[llvm-objcopy][NFC] Use StringSaver for --keep-global-symbols

[rupprecht]

Summary

Use StringSaver/BumpPtrAlloc when parsing lines from --keep-global-symbols files. This allows us to consistently use StringRef for driver options, which avoids copying the full strings for each object copied, as well as simplifies part of D57517.

[evgeny777]

LGTM

llvm/tools/llvm-objcopy/CopyConfig.h

 //===- CopyConfig.h -------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_TOOLS_LLVM_OBJCOPY_COPY_CONFIG_H
 #define LLVM_TOOLS_LLVM_OBJCOPY_COPY_CONFIG_H
 
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/Support/Allocator.h"
 // Necessary for llvm::DebugCompressionType::None
 #include "llvm/Target/TargetOptions.h"
-#include <string>
 #include <vector>
 
 namespace llvm {
 namespace objcopy {
 
 // This type keeps track of the machine info for various architectures. This
 // lets us map architecture names to ELF types and the e_machine value of the
 // ELF file.
struct CopyConfig {
   std::vector<StringRef> KeepSection;
   std::vector<StringRef> OnlySection;
   std::vector<StringRef> SymbolsToGlobalize;
   std::vector<StringRef> SymbolsToKeep;
   std::vector<StringRef> SymbolsToLocalize;
   std::vector<StringRef> SymbolsToRemove;
   std::vector<StringRef> SymbolsToWeaken;
   std::vector<StringRef> ToRemove;
-  std::vector<std::string> SymbolsToKeepGlobal;
+  std::vector<StringRef> SymbolsToKeepGlobal;
 
   // Map options
   StringMap<SectionRename> SectionsToRename;
   StringMap<SectionFlagsUpdate> SetSectionFlags;
   StringMap<StringRef> SymbolsToRename;
 
   // Boolean options
   bool DeterministicArchives = true;
struct CopyConfig {
   DebugCompressionType CompressionType = DebugCompressionType::None;
 };
 
 // Configuration for the overall invocation of this tool. When invoked as
 // objcopy, will always contain exactly one CopyConfig. When invoked as strip,
 // will contain one or more CopyConfigs.
 struct DriverConfig {
   SmallVector<CopyConfig, 1> CopyConfigs;
+  BumpPtrAllocator Alloc;
 };
 
 // ParseObjcopyOptions returns the config and sets the input arguments. If a
 // help flag is set then ParseObjcopyOptions will print the help messege and
 // exit.
 DriverConfig parseObjcopyOptions(ArrayRef<const char *> ArgsArr);
 
 // ParseStripOptions returns the config and sets the input arguments. If a
 // help flag is set then ParseStripOptions will print the help messege and
 // exit.
 DriverConfig parseStripOptions(ArrayRef<const char *> ArgsArr);
 
 } // namespace objcopy
 } // namespace llvm
 
 #endif

llvm/tools/llvm-objcopy/CopyConfig.cpp

 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Object/ELFTypes.h"
 #include "llvm/Option/Arg.h"
 #include "llvm/Option/ArgList.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Compression.h"
 #include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/StringSaver.h"
 #include <memory>
-#include <string>
 
 namespace llvm {
 namespace objcopy {
 
 namespace {
 enum ObjcopyID {
   OBJCOPY_INVALID = 0, // This is not an option ID.
 #define OPTION(PREFIX, NAME, ID, KIND, GROUP, ALIAS, ALIASARGS, FLAGS, PARAM,  \

 
 static const MachineInfo &getOutputFormatMachineInfo(StringRef Format) {
   auto Iter = OutputFormatMap.find(Format);
   if (Iter == std::end(OutputFormatMap))
     error("Invalid output format: '" + Format + "'");
   return Iter->getValue();
 }
 
-static void addGlobalSymbolsFromFile(std::vector<std::string> &Symbols,
+static void addGlobalSymbolsFromFile(std::vector<StringRef> &Symbols,
+                                     BumpPtrAllocator &Alloc,
                                      StringRef Filename) {
+  StringSaver Saver(Alloc);
   SmallVector<StringRef, 16> Lines;
   auto BufOrErr = MemoryBuffer::getFile(Filename);
   if (!BufOrErr)
     reportError(Filename, BufOrErr.getError());
 
