Add --emit-symbol-resolution-report option for a standalone JSON report

include/eld/Config/GeneralOptions.h

@@ -522,6 +522,19 @@ class GeneralOptions {
     return ArchiveMemberReportFile;
   }
 
+  // --emit-symbol-resolution-report
+  void setSymbolResolutionReportFile(llvm::StringRef File) {
+    SymbolResolutionReportFile = File.str();
+  }
+
+  const std::optional<std::string> &getSymbolResolutionReportFile() const {
+    return SymbolResolutionReportFile;
+  }
+
+  bool shouldEmitSymbolResolutionReport() const {
+    return SymbolResolutionReportFile.has_value();
+  }
+
   // --ld-generated-unwind-info
   void setGenUnwindInfo(bool PEnable = true) { BGenUnwindInfo = PEnable; }
 
@@ -1364,6 +1377,8 @@ class GeneralOptions {
   std::optional<std::string> PluginActivityLogFile; // --plugin-activity-file output path
   std::optional<std::string>
       ArchiveMemberReportFile;           // --archive-member-report output path
+  std::optional<std::string>
+      SymbolResolutionReportFile; // --emit-symbol-resolution-report output path
   std::string MappingFileName;           // --Mapping-file
   std::string MappingDumpFile;           // --dump-mapping-file
   std::string ResponseDumpFile;          // --dump-response-file

include/eld/Core/Linker.h

@@ -85,6 +85,11 @@ class Linker {
 
   void printLayout();
 
+  /// Emits the JSON symbol resolution report. This function
+  /// must only be called if symbol resolution report is
+  /// requested.
+  bool emitSymbolResolutionReport();
+
   void unloadPlugins();
 
   // Set the GNU linker driver after sniffing

include/eld/Driver/GnuLinkerOptions.td

@@ -1556,6 +1556,13 @@ defm ArchiveMemberReportFile
       MetaVarName<"<filename>">,
       Group<grp_miscfeatures>;
 
+defm SymbolResolutionReportFile
+    : mDashDeprEqWithOpt<"emit-symbol-resolution-report",
+                         "SymbolResolutionReportFile",
+                         "Emit JSON symbol resolution report">,
+      MetaVarName<"<filename>">,
+      Group<grp_miscfeatures>;
+
 //===----------------------------------------------------------------------===//
 /// Help!
 //===----------------------------------------------------------------------===//

include/eld/LayoutMap/LayoutInfo.h

@@ -81,8 +81,7 @@ class LayoutInfo {
     ShowTiming = 0x20,
     ShowDebugStrings = 0x40,
     ShowRelativePath = 0x80,
-    ShowInitialLayout = 0x100,
-    ShowSymbolResolution = 0x200
+    ShowInitialLayout = 0x100
   };
 
   enum InputKindPrefix {
@@ -419,10 +418,6 @@ class LayoutInfo {
 
   void printStats(void *H, llvm::raw_ostream &OS) const;
 
-  bool showSymbolResolution() const {
-    return LayoutDetail & LayoutDetail::ShowSymbolResolution;
-  }
-
 private:
   Stats LinkStats;
   std::vector<std::string> Features;

include/eld/LayoutMap/TextLayoutPrinter.h

@@ -170,8 +170,6 @@ class TextLayoutPrinter {
   void printFragments(Module &Module, ELFSection &OutSect, RuleContainer &R,
                       bool UseColor);
 
-  void printSymbolResolution(Module &Module);
-
   void printOffsetHelper(bool HasOffset, std::function<void()> F) const;
 
 private:

include/eld/Object/ObjectLinker.h

@@ -399,6 +399,8 @@ class ObjectLinker {
 
   bool emitArchiveMemberReport(llvm::StringRef Filename) const;
 
+  bool emitSymbolResolutionReport(llvm::StringRef Filename) const;
+
 private:
   /// Assigns version nodes to symbols with GNU ld semantics:
   /// - Pass 1: Exact matches (forward order, first wins, warns on reassign)

include/eld/SymbolResolver/NamePool.h

@@ -82,8 +82,7 @@ class NamePool {
                     DiagnosticPrinter *Printer);
 
   LDSymbol *createPluginSymbol(InputFile *Input, std::string SymbolName,
-                               Fragment *CurFragment, uint64_t Val,
-                               LayoutInfo *layoutInfo);
+                               Fragment *CurFragment, uint64_t Val);
 
   size_t getNumGlobalSize() const { return GlobalSymbols.size(); }
 

include/eld/SymbolResolver/SymbolInfo.h

@@ -75,6 +75,7 @@ class SymbolInfo {
         : SymBinding(0), SymType(0), SymVisibility(0), SymSectIndexKind(0),
           IsBitcode(0) {}
     unsigned int SymBinding : 2;
+    // FIXME: SymType needs 4 bits.
     unsigned int SymType : 2;
     unsigned int SymVisibility : 2;
     unsigned int SymSectIndexKind : 3;
@@ -87,6 +88,7 @@ class SymbolInfo {
   void setSymbolSectionIndexKind(ResolveInfo::Binding Binding,
                                  ResolveInfo::Desc SymDesc);
   void setBitcodeAttribute(bool IsBitcode);
+  // FIXME: Is the below bit pattern correct?
   /// Information is stored as follows in this bitfield:
   /// 0b000000000000000000000sssvvttttbb
   /// b: bits used to represent symbol binding.
@@ -99,4 +101,4 @@ class SymbolInfo {
 };
 } // namespace eld
 
-#endif
+#endif

include/eld/SymbolResolver/SymbolResolutionInfo.h

@@ -10,6 +10,7 @@
 #include "llvm/ADT/MapVector.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/Support/JSON.h"
 #include <optional>
 
 namespace eld {
@@ -18,6 +19,7 @@ class GeneralOptions;
 class LDSymbol;
 class LinkerConfig;
 class LinkerScript;
+class Module;
 class NamePool;
 class Plugin;
 
@@ -29,8 +31,21 @@ class SymbolResolutionInfo {
   using CandidatesTableType = llvm::StringMap<CandidatesType>;
   using SymbolInfoMapType = llvm::MapVector<const LDSymbol *, SymbolInfo>;
 
-  std::string getSymbolInfoAsString(const LDSymbol *Sym,
-                                    const GeneralOptions &Options);
+  /// Returns the (decorated) section name for a defined symbol, or an empty
+  /// string when the symbol has no associated section (Undef/Abs/unknown
+  /// bitcode section).
+  std::string getSymbolSectionName(const LDSymbol *Sym,
+                                   const SymbolInfo &SymInfo,
+                                   const GeneralOptions &Options) const;
+
+  /// Returns the plugin that provided the symbol, or nullptr for
+  /// non-plugin symbols.
+  const Plugin *getSymbolPlugin(const LDSymbol *Sym) const {
+    auto Iter = SymbolToPluginMap.find(Sym);
+    if (Iter != SymbolToPluginMap.end())
+      return Iter->second;
+    return nullptr;
+  }
 
   /// Setup symbol resolution candidates information. This information is
   /// required for creating symbol resolution report. This function does two
@@ -61,7 +76,17 @@ class SymbolResolutionInfo {
     SymbolToPluginMap[Sym] = Plugin;
   }
 
+  /// Emits the symbol resolution report as standalone JSON to \p Filename.
+  /// Returns false (and raises a diagnostic) if the file cannot be written.
+  bool emitSymbolResolutionReport(Module &CurModule, llvm::StringRef Filename);
+
 private:
+  /// Builds the JSON object describing a single symbol resolution candidate.
+  llvm::json::Object buildCandidateObject(const LDSymbol *Candidate,
+                                          const SymbolInfo &SymInfo,
+                                          const GeneralOptions &Options,
+                                          bool IsSelected);
+
   CandidatesTableType Candidates;
   SymbolInfoMapType SymbolInfoMap;
   std::vector<const LDSymbol *> LTOObjectSymbols;

lib/Core/Linker.cpp

@@ -258,6 +258,12 @@ void Linker::printLayout() {
   ObjLinker->printlayout();
 }
 
+bool Linker::emitSymbolResolutionReport() {
+  const GeneralOptions &Options = ThisConfig->options();
+  return ObjLinker->emitSymbolResolutionReport(
+      *Options.getSymbolResolutionReportFile());
+}
+
 bool Linker::activateInputs(std::vector<InputAction *> &Actions) {
   LinkerProgress->incrementAndDisplayProgress();
   for (auto &Action : Actions) {

lib/Core/Module.cpp

@@ -509,12 +509,20 @@ llvm::StringRef Module::getStateStr() const {
 void Module::addSymbolCreatedByPluginToFragment(Fragment *F, std::string Symbol,
                                                 uint64_t Val,
                                                 const eld::Plugin *Plugin) {
-  LayoutInfo *layoutInfo = getLayoutInfo();
   LDSymbol *S = SymbolNamePool.createPluginSymbol(
-      getInternalInput(Module::InternalInputType::Plugin), Symbol, F, Val,
-      layoutInfo);
-  if (S && layoutInfo && layoutInfo->showSymbolResolution())
-    SymbolNamePool.getSRI().recordPluginSymbol(S, Plugin);
+      getInternalInput(Module::InternalInputType::Plugin), Symbol, F, Val);
+  if (S && ThisConfig.options().shouldEmitSymbolResolutionReport()) {
+    const ResolveInfo *Info = S->resolveInfo();
+    SymbolResolutionInfo &SRI = SymbolNamePool.getSRI();
+    SRI.recordSymbolInfo(
+        S, SymbolInfo{Info->resolvedOrigin(), Info->size(),
+                      static_cast<ResolveInfo::Binding>(Info->binding()),
+                      static_cast<ResolveInfo::Type>(Info->type()),
+                      Info->visibility(),
+                      static_cast<ResolveInfo::Desc>(Info->desc()),
+                      /*isBitcode=*/false});
+    SRI.recordPluginSymbol(S, Plugin);
+  }
   PluginFragmentToSymbols[F];
   PluginFragmentToSymbols[F].push_back(S);
   llvm::dyn_cast<eld::ObjectFile>(F->getOwningSection()->getInputFile())

lib/LayoutMap/LayoutInfo.cpp

@@ -182,7 +182,6 @@ LayoutInfo::setLayoutDetail(llvm::StringRef Option,
           .Case("show-timing", ShowTiming)
           .Case("show-debug-strings", ShowDebugStrings)
           .Case("show-initial-layout", ShowInitialLayout)
-          .Case("show-symbol-resolution", ShowSymbolResolution)
           .StartsWith(ShowRelativePathOptionStr, ShowRelativePath)
           .Default(0);
   LayoutDetail |= OptionLayoutDetail;

lib/LayoutMap/TextLayoutPrinter.cpp

@@ -1338,9 +1338,6 @@ void TextLayoutPrinter::printMapFile(eld::Module &Module) {
 
   if (!ThisLayoutInfo->showOnlyLayout())
     printPluginInfo(Module);
-
-  if (ThisLayoutInfo->showSymbolResolution())
-    printSymbolResolution(Module);
 }
 
 void TextLayoutPrinter::printLayout(eld::Module &Module) {
@@ -1536,51 +1533,6 @@ void TextLayoutPrinter::printFragments(Module &Module, ELFSection &OutSect,
   }
 }
 
-void TextLayoutPrinter::printSymbolResolution(Module &Module) {
-  NamePool &NP = Module.getNamePool();
-  SymbolResolutionInfo &SRI = NP.getSRI();
-  const auto &Symbols = Module.getSymbols();
-  const GeneralOptions &Options = ThisLayoutInfo->getConfig().options();
-  SRI.setupCandidatesInfo(NP, Module.getScript());
-
-  outputStream() << "# Symbol Resolution: "
-                 << "\n";
-
-  size_t Index = 0;
-  for (const auto *RI : Symbols) {
-    if (RI->isLocal() &&
-        RI->resolvedOrigin() != Module.getInternalInput(Module::Plugin))
-      continue;
-    ++Index;
-    llvm::StringRef SymName = RI->getName();
-    const SymbolResolutionInfo::CandidatesType Candidates =
-        SRI.getCandidates(SymName);
-    outputStream() << Index << ") " << SymName << "\n";
-    for (const auto &Candidate : Candidates) {
-      std::optional<SymbolInfo> OptSymbolInfo = SRI.getSymbolInfo(Candidate);
-      ASSERT(OptSymbolInfo, "Symbol info must be present!");
-      SymbolInfo CandidateInfo = OptSymbolInfo.value();
-
-      std::string CandidateInfoAsString =
-          SRI.getSymbolInfoAsString(Candidate, Options);
-      outputStream() << "\t" << CandidateInfoAsString;
-      if (Candidate->resolveInfo()->outSymbol() == Candidate ||
-          (CandidateInfo.isBitcodeSymbol() &&
-           CandidateInfo.getInputFile() ==
-               Candidate->resolveInfo()->resolvedOrigin()))
-        outputStream() << " [Selected]";
-      if (CandidateInfo.isBitcodeSymbol()) {
-        if (const LDSymbol *LTOSym =
-                SRI.getCorrespondingLTOObjectSymIfAny(Candidate)) {
-          outputStream() << "\n\t  "
-                         << SRI.getSymbolInfoAsString(LTOSym, Options);
-        }
-      }
-      outputStream() << "\n";
-    }
-  }
-}
-
 void TextLayoutPrinter::printOffsetHelper(bool HasOffset,
                                           std::function<void()> F) const {
   if (!HasOffset) {

lib/LinkerWrapper/GnuLdDriver.cpp

@@ -1333,6 +1333,11 @@ bool GnuLdDriver::processOptions(llvm::opt::InputArgList &Args) {
     Config.options().setArchiveMemberReportFile(A->getValue());
   }
 
+  // --emit-symbol-resolution-report=<file>
+  if (llvm::opt::Arg *A = Args.getLastArg(T::SymbolResolutionReportFile)) {
+    Config.options().setSymbolResolutionReportFile(A->getValue());
+  }
+
   if (Args.hasArg(T::use_old_rule_matching))
     Config.options().setUseOldRuleMatching(true);
 
@@ -2037,6 +2042,8 @@ bool GnuLdDriver::doLink(llvm::opt::InputArgList &Args,
         linkStatus = linker.link();
       // llvm::errs() << "link: linkStatus: " << linkStatus << "\n";
       linker.printLayout();
+      if (linkStatus && Config.options().shouldEmitSymbolResolutionReport())
+        linkStatus &= linker.emitSymbolResolutionReport();
     }
     if (!linkStatus || Config.options().getRecordInputFiles())
       handleReproduce<T>(Args, actions, true);

lib/Object/ObjectLinker.cpp

@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 #include "eld/Object/ObjectLinker.h"
 #include "eld/BranchIsland/BranchIslandFactory.h"
+#include "eld/Config/GeneralOptions.h"
 #include "eld/Config/LinkerConfig.h"
 #include "eld/Core/LinkerScript.h"
 #include "eld/Core/Module.h"
@@ -52,6 +53,7 @@
 #include "eld/Script/InputSectDesc.h"
 #include "eld/Script/OutputSectData.h"
 #include "eld/Script/OutputSectDesc.h"
+#include "eld/Script/Plugin.h"
 #include "eld/Script/ScriptFile.h"
 #include "eld/Script/ScriptReader.h"
 #include "eld/Script/ScriptSymbol.h"
@@ -62,7 +64,10 @@
 #include "eld/Support/StringRefUtils.h"
 #include "eld/Support/Utils.h"
 #include "eld/SymbolResolver/IRBuilder.h"
+#include "eld/SymbolResolver/LDSymbol.h"
+#include "eld/SymbolResolver/NamePool.h"
 #include "eld/SymbolResolver/ResolveInfo.h"
+#include "eld/SymbolResolver/SymbolResolutionInfo.h"
 #include "eld/Target/GNULDBackend.h"
 #include "eld/Target/LDFileFormat.h"
 #include "eld/Target/Relocator.h"
@@ -85,6 +90,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include <chrono>
 #include <mutex>
+#include <optional>
 #include <sstream>
 #include <unordered_set>
 
@@ -160,6 +166,11 @@ bool ObjectLinker::emitArchiveMemberReport(llvm::StringRef Filename) const {
                                       ThisConfig.getDiagEngine());
 }
 
+bool ObjectLinker::emitSymbolResolutionReport(llvm::StringRef Filename) const {
+  return ThisModule->getNamePool().getSRI().emitSymbolResolutionReport(
+      *ThisModule, Filename);
+}
+
 /// initStdSections - initialize standard sections
 bool ObjectLinker::initStdSections() {
   ObjectBuilder Builder(ThisConfig, *ThisModule);

lib/SymbolResolver/IRBuilder.cpp

@@ -234,8 +234,7 @@ LDSymbol *IRBuilder::addSymbolFromObject(
     return InputSym;
   }
 
-  if (ThisModule.getLayoutInfo() &&
-      ThisModule.getLayoutInfo()->showSymbolResolution())
+  if (ThisModule.getConfig().options().shouldEmitSymbolResolutionReport())
     NP.getSRI().recordSymbolInfo(InputSym, SymInfo);
 
   bool S = NP.insertNonLocalSymbol(InputSymbolResolveInfo, *InputSym,
@@ -336,8 +335,7 @@ LDSymbol *IRBuilder::addSymbolFromDynObj(
     InputSym->setSectionIndex(Shndx);
     InputSym->setSymbolIndex(SymIdx);
 
-    if (ThisModule.getLayoutInfo() &&
-        ThisModule.getLayoutInfo()->showSymbolResolution())
+    if (ThisModule.getConfig().options().shouldEmitSymbolResolutionReport())
       ThisModule.getNamePool().getSRI().recordSymbolInfo(InputSym, SymInfo);
 
     Resolver::Result ResolvedResult = {nullptr, false, false};
@@ -572,8 +570,7 @@ LDSymbol *IRBuilder::addSymbol<IRBuilder::Force, IRBuilder::Unresolve>(
     OutputSym->setValue(Value, false);
   }
 
-  if (ThisModule.getLayoutInfo() &&
-      ThisModule.getLayoutInfo()->showSymbolResolution()) {
+  if (ThisModule.getConfig().options().shouldEmitSymbolResolutionReport()) {
     SymbolResolutionInfo &SRI = ThisModule.getNamePool().getSRI();
     SRI.recordSymbolInfo(OutputSym,
                          SymbolInfo{Input, Size, Binding, Type, Visibility,