[LTO] Add support for existing Config::Freestanding option.

[fhahn]

Summary

lto::Config has a field to control whether the build is "freestanding"
(no builtins) or not, but it is not hooked up to the code actually
running the passes.

This patch adds support for the flag to both the code that runs
optimization with the new and old pass managers, by explicitly adding a
TargetLibraryInfo instance. If Freestanding is true, all library functions
are disabled.

[fhahn]

llvm/lib/LTO/LTOBackend.cpp

313

@asbirlea I am trying to make the new PM use a TargetLibraryInfo with all functions disabled here. But for some reason, it appears as if the custom TLI is not used. Do you have any idea what the right way to do that would be?

[fhahn]

ping

[steven_wu]

LGTM. Did you figure out the answer of your inline comment?

[fhahn]

In D94630#2512841, @steven_wu wrote:

LGTM. Did you figure out the answer of your inline comment?

Unfortunately not so far. @aeubanks @asbirlea do you know how to best disable all builtin functions with new NewPM?

[aeubanks]

llvm/lib/LTO/LTOBackend.cpp

313

I think you want runNewPMPasses on top of runNewPMCustomPasses (idk how much runNewPMCustomPasses is used).

[asbirlea]

llvm/lib/LTO/LTOBackend.cpp

313

^ add these changes to runNewPMPasses as well.

[fhahn]

handle freestanding also for runNewPMPasses, add test for runNewPMCustomPasses.

This works as expected with the NewPM now, thanks!

llvm/lib/LTO/LTOBackend.cpp

313

Ah, there are 2 helpers for the NewPM, thanks!

[steven_wu]

Looks good now. Thanks.

llvm/lib/LTO/LTOBackend.cpp

static void runNewPMPasses(const Config &Conf, Module &Mod, TargetMachine *TM,
 
   RegisterPassPlugins(Conf.PassPlugins, PB);
 
   LoopAnalysisManager LAM(Conf.DebugPassManager);
   FunctionAnalysisManager FAM(Conf.DebugPassManager);
   CGSCCAnalysisManager CGAM(Conf.DebugPassManager);
   ModuleAnalysisManager MAM(Conf.DebugPassManager);
 
+  std::unique_ptr<TargetLibraryInfoImpl> TLII(
+      new TargetLibraryInfoImpl(Triple(TM->getTargetTriple())));
+  if (Conf.Freestanding)
+    TLII->disableAllFunctions();
+  FAM.registerPass([&] { return TargetLibraryAnalysis(*TLII); });
+
   // Register the AA manager first so that our version is the one used.
   FAM.registerPass([&] { return std::move(AA); });
 
   // Register all the basic analyses with the managers.
   PB.registerModuleAnalyses(MAM);
   PB.registerCGSCCAnalyses(CGAM);
   PB.registerFunctionAnalyses(FAM);
   PB.registerLoopAnalyses(LAM);
static void runNewPMCustomPasses(const Config &Conf, Module &Mod,
 
   RegisterPassPlugins(Conf.PassPlugins, PB);
 
   LoopAnalysisManager LAM;
   FunctionAnalysisManager FAM;
   CGSCCAnalysisManager CGAM;
   ModuleAnalysisManager MAM;
 
+  std::unique_ptr<TargetLibraryInfoImpl> TLII(
+      new TargetLibraryInfoImpl(Triple(TM->getTargetTriple())));
+  if (Conf.Freestanding)
+    TLII->disableAllFunctions();
+  FAM.registerPass([&] { return TargetLibraryAnalysis(*TLII); });
+
   // Register the AA manager first so that our version is the one used.
   FAM.registerPass([&] { return std::move(AA); });
 
   // Register all the basic analyses with the managers.
   PB.registerModuleAnalyses(MAM);
   PB.registerCGSCCAnalyses(CGAM);
   PB.registerFunctionAnalyses(FAM);
   PB.registerLoopAnalyses(LAM);

 static void runOldPMPasses(const Config &Conf, Module &Mod, TargetMachine *TM,
                            bool IsThinLTO, ModuleSummaryIndex *ExportSummary,
                            const ModuleSummaryIndex *ImportSummary) {
   legacy::PassManager passes;
   passes.add(createTargetTransformInfoWrapperPass(TM->getTargetIRAnalysis()));
 
   PassManagerBuilder PMB;
   PMB.LibraryInfo = new TargetLibraryInfoImpl(Triple(TM->getTargetTriple()));
+  if (Conf.Freestanding)
+    PMB.LibraryInfo->disableAllFunctions();
   PMB.Inliner = createFunctionInliningPass();
   PMB.ExportSummary = ExportSummary;
   PMB.ImportSummary = ImportSummary;
   // Unconditionally verify input since it is not verified before this
   // point and has unknown origin.
   PMB.VerifyInput = true;
   PMB.VerifyOutput = !Conf.DisableVerify;
   PMB.LoopVectorize = true;

llvm/test/LTO/X86/tli-nobuiltin.ll

 ; Test -lto-freestanding option for libLTO.
 ; RUN: llvm-as < %s > %t.bc
 
 ; Regular run: expects fprintf to be turned into fwrite
 ; RUN: llvm-lto %t.bc -exported-symbol=_foo -o %t.o
 ; RUN: llvm-nm %t.o | FileCheck %s --check-prefix=LTO
 ; LTO: fwrite
 
