LLVM 19.0.0git
AssignmentTrackingAnalysis.cpp
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1//===-- AssignmentTrackingAnalysis.cpp ------------------------------------===//
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
11#include "llvm/ADT/BitVector.h"
15#include "llvm/ADT/STLExtras.h"
16#include "llvm/ADT/Statistic.h"
19#include "llvm/IR/BasicBlock.h"
20#include "llvm/IR/DataLayout.h"
21#include "llvm/IR/DebugInfo.h"
23#include "llvm/IR/Function.h"
24#include "llvm/IR/Instruction.h"
26#include "llvm/IR/Module.h"
27#include "llvm/IR/PassManager.h"
28#include "llvm/IR/PrintPasses.h"
34#include <assert.h>
35#include <cstdint>
36#include <optional>
37#include <queue>
38#include <sstream>
39#include <unordered_map>
40
41using namespace llvm;
42#define DEBUG_TYPE "debug-ata"
43
44STATISTIC(NumDefsScanned, "Number of dbg locs that get scanned for removal");
45STATISTIC(NumDefsRemoved, "Number of dbg locs removed");
46STATISTIC(NumWedgesScanned, "Number of dbg wedges scanned");
47STATISTIC(NumWedgesChanged, "Number of dbg wedges changed");
48
50 MaxNumBlocks("debug-ata-max-blocks", cl::init(10000),
51 cl::desc("Maximum num basic blocks before debug info dropped"),
53/// Option for debugging the pass, determines if the memory location fragment
54/// filling happens after generating the variable locations.
55static cl::opt<bool> EnableMemLocFragFill("mem-loc-frag-fill", cl::init(true),
57/// Print the results of the analysis. Respects -filter-print-funcs.
58static cl::opt<bool> PrintResults("print-debug-ata", cl::init(false),
60
61/// Coalesce adjacent dbg locs describing memory locations that have contiguous
62/// fragments. This reduces the cost of LiveDebugValues which does SSA
63/// construction for each explicitly stated variable fragment.
65 CoalesceAdjacentFragmentsOpt("debug-ata-coalesce-frags", cl::Hidden);
66
67// Implicit conversions are disabled for enum class types, so unfortunately we
68// need to create a DenseMapInfo wrapper around the specified underlying type.
69template <> struct llvm::DenseMapInfo<VariableID> {
71 static inline VariableID getEmptyKey() {
72 return static_cast<VariableID>(Wrapped::getEmptyKey());
73 }
74 static inline VariableID getTombstoneKey() {
75 return static_cast<VariableID>(Wrapped::getTombstoneKey());
76 }
77 static unsigned getHashValue(const VariableID &Val) {
78 return Wrapped::getHashValue(static_cast<unsigned>(Val));
79 }
80 static bool isEqual(const VariableID &LHS, const VariableID &RHS) {
81 return LHS == RHS;
82 }
83};
84
86
87namespace std {
88template <> struct hash<VarLocInsertPt> {
90 using result_type = std::size_t;
91
93 return std::hash<void *>()(Arg.getOpaqueValue());
94 }
95};
96} // namespace std
97
98/// Helper class to build FunctionVarLocs, since that class isn't easy to
99/// modify. TODO: There's not a great deal of value in the split, it could be
100/// worth merging the two classes.
102 friend FunctionVarLocs;
104 // Use an unordered_map so we don't invalidate iterators after
105 // insert/modifications.
106 std::unordered_map<VarLocInsertPt, SmallVector<VarLocInfo>> VarLocsBeforeInst;
107
108 SmallVector<VarLocInfo> SingleLocVars;
109
110public:
111 unsigned getNumVariables() const { return Variables.size(); }
112
113 /// Find or insert \p V and return the ID.
115 return static_cast<VariableID>(Variables.insert(V));
116 }
117
118 /// Get a variable from its \p ID.
120 return Variables[static_cast<unsigned>(ID)];
121 }
122
123 /// Return ptr to wedge of defs or nullptr if no defs come just before /p
124 /// Before.
126 auto R = VarLocsBeforeInst.find(Before);
127 if (R == VarLocsBeforeInst.end())
128 return nullptr;
129 return &R->second;
130 }
131
132 /// Replace the defs that come just before /p Before with /p Wedge.
134 VarLocsBeforeInst[Before] = std::move(Wedge);
135 }
136
137 /// Add a def for a variable that is valid for its lifetime.
140 VarLocInfo VarLoc;
141 VarLoc.VariableID = insertVariable(Var);
142 VarLoc.Expr = Expr;
143 VarLoc.DL = DL;
144 VarLoc.Values = R;
145 SingleLocVars.emplace_back(VarLoc);
146 }
147
148 /// Add a def to the wedge of defs just before /p Before.
151 VarLocInfo VarLoc;
152 VarLoc.VariableID = insertVariable(Var);
153 VarLoc.Expr = Expr;
154 VarLoc.DL = DL;
155 VarLoc.Values = R;
156 VarLocsBeforeInst[Before].emplace_back(VarLoc);
157 }
158};
159
161 // Print the variable table first. TODO: Sorting by variable could make the
162 // output more stable?
163 unsigned Counter = -1;
164 OS << "=== Variables ===\n";
165 for (const DebugVariable &V : Variables) {
166 ++Counter;
167 // Skip first entry because it is a dummy entry.
168 if (Counter == 0) {
169 continue;
170 }
171 OS << "[" << Counter << "] " << V.getVariable()->getName();
172 if (auto F = V.getFragment())
173 OS << " bits [" << F->OffsetInBits << ", "
174 << F->OffsetInBits + F->SizeInBits << ")";
175 if (const auto *IA = V.getInlinedAt())
176 OS << " inlined-at " << *IA;
177 OS << "\n";
178 }
179
180 auto PrintLoc = [&OS](const VarLocInfo &Loc) {
181 OS << "DEF Var=[" << (unsigned)Loc.VariableID << "]"
182 << " Expr=" << *Loc.Expr << " Values=(";
183 for (auto *Op : Loc.Values.location_ops()) {
184 errs() << Op->getName() << " ";
185 }
186 errs() << ")\n";
187 };
188
189 // Print the single location variables.
190 OS << "=== Single location vars ===\n";
191 for (auto It = single_locs_begin(), End = single_locs_end(); It != End;
192 ++It) {
193 PrintLoc(*It);
194 }
195
196 // Print the non-single-location defs in line with IR.
197 OS << "=== In-line variable defs ===";
198 for (const BasicBlock &BB : Fn) {
199 OS << "\n" << BB.getName() << ":\n";
200 for (const Instruction &I : BB) {
201 for (auto It = locs_begin(&I), End = locs_end(&I); It != End; ++It) {
202 PrintLoc(*It);
203 }
204 OS << I << "\n";
205 }
206 }
207}
208
210 // Add the single-location variables first.
211 for (const auto &VarLoc : Builder.SingleLocVars)
212 VarLocRecords.emplace_back(VarLoc);
213 // Mark the end of the section.
214 SingleVarLocEnd = VarLocRecords.size();
215
216 // Insert a contiguous block of VarLocInfos for each instruction, mapping it
217 // to the start and end position in the vector with VarLocsBeforeInst. This
218 // block includes VarLocs for any DbgVariableRecords attached to that
219 // instruction.
220 for (auto &P : Builder.VarLocsBeforeInst) {
221 // Process VarLocs attached to a DbgRecord alongside their marker
222 // Instruction.
223 if (isa<const DbgRecord *>(P.first))
224 continue;
225 const Instruction *I = cast<const Instruction *>(P.first);
226 unsigned BlockStart = VarLocRecords.size();
227 // Any VarLocInfos attached to a DbgRecord should now be remapped to their
228 // marker Instruction, in order of DbgRecord appearance and prior to any
229 // VarLocInfos attached directly to that instruction.
230 for (const DbgVariableRecord &DVR : filterDbgVars(I->getDbgRecordRange())) {
231 // Even though DVR defines a variable location, VarLocsBeforeInst can
232 // still be empty if that VarLoc was redundant.
233 if (!Builder.VarLocsBeforeInst.count(&DVR))
234 continue;
235 for (const VarLocInfo &VarLoc : Builder.VarLocsBeforeInst[&DVR])
236 VarLocRecords.emplace_back(VarLoc);
237 }
238 for (const VarLocInfo &VarLoc : P.second)
239 VarLocRecords.emplace_back(VarLoc);
240 unsigned BlockEnd = VarLocRecords.size();
241 // Record the start and end indices.
242 if (BlockEnd != BlockStart)
243 VarLocsBeforeInst[I] = {BlockStart, BlockEnd};
244 }
245
246 // Copy the Variables vector from the builder's UniqueVector.
247 assert(Variables.empty() && "Expect clear before init");
248 // UniqueVectors IDs are one-based (which means the VarLocInfo VarID values
249 // are one-based) so reserve an extra and insert a dummy.
250 Variables.reserve(Builder.Variables.size() + 1);
251 Variables.push_back(DebugVariable(nullptr, std::nullopt, nullptr));
252 Variables.append(Builder.Variables.begin(), Builder.Variables.end());
253}
254
256 Variables.clear();
257 VarLocRecords.clear();
258 VarLocsBeforeInst.clear();
259 SingleVarLocEnd = 0;
260}
261
262/// Walk backwards along constant GEPs and bitcasts to the base storage from \p
263/// Start as far as possible. Prepend \Expression with the offset and append it
264/// with a DW_OP_deref that haes been implicit until now. Returns the walked-to
265/// value and modified expression.
266static std::pair<Value *, DIExpression *>
269 APInt OffsetInBytes(DL.getTypeSizeInBits(Start->getType()), false);
270 Value *End =
271 Start->stripAndAccumulateInBoundsConstantOffsets(DL, OffsetInBytes);
273 if (OffsetInBytes.getBoolValue()) {
274 Ops = {dwarf::DW_OP_plus_uconst, OffsetInBytes.getZExtValue()};
276 Expression, Ops, /*StackValue=*/false, /*EntryValue=*/false);
277 }
278 Expression = DIExpression::append(Expression, {dwarf::DW_OP_deref});
279 return {End, Expression};
280}
281
282/// Extract the offset used in \p DIExpr. Returns std::nullopt if the expression
283/// doesn't explicitly describe a memory location with DW_OP_deref or if the
284/// expression is too complex to interpret.
285static std::optional<int64_t>
287 int64_t Offset = 0;
288 const unsigned NumElements = DIExpr->getNumElements();
289 const auto Elements = DIExpr->getElements();
290 unsigned ExpectedDerefIdx = 0;
291 // Extract the offset.
292 if (NumElements > 2 && Elements[0] == dwarf::DW_OP_plus_uconst) {
293 Offset = Elements[1];
294 ExpectedDerefIdx = 2;
295 } else if (NumElements > 3 && Elements[0] == dwarf::DW_OP_constu) {
296 ExpectedDerefIdx = 3;
297 if (Elements[2] == dwarf::DW_OP_plus)
298 Offset = Elements[1];
299 else if (Elements[2] == dwarf::DW_OP_minus)
300 Offset = -Elements[1];
301 else
302 return std::nullopt;
303 }
304
305 // If that's all there is it means there's no deref.
306 if (ExpectedDerefIdx >= NumElements)
307 return std::nullopt;
308
309 // Check the next element is DW_OP_deref - otherwise this is too complex or
310 // isn't a deref expression.
311 if (Elements[ExpectedDerefIdx] != dwarf::DW_OP_deref)
312 return std::nullopt;
313
314 // Check the final operation is either the DW_OP_deref or is a fragment.
315 if (NumElements == ExpectedDerefIdx + 1)
316 return Offset; // Ends with deref.
317 unsigned ExpectedFragFirstIdx = ExpectedDerefIdx + 1;
318 unsigned ExpectedFragFinalIdx = ExpectedFragFirstIdx + 2;
319 if (NumElements == ExpectedFragFinalIdx + 1 &&
320 Elements[ExpectedFragFirstIdx] == dwarf::DW_OP_LLVM_fragment)
321 return Offset; // Ends with deref + fragment.
322
323 // Don't bother trying to interpret anything more complex.
324 return std::nullopt;
325}
326
327/// A whole (unfragmented) source variable.
328using DebugAggregate = std::pair<const DILocalVariable *, const DILocation *>;
330 return DebugAggregate(DII->getVariable(), DII->getDebugLoc().getInlinedAt());
331}
333 return DebugAggregate(Var.getVariable(), Var.getInlinedAt());
334}
335
337 // Enabling fragment coalescing reduces compiler run time when instruction
338 // referencing is enabled. However, it may cause LiveDebugVariables to create
339 // incorrect locations. Since instruction-referencing mode effectively
340 // bypasses LiveDebugVariables we only enable coalescing if the cl::opt flag
341 // has not been explicitly set and instruction-referencing is turned on.
345 Triple(F.getParent()->getTargetTriple()));
347 return true;
349 return false;
350 }
351 llvm_unreachable("Unknown boolOrDefault value");
352}
353
354namespace {
355/// In dwarf emission, the following sequence
356/// 1. dbg.value ... Fragment(0, 64)
357/// 2. dbg.value ... Fragment(0, 32)
358/// effectively sets Fragment(32, 32) to undef (each def sets all bits not in
359/// the intersection of the fragments to having "no location"). This makes
360/// sense for implicit location values because splitting the computed values
361/// could be troublesome, and is probably quite uncommon. When we convert
362/// dbg.assigns to dbg.value+deref this kind of thing is common, and describing
363/// a location (memory) rather than a value means we don't need to worry about
364/// splitting any values, so we try to recover the rest of the fragment
365/// location here.
366/// This class performs a(nother) dataflow analysis over the function, adding
367/// variable locations so that any bits of a variable with a memory location
368/// have that location explicitly reinstated at each subsequent variable
369/// location definition that that doesn't overwrite those bits. i.e. after a
370/// variable location def, insert new defs for the memory location with
371/// fragments for the difference of "all bits currently in memory" and "the
372/// fragment of the second def".
373class MemLocFragmentFill {
374 Function &Fn;
375 FunctionVarLocsBuilder *FnVarLocs;
376 const DenseSet<DebugAggregate> *VarsWithStackSlot;
377 bool CoalesceAdjacentFragments;
378
379 // 0 = no memory location.
380 using BaseAddress = unsigned;
381 using OffsetInBitsTy = unsigned;
383 using FragsInMemMap = IntervalMap<
384 OffsetInBitsTy, BaseAddress,
386 FragTraits>;
387 FragsInMemMap::Allocator IntervalMapAlloc;
388 using VarFragMap = DenseMap<unsigned, FragsInMemMap>;
389
390 /// IDs for memory location base addresses in maps. Use 0 to indicate that
391 /// there's no memory location.
396
397 struct FragMemLoc {
398 unsigned Var;
399 unsigned Base;
400 unsigned OffsetInBits;
401 unsigned SizeInBits;
402 DebugLoc DL;
403 };
405
406 /// BBInsertBeforeMap holds a description for the set of location defs to be
407 /// inserted after the analysis is complete. It is updated during the dataflow
408 /// and the entry for a block is CLEARED each time it is (re-)visited. After
409 /// the dataflow is complete, each block entry will contain the set of defs
410 /// calculated during the final (fixed-point) iteration.
412
413 static bool intervalMapsAreEqual(const FragsInMemMap &A,
414 const FragsInMemMap &B) {
415 auto AIt = A.begin(), AEnd = A.end();
416 auto BIt = B.begin(), BEnd = B.end();
417 for (; AIt != AEnd; ++AIt, ++BIt) {
418 if (BIt == BEnd)
419 return false; // B has fewer elements than A.
420 if (AIt.start() != BIt.start() || AIt.stop() != BIt.stop())
421 return false; // Interval is different.
422 if (*AIt != *BIt)
423 return false; // Value at interval is different.
424 }
425 // AIt == AEnd. Check BIt is also now at end.
426 return BIt == BEnd;
427 }
428
429 static bool varFragMapsAreEqual(const VarFragMap &A, const VarFragMap &B) {
430 if (A.size() != B.size())
431 return false;
432 for (const auto &APair : A) {
433 auto BIt = B.find(APair.first);
434 if (BIt == B.end())
435 return false;
436 if (!intervalMapsAreEqual(APair.second, BIt->second))
437 return false;
438 }
439 return true;
440 }
441
442 /// Return a string for the value that \p BaseID represents.
443 std::string toString(unsigned BaseID) {
444 if (BaseID)
445 return Bases[BaseID].getVariableLocationOp(0)->getName().str();
446 else
447 return "None";
448 }
449
450 /// Format string describing an FragsInMemMap (IntervalMap) interval.
451 std::string toString(FragsInMemMap::const_iterator It, bool Newline = true) {
452 std::string String;
453 std::stringstream S(String);
454 if (It.valid()) {
455 S << "[" << It.start() << ", " << It.stop()
456 << "): " << toString(It.value());
457 } else {
458 S << "invalid iterator (end)";
459 }
460 if (Newline)
461 S << "\n";
462 return S.str();
463 };
464
465 FragsInMemMap meetFragments(const FragsInMemMap &A, const FragsInMemMap &B) {
466 FragsInMemMap Result(IntervalMapAlloc);
467 for (auto AIt = A.begin(), AEnd = A.end(); AIt != AEnd; ++AIt) {
468 LLVM_DEBUG(dbgs() << "a " << toString(AIt));
469 // This is basically copied from process() and inverted (process is
470 // performing something like a union whereas this is more of an
471 // intersect).
472
473 // There's no work to do if interval `a` overlaps no fragments in map `B`.
474 if (!B.overlaps(AIt.start(), AIt.stop()))
475 continue;
476
477 // Does StartBit intersect an existing fragment?
478 auto FirstOverlap = B.find(AIt.start());
479 assert(FirstOverlap != B.end());
480 bool IntersectStart = FirstOverlap.start() < AIt.start();
481 LLVM_DEBUG(dbgs() << "- FirstOverlap " << toString(FirstOverlap, false)
482 << ", IntersectStart: " << IntersectStart << "\n");
483
484 // Does EndBit intersect an existing fragment?
