[ELF] Replace SymbolTable::forEachSymbol with iterator_range symbols()

D62381 introduced forEachSymbol(). It seems that many call sites cannot
be parallelized because the body shared some states. Replace
forEachSymbol with iterator_range<filter_iterator<...>> symbols() to
simplify code and improve debuggability (std::function calls take some
frames).

It also allows us to use early return to simplify code added in D69650.

Reviewed By: grimar

Differential Revision: https://reviews.llvm.org/D70505

diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp
index b13bb5e..a098725 100644 (file)
--- a/lld/ELF/Driver.cpp
+++ b/lld/ELF/Driver.cpp
@@ -1408,13 +1408,13 @@ static void handleUndefinedGlob(StringRef arg) {
   }
 
   std::vector<Symbol *> syms;
-  symtab->forEachSymbol([&](Symbol *sym) {
+  for (Symbol *sym : symtab->symbols()) {
     // Calling Sym->fetch() from here is not safe because it may
     // add new symbols to the symbol table, invalidating the
     // current iterator. So we just keep a note.
     if (pat->match(sym->getName()))
       syms.push_back(sym);
-  });
+  }
 
   for (Symbol *sym : syms)
     handleUndefined(sym);
@@ -1440,10 +1440,10 @@ static void handleLibcall(StringRef name) {
 // result, the passes after the symbol resolution won't see any
 // symbols of type CommonSymbol.
 static void replaceCommonSymbols() {
-  symtab->forEachSymbol([](Symbol *sym) {
+  for (Symbol *sym : symtab->symbols()) {
     auto *s = dyn_cast<CommonSymbol>(sym);
     if (!s)
-      return;
+      continue;
 
     auto *bss = make<BssSection>("COMMON", s->size, s->alignment);
     bss->file = s->file;
@@ -1451,7 +1451,7 @@ static void replaceCommonSymbols() {
     inputSections.push_back(bss);
     s->replace(Defined{s->file, s->getName(), s->binding, s->stOther, s->type,
                        /*value=*/0, s->size, bss});
-  });
+  }
 }
 
 // If all references to a DSO happen to be weak, the DSO is not added
@@ -1459,15 +1459,15 @@ static void replaceCommonSymbols() {
 // created from the DSO. Otherwise, they become dangling references
 // that point to a non-existent DSO.
 static void demoteSharedSymbols() {
-  symtab->forEachSymbol([](Symbol *sym) {
+  for (Symbol *sym : symtab->symbols()) {
     auto *s = dyn_cast<SharedSymbol>(sym);
     if (!s || s->getFile().isNeeded)
-      return;
+      continue;
 
     bool used = s->used;
     s->replace(Undefined{nullptr, s->getName(), STB_WEAK, s->stOther, s->type});
     s->used = used;
-  });
+  }
 }
 
 // The section referred to by `s` is considered address-significant. Set the
@@ -1503,10 +1503,9 @@ static void findKeepUniqueSections(opt::InputArgList &args) {
 
   // Symbols in the dynsym could be address-significant in other executables
   // or DSOs, so we conservatively mark them as address-significant.
-  symtab->forEachSymbol([&](Symbol *sym) {
+  for (Symbol *sym : symtab->symbols())
     if (sym->includeInDynsym())
       markAddrsig(sym);
-  });
 
   // Visit the address-significance table in each object file and mark each
   // referenced symbol as address-significant.

diff --git a/lld/ELF/LTO.cpp b/lld/ELF/LTO.cpp
index 6da4095..524d552 100644 (file)
--- a/lld/ELF/LTO.cpp
+++ b/lld/ELF/LTO.cpp
@@ -145,12 +145,12 @@ BitcodeCompiler::BitcodeCompiler() {
                                        config->ltoPartitions);
 
   // Initialize usedStartStop.
-  symtab->forEachSymbol([&](Symbol *sym) {
+  for (Symbol *sym : symtab->symbols()) {
     StringRef s = sym->getName();
     for (StringRef prefix : {"__start_", "__stop_"})
       if (s.startswith(prefix))
         usedStartStop.insert(s.substr(prefix.size()));
-  });
+  }
 }
 
 BitcodeCompiler::~BitcodeCompiler() = default;

diff --git a/lld/ELF/MarkLive.cpp b/lld/ELF/MarkLive.cpp
index 62fb8fe..bb0105c 100644 (file)
--- a/lld/ELF/MarkLive.cpp
+++ b/lld/ELF/MarkLive.cpp
@@ -219,10 +219,9 @@ template <class ELFT> void MarkLive<ELFT>::run() {
 
   // Preserve externally-visible symbols if the symbols defined by this
   // file can interrupt other ELF file's symbols at runtime.
-  symtab->forEachSymbol([&](Symbol *sym) {
+  for (Symbol *sym : symtab->symbols())
     if (sym->includeInDynsym() && sym->partition == partition)
       markSymbol(sym);
-  });
 
   // If this isn't the main partition, that's all that we need to preserve.
   if (partition != 1) {
@@ -330,11 +329,10 @@ template <class ELFT> void markLive() {
       sec->markLive();
 
