into equivalence classes for easier searching. Two287/// user values are related if they are held by the same virtual register. The288/// equivalence class is the transitive closure of that relation.289class UserValue {290 using LDVImpl = LiveDebugVariables::LDVImpl;291 292 const DILocalVariable *Variable; ///< The debug info variable we are part of.293 /// The part of the variable we describe.294 const std::optional<DIExpression::FragmentInfo> Fragment;295 DebugLoc dl; ///< The debug location for the variable. This is296 ///< used by dwarf writer to find lexical scope.297 UserValue *leader; ///< Equivalence class leader.298 UserValue *next = nullptr; ///< Next value in equivalence class, or null.299 300 /// Numbered locations referenced by locmap.301 SmallVector<MachineOperand, 4> locations;302 303 /// Map of slot indices where this value is live.304 LocMap locInts;305 306 /// Set of interval start indexes that have been trimmed to the307 /// lexical scope.308 SmallSet<SlotIndex, 2> trimmedDefs;309 310 /// Insert a DBG_VALUE into MBB at Idx for DbgValue.311 void insertDebugValue(MachineBasicBlock *MBB, SlotIndex StartIdx,312 SlotIndex StopIdx, DbgVariableValue DbgValue,313 ArrayRef<bool> LocSpills,314 ArrayRef<unsigned> SpillOffsets, LiveIntervals &LIS,315 const TargetInstrInfo &TII,316 const TargetRegisterInfo &TRI,317 BlockSkipInstsMap &BBSkipInstsMap);318 319 /// Replace OldLocNo ranges with NewRegs ranges where NewRegs320 /// is live. Returns true if any changes were made.321 bool splitLocation(unsigned OldLocNo, ArrayRef<Register> NewRegs,322 LiveIntervals &LIS);323 324public:325 /// Create a new UserValue.326 UserValue(const DILocalVariable *var,327 std::optional<DIExpression::FragmentInfo> Fragment, DebugLoc L,328 LocMap::Allocator &alloc)329 : Variable(var), Fragment(Fragment), dl(std::move(L)), leader(this),330 locInts(alloc) {}331 332 /// Get the leader of this value's equivalence class.333 UserValue *getLeader() {334 UserValue *l = leader;335 while (l != l->leader)336 l = l->leader;337 return leader = l;338 }339 340 /// Return the next UserValue in the equivalence class.341 UserValue *getNext() const { return next; }342 343 /// Merge equivalence classes.344 static UserValue *merge(UserValue *L1, UserValue *L2) {345 L2 = L2->getLeader();346 if (!L1)347 return L2;348 L1 = L1->getLeader();349 if (L1 == L2)350 return L1;351 // Splice L2 before L1's members.352 UserValue *End = L2;353 while (End->next) {354 End->leader = L1;355 End = End->next;356 }357 End->leader = L1;358 End->next = L1->next;359 L1->next = L2;360 return L1;361 }362 363 /// Return the location number that matches Loc.364 ///365 /// For undef values we always return location number UndefLocNo without366 /// inserting anything in locations. Since locations is a vector and the367 /// location number is the position in the vector and UndefLocNo is ~0,368 /// we would need a very big vector to put the value at the right position.369 unsigned getLocationNo(const MachineOperand &LocMO) {370 if (LocMO.isReg()) {371 if (LocMO.getReg() == 0)372 return UndefLocNo;373 // For register locations we dont care about use/def and other flags.374 for (unsigned i = 0, e = locations.size(); i != e; ++i)375 if (locations[i].isReg() &&376 locations[i].getReg() == LocMO.getReg() &&377 locations[i].getSubReg() == LocMO.getSubReg())378 return i;379 } else380 for (unsigned i = 0, e = locations.size(); i != e; ++i)381 if (LocMO.isIdenticalTo(locations[i]))382 return i;383 locations.push_back(LocMO);384 // We are storing a MachineOperand outside a MachineInstr.385 locations.back().clearParent();386 // Don't store def operands.387 if (locations.back().isReg()) {388 if (locations.back().isDef())389 locations.back().setIsDead(false);390 locations.back().setIsUse();391 }392 return locations.size() - 1;393 }394 395 /// Remove (recycle) a location number. If \p LocNo still is used by the396 /// locInts nothing is done.397 void removeLocationIfUnused(unsigned LocNo) {398 // Bail out if LocNo still is used.399 for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I) {400 const DbgVariableValue &DbgValue = I.value();401 if (DbgValue.containsLocNo(LocNo))402 return;403 }404 // Remove the entry in the locations vector, and adjust all references to405 // location numbers above the removed entry.406 locations.erase(locations.begin() + LocNo);407 for (LocMap::iterator I = locInts.begin(); I.valid(); ++I) {408 const DbgVariableValue &DbgValue = I.value();409 if (DbgValue.hasLocNoGreaterThan(LocNo))410 I.setValueUnchecked(DbgValue.decrementLocNosAfterPivot(LocNo));411 }412 }413 414 /// Ensure that all virtual register locations are mapped.415 void mapVirtRegs(LDVImpl *LDV);416 417 /// Add a definition point to this user value.418 void addDef(SlotIndex Idx, ArrayRef<MachineOperand> LocMOs, bool IsIndirect,419 bool IsList, const DIExpression &Expr) {420 SmallVector<unsigned> Locs;421 for (const MachineOperand &Op : LocMOs)422 Locs.push_back(getLocationNo(Op));423 DbgVariableValue DbgValue(Locs, IsIndirect, IsList, Expr);424 // Add a singular (Idx,Idx) -> value mapping.425 LocMap::iterator I = locInts.find(Idx);426 if (!I.valid() || I.start() != Idx)427 I.insert(Idx, Idx.getNextSlot(), std::move(DbgValue));428 else429 // A later DBG_VALUE at the same SlotIndex overrides the old location.430 I.setValue(std::move(DbgValue));431 }432 433 /// Extend the current definition as far as possible down.434 ///435 /// Stop when meeting an existing def or when leaving the live436 /// range of VNI. End points where VNI is no longer live are added to Kills.437 ///438 /// We only propagate DBG_VALUES locally here. LiveDebugValues performs a439 /// data-flow analysis to propagate them beyond basic block boundaries.440 ///441 /// \param Idx Starting point for the definition.442 /// \param DbgValue value to propagate.443 /// \param LiveIntervalInfo For each location number key in this map,444 /// restricts liveness to where the LiveRange has the value equal to the\445 /// VNInfo.446 /// \param [out] Kills Append end points of VNI's live range to Kills.447 /// \param LIS Live intervals analysis.448 void449 extendDef(SlotIndex Idx, DbgVariableValue DbgValue,450 SmallDenseMap<unsigned, std::pair<LiveRange *, const VNInfo *>>451 &LiveIntervalInfo,452 std::optional<std::pair<SlotIndex, SmallVector<unsigned>>> &Kills,453 LiveIntervals &LIS);454 455 /// The value in LI may be copies to other registers. Determine if456 /// any of the copies are available at the kill points, and add defs if457 /// possible.458 ///459 /// \param DbgValue Location number of LI->reg, and DIExpression.460 /// \param LocIntervals Scan for copies of the value for each location in the461 /// corresponding LiveInterval->reg.462 /// \param KilledAt The point where the range of DbgValue could be extended.463 /// \param [in,out] NewDefs Append (Idx, DbgValue) of inserted defs here.464 void addDefsFromCopies(465 DbgVariableValue DbgValue,466 SmallVectorImpl<std::pair<unsigned, LiveInterval *>> &LocIntervals,467 SlotIndex KilledAt,468 SmallVectorImpl<std::pair<SlotIndex, DbgVariableValue>> &NewDefs,469 MachineRegisterInfo &MRI, LiveIntervals &LIS);470 471 /// Compute the live intervals of all locations after collecting all their472 /// def points.473 void computeIntervals(MachineRegisterInfo &MRI, const TargetRegisterInfo &TRI,474 LiveIntervals &LIS, LexicalScopes &LS);475 476 /// Replace OldReg ranges with NewRegs ranges where NewRegs is477 /// live. Returns true if any changes were made.478 bool splitRegister(Register OldReg, ArrayRef<Register> NewRegs,479 LiveIntervals &LIS);480 481 /// Rewrite virtual register locations according to the provided virtual482 /// register map. Record the stack slot offsets for the locations that483 /// were spilled.484 void rewriteLocations(VirtRegMap &VRM, const MachineFunction &MF,485 const TargetInstrInfo &TII,486 const TargetRegisterInfo &TRI,487 SpillOffsetMap &SpillOffsets);488 489 /// Recreate DBG_VALUE