485 auto LastOverlap = B.find(AIt.stop());
486 bool IntersectEnd =
487 LastOverlap != B.end() && LastOverlap.start() < AIt.stop();
488 LLVM_DEBUG(dbgs() << "- LastOverlap " << toString(LastOverlap, false)
489 << ", IntersectEnd: " << IntersectEnd << "\n");
490
491 // Check if both ends of `a` intersect the same interval `b`.
492 if (IntersectStart && IntersectEnd && FirstOverlap == LastOverlap) {
493 // Insert `a` (`a` is contained in `b`) if the values match.
494 // [ a ]
495 // [ - b - ]
496 // -
497 // [ r ]
498 LLVM_DEBUG(dbgs() << "- a is contained within "
499 << toString(FirstOverlap));
500 if (*AIt && *AIt == *FirstOverlap)
501 Result.insert(AIt.start(), AIt.stop(), *AIt);
502 } else {
503 // There's an overlap but `a` is not fully contained within
504 // `b`. Shorten any end-point intersections.
505 // [ - a - ]
506 // [ - b - ]
507 // -
508 // [ r ]
509 auto Next = FirstOverlap;
510 if (IntersectStart) {
511 LLVM_DEBUG(dbgs() << "- insert intersection of a and "
512 << toString(FirstOverlap));
513 if (*AIt && *AIt == *FirstOverlap)
514 Result.insert(AIt.start(), FirstOverlap.stop(), *AIt);
515 ++Next;
516 }
517 // [ - a - ]
518 // [ - b - ]
519 // -
520 // [ r ]
521 if (IntersectEnd) {
522 LLVM_DEBUG(dbgs() << "- insert intersection of a and "
523 << toString(LastOverlap));
524 if (*AIt && *AIt == *LastOverlap)
525 Result.insert(LastOverlap.start(), AIt.stop(), *AIt);
526 }
527
528 // Insert all intervals in map `B` that are contained within interval
529 // `a` where the values match.
530 // [ - - a - - ]
531 // [ b1 ] [ b2 ]
532 // -
533 // [ r1 ] [ r2 ]
534 while (Next != B.end() && Next.start() < AIt.stop() &&
535 Next.stop() <= AIt.stop()) {
537 << "- insert intersection of a and " << toString(Next));
538 if (*AIt && *AIt == *Next)
539 Result.insert(Next.start(), Next.stop(), *Next);
540 ++Next;
541 }
542 }
543 }
544 return Result;
545 }
546
547 /// Meet \p A and \p B, storing the result in \p A.
548 void meetVars(VarFragMap &A, const VarFragMap &B) {
549 // Meet A and B.
550 //
551 // Result = meet(a, b) for a in A, b in B where Var(a) == Var(b)
552 for (auto It = A.begin(), End = A.end(); It != End; ++It) {
553 unsigned AVar = It->first;
554 FragsInMemMap &AFrags = It->second;
555 auto BIt = B.find(AVar);
556 if (BIt == B.end()) {
557 A.erase(It);
558 continue; // Var has no bits defined in B.
559 }
560 LLVM_DEBUG(dbgs() << "meet fragment maps for "
561 << Aggregates[AVar].first->getName() << "\n");
562 AFrags = meetFragments(AFrags, BIt->second);
563 }
564 }
565
566 bool meet(const BasicBlock &BB,
567 const SmallPtrSet<BasicBlock *, 16> &Visited) {
568 LLVM_DEBUG(dbgs() << "meet block info from preds of " << BB.getName()
569 << "\n");
570
571 VarFragMap BBLiveIn;
572 bool FirstMeet = true;
573 // LiveIn locs for BB is the meet of the already-processed preds' LiveOut
574 // locs.
575 for (const BasicBlock *Pred : predecessors(&BB)) {
576 // Ignore preds that haven't been processed yet. This is essentially the
577 // same as initialising all variables to implicit top value (⊤) which is
578 // the identity value for the meet operation.
579 if (!Visited.count(Pred))
580 continue;
581
582 auto PredLiveOut = LiveOut.find(Pred);
583 assert(PredLiveOut != LiveOut.end());
584
585 if (FirstMeet) {
586 LLVM_DEBUG(dbgs() << "BBLiveIn = " << Pred->getName() << "\n");
587 BBLiveIn = PredLiveOut->second;
588 FirstMeet = false;
589 } else {
590 LLVM_DEBUG(dbgs() << "BBLiveIn = meet BBLiveIn, " << Pred->getName()
591 << "\n");
592 meetVars(BBLiveIn, PredLiveOut->second);
593 }
594
595 // An empty set is ⊥ for the intersect-like meet operation. If we've
596 // already got ⊥ there's no need to run the code - we know the result is
597 // ⊥ since `meet(a, ⊥) = ⊥`.
598 if (BBLiveIn.size() == 0)
599 break;
600 }
601
602 auto CurrentLiveInEntry = LiveIn.find(&BB);
603 // If there's no LiveIn entry for the block yet, add it.
604 if (CurrentLiveInEntry == LiveIn.end()) {
605 LLVM_DEBUG(dbgs() << "change=true (first) on meet on " << BB.getName()
606 << "\n");
607 LiveIn[&BB] = std::move(BBLiveIn);
608 return /*Changed=*/true;
609 }
610
611 // If the LiveIn set has changed (expensive check) update it and return
612 // true.
613 if (!varFragMapsAreEqual(BBLiveIn, CurrentLiveInEntry->second)) {
614 LLVM_DEBUG(dbgs() << "change=true on meet on " << BB.getName() << "\n");
615 CurrentLiveInEntry->second = std::move(BBLiveIn);
616 return /*Changed=*/true;
617 }
618
619 LLVM_DEBUG(dbgs() << "change=false on meet on " << BB.getName() << "\n");
620 return /*Changed=*/false;
621 }
622
623 void insertMemLoc(BasicBlock &BB, VarLocInsertPt Before, unsigned Var,
624 unsigned StartBit, unsigned EndBit, unsigned Base,
625 DebugLoc DL) {
626 assert(StartBit < EndBit && "Cannot create fragment of size <= 0");
627 if (!Base)
628 return;
629 FragMemLoc Loc;
630 Loc.Var = Var;
631 Loc.OffsetInBits = StartBit;
632 Loc.SizeInBits = EndBit - StartBit;
633 assert(Base && "Expected a non-zero ID for Base address");
634 Loc.Base = Base;
635 Loc.DL = DL;
636 BBInsertBeforeMap[&BB][Before].push_back(Loc);
637 LLVM_DEBUG(dbgs() << "Add mem def for " << Aggregates[Var].first->getName()
638 << " bits [" << StartBit << ", " << EndBit << ")\n");
639 }
640
641 /// Inserts a new dbg def if the interval found when looking up \p StartBit
642 /// in \p FragMap starts before \p StartBit or ends after \p EndBit (which
643 /// indicates - assuming StartBit->EndBit has just been inserted - that the
644 /// slice has been coalesced in the map).
645 void coalesceFragments(BasicBlock &BB, VarLocInsertPt Before, unsigned Var,
646 unsigned StartBit, unsigned EndBit, unsigned Base,
647 DebugLoc DL, const FragsInMemMap &FragMap) {
648 if (!CoalesceAdjacentFragments)
649 return;
650 // We've inserted the location into the map. The map will have coalesced
651 // adjacent intervals (variable fragments) that describe the same memory
652 // location. Use this knowledge to insert a debug location that describes
653 // that coalesced fragment. This may eclipse other locs we've just
654 // inserted. This is okay as redundant locs will be cleaned up later.
655 auto CoalescedFrag = FragMap.find(StartBit);
656 // Bail if no coalescing has taken place.
657 if (CoalescedFrag.start() == StartBit && CoalescedFrag.stop() == EndBit)
658 return;
659
660 LLVM_DEBUG(dbgs() << "- Insert loc for bits " << CoalescedFrag.start()
661 << " to " << CoalescedFrag.stop() << "\n");
662 insertMemLoc(BB, Before, Var, CoalescedFrag.start(), CoalescedFrag.stop(),
663 Base, DL);
664 }
665
666 void addDef(const VarLocInfo &VarLoc, VarLocInsertPt Before, BasicBlock &BB,
667 VarFragMap &LiveSet) {
668 DebugVariable DbgVar = FnVarLocs->getVariable(VarLoc.VariableID);
669 if (skipVariable(DbgVar.getVariable()))
670 return;
671 // Don't bother doing anything for this variables if we know it's fully
672 // promoted. We're only interested in variables that (sometimes) live on
673 // the stack here.
674 if (!VarsWithStackSlot->count(getAggregate(DbgVar)))
675 return;
676 unsigned Var = Aggregates.insert(
677 DebugAggregate(DbgVar.getVariable(), VarLoc.DL.getInlinedAt()));
678
679 // [StartBit: EndBit) are the bits affected by this def.
680 const DIExpression *DIExpr = VarLoc.Expr;
681 unsigned StartBit;
682 unsigned EndBit;
683 if (auto Frag = DIExpr->getFragmentInfo()) {
684 StartBit = Frag->OffsetInBits;
685 EndBit = StartBit + Frag->SizeInBits;
686 } else {
687 assert(static_cast<bool>(DbgVar.getVariable()->getSizeInBits()));
688 StartBit = 0;
689 EndBit = *DbgVar.getVariable()->getSizeInBits();
690 }
691
692 // We will only fill fragments for simple memory-describing dbg.value
693 // intrinsics. If the fragment offset is the same as the offset from the
694 // base pointer, do The Thing, otherwise fall back to normal dbg.value
695 // behaviour. AssignmentTrackingLowering has generated DIExpressions
696 // written in terms of the base pointer.
697 // TODO: Remove this condition since the fragment offset doesn't always
698 // equal the offset from base pointer (e.g. for a SROA-split variable).
699 const auto DerefOffsetInBytes = getDerefOffsetInBytes(DIExpr);
700 const unsigned Base =
701 DerefOffsetInBytes && *DerefOffsetInBytes * 8 == StartBit
702 ? Bases.insert(VarLoc.Values)
703 : 0;
704 LLVM_DEBUG(dbgs() << "DEF " << DbgVar.getVariable()->getName() << " ["
705 << StartBit << ", " << EndBit << "): " << toString(Base)
706 << "\n");
707
708 // First of all, any locs that use mem that are disrupted need reinstating.
709 // Unfortunately, IntervalMap doesn't let us insert intervals that overlap
710 // with existing intervals so this code involves a lot of fiddling around
711 // with intervals to do that manually.
712 auto FragIt = LiveSet.find(Var);
713
714 // Check if the variable does not exist in the map.
715 if (FragIt == LiveSet.end()) {
716 // Add this variable to the BB map.
717 auto P = LiveSet.try_emplace(Var, FragsInMemMap(IntervalMapAlloc));
718 assert(P.second && "Var already in map?");
719 // Add the interval to the fragment map.
720 P.first->second.insert(StartBit, EndBit, Base);
721 return;
722 }
723 // The variable has an entry in the map.
724
725 FragsInMemMap &FragMap = FragIt->second;
726 // First check the easy case: the new fragment `f` doesn't overlap with any
727 // intervals.
728 if (!FragMap.overlaps(StartBit, EndBit)) {
729 LLVM_DEBUG(dbgs() << "- No overlaps\n");
730 FragMap.insert(StartBit, EndBit, Base);
731 coalesceFragments(BB, Before, Var, StartBit, EndBit, Base, VarLoc.DL,
732 FragMap);
733 return;
734 }
735 // There is at least one overlap.
736
737 // Does StartBit intersect an existing fragment?
738 auto FirstOverlap = FragMap.find(StartBit);
739 assert(FirstOverlap != FragMap.end());
740 bool IntersectStart = FirstOverlap.start() < StartBit;
741
742 // Does EndBit intersect an existing fragment?
743 auto LastOverlap = FragMap.find(EndBit);
744 bool IntersectEnd = LastOverlap.valid() && LastOverlap.start() < EndBit;
745
746 // Check if both ends of `f` intersect the same interval `i`.
747 if (IntersectStart && IntersectEnd && FirstOverlap == LastOverlap) {
748 LLVM_DEBUG(dbgs() << "- Intersect single interval @ both ends\n");
749 // Shorten `i` so that there's space to insert `f`.
750 // [ f ]
751 // [ - i - ]
752 // +
753 // [ i ][ f ][ i ]
754
755 // Save values for use after inserting a new interval.
756 auto EndBitOfOverlap = FirstOverlap.stop();
757 unsigned OverlapValue = FirstOverlap.value();
758
759 // Shorten the overlapping interval.
760 FirstOverlap.setStop(StartBit);
761 insertMemLoc(BB, Before, Var, FirstOverlap.start(), StartBit,
762 OverlapValue, VarLoc.DL);
763
764 // Insert a new interval to represent the end part.
765 FragMap.insert(EndBit, EndBitOfOverlap, OverlapValue);
766 insertMemLoc(BB, Before, Var, EndBit, EndBitOfOverlap, OverlapValue,
767 VarLoc.DL);
768
769 // Insert the new (middle) fragment now there is space.
770 FragMap.insert(StartBit, EndBit, Base);
771 } else {
772 // There's an overlap but `f` may not be fully contained within
773 // `i`. Shorten any end-point intersections so that we can then
774 // insert `f`.
775 // [ - f - ]
776 // [ - i - ]
777 // | |
778 // [ i ]
779 // Shorten any end-point intersections.
780 if (IntersectStart) {
781 LLVM_DEBUG(dbgs() << "- Intersect interval at start\n");
782 // Split off at the intersection.
783 FirstOverlap.setStop(StartBit);
784 insertMemLoc(BB, Before, Var, FirstOverlap.start(), StartBit,
785 *FirstOverlap, VarLoc.DL);
786 }
787 // [ - f - ]
788 // [ - i - ]
789 // | |
790 // [ i ]
791 if (IntersectEnd) {
792 LLVM_DEBUG(dbgs() << "- Intersect interval at end\n");
793 // Split off at the intersection.
794 LastOverlap.setStart(EndBit);
795 insertMemLoc(BB, Before, Var, EndBit, LastOverlap.stop(), *LastOverlap,
796 VarLoc.DL);
797 }
798
799 LLVM_DEBUG(dbgs() << "- Erase intervals contained within\n");
800 // FirstOverlap and LastOverlap have been shortened such that they're
801 // no longer overlapping with [StartBit, EndBit). Delete any overlaps
802 // that remain (these will be fully contained within `f`).
803 // [ - f - ] }
804 // [ - i - ] } Intersection shortening that has happened above.
805 // | | }
806 // [ i ] }
807 // -----------------
808 // [i2 ] } Intervals fully contained within `f` get erased.
809 // -----------------
810 // [ - f - ][ i ] } Completed insertion.
811 auto It = FirstOverlap;
812 if (IntersectStart)
813 ++It; // IntersectStart: first overlap has been shortened.
814 while (It.valid() && It.start() >= StartBit && It.stop() <= EndBit) {
815 LLVM_DEBUG(dbgs() << "- Erase " << toString(It));
816 It.erase(); // This increments It after removing the interval.
817 }
818 // We've dealt with all the overlaps now!
819 assert(!FragMap.overlaps(StartBit, EndBit));
820 LLVM_DEBUG(dbgs() << "- Insert DEF into now-empty space\n");
821 FragMap.insert(StartBit, EndBit, Base);
822 }
823
824 coalesceFragments(BB, Before, Var, StartBit, EndBit, Base, VarLoc.DL,
825 FragMap);
826 }
827
828 bool skipVariable(const DILocalVariable *V) { return !V->getSizeInBits(); }
829
830 void process(BasicBlock &BB, VarFragMap &LiveSet) {
831 BBInsertBeforeMap[&BB].clear();
832 for (auto &I : BB) {
833 for (DbgVariableRecord &DVR : filterDbgVars(I.getDbgRecordRange())) {
834 if (const auto *Locs = FnVarLocs->getWedge(&DVR)) {
835 for (const VarLocInfo &Loc : *Locs) {
836 addDef(Loc, &DVR, *I.getParent(), LiveSet);
837 }
838 }
839 }
840 if (const auto *Locs = FnVarLocs->getWedge(&I)) {
841 for (const VarLocInfo &Loc : *Locs) {
842 addDef(Loc, &I, *I.getParent(), LiveSet);
843 }
844 }
845 }
846 }
847
848public:
849 MemLocFragmentFill(Function &Fn,
850 const DenseSet<DebugAggregate> *VarsWithStackSlot,
851 bool CoalesceAdjacentFragments)
852 : Fn(Fn), VarsWithStackSlot(VarsWithStackSlot),
853 CoalesceAdjacentFragments(CoalesceAdjacentFragments) {}
854
855 /// Add variable locations to \p FnVarLocs so that any bits of a variable
856 /// with a memory location have that location explicitly reinstated at each
857 /// subsequent variable location definition that that doesn't overwrite those
858 /// bits. i.e. after a variable location def, insert new defs for the memory
859 /// location with fragments for the difference of "all bits currently in
860 /// memory" and "the fragment of the second def". e.g.
861 ///
862 /// Before:
863 ///
864 /// var x bits 0 to 63: value in memory
865 /// more instructions
866 /// var x bits 0 to 31: value is %0
867 ///
868 /// After:
869 ///
870 /// var x bits 0 to 63: value in memory
871 /// more instructions
872 /// var x bits 0 to 31: value is %0
873 /// var x bits 32 to 61: value in memory ; <-- new loc def
874 ///
875 void run(FunctionVarLocsBuilder *FnVarLocs) {
877 return;
878
879 this->FnVarLocs = FnVarLocs;
880
881 // Prepare for traversal.
882 //
884 std::priority_queue<unsigned int, std::vector<unsigned int>,
885 std::greater<unsigned int>>
886 Worklist;
887 std::priority_queue<unsigned int, std::vector<unsigned int>,
888 std::greater<unsigned int>>
889 Pending;
892 { // Init OrderToBB and BBToOrder.
893 unsigned int RPONumber = 0;
894 for (BasicBlock *BB : RPOT) {
895 OrderToBB[RPONumber] = BB;
896 BBToOrder[BB] = RPONumber;
897 Worklist.push(RPONumber);
898 ++RPONumber;
899 }
900 LiveIn.init(RPONumber);
901 LiveOut.init(RPONumber);
902 }
903
904 // Perform the traversal.
