[lld][COFF] Use .contains rather than .count for set membership. NFC (#177067)

Also converted a couple of `std::set` to
`llvm::StringSet`/`llvm::SmallSet`.

This matches the usage in the other linker backends.

See #176610

lld/COFF/Config.h

@@ -15,12 +15,12 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/StringSet.h"
 #include "llvm/Object/COFF.h"
 #include "llvm/Support/CachePruning.h"
 #include "llvm/Support/VirtualFileSystem.h"
 #include <cstdint>
 #include <map>
-#include <set>
 #include <string>
 
 namespace lld::coff {
@@ -155,14 +155,14 @@ struct Configuration {
   // Symbols in this set are considered as live by the garbage collector.
   std::vector<Symbol *> gcroot;
 
-  std::set<std::string> noDefaultLibs;
+  llvm::StringSet<> noDefaultLibs;
   bool noDefaultLibAll = false;
 
   // True if we are creating a DLL.
   bool dll = false;
   StringRef implib;
   bool noimplib = false;
-  std::set<std::string> delayLoads;
+  llvm::StringSet<> delayLoads;
   std::map<std::string, int> dllOrder;
   Symbol *arm64ECIcallHelper = nullptr;
 

lld/COFF/Driver.cpp

@@ -23,6 +23,7 @@
 #include "lld/Common/Timer.h"
 #include "lld/Common/Version.h"
 #include "llvm/ADT/IntrusiveRefCntPtr.h"
+#include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/BinaryFormat/Magic.h"
 #include "llvm/Config/llvm-config.h"
@@ -715,7 +716,7 @@ std::optional<StringRef> LinkerDriver::findLibIfNew(StringRef filename) {
     return std::nullopt;
 
   StringRef path = findLib(filename);
-  if (ctx.config.noDefaultLibs.count(path.lower()))
+  if (ctx.config.noDefaultLibs.contains(path.lower()))
     return std::nullopt;
 
   if (std::optional<sys::fs::UniqueID> id = getUniqueID(path))
@@ -864,9 +865,9 @@ void LinkerDriver::addWinSysRootLibSearchPaths() {
 
   // Libraries specified by `/nodefaultlib:` may not be found in incomplete
   // search paths before lld infers a machine type from input files.
-  std::set<std::string> noDefaultLibs;
-  for (const std::string &path : ctx.config.noDefaultLibs)
-    noDefaultLibs.insert(findLib(path).lower());
+  llvm::StringSet<> noDefaultLibs;
+  for (auto &iter : ctx.config.noDefaultLibs)
+    noDefaultLibs.insert(findLib(iter.first()).lower());
   ctx.config.noDefaultLibs = noDefaultLibs;
 }
 
@@ -1153,7 +1154,7 @@ void LinkerDriver::parseOrderFile(StringRef arg) {
     if (ctx.config.machine == I386 && !isDecorated(s))
       s = "_" + s;
 
-    if (set.count(s) == 0) {
+    if (!set.contains(s)) {
       if (ctx.config.warnMissingOrderSymbol)
         Warn(ctx) << "/order:" << arg << ": missing symbol: " << s
                   << " [LNK4037]";
@@ -2284,7 +2285,7 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
   if (errCount(ctx))
     return;
 
-  std::set<sys::fs::UniqueID> wholeArchives;
+  SmallSet<sys::fs::UniqueID, 0> wholeArchives;
   for (auto *arg : args.filtered(OPT_wholearchive_file))
     if (std::optional<StringRef> path = findFile(arg->getValue()))
       if (std::optional<sys::fs::UniqueID> id = getUniqueID(*path))
@@ -2298,7 +2299,7 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
     if (args.hasArg(OPT_wholearchive_flag))
       return true;
     if (std::optional<sys::fs::UniqueID> id = getUniqueID(path))
-      return wholeArchives.count(*id);
+      return wholeArchives.contains(*id);
     return false;
   };
 

lld/COFF/MinGW.cpp

@@ -150,7 +150,8 @@ bool AutoExporter::shouldExport(Defined *sym) const {
   // disallow import symbols.
   if (!isa<DefinedRegular>(sym) && !isa<DefinedCommon>(sym))
     return false;
-  if (excludeSymbols.count(sym->getName()) || manualExcludeSymbols.count(sym->getName()))
+  if (excludeSymbols.contains(sym->getName()) ||
+      manualExcludeSymbols.contains(sym->getName()))
     return false;
 
   for (StringRef prefix : excludeSymbolPrefixes.keys())
@@ -174,10 +175,10 @@ bool AutoExporter::shouldExport(Defined *sym) const {
   // Drop the file extension.
   libName = libName.substr(0, libName.rfind('.'));
   if (!libName.empty())
-    return !excludeLibs.count(libName);
+    return !excludeLibs.contains(libName);
 
   StringRef fileName = sys::path::filename(sym->getFile()->getName());
-  return !excludeObjects.count(fileName);
+  return !excludeObjects.contains(fileName);
 }
 
 void lld::coff::writeDefFile(COFFLinkerContext &ctx, StringRef name,

lld/COFF/SymbolTable.cpp

@@ -381,7 +381,7 @@ void SymbolTable::reportProblemSymbols(
     return;
 
   for (Symbol *b : ctx.config.gcroot) {
-    if (undefs.count(b))
+    if (undefs.contains(b))
       errorOrWarn(ctx) << "<root>: undefined symbol: " << printSymbol(b);
     if (localImports)
       if (Symbol *imp = localImports->lookup(b))
@@ -399,7 +399,7 @@ void SymbolTable::reportProblemSymbols(
       ++symIndex;
       if (!sym)
         continue;
-      if (undefs.count(sym)) {
+      if (undefs.contains(sym)) {
         auto [it, inserted] = firstDiag.try_emplace(sym, undefDiags.size());
         if (inserted)
           undefDiags.push_back({sym, {{file, symIndex}}});

lld/COFF/Writer.cpp

@@ -1330,7 +1330,7 @@ void Writer::createImportTables() {
     if (file->impSym && !isa<DefinedImportData>(file->impSym))
       Fatal(ctx) << file->symtab.printSymbol(file->impSym) << " was replaced";
     DefinedImportData *impSym = cast_or_null<DefinedImportData>(file->impSym);
-    if (ctx.config.delayLoads.count(StringRef(file->dllName).lower())) {
+    if (ctx.config.delayLoads.contains(StringRef(file->dllName).lower())) {
       if (!file->thunkSym)
         Fatal(ctx) << "cannot delay-load " << toString(file)
                    << " due to import of data: "