MC: Make save-temp-labels imply UseNamesOnTempLabels

UseNamesOnTempLabels was false in MCObjectStreamer. `createTempSymbol`
created symbols were unnamed, making debugging difficult.

Author: MaskRay

llvm/lib/MC/MCContext.cpp

@@ -75,6 +75,8 @@ MCContext::MCContext(const Triple &TheTriple, const MCAsmInfo *mai,
       CurrentDwarfLoc(0, 0, 0, DWARF2_FLAG_IS_STMT, 0, 0),
       AutoReset(DoAutoReset), TargetOptions(TargetOpts) {
   SaveTempLabels = TargetOptions && TargetOptions->MCSaveTempLabels;
+  if (SaveTempLabels)
+    setUseNamesOnTempLabels(true);
   SecureLogFile = TargetOptions ? TargetOptions->AsSecureLogFile : "";
 
   if (SrcMgr && SrcMgr->getNumBuffers())

llvm/test/MC/ELF/mc-dump.s

@@ -27,6 +27,17 @@
 # CHECK-NEXT:5 LEB Value:.Ltmp0-_start Signed:0
 # CHECK-NEXT:]
 
+# RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o %t -debug-only=mc-dump -save-temp-labels -g 2>&1 | FileCheck %s --check-prefix=CHECK2
+
+#      CHECK2:5 Data Size:16 [48,8b,04,25,00,00,00,00,48,8b,04,25,00,00,00,00]
+# CHECK2-NEXT:  Fixup @4 Value:f0@<variant 11> Kind:4021
+# CHECK2-NEXT:  Fixup @12 Value:_start@<variant 11> Kind:4021
+# CHECK2-NEXT:  Symbol @16 .Ltmp1
+# CHECK2-NEXT:  Symbol @0 .Ltmp3 Temporary
+# CHECK2-NEXT:  Symbol @8 .Ltmp4 Temporary
+# CHECK2-NEXT:  Symbol @16 .Ltmp5 Temporary
+# CHECK2-NEXT:  Symbol @16 .Lsec_end0 Temporary
+
 _start:
 var = _start
 .org 3