[LTO] Add --lto-aa-pipeline

[davide]

Summary

--lto-newpm-passes has been in the tree in a while. I used it for a bit and I haven't faced any problems, so I decided to add the last missing bit (--lto-aa-pipeline).
The question (probably for Chandler) is: what's the best way to test this?

[chandlerc]

Yes, this is roughly how I expected the API to be used. Are you running into problems with it?

You might want to name it with a newpm prefix much like the other flag, but I'll leave that mostly up to the LLD folks -- I suspect the local conventions are the most important there.

[davide]

In D20888#446361, @chandlerc wrote:

Yes, this is roughly how I expected the API to be used. Are you running into problems with it?

No, not at all.

You might want to name it with a newpm prefix much like the other flag, but I'll leave that mostly up to the LLD folks -- I suspect the local conventions are the most important there.

Sure, thanks for your review.

[• rafael]

LGTM from the lld side.

Cheers,
Rafael

lld/trunk/ELF/Config.h

 struct Configuration {
   Symbol *EntrySym = nullptr;
   InputFile *FirstElf = nullptr;
   llvm::StringRef DynamicLinker;
   llvm::StringRef Entry;
   llvm::StringRef Emulation;
   llvm::StringRef Fini;
   llvm::StringRef Init;
+  llvm::StringRef LtoAAPipeline;
   llvm::StringRef LtoNewPmPasses;
   llvm::StringRef OutputFile;
   llvm::StringRef SoName;
   llvm::StringRef Sysroot;
   std::string RPath;
   std::vector<llvm::StringRef> DynamicList;
   std::vector<llvm::StringRef> SearchPaths;
   std::vector<llvm::StringRef> Undefined;

lld/trunk/ELF/Driver.cpp

void LinkerDriver::readConfigs(opt::InputArgList &Args) {
   Config->Trace = Args.hasArg(OPT_trace);
   Config->Verbose = Args.hasArg(OPT_verbose);
   Config->WarnCommon = Args.hasArg(OPT_warn_common);
 
   Config->DynamicLinker = getString(Args, OPT_dynamic_linker);
   Config->Entry = getString(Args, OPT_entry);
   Config->Fini = getString(Args, OPT_fini, "_fini");
   Config->Init = getString(Args, OPT_init, "_init");
+  Config->LtoAAPipeline = getString(Args, OPT_lto_aa_pipeline);
   Config->LtoNewPmPasses = getString(Args, OPT_lto_newpm_passes);
   Config->OutputFile = getString(Args, OPT_o);
   Config->SoName = getString(Args, OPT_soname);
   Config->Sysroot = getString(Args, OPT_sysroot);
 
   Config->Optimize = getInteger(Args, OPT_O, 1);
   Config->LtoO = getInteger(Args, OPT_lto_O, 2);
   if (Config->LtoO > 3)

lld/trunk/ELF/LTO.cpp

static void saveBCFile(Module &M, StringRef Suffix) {
   check(EC);
   WriteBitcodeToFile(&M, OS, /* ShouldPreserveUseListOrder */ true);
 }
 
 static void runNewCustomLtoPasses(Module &M, TargetMachine &TM) {
   PassBuilder PB(&TM);
 
   AAManager AA;
+
+  // Parse a custom AA pipeline if asked to.
+  if (!PB.parseAAPipeline(AA, Config->LtoAAPipeline)) {
+    error("Unable to parse AA pipeline description: " + Config->LtoAAPipeline);
+    return;
+  }
+
   LoopAnalysisManager LAM;
   FunctionAnalysisManager FAM;
   CGSCCAnalysisManager CGAM;
   ModuleAnalysisManager MAM;
 
   // Register the AA manager first so that our version is the one used.
   FAM.registerPass([&] { return std::move(AA); });
 

lld/trunk/ELF/Options.td

 def alias_define_common_d : Flag<["-"], "d">, Alias<define_common>;
 def alias_define_common_dc : Flag<["-"], "dc">, Alias<define_common>;
 def alias_define_common_dp : Flag<["-"], "dp">, Alias<define_common>;
 def alias_version_script_version_script : Joined<["--"], "version-script=">, Alias<version_script>;
 
 // LTO-related options.
 def lto_jobs : Joined<["--"], "lto-jobs=">,
   HelpText<"Number of threads to run codegen">;
+def lto_aa_pipeline : Joined<["--"], "lto-aa-pipeline=">,
+  HelpText<"AA pipeline to run during LTO. Used in conjunction with -lto-newpm-passes">;
 def lto_newpm_passes : Joined<["--"], "lto-newpm-passes=">,
   HelpText<"Passes to run during LTO">;
 def disable_verify : Flag<["-"], "disable-verify">;
 def mllvm : Separate<["-"], "mllvm">;
 def save_temps : Flag<["-"], "save-temps">;

lld/trunk/test/ELF/lto/ltopasses-custom.ll

 ; REQUIRES: x86
 ; RUN: llvm-as %s -o %t.o
-; RUN: ld.lld -m elf_x86_64 %t.o -o %t.so -save-temps --lto-newpm-passes=ipsccp -shared
+; RUN: ld.lld -m elf_x86_64 %t.o -o %t.so -save-temps --lto-aa-pipeline=basic-aa \
+; RUN: --lto-newpm-passes=ipsccp -shared
 ; RUN: ld.lld -m elf_x86_64 %t.o -o %t2.so -save-temps --lto-newpm-passes=loweratomic -shared
 ; RUN: llvm-dis %t.so.lto.opt.bc -o - | FileCheck %s
 ; RUN: llvm-dis %t2.so.lto.opt.bc -o - | FileCheck %s --check-prefix=ATOMIC
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
 define void @barrier() {