instruction from data structures.490 void emitDebugValues(VirtRegMap *VRM, LiveIntervals &LIS,491 const TargetInstrInfo &TII,492 const TargetRegisterInfo &TRI,493 const SpillOffsetMap &SpillOffsets,494 BlockSkipInstsMap &BBSkipInstsMap);495 496 /// Return DebugLoc of this UserValue.497 const DebugLoc &getDebugLoc() { return dl; }498 499 void print(raw_ostream &, const TargetRegisterInfo *);500};501 502/// A user label is a part of a debug info user label.503class UserLabel {504 const DILabel *Label; ///< The debug info label we are part of.505 DebugLoc dl; ///< The debug location for the label. This is506 ///< used by dwarf writer to find lexical scope.507 SlotIndex loc; ///< Slot used by the debug label.508 509 /// Insert a DBG_LABEL into MBB at Idx.510 void insertDebugLabel(MachineBasicBlock *MBB, SlotIndex Idx,511 LiveIntervals &LIS, const TargetInstrInfo &TII,512 BlockSkipInstsMap &BBSkipInstsMap);513 514public:515 /// Create a new UserLabel.516 UserLabel(const DILabel *label, DebugLoc L, SlotIndex Idx)517 : Label(label), dl(std::move(L)), loc(Idx) {}518 519 /// Does this UserLabel match the parameters?520 bool matches(const DILabel *L, const DILocation *IA,521 const SlotIndex Index) const {522 return Label == L && dl->getInlinedAt() == IA && loc == Index;523 }524 525 /// Recreate DBG_LABEL instruction from data structures.526 void emitDebugLabel(LiveIntervals &LIS, const TargetInstrInfo &TII,527 BlockSkipInstsMap &BBSkipInstsMap);528 529 /// Return DebugLoc of this UserLabel.530 const DebugLoc &getDebugLoc() { return dl; }531 532 void print(raw_ostream &, const TargetRegisterInfo *);533};534 535} // end anonymous namespace536 537namespace llvm {538 539class LiveDebugVariables::LDVImpl {540 LocMap::Allocator allocator;541 MachineFunction *MF = nullptr;542 LiveIntervals *LIS;543 const TargetRegisterInfo *TRI;544 545 /// Position and VReg of a PHI instruction during register allocation.546 struct PHIValPos {547 SlotIndex SI; /// Slot where this PHI occurs.548 Register Reg; /// VReg this PHI occurs in.549 unsigned SubReg; /// Qualifiying subregister for Reg.550 };551 552 /// Map from debug instruction number to PHI position during allocation.553 std::map<unsigned, PHIValPos> PHIValToPos;554 /// Index of, for each VReg, which debug instruction numbers and corresponding555 /// PHIs are sensitive to splitting. Each VReg may have multiple PHI defs,556 /// at different positions.557 DenseMap<Register, std::vector<unsigned>> RegToPHIIdx;558 559 /// Record for any debug instructions unlinked from their blocks during560 /// regalloc. Stores the instr and it's location, so that they can be561 /// re-inserted after regalloc is over.562 struct InstrPos {563 MachineInstr *MI; ///< Debug instruction, unlinked from it's block.564 SlotIndex Idx; ///< Slot position where MI should be re-inserted.565 MachineBasicBlock *MBB; ///< Block that MI was in.566 };567 568 /// Collection of stored debug instructions, preserved until after regalloc.569 SmallVector<InstrPos, 32> StashedDebugInstrs;570 571 /// Whether emitDebugValues is called.572 bool EmitDone = false;573 574 /// Whether the machine function is modified during the pass.575 bool ModifiedMF = false;576 577 /// All allocated UserValue instances.578 SmallVector<std::unique_ptr<UserValue>, 8> userValues;579 580 /// All allocated UserLabel instances.581 SmallVector<std::unique_ptr<UserLabel>, 2> userLabels;582 583 /// Map virtual register to eq class leader.584 using VRMap = DenseMap<Register, UserValue *>;585 VRMap virtRegToEqClass;586 587 /// Map to find existing UserValue instances.588 using UVMap = DenseMap<DebugVariable, UserValue *>;589 UVMap userVarMap;590 591 /// Find or create a UserValue.592 UserValue *getUserValue(const DILocalVariable *Var,593 std::optional<DIExpression::FragmentInfo> Fragment,594 const DebugLoc &DL);595 596 /// Find the EC leader for VirtReg or null.597 UserValue *lookupVirtReg(Register VirtReg);598 599 /// Add DBG_VALUE instruction to our maps.600 ///601 /// \param MI DBG_VALUE instruction602 /// \param Idx Last valid SLotIndex before instruction.603 ///604 /// \returns True if the DBG_VALUE instruction should be deleted.605 bool handleDebugValue(MachineInstr &MI, SlotIndex Idx);606 607 /// Track variable location debug instructions while using the instruction608 /// referencing implementation. Such debug instructions do not need to be609 /// updated during regalloc because they identify instructions rather than610 /// register locations. However, they needs to be removed from the611 /// MachineFunction during regalloc, then re-inserted later, to avoid612 /// disrupting the allocator.613 ///614 /// \param MI Any DBG_VALUE / DBG_INSTR_REF / DBG_PHI instruction615 /// \param Idx Last valid SlotIndex before instruction616 ///617 /// \returns Iterator to continue processing from after unlinking.618 MachineBasicBlock::iterator handleDebugInstr(MachineInstr &MI, SlotIndex Idx);619 620 /// Add DBG_LABEL instruction to UserLabel.621 ///622 /// \param MI DBG_LABEL instruction623 /// \param Idx Last valid SlotIndex before instruction.624 ///625 /// \returns True if the DBG_LABEL instruction should be deleted.626 bool handleDebugLabel(MachineInstr &MI, SlotIndex Idx);627 628 /// Collect and erase all DBG_VALUE instructions, adding a UserValue def629 /// for each instruction.630 ///631 /// \param mf MachineFunction to be scanned.632 /// \param InstrRef Whether to operate in instruction referencing mode. If633 /// true, most of LiveDebugVariables doesn't run.634 ///635 /// \returns True if any debug values were found.636 bool collectDebugValues(MachineFunction &mf, bool InstrRef);637 638 /// Compute the live intervals of all user values after collecting all639 /// their def points.640 void computeIntervals();641 642public:643 LDVImpl(LiveIntervals *LIS) : LIS(LIS) {}644 645 bool runOnMachineFunction(MachineFunction &mf, bool InstrRef);646 647 /// Release all memory.648 void clear() {649 MF = nullptr;650 PHIValToPos.clear();651 RegToPHIIdx.clear();652 StashedDebugInstrs.clear();653 userValues.clear();654 userLabels.clear();655 virtRegToEqClass.clear();656 userVarMap.clear();657 // Make sure we call emitDebugValues if the machine function was modified.658 assert((!ModifiedMF || EmitDone) &&659 "Dbg values are not emitted in LDV");660 EmitDone = false;661 ModifiedMF = false;662 }663 664 /// Map virtual register to an equivalence class.665 void mapVirtReg(Register VirtReg, UserValue *EC);666 667 /// Replace any PHI referring to OldReg with its corresponding NewReg, if668 /// present.669 void splitPHIRegister(Register OldReg, ArrayRef<Register> NewRegs);670 671 /// Replace all references to OldReg with NewRegs.672 void splitRegister(Register OldReg, ArrayRef<Register> NewRegs);673 674 /// Recreate DBG_VALUE instruction from data structures.675 void emitDebugValues(VirtRegMap *VRM);676 677 void print(raw_ostream&);678};679 680/// Implementation of the LiveDebugVariables pass.681 682LiveDebugVariables::LiveDebugVariables() = default;683LiveDebugVariables::~LiveDebugVariables() = default;684LiveDebugVariables::LiveDebugVariables(LiveDebugVariables &&) = default;685 686} // namespace llvm687 688static void printDebugLoc(const DebugLoc &DL, raw_ostream &CommentOS,689 const LLVMContext &Ctx) {690 if (!DL)691 return;692 693 auto *Scope = cast<DIScope>(DL.getScope());694 // Omit the directory, because it's likely to be long and uninteresting.695 CommentOS << Scope->getFilename();696 CommentOS << ':' << DL.getLine();697 if (DL.getCol() != 0)698 CommentOS << ':' << DL.getCol();699 700 DebugLoc InlinedAtDL = DL.getInlinedAt();701 if (!InlinedAtDL)702 return;703 704 CommentOS << " @[ ";705 printDebugLoc(InlinedAtDL, CommentOS, Ctx);706 CommentOS << " ]";707}708 709static void printExtendedName(raw_ostream &OS, const DINode *Node,710 const DILocation *DL) {711 const LLVMContext &Ctx = Node->getContext();712 StringRef Res;713 unsigned Line = 0;714 if (const auto *V = dyn_cast<const DILocalVariable>(Node)) {715 Res = V->getName();716 Line = V->getLine();717 } else if (const auto *L = dyn_cast<const DILabel>(Node)) {718 Res = L->getName();719 Line = L->getLine();720 }721 722 if (!Res.empty())723 OS << Res << "," << Line;724 auto *InlinedAt = DL ? DL->getInlinedAt() : nullptr;725 if (InlinedAt) {726 if (DebugLoc InlinedAtDL = InlinedAt) {727 OS << " @[";728 printDebugLoc(InlinedAtDL, OS, Ctx);729 OS << "]";730 }731 }732}733 734void UserValue::print(raw_ostream &OS, const TargetRegisterInfo *TRI) {735 OS << "!\"";736 printExtendedName(OS, Variable, dl);737 738 OS << "\"\t";739 for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I) {740 OS << " [" << I.start() << ';' << I.stop() << "):";741 if (I.value().isUndef())742 OS << " undef";743 else {744 I.value().printLocNos(OS);745 if (I.value().getWasIndirect())746 OS << " ind";747 else if (I.value().getWasList())748 OS << " list";749 }750 }751 for (unsigned i = 0, e = locations.size(); i != e; ++i) {752 OS << " Loc" << i << '=';753 locations[i].print(OS, TRI);754 }755 OS << '\n';756}757 758void UserLabel::print(raw_ostream &OS, const TargetRegisterInfo *TRI) {759 OS << "!\"";760 printExtendedName(OS, Label, dl);761 762 OS << "\"\t";763 OS << loc;764 OS << '\n';765}766 767void LiveDebugVariables::LDVImpl::print(raw_ostream &OS) {768 OS << "********** DEBUG VARIABLES **********\n";769 for (auto &userValue : userValues)770 userValue->print(OS, TRI);771 OS << "********** DEBUG LABELS **********\n";772 for (auto &userLabel : userLabels)773 userLabel->print(OS, TRI);774}775 776void UserValue::mapVirtRegs(LiveDebugVariables::LDVImpl *LDV) {777 for (const MachineOperand &MO : locations)778 if (MO.isReg() && MO.getReg().isVirtual())779 LDV->mapVirtReg(MO.getReg(), this);780}781 782UserValue *LiveDebugVariables::LDVImpl::getUserValue(783 const DILocalVariable *Var,784 std::optional<DIExpression::FragmentInfo> Fragment, const DebugLoc &DL) {785 // FIXME: Handle partially overlapping fragments. See786 // https://reviews.llvm.org/D70121#1849741.787 DebugVariable ID(Var, Fragment, DL->getInlinedAt());788 UserValue *&UV = userVarMap[ID];789 if (!UV) {790 userValues.push_back(791 std::make_unique<UserValue>(Var, Fragment, DL, allocator));792 UV = userValues.back().get();793 }794 return UV;795}796 797void LiveDebugVariables::LDVImpl::mapVirtReg(Register VirtReg, UserValue *EC) {798 assert(VirtReg.isVirtual() && "Only map VirtRegs");799 UserValue *&Leader = virtRegToEqClass[VirtReg];800 Leader = UserValue::merge(Leader, EC);801}802 803UserValue *LiveDebugVariables::LDVImpl::lookupVirtReg(Register VirtReg) {804 if (UserValue *UV = virtRegToEqClass.lookup(VirtReg))805 return UV->getLeader();806 return nullptr;807}808 809bool LiveDebugVariables::LDVImpl::handleDebugValue(MachineInstr &MI,810 SlotIndex Idx) {811 // DBG_VALUE loc, offset, variable, expr812 // DBG_VALUE_LIST variable, expr, locs...813 if (!MI.isDebugValue()) {814 LLVM_DEBUG(dbgs() << "Can't handle non-DBG_VALUE*: " << MI);815 return false;816 }817 if (!MI.getDebugVariableOp().isMetadata()) {818 LLVM_DEBUG(dbgs() << "Can't handle DBG_VALUE* with invalid variable: "819 << MI);820 return false;821 }822 if (MI.isNonListDebugValue() &&823 (MI.getNumOperands() != 4 ||824 !(MI.getDebugOffset().isImm() || MI.getDebugOffset().isReg()))) {825 LLVM_DEBUG(dbgs() << "Can't handle malformed DBG_VALUE: " << MI);826 return false;827 }828 829 // Detect invalid DBG_VALUE instructions, with a debug-use of a virtual830 // register that hasn't been defined yet. If we do not remove those here, then831 // the re-insertion of the DBG_VALUE instruction after register allocation832 // will be incorrect.833 bool Discard = false;834 for (const MachineOperand &Op : MI.debug_operands()) {835 if (Op.isReg() && Op.getReg().isVirtual()) {836 const Register Reg = Op.getReg();837 if (!LIS->hasInterval(Reg)) {838 // The DBG_VALUE is described by a virtual register that does not have a839 // live interval. Discard the DBG_VALUE.840 Discard = true;841 LLVM_DEBUG(dbgs() << "Discarding debug info (no LIS interval): " << Idx842 << " " << MI);843 } else {844 // The DBG_VALUE is only valid if either Reg is live out from Idx, or845 // Reg is defined dead at Idx (where Idx is the slot index for the846 // instruction preceding the DBG_VALUE).847 const LiveInterval &LI = LIS->getInterval(Reg);848 LiveQueryResult LRQ = LI.Query(Idx);849 if (!LRQ.valueOutOrDead()) {850 // We have found a DBG_VALUE with the value in a virtual register that851 // is not live. Discard the DBG_VALUE.852 Discard = true;853 LLVM_DEBUG(dbgs() << "Discarding debug info (reg not live): " << Idx854 << " " << MI);855 }856 }857 }858 }859 860 // Get or create the UserValue for (variable,offset) here.861 bool IsIndirect = MI.isDebugOffsetImm();862 if (IsIndirect)863 assert(MI.getDebugOffset().getImm() == 0 &&864 "DBG_VALUE with nonzero offset");865 bool IsList = MI.isDebugValueList();866 const DILocalVariable *Var = MI.getDebugVariable();867 const DIExpression *Expr = MI.getDebugExpression();868 UserValue *UV = getUserValue(Var, Expr->getFragmentInfo(), MI.getDebugLoc());869 if (!Discard)870 UV->addDef(Idx,871 ArrayRef<MachineOperand>(MI.debug_operands().begin(),872 MI.debug_operands().end()),873 IsIndirect, IsList, *Expr);874 else {875 MachineOperand MO = MachineOperand::CreateReg(0U, false);876 MO.setIsDebug();877 // We should still pass a list the same size as MI.debug_operands() even if878 // all MOs are undef, so that DbgVariableValue can correctly adjust the879 // expression while removing the duplicated undefs.880 SmallVector<MachineOperand, 4> UndefMOs(MI.getNumDebugOperands(), MO);881 UV->addDef(Idx, UndefMOs, false, IsList, *Expr);882 }883 return true;884}885 886MachineBasicBlock::iterator887LiveDebugVariables::LDVImpl::handleDebugInstr(MachineInstr &MI, SlotIndex Idx) {888 assert(MI.isDebugValueLike() || MI.isDebugPHI());889 890 // In instruction referencing mode, there should be no DBG_VALUE instructions891 // that refer to virtual registers. They might still refer to constants.892 if (MI.isDebugValueLike())893 assert(none_of(MI.debug_operands(),894 [](const MachineOperand &MO) {895 return MO.isReg() && MO.getReg().isVirtual();896 }) &&897 "MIs should not refer to Virtual Registers in InstrRef mode.");898 899 // Unlink the instruction, store it in the debug instructions collection.900 auto NextInst = std::next(MI.getIterator());901 auto *MBB = MI.getParent();902 MI.removeFromParent();903 StashedDebugInstrs.push_back({&MI, Idx, MBB});904 return NextInst;905}906 907bool LiveDebugVariables::LDVImpl::handleDebugLabel(MachineInstr &MI,908 SlotIndex Idx) {909 // DBG_LABEL label910 if (MI.getNumOperands() != 1 || !MI.getOperand(0).isMetadata()) {911 LLVM_DEBUG(dbgs() << "Can't handle " << MI);912 return false;913 }914 915 // Get or create the UserLabel for label here.916 const DILabel *Label = MI.getDebugLabel();917 const DebugLoc &DL = MI.getDebugLoc();918 bool Found = false;919 for (auto const &L : userLabels) {920 if (L->matches(Label, DL->getInlinedAt(), Idx)) {921 Found = true;922 break;923 }924 }925 if (!Found)926 userLabels.push_back(std::make_unique<UserLabel>(Label, DL, Idx));927 928 return true;929}930 931bool LiveDebugVariables::LDVImpl::collectDebugValues(MachineFunction &mf,932 bool InstrRef) {933 bool Changed = false;934 for (MachineBasicBlock &MBB : mf) {935 for (MachineBasicBlock::iterator MBBI = MBB.begin(), MBBE = MBB.end();936 MBBI != MBBE;) {937 // Use the first debug instruction in the sequence to get a SlotIndex938 // for following consecutive debug instructions.939 if (!MBBI->isDebugOrPseudoInstr()) {940 ++MBBI;941 continue;942 }943 // Debug instructions has no slot index. Use the previous944 // non-debug instruction's SlotIndex as its SlotIndex.945 SlotIndex Idx =946 MBBI == MBB.begin()947 ? LIS->getMBBStartIdx(&MBB)948 : LIS->getInstructionIndex(*std::prev(MBBI)).getRegSlot();949 // Handle consecutive debug instructions with the same slot index.950 do {951 // In instruction