Allow symbols to start from the digit if target requests it. This allows, e.g. pinning

variables to specified absolute address. Make use of this feature for MSP430.
This unbreaks PR4776.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82227 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Support/Mangler.h

@@ -51,6 +51,10 @@ private:
   /// the space character.  By default, this is false.
   bool UseQuotes;
 
+  /// SymbolsCanStartWithDigit - If this is set, the target allows symbols to
+  /// start with digits (e.g., "0x0021").  By default, this is false.
+  bool SymbolsCanStartWithDigit;
+
   /// AnonGlobalIDs - We need to give global values the same name every time
   /// they are mangled.  This keeps track of the number we give to anonymous
   /// ones.
@@ -75,9 +79,13 @@ public:
   /// strings for assembler labels.
   void setUseQuotes(bool Val) { UseQuotes = Val; }
 
+  /// setSymbolsCanStartWithDigit - If SymbolsCanStartWithDigit is set to true,
+  /// this target allows symbols to start with digits.
+  void setSymbolsCanStartWithDigit(bool Val) { SymbolsCanStartWithDigit = Val; }
+
   /// Acceptable Characters - This allows the target to specify which characters
   /// are acceptable to the assembler without being mangled.  By default we
-  /// allow letters, numbers, '_', '$', and '.', which is what GAS accepts.
+  /// allow letters, numbers, '_', '$', '.', which is what GAS accepts, and '@'.
   void markCharAcceptable(unsigned char X) {
     AcceptableChars[X/32] |= 1 << (X&31);
   }