[lld-macho] Make `--icf=safe` work with LTO

[int3]

Summary

Just matter of enabling the config option.

(Also changed the platform of the input test file to macOS, since that's
the default that we specify in the %lld substitution. The conflict was
causing errors when linking with LTO.)

[int3]

lld/test/MachO/icf-safe.ll

5

question for @alexbdv: why the use of -O3 and -enable-machine-outliner=never here?

lld/MachO/LTO.cpp

 using namespace lld::macho;
 using namespace llvm;
 using namespace llvm::MachO;
 using namespace llvm::sys;
 
 static lto::Config createConfig() {
   lto::Config c;
   c.Options = initTargetOptionsFromCodeGenFlags();
+  c.Options.EmitAddrsig = config->icfLevel == ICFLevel::safe;
   c.CodeModel = getCodeModelFromCMModel();
   c.CPU = getCPUStr();
   c.MAttrs = getMAttrs();
   c.DiagHandler = diagnosticHandler;
   c.PreCodeGenPassesHook = [](legacy::PassManager &pm) {
     pm.add(createObjCARCContractPass());
   };
   c.TimeTraceEnabled = config->timeTraceEnabled;

lld/test/MachO/icf-safe.ll

+; REQUIRES: aarch64
+
 ; RUN: rm -rf %t; mkdir %t
-; RUN: llc -filetype=obj %s -O3 -o %t/icf-obj.o -enable-machine-outliner=never -mtriple arm64-apple-ios -addrsig
+
+; RUN: llc -filetype=obj %s -O3 -o %t/icf-obj.o -enable-machine-outliner=never -mtriple arm64-apple-macos -addrsig
 ; RUN: %lld -arch arm64 -lSystem --icf=safe -dylib -o %t/icf-safe.dylib %t/icf-obj.o
 ; RUN: %lld -arch arm64 -lSystem --icf=all  -dylib -o %t/icf-all.dylib  %t/icf-obj.o
 ; RUN: llvm-objdump %t/icf-safe.dylib -d --macho | FileCheck %s --check-prefix=ICFSAFE
 ; RUN: llvm-objdump %t/icf-all.dylib  -d --macho | FileCheck %s --check-prefix=ICFALL
 
+; RUN: llvm-as %s -o %t/icf-bitcode.o
+; RUN: %lld -arch arm64 -lSystem --icf=safe -dylib -o %t/icf-safe-bitcode.dylib %t/icf-bitcode.o
+; RUN: %lld -arch arm64 -lSystem --icf=all  -dylib -o %t/icf-all-bitcode.dylib %t/icf-bitcode.o
+; RUN: llvm-objdump %t/icf-safe-bitcode.dylib -d --macho | FileCheck %s --check-prefix=ICFSAFE
+; RUN: llvm-objdump %t/icf-all-bitcode.dylib  -d --macho | FileCheck %s --check-prefix=ICFALL
+
 ; ICFSAFE-LABEL:  _callAllFunctions
 ; ICFSAFE:        bl _func02
 ; ICFSAFE-NEXT:   bl _func02
 ; ICFSAFE-NEXT:   bl _func03_takeaddr
 
 ; ICFALL-LABEL:   _callAllFunctions
 ; ICFALL:         bl _func03_takeaddr
 ; ICFALL-NEXT:    bl _func03_takeaddr
 ; ICFALL-NEXT:    bl _func03_takeaddr
 
-; REQUIRES: aarch64
-
 target datalayout = "e-m:o-i64:64-i128:128-n32:64-S128"
-target triple = "arm64-apple-ios7.0.0"
+target triple = "arm64-apple-macos11.0"
 
 @result = global i32 0, align 4
 
 define void @func01() local_unnamed_addr noinline {
 entry:
   %0 = load volatile i32, ptr @result, align 4
   %add = add nsw i32 %0, 1
   store volatile i32 %add, ptr @result, align 4