referencing mode, pass each instr to handleDebugInstr952 // to be unlinked. Ignore DBG_VALUE_LISTs -- they refer to vregs, and953 // need to go through the normal live interval splitting process.954 if (InstrRef && (MBBI->isNonListDebugValue() || MBBI->isDebugPHI() ||955 MBBI->isDebugRef())) {956 MBBI = handleDebugInstr(*MBBI, Idx);957 Changed = true;958 // In normal debug mode, use the dedicated DBG_VALUE / DBG_LABEL handler959 // to track things through register allocation, and erase the instr.960 } else if ((MBBI->isDebugValue() && handleDebugValue(*MBBI, Idx)) ||961 (MBBI->isDebugLabel() && handleDebugLabel(*MBBI, Idx))) {962 MBBI = MBB.erase(MBBI);963 Changed = true;964 } else965 ++MBBI;966 } while (MBBI != MBBE && MBBI->isDebugOrPseudoInstr());967 }968 }969 return Changed;970}971 972void UserValue::extendDef(973 SlotIndex Idx, DbgVariableValue DbgValue,974 SmallDenseMap<unsigned, std::pair<LiveRange *, const VNInfo *>>975 &LiveIntervalInfo,976 std::optional<std::pair<SlotIndex, SmallVector<unsigned>>> &Kills,977 LiveIntervals &LIS) {978 SlotIndex Start = Idx;979 MachineBasicBlock *MBB = LIS.getMBBFromIndex(Start);980 SlotIndex Stop = LIS.getMBBEndIdx(MBB);981 LocMap::iterator I = locInts.find(Start);982 983 // Limit to the intersection of the VNIs' live ranges.984 for (auto &LII : LiveIntervalInfo) {985 LiveRange *LR = LII.second.first;986 assert(LR && LII.second.second && "Missing range info for Idx.");987 LiveInterval::Segment *Segment = LR->getSegmentContaining(Start);988 assert(Segment && Segment->valno == LII.second.second &&989 "Invalid VNInfo for Idx given?");990 if (Segment->end < Stop) {991 Stop = Segment->end;992 Kills = {Stop, {LII.first}};993 } else if (Segment->end == Stop && Kills) {994 // If multiple locations end at the same place, track all of them in995 // Kills.996 Kills->second.push_back(LII.first);997 }998 }999 1000 // There could already be a short def at Start.1001 if (I.valid() && I.start() <= Start) {1002 // Stop when meeting a different location or an already extended interval.1003 Start = Start.getNextSlot();1004 if (I.value() != DbgValue || I.stop() != Start) {1005 // Clear `Kills`, as we have a new def available.1006 Kills = std::nullopt;1007 return;1008 }1009 // This is a one-slot placeholder. Just skip it.1010 ++I;1011 }1012 1013 // Limited by the next def.1014 if (I.valid() && I.start() < Stop) {1015 Stop = I.start();1016 // Clear `Kills`, as we have a new def available.1017 Kills = std::nullopt;1018 }1019 1020 if (Start < Stop) {1021 DbgVariableValue ExtDbgValue(DbgValue);1022 I.insert(Start, Stop, std::move(ExtDbgValue));1023 }1024}1025 1026void UserValue::addDefsFromCopies(1027 DbgVariableValue DbgValue,1028 SmallVectorImpl<std::pair<unsigned, LiveInterval *>> &LocIntervals,1029 SlotIndex KilledAt,1030 SmallVectorImpl<std::pair<SlotIndex, DbgVariableValue>> &NewDefs,1031 MachineRegisterInfo &MRI, LiveIntervals &LIS) {1032 // Don't track copies from physregs, there are too many uses.1033 if (any_of(LocIntervals,1034 [](auto LocI) { return !LocI.second->reg().isVirtual(); }))1035 return;1036 1037 // Collect all the (vreg, valno) pairs that are copies of LI.1038 SmallDenseMap<unsigned,1039 SmallVector<std::pair<LiveInterval *, const VNInfo *>, 4>>1040 CopyValues;1041 for (auto &LocInterval : LocIntervals) {1042 unsigned LocNo = LocInterval.first;1043 LiveInterval *LI = LocInterval.second;1044 for (MachineOperand &MO : MRI.use_nodbg_operands(LI->reg())) {1045 MachineInstr *MI = MO.getParent();1046 // Copies of the full value.1047 if (MO.getSubReg() || !MI->isCopy())1048 continue;1049 Register DstReg = MI->getOperand(0).getReg();1050 1051 // Don't follow copies to physregs. These are usually setting up call1052 // arguments, and the argument registers are always call clobbered. We are1053 // better off in the source register which could be a callee-saved1054 // register, or it could be spilled.1055 if (!DstReg.isVirtual())1056 continue;1057 1058 // Is the value extended to reach this copy? If not, another def may be1059 // blocking it, or we are looking at a wrong value of LI.1060 SlotIndex Idx = LIS.getInstructionIndex(*MI);1061 LocMap::iterator I = locInts.find(Idx.getRegSlot(true));1062 if (!I.valid() || I.value() != DbgValue)1063 continue;1064 1065 if (!LIS.hasInterval(DstReg))1066 continue;1067 LiveInterval *DstLI = &LIS.getInterval(DstReg);1068 const VNInfo *DstVNI = DstLI->getVNInfoAt(Idx.getRegSlot());1069 assert(DstVNI && DstVNI->def == Idx.getRegSlot() && "Bad copy value");1070 CopyValues[LocNo].push_back(std::make_pair(DstLI, DstVNI));1071 }1072 }1073 1074 if (CopyValues.empty())1075 return;1076 1077#if !defined(NDEBUG)1078 for (auto &LocInterval : LocIntervals)1079 LLVM_DEBUG(dbgs() << "Got " << CopyValues[LocInterval.first].size()1080 << " copies of " << *LocInterval.second << '\n');1081#endif1082 1083 // Try to add defs of the copied values for the kill point. Check that there1084 // isn't already a def at Idx.1085 LocMap::iterator I = locInts.find(KilledAt);1086 if (I.valid() && I.start() <= KilledAt)1087 return;1088 DbgVariableValue NewValue(DbgValue);1089 for (auto &LocInterval : LocIntervals) {1090 unsigned LocNo = LocInterval.first;1091 bool FoundCopy = false;1092 for (auto &LIAndVNI : CopyValues[LocNo]) {1093 LiveInterval *DstLI = LIAndVNI.first;1094 const VNInfo *DstVNI = LIAndVNI.second;1095 if (DstLI->getVNInfoAt(KilledAt) != DstVNI)1096 continue;1097 LLVM_DEBUG(dbgs() << "Kill at " << KilledAt << " covered by valno #"1098 << DstVNI->id << " in " << *DstLI << '\n');1099 MachineInstr *CopyMI = LIS.getInstructionFromIndex(DstVNI->def);1100 assert(CopyMI && CopyMI->isCopy() && "Bad copy value");1101 unsigned NewLocNo = getLocationNo(CopyMI->getOperand(0));1102 NewValue = NewValue.changeLocNo(LocNo, NewLocNo);1103 FoundCopy = true;1104 break;1105 }1106 // If there are any killed locations we can't find a copy for, we can't1107 // extend the variable value.1108 if (!FoundCopy)1109 return;1110 }1111 I.insert(KilledAt, KilledAt.getNextSlot(), NewValue);1112 NewDefs.push_back(std::make_pair(KilledAt, NewValue));1113}1114 1115void UserValue::computeIntervals(MachineRegisterInfo &MRI,1116 const TargetRegisterInfo &TRI,1117 LiveIntervals &LIS, LexicalScopes &LS) {1118 SmallVector<std::pair<SlotIndex, DbgVariableValue>, 16> Defs;1119 1120 // Collect all defs to be extended (Skipping undefs).1121 for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I)1122 if (!I.value().isUndef())1123 Defs.push_back(std::make_pair(I.start(), I.value()));1124 1125 // Extend all defs, and possibly add new ones along the way.1126 for (unsigned i = 0; i != Defs.size(); ++i) {1127 SlotIndex Idx = Defs[i].first;1128 DbgVariableValue DbgValue = Defs[i].second;1129 SmallDenseMap<unsigned, std::pair<LiveRange *, const VNInfo *>> LIs;1130 bool ShouldExtendDef = false;1131 for (unsigned LocNo : DbgValue.loc_nos()) {1132 const MachineOperand &LocMO = locations[LocNo];1133 if (!LocMO.isReg() || !LocMO.getReg().isVirtual()) {1134 ShouldExtendDef |= !LocMO.isReg();1135 continue;1136 }1137 ShouldExtendDef = true;1138 LiveInterval *LI = nullptr;1139 const VNInfo *VNI = nullptr;1140 if (LIS.hasInterval(LocMO.getReg())) {1141 LI = &LIS.getInterval(LocMO.getReg());1142 VNI = LI->getVNInfoAt(Idx);1143 }1144 if (LI && VNI)1145 LIs[LocNo] = {LI, VNI};1146 }1147 if (ShouldExtendDef) {1148 std::optional<std::pair<SlotIndex, SmallVector<unsigned>>> Kills;1149 extendDef(Idx, DbgValue, LIs, Kills, LIS);1150 1151 if (Kills) {1152 SmallVector<std::pair<unsigned, LiveInterval *>, 2> KilledLocIntervals;1153 bool AnySubreg = false;1154 for (unsigned LocNo : Kills->second) {1155 const MachineOperand &LocMO = this->locations[LocNo];1156 if (LocMO.getSubReg()) {1157 AnySubreg = true;1158 break;1159 }1160 LiveInterval *LI = &LIS.getInterval(LocMO.getReg());1161 KilledLocIntervals.push_back({LocNo, LI});1162 }1163 1164 // FIXME: Handle sub-registers in addDefsFromCopies. The problem is that1165 // if the original location