[IR] Add operand bundles to CallInst and InvokeInst.

Summary:
This change teaches `CallInst`s and `InvokeInst`s to maintain a set of
operand bundles as part of its operands.  `CallInst`s and `InvokeInst`s
with operand bundles co-allocate some space before their `Use` array to
hold meta information about which of its operands are part of an operand
bundle.

The strings corresponding to the bundle tags are interned into
`LLVMContextImpl::BundleTagCache`

This change does not include any parsing / bitcode support.  That's the
next change.

Depends on D12455.

Reviewers: reames, chandlerc, majnemer, dexonsmith, kmod, JosephTremoulet, rnk, bogner

Subscribers: MatzeB, sanjoy, llvm-commits

Differential Revision: http://reviews.llvm.org/D12456

llvm-svn: 248527
diff --git a/llvm/lib/IR/LLVMContextImpl.h b/llvm/lib/IR/LLVMContextImpl.h
index cf0aa5c..1d41069 100644
--- a/llvm/lib/IR/LLVMContextImpl.h
+++ b/llvm/lib/IR/LLVMContextImpl.h
@@ -986,6 +986,16 @@
   int getOrAddScopeRecordIdxEntry(MDNode *N, int ExistingIdx);
   int getOrAddScopeInlinedAtIdxEntry(MDNode *Scope, MDNode *IA,int ExistingIdx);
 
+  /// \brief A set of interned tags for operand bundles.  The StringMap maps
+  /// bundle tags to their IDs.
+  ///
+  /// \see LLVMContext::getOperandBundleTagID
+  StringMap<uint32_t> BundleTagCache;
+
+  StringMapEntry<uint32_t> *getOrInsertBundleTag(StringRef Tag);
+  void getOperandBundleTags(SmallVectorