[LTO] Call InitLLVM from llvm-lto2

[tejohnson]

Summary

D45602 added this to most tools, including llvm-lto, but not to
llvm-lto2. Add it there and test that it works in both lto tools.

[ruiu]

LGTM

test/ThinLTO/X86/deadstrip.ll

 ; Require asserts for -debug-only
 ; REQUIRES: asserts
 
 ; RUN: opt -module-summary %s -o %t1.bc
 ; RUN: opt -module-summary %p/Inputs/deadstrip.ll -o %t2.bc
 ; RUN: llvm-lto -thinlto-action=thinlink -o %t.index.bc %t1.bc %t2.bc
 
 ; RUN: llvm-lto -exported-symbol=_main -thinlto-action=promote %t1.bc -thinlto-index=%t.index.bc -o - | llvm-lto -exported-symbol=_main -thinlto-action=internalize -thinlto-index %t.index.bc -thinlto-module-id=%t1.bc - -o - | llvm-dis -o - | FileCheck %s
 ; RUN: llvm-lto -exported-symbol=_main -thinlto-action=promote %t2.bc -thinlto-index=%t.index.bc -o - | llvm-lto -exported-symbol=_main -thinlto-action=internalize -thinlto-index %t.index.bc -thinlto-module-id=%t2.bc - -o - | llvm-dis -o - | FileCheck %s --check-prefix=CHECK2
 
-; RUN: llvm-lto -exported-symbol=_main -thinlto-action=run %t1.bc %t2.bc
+; RUN: llvm-lto -exported-symbol=_main -thinlto-action=run -stats %t1.bc %t2.bc 2>&1 | FileCheck %s --check-prefix=STATS
 ; RUN: llvm-nm %t1.bc.thinlto.o | FileCheck %s --check-prefix=CHECK-NM
 
-; RUN: llvm-lto2 run %t1.bc %t2.bc -o %t.out -save-temps \
+; RUN: llvm-lto2 run %t1.bc %t2.bc -o %t.out -save-temps -stats \
 ; RUN:   -r %t1.bc,_main,plx \
 ; RUN:   -r %t1.bc,_bar,pl \
 ; RUN:   -r %t1.bc,_dead_func,pl \
 ; RUN:   -r %t1.bc,_baz,l \
 ; RUN:   -r %t1.bc,_boo,l \
 ; RUN:   -r %t1.bc,_live_available_externally_func,l \
 ; RUN:   -r %t1.bc,_live_linkonce_odr_func,l \
 ; RUN:   -r %t1.bc,_live_weak_odr_func,l \
 ; RUN:   -r %t2.bc,_baz,pl \
 ; RUN:   -r %t2.bc,_boo,pl \
 ; RUN:   -r %t2.bc,_dead_func,l \
 ; RUN:   -r %t2.bc,_another_dead_func,pl \
 ; RUN:   -thinlto-threads=1 \
-; RUN:   -debug-only=function-import 2>&1 | FileCheck %s --check-prefix=DEBUG
+; RUN:   -debug-only=function-import 2>&1 | FileCheck %s --check-prefix=DEBUG --check-prefix=STATS
 ; RUN: llvm-dis < %t.out.1.3.import.bc | FileCheck %s --check-prefix=LTO2
 ; RUN: llvm-dis < %t.out.2.3.import.bc | FileCheck %s --check-prefix=LTO2-CHECK2
 ; RUN: llvm-nm %t.out.1 | FileCheck %s --check-prefix=CHECK2-NM
 
 ; RUN: llvm-bcanalyzer -dump %t.out.index.bc | FileCheck %s --check-prefix=COMBINED
 ; Live, NotEligibleForImport, dso_local, Internal
 ; COMBINED-DAG: <COMBINED {{.*}} op2=119
 ; Live, dso_local, Internal

 
 ; DEBUG-DAG: Live root: 2412314959268824392 (llvm.global_ctors)
 ; DEBUG-DAG: Live root: 15822663052811949562 (main)
 ; DEBUG-DAG: Ignores Dead GUID: 7342339837106705152 (dead_func)
 ; DEBUG-DAG: Ignores Dead GUID: 7546896869197086323 (baz)
 ; DEBUG-DAG: Initialize import for 15611644523426561710 (boo)
 ; DEBUG-DAG: Ignores Dead GUID: 2384416018110111308 (another_dead_func)
 
+; STATS: 3 function-import  - Number of dead stripped symbols in index
+
 ; Next test the case where Inputs/deadstrip.ll does not get a module index,
 ; which will cause it to be handled by regular LTO in the new LTO API.
 ; In that case there are uses of @dead_func in the regular LTO partition
 ; and it shouldn't be internalized.
 ; RUN: opt %p/Inputs/deadstrip.ll -o %t3.bc
 ; RUN: llvm-lto2 run %t1.bc %t3.bc -o %t4.out -save-temps \
 ; RUN:   -r %t1.bc,_main,plx \
 ; RUN:   -r %t1.bc,_bar,pl \

tools/llvm-lto2/llvm-lto2.cpp

 
 #include "llvm/Bitcode/BitcodeReader.h"
 #include "llvm/CodeGen/CommandFlags.inc"
 #include "llvm/IR/DiagnosticPrinter.h"
 #include "llvm/LTO/Caching.h"
 #include "llvm/LTO/LTO.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/FileSystem.h"
+#include "llvm/Support/InitLLVM.h"
 #include "llvm/Support/TargetSelect.h"
 #include "llvm/Support/Threading.h"
 
 using namespace llvm;
 using namespace lto;
 
 static cl::opt<char>
     OptLevel("O", cl::desc("Optimization level. [-O0, -O1, -O2, or -O3] "
for (StringRef F : make_range(argv + 1, argv + argc)) {
 
     outs() << '\n';
   }
 
   return 0;
 }
 
 int main(int argc, char **argv) {
+  InitLLVM X(argc, argv);
   InitializeAllTargets();
   InitializeAllTargetMCs();
   InitializeAllAsmPrinters();
   InitializeAllAsmParsers();
 
   // FIXME: This should use llvm::cl subcommands, but it isn't currently
   // possible to pass an argument not associated with a subcommand to a
   // subcommand (e.g. -use-new-pm).