for example is %vreg0:sub_hi, and we find a1166 // full register copy in addDefsFromCopies (at the moment it only1167 // handles full register copies), then we must add the sub1 sub-register1168 // index to the new location. However, that is only possible if the new1169 // virtual register is of the same regclass (or if there is an1170 // equivalent sub-register in that regclass). For now, simply skip1171 // handling copies if a sub-register is involved.1172 if (!AnySubreg)1173 addDefsFromCopies(DbgValue, KilledLocIntervals, Kills->first, Defs,1174 MRI, LIS);1175 }1176 }1177 1178 // For physregs, we only mark the start slot idx. DwarfDebug will see it1179 // as if the DBG_VALUE is valid up until the end of the basic block, or1180 // the next def of the physical register. So we do not need to extend the1181 // range. It might actually happen that the DBG_VALUE is the last use of1182 // the physical register (e.g. if this is an unused input argument to a1183 // function).1184 }1185 1186 // The computed intervals may extend beyond the range of the debug1187 // location's lexical scope. In this case, splitting of an interval1188 // can result in an interval outside of the scope being created,1189 // causing extra unnecessary DBG_VALUEs to be emitted. To prevent1190 // this, trim the intervals to the lexical scope in the case of inlined1191 // variables, since heavy inlining may cause production of dramatically big1192 // number of DBG_VALUEs to be generated.1193 if (!dl.getInlinedAt())1194 return;1195 1196 LexicalScope *Scope = LS.findLexicalScope(dl);1197 if (!Scope)1198 return;1199 1200 SlotIndex PrevEnd;1201 LocMap::iterator I = locInts.begin();1202 1203 // Iterate over the lexical scope ranges. Each time round the loop1204 // we check the intervals for overlap with the end of the previous1205 // range and the start of the next. The first range is handled as1206 // a special case where there is no PrevEnd.1207 for (const InsnRange &Range : Scope->getRanges()) {1208 SlotIndex RStart = LIS.getInstructionIndex(*Range.first);1209 SlotIndex REnd = LIS.getInstructionIndex(*Range.second);1210 1211 // Variable locations at the first instruction of a block should be1212 // based on the block's SlotIndex, not the first instruction's index.1213 if (Range.first == Range.first->getParent()->begin())1214 RStart = LIS.getSlotIndexes()->getIndexBefore(*Range.first);1215 1216 // At the start of each iteration I has been advanced so that1217 // I.stop() >= PrevEnd. Check for overlap.1218 if (PrevEnd && I.start() < PrevEnd) {1219 SlotIndex IStop = I.stop();1220 DbgVariableValue DbgValue = I.value();1221 1222 // Stop overlaps previous end - trim the end of the interval to1223 // the scope range.1224 I.setStopUnchecked(PrevEnd);1225 ++I;1226 1227 // If the interval also overlaps the start of the "next" (i.e.1228 // current) range create a new interval for the remainder (which1229 // may be further trimmed).1230 if (RStart < IStop)1231 I.insert(RStart, IStop, DbgValue);1232 }1233 1234 // Advance I so that I.stop() >= RStart, and check for overlap.1235 I.advanceTo(RStart);1236 if (!I.valid())1237 return;1238 1239 if (I.start() < RStart) {1240 // Interval start overlaps range - trim to the scope range.1241 I.setStartUnchecked(RStart);1242 // Remember that this interval was trimmed.1243 trimmedDefs.insert(RStart);1244 }1245 1246 // The end of a lexical scope range is the last instruction in the1247 // range. To convert to an interval we need the index of the1248 // instruction after it.1249 REnd = REnd.getNextIndex();1250 1251 // Advance I to first interval outside current range.1252 I.advanceTo(REnd);1253 if (!I.valid())1254 return;1255 1256 PrevEnd = REnd;1257 }1258 1259 // Check for overlap with end of final range.1260 if (PrevEnd && I.start() < PrevEnd)1261 I.setStopUnchecked(PrevEnd);1262}1263 1264void LiveDebugVariables::LDVImpl::computeIntervals() {1265 LexicalScopes LS;1266 LS.scanFunction(*MF);1267 1268 for (const auto &UV : userValues) {1269 UV->computeIntervals(MF->getRegInfo(), *TRI, *LIS, LS);1270 UV->mapVirtRegs(this);1271 }1272}1273 1274bool LiveDebugVariables::LDVImpl::runOnMachineFunction(MachineFunction &mf,1275 bool InstrRef) {1276 clear();1277 MF = &mf;1278 TRI = mf.getSubtarget().getRegisterInfo();1279 LLVM_DEBUG(dbgs() << "********** COMPUTING LIVE DEBUG VARIABLES: "1280 << mf.getName() << " **********\n");1281 1282 bool Changed = collectDebugValues(mf, InstrRef);1283 computeIntervals();1284 LLVM_DEBUG(print(dbgs()));1285 1286 // Collect the set of VReg / SlotIndexs where PHIs occur; index the sensitive1287 // VRegs too, for when we're notified of a range split.1288 SlotIndexes *Slots = LIS->getSlotIndexes();1289 for (const auto &PHIIt : MF->DebugPHIPositions) {1290 const MachineFunction::DebugPHIRegallocPos &Position = PHIIt.second;1291 MachineBasicBlock *MBB = Position.MBB;1292 Register Reg = Position.Reg;1293 unsigned SubReg = Position.SubReg;1294 SlotIndex SI = Slots->getMBBStartIdx(MBB);1295 PHIValPos VP = {SI, Reg, SubReg};1296 PHIValToPos.insert(std::make_pair(PHIIt.first, VP));1297 RegToPHIIdx[Reg].push_back(PHIIt.first);1298 }1299 1300 ModifiedMF = Changed;1301 return Changed;1302}1303 1304static void removeDebugInstrs(MachineFunction &mf) {1305 for (MachineBasicBlock &MBB : mf) {1306 for (MachineInstr &MI : llvm::make_early_inc_range(MBB))1307 if (MI.isDebugInstr())1308 MBB.erase(&MI);1309 }1310}1311 1312bool LiveDebugVariablesWrapperLegacy::runOnMachineFunction(1313 MachineFunction &mf) {1314 auto *LIS = &getAnalysis<LiveIntervalsWrapperPass>().getLIS();1315 1316 Impl = std::make_unique<LiveDebugVariables>();1317 Impl->analyze(mf, LIS);1318 return false;1319}1320 1321AnalysisKey LiveDebugVariablesAnalysis::Key;1322 1323LiveDebugVariables1324LiveDebugVariablesAnalysis::run(MachineFunction &MF,1325 MachineFunctionAnalysisManager &MFAM) {1326 MFPropsModifier _(*this, MF);1327 1328 auto *LIS = &MFAM.getResult<LiveIntervalsAnalysis>(MF);1329 LiveDebugVariables LDV;1330 LDV.analyze(MF, LIS);1331 return LDV;1332}1333 1334PreservedAnalyses1335LiveDebugVariablesPrinterPass::run(MachineFunction &MF,1336 MachineFunctionAnalysisManager &MFAM) {1337 auto &LDV = MFAM.getResult<LiveDebugVariablesAnalysis>(MF);1338 LDV.print(OS);1339 return PreservedAnalyses::all();1340}1341 1342void LiveDebugVariables::releaseMemory() {1343 if (PImpl)1344 PImpl->clear();1345}1346 1347bool LiveDebugVariables::invalidate(1348 MachineFunction &, const PreservedAnalyses &PA,1349 MachineFunctionAnalysisManager::Invalidator &) {1350 auto PAC = PA.getChecker<LiveDebugVariablesAnalysis>();1351 // Some architectures split the register allocation into multiple phases based1352 // on register classes. This requires preserving analyses between the phases1353 // by default.1354 return !PAC.preservedWhenStateless();1355}1356 1357void LiveDebugVariables::analyze(MachineFunction &MF, LiveIntervals *LIS) {1358 if (!EnableLDV)1359 return;1360 if (!MF.getFunction().getSubprogram()) {1361 removeDebugInstrs(MF);1362 return;1363 }1364 1365 PImpl.reset(new LDVImpl(LIS));1366 1367 // Have we been asked to track variable locations using instruction1368 // referencing?1369 bool InstrRef = MF.useDebugInstrRef();1370 PImpl->runOnMachineFunction(MF, InstrRef);1371}1372 1373//===----------------------------------------------------------------------===//1374// Live Range Splitting1375//===----------------------------------------------------------------------===//1376 1377bool1378UserValue::splitLocation(unsigned OldLocNo, ArrayRef<Register> NewRegs,1379 LiveIntervals& LIS) {1380 LLVM_DEBUG({1381 dbgs() << "Splitting Loc" << OldLocNo << '\t';1382 print(dbgs(), nullptr);1383 });1384 bool DidChange = false;1385 LocMap::iterator LocMapI;1386 LocMapI.setMap(locInts);1387 for (Register NewReg : NewRegs) {1388 LiveInterval *LI = &LIS.getInterval(NewReg);1389 if (LI->empty())1390 continue;1391 1392 // Don't allocate the new LocNo until it is needed.1393 unsigned NewLocNo = UndefLocNo;1394 