 ; Freestanding run: expects fprintf to NOT be turned into fwrite
 ; RUN: llvm-lto %t.bc -lto-freestanding -exported-symbol=_foo -o %t.o
 ; RUN: llvm-nm %t.o | FileCheck %s --check-prefix=LTO-FREESTANDING
 ; LTO-FREESTANDING: fprintf
 
+; Test -lto-freestanding option for LTOBackend & legacy PM.
+
+; RUN: llvm-lto2 run -r %t.bc,_fprintf,px -r %t.bc,_hello_world,px -r %t.bc,_percent_s,px  -r %t.bc,_foo,px %t.bc -o %t1.o 2>&1
+; RUN: llvm-nm %t1.o.0 | FileCheck %s --check-prefix=LTO
+
+; RUN: llvm-lto2 run -lto-freestanding -r %t.bc,_fprintf,px -r %t.bc,_hello_world,px -r %t.bc,_percent_s,px  -r %t.bc,_foo,px %t.bc -o %t2.o 2>&1
+; RUN: llvm-nm %t2.o.0 | FileCheck %s --check-prefix=LTO-FREESTANDING
+
+; Test -lto-freestanding option for LTOBackend & new PM.
+
+; RUN: llvm-lto2 run -use-new-pm -r %t.bc,_fprintf,px -r %t.bc,_hello_world,px -r %t.bc,_percent_s,px  -r %t.bc,_foo,px %t.bc -o %t1.o 2>&1
+; RUN: llvm-nm %t1.o.0 | FileCheck %s --check-prefix=LTO
+
+; RUN: llvm-lto2 run -use-new-pm -lto-freestanding -r %t.bc,_fprintf,px -r %t.bc,_hello_world,px -r %t.bc,_percent_s,px  -r %t.bc,_foo,px %t.bc -o %t2.o 2>&1
+; RUN: llvm-nm %t2.o.0 | FileCheck %s --check-prefix=LTO-FREESTANDING
+
+; Test -lto-freestanding option for LTOBackend & new PM with custom pipeline.
+
+; RUN: llvm-lto2 run -use-new-pm -opt-pipeline='default<O3>' -r %t.bc,_fprintf,px -r %t.bc,_hello_world,px -r %t.bc,_percent_s,px  -r %t.bc,_foo,px %t.bc -o %t1.o 2>&1
+; RUN: llvm-nm %t1.o.0 | FileCheck %s --check-prefix=LTO
+
+; RUN: llvm-lto2 run -use-new-pm -opt-pipeline='default<O3>' -lto-freestanding -r %t.bc,_fprintf,px -r %t.bc,_hello_world,px -r %t.bc,_percent_s,px  -r %t.bc,_foo,px %t.bc -o %t2.o 2>&1
+; RUN: llvm-nm %t2.o.0 | FileCheck %s --check-prefix=LTO-FREESTANDING
+
+
 target datalayout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-apple-macosx10.11.0"
 
 declare i32 @fprintf(%FILE*, i8*, ...)
 
 %FILE = type { }
 
 @hello_world = constant [13 x i8] c"hello world\0A\00"

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

 
 static cl::opt<std::string>
     StatsFile("stats-file", cl::desc("Filename to write statistics to"));
 
 static cl::list<std::string>
     PassPlugins("load-pass-plugin",
                 cl::desc("Load passes from plugin library"));
 
+static cl::opt<bool> EnableFreestanding(
+    "lto-freestanding",
+    cl::desc("Enable Freestanding (disable builtins / TLI) during LTO"),
+    cl::init(false), cl::Hidden);
+
 static void check(Error E, std::string Msg) {
   if (!E)
     return;
   handleAllErrors(std::move(E), [&](ErrorInfoBase &EIB) {
     errs() << "llvm-lto2: " << Msg << ": " << EIB.message().c_str() << '\n';
   });
   exit(1);
 }
static int run(int argc, char **argv) {
   Conf.RunCSIRInstr = RunCSIRInstr;
 
   // Run a custom pipeline, if asked for.
   Conf.OptPipeline = OptPipeline;
   Conf.AAPipeline = AAPipeline;
 
   Conf.OptLevel = OptLevel - '0';
   Conf.UseNewPM = UseNewPM;
+  Conf.Freestanding = EnableFreestanding;
   for (auto &PluginFN : PassPlugins)
     Conf.PassPlugins.push_back(PluginFN);
   switch (CGOptLevel) {
   case '0':
     Conf.CGOptLevel = CodeGenOpt::None;
     break;
   case '1':
     Conf.CGOptLevel = CodeGenOpt::Less;