905 //
906 // This is a standard "intersect of predecessor outs" dataflow problem. To
907 // solve it, we perform meet() and process() using the two worklist method
908 // until the LiveIn data for each block becomes unchanging.
909 //
910 // This dataflow is essentially working on maps of sets and at each meet we
911 // intersect the maps and the mapped sets. So, initialized live-in maps
912 // monotonically decrease in value throughout the dataflow.
914 while (!Worklist.empty() || !Pending.empty()) {
915 // We track what is on the pending worklist to avoid inserting the same
916 // thing twice. We could avoid this with a custom priority queue, but
917 // this is probably not worth it.
919 LLVM_DEBUG(dbgs() << "Processing Worklist\n");
920 while (!Worklist.empty()) {
921 BasicBlock *BB = OrderToBB[Worklist.top()];
922 LLVM_DEBUG(dbgs() << "\nPop BB " << BB->getName() << "\n");
923 Worklist.pop();
924 bool InChanged = meet(*BB, Visited);
925 // Always consider LiveIn changed on the first visit.
926 InChanged |= Visited.insert(BB).second;
927 if (InChanged) {
929 << BB->getName() << " has new InLocs, process it\n");
930 // Mutate a copy of LiveIn while processing BB. Once we've processed
931 // the terminator LiveSet is the LiveOut set for BB.
932 // This is an expensive copy!
933 VarFragMap LiveSet = LiveIn[BB];
934
935 // Process the instructions in the block.
936 process(*BB, LiveSet);
937
938 // Relatively expensive check: has anything changed in LiveOut for BB?
939 if (!varFragMapsAreEqual(LiveOut[BB], LiveSet)) {
940 LLVM_DEBUG(dbgs() << BB->getName()
941 << " has new OutLocs, add succs to worklist: [ ");
942 LiveOut[BB] = std::move(LiveSet);
943 for (BasicBlock *Succ : successors(BB)) {
944 if (OnPending.insert(Succ).second) {
945 LLVM_DEBUG(dbgs() << Succ->getName() << " ");
946 Pending.push(BBToOrder[Succ]);
947 }
948 }
949 LLVM_DEBUG(dbgs() << "]\n");
950 }
951 }
952 }
953 Worklist.swap(Pending);
954 // At this point, pending must be empty, since it was just the empty
955 // worklist
956 assert(Pending.empty() && "Pending should be empty");
957 }
958
959 // Insert new location defs.
960 for (auto &Pair : BBInsertBeforeMap) {
961 InsertMap &Map = Pair.second;
962 for (auto &Pair : Map) {
963 auto InsertBefore = Pair.first;
964 assert(InsertBefore && "should never be null");
965 auto FragMemLocs = Pair.second;
966 auto &Ctx = Fn.getContext();
967
968 for (auto &FragMemLoc : FragMemLocs) {
969 DIExpression *Expr = DIExpression::get(Ctx, std::nullopt);
970 if (FragMemLoc.SizeInBits !=
971 *Aggregates[FragMemLoc.Var].first->getSizeInBits())
973 Expr, FragMemLoc.OffsetInBits, FragMemLoc.SizeInBits);
975 FragMemLoc.OffsetInBits / 8);
976 DebugVariable Var(Aggregates[FragMemLoc.Var].first, Expr,
977 FragMemLoc.DL.getInlinedAt());
978 FnVarLocs->addVarLoc(InsertBefore, Var, Expr, FragMemLoc.DL,
979 Bases[FragMemLoc.Base]);
980 }
981 }
982 }
983 }
984};
985
986/// AssignmentTrackingLowering encapsulates a dataflow analysis over a function
987/// that interprets assignment tracking debug info metadata and stores in IR to
988/// create a map of variable locations.
989class AssignmentTrackingLowering {
990public:
991 /// The kind of location in use for a variable, where Mem is the stack home,
992 /// Val is an SSA value or const, and None means that there is not one single
993 /// kind (either because there are multiple or because there is none; it may
994 /// prove useful to split this into two values in the future).
995 ///
996 /// LocKind is a join-semilattice with the partial order:
997 /// None > Mem, Val
998 ///
999 /// i.e.
1000 /// join(Mem, Mem) = Mem
1001 /// join(Val, Val) = Val
1002 /// join(Mem, Val) = None
1003 /// join(None, Mem) = None
1004 /// join(None, Val) = None
1005 /// join(None, None) = None
1006 ///
1007 /// Note: the order is not `None > Val > Mem` because we're using DIAssignID
1008 /// to name assignments and are not tracking the actual stored values.
1009 /// Therefore currently there's no way to ensure that Mem values and Val
1010 /// values are the same. This could be a future extension, though it's not
1011 /// clear that many additional locations would be recovered that way in
1012 /// practice as the likelihood of this sitation arising naturally seems
1013 /// incredibly low.
1014 enum class LocKind { Mem, Val, None };
1015
1016 /// An abstraction of the assignment of a value to a variable or memory
1017 /// location.
1018 ///
1019 /// An Assignment is Known or NoneOrPhi. A Known Assignment means we have a
1020 /// DIAssignID ptr that represents it. NoneOrPhi means that we don't (or
1021 /// can't) know the ID of the last assignment that took place.
1022 ///
1023 /// The Status of the Assignment (Known or NoneOrPhi) is another
1024 /// join-semilattice. The partial order is:
1025 /// NoneOrPhi > Known {id_0, id_1, ...id_N}
1026 ///
1027 /// i.e. for all values x and y where x != y:
1028 /// join(x, x) = x
1029 /// join(x, y) = NoneOrPhi
1031 struct Assignment {
1032 enum S { Known, NoneOrPhi } Status;
1033 /// ID of the assignment. nullptr if Status is not Known.
1034 DIAssignID *ID;
1035 /// The dbg.assign that marks this dbg-def. Mem-defs don't use this field.
1036 /// May be nullptr.
1037 AssignRecord Source;
1038
1039 bool isSameSourceAssignment(const Assignment &Other) const {
1040 // Don't include Source in the equality check. Assignments are
1041 // defined by their ID, not debug intrinsic(s).
1042 return std::tie(Status, ID) == std::tie(Other.Status, Other.ID);
1043 }
1044 void dump(raw_ostream &OS) {
1045 static const char *LUT[] = {"Known", "NoneOrPhi"};
1046 OS << LUT[Status] << "(id=";
1047 if (ID)
1048 OS << ID;
1049 else
1050 OS << "null";
1051 OS << ", s=";
1052 if (Source.isNull())
1053 OS << "null";
1054 else if (isa<DbgAssignIntrinsic *>(Source))
1055 OS << Source.get<DbgAssignIntrinsic *>();
1056 else
1057 OS << Source.get<DbgVariableRecord *>();
1058 OS << ")";
1059 }
1060
1061 static Assignment make(DIAssignID *ID, DbgAssignIntrinsic *Source) {
1062 return Assignment(Known, ID, Source);
1063 }
1064 static Assignment make(DIAssignID *ID, DbgVariableRecord *Source) {
1065 assert(Source->isDbgAssign() &&
1066 "Cannot make an assignment from a non-assign DbgVariableRecord");
1067 return Assignment(Known, ID, Source);
1068 }
1069 static Assignment make(DIAssignID *ID, AssignRecord Source) {
1070 return Assignment(Known, ID, Source);
1071 }
1072 static Assignment makeFromMemDef(DIAssignID *ID) {
1073 return Assignment(Known, ID);
1074 }
1075 static Assignment makeNoneOrPhi() { return Assignment(NoneOrPhi, nullptr); }
1076 // Again, need a Top value?
1077 Assignment() : Status(NoneOrPhi), ID(nullptr) {} // Can we delete this?
1078 Assignment(S Status, DIAssignID *ID) : Status(Status), ID(ID) {
1079 // If the Status is Known then we expect there to be an assignment ID.
1080 assert(Status == NoneOrPhi || ID);
1081 }
1082 Assignment(S Status, DIAssignID *ID, DbgAssignIntrinsic *Source)
1083 : Status(Status), ID(ID), Source(Source) {
1084 // If the Status is Known then we expect there to be an assignment ID.
1085 assert(Status == NoneOrPhi || ID);
1086 }
1087 Assignment(S Status, DIAssignID *ID, DbgVariableRecord *Source)
1088 : Status(Status), ID(ID), Source(Source) {
1089 // If the Status is Known then we expect there to be an assignment ID.
1090 assert(Status == NoneOrPhi || ID);
1091 }
1092 Assignment(S Status, DIAssignID *ID, AssignRecord Source)
1093 : Status(Status), ID(ID), Source(Source) {
1094 // If the Status is Known then we expect there to be an assignment ID.
1095 assert(Status == NoneOrPhi || ID);
1096 }
1097 };
1098
1099 using AssignmentMap = SmallVector<Assignment>;
1102 using UntaggedStoreAssignmentMap =
1103 DenseMap<const Instruction *,
1105
1106private:
1107 /// The highest numbered VariableID for partially promoted variables plus 1,
1108 /// the values for which start at 1.
1109 unsigned TrackedVariablesVectorSize = 0;
1110 /// Map a variable to the set of variables that it fully contains.
1111 OverlapMap VarContains;
1112 /// Map untagged stores to the variable fragments they assign to. Used by
1113 /// processUntaggedInstruction.
1114 UntaggedStoreAssignmentMap UntaggedStoreVars;
1115
1116 // Machinery to defer inserting dbg.values.
1118 InstInsertMap InsertBeforeMap;
1119 /// Clear the location definitions currently cached for insertion after /p
1120 /// After.
1121 void resetInsertionPoint(Instruction &After);
1122 void resetInsertionPoint(DbgVariableRecord &After);
1123
1124 // emitDbgValue can be called with:
1125 // Source=[AssignRecord|DbgValueInst*|DbgAssignIntrinsic*|DbgVariableRecord*]
1126 // Since AssignRecord can be cast to one of the latter two types, and all
1127 // other types have a shared interface, we use a template to handle the latter
1128 // three types, and an explicit overload for AssignRecord that forwards to
1129 // the template version with the right type.
1130 void emitDbgValue(LocKind Kind, AssignRecord Source, VarLocInsertPt After);
1131 template <typename T>
1132 void emitDbgValue(LocKind Kind, const T Source, VarLocInsertPt After);
1133
1134 static bool mapsAreEqual(const BitVector &Mask, const AssignmentMap &A,
1135 const AssignmentMap &B) {
1136 return llvm::all_of(Mask.set_bits(), [&](unsigned VarID) {
1137 return A[VarID].isSameSourceAssignment(B[VarID]);
1138 });
1139 }
1140
1141 /// Represents the stack and debug assignments in a block. Used to describe
1142 /// the live-in and live-out values for blocks, as well as the "current"
1143 /// value as we process each instruction in a block.
1144 struct BlockInfo {
1145 /// The set of variables (VariableID) being tracked in this block.
1146 BitVector VariableIDsInBlock;
1147 /// Dominating assignment to memory for each variable, indexed by
1148 /// VariableID.
1149 AssignmentMap StackHomeValue;
1150 /// Dominating assignemnt to each variable, indexed by VariableID.
1151 AssignmentMap DebugValue;
1152 /// Location kind for each variable. LiveLoc indicates whether the
1153 /// dominating assignment in StackHomeValue (LocKind::Mem), DebugValue
1154 /// (LocKind::Val), or neither (LocKind::None) is valid, in that order of
1155 /// preference. This cannot be derived by inspecting DebugValue and
1156 /// StackHomeValue due to the fact that there's no distinction in
1157 /// Assignment (the class) between whether an assignment is unknown or a
1158 /// merge of multiple assignments (both are Status::NoneOrPhi). In other
1159 /// words, the memory location may well be valid while both DebugValue and
1160 /// StackHomeValue contain Assignments that have a Status of NoneOrPhi.
1161 /// Indexed by VariableID.
1162 LocMap LiveLoc;
1163
1164 public:
1165 enum AssignmentKind { Stack, Debug };
1166 const AssignmentMap &getAssignmentMap(AssignmentKind Kind) const {
1167 switch (Kind) {
1168 case Stack:
1169 return StackHomeValue;
1170 case Debug:
1171 return DebugValue;
1172 }
1173 llvm_unreachable("Unknown AssignmentKind");
1174 }
1175 AssignmentMap &getAssignmentMap(AssignmentKind Kind) {
1176 return const_cast<AssignmentMap &>(
1177 const_cast<const BlockInfo *>(this)->getAssignmentMap(Kind));
1178 }
1179
1180 bool isVariableTracked(VariableID Var) const {
1181 return VariableIDsInBlock[static_cast<unsigned>(Var)];
1182 }
1183
1184 const Assignment &getAssignment(AssignmentKind Kind, VariableID Var) const {
1185 assert(isVariableTracked(Var) && "Var not tracked in block");
1186 return getAssignmentMap(Kind)[static_cast<unsigned>(Var)];
1187 }
1188
1189 LocKind getLocKind(VariableID Var) const {
1190 assert(isVariableTracked(Var) && "Var not tracked in block");
1191 return LiveLoc[static_cast<unsigned>(Var)];
1192 }
1193
1194 /// Set LocKind for \p Var only: does not set LocKind for VariableIDs of
1195 /// fragments contained win \p Var.
1196 void setLocKind(VariableID Var, LocKind K) {
1197 VariableIDsInBlock.set(static_cast<unsigned>(Var));
1198 LiveLoc[static_cast<unsigned>(Var)] = K;
1199 }
1200
1201 /// Set the assignment in the \p Kind assignment map for \p Var only: does
1202 /// not set the assignment for VariableIDs of fragments contained win \p
1203 /// Var.
1204 void setAssignment(AssignmentKind Kind, VariableID Var,
1205 const Assignment &AV) {
1206 VariableIDsInBlock.set(static_cast<unsigned>(Var));
1207 getAssignmentMap(Kind)[static_cast<unsigned>(Var)] = AV;
1208 }
1209
1210 /// Return true if there is an assignment matching \p AV in the \p Kind
1211 /// assignment map. Does consider assignments for VariableIDs of fragments
1212 /// contained win \p Var.
1213 bool hasAssignment(AssignmentKind Kind, VariableID Var,
1214 const Assignment &AV) const {
1215 if (!isVariableTracked(Var))
1216 return false;
1217 return AV.isSameSourceAssignment(getAssignment(Kind, Var));
1218 }
1219
1220 /// Compare every element in each map to determine structural equality
1221 /// (slow).
1222 bool operator==(const BlockInfo &Other) const {
1223 return VariableIDsInBlock == Other.VariableIDsInBlock &&
1224 LiveLoc == Other.LiveLoc &&
1225 mapsAreEqual(VariableIDsInBlock, StackHomeValue,
1226 Other.StackHomeValue) &&
1227 mapsAreEqual(VariableIDsInBlock, DebugValue, Other.DebugValue);
1228 }
1229 bool operator!=(const BlockInfo &Other) const { return !(*this == Other); }
1230 bool isValid() {
1231 return LiveLoc.size() == DebugValue.size() &&
1232 LiveLoc.size() == StackHomeValue.size();
1233 }
1234
1235 /// Clear everything and initialise with ⊤-values for all variables.
1236 void init(int NumVars) {
1237 StackHomeValue.clear();
1238 DebugValue.clear();
1239 LiveLoc.clear();
1240 VariableIDsInBlock = BitVector(NumVars);
1241 StackHomeValue.insert(StackHomeValue.begin(), NumVars,
1242 Assignment::makeNoneOrPhi());
1243 DebugValue.insert(DebugValue.begin(), NumVars,
1244 Assignment::makeNoneOrPhi());
1245 LiveLoc.insert(LiveLoc.begin(), NumVars, LocKind::None);
1246 }
1247
1248 /// Helper for join.
1249 template <typename ElmtType, typename FnInputType>
1250 static void joinElmt(int Index, SmallVector<ElmtType> &Target,
1251 const SmallVector<ElmtType> &A,
1252 const SmallVector<ElmtType> &B,
1253 ElmtType (*Fn)(FnInputType, FnInputType)) {
1254 Target[Index] = Fn(A[Index], B[Index]);
1255 }
1256
1257 /// See comment for AssignmentTrackingLowering::joinBlockInfo.
1258 static BlockInfo join(const BlockInfo &A, const BlockInfo &B, int NumVars) {
1259 // Join A and B.
1260 //
1261 // Intersect = join(a, b) for a in A, b in B where Var(a) == Var(b)
1262 // Difference = join(x, ⊤) for x where Var(x) is in A xor B
1263 // Join = Intersect ∪ Difference
1264 //
1265 // This is achieved by performing a join on elements from A and B with
1266 // variables common to both A and B (join elements indexed by var
1267 // intersect), then adding ⊤-value elements for vars in A xor B. The
1268 // latter part is equivalent to performing join on elements with variables
1269 // in A xor B with the ⊤-value for the map element since join(x, ⊤) = ⊤.
1270 // BlockInfo::init initializes all variable entries to the ⊤ value so we
1271 // don't need to explicitly perform that step as Join.VariableIDsInBlock
1272 // is set to the union of the variables in A and B at the end of this
1273 // function.
1274 BlockInfo Join;
1275 Join.init(NumVars);
1276
1277 BitVector Intersect = A.VariableIDsInBlock;
1278 Intersect &= B.VariableIDsInBlock;
1279
1280 for (auto VarID : Intersect.set_bits()) {
1281 joinElmt(VarID, Join.LiveLoc, A.LiveLoc, B.LiveLoc, joinKind);
1282 joinElmt(VarID, Join.DebugValue, A.DebugValue, B.DebugValue,
1283 joinAssignment);
1284 joinElmt(VarID, Join.StackHomeValue, A.StackHomeValue, B.StackHomeValue,
1285 joinAssignment);
1286 }
1287
1288 Join.VariableIDsInBlock = A.VariableIDsInBlock;
1289 Join.VariableIDsInBlock |= B.VariableIDsInBlock;
1290 assert(Join.isValid());
1291 return Join;
1292 }
1293 };
1294
1295 Function &Fn;
1296 const DataLayout &Layout;
1297 const DenseSet<DebugAggregate> *VarsWithStackSlot;
1298 FunctionVarLocsBuilder *FnVarLocs;
1301
1302 /// Helper for process methods to track variables touched each frame.
1303 DenseSet<VariableID> VarsTouchedThisFrame;
1304
1305 /// The set of variables that sometimes are not located in their stack home.
1306 DenseSet<DebugAggregate> NotAlwaysStackHomed;
1307
1308 VariableID getVariableID(const DebugVariable &Var) {
1309 return static_cast<VariableID>(FnVarLocs->insertVariable(Var));
1310 }
1311
1312 /// Join the LiveOut values of preds that are contained in \p Visited into
1313 /// LiveIn[BB]. Return True if LiveIn[BB] has changed as a result. LiveIn[BB]
1314 /// values monotonically increase. See the @link joinMethods join methods
1315 /// @endlink documentation for more info.
1316 bool join(const BasicBlock &BB, const SmallPtrSet<BasicBlock *, 16> &Visited);
1317 ///@name joinMethods
1318 /// Functions that implement `join` (the least upper bound) for the
1319 /// join-semilattice types used in the dataflow. There is an explicit bottom
1320 /// value (⊥) for some types and and explicit top value (⊤) for all types.
1321 /// By definition:
1322 ///
1323 /// Join(A, B) >= A && Join(A, B) >= B
1324 /// Join(A, ⊥) = A
1325 /// Join(A, ⊤) = ⊤
1326 ///
1327 /// These invariants are important for monotonicity.
1328 ///
1329 /// For the map-type functions, all unmapped keys in an empty map are
1330 /// associated with a bottom value (⊥). This represents their values being
1331 /// unknown. Unmapped keys in non-empty maps (joining two maps with a key
1332 /// only present in one) represents either a variable going out of scope or
1333 /// dropped debug info. It is assumed the key is associated with a top value
1334 /// (⊤) in this case (unknown location / assignment).
1335 ///@{
1336 static LocKind joinKind(LocKind A, LocKind B);
1337 static Assignment joinAssignment(const Assignment &A, const Assignment &B);
1338 BlockInfo joinBlockInfo(const BlockInfo &A, const BlockInfo &B);
1339 ///@}
1340
1341 /// Process the instructions in \p BB updating \p LiveSet along the way. \p
1342 /// LiveSet must be initialized with the current live-in locations before
1343 /// calling this.
1344 void process(BasicBlock &BB, BlockInfo *LiveSet);
1345 ///@name processMethods
1346 /// Methods to process instructions in order to update the LiveSet (current
1347 /// location information).
1348 ///@{
1349 void processNonDbgInstruction(Instruction &I, BlockInfo *LiveSet);
1350 void processDbgInstruction(DbgInfoIntrinsic &I, BlockInfo *LiveSet);
1351 /// Update \p LiveSet after encountering an instruction with a DIAssignID
1352 /// attachment, \p I.
1353 void processTaggedInstruction(Instruction &I, BlockInfo *LiveSet);
1354 /// Update \p LiveSet after encountering an instruciton without a DIAssignID
1355 /// attachment, \p I.
1356 void processUntaggedInstruction(Instruction &I, BlockInfo *LiveSet);
1357 void processDbgAssign(AssignRecord Assign, BlockInfo *LiveSet);
1358 void processDbgVariableRecord(DbgVariableRecord &DVR, BlockInfo *LiveSet);
1359 void processDbgValue(
1361 BlockInfo *LiveSet);
1362 /// Add an assignment to memory for the variable /p Var.
1363 void addMemDef(BlockInfo *LiveSet, VariableID Var, const Assignment &AV);
1364 /// Add an assignment to the variable /p Var.
1365 void addDbgDef(BlockInfo *LiveSet, VariableID Var, const Assignment &AV);
1366 ///@}
1367
1368 /// Set the LocKind for \p Var.
1369 void setLocKind(BlockInfo *LiveSet, VariableID Var, LocKind K);
1370 /// Get the live LocKind for a \p Var. Requires addMemDef or addDbgDef to
1371 /// have been called for \p Var first.
1372 LocKind getLocKind(BlockInfo *LiveSet, VariableID Var);
1373 /// Return true if \p Var has an assignment in \p M matching \p AV.
1374 bool hasVarWithAssignment(BlockInfo *LiveSet, BlockInfo::AssignmentKind Kind,
1375 VariableID Var, const Assignment &AV);
1376 /// Return the set of VariableIDs corresponding the fragments contained fully
1377 /// within the variable/fragment \p Var.
1378 ArrayRef<VariableID> getContainedFragments(VariableID Var) const;
1379
1380 /// Mark \p Var as having been touched this frame. Note, this applies only
1381 /// to the exact fragment \p Var and not to any fragments contained within.
1382 void touchFragment(VariableID Var);
1383
1384 /// Emit info for variables that are fully promoted.
1385 bool emitPromotedVarLocs(FunctionVarLocsBuilder *FnVarLocs);
1386
1387public:
1388 AssignmentTrackingLowering(Function &Fn, const DataLayout &Layout,
1389 const DenseSet<DebugAggregate> *VarsWithStackSlot)
1390 : Fn(Fn), Layout(Layout), VarsWithStackSlot(VarsWithStackSlot) {}
1391 /// Run the analysis, adding variable location info to \p FnVarLocs. Returns
1392 /// true if any variable locations have been added to FnVarLocs.
1393 bool run(FunctionVarLocsBuilder *FnVarLocs);
1394};
1395} // namespace
1396
1398AssignmentTrackingLowering::getContainedFragments(VariableID Var) const {
1399 auto R = VarContains.find(Var);
1400 if (R == VarContains.end())
1401 return std::nullopt;
1402 return R->second;
1403}
1404
1405void AssignmentTrackingLowering::touchFragment(VariableID Var) {
1406 VarsTouchedThisFrame.insert(Var);
1407}
1408
1409void AssignmentTrackingLowering::setLocKind(BlockInfo *LiveSet, VariableID Var,
1410 LocKind K) {
1411 auto SetKind = [this](BlockInfo *LiveSet, VariableID Var, LocKind K) {
1412 LiveSet->setLocKind(Var, K);
1413 touchFragment(Var);
1414 };
1415 SetKind(LiveSet, Var, K);
1416
1417 // Update the LocKind for all fragments contained within Var.
1418 for (VariableID Frag : getContainedFragments(Var))
1419 SetKind(LiveSet, Frag, K);
1420}
1421
1422AssignmentTrackingLowering::LocKind
1423AssignmentTrackingLowering::getLocKind(BlockInfo *LiveSet, VariableID Var) {
1424 return LiveSet->getLocKind(Var);
1425}
1426
1427void AssignmentTrackingLowering::addMemDef(BlockInfo *LiveSet, VariableID Var,
1428 const Assignment &AV) {
1429 LiveSet->setAssignment(BlockInfo::Stack, Var, AV);
1430
1431 // Use this assigment for all fragments contained within Var, but do not
1432 // provide a Source because we cannot convert Var's value to a value for the
1433 // fragment.
1434 Assignment FragAV = AV;
1435 FragAV.Source = nullptr;
1436 for (VariableID Frag : getContainedFragments(Var))
1437 LiveSet->setAssignment(BlockInfo::Stack, Frag, FragAV);
1438}
1439
1440void AssignmentTrackingLowering::addDbgDef(BlockInfo *LiveSet, VariableID Var,
1441 const Assignment &AV) {
1442 LiveSet->setAssignment(BlockInfo::Debug, Var, AV);
1443
1444 // Use this assigment for all fragments contained within Var, but do not
1445 // provide a Source because we cannot convert Var's value to a value for the
1446 // fragment.
1447 Assignment FragAV = AV;
1448 FragAV.Source = nullptr;
1449 for (VariableID Frag : getContainedFragments(Var))
1450 LiveSet->setAssignment(BlockInfo::Debug, Frag, FragAV);
1451}
1452
1454 return cast<DIAssignID>(I.getMetadata(LLVMContext::MD_DIAssignID));
1455}
1456
1458 return cast<DIAssignID>(DAI.getAssignID());
1459}
1460
1462 assert(DVR.isDbgAssign() &&
1463 "Cannot get a DIAssignID from a non-assign DbgVariableRecord!");
1464 return DVR.getAssignID();
1465}
1466
1467/// Return true if \p Var has an assignment in \p M matching \p AV.
1468bool AssignmentTrackingLowering::hasVarWithAssignment(
1469 BlockInfo *LiveSet, BlockInfo::AssignmentKind Kind, VariableID Var,
1470 const Assignment &AV) {
1471 if (!LiveSet->hasAssignment(Kind, Var, AV))
1472 return false;
1473
1474 // Check all the frags contained within Var as these will have all been
1475 // mapped to AV at the last store to Var.
1476 for (VariableID Frag : getContainedFragments(Var))
1477 if (!LiveSet->hasAssignment(Kind, Frag, AV))
1478 return false;
1479 return true;
1480}
1481
1482#ifndef NDEBUG
1483const char *locStr(AssignmentTrackingLowering::LocKind Loc) {
1484 using LocKind = AssignmentTrackingLowering::LocKind;
1485 switch (Loc) {
1486 case LocKind::Val:
1487 return "Val";
1488 case LocKind::Mem:
1489 return "Mem";
1490 case LocKind::None:
1491 return "None";
1492 };
1493 llvm_unreachable("unknown LocKind");
1494}
1495#endif
1496
1498 auto NextIt = ++(DVR->getIterator());
1499 if (NextIt == DVR->getMarker()->getDbgRecordRange().end())
1500 return DVR->getMarker()->MarkedInstr;
1501 return &*NextIt;
1502}
1504 const Instruction *Next = Inst->getNextNode();
1505 if (!Next->hasDbgRecords())
1506 return Next;
1507 return &*Next->getDbgRecordRange().begin();
1508}
1510 if (isa<const Instruction *>(InsertPt))
1511 return getNextNode(cast<const Instruction *>(InsertPt));
1512 return getNextNode(cast<const DbgRecord *>(InsertPt));
1513}
1514
1516 return cast<DbgAssignIntrinsic>(DVI);
1517}
1518
1520 assert(DVR->isDbgAssign() &&
1521 "Attempted to cast non-assign DbgVariableRecord to DVRAssign.");
1522 return DVR;
1523}
1524
1525void AssignmentTrackingLowering::emitDbgValue(
1526 AssignmentTrackingLowering::LocKind Kind,
1528 if (isa<DbgAssignIntrinsic *>(Source))
1529 emitDbgValue(Kind, cast<DbgAssignIntrinsic *>(Source), After);
1530 else
1531 emitDbgValue(Kind, cast<DbgVariableRecord *>(Source), After);
1532}
1533template <typename T>
1534void AssignmentTrackingLowering::emitDbgValue(
1535 AssignmentTrackingLowering::LocKind Kind, const T Source,
1537
1538 DILocation *DL = Source->getDebugLoc();
1539 auto Emit = [this, Source, After, DL](Metadata *Val, DIExpression *Expr) {
1540 assert(Expr);
1541 if (!Val)
1543 PoisonValue::get(Type::getInt1Ty(Source->getContext())));
1544
1545 // Find a suitable insert point.
1546 auto InsertBefore = getNextNode(After);
1547 assert(InsertBefore && "Shouldn't be inserting after a terminator");
1548
1549 VariableID Var = getVariableID(DebugVariable(Source));
1550 VarLocInfo VarLoc;
1551 VarLoc.VariableID = static_cast<VariableID>(Var);
1552 VarLoc.Expr = Expr;
1553 VarLoc.Values = RawLocationWrapper(Val);
1554 VarLoc.DL = DL;
1555 // Insert it into the map for later.
1556 InsertBeforeMap[InsertBefore].push_back(VarLoc);
1557 };
1558
1559 // NOTE: This block can mutate Kind.
1560 if (Kind == LocKind::Mem) {
1561 const auto *Assign = CastToDbgAssign(Source);
1562 // Check the address hasn't been dropped (e.g. the debug uses may not have
1563 // been replaced before deleting a Value).
1564 if (Assign->isKillAddress()) {
1565 // The address isn't valid so treat this as a non-memory def.
1566 Kind = LocKind::Val;
1567 } else {
1568 Value *Val = Assign->getAddress();
1569 DIExpression *Expr = Assign->getAddressExpression();
1570 assert(!Expr->getFragmentInfo() &&
1571 "fragment info should be stored in value-expression only");
1572 // Copy the fragment info over from the value-expression to the new
1573 // DIExpression.
1574 if (auto OptFragInfo = Source->getExpression()->getFragmentInfo()) {
1575 auto FragInfo = *OptFragInfo;
1577 Expr, FragInfo.OffsetInBits, FragInfo.SizeInBits);
1578 }
1579 // The address-expression has an implicit deref, add it now.
1580 std::tie(Val, Expr) =
1581 walkToAllocaAndPrependOffsetDeref(Layout, Val, Expr);
1582 Emit(ValueAsMetadata::get(Val), Expr);
1583 return;
1584 }
1585 }
1586
1587 if (Kind == LocKind::Val) {
1588 Emit(Source->getRawLocation(), Source->getExpression());
1589 return;
1590 }
1591
1592 if (Kind == LocKind::None) {
1593 Emit(nullptr, Source->getExpression());
1594 return;
1595 }
1596}
1597
1598void AssignmentTrackingLowering::processNonDbgInstruction(
1599 Instruction &I, AssignmentTrackingLowering::BlockInfo *LiveSet) {
1600 if (I.hasMetadata(LLVMContext::MD_DIAssignID))
1601 processTaggedInstruction(I, LiveSet);
1602 else
1603 processUntaggedInstruction(I, LiveSet);
1604}
1605
1606void AssignmentTrackingLowering::processUntaggedInstruction(
1607 Instruction &I, AssignmentTrackingLowering::BlockInfo *LiveSet) {
1608 // Interpret stack stores that are not tagged as an assignment in memory for
1609 // the variables associated with that address. These stores may not be tagged
1610 // because a) the store cannot be represented using dbg.assigns (non-const
1611 // length or offset) or b) the tag was accidentally dropped during
1612 // optimisations. For these stores we fall back to assuming that the stack
1613 // home is a valid location for the variables. The benefit is that this
1614 // prevents us missing an assignment and therefore incorrectly maintaining
1615 // earlier location definitions, and in many cases it should be a reasonable
1616 // assumption. However, this will occasionally lead to slight
1617 // inaccuracies. The value of a hoisted untagged store will be visible
1618 // "early", for example.
1619 assert(!I.hasMetadata(LLVMContext::MD_DIAssignID));
1620 auto It = UntaggedStoreVars.find(&I);
1621 if (It == UntaggedStoreVars.end())
1622 return; // No variables associated with the store destination.
1623
1624 LLVM_DEBUG(dbgs() << "processUntaggedInstruction on UNTAGGED INST " << I
1625 << "\n");
1626 // Iterate over the variables that this store affects, add a NoneOrPhi dbg
1627 // and mem def, set lockind to Mem, and emit a location def for each.
1628 for (auto [Var, Info] : It->second) {
1629 // This instruction is treated as both a debug and memory assignment,
1630 // meaning the memory location should be used. We don't have an assignment
1631 // ID though so use Assignment::makeNoneOrPhi() to create an imaginary one.
1632 addMemDef(LiveSet, Var, Assignment::makeNoneOrPhi());
1633 addDbgDef(LiveSet, Var, Assignment::makeNoneOrPhi());
1634 setLocKind(LiveSet, Var, LocKind::Mem);
1635 LLVM_DEBUG(dbgs() << " setting Stack LocKind to: " << locStr(LocKind::Mem)
1636 << "\n");
1637 // Build the dbg location def to insert.
1638 //
1639 // DIExpression: Add fragment and offset.
1640 DebugVariable V = FnVarLocs->getVariable(Var);
1641 DIExpression *DIE = DIExpression::get(I.getContext(), std::nullopt);
1642 if (auto Frag = V.getFragment()) {
1643 auto R = DIExpression::createFragmentExpression(DIE, Frag->OffsetInBits,
1644 Frag->SizeInBits);
1645 assert(R && "unexpected createFragmentExpression failure");
1646 DIE = *R;
1647 }
1649 if (Info.OffsetInBits)
1650 Ops = {dwarf::DW_OP_plus_uconst, Info.OffsetInBits / 8};
1651 Ops.push_back(dwarf::DW_OP_deref);
1652 DIE = DIExpression::prependOpcodes(DIE, Ops, /*StackValue=*/false,
1653 /*EntryValue=*/false);
1654 // Find a suitable insert point, before the next instruction or DbgRecord
1655 // after I.
1656 auto InsertBefore = getNextNode(&I);
1657 assert(InsertBefore && "Shouldn't be inserting after a terminator");
1658
1659 // Get DILocation for this unrecorded assignment.
1660 DILocation *InlinedAt = const_cast<DILocation *>(V.getInlinedAt());
1661 const DILocation *DILoc = DILocation::get(
1662 Fn.getContext(), 0, 0, V.getVariable()->getScope(), InlinedAt);
1663
1664 VarLocInfo VarLoc;
1665 VarLoc.VariableID = static_cast<VariableID>(Var);
1666 VarLoc.Expr = DIE;
1667 VarLoc.Values = RawLocationWrapper(
1668 ValueAsMetadata::get(const_cast<AllocaInst *>(Info.Base)));
1669 VarLoc.DL = DILoc;
1670 // 3. Insert it into the map for later.
1671 InsertBeforeMap[InsertBefore].push_back(VarLoc);
1672 }
1673}
1674
1675void AssignmentTrackingLowering::processTaggedInstruction(
1676 Instruction &I, AssignmentTrackingLowering::BlockInfo *LiveSet) {
1677 auto Linked = at::getAssignmentMarkers(&I);
1678 auto LinkedDPAssigns = at::getDVRAssignmentMarkers(&I);
1679 // No dbg.assign intrinsics linked.
1680 // FIXME: All vars that have a stack slot this store modifies that don't have
1681 // a dbg.assign linked to it should probably treat this like an untagged
1682 // store.
1683 if (Linked.empty() && LinkedDPAssigns.empty())
1684 return;
1685
1686 LLVM_DEBUG(dbgs() << "processTaggedInstruction on " << I << "\n");
1687 auto ProcessLinkedAssign = [&](auto *Assign) {
1688 VariableID Var = getVariableID(DebugVariable(Assign));
1689 // Something has gone wrong if VarsWithStackSlot doesn't contain a variable
1690 // that is linked to a store.
1691 assert(VarsWithStackSlot->count(getAggregate(Assign)) &&
1692 "expected Assign's variable to have stack slot");
1693
1694 Assignment AV = Assignment::makeFromMemDef(getIDFromInst(I));
1695 addMemDef(LiveSet, Var, AV);
1696
1697 LLVM_DEBUG(dbgs() << " linked to " << *Assign << "\n");
1698 LLVM_DEBUG(dbgs() << " LiveLoc " << locStr(getLocKind(LiveSet, Var))
1699 << " -> ");
1700
1701 // The last assignment to the stack is now AV. Check if the last debug
1702 // assignment has a matching Assignment.
1703 if (hasVarWithAssignment(LiveSet, BlockInfo::Debug, Var, AV)) {
1704 // The StackHomeValue and DebugValue for this variable match so we can
1705 // emit a stack home location here.
1706 LLVM_DEBUG(dbgs() << "Mem, Stack matches Debug program\n";);
1707 LLVM_DEBUG(dbgs() << " Stack val: "; AV.dump(dbgs()); dbgs() << "\n");
1708 LLVM_DEBUG(dbgs() << " Debug val: ";
1709 LiveSet->DebugValue[static_cast<unsigned>(Var)].dump(dbgs());
1710 dbgs() << "\n");
1711 setLocKind(LiveSet, Var, LocKind::Mem);
1712 emitDbgValue(LocKind::Mem, Assign, &I);
1713 return;
1714 }
1715
1716 // The StackHomeValue and DebugValue for this variable do not match. I.e.
1717 // The value currently stored in the stack is not what we'd expect to
1718 // see, so we cannot use emit a stack home location here. Now we will
1719 // look at the live LocKind for the variable and determine an appropriate
1720 // dbg.value to emit.
1721 LocKind PrevLoc = getLocKind(LiveSet, Var);
1722 switch (PrevLoc) {
1723 case LocKind::Val: {
1724 // The value in memory in memory has changed but we're not currently
1725 // using the memory location. Do nothing.
1726 LLVM_DEBUG(dbgs() << "Val, (unchanged)\n";);
1727 setLocKind(LiveSet, Var, LocKind::Val);
1728 } break;
1729 case LocKind::Mem: {
1730 // There's been an assignment to memory that we were using as a
1731 // location for this variable, and the Assignment doesn't match what
1732 // we'd expect to see in memory.
1733 Assignment DbgAV = LiveSet->getAssignment(BlockInfo::Debug, Var);
1734 if (DbgAV.Status == Assignment::NoneOrPhi) {
1735 // We need to terminate any previously open location now.
1736 LLVM_DEBUG(dbgs() << "None, No Debug value available\n";);
1737 setLocKind(LiveSet, Var, LocKind::None);
1738 emitDbgValue(LocKind::None, Assign, &I);
1739 } else {
1740 // The previous DebugValue Value can be used here.
1741 LLVM_DEBUG(dbgs() << "Val, Debug value is Known\n";);
1742 setLocKind(LiveSet, Var, LocKind::Val);
1743 if (DbgAV.Source) {
1744 emitDbgValue(LocKind::Val, DbgAV.Source, &I);
1745 } else {
1746 // PrevAV.Source is nullptr so we must emit undef here.
1747 emitDbgValue(LocKind::None, Assign, &I);
1748 }
1749 }
1750 } break;
1751 case LocKind::None: {
1752 // There's been an assignment to memory and we currently are
1753 // not tracking a location for the variable. Do not emit anything.
1754 LLVM_DEBUG(dbgs() << "None, (unchanged)\n";);
1755 setLocKind(LiveSet, Var, LocKind::None);
1756 } break;
1757 }
1758 };
1759 for (DbgAssignIntrinsic *DAI : Linked)
1760 ProcessLinkedAssign(DAI);
1761 for (DbgVariableRecord *DVR : LinkedDPAssigns)
1762 ProcessLinkedAssign(DVR);
1763}
1764
1765void AssignmentTrackingLowering::processDbgAssign(AssignRecord Assign,
1766 BlockInfo *LiveSet) {
1767 auto ProcessDbgAssignImpl = [&](auto *DbgAssign) {
1768 // Only bother tracking variables that are at some point stack homed. Other
1769 // variables can be dealt with trivially later.
1770 if (!VarsWithStackSlot->count(getAggregate(DbgAssign)))
1771 return;
1772
1773 VariableID Var = getVariableID(DebugVariable(DbgAssign));
1774 Assignment AV = Assignment::make(getIDFromMarker(*DbgAssign), DbgAssign);
1775 addDbgDef(LiveSet, Var, AV);
1776
1777 LLVM_DEBUG(dbgs() << "processDbgAssign on " << *DbgAssign << "\n";);
1778 LLVM_DEBUG(dbgs() << " LiveLoc " << locStr(getLocKind(LiveSet, Var))
1779 << " -> ");
1780
1781 // Check if the DebugValue and StackHomeValue both hold the same
1782 // Assignment.
1783 if (hasVarWithAssignment(LiveSet, BlockInfo::Stack, Var, AV)) {
1784 // They match. We can use the stack home because the debug intrinsics
1785 // state that an assignment happened here, and we know that specific
1786 // assignment was the last one to take place in memory for this variable.
1787 LocKind Kind;
1788 if (DbgAssign->isKillAddress()) {
1789 LLVM_DEBUG(
1790 dbgs()
1791 << "Val, Stack matches Debug program but address is killed\n";);
1792 Kind = LocKind::Val;
1793 } else {
1794 LLVM_DEBUG(dbgs() << "Mem, Stack matches Debug program\n";);
1795 Kind = LocKind::Mem;
1796 };
1797 setLocKind(LiveSet, Var, Kind);
1798 emitDbgValue(Kind, DbgAssign, DbgAssign);
1799 } else {
1800 // The last assignment to the memory location isn't the one that we want
1801 // to show to the user so emit a dbg.value(Value). Value may be undef.
1802 LLVM_DEBUG(dbgs() << "Val, Stack contents is unknown\n";);
1803 setLocKind(LiveSet, Var, LocKind::Val);
1804 emitDbgValue(LocKind::Val, DbgAssign, DbgAssign);
1805 }
1806 };
1807 if (isa<DbgVariableRecord *>(Assign))
1808 return ProcessDbgAssignImpl(cast<DbgVariableRecord *>(Assign));
1809 return ProcessDbgAssignImpl(cast<DbgAssignIntrinsic *>(Assign));
1810}
1811
1812void AssignmentTrackingLowering::processDbgValue(
1814 BlockInfo *LiveSet) {
1815 auto ProcessDbgValueImpl = [&](auto *DbgValue) {
1816 // Only other tracking variables that are at some point stack homed.
1817 // Other variables can be dealt with trivally later.
1818 if (!VarsWithStackSlot->count(getAggregate(DbgValue)))
1819 return;
1820
1821 VariableID Var = getVariableID(DebugVariable(DbgValue));
1822 // We have no ID to create an Assignment with so we mark this assignment as
1823 // NoneOrPhi. Note that the dbg.value still exists, we just cannot determine
1824 // the assignment responsible for setting this value.
1825 // This is fine; dbg.values are essentially interchangable with unlinked
1826 // dbg.assigns, and some passes such as mem2reg and instcombine add them to
1827 // PHIs for promoted variables.
1828 Assignment AV = Assignment::makeNoneOrPhi();
1829 addDbgDef(LiveSet, Var, AV);
1830
1831 LLVM_DEBUG(dbgs() << "processDbgValue on " << *DbgValue << "\n";);
1832 LLVM_DEBUG(dbgs() << " LiveLoc " << locStr(getLocKind(LiveSet, Var))
1833 << " -> Val, dbg.value override");
1834
1835 setLocKind(LiveSet, Var, LocKind::Val);
1836 emitDbgValue(LocKind::Val, DbgValue, DbgValue);
1837 };
1838 if (isa<DbgVariableRecord *>(DbgValueRecord))
1839 return ProcessDbgValueImpl(cast<DbgVariableRecord *>(DbgValueRecord));
1840 return ProcessDbgValueImpl(cast<DbgValueInst *>(DbgValueRecord));
1841}
1842
1843template <typename T> static bool hasZeroSizedFragment(T &DbgValue) {
1844 if (auto F = DbgValue.getExpression()->getFragmentInfo())
1845 return F->SizeInBits == 0;
1846 return false;
1847}
1848
1849void AssignmentTrackingLowering::processDbgInstruction(
1850 DbgInfoIntrinsic &I, AssignmentTrackingLowering::BlockInfo *LiveSet) {
1851 auto *DVI = dyn_cast<DbgVariableIntrinsic>(&I);
1852 if (!DVI)
1853 return;
1854
1855 // Ignore assignments to zero bits of the variable.
1856 if (hasZeroSizedFragment(*DVI))
1857 return;
1858
1859 if (auto *DAI = dyn_cast<DbgAssignIntrinsic>(&I))
1860 processDbgAssign(DAI, LiveSet);
1861 else if (auto *DVI = dyn_cast<DbgValueInst>(&I))
1862 processDbgValue(DVI, LiveSet);
1863}
1864void AssignmentTrackingLowering::processDbgVariableRecord(
1865 DbgVariableRecord &DVR, AssignmentTrackingLowering::BlockInfo *LiveSet) {
1866 // Ignore assignments to zero bits of the variable.
1867 if (hasZeroSizedFragment(DVR))
1868 return;
1869
1870 if (DVR.isDbgAssign())
1871 processDbgAssign(&DVR, LiveSet);
1872 else if (DVR.isDbgValue())
1873 processDbgValue(&DVR, LiveSet);
1874}
1875
1876void AssignmentTrackingLowering::resetInsertionPoint(Instruction &After) {
1877 assert(!After.isTerminator() && "Can't insert after a terminator");
1878 auto *R = InsertBeforeMap.find(getNextNode(&After));
1879 if (R == InsertBeforeMap.end())
1880 return;
1881 R->second.clear();
1882}
1883void AssignmentTrackingLowering::resetInsertionPoint(DbgVariableRecord &After) {
1884 auto *R = InsertBeforeMap.find(getNextNode(&After));
1885 if (R == InsertBeforeMap.end())
1886 return;
1887 R->second.clear();
1888}
1889
1890void AssignmentTrackingLowering::process(BasicBlock &BB, BlockInfo *LiveSet) {
1891 // If the block starts with DbgRecords, we need to process those DbgRecords as
1892 // their own frame without processing any instructions first.
1893 bool ProcessedLeadingDbgRecords = !BB.begin()->hasDbgRecords();
1894 for (auto II = BB.begin(), EI = BB.end(); II != EI;) {
1895 assert(VarsTouchedThisFrame.empty());
1896 // Process the instructions in "frames". A "frame" includes a single
1897 // non-debug instruction followed any debug instructions before the
1898 // next non-debug instruction.
1899
1900 // Skip the current instruction if it has unprocessed DbgRecords attached
1901 // (see comment above `ProcessedLeadingDbgRecords`).
1902 if (ProcessedLeadingDbgRecords) {
1903 // II is now either a debug intrinsic, a non-debug instruction with no
1904 // attached DbgRecords, or a non-debug instruction with attached processed
1905 // DbgRecords.
1906 // II has not been processed.
1907 if (!isa<DbgInfoIntrinsic>(&*II)) {
1908 if (II->isTerminator())
1909 break;
1910 resetInsertionPoint(*II);
1911 processNonDbgInstruction(*II, LiveSet);
1912 assert(LiveSet->isValid());
1913 ++II;
1914 }
1915 }
1916 // II is now either a debug intrinsic, a non-debug instruction with no
1917 // attached DbgRecords, or a non-debug instruction with attached unprocessed
1918 // DbgRecords.
1919 if (II != EI && II->hasDbgRecords()) {
1920 // Skip over non-variable debug records (i.e., labels). They're going to
1921 // be read from IR (possibly re-ordering them within the debug record
1922 // range) rather than from the analysis results.
1923 for (DbgVariableRecord &DVR : filterDbgVars(II->getDbgRecordRange())) {
1924 resetInsertionPoint(DVR);
1925 processDbgVariableRecord(DVR, LiveSet);
1926 assert(LiveSet->isValid());
1927 }
1928 }
1929 ProcessedLeadingDbgRecords = true;
1930 while (II != EI) {
1931 auto *Dbg = dyn_cast<DbgInfoIntrinsic>(&*II);
1932 if (!Dbg)
1933 break;
1934 resetInsertionPoint(*II);
1935 processDbgInstruction(*Dbg, LiveSet);
1936 assert(LiveSet->isValid());
1937 ++II;
1938 }
1939 // II is now a non-debug instruction either with no attached DbgRecords, or
1940 // with attached processed DbgRecords. II has not been processed, and all
1941 // debug instructions or DbgRecords in the frame preceding II have been
1942 // processed.
1943
1944 // We've processed everything in the "frame". Now determine which variables
1945 // cannot be represented by a dbg.declare.
1946 for (auto Var : VarsTouchedThisFrame) {
1947 LocKind Loc = getLocKind(LiveSet, Var);
1948 // If a variable's LocKind is anything other than LocKind::Mem then we
1949 // must note that it cannot be represented with a dbg.declare.
1950 // Note that this check is enough without having to check the result of
1951 // joins() because for join to produce anything other than Mem after
1952 // we've already seen a Mem we'd be joining None or Val with Mem. In that
1953 // case, we've already hit this codepath when we set the LocKind to Val
1954 // or None in that block.
1955 if (Loc != LocKind::Mem) {
1956 DebugVariable DbgVar = FnVarLocs->getVariable(Var);
1957 DebugAggregate Aggr{DbgVar.getVariable(), DbgVar.getInlinedAt()};
1958 NotAlwaysStackHomed.insert(Aggr);
1959 }
1960 }
1961 VarsTouchedThisFrame.clear();
1962 }
1963}
1964
1965AssignmentTrackingLowering::LocKind
1966AssignmentTrackingLowering::joinKind(LocKind A, LocKind B) {
1967 // Partial order:
1968 // None > Mem, Val
1969 return A == B ? A : LocKind::None;
1970}
1971
1972AssignmentTrackingLowering::Assignment
1973AssignmentTrackingLowering::joinAssignment(const Assignment &A,
1974 const Assignment &B) {
1975 // Partial order:
1976 // NoneOrPhi(null, null) > Known(v, ?s)
1977
1978 // If either are NoneOrPhi the join is NoneOrPhi.
1979 // If either value is different then the result is
1980 // NoneOrPhi (joining two values is a Phi).
1981 if (!A.isSameSourceAssignment(B))
1982 return Assignment::makeNoneOrPhi();
1983 if (A.Status == Assignment::NoneOrPhi)
1984 return Assignment::makeNoneOrPhi();
1985
1986 // Source is used to lookup the value + expression in the debug program if
1987 // the stack slot gets assigned a value earlier than expected. Because
1988 // we're only tracking the one dbg.assign, we can't capture debug PHIs.
1989 // It's unlikely that we're losing out on much coverage by avoiding that
1990 // extra work.
1991 // The Source may differ in this situation:
1992 // Pred.1:
1993 // dbg.assign i32 0, ..., !1, ...
1994 // Pred.2:
1995 // dbg.assign i32 1, ..., !1, ...
1996 // Here the same assignment (!1) was performed in both preds in the source,
1997 // but we can't use either one unless they are identical (e.g. .we don't
1998 // want to arbitrarily pick between constant values).
1999 auto JoinSource = [&]() -> AssignRecord {
2000 if (A.Source == B.Source)
2001 return A.Source;
2002 if (!A.Source || !B.Source)
2003 return AssignRecord();
2004 assert(isa<DbgVariableRecord *>(A.Source) ==
2005 isa<DbgVariableRecord *>(B.Source));
2006 if (isa<DbgVariableRecord *>(A.Source) &&
2007 cast<DbgVariableRecord *>(A.Source)->isEquivalentTo(
2008 *cast<DbgVariableRecord *>(B.Source)))
2009 return A.Source;
2010 if (isa<DbgAssignIntrinsic *>(A.Source) &&
2011 cast<DbgAssignIntrinsic *>(A.Source)->isIdenticalTo(
2012 cast<DbgAssignIntrinsic *>(B.Source)))
2013 return A.Source;
2014 return AssignRecord();
2015 };
2016 AssignRecord Source = JoinSource();
2017 assert(A.Status == B.Status && A.Status == Assignment::Known);
2018 assert(A.ID == B.ID);
2019 return Assignment::make(A.ID, Source);
2020}
2021
2022AssignmentTrackingLowering::BlockInfo
2023AssignmentTrackingLowering::joinBlockInfo(const BlockInfo &A,
2024 const BlockInfo &B) {
2025 return BlockInfo::join(A, B, TrackedVariablesVectorSize);
2026}
2027
2028bool AssignmentTrackingLowering::join(
2029 const BasicBlock &BB, const SmallPtrSet<BasicBlock *, 16> &Visited) {
2030
2032 // Ignore backedges if we have not visited the predecessor yet. As the
2033 // predecessor hasn't yet had locations propagated into it, most locations
2034 // will not yet be valid, so treat them as all being uninitialized and
2035 // potentially valid. If a location guessed to be correct here is
2036 // invalidated later, we will remove it when we revisit this block. This
2037 // is essentially the same as initialising all LocKinds and Assignments to
2038 // an implicit ⊥ value which is the identity value for the join operation.
2039 for (const BasicBlock *Pred : predecessors(&BB)) {
2040 if (Visited.count(Pred))
2041 VisitedPreds.push_back(Pred);
2042 }
2043
2044 // No preds visited yet.
2045 if (VisitedPreds.empty()) {
2046 auto It = LiveIn.try_emplace(&BB, BlockInfo());
2047 bool DidInsert = It.second;
2048 if (DidInsert)
2049 It.first->second.init(TrackedVariablesVectorSize);
2050 return /*Changed*/ DidInsert;
2051 }
2052
2053 // Exactly one visited pred. Copy the LiveOut from that pred into BB LiveIn.