   BufOrErr.get()->getBuffer().split(Lines, '\n');
   for (StringRef Line : Lines) {
     // Ignore everything after '#', trim whitespace, and only add the symbol if
     // it's not empty.
     auto TrimmedLine = Line.split('#').first.trim();
     if (!TrimmedLine.empty())
-      Symbols.push_back(TrimmedLine.str());
+      Symbols.push_back(Saver.save(TrimmedLine));
   }
 }
 
 // ParseObjcopyOptions returns the config and sets the input arguments. If a
 // help flag is set then ParseObjcopyOptions will print the help messege and
 // exit.
 DriverConfig parseObjcopyOptions(ArrayRef<const char *> ArgsArr) {
+  DriverConfig DC;
   ObjcopyOptTable T;
   unsigned MissingArgumentIndex, MissingArgumentCount;
   llvm::opt::InputArgList InputArgs =
       T.ParseArgs(ArgsArr, MissingArgumentIndex, MissingArgumentCount);
 
   if (InputArgs.size() == 0) {
     T.PrintHelp(errs(), "llvm-objcopy input [output]", "objcopy tool");
     exit(1);
DriverConfig parseObjcopyOptions(ArrayRef<const char *> ArgsArr) {
   Config.KeepFileSymbols = InputArgs.hasArg(OBJCOPY_keep_file_symbols);
   Config.DecompressDebugSections =
       InputArgs.hasArg(OBJCOPY_decompress_debug_sections);
   for (auto Arg : InputArgs.filtered(OBJCOPY_localize_symbol))
     Config.SymbolsToLocalize.push_back(Arg->getValue());
   for (auto Arg : InputArgs.filtered(OBJCOPY_keep_global_symbol))
     Config.SymbolsToKeepGlobal.push_back(Arg->getValue());
   for (auto Arg : InputArgs.filtered(OBJCOPY_keep_global_symbols))
-    addGlobalSymbolsFromFile(Config.SymbolsToKeepGlobal, Arg->getValue());
+    addGlobalSymbolsFromFile(Config.SymbolsToKeepGlobal, DC.Alloc,
+                             Arg->getValue());
   for (auto Arg : InputArgs.filtered(OBJCOPY_globalize_symbol))
     Config.SymbolsToGlobalize.push_back(Arg->getValue());
   for (auto Arg : InputArgs.filtered(OBJCOPY_weaken_symbol))
     Config.SymbolsToWeaken.push_back(Arg->getValue());
   for (auto Arg : InputArgs.filtered(OBJCOPY_strip_symbol))
     Config.SymbolsToRemove.push_back(Arg->getValue());
   for (auto Arg : InputArgs.filtered(OBJCOPY_keep_symbol))
     Config.SymbolsToKeep.push_back(Arg->getValue());
 
   Config.DeterministicArchives = InputArgs.hasFlag(
       OBJCOPY_enable_deterministic_archives,
       OBJCOPY_disable_deterministic_archives, /*default=*/true);
 
   Config.PreserveDates = InputArgs.hasArg(OBJCOPY_preserve_dates);
 
   if (Config.DecompressDebugSections &&
       Config.CompressionType != DebugCompressionType::None) {
     error("Cannot specify --compress-debug-sections at the same time as "
           "--decompress-debug-sections at the same time");
   }
 
   if (Config.DecompressDebugSections && !zlib::isAvailable())
     error("LLVM was not compiled with LLVM_ENABLE_ZLIB: cannot decompress.");
 
-  DriverConfig DC;
   DC.CopyConfigs.push_back(std::move(Config));
   return DC;
 }
 
 // ParseStripOptions returns the config and sets the input arguments. If a
 // help flag is set then ParseStripOptions will print the help messege and
 // exit.
 DriverConfig parseStripOptions(ArrayRef<const char *> ArgsArr) {