[NewPM][LTO] Use new pass manager with ENABLE_EXPERIMENTAL_NEW_PASS_MANAGER

[aeubanks]

Summary

This changes the default value of llvm::lto::Config::UseNewPM to be the
value of the CMake variable ENABLE_EXPERIMENTAL_NEW_PASS_MANAGER, rather
than always false.

So anybody building with -DENABLE_EXPERIMENTAL_NEW_PASS_MANAGER=ON will
now use the new pass manager via these interfaces. This matches Clang.

[aeubanks]

(not for review yet)

[MaskRay]

In LLD, we generally don't recommend configure-time default values. We expect the driver to handle platform differences (e.g. default -pie) and pass the proper options to LLD. We can default to true and let the clang driver pass --no-lto-new-pass-manager to LLD if needed.

[mehdi_amini]

@MaskRay this is an internal thing, not something we expect to pass in from the driver based on the platform or anything.

[aeubanks]

Mehdi's point makes sense, this is internal LLVM stuff that's not platform specific.
But if I were to pass arguments to LLD in the Clang driver, where would that be?

[aeubanks]

Was split into multiple changes

lld/COFF/Driver.cpp

 #include "lld/Common/ErrorHandler.h"
 #include "lld/Common/Filesystem.h"
 #include "lld/Common/Memory.h"
 #include "lld/Common/Timer.h"
 #include "lld/Common/Version.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/BinaryFormat/Magic.h"
+#include "llvm/Config/llvm-config.h"
 #include "llvm/LTO/LTO.h"
 #include "llvm/Object/ArchiveWriter.h"
 #include "llvm/Object/COFFImportFile.h"
 #include "llvm/Object/COFFModuleDefinition.h"
 #include "llvm/Object/WindowsMachineFlag.h"
 #include "llvm/Option/Arg.h"
 #include "llvm/Option/ArgList.h"
 #include "llvm/Option/Option.h"
void LinkerDriver::link(ArrayRef<const char *> argsArr) {
   if (auto *arg = args.getLastArg(OPT_implib))
     config->implib = arg->getValue();
 
   // Handle /opt.
   bool doGC = debug == DebugKind::None || args.hasArg(OPT_profile);
   unsigned icfLevel =
       args.hasArg(OPT_profile) ? 0 : 1; // 0: off, 1: limited, 2: on
   unsigned tailMerge = 1;
-  bool ltoNewPM = false;
+  bool ltoNewPM = LLVM_ENABLE_NEW_PASS_MANAGER;
   bool ltoDebugPM = false;
   for (auto *arg : args.filtered(OPT_opt)) {
     std::string str = StringRef(arg->getValue()).lower();
     SmallVector<StringRef, 1> vec;
     StringRef(str).split(vec, ',');
     for (StringRef s : vec) {
       if (s == "ref") {
         doGC = true;

