Use named temporaries for directional labels.

Directional labels can show up in symbol tables (and we have a llvm-mc test for
that). Given that, we need to make sure they are named.

With that out of the way, use setUseNamesOnTempLabels in llvm-mc so that it
too benefits from the memory saving.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239914 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/MC/MCContext.h

@@ -207,7 +207,7 @@ namespace llvm {
     bool AutoReset;
 
     MCSymbol *createSymbolImpl(const StringMapEntry<bool> *Name,
-                               bool IsTemporary);
+                               bool CanBeUnnamed);
     MCSymbol *createSymbol(StringRef Name, bool AlwaysAddSuffix,
                            bool IsTemporary);
 
@@ -249,9 +249,10 @@ namespace llvm {
 
     /// Create and return a new assembler temporary symbol with a unique but
     /// unspecified name.
-    MCSymbol *createTempSymbol();
+    MCSymbol *createTempSymbol(bool CanBeUnnamed = true);
 
-    MCSymbol *createTempSymbol(const Twine &Name, bool AlwaysAddSuffix);
+    MCSymbol *createTempSymbol(const Twine &Name, bool AlwaysAddSuffix,
+                               bool CanBeUnnamed = true);
 
     /// Create the definition of a directional local symbol for numbered label
     /// (used for "1:" definitions).