1395 // Iterate over the overlaps between locInts and LI.1396 LocMapI.find(LI->beginIndex());1397 if (!LocMapI.valid())1398 continue;1399 LiveInterval::iterator LII = LI->advanceTo(LI->begin(), LocMapI.start());1400 LiveInterval::iterator LIE = LI->end();1401 while (LocMapI.valid() && LII != LIE) {1402 // At this point, we know that LocMapI.stop() > LII->start.1403 LII = LI->advanceTo(LII, LocMapI.start());1404 if (LII == LIE)1405 break;1406 1407 // Now LII->end > LocMapI.start(). Do we have an overlap?1408 if (LocMapI.value().containsLocNo(OldLocNo) &&1409 LII->start < LocMapI.stop()) {1410 // Overlapping correct location. Allocate NewLocNo now.1411 if (NewLocNo == UndefLocNo) {1412 MachineOperand MO = MachineOperand::CreateReg(LI->reg(), false);1413 MO.setSubReg(locations[OldLocNo].getSubReg());1414 NewLocNo = getLocationNo(MO);1415 DidChange = true;1416 }1417 1418 SlotIndex LStart = LocMapI.start();1419 SlotIndex LStop = LocMapI.stop();1420 DbgVariableValue OldDbgValue = LocMapI.value();1421 1422 // Trim LocMapI down to the LII overlap.1423 if (LStart < LII->start)1424 LocMapI.setStartUnchecked(LII->start);1425 if (LStop > LII->end)1426 LocMapI.setStopUnchecked(LII->end);1427 1428 // Change the value in the overlap. This may trigger coalescing.1429 LocMapI.setValue(OldDbgValue.changeLocNo(OldLocNo, NewLocNo));1430 1431 // Re-insert any removed OldDbgValue ranges.1432 if (LStart < LocMapI.start()) {1433 LocMapI.insert(LStart, LocMapI.start(), OldDbgValue);1434 ++LocMapI;1435 assert(LocMapI.valid() && "Unexpected coalescing");1436 }1437 if (LStop > LocMapI.stop()) {1438 ++LocMapI;1439 LocMapI.insert(LII->end, LStop, OldDbgValue);1440 --LocMapI;1441 }1442 }1443 1444 // Advance to the next overlap.1445 if (LII->end < LocMapI.stop()) {1446 if (++LII == LIE)1447 break;1448 LocMapI.advanceTo(LII->start);1449 } else {1450 ++LocMapI;1451 if (!LocMapI.valid())1452 break;1453 LII = LI->advanceTo(LII, LocMapI.start());1454 }1455 }1456 }1457 1458 // Finally, remove OldLocNo unless it is still used by some interval in the1459 // locInts map. One case when OldLocNo still is in use is when the register1460 // has been spilled. In such situations the spilled register is kept as a1461 // location until rewriteLocations is called (VirtRegMap is mapping the old1462 // register to the spill slot). So for a while we can have locations that map1463 // to virtual registers that have been removed from both the MachineFunction1464 // and from LiveIntervals.1465 //1466 // We may also just be using the location for a value with a different1467 // expression.1468 removeLocationIfUnused(OldLocNo);1469 1470 LLVM_DEBUG({1471 dbgs() << "Split result: \t";1472 print(dbgs(), nullptr);1473 });1474 return DidChange;1475}1476 1477bool1478UserValue::splitRegister(Register OldReg, ArrayRef<Register> NewRegs,1479 LiveIntervals &LIS) {1480 bool DidChange = false;1481 // Split locations referring to OldReg. Iterate backwards so splitLocation can1482 // safely erase unused locations.1483 for (unsigned i = locations.size(); i ; --i) {1484 unsigned LocNo = i-1;1485 const MachineOperand *Loc = &locations[LocNo];1486 if (!Loc->isReg() || Loc->getReg() != OldReg)1487 continue;1488 DidChange |= splitLocation(LocNo, NewRegs, LIS);1489 }1490 return DidChange;1491}1492 1493void LiveDebugVariables::LDVImpl::splitPHIRegister(Register OldReg,1494 ArrayRef<Register> NewRegs) {1495 auto RegIt = RegToPHIIdx.find(OldReg);1496 if (RegIt == RegToPHIIdx.end())1497 return;1498 1499 std::vector<std::pair<Register, unsigned>> NewRegIdxes;1500 // Iterate over all the debug instruction numbers affected by this split.1501 for (unsigned InstrID : RegIt->second) {1502 auto PHIIt = PHIValToPos.find(InstrID);1503 assert(PHIIt != PHIValToPos.end());1504 const SlotIndex &Slot = PHIIt->second.SI;1505 assert(OldReg == PHIIt->second.Reg);1506 1507 // Find the new register that covers this position.1508 for (auto NewReg : NewRegs) {1509 const LiveInterval &LI = LIS->getInterval(NewReg);1510 auto LII = LI.find(Slot);1511 if (LII != LI.end() && LII->start <= Slot) {1512 // This new register covers this PHI position, record this for indexing.1513 NewRegIdxes.push_back(std::make_pair(NewReg, InstrID));1514 // Record that this value lives in a different VReg now.1515 PHIIt->second.Reg = NewReg;1516 break;1517 }1518 }1519 1520 // If we do not find a new register covering this PHI, then register1521 // allocation has dropped its location, for example because it's not live.1522 // The old VReg will not be mapped to a physreg, and the instruction1523 // number will have been optimized out.1524 }1525 1526 // Re-create register index using the new register numbers.1527 RegToPHIIdx.erase(RegIt);1528 for (auto &RegAndInstr : NewRegIdxes)1529 RegToPHIIdx[RegAndInstr.first].push_back(RegAndInstr.second);1530}1531 1532void LiveDebugVariables::LDVImpl::splitRegister(Register OldReg,1533 ArrayRef<Register> NewRegs) {1534 // Consider whether this split range affects any PHI locations.1535 splitPHIRegister(OldReg, NewRegs);1536 1537 // Check whether any intervals mapped by a DBG_VALUE were split and need1538 // updating.1539 bool DidChange = false;1540 for (UserValue *UV = lookupVirtReg(OldReg); UV; UV = UV->getNext())1541 DidChange |= UV->splitRegister(OldReg, NewRegs, *LIS);1542 1543 if (!DidChange)1544 return;1545 1546 // Map all of the new virtual registers.1547 UserValue *UV = lookupVirtReg(OldReg);1548 for (Register NewReg : NewRegs)1549 mapVirtReg(NewReg, UV);1550}1551 1552void LiveDebugVariables::1553splitRegister(Register OldReg, ArrayRef<Register> NewRegs, LiveIntervals &LIS) {1554 if (PImpl)1555 PImpl->splitRegister(OldReg, NewRegs);1556}1557 1558void UserValue::rewriteLocations(VirtRegMap &VRM, const MachineFunction &MF,1559 const TargetInstrInfo &TII,1560 const TargetRegisterInfo &TRI,1561 SpillOffsetMap &SpillOffsets) {1562 // Build a set of new locations with new numbers so we can coalesce our1563 // IntervalMap if two vreg intervals collapse to the same physical location.1564 // Use MapVector instead of SetVector because MapVector::insert returns the1565 // position of the previously or newly inserted element. The boolean value1566 // tracks if the location was produced by a spill.1567 // FIXME: This will be problematic if we ever support direct and indirect1568 // frame index locations, i.e. expressing both variables in memory and1569 // 'int x, *px = &x'. The "spilled" bit must become part of the location.1570 MapVector<MachineOperand, std::pair<bool, unsigned>> NewLocations;1571 SmallVector<unsigned, 4> LocNoMap(locations.size());1572 for (unsigned I = 0, E = locations.size(); I != E; ++I) {1573 bool Spilled = false;1574 unsigned SpillOffset = 0;1575 MachineOperand Loc = locations[I];1576 // Only virtual registers are rewritten.1577 if (Loc.isReg() && Loc.getReg() && Loc.getReg().isVirtual()) {1578 Register VirtReg = Loc.getReg();1579 if (VRM.isAssignedReg(VirtReg) && VRM.hasPhys(VirtReg)) {1580 // This can create a %noreg operand in rare cases when the sub-register1581 // index is no longer available. That means the user value is in a1582 // non-existent sub-register, and %noreg is exactly what we want.1583 Loc.substPhysReg(VRM.getPhys(VirtReg), TRI);1584 } else if (VRM.getStackSlot(VirtReg) != VirtRegMap::NO_STACK_SLOT) {1585 // Retrieve the stack slot offset.1586 unsigned SpillSize;1587 const MachineRegisterInfo &MRI = MF.getRegInfo();1588 const TargetRegisterClass *TRC = MRI.getRegClass(VirtReg);1589 bool Success = TII.getStackSlotRange(TRC, Loc.getSubReg(), SpillSize,1590 SpillOffset, MF);1591 1592 // FIXME: Invalidate the location if the offset couldn't be calculated.1593 (void)Success;1594 1595 Loc = MachineOperand::CreateFI(VRM.getStackSlot(VirtReg));1596 Spilled = true;1597 } else {1598 Loc.setReg(0);1599 Loc.setSubReg(0);1600 }1601 }1602 1603 // Insert this location if it doesn't already exist and record a mapping1604 // from the old number to the new number.1605 auto InsertResult = NewLocations.insert({Loc, {Spilled, SpillOffset}});1606 unsigned NewLocNo = std::distance(NewLocations.begin(), InsertResult.first);1607 LocNoMap[I] = NewLocNo;1608 }1609 1610 // Rewrite the locations and record the stack slot offsets for spills.1611 locations.clear();1612 SpillOffsets.clear();1613 for (auto &Pair : NewLocations) {1614 bool Spilled;1615 unsigned SpillOffset;1616 std::tie(Spilled, SpillOffset) = Pair.second;1617 locations.push_back(Pair.first);1618 if (Spilled) {1619 unsigned NewLocNo = std::distance(&*NewLocations.begin(), &Pair);1620 SpillOffsets[NewLocNo] = SpillOffset;1621 }1622 }1623 1624 // Update the interval map, but only coalesce left, since intervals to the1625 // right use the old location numbers. This should merge two contiguous1626 // DBG_VALUE intervals with different vregs that were allocated to the same1627 // physical register.1628 for (LocMap::iterator I = locInts.begin(); I.valid(); ++I) {1629 I.setValueUnchecked(I.value().remapLocNos(LocNoMap));1630 I.setStart(I.start());1631 }1632}1633 1634/// Find an iterator for inserting a DBG_VALUE instruction.1635static MachineBasicBlock::iterator1636findInsertLocation(MachineBasicBlock *MBB, SlotIndex Idx, LiveIntervals &LIS,1637 BlockSkipInstsMap &BBSkipInstsMap) {1638 SlotIndex Start = LIS.getMBBStartIdx(MBB);1639 Idx = Idx.getBaseIndex();1640 1641 // Try to find an insert location by going backwards from Idx.1642 MachineInstr *MI;1643 while (!(MI = LIS.getInstructionFromIndex(Idx))) {1644 // We've reached the beginning of MBB.1645 if (Idx == Start) {1646 // Retrieve the last PHI/Label/Debug location found when calling1647 // SkipPHIsLabelsAndDebug last time. Start searching from there.1648 //1649 // Note the iterator kept in BBSkipInstsMap is one step back based1650 // on the iterator returned by SkipPHIsLabelsAndDebug last time.1651 // One exception is when SkipPHIsLabelsAndDebug returns MBB->begin(),1652 // BBSkipInstsMap won't save it. This is to consider the case that1653 // new instructions may be inserted at the beginning of MBB after1654 // last call of SkipPHIsLabelsAndDebug. If we save MBB->begin() in1655 // BBSkipInstsMap, after new non-phi/non-label/non-debug instructions1656 // are inserted at the beginning of the MBB, the iterator in1657 // BBSkipInstsMap won't point to the beginning of the MBB anymore.1658 // Therefore The next search in SkipPHIsLabelsAndDebug will skip those1659 // newly added instructions and that is unwanted.1660 MachineBasicBlock::iterator BeginIt;1661 auto MapIt = BBSkipInstsMap.find(MBB);1662 if (MapIt == BBSkipInstsMap.end())1663 BeginIt = MBB->begin();1664 else1665 BeginIt = std::next(MapIt->second);1666 auto I = MBB->SkipPHIsLabelsAndDebug(BeginIt);1667 if (I != BeginIt)1668 BBSkipInstsMap[MBB] = std::prev(I);1669 return I;1670 }1671 Idx = Idx.getPrevIndex();1672 }1673 1674 // Don't insert anything after the first terminator, though.1675 auto It = MI->isTerminator() ? MBB->getFirstTerminator()1676 : std::next(MachineBasicBlock::iterator(MI));1677 return skipDebugInstructionsForward(It, MBB->end());1678}1679 1680/// Find an iterator for inserting the next DBG_VALUE instruction1681/// (or end if no more insert locations found).1682static MachineBasicBlock::iterator1683findNextInsertLocation(MachineBasicBlock *MBB, MachineBasicBlock::iterator I,1684 SlotIndex StopIdx, ArrayRef<MachineOperand> LocMOs,1685 LiveIntervals &LIS, const TargetRegisterInfo &TRI) {1686 SmallVector<Register, 4> Regs;1687 for (const MachineOperand &LocMO : LocMOs)1688 if (LocMO.isReg())1689 Regs.push_back(LocMO.getReg());1690 if (Regs.empty())1691 return MBB->instr_end();1692 1693 // Find the next instruction in the MBB that define the register Reg.1694 while (I != MBB->end() && !I->isTerminator()) {1695 if (!LIS.isNotInMIMap(*I) &&1696 SlotIndex::isEarlierEqualInstr(StopIdx, LIS.getInstructionIndex(*I)))1697 break;1698 if (any_of(Regs, [&I, &TRI](Register &Reg) {1699 return I->definesRegister(Reg, &TRI);1700 }))1701 // The insert location is directly after the instruction/bundle.1702 return std::next(I);1703 ++I;1704 }1705 return MBB->end();1706}1707 1708void UserValue::insertDebugValue(MachineBasicBlock *MBB, SlotIndex StartIdx,1709 SlotIndex StopIdx, DbgVariableValue DbgValue,1710 ArrayRef<bool> LocSpills,1711 ArrayRef<unsigned> SpillOffsets,1712 LiveIntervals &LIS, const TargetInstrInfo &TII,1713 const TargetRegisterInfo &TRI,1714 BlockSkipInstsMap &BBSkipInstsMap) {1715 SlotIndex MBBEndIdx = LIS.getMBBEndIdx(&*MBB);1716 // Only search within the current MBB.1717 StopIdx = (MBBEndIdx < StopIdx) ? MBBEndIdx : StopIdx;1718 MachineBasicBlock::iterator I =1719 findInsertLocation(MBB, StartIdx, LIS, BBSkipInstsMap);1720 // Undef values don't exist in locations so create new "noreg" register MOs1721 // for them. See getLocationNo().1722 SmallVector<MachineOperand, 8> MOs;1723 if (DbgValue.isUndef()) {1724 MOs.assign(DbgValue.loc_nos().size(),1725 MachineOperand::CreateReg(1726 /* Reg */ 0, /* isDef */ false, /* isImp */ false,1727 /* isKill */ false, /* isDead */ false,1728 /* isUndef */ false, /* isEarlyClobber */ false,1729 /* SubReg */ 0, /* isDebug */ true));1730 } else {1731 for (unsigned LocNo : DbgValue.loc_nos())1732 MOs.push_back(locations[LocNo]);1733 }1734 1735 ++NumInsertedDebugValues;1736 1737 assert(cast<DILocalVariable>(Variable)1738 ->isValidLocationForIntrinsic(getDebugLoc()) &&1739 "Expected inlined-at fields to agree");1740 1741 // If the location was spilled, the new DBG_VALUE will be indirect. If the1742 // original DBG_VALUE was indirect, we need to add DW_OP_deref to indicate1743 // that the original virtual register was a pointer. Also, add the stack slot1744 // offset for the spilled register to the expression.1745 const DIExpression *Expr = DbgValue.getExpression();1746 bool IsIndirect = DbgValue.getWasIndirect();1747 bool IsList = DbgValue.getWasList();1748 for (unsigned I = 0, E = LocSpills.size(); I != E; ++I) {1749 if (LocSpills[I]) {1750 if (!IsList) {1751 uint8_t DIExprFlags = DIExpression::ApplyOffset;1752 if (IsIndirect)1753 DIExprFlags |= DIExpression::DerefAfter;1754 Expr = DIExpression::prepend(Expr, DIExprFlags, SpillOffsets[I]);1755 IsIndirect = true;1756 } else {1757 SmallVector<uint64_t, 4> Ops;1758 DIExpression::appendOffset(Ops, SpillOffsets[I]);1759 Ops.push_back(dwarf::DW_OP_deref);1760 Expr = DIExpression::appendOpsToArg(Expr, Ops, I);1761 }1762 }1763 1764 assert((!LocSpills[I] || MOs[I].isFI()) &&1765 "a spilled location must be a frame index");1766 }1767 1768 unsigned DbgValueOpcode =1769 IsList ? TargetOpcode::DBG_VALUE_LIST : TargetOpcode::DBG_VALUE;1770 do {1771 BuildMI(*MBB, I, getDebugLoc(), TII.get(DbgValueOpcode), IsIndirect, MOs,1772 Variable, Expr);1773 1774 // Continue and insert DBG_VALUES after every redefinition of a register1775 // associated with the debug value within the range1776 I = findNextInsertLocation(MBB, I, StopIdx, MOs, LIS, TRI);1777 } while (I != MBB->end());1778}1779 1780void UserLabel::insertDebugLabel(MachineBasicBlock *MBB, SlotIndex Idx,1781 LiveIntervals &LIS, const TargetInstrInfo &TII,1782 BlockSkipInstsMap &BBSkipInstsMap) {1783 MachineBasicBlock::iterator I =1784 findInsertLocation(MBB, Idx, LIS, BBSkipInstsMap);1785 ++NumInsertedDebugLabels;1786 BuildMI(*MBB, I, getDebugLoc(), TII.get(TargetOpcode::DBG_LABEL))1787 .addMetadata(Label);1788}1789 1790void UserValue::emitDebugValues(VirtRegMap *VRM, LiveIntervals &LIS,1791 const TargetInstrInfo &TII,1792 const TargetRegisterInfo &TRI,1793 const SpillOffsetMap &SpillOffsets,1794 BlockSkipInstsMap &BBSkipInstsMap) {1795 MachineFunction::iterator MFEnd = VRM->getMachineFunction().end();1796 1797 for (LocMap::const_iterator I = locInts.begin(); I.valid();) {1798 SlotIndex Start = I.start();1799 SlotIndex Stop = I.stop();1800 DbgVariableValue DbgValue = I.value();1801 1802 SmallVector<bool> SpilledLocs;1803 SmallVector<unsigned> LocSpillOffsets;1804 for (unsigned LocNo : DbgValue.loc_nos()) {1805 auto SpillIt =1806 !DbgValue.isUndef() ? SpillOffsets.find(LocNo) : SpillOffsets.end();1807 bool Spilled = SpillIt != SpillOffsets.end();1808 SpilledLocs.push_back(Spilled);1809 LocSpillOffsets.push_back(Spilled ? SpillIt->second : 0);1810 }1811 1812 // If the interval start was trimmed to the lexical scope insert the1813 // DBG_VALUE at the previous index (otherwise it appears after the1814 // first instruction in the range).1815 if (trimmedDefs.count(Start))1816 Start = Start.getPrevIndex();1817 1818 LLVM_DEBUG(auto &dbg = dbgs(); dbg << "\t[" << Start << ';' << Stop << "):";1819 DbgValue.printLocNos(dbg));1820 MachineFunction::iterator MBB = LIS.getMBBFromIndex(Start)->getIterator();1821 SlotIndex MBBEnd = LIS.getMBBEndIdx(&*MBB);1822 1823 LLVM_DEBUG(dbgs() << ' ' << printMBBReference(*MBB) << '-' << MBBEnd);1824 insertDebugValue(&*MBB, Start, Stop, DbgValue, SpilledLocs, LocSpillOffsets,1825 LIS, TII, TRI, BBSkipInstsMap);1826 // This interval may span multiple basic blocks.1827 // Insert a DBG_VALUE into each one.1828 while (Stop > MBBEnd) {1829 // Move to the next block.1830 Start = MBBEnd;1831 if (++MBB == MFEnd)1832 break;1833 MBBEnd = LIS.getMBBEndIdx(&*MBB);1834 LLVM_DEBUG(dbgs() << ' ' << printMBBReference(*MBB) << '-' << MBBEnd);1835 insertDebugValue(&*MBB, Start, Stop, DbgValue, SpilledLocs,1836 LocSpillOffsets, LIS, TII, TRI, BBSkipInstsMap);1837 }1838 LLVM_DEBUG(dbgs() << '\n');1839 if (MBB == MFEnd)1840 break;1841 1842 ++I;1843 }1844}1845 1846void UserLabel::emitDebugLabel(LiveIntervals &LIS, const TargetInstrInfo &TII,1847 BlockSkipInstsMap &BBSkipInstsMap) {1848 LLVM_DEBUG(dbgs() << "\t" << loc);1849 MachineFunction::iterator MBB = LIS.getMBBFromIndex(loc)->getIterator();1850 1851 LLVM_DEBUG(dbgs() << ' ' << printMBBReference(*MBB));1852 insertDebugLabel(&*MBB, loc, LIS, TII, BBSkipInstsMap);1853 1854 LLVM_DEBUG(dbgs() << '\n');1855}1856 1857void LiveDebugVariables::LDVImpl::emitDebugValues(VirtRegMap *VRM) {1858 LLVM_DEBUG(dbgs() << "********** EMITTING LIVE DEBUG VARIABLES **********\n");1859 if (!MF)1860 return;1861 1862 BlockSkipInstsMap BBSkipInstsMap;1863 const TargetInstrInfo *TII = MF->getSubtarget().getInstrInfo();1864 SpillOffsetMap SpillOffsets;1865 for (auto &userValue : userValues) {1866 LLVM_DEBUG(userValue->print(dbgs(), TRI));1867 userValue->rewriteLocations(*VRM, *MF, *TII, *TRI, SpillOffsets);1868 userValue->emitDebugValues(VRM, *LIS, *TII, *TRI, SpillOffsets,1869 BBSkipInstsMap);1870 }1871 LLVM_DEBUG(dbgs() << "********** EMITTING LIVE DEBUG LABELS **********\n");1872 for (auto &userLabel : userLabels) {1873 LLVM_DEBUG(userLabel->print(dbgs(), TRI));1874 userLabel->emitDebugLabel(*LIS, *TII, BBSkipInstsMap);1875 }1876 1877 LLVM_DEBUG(dbgs() << "********** EMITTING DEBUG PHIS **********\n");1878 1879 auto Slots = LIS->getSlotIndexes();1880 for (auto &It : PHIValToPos) {1881 // For each ex-PHI, identify its physreg location or stack slot, and emit1882 // a DBG_PHI for it.1883 unsigned InstNum = It.first;1884 auto Slot = It.second.SI;1885 Register Reg = It.second.Reg;1886 unsigned SubReg = It.second.SubReg;1887 1888 MachineBasicBlock *OrigMBB = Slots->getMBBFromIndex(Slot);1889 if (VRM->isAssignedReg(Reg) && VRM->hasPhys(Reg)) {1890 unsigned PhysReg = VRM->getPhys(Reg);1891 if (SubReg != 0)1892 PhysReg = TRI->getSubReg(PhysReg, SubReg);1893 1894 auto Builder = BuildMI(*OrigMBB, OrigMBB->begin(), DebugLoc(),1895 TII->get(TargetOpcode::DBG_PHI));1896 Builder.addReg(PhysReg);1897 Builder.addImm(InstNum);1898 } else if (VRM->getStackSlot(Reg) != VirtRegMap::NO_STACK_SLOT) {1899 const MachineRegisterInfo &MRI = MF->getRegInfo();1900 const TargetRegisterClass *TRC = MRI.getRegClass(Reg);1901 unsigned SpillSize, SpillOffset;1902 1903 unsigned regSizeInBits = TRI->getRegSizeInBits(*TRC);1904 if (SubReg)1905 regSizeInBits = TRI->getSubRegIdxSize(SubReg);1906 1907 // Test whether this location is legal with the given subreg. If the1908 // subregister has a nonzero offset, drop this location, it's too complex1909 // to describe. (TODO: future work).1910 bool Success =1911 TII->getStackSlotRange(TRC, SubReg, SpillSize, SpillOffset, *MF);1912 1913 if (Success && SpillOffset == 0) {1914 auto Builder = BuildMI(*OrigMBB, OrigMBB->begin(), DebugLoc(),1915 TII->get(TargetOpcode::DBG_PHI));1916 Builder.addFrameIndex(VRM->getStackSlot(Reg));1917 Builder.addImm(InstNum);1918 // Record how large the original value is. The stack slot might be1919 // merged and altered during optimisation, but we will want to know how1920 // large the value is, at this DBG_PHI.1921 Builder.addImm(regSizeInBits);1922 }1923 1924 LLVM_DEBUG(if (SpillOffset != 0) {1925 dbgs() << "DBG_PHI for " << printReg(Reg, TRI, SubReg)1926 << " has nonzero offset\n";1927 });1928 }1929 // If there was no mapping for a value ID, it's optimized out. Create no1930 // DBG_PHI, and any variables using this value will become optimized out.1931 }1932 MF->DebugPHIPositions.clear();1933 1934 LLVM_DEBUG(dbgs() << "********** EMITTING INSTR REFERENCES **********\n");1935 1936 // Re-insert any debug instrs back in the position they were. We must1937 // re-insert in the same order to ensure that debug instructions don't swap,1938 // which could re-order assignments. Do so in a batch -- once we find the1939 // insert position, insert all instructions at the same SlotIdx. They are1940 // guaranteed to appear in-sequence in StashedDebugInstrs because we insert1941 // them in order.1942 for (auto *StashIt = StashedDebugInstrs.begin();1943 StashIt != StashedDebugInstrs.end(); ++StashIt) {1944 SlotIndex Idx = StashIt->Idx;1945 MachineBasicBlock *MBB = StashIt->MBB;1946 MachineInstr *MI = StashIt->MI;1947 1948 auto EmitInstsHere = [this, &StashIt, MBB, Idx,1949 MI](MachineBasicBlock::iterator InsertPos) {1950 // Insert this debug instruction.1951 MBB->insert(InsertPos, MI);1952 1953 // Look at subsequent stashed debug instructions: if they're at the same1954 // index, insert those too.1955 auto NextItem = std::next(StashIt);1956 while (NextItem != StashedDebugInstrs.end() && NextItem->Idx == Idx) {1957 assert(NextItem->MBB == MBB && "Instrs with same slot index should be"1958 "in the same block");1959 MBB->insert(InsertPos, NextItem->MI);1960 StashIt = NextItem;1961 NextItem = std::next(StashIt);1962 };1963 };1964 1965 // Start block index: find the first non-debug instr in the block, and1966 // insert before it.1967 if (Idx == Slots->getMBBStartIdx(MBB)) {1968 MachineBasicBlock::iterator InsertPos =1969 findInsertLocation(MBB, Idx, *LIS, BBSkipInstsMap);1970 EmitInstsHere(InsertPos);1971 continue;1972 }1973 1974 if (MachineInstr *Pos = Slots->getInstructionFromIndex(Idx)) {1975 // Insert at the end of any debug instructions.1976 auto PostDebug = std::next(MachineBasicBlock::iterator(Pos));1977 PostDebug = skipDebugInstructionsForward(PostDebug, MBB->end());1978 EmitInstsHere(PostDebug);1979 } else {1980 // Insert position disappeared; walk forwards through slots until we1981 // find a new one.1982 SlotIndex End = Slots->getMBBEndIdx(MBB);1983 for (; Idx < End; Idx = Slots->getNextNonNullIndex(Idx)) {1984 Pos = Slots->getInstructionFromIndex(Idx);1985 if (Pos) {1986 EmitInstsHere(Pos->getIterator());1987 break;1988 }1989 }1990 1991 // We have reached the end of the block and didn't find anywhere to1992 // insert! It's not safe to discard any debug instructions; place them1993 // in front of the first terminator, or in front of end().1994 if (Idx >= End) {1995 auto TermIt = MBB->getFirstTerminator();1996 EmitInstsHere(TermIt);1997 }1998 }1999 }2000 2001 EmitDone = true;2002 BBSkipInstsMap.clear();2003}2004 2005void LiveDebugVariables::emitDebugValues(VirtRegMap *VRM) {2006 if (PImpl)2007 PImpl->emitDebugValues(VRM);2008}2009 2010#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)2011LLVM_DUMP_METHOD void LiveDebugVariables::dump() const { print(dbgs()); }2012#endif2013 2014void LiveDebugVariables::print(raw_ostream &OS) const {2015 if (PImpl)2016 PImpl->print(OS);2017}2018