llvm/lib/DWARFLinkerParallel/DependencyTracker.h

   1 //===- "DependencyTracker.h" ------------------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef LLVM_LIB_DWARFLINKERPARALLEL_DEPENDENCYTRACKER_H
  10 #define LLVM_LIB_DWARFLINKERPARALLEL_DEPENDENCYTRACKER_H
  11
  12 #include "DWARFLinkerCompileUnit.h"
  13 #include "DWARFLinkerImpl.h"
  14 #include "llvm/ADT/SmallVector.h"
  15
  16 namespace llvm {
  17 class DWARFDebugInfoEntry;
  18 class DWARFDie;
  19
  20 namespace dwarflinker_parallel {
  21
  22 /// This class discovers DIEs dependencies and marks "live" DIEs.
  23 class DependencyTracker {
  24 public:
  25   DependencyTracker(DWARFLinkerImpl::LinkContext &Context) : Context(Context) {}
  26
  27   /// Recursively walk the \p DIE tree and look for DIEs to keep. Store that
  28   /// information in \p CU's DIEInfo.
  29   ///
  30   /// This function is the entry point of the DIE selection algorithm. It is
  31   /// expected to walk the DIE tree and(through the mediation of
  32   /// Context.File.Addresses) ask for relocation adjustment value on each
  33   /// DIE that might be a 'root DIE'.
  34   ///
  35   /// Returns true if all dependencies are correctly discovered. Inter-CU
  36   /// dependencies cannot be discovered if referenced CU is not analyzed yet.
  37   /// If that is the case this method returns false.
  38   bool resolveDependenciesAndMarkLiveness(CompileUnit &CU);
  39
  40   /// Recursively walk the \p DIE tree and check "keepness" information.
  41   /// It is an error if parent node does not have "keep" flag, while
  42   /// child have one. This function dump error at stderr in that case.
  43 #ifndef NDEBUG
  44   static void verifyKeepChain(CompileUnit &CU);
  45 #endif
  46
  47 protected:
  48   struct RootEntryTy {
  49     RootEntryTy(CompileUnit &CU, const DWARFDebugInfoEntry *RootEntry)
  50         : CU(CU), RootEntry(RootEntry) {}
  51
  52     // Compile unit keeping root entry.
  53     CompileUnit &CU;
  54
  55     // Root entry.
  56     const DWARFDebugInfoEntry *RootEntry;
  57   };
  58
  59   using RootEntriesListTy = SmallVector<RootEntryTy>;
  60
  61   /// This function navigates DIEs tree starting from specified \p Entry.
  62   /// It puts 'root DIE' into the worklist.
  63   void collectRootsToKeep(CompileUnit &CU, const DWARFDebugInfoEntry *Entry);
  64
  65   /// Returns true if specified variable references live code section.
  66   bool isLiveVariableEntry(CompileUnit &CU, const DWARFDebugInfoEntry *Entry);
  67
  68   /// Returns true if specified subprogram references live code section.
  69   bool isLiveSubprogramEntry(CompileUnit &CU, const DWARFDebugInfoEntry *Entry);
  70
  71   /// Examine worklist and mark all 'root DIE's as kept.
  72   bool markLiveRootsAsKept();
  73
  74   /// Mark whole DIE tree as kept recursively.
  75   bool markDIEEntryAsKeptRec(const RootEntryTy &RootItem, CompileUnit &CU,
  76                              const DWARFDebugInfoEntry *Entry);
  77
  78   /// Check referenced DIEs and add them into the worklist if neccessary.
  79   bool maybeAddReferencedRoots(const RootEntryTy &RootItem, CompileUnit &CU,
  80                                const DWARFDebugInfoEntry *Entry);
  81
  82   /// Add 'root DIE' into the worklist.
  83   void addItemToWorklist(CompileUnit &CU, const DWARFDebugInfoEntry *Entry);
  84
  85   /// Set kind of placement(whether it goes into type table, plain dwarf or
  86   /// both) for the specified die \p DieIdx.
  87   void setDIEPlacementAndTypename(CompileUnit::DIEInfo &Info);
  88
  89   /// Flag indicating whether liveness information should be examined.
  90   bool TrackLiveness = false;
  91
  92   /// List of CU, Entry pairs which are 'root DIE's.
  93   RootEntriesListTy RootEntriesWorkList;
  94
  95   /// Link context for the analyzed CU.
  96   DWARFLinkerImpl::LinkContext &Context;
  97 };
  98
  99 } // end namespace dwarflinker_parallel
 100 } // end namespace llvm
 101
 102 #endif // LLVM_LIB_DWARFLINKERPARALLEL_DEPENDENCYTRACKER_H