Address reviewer feedback.

Fix --line-numbers with --macho and add test.
Use std::optional to defer initialization of SourcePrinter/LiveElementPrinter.

Author: rjmansfield

llvm/test/tools/llvm-objdump/MachO/disassemble-source-dsym.test

@@ -13,7 +13,7 @@
 # RUN: dsymutil -f  -oso-prepend-path=%p/../../dsymutil/ %t3 -o %t3.dSYM
 # RUN: llvm-objdump --source --prefix=%p/../../dsymutil  %t3 | FileCheck --check-prefix=SOURCE %s
 
-## Test that --source works with --macho flag
+## Test that --source works with --macho flag.
 
 ## --macho w/ explicit .dSYM
 # RUN: llvm-objdump < %p/../../dsymutil/Inputs/basic.macho.x86_64 - --source --macho --dsym=%t1.dSYM --prefix=%p/../../dsymutil | \
@@ -26,3 +26,22 @@
 # RUN: llvm-objdump --source --macho --prefix=%p/../../dsymutil %t3 | FileCheck --check-prefix=SOURCE %s
 
 # SOURCE: ; int bar(int arg) {
+
+## Test that --line-numbers works with --macho flag.
+
+## --macho -l w/ explicit .dSYM
+# RUN: llvm-objdump -d -l --macho --dsym=%t1.dSYM %p/../../dsymutil/Inputs/basic.macho.x86_64 | FileCheck --check-prefix=LINE %s
+
+## --macho -l w/ object file (embedded debug info)
+# RUN: llvm-objdump -d -l --macho %p/../../dsymutil/Inputs/basic1.macho.x86_64.o | FileCheck --check-prefix=LINE_OBJ %s
+
+# LINE: (__TEXT,__text) section
+# LINE: _bar:
+# LINE: ; bar():
+# LINE: ; {{.*}}basic3.c:
+
+# LINE_OBJ: (__TEXT,__text) section
+# LINE_OBJ: _main:
+# LINE_OBJ: ; main():
+# LINE_OBJ: ; {{.*}}basic1.c:23
+# LINE_OBJ: pushq %rbp ## basic1.c:23:0

llvm/tools/llvm-objdump/MachODump.cpp

@@ -7425,14 +7425,18 @@ static void DisassembleMachO(StringRef Filename, MachOObjectFile *MachOOF,
     if (!DSym)
       return;
     DbgObj = DSym;
-    if (UseDbg) {
+    if (UseDbg || PrintLines) {
       // Setup the DIContext
       diContext = DWARFContext::create(*DbgObj);
     }
   }
 
-  SourcePrinter SP(DbgObj, TheTarget->getName());
-  LiveElementPrinter LEP(*MRI, *STI);
+  std::optional<SourcePrinter> SP;
+  std::optional<LiveElementPrinter> LEP;
+  if (PrintSource || PrintLines) {
+    SP.emplace(DbgObj, TheTarget->getName());
+    LEP.emplace(*MRI, *STI);
+  }
 
   if (FilterSections.empty())
     outs() << "(" << DisSegName << "," << DisSectName << ") section\n";
@@ -7615,7 +7619,7 @@ static void DisassembleMachO(StringRef Filename, MachOObjectFile *MachOOF,
 
         if (PrintSource || PrintLines) {
           formatted_raw_ostream FOS(outs());
-          SP.printSourceLine(FOS, {PC, SectIdx}, Filename, LEP);
+          SP->printSourceLine(FOS, {PC, SectIdx}, Filename, *LEP);
         }
 
         if (LeadingAddr) {
@@ -7711,7 +7715,7 @@ static void DisassembleMachO(StringRef Filename, MachOObjectFile *MachOOF,
 
         if (PrintSource || PrintLines) {
           formatted_raw_ostream FOS(outs());
-          SP.printSourceLine(FOS, {PC, SectIdx}, Filename, LEP);
+          SP->printSourceLine(FOS, {PC, SectIdx}, Filename, *LEP);
         }
 
         if (DumpAndSkipDataInCode(PC, Bytes.data() + Index, Dices, InstSize))