     // If a DSO defines a symbol referenced in a regular object, it is needed.
-    symtab->forEachSymbol([](Symbol *sym) {
+    for (Symbol *sym : symtab->symbols())
       if (auto *s = dyn_cast<SharedSymbol>(sym))
         if (s->isUsedInRegularObj && !s->isWeak())
           s->getFile().isNeeded = true;
-    });
     return;
   }
 

diff --git a/lld/ELF/Relocations.cpp b/lld/ELF/Relocations.cpp
index a4fc1ff..80e1de2 100644 (file)
--- a/lld/ELF/Relocations.cpp
+++ b/lld/ELF/Relocations.cpp
@@ -799,10 +799,11 @@ static const Symbol *getAlternativeSpelling(const Undefined &sym,
         break;
       }
     if (!s)
-      symtab->forEachSymbol([&](Symbol *sym) {
-        if (!s && canSuggestExternCForCXX(name, sym->getName()))
+      for (Symbol *sym : symtab->symbols())
+        if (canSuggestExternCForCXX(name, sym->getName())) {
           s = sym;
-      });
+          break;
+        }
     if (s) {
       pre_hint = " to declare ";
       post_hint = " as extern \"C\"?";

diff --git a/lld/ELF/SymbolTable.h b/lld/ELF/SymbolTable.h
index d3be0cb..507af8d 100644 (file)
--- a/lld/ELF/SymbolTable.h
+++ b/lld/ELF/SymbolTable.h
@@ -32,15 +32,19 @@ namespace elf {
 // add*() functions, which are called by input files as they are parsed. There
 // is one add* function per symbol type.
 class SymbolTable {
-public:
-  void wrap(Symbol *sym, Symbol *real, Symbol *wrap);
+  struct FilterOutPlaceholder {
+    bool operator()(Symbol *S) const { return !S->isPlaceholder(); }
+  };
+  using iterator = llvm::filter_iterator<std::vector<Symbol *>::const_iterator,
+                                         FilterOutPlaceholder>;
 
-  void forEachSymbol(llvm::function_ref<void(Symbol *)> fn) {
-    for (Symbol *sym : symVector)
-      if (!sym->isPlaceholder())
-        fn(sym);
+public:
+  llvm::iterator_range<iterator> symbols() const {
+    return llvm::make_filter_range(symVector, FilterOutPlaceholder());
   }
 
+  void wrap(Symbol *sym, Symbol *real, Symbol *wrap);
+
   Symbol *insert(StringRef name);
 
   Symbol *addSymbol(const Symbol &newSym);

diff --git a/lld/ELF/Writer.cpp b/lld/ELF/Writer.cpp
index 3de1230..ebca612 100644 (file)
--- a/lld/ELF/Writer.cpp
+++ b/lld/ELF/Writer.cpp
@@ -1238,10 +1238,9 @@ static DenseMap<const InputSectionBase *, int> buildSectionOrder() {
 
   // We want both global and local symbols. We get the global ones from the
   // symbol table and iterate the object files for the local ones.
-  symtab->forEachSymbol([&](Symbol *sym) {
+  for (Symbol *sym : symtab->symbols())
     if (!sym->isLazy())
       addSym(*sym);
-  });
 
   for (InputFile *file : objectFiles)
     for (Symbol *sym : file->getSymbols())
@@ -1734,8 +1733,8 @@ template <class ELFT> void Writer<ELFT>::finalizeSections() {
   for (Partition &part : partitions)
     finalizeSynthetic(part.ehFrame);
 
-  symtab->forEachSymbol(
-      [](Symbol *s) { s->isPreemptible = computeIsPreemptible(*s); });
+  for (Symbol *sym : symtab->symbols())
+    sym->isPreemptible = computeIsPreemptible(*sym);
 
   // Change values of linker-script-defined symbols from placeholders (assigned
   // by declareSymbols) to actual definitions.
@@ -1769,19 +1768,18 @@ template <class ELFT> void Writer<ELFT>::finalizeSections() {
             return symtab->soNames.count(needed);
           });
 
-    symtab->forEachSymbol([](Symbol *sym) {
+    for (Symbol *sym : symtab->symbols())
       if (sym->isUndefined() && !sym->isWeak())
         if (auto *f = dyn_cast_or_null<SharedFile>(sym->file))
           if (f->allNeededIsKnown)
             error(toString(f) + ": undefined reference to " + toString(*sym));
-    });
   }
 
   // Now that we have defined all possible global symbols including linker-
   // synthesized ones. Visit all symbols to give the finishing touches.
-  symtab->forEachSymbol([](Symbol *sym) {
+  for (Symbol *sym : symtab->symbols()) {
     if (!includeInSymtab(*sym))
-      return;
+      continue;
     if (in.symTab)
       in.symTab->addSymbol(sym);
 
@@ -1791,7 +1789,7 @@ template <class ELFT> void Writer<ELFT>::finalizeSections() {
         if (file->isNeeded && !sym->isUndefined())
           addVerneed(sym);
     }
-  });
+  }
 
   // We also need to scan the dynamic relocation tables of the other partitions
   // and add any referenced symbols to the partition's dynsym.