lld/ELF/Driver.cpp

 #include "lld/Common/Filesystem.h"
 #include "lld/Common/Memory.h"
 #include "lld/Common/Strings.h"
 #include "lld/Common/TargetOptionsCommandFlags.h"
 #include "lld/Common/Version.h"
 #include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringSwitch.h"
+#include "llvm/Config/llvm-config.h"
 #include "llvm/LTO/LTO.h"
 #include "llvm/Remarks/HotnessThresholdParser.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Compression.h"
 #include "llvm/Support/GlobPattern.h"
 #include "llvm/Support/LEB128.h"
 #include "llvm/Support/Parallel.h"
 #include "llvm/Support/Path.h"
static void readConfigs(opt::InputArgList &args) {
   config->ignoreFunctionAddressEquality =
       args.hasArg(OPT_ignore_function_address_equality);
   config->init = args.getLastArgValue(OPT_init, "_init");
   config->ltoAAPipeline = args.getLastArgValue(OPT_lto_aa_pipeline);
   config->ltoCSProfileGenerate = args.hasArg(OPT_lto_cs_profile_generate);
   config->ltoCSProfileFile = args.getLastArgValue(OPT_lto_cs_profile_file);
   config->ltoDebugPassManager = args.hasArg(OPT_lto_debug_pass_manager);
   config->ltoEmitAsm = args.hasArg(OPT_lto_emit_asm);
-  config->ltoNewPassManager = args.hasFlag(OPT_lto_new_pass_manager,
-                                           OPT_no_lto_new_pass_manager, false);
+  config->ltoNewPassManager =
+      args.hasFlag(OPT_lto_new_pass_manager, OPT_no_lto_new_pass_manager,
+                   LLVM_ENABLE_NEW_PASS_MANAGER);
   config->ltoNewPmPasses = args.getLastArgValue(OPT_lto_newpm_passes);
   config->ltoWholeProgramVisibility =
       args.hasFlag(OPT_lto_whole_program_visibility,
                    OPT_no_lto_whole_program_visibility, false);
   config->ltoo = args::getInteger(args, OPT_lto_O, 2);
   config->ltoObjPath = args.getLastArgValue(OPT_lto_obj_path_eq);
   config->ltoPartitions = args::getInteger(args, OPT_lto_partitions, 1);
   config->ltoSampleProfile = args.getLastArgValue(OPT_lto_sample_profile);

lld/wasm/Driver.cpp

 #include "lld/Common/Args.h"
 #include "lld/Common/ErrorHandler.h"
 #include "lld/Common/Filesystem.h"
 #include "lld/Common/Memory.h"
 #include "lld/Common/Reproduce.h"
 #include "lld/Common/Strings.h"
 #include "lld/Common/Version.h"
 #include "llvm/ADT/Twine.h"
+#include "llvm/Config/llvm-config.h"
 #include "llvm/Object/Wasm.h"
 #include "llvm/Option/Arg.h"
 #include "llvm/Option/ArgList.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Host.h"
 #include "llvm/Support/Parallel.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/Process.h"
static void readConfigs(opt::InputArgList &args) {
   config->growableTable = args.hasArg(OPT_growable_table);
   errorHandler().fatalWarnings =
       args.hasFlag(OPT_fatal_warnings, OPT_no_fatal_warnings, false);
   config->importMemory = args.hasArg(OPT_import_memory);
   config->sharedMemory = args.hasArg(OPT_shared_memory);
   config->importTable = args.hasArg(OPT_import_table);
   config->ltoo = args::getInteger(args, OPT_lto_O, 2);
   config->ltoPartitions = args::getInteger(args, OPT_lto_partitions, 1);
-  config->ltoNewPassManager = args.hasFlag(OPT_lto_new_pass_manager,
-                                           OPT_lto_no_new_pass_manager, false);
+  config->ltoNewPassManager =
+      args.hasFlag(OPT_lto_new_pass_manager, OPT_lto_no_new_pass_manager,
+                   LLVM_ENABLE_NEW_PASS_MANAGER);
   config->ltoDebugPassManager = args.hasArg(OPT_lto_debug_pass_manager);
   config->mapFile = args.getLastArgValue(OPT_Map);
   config->optimize = args::getInteger(args, OPT_O, 0);
   config->outputFile = args.getLastArgValue(OPT_o);
   config->relocatable = args.hasArg(OPT_relocatable);
   config->gcSections =
       args.hasFlag(OPT_gc_sections, OPT_no_gc_sections, !config->relocatable);
   config->mergeDataSegments =

llvm/include/llvm/LTO/Config.h

 // configure LTO.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_LTO_CONFIG_H
 #define LLVM_LTO_CONFIG_H
 
 #include "llvm/ADT/DenseSet.h"
+#include "llvm/Config/llvm-config.h"
 #include "llvm/IR/DiagnosticInfo.h"
 #include "llvm/IR/GlobalValue.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/Passes/PassBuilder.h"
 #include "llvm/Support/CodeGen.h"
 #include "llvm/Target/TargetOptions.h"
 
 #include <functional>
struct Config {
   Optional<Reloc::Model> RelocModel = Reloc::PIC_;
   Optional<CodeModel::Model> CodeModel = None;
   CodeGenOpt::Level CGOptLevel = CodeGenOpt::Default;
   CodeGenFileType CGFileType = CGFT_ObjectFile;
   unsigned OptLevel = 2;
   bool DisableVerify = false;
 
   /// Use the new pass manager
-  bool UseNewPM = false;
+  bool UseNewPM = LLVM_ENABLE_NEW_PASS_MANAGER;
 
   /// Flag to indicate that the optimizer should not assume builtins are present
   /// on the target.
   bool Freestanding = false;
 
   /// Disable entirely the optimizer, including importing for ThinLTO
   bool CodeGenOnly = false;
 

llvm/tools/gold/gold-plugin.cpp

 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ADT/Statistic.h"
 #include "llvm/Bitcode/BitcodeReader.h"
 #include "llvm/Bitcode/BitcodeWriter.h"
 #include "llvm/CodeGen/CommandFlags.h"
 #include "llvm/Config/config.h" // plugin-api.h requires HAVE_STDINT_H
+#include "llvm/Config/llvm-config.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DiagnosticPrinter.h"
 #include "llvm/LTO/Caching.h"
 #include "llvm/LTO/LTO.h"
 #include "llvm/Object/Error.h"
 #include "llvm/Remarks/HotnessThresholdParser.h"
 #include "llvm/Support/CachePruning.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Host.h"
 #include "llvm/Support/ManagedStatic.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/TargetSelect.h"
 #include "llvm/Support/Threading.h"
 #include "llvm/Support/raw_ostream.h"
 #include <list>
 #include <map>
 #include <plugin-api.h>
 #include <string>
 #include <system_error>
 #include <utility>
 #include <vector>
 
 // FIXME: remove this declaration when we stop maintaining Ubuntu Quantal and
 // Precise and Debian Wheezy (binutils 2.23 is required)
 #define LDPO_PIE 3
#endif
   static std::string cache_policy;
   // Additional options to pass into the code generator.
   // Note: This array will contain all plugin options which are not claimed
   // as plugin exclusive to pass to the code generator.
   static std::vector<const char *> extra;
   // Sample profile file path
   static std::string sample_profile;
   // New pass manager
-  static bool new_pass_manager = false;
+  static bool new_pass_manager = LLVM_ENABLE_NEW_PASS_MANAGER;
   // Debug new pass manager
   static bool debug_pass_manager = false;
   // Directory to store the .dwo files.
   static std::string dwo_dir;
   /// Statistics output filename.
   static std::string stats_file;
   // Asserts that LTO link has whole program visibility
   static bool whole_program_visibility = false;

llvm/tools/llvm-lto2/llvm-lto2.cpp

 //
 // This program is intended to eventually replace llvm-lto which uses the legacy
 // LTO interface.
 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Bitcode/BitcodeReader.h"
 #include "llvm/CodeGen/CommandFlags.h"
+#include "llvm/Config/llvm-config.h"
 #include "llvm/IR/DiagnosticPrinter.h"
 #include "llvm/LTO/Caching.h"
 #include "llvm/LTO/LTO.h"
 #include "llvm/Passes/PassPlugin.h"
 #include "llvm/Remarks/HotnessThresholdParser.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/InitLLVM.h"

 static cl::opt<bool>
     RunCSIRInstr("lto-cspgo-gen",
                  cl::desc("Run PGO context sensitive IR instrumentation"),
                  cl::init(false), cl::Hidden);
 
 static cl::opt<bool>
     UseNewPM("use-new-pm",
              cl::desc("Run LTO passes using the new pass manager"),
-             cl::init(false), cl::Hidden);
+             cl::init(LLVM_ENABLE_NEW_PASS_MANAGER), cl::Hidden);
 
 static cl::opt<bool>
     DebugPassManager("debug-pass-manager", cl::init(false), cl::Hidden,
                      cl::desc("Print pass management debugging information"));
 
 static cl::opt<std::string>
     StatsFile("stats-file", cl::desc("Filename to write statistics to"));