[LLD][gold] Add -plugin-opt=no-new-pass-manager

[MaskRay]

Summary

-DENABLE_EXPERIMENTAL_NEW_PASS_MANAGER=on configured LLD and LLVMgold.so
will use the new pass manager by default. Add an option to
use the legacy pass manager. This will also be used by the Clang driver
when -fno-new-pass-manager (D92915) / -fno-experimental-new-pass-manager is set.

[MaskRay]

@tejohnson Are you fine with -plugin-opt=no-new-pass-manager? 😃

[tejohnson]

LGTM with a minor fix: Patch description has a typo, mentions -fno-pass-manager, I think this should be -fno-new-pass-manager?

lld/ELF/Options.td

 def plugin_opt_emit_asm: F<"plugin-opt=emit-asm">,
   Alias<lto_emit_asm>, HelpText<"Alias for --lto-emit-asm">;
 def plugin_opt_emit_llvm: F<"plugin-opt=emit-llvm">;
 def: J<"plugin-opt=jobs=">, Alias<thinlto_jobs>, HelpText<"Alias for --thinlto-jobs">;
 def: J<"plugin-opt=lto-partitions=">, Alias<lto_partitions>, HelpText<"Alias for --lto-partitions">;
 def plugin_opt_mcpu_eq: J<"plugin-opt=mcpu=">;
 def: F<"plugin-opt=new-pass-manager">,
   Alias<lto_new_pass_manager>, HelpText<"Alias for --lto-new-pass-manager">;
+def: F<"plugin-opt=no-new-pass-manager">,
+  Alias<no_lto_new_pass_manager>, HelpText<"Alias for --no-lto-new-pass-manager">;
 def: F<"plugin-opt=cs-profile-generate">,
   Alias<lto_cs_profile_generate>, HelpText<"Alias for --lto-cs-profile-generate">;
 def: J<"plugin-opt=cs-profile-path=">,
   Alias<lto_cs_profile_file>, HelpText<"Alias for --lto-cs-profile-file">;
 def: J<"plugin-opt=obj-path=">,
   Alias<lto_obj_path_eq>,
   HelpText<"Alias for --lto-obj-path=">;
 def: J<"plugin-opt=opt-remarks-filename=">,

lld/test/ELF/lto/new-pass-manager.ll

 ; REQUIRES: x86
 ; RUN: opt -module-summary %s -o %t.o
 
 ; Test new-pass-manager and debug-pass-manager option
 ; RUN: ld.lld --plugin-opt=new-pass-manager --plugin-opt=debug-pass-manager -o /dev/null %t.o 2>&1 | FileCheck %s
 ; RUN: ld.lld --plugin-opt=new-pass-manager --lto-debug-pass-manager -o /dev/null %t.o 2>&1 | FileCheck %s
 ; RUN: ld.lld --lto-new-pass-manager --plugin-opt=debug-pass-manager -o /dev/null %t.o 2>&1 | FileCheck %s
 ; RUN: ld.lld --lto-new-pass-manager --lto-debug-pass-manager -o /dev/null %t.o 2>&1 | FileCheck %s
 ; RUN: ld.lld --lto-new-pass-manager --no-lto-new-pass-manager --lto-debug-pass-manager -o /dev/null %t.o 2>&1 | FileCheck %s --check-prefix=LEGACY
+; RUN: ld.lld --plugin-opt=no-new-pass-manager --plugin-opt=debug-pass-manager -o /dev/null %t.o 2>&1 | FileCheck %s --check-prefix=LEGACY
 
 ; CHECK: Starting llvm::Module pass manager run
 ; CHECK: Finished llvm::Module pass manager run
 ; LEGACY-NOT: Starting llvm::Module pass manager run
 
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"

llvm/test/tools/gold/X86/new-pm.ll

 ; Test plugin options new-pass-manager and debug-pass-manager
 ; RUN: opt -module-summary %s -o %t.o
 
 ; RUN: %gold -m elf_x86_64 -plugin %llvmshlibdir/LLVMgold%shlibext \
 ; RUN:     --plugin-opt=thinlto \
 ; RUN:     --plugin-opt=new-pass-manager \
 ; RUN:     --plugin-opt=debug-pass-manager \
 ; RUN:     --plugin-opt=cache-dir=%t.cache \
 ; RUN:     -o %t2.o %t.o 2>&1 | FileCheck %s
 
 ; CHECK: Starting llvm::Module pass manager run
 
+;; --plugin-opt=debug-pass-manager is a no-op for the legacy pass manager.
+; RUN: %gold -m elf_x86_64 -plugin %llvmshlibdir/LLVMgold%shlibext \
+; RUN:     --plugin-opt=thinlto \
+; RUN:     --plugin-opt=no-new-pass-manager --plugin-opt=debug-pass-manager \
+; RUN:     -o /dev/null %t.o 2>&1 | count 0
+
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
 define void @globalfunc() #0 {
 entry:
   ret void
 }

llvm/tools/gold/gold-plugin.cpp

static void process_plugin_option(const char *opt_)
     } else if (opt.consume_front("sample-profile=")) {
       sample_profile = std::string(opt);
     } else if (opt == "cs-profile-generate") {
       cs_pgo_gen = true;
     } else if (opt.consume_front("cs-profile-path=")) {
       cs_profile_path = std::string(opt);
     } else if (opt == "new-pass-manager") {
       new_pass_manager = true;
+    } else if (opt == "no-new-pass-manager") {
+      new_pass_manager = false;
     } else if (opt == "debug-pass-manager") {
       debug_pass_manager = true;
     } else if (opt == "whole-program-visibility") {
       whole_program_visibility = true;
     } else if (opt.consume_front("dwo_dir=")) {
       dwo_dir = std::string(opt);
     } else if (opt.consume_front("opt-remarks-filename=")) {
       RemarksFilename = std::string(opt);