2054 if (VisitedPreds.size() == 1) {
2055 const BlockInfo &PredLiveOut = LiveOut.find(VisitedPreds[0])->second;
2056 auto CurrentLiveInEntry = LiveIn.find(&BB);
2057
2058 // Check if there isn't an entry, or there is but the LiveIn set has
2059 // changed (expensive check).
2060 if (CurrentLiveInEntry == LiveIn.end())
2061 LiveIn.insert(std::make_pair(&BB, PredLiveOut));
2062 else if (PredLiveOut != CurrentLiveInEntry->second)
2063 CurrentLiveInEntry->second = PredLiveOut;
2064 else
2065 return /*Changed*/ false;
2066 return /*Changed*/ true;
2067 }
2068
2069 // More than one pred. Join LiveOuts of blocks 1 and 2.
2070 assert(VisitedPreds.size() > 1);
2071 const BlockInfo &PredLiveOut0 = LiveOut.find(VisitedPreds[0])->second;
2072 const BlockInfo &PredLiveOut1 = LiveOut.find(VisitedPreds[1])->second;
2073 BlockInfo BBLiveIn = joinBlockInfo(PredLiveOut0, PredLiveOut1);
2074
2075 // Join the LiveOuts of subsequent blocks.
2076 ArrayRef Tail = ArrayRef(VisitedPreds).drop_front(2);
2077 for (const BasicBlock *Pred : Tail) {
2078 const auto &PredLiveOut = LiveOut.find(Pred);
2079 assert(PredLiveOut != LiveOut.end() &&
2080 "block should have been processed already");
2081 BBLiveIn = joinBlockInfo(std::move(BBLiveIn), PredLiveOut->second);
2082 }
2083
2084 // Save the joined result for BB.
2085 auto CurrentLiveInEntry = LiveIn.find(&BB);
2086 // Check if there isn't an entry, or there is but the LiveIn set has changed
2087 // (expensive check).
2088 if (CurrentLiveInEntry == LiveIn.end())
2089 LiveIn.try_emplace(&BB, std::move(BBLiveIn));
2090 else if (BBLiveIn != CurrentLiveInEntry->second)
2091 CurrentLiveInEntry->second = std::move(BBLiveIn);
2092 else
2093 return /*Changed*/ false;
2094 return /*Changed*/ true;
2095}
2096
2097/// Return true if A fully contains B.
2100 auto ALeft = A.OffsetInBits;
2101 auto BLeft = B.OffsetInBits;
2102 if (BLeft < ALeft)
2103 return false;
2104
2105 auto ARight = ALeft + A.SizeInBits;
2106 auto BRight = BLeft + B.SizeInBits;
2107 if (BRight > ARight)
2108 return false;
2109 return true;
2110}
2111
2112static std::optional<at::AssignmentInfo>
2114 // Don't bother checking if this is an AllocaInst. We know this
2115 // instruction has no tag which means there are no variables associated
2116 // with it.
2117 if (const auto *SI = dyn_cast<StoreInst>(&I))
2118 return at::getAssignmentInfo(Layout, SI);
2119 if (const auto *MI = dyn_cast<MemIntrinsic>(&I))
2120 return at::getAssignmentInfo(Layout, MI);
2121 // Alloca or non-store-like inst.
2122 return std::nullopt;
2123}
2124
2126 return dyn_cast<DbgDeclareInst>(DVI);
2127}
2128
2130 return DVR->isDbgDeclare() ? DVR : nullptr;
2131}
2132
2133/// Build a map of {Variable x: Variables y} where all variable fragments
2134/// contained within the variable fragment x are in set y. This means that
2135/// y does not contain all overlaps because partial overlaps are excluded.
2136///
2137/// While we're iterating over the function, add single location defs for
2138/// dbg.declares to \p FnVarLocs.
2139///
2140/// Variables that are interesting to this pass in are added to
2141/// FnVarLocs->Variables first. TrackedVariablesVectorSize is set to the ID of
2142/// the last interesting variable plus 1, meaning variables with ID 1
2143/// (inclusive) to TrackedVariablesVectorSize (exclusive) are interesting. The
2144/// subsequent variables are either stack homed or fully promoted.
2145///
2146/// Finally, populate UntaggedStoreVars with a mapping of untagged stores to
2147/// the stored-to variable fragments.
2148///
2149/// These tasks are bundled together to reduce the number of times we need
2150/// to iterate over the function as they can be achieved together in one pass.
2152 Function &Fn, FunctionVarLocsBuilder *FnVarLocs,
2153 const DenseSet<DebugAggregate> &VarsWithStackSlot,
2155 unsigned &TrackedVariablesVectorSize) {
2157 // Map of Variable: [Fragments].
2159 // Iterate over all instructions:
2160 // - dbg.declare -> add single location variable record
2161 // - dbg.* -> Add fragments to FragmentMap
2162 // - untagged store -> Add fragments to FragmentMap and update
2163 // UntaggedStoreVars.
2164 // We need to add fragments for untagged stores too so that we can correctly
2165 // clobber overlapped fragment locations later.
2166 SmallVector<DbgDeclareInst *> InstDeclares;
2168 auto ProcessDbgRecord = [&](auto *Record, auto &DeclareList) {
2169 if (auto *Declare = DynCastToDbgDeclare(Record)) {
2170 DeclareList.push_back(Declare);
2171 return;
2172 }
2174 DebugAggregate DA = {DV.getVariable(), DV.getInlinedAt()};
2175 if (!VarsWithStackSlot.contains(DA))
2176 return;
2177 if (Seen.insert(DV).second)
2178 FragmentMap[DA].push_back(DV);
2179 };
2180 for (auto &BB : Fn) {
2181 for (auto &I : BB) {
2182 for (DbgVariableRecord &DVR : filterDbgVars(I.getDbgRecordRange()))
2183 ProcessDbgRecord(&DVR, DPDeclares);
2184 if (auto *DII = dyn_cast<DbgVariableIntrinsic>(&I)) {
2185 ProcessDbgRecord(DII, InstDeclares);
2186 } else if (auto Info = getUntaggedStoreAssignmentInfo(
2187 I, Fn.getDataLayout())) {
2188 // Find markers linked to this alloca.
2189 auto HandleDbgAssignForStore = [&](auto *Assign) {
2190 std::optional<DIExpression::FragmentInfo> FragInfo;
2191
2192 // Skip this assignment if the affected bits are outside of the
2193 // variable fragment.
2195 I.getDataLayout(), Info->Base,
2196 Info->OffsetInBits, Info->SizeInBits, Assign, FragInfo) ||
2197 (FragInfo && FragInfo->SizeInBits == 0))
2198 return;
2199
2200 // FragInfo from calculateFragmentIntersect is nullopt if the
2201 // resultant fragment matches DAI's fragment or entire variable - in
2202 // which case copy the fragment info from DAI. If FragInfo is still
2203 // nullopt after the copy it means "no fragment info" instead, which
2204 // is how it is usually interpreted.
2205 if (!FragInfo)
2206 FragInfo = Assign->getExpression()->getFragmentInfo();
2207
2208 DebugVariable DV =
2209 DebugVariable(Assign->getVariable(), FragInfo,
2210 Assign->getDebugLoc().getInlinedAt());
2211 DebugAggregate DA = {DV.getVariable(), DV.getInlinedAt()};
2212 if (!VarsWithStackSlot.contains(DA))
2213 return;
2214
2215 // Cache this info for later.
2216 UntaggedStoreVars[&I].push_back(
2217 {FnVarLocs->insertVariable(DV), *Info});
2218
2219 if (Seen.insert(DV).second)
2220 FragmentMap[DA].push_back(DV);
2221 };
2223 HandleDbgAssignForStore(DAI);
2225 HandleDbgAssignForStore(DVR);
2226 }
2227 }
2228 }
2229
2230 // Sort the fragment map for each DebugAggregate in ascending
2231 // order of fragment size - there should be no duplicates.
2232 for (auto &Pair : FragmentMap) {
2233 SmallVector<DebugVariable, 8> &Frags = Pair.second;
2234 std::sort(Frags.begin(), Frags.end(),
2235 [](const DebugVariable &Next, const DebugVariable &Elmt) {
2236 return Elmt.getFragmentOrDefault().SizeInBits >
2237 Next.getFragmentOrDefault().SizeInBits;
2238 });
2239 // Check for duplicates.
2240 assert(std::adjacent_find(Frags.begin(), Frags.end()) == Frags.end());
2241 }
2242
2243 // Build the map.
2245 for (auto &Pair : FragmentMap) {
2246 auto &Frags = Pair.second;
2247 for (auto It = Frags.begin(), IEnd = Frags.end(); It != IEnd; ++It) {
2248 DIExpression::FragmentInfo Frag = It->getFragmentOrDefault();
2249 // Find the frags that this is contained within.
2250 //
2251 // Because Frags is sorted by size and none have the same offset and
2252 // size, we know that this frag can only be contained by subsequent
2253 // elements.
2255 ++OtherIt;
2256 VariableID ThisVar = FnVarLocs->insertVariable(*It);
2257 for (; OtherIt != IEnd; ++OtherIt) {
2258 DIExpression::FragmentInfo OtherFrag = OtherIt->getFragmentOrDefault();
2259 VariableID OtherVar = FnVarLocs->insertVariable(*OtherIt);
2260 if (fullyContains(OtherFrag, Frag))
2261 Map[OtherVar].push_back(ThisVar);
2262 }
2263 }
2264 }
2265
2266 // VariableIDs are 1-based so the variable-tracking bitvector needs
2267 // NumVariables plus 1 bits.
2268 TrackedVariablesVectorSize = FnVarLocs->getNumVariables() + 1;
2269
2270 // Finally, insert the declares afterwards, so the first IDs are all
2271 // partially stack homed vars.
2272 for (auto *DDI : InstDeclares)
2273 FnVarLocs->addSingleLocVar(DebugVariable(DDI), DDI->getExpression(),
2274 DDI->getDebugLoc(), DDI->getWrappedLocation());
2275 for (auto *DVR : DPDeclares)
2276 FnVarLocs->addSingleLocVar(DebugVariable(DVR), DVR->getExpression(),
2277 DVR->getDebugLoc(),
2279 return Map;
2280}
2281
2282bool AssignmentTrackingLowering::run(FunctionVarLocsBuilder *FnVarLocsBuilder) {
2283 if (Fn.size() > MaxNumBlocks) {
2284 LLVM_DEBUG(dbgs() << "[AT] Dropping var locs in: " << Fn.getName()
2285 << ": too many blocks (" << Fn.size() << ")\n");
2286 at::deleteAll(&Fn);
2287 return false;
2288 }
2289
2290 FnVarLocs = FnVarLocsBuilder;
2291
2292 // The general structure here is inspired by VarLocBasedImpl.cpp
2293 // (LiveDebugValues).
2294
2295 // Build the variable fragment overlap map.
2296 // Note that this pass doesn't handle partial overlaps correctly (FWIW
2297 // neither does LiveDebugVariables) because that is difficult to do and
2298 // appears to be rare occurance.
2300 Fn, FnVarLocs, *VarsWithStackSlot, UntaggedStoreVars,
2301 TrackedVariablesVectorSize);
2302
2303 // Prepare for traversal.
2305 std::priority_queue<unsigned int, std::vector<unsigned int>,
2306 std::greater<unsigned int>>
2307 Worklist;
2308 std::priority_queue<unsigned int, std::vector<unsigned int>,
2309 std::greater<unsigned int>>
2310 Pending;
2313 { // Init OrderToBB and BBToOrder.
2314 unsigned int RPONumber = 0;
2315 for (BasicBlock *BB : RPOT) {
2316 OrderToBB[RPONumber] = BB;
2317 BBToOrder[BB] = RPONumber;
2318 Worklist.push(RPONumber);
2319 ++RPONumber;
2320 }
2321 LiveIn.init(RPONumber);
2322 LiveOut.init(RPONumber);
2323 }
2324
2325 // Perform the traversal.
2326 //
2327 // This is a standard "union of predecessor outs" dataflow problem. To solve
2328 // it, we perform join() and process() using the two worklist method until
2329 // the LiveIn data for each block becomes unchanging. The "proof" that this
2330 // terminates can be put together by looking at the comments around LocKind,
2331 // Assignment, and the various join methods, which show that all the elements
2332 // involved are made up of join-semilattices; LiveIn(n) can only
2333 // monotonically increase in value throughout the dataflow.
2334 //
2336 while (!Worklist.empty()) {
2337 // We track what is on the pending worklist to avoid inserting the same
2338 // thing twice.
2340 LLVM_DEBUG(dbgs() << "Processing Worklist\n");
2341 while (!Worklist.empty()) {
2342 BasicBlock *BB = OrderToBB[Worklist.top()];
2343 LLVM_DEBUG(dbgs() << "\nPop BB " << BB->getName() << "\n");
2344 Worklist.pop();
2345 bool InChanged = join(*BB, Visited);
2346 // Always consider LiveIn changed on the first visit.
2347 InChanged |= Visited.insert(BB).second;
2348 if (InChanged) {
2349 LLVM_DEBUG(dbgs() << BB->getName() << " has new InLocs, process it\n");
2350 // Mutate a copy of LiveIn while processing BB. After calling process
2351 // LiveSet is the LiveOut set for BB.
2352 BlockInfo LiveSet = LiveIn[BB];
2353
2354 // Process the instructions in the block.
2355 process(*BB, &LiveSet);
2356
2357 // Relatively expensive check: has anything changed in LiveOut for BB?
2358 if (LiveOut[BB] != LiveSet) {
2359 LLVM_DEBUG(dbgs() << BB->getName()
2360 << " has new OutLocs, add succs to worklist: [ ");
2361 LiveOut[BB] = std::move(LiveSet);
2362 for (BasicBlock *Succ : successors(BB)) {
2363 if (OnPending.insert(Succ).second) {
2364 LLVM_DEBUG(dbgs() << Succ->getName() << " ");
2365 Pending.push(BBToOrder[Succ]);
2366 }
2367 }
2368 LLVM_DEBUG(dbgs() << "]\n");
2369 }
2370 }
2371 }
2372 Worklist.swap(Pending);
2373 // At this point, pending must be empty, since it was just the empty
2374 // worklist
2375 assert(Pending.empty() && "Pending should be empty");
2376 }
2377
2378 // That's the hard part over. Now we just have some admin to do.
2379
2380 // Record whether we inserted any intrinsics.
2381 bool InsertedAnyIntrinsics = false;
2382
2383 // Identify and add defs for single location variables.
2384 //
2385 // Go through all of the defs that we plan to add. If the aggregate variable
2386 // it's a part of is not in the NotAlwaysStackHomed set we can emit a single
2387 // location def and omit the rest. Add an entry to AlwaysStackHomed so that
2388 // we can identify those uneeded defs later.
2389 DenseSet<DebugAggregate> AlwaysStackHomed;
2390 for (const auto &Pair : InsertBeforeMap) {
2391 auto &Vec = Pair.second;
2392 for (VarLocInfo VarLoc : Vec) {
2393 DebugVariable Var = FnVarLocs->getVariable(VarLoc.VariableID);
2394 DebugAggregate Aggr{Var.getVariable(), Var.getInlinedAt()};
2395
2396 // Skip this Var if it's not always stack homed.
2397 if (NotAlwaysStackHomed.contains(Aggr))
2398 continue;
2399
2400 // Skip complex cases such as when different fragments of a variable have
2401 // been split into different allocas. Skipping in this case means falling
2402 // back to using a list of defs (which could reduce coverage, but is no
2403 // less correct).
2404 bool Simple =
2405 VarLoc.Expr->getNumElements() == 1 && VarLoc.Expr->startsWithDeref();
2406 if (!Simple) {
2407 NotAlwaysStackHomed.insert(Aggr);
2408 continue;
2409 }
2410
2411 // All source assignments to this variable remain and all stores to any
2412 // part of the variable store to the same address (with varying
2413 // offsets). We can just emit a single location for the whole variable.
2414 //
2415 // Unless we've already done so, create the single location def now.
2416 if (AlwaysStackHomed.insert(Aggr).second) {
2417 assert(!VarLoc.Values.hasArgList());
2418 // TODO: When more complex cases are handled VarLoc.Expr should be
2419 // built appropriately rather than always using an empty DIExpression.
2420 // The assert below is a reminder.
2421 assert(Simple);
2422 VarLoc.Expr = DIExpression::get(Fn.getContext(), std::nullopt);
2423 DebugVariable Var = FnVarLocs->getVariable(VarLoc.VariableID);
2424 FnVarLocs->addSingleLocVar(Var, VarLoc.Expr, VarLoc.DL, VarLoc.Values);
2425 InsertedAnyIntrinsics = true;
2426 }
2427 }
2428 }
2429
2430 // Insert the other DEFs.
2431 for (const auto &[InsertBefore, Vec] : InsertBeforeMap) {
2433 for (const VarLocInfo &VarLoc : Vec) {
2434 DebugVariable Var = FnVarLocs->getVariable(VarLoc.VariableID);
2435 DebugAggregate Aggr{Var.getVariable(), Var.getInlinedAt()};
2436 // If this variable is always stack homed then we have already inserted a
2437 // dbg.declare and deleted this dbg.value.
2438 if (AlwaysStackHomed.contains(Aggr))
2439 continue;
2440 NewDefs.push_back(VarLoc);
2441 InsertedAnyIntrinsics = true;
2442 }
2443
2444 FnVarLocs->setWedge(InsertBefore, std::move(NewDefs));
2445 }
2446
2447 InsertedAnyIntrinsics |= emitPromotedVarLocs(FnVarLocs);
2448
2449 return InsertedAnyIntrinsics;
2450}
2451
2452bool AssignmentTrackingLowering::emitPromotedVarLocs(
2453 FunctionVarLocsBuilder *FnVarLocs) {
2454 bool InsertedAnyIntrinsics = false;
2455 // Go through every block, translating debug intrinsics for fully promoted
2456 // variables into FnVarLocs location defs. No analysis required for these.
2457 auto TranslateDbgRecord = [&](auto *Record) {
2458 // Skip variables that haven't been promoted - we've dealt with those
2459 // already.
