Adding a collector name attribute to Function in the IR. These

methods are new to Function:

  bool hasCollector() const;
  const std::string &getCollector() const;
  void setCollector(const std::string &);
  void clearCollector();

The assembly representation is as such:

  define void @f() gc "shadow-stack" { ...

The implementation uses an on-the-side table to map Functions to 
collector names, such that there is no overhead. A StringPool is 
further used to unique collector names, which are extremely
likely to be unique per process.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@44769 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Bitcode/LLVMBitCodes.h

@@ -58,7 +58,9 @@ namespace bitc {
     MODULE_CODE_ALIAS       = 9,
     
     /// MODULE_CODE_PURGEVALS: [numvals]
-    MODULE_CODE_PURGEVALS   = 10
+    MODULE_CODE_PURGEVALS   = 10,
+    
+    MODULE_CODE_COLLECTORNAME = 11   // COLLECTORNAME: [strchr x N]
   };
   
   /// PARAMATTR blocks have code for defining a parameter attribute set.