2460 if (VarsWithStackSlot->contains(getAggregate(Record)))
2461 return;
2462 auto InsertBefore = getNextNode(Record);
2463 assert(InsertBefore && "Unexpected: debug intrinsics after a terminator");
2464 FnVarLocs->addVarLoc(InsertBefore, DebugVariable(Record),
2465 Record->getExpression(), Record->getDebugLoc(),
2466 RawLocationWrapper(Record->getRawLocation()));
2467 InsertedAnyIntrinsics = true;
2468 };
2469 for (auto &BB : Fn) {
2470 for (auto &I : BB) {
2471 // Skip instructions other than dbg.values and dbg.assigns.
2472 for (DbgVariableRecord &DVR : filterDbgVars(I.getDbgRecordRange()))
2473 if (DVR.isDbgValue() || DVR.isDbgAssign())
2474 TranslateDbgRecord(&DVR);
2475 auto *DVI = dyn_cast<DbgValueInst>(&I);
2476 if (DVI)
2477 TranslateDbgRecord(DVI);
2478 }
2479 }
2480 return InsertedAnyIntrinsics;
2481}
2482
2483/// Remove redundant definitions within sequences of consecutive location defs.
2484/// This is done using a backward scan to keep the last def describing a
2485/// specific variable/fragment.
2486///
2487/// This implements removeRedundantDbgInstrsUsingBackwardScan from
2488/// lib/Transforms/Utils/BasicBlockUtils.cpp for locations described with
2489/// FunctionVarLocsBuilder instead of with intrinsics.
2490static bool
2492 FunctionVarLocsBuilder &FnVarLocs) {
2493 bool Changed = false;
2494 SmallDenseMap<DebugAggregate, BitVector> VariableDefinedBytes;
2495 // Scan over the entire block, not just over the instructions mapped by
2496 // FnVarLocs, because wedges in FnVarLocs may only be separated by debug
2497 // instructions.
2498 for (const Instruction &I : reverse(*BB)) {
2499 if (!isa<DbgVariableIntrinsic>(I)) {
2500 // Sequence of consecutive defs ended. Clear map for the next one.
2501 VariableDefinedBytes.clear();
2502 }
2503
2504 auto HandleLocsForWedge = [&](auto *WedgePosition) {
2505 // Get the location defs that start just before this instruction.
2506 const auto *Locs = FnVarLocs.getWedge(WedgePosition);
2507 if (!Locs)
2508 return;
2509
2510 NumWedgesScanned++;
2511 bool ChangedThisWedge = false;
2512 // The new pruned set of defs, reversed because we're scanning backwards.
2513 SmallVector<VarLocInfo> NewDefsReversed;
2514
2515 // Iterate over the existing defs in reverse.
2516 for (auto RIt = Locs->rbegin(), REnd = Locs->rend(); RIt != REnd; ++RIt) {
2517 NumDefsScanned++;
2518 DebugAggregate Aggr =
2519 getAggregate(FnVarLocs.getVariable(RIt->VariableID));
2520 uint64_t SizeInBits = Aggr.first->getSizeInBits().value_or(0);
2521 uint64_t SizeInBytes = divideCeil(SizeInBits, 8);
2522
2523 // Cutoff for large variables to prevent expensive bitvector operations.
2524 const uint64_t MaxSizeBytes = 2048;
2525
2526 if (SizeInBytes == 0 || SizeInBytes > MaxSizeBytes) {
2527 // If the size is unknown (0) then keep this location def to be safe.
2528 // Do the same for defs of large variables, which would be expensive
2529 // to represent with a BitVector.
2530 NewDefsReversed.push_back(*RIt);
2531 continue;
2532 }
2533
2534 // Only keep this location definition if it is not fully eclipsed by
2535 // other definitions in this wedge that come after it
2536
2537 // Inert the bytes the location definition defines.
2538 auto InsertResult =
2539 VariableDefinedBytes.try_emplace(Aggr, BitVector(SizeInBytes));
2540 bool FirstDefinition = InsertResult.second;
2541 BitVector &DefinedBytes = InsertResult.first->second;
2542
2544 RIt->Expr->getFragmentInfo().value_or(
2545 DIExpression::FragmentInfo(SizeInBits, 0));
2546 bool InvalidFragment = Fragment.endInBits() > SizeInBits;
2547 uint64_t StartInBytes = Fragment.startInBits() / 8;
2548 uint64_t EndInBytes = divideCeil(Fragment.endInBits(), 8);
2549
2550 // If this defines any previously undefined bytes, keep it.
2551 if (FirstDefinition || InvalidFragment ||
2552 DefinedBytes.find_first_unset_in(StartInBytes, EndInBytes) != -1) {
2553 if (!InvalidFragment)
2554 DefinedBytes.set(StartInBytes, EndInBytes);
2555 NewDefsReversed.push_back(*RIt);
2556 continue;
2557 }
2558
2559 // Redundant def found: throw it away. Since the wedge of defs is being
2560 // rebuilt, doing nothing is the same as deleting an entry.
2561 ChangedThisWedge = true;
2562 NumDefsRemoved++;
2563 }
2564
2565 // Un-reverse the defs and replace the wedge with the pruned version.
2566 if (ChangedThisWedge) {
2567 std::reverse(NewDefsReversed.begin(), NewDefsReversed.end());
2568 FnVarLocs.setWedge(WedgePosition, std::move(NewDefsReversed));
2569 NumWedgesChanged++;
2570 Changed = true;
2571 }
2572 };
2573 HandleLocsForWedge(&I);
2574 for (DbgVariableRecord &DVR : reverse(filterDbgVars(I.getDbgRecordRange())))
2575 HandleLocsForWedge(&DVR);
2576 }
2577
2578 return Changed;
2579}
2580
2581/// Remove redundant location defs using a forward scan. This can remove a
2582/// location definition that is redundant due to indicating that a variable has
2583/// the same value as is already being indicated by an earlier def.
2584///
2585/// This implements removeRedundantDbgInstrsUsingForwardScan from
2586/// lib/Transforms/Utils/BasicBlockUtils.cpp for locations described with
2587/// FunctionVarLocsBuilder instead of with intrinsics
2588static bool
2590 FunctionVarLocsBuilder &FnVarLocs) {
2591 bool Changed = false;
2593 VariableMap;
2594
2595 // Scan over the entire block, not just over the instructions mapped by
2596 // FnVarLocs, because wedges in FnVarLocs may only be separated by debug
2597 // instructions.
2598 for (const Instruction &I : *BB) {
2599 // Get the defs that come just before this instruction.
2600 auto HandleLocsForWedge = [&](auto *WedgePosition) {
2601 const auto *Locs = FnVarLocs.getWedge(WedgePosition);
2602 if (!Locs)
2603 return;
2604
2605 NumWedgesScanned++;
2606 bool ChangedThisWedge = false;
2607 // The new pruned set of defs.
2609
2610 // Iterate over the existing defs.
2611 for (const VarLocInfo &Loc : *Locs) {
2612 NumDefsScanned++;
2613 DebugVariable Key(FnVarLocs.getVariable(Loc.VariableID).getVariable(),
2614 std::nullopt, Loc.DL.getInlinedAt());
2615 auto VMI = VariableMap.find(Key);
2616
2617 // Update the map if we found a new value/expression describing the
2618 // variable, or if the variable wasn't mapped already.
2619 if (VMI == VariableMap.end() || VMI->second.first != Loc.Values ||
2620 VMI->second.second != Loc.Expr) {
2621 VariableMap[Key] = {Loc.Values, Loc.Expr};
2622 NewDefs.push_back(Loc);
2623 continue;
2624 }
2625
2626 // Did not insert this Loc, which is the same as removing it.
2627 ChangedThisWedge = true;
2628 NumDefsRemoved++;
2629 }
2630
2631 // Replace the existing wedge with the pruned version.
2632 if (ChangedThisWedge) {
2633 FnVarLocs.setWedge(WedgePosition, std::move(NewDefs));
2634 NumWedgesChanged++;
2635 Changed = true;
2636 }
2637 };
2638
2639 for (DbgVariableRecord &DVR : filterDbgVars(I.getDbgRecordRange()))
2640 HandleLocsForWedge(&DVR);
2641 HandleLocsForWedge(&I);
2642 }
2643
2644 return Changed;
2645}
2646
2647static bool
2649 FunctionVarLocsBuilder &FnVarLocs) {
2650 assert(BB->isEntryBlock());
2651 // Do extra work to ensure that we remove semantically unimportant undefs.
2652 //
2653 // This is to work around the fact that SelectionDAG will hoist dbg.values
2654 // using argument values to the top of the entry block. That can move arg
2655 // dbg.values before undef and constant dbg.values which they previously
2656 // followed. The easiest thing to do is to just try to feed SelectionDAG
2657 // input it's happy with.
2658 //
2659 // Map of {Variable x: Fragments y} where the fragments y of variable x have
2660 // have at least one non-undef location defined already. Don't use directly,
2661 // instead call DefineBits and HasDefinedBits.
2663 VarsWithDef;
2664 // Specify that V (a fragment of A) has a non-undef location.
2665 auto DefineBits = [&VarsWithDef](DebugAggregate A, DebugVariable V) {
2666 VarsWithDef[A].insert(V.getFragmentOrDefault());
2667 };
2668 // Return true if a non-undef location has been defined for V (a fragment of
2669 // A). Doesn't imply that the location is currently non-undef, just that a
2670 // non-undef location has been seen previously.
2671 auto HasDefinedBits = [&VarsWithDef](DebugAggregate A, DebugVariable V) {
2672 auto FragsIt = VarsWithDef.find(A);
2673 if (FragsIt == VarsWithDef.end())
2674 return false;
2675 return llvm::any_of(FragsIt->second, [V](auto Frag) {
2676 return DIExpression::fragmentsOverlap(Frag, V.getFragmentOrDefault());
2677 });
2678 };
2679
2680 bool Changed = false;
2682
2683 // Scan over the entire block, not just over the instructions mapped by
2684 // FnVarLocs, because wedges in FnVarLocs may only be separated by debug
2685 // instructions.
2686 for (const Instruction &I : *BB) {
2687 // Get the defs that come just before this instruction.
2688 auto HandleLocsForWedge = [&](auto *WedgePosition) {
2689 const auto *Locs = FnVarLocs.getWedge(WedgePosition);
2690 if (!Locs)
2691 return;
2692
2693 NumWedgesScanned++;
2694 bool ChangedThisWedge = false;
2695 // The new pruned set of defs.
2697
2698 // Iterate over the existing defs.
2699 for (const VarLocInfo &Loc : *Locs) {
2700 NumDefsScanned++;
2701 DebugAggregate Aggr{FnVarLocs.getVariable(Loc.VariableID).getVariable(),
2702 Loc.DL.getInlinedAt()};
2703 DebugVariable Var = FnVarLocs.getVariable(Loc.VariableID);
2704
2705 // Remove undef entries that are encountered before any non-undef
2706 // intrinsics from the entry block.
2707 if (Loc.Values.isKillLocation(Loc.Expr) && !HasDefinedBits(Aggr, Var)) {
2708 // Did not insert this Loc, which is the same as removing it.
2709 NumDefsRemoved++;
2710 ChangedThisWedge = true;
2711 continue;
2712 }
2713
2714 DefineBits(Aggr, Var);
2715 NewDefs.push_back(Loc);
2716 }
2717
2718 // Replace the existing wedge with the pruned version.
2719 if (ChangedThisWedge) {
2720 FnVarLocs.setWedge(WedgePosition, std::move(NewDefs));
2721 NumWedgesChanged++;
2722 Changed = true;
2723 }
2724 };
2725 for (DbgVariableRecord &DVR : filterDbgVars(I.getDbgRecordRange()))
2726 HandleLocsForWedge(&DVR);
2727 HandleLocsForWedge(&I);
2728 }
2729
2730 return Changed;
2731}
2732
2734 FunctionVarLocsBuilder &FnVarLocs) {
2735 bool MadeChanges = false;
2736 MadeChanges |= removeRedundantDbgLocsUsingBackwardScan(BB, FnVarLocs);
2737 if (BB->isEntryBlock())
2738 MadeChanges |= removeUndefDbgLocsFromEntryBlock(BB, FnVarLocs);
2739 MadeChanges |= removeRedundantDbgLocsUsingForwardScan(BB, FnVarLocs);
2740
2741 if (MadeChanges)
2742 LLVM_DEBUG(dbgs() << "Removed redundant dbg locs from: " << BB->getName()
2743 << "\n");
2744 return MadeChanges;
2745}
2746
2749 for (auto &BB : Fn) {
2750 for (auto &I : BB) {
2751 // Any variable linked to an instruction is considered
2752 // interesting. Ideally we only need to check Allocas, however, a
2753 // DIAssignID might get dropped from an alloca but not stores. In that
2754 // case, we need to consider the variable interesting for NFC behaviour
2755 // with this change. TODO: Consider only looking at allocas.
2757 Result.insert({DAI->getVariable(), DAI->getDebugLoc().getInlinedAt()});
2758 }
2760 Result.insert({DVR->getVariable(), DVR->getDebugLoc().getInlinedAt()});
2761 }
2762 }
2763 }
2764 return Result;
2765}
2766
2767static void analyzeFunction(Function &Fn, const DataLayout &Layout,
2768 FunctionVarLocsBuilder *FnVarLocs) {
2769 // The analysis will generate location definitions for all variables, but we
2770 // only need to perform a dataflow on the set of variables which have a stack
2771 // slot. Find those now.
2772 DenseSet<DebugAggregate> VarsWithStackSlot = findVarsWithStackSlot(Fn);
2773
2774 bool Changed = false;
2775
2776 // Use a scope block to clean up AssignmentTrackingLowering before running
2777 // MemLocFragmentFill to reduce peak memory consumption.
2778 {
2779 AssignmentTrackingLowering Pass(Fn, Layout, &VarsWithStackSlot);
2780 Changed = Pass.run(FnVarLocs);
2781 }
2782
2783 if (Changed) {
2784 MemLocFragmentFill Pass(Fn, &VarsWithStackSlot,
2786 Pass.run(FnVarLocs);
2787
2788 // Remove redundant entries. As well as reducing memory consumption and
2789 // avoiding waiting cycles later by burning some now, this has another
2790 // important job. That is to work around some SelectionDAG quirks. See
2791 // removeRedundantDbgLocsUsingForwardScan comments for more info on that.
2792 for (auto &BB : Fn)
2793 removeRedundantDbgLocs(&BB, *FnVarLocs);
2794 }
2795}
2796
2800 if (!isAssignmentTrackingEnabled(*F.getParent()))
2801 return FunctionVarLocs();
2802
2803 auto &DL = F.getDataLayout();
2804
2805 FunctionVarLocsBuilder Builder;
2806 analyzeFunction(F, DL, &Builder);
2807
2808 // Save these results.
2810 Results.init(Builder);
2811 return Results;
2812}
2813
2814AnalysisKey DebugAssignmentTrackingAnalysis::Key;
2815
2820 return PreservedAnalyses::all();
2821}
2822
2824 if (!isAssignmentTrackingEnabled(*F.getParent()))
2825 return false;
2826
2827 LLVM_DEBUG(dbgs() << "AssignmentTrackingAnalysis run on " << F.getName()
2828 << "\n");
2829 auto DL = std::make_unique<DataLayout>(F.getParent());
2830
2831 // Clear previous results.
2832 Results->clear();
2833
2834 FunctionVarLocsBuilder Builder;
2835 analyzeFunction(F, *DL.get(), &Builder);
2836
2837 // Save these results.
2838 Results->init(Builder);
2839
2840 if (PrintResults && isFunctionInPrintList(F.getName()))
2841 Results->print(errs(), F);
2842
2843 // Return false because this pass does not modify the function.
2844 return false;
2845}
2846
2848 : FunctionPass(ID), Results(std::make_unique<FunctionVarLocs>()) {}
2849
2851
2853 "Assignment Tracking Analysis", false, true)
for(const MachineOperand &MO :llvm::drop_begin(OldMI.operands(), Desc.getNumOperands()))
MachineBasicBlock MachineBasicBlock::iterator DebugLoc DL
Function Alias Analysis Results
std::pair< const DILocalVariable *, const DILocation * > DebugAggregate
A whole (unfragmented) source variable.
VarLocInsertPt getNextNode(const DbgRecord *DVR)
static void analyzeFunction(Function &Fn, const DataLayout &Layout, FunctionVarLocsBuilder *FnVarLocs)
static std::pair< Value *, DIExpression * > walkToAllocaAndPrependOffsetDeref(const DataLayout &DL, Value *Start, DIExpression *Expression)
Walk backwards along constant GEPs and bitcasts to the base storage from Start as far as possible.
static DIAssignID * getIDFromMarker(const DbgAssignIntrinsic &DAI)
static DenseSet< DebugAggregate > findVarsWithStackSlot(Function &Fn)
static bool fullyContains(DIExpression::FragmentInfo A, DIExpression::FragmentInfo B)
Return true if A fully contains B.
static DebugAggregate getAggregate(const DbgVariableIntrinsic *DII)
static std::optional< at::AssignmentInfo > getUntaggedStoreAssignmentInfo(const Instruction &I, const DataLayout &Layout)
static AssignmentTrackingLowering::OverlapMap buildOverlapMapAndRecordDeclares(Function &Fn, FunctionVarLocsBuilder *FnVarLocs, const DenseSet< DebugAggregate > &VarsWithStackSlot, AssignmentTrackingLowering::UntaggedStoreAssignmentMap &UntaggedStoreVars, unsigned &TrackedVariablesVectorSize)
Build a map of {Variable x: Variables y} where all variable fragments contained within the variable f...
static bool removeUndefDbgLocsFromEntryBlock(const BasicBlock *BB, FunctionVarLocsBuilder &FnVarLocs)
static cl::opt< bool > PrintResults("print-debug-ata", cl::init(false), cl::Hidden)
Print the results of the analysis. Respects -filter-print-funcs.
const char * locStr(AssignmentTrackingLowering::LocKind Loc)
PointerUnion< const Instruction *, const DbgRecord * > VarLocInsertPt
static bool removeRedundantDbgLocsUsingForwardScan(const BasicBlock *BB, FunctionVarLocsBuilder &FnVarLocs)
Remove redundant location defs using a forward scan.
static bool removeRedundantDbgLocs(const BasicBlock *BB, FunctionVarLocsBuilder &FnVarLocs)
static cl::opt< bool > EnableMemLocFragFill("mem-loc-frag-fill", cl::init(true), cl::Hidden)
Option for debugging the pass, determines if the memory location fragment filling happens after gener...
static DIAssignID * getIDFromInst(const Instruction &I)
DbgAssignIntrinsic * CastToDbgAssign(DbgVariableIntrinsic *DVI)
static std::optional< int64_t > getDerefOffsetInBytes(const DIExpression *DIExpr)
Extract the offset used in DIExpr.
static bool removeRedundantDbgLocsUsingBackwardScan(const BasicBlock *BB, FunctionVarLocsBuilder &FnVarLocs)
Remove redundant definitions within sequences of consecutive location defs.
static bool hasZeroSizedFragment(T &DbgValue)
static cl::opt< cl::boolOrDefault > CoalesceAdjacentFragmentsOpt("debug-ata-coalesce-frags", cl::Hidden)
Coalesce adjacent dbg locs describing memory locations that have contiguous fragments.
static cl::opt< unsigned > MaxNumBlocks("debug-ata-max-blocks", cl::init(10000), cl::desc("Maximum num basic blocks before debug info dropped"), cl::Hidden)
static bool shouldCoalesceFragments(Function &F)
DbgDeclareInst * DynCastToDbgDeclare(DbgVariableIntrinsic *DVI)
This file implements the BitVector class.
static GCRegistry::Add< OcamlGC > B("ocaml", "ocaml 3.10-compatible GC")
static GCRegistry::Add< ErlangGC > A("erlang", "erlang-compatible garbage collector")
Analysis containing CSE Info
Definition: CSEInfo.cpp:27
dxil metadata DXIL Metadata Emit
#define LLVM_DEBUG(X)
Definition: Debug.h:101
This file defines DenseMapInfo traits for DenseMap.
This file contains constants used for implementing Dwarf debug support.
std::optional< std::vector< StOtherPiece > > Other
Definition: ELFYAML.cpp:1294
bool End
Definition: ELF_riscv.cpp:480
#define DEBUG_TYPE
IRTranslator LLVM IR MI
This file implements a coalescing interval map for small objects.
#define F(x, y, z)
Definition: MD5.cpp:55
#define I(x, y, z)
Definition: MD5.cpp:58
Module.h This file contains the declarations for the Module class.
uint64_t IntrinsicInst * II
#define P(N)
FunctionAnalysisManager FAM
bool Debug
This header defines various interfaces for pass management in LLVM.
#define INITIALIZE_PASS(passName, arg, name, cfg, analysis)
Definition: PassSupport.h:38
This file builds on the ADT/GraphTraits.h file to build a generic graph post order iterator.
static bool isValid(const char C)
Returns true if C is a valid mangled character: <0-9a-zA-Z_>.
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
Scalar Replacement Of Aggregates
Definition: SROA.cpp:5707
This file contains some templates that are useful if you are working with the STL at all.
raw_pwrite_stream & OS
This file defines the 'Statistic' class, which is designed to be an easy way to expose various metric...
#define STATISTIC(VARNAME, DESC)
Definition: Statistic.h:167
Value * RHS
Value * LHS
Helper class to build FunctionVarLocs, since that class isn't easy to modify.
void setWedge(VarLocInsertPt Before, SmallVector< VarLocInfo > &&Wedge)
Replace the defs that come just before /p Before with /p Wedge.
const SmallVectorImpl< VarLocInfo > * getWedge(VarLocInsertPt Before) const
Return ptr to wedge of defs or nullptr if no defs come just before /p Before.
void addSingleLocVar(DebugVariable Var, DIExpression *Expr, DebugLoc DL, RawLocationWrapper R)
Add a def for a variable that is valid for its lifetime.
VariableID insertVariable(DebugVariable V)
Find or insert V and return the ID.
void addVarLoc(VarLocInsertPt Before, DebugVariable Var, DIExpression *Expr, DebugLoc DL, RawLocationWrapper R)
Add a def to the wedge of defs just before /p Before.
const DebugVariable & getVariable(VariableID ID) const
Get a variable from its ID.
Class recording the (high level) value of a variable.
Class for arbitrary precision integers.
Definition: APInt.h:78
uint64_t getZExtValue() const
Get zero extended value.
Definition: APInt.h:1500
bool getBoolValue() const
Convert APInt to a boolean value.
Definition: APInt.h:451
an instruction to allocate memory on the stack
Definition: Instructions.h:61
A container for analyses that lazily runs them and caches their results.
Definition: PassManager.h:253
PassT::Result & getResult(IRUnitT &IR, ExtraArgTs... ExtraArgs)
Get the result of an analysis pass for a given IR unit.
Definition: PassManager.h:405
ArrayRef - Represent a constant reference to an array (0 or more elements consecutively in memory),...
Definition: ArrayRef.h:41
ArrayRef< T > drop_front(size_t N=1) const
Drop the first N elements of the array.
Definition: ArrayRef.h:204
bool runOnFunction(Function &F) override
runOnFunction - Virtual method overriden by subclasses to do the per-function processing of the pass.
LLVM Basic Block Representation.
Definition: BasicBlock.h:61
iterator end()
Definition: BasicBlock.h:451
iterator begin()
Instruction iterator methods.
Definition: BasicBlock.h:438
bool isEntryBlock() const
Return true if this is the entry block of the containing function.
Definition: BasicBlock.cpp:569
int find_first_unset_in(unsigned Begin, unsigned End) const
find_first_unset_in - Returns the index of the first unset bit in the range [Begin,...
Definition: BitVector.h:261
BitVector & set()
Definition: BitVector.h:351
iterator_range< const_set_bits_iterator > set_bits() const
Definition: BitVector.h:140
Assignment ID.
A structured debug information entry.
Definition: DIE.h:819
DWARF expression.
static DIExpression * append(const DIExpression *Expr, ArrayRef< uint64_t > Ops)
Append the opcodes Ops to DIExpr.
unsigned getNumElements() const
bool startsWithDeref() const
Return whether the first element a DW_OP_deref.
static std::optional< FragmentInfo > getFragmentInfo(expr_op_iterator Start, expr_op_iterator End)
Retrieve the details of this fragment expression.
ArrayRef< uint64_t > getElements() const
static std::optional< DIExpression * > createFragmentExpression(const DIExpression *Expr, unsigned OffsetInBits, unsigned SizeInBits)
Create a DIExpression to describe one part of an aggregate variable that is fragmented across multipl...
static DIExpression * prepend(const DIExpression *Expr, uint8_t Flags, int64_t Offset=0)
Prepend DIExpr with a deref and offset operation and optionally turn it into a stack value or/and an ...
static DIExpression * prependOpcodes(const DIExpression *Expr, SmallVectorImpl< uint64_t > &Ops, bool StackValue=false, bool EntryValue=false)
Prepend DIExpr with the given opcodes and optionally turn it into a stack value.
Debug location.
std::optional< uint64_t > getSizeInBits() const
Determines the size of the variable's type.
StringRef getName() const
This class represents an Operation in the Expression.
A parsed version of the target data layout string in and methods for querying it.
Definition: DataLayout.h:110
This represents the llvm.dbg.assign instruction.
DIAssignID * getAssignID() const
This represents the llvm.dbg.declare instruction.
This is the common base class for debug info intrinsics.
Instruction * MarkedInstr
Link back to the Instruction that owns this marker.
iterator_range< simple_ilist< DbgRecord >::iterator > getDbgRecordRange()
Produce a range over all the DbgRecords in this Marker.
Base class for non-instruction debug metadata records that have positions within IR.
DebugLoc getDebugLoc() const
This is the common base class for debug info intrinsics for variables.
DILocalVariable * getVariable() const
Record of a variable value-assignment, aka a non instruction representation of the dbg....
DIExpression * getExpression() const
DILocalVariable * getVariable() const
Metadata * getRawLocation() const
Returns the metadata operand for the first location description.
Result run(Function &F, FunctionAnalysisManager &FAM)
PreservedAnalyses run(Function &F, FunctionAnalysisManager &FAM)
A debug info location.
Definition: DebugLoc.h:33
DILocation * getInlinedAt() const
Definition: DebugLoc.cpp:39
Identifies a unique instance of a variable.
const DILocation * getInlinedAt() const
const DILocalVariable * getVariable() const
iterator find(const_arg_type_t< KeyT > Val)
Definition: DenseMap.h:155
std::pair< iterator, bool > try_emplace(KeyT &&Key, Ts &&... Args)
Definition: DenseMap.h:235
iterator end()
Definition: DenseMap.h:84
std::pair< iterator, bool > insert(const std::pair< KeyT, ValueT > &KV)
Definition: DenseMap.h:220
void init(unsigned InitNumEntries)
Definition: DenseMap.h:835
Implements a dense probed hash-table based set.
Definition: DenseSet.h:271
Class representing an expression and its matching format.
FunctionPass class - This class is used to implement most global optimizations.
Definition: Pass.h:311
Data structure describing the variable locations in a function.
void print(raw_ostream &OS, const Function &Fn) const
const VarLocInfo * locs_begin(const Instruction *Before) const
First variable location definition that comes before Before.
const VarLocInfo * single_locs_begin() const
const VarLocInfo * locs_end(const Instruction *Before) const
One past the last variable location definition that comes before Before.
const VarLocInfo * single_locs_end() const
One past the last single-location variable location definition.
void init(FunctionVarLocsBuilder &Builder)
const DataLayout & getDataLayout() const
Get the data layout of the module this function belongs to.
Definition: Function.cpp:362
size_t size() const
Definition: Function.h:821
LLVMContext & getContext() const
getContext - Return a reference to the LLVMContext associated with this function.
Definition: Function.cpp:358
iterator_range< simple_ilist< DbgRecord >::iterator > getDbgRecordRange() const
Return a range over the DbgRecords attached to this instruction.
Definition: Instruction.h:104
const DebugLoc & getDebugLoc() const
Return the debug location for this node as a DebugLoc.
Definition: Instruction.h:466
bool hasDbgRecords() const
Returns true if any DbgRecords are attached to this instruction.
const_iterator begin() const
Definition: IntervalMap.h:1146
void insert(KeyT a, KeyT b, ValT y)
insert - Add a mapping of [a;b] to y, coalesce with adjacent intervals.
Definition: IntervalMap.h:1129
void clear()
clear - Remove all entries.
Definition: IntervalMap.h:1330
static MDTuple * get(LLVMContext &Context, ArrayRef< Metadata * > MDs)
Definition: Metadata.h:1541
void push_back(MachineInstr *MI)
This class implements a map that also provides access to all stored values in a deterministic order.
Definition: MapVector.h:36
Root of the metadata hierarchy.
Definition: Metadata.h:62
Pass interface - Implemented by all 'passes'.
Definition: Pass.h:94
A discriminated union of two or more pointer types, with the discriminator in the low bit of the poin...
Definition: PointerUnion.h:118
void * getOpaqueValue() const
Definition: PointerUnion.h:193
static PoisonValue * get(Type *T)
Static factory methods - Return an 'poison' object of the specified type.
Definition: Constants.cpp:1852
A set of analyses that are preserved following a run of a transformation pass.
Definition: Analysis.h:111
static PreservedAnalyses all()
Construct a special preserved set that preserves all passes.
Definition: Analysis.h:117
Lightweight class that wraps the location operand metadata of a debug intrinsic.
size_type count(ConstPtrType Ptr) const
count - Return 1 if the specified pointer is in the set, 0 otherwise.
Definition: SmallPtrSet.h:412
std::pair< iterator, bool > insert(PtrType Ptr)
Inserts Ptr if and only if there is no element in the container equal to Ptr.
Definition: SmallPtrSet.h:344
SmallPtrSet - This class implements a set which is optimized for holding SmallSize or less elements.
Definition: SmallPtrSet.h:479
bool empty() const
Definition: SmallVector.h:94
size_t size() const
Definition: SmallVector.h:91
This class consists of common code factored out of the SmallVector class to reduce code duplication b...
Definition: SmallVector.h:586
reference emplace_back(ArgTypes &&... Args)
Definition: SmallVector.h:950
void push_back(const T &Elt)
Definition: SmallVector.h:426
This is a 'vector' (really, a variable-sized array), optimized for the case when the array is small.
Definition: SmallVector.h:1209
Target - Wrapper for Target specific information.
Triple - Helper class for working with autoconf configuration names.
Definition: Triple.h:44
static IntegerType * getInt1Ty(LLVMContext &C)
UniqueVector - This class produces a sequential ID number (base 1) for each unique entry that is adde...
Definition: UniqueVector.h:24
unsigned insert(const T &Entry)
insert - Append entry to the vector if it doesn't already exist.
Definition: UniqueVector.h:40
size_t size() const
size - Returns the number of entries in the vector.
Definition: UniqueVector.h:87
iterator end()
Return an iterator to the end of the vector.
Definition: UniqueVector.h:81
iterator begin()
Return an iterator to the start of the vector.
Definition: UniqueVector.h:75
static ValueAsMetadata * get(Value *V)
Definition: Metadata.cpp:495
LLVM Value Representation.
Definition: Value.h:74
StringRef getName() const
Return a constant reference to the value's name.
Definition: Value.cpp:309
std::pair< iterator, bool > insert(const ValueT &V)
Definition: DenseSet.h:206
bool contains(const_arg_type_t< ValueT > V) const
Check if the set contains the given element.
Definition: DenseSet.h:185
size_type count(const_arg_type_t< ValueT > V) const
Return 1 if the specified key is in the set, 0 otherwise.
Definition: DenseSet.h:97
self_iterator getIterator()
Definition: ilist_node.h:132
NodeTy * getNextNode()
Get the next node, or nullptr for the list tail.
Definition: ilist_node.h:353
This class implements an extremely fast bulk output stream that can only output to a stream.
Definition: raw_ostream.h:52
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
constexpr std::underlying_type_t< E > Mask()
Get a bitmask with 1s in all places up to the high-order bit of E's largest value.
Definition: BitmaskEnum.h:121
@ Tail
Attemps to make calls as fast as possible while guaranteeing that tail call optimization can always b...
Definition: CallingConv.h:76
unsigned ID
LLVM IR allows to use arbitrary numbers as calling convention identifiers.
Definition: CallingConv.h:24
void deleteAll(Function *F)
Remove all Assignment Tracking related intrinsics and metadata from F.
Definition: DebugInfo.cpp:1847
AssignmentMarkerRange getAssignmentMarkers(DIAssignID *ID)
Return a range of dbg.assign intrinsics which use \ID as an operand.
Definition: DebugInfo.cpp:1808
SmallVector< DbgVariableRecord * > getDVRAssignmentMarkers(const Instruction *Inst)
Definition: DebugInfo.h:238
std::optional< AssignmentInfo > getAssignmentInfo(const DataLayout &DL, const MemIntrinsic *I)
Definition: DebugInfo.cpp:1969
bool calculateFragmentIntersect(const DataLayout &DL, const Value *Dest, uint64_t SliceOffsetInBits, uint64_t SliceSizeInBits, const DbgAssignIntrinsic *DbgAssign, std::optional< DIExpression::FragmentInfo > &Result)
Calculate the fragment of the variable in DAI covered from (Dest + SliceOffsetInBits) to to (Dest + S...
Definition: DebugInfo.cpp:1903
initializer< Ty > init(const Ty &Val)
Definition: CommandLine.h:443
std::optional< const char * > toString(const std::optional< DWARFFormValue > &V)
Take an optional DWARFFormValue and try to extract a string value from it.
@ DW_OP_LLVM_fragment
Only used in LLVM metadata.
Definition: Dwarf.h:142
PointerTypeMap run(const Module &M)
Compute the PointerTypeMap for the module M.
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
void dump(const SparseBitVector< ElementSize > &LHS, raw_ostream &out)
@ Offset
Definition: DWP.cpp:480
bool all_of(R &&range, UnaryPredicate P)
Provide wrappers to std::all_of which take ranges instead of having to pass begin/end explicitly.
Definition: STLExtras.h:1722
auto successors(const MachineBasicBlock *BB)
bool operator!=(uint64_t V1, const APInt &V2)
Definition: APInt.h:2062
bool operator==(const AddressRangeValuePair &LHS, const AddressRangeValuePair &RHS)
Printable print(const GCNRegPressure &RP, const GCNSubtarget *ST=nullptr)
bool any_of(R &&range, UnaryPredicate P)
Provide wrappers to std::any_of which take ranges instead of having to pass begin/end explicitly.
Definition: STLExtras.h:1729
auto reverse(ContainerTy &&C)
Definition: STLExtras.h:419
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:163
bool isFunctionInPrintList(StringRef FunctionName)
VariableID
Type wrapper for integer ID for Variables. 0 is reserved.
raw_fd_ostream & errs()
This returns a reference to a raw_ostream for standard error.
constexpr T divideCeil(U Numerator, V Denominator)
Returns the integer ceil(Numerator / Denominator).
Definition: MathExtras.h:403
bool isAssignmentTrackingEnabled(const Module &M)
Return true if assignment tracking is enabled for module M.
Definition: DebugInfo.cpp:2242
auto predecessors(const MachineBasicBlock *BB)
static auto filterDbgVars(iterator_range< simple_ilist< DbgRecord >::iterator > R)
Filter the DbgRecord range to DbgVariableRecord types only and downcast.
bool debuginfoShouldUseDebugInstrRef(const Triple &T)
Implement std::hash so that hash_code can be used in STL containers.
Definition: BitVector.h:858
A special type used by analysis passes to provide an address that identifies that particular analysis...
Definition: Analysis.h:28
uint64_t startInBits() const
Return the index of the first bit of the fragment.
uint64_t endInBits() const
Return the index of the bit after the end of the fragment, e.g.
static bool isEqual(const VariableID &LHS, const VariableID &RHS)
static unsigned getHashValue(const VariableID &Val)
An information struct used to provide DenseMap with the various necessary components for a given valu...
Definition: DenseMapInfo.h:52
Variable location definition used by FunctionVarLocs.
RawLocationWrapper Values
result_type operator()(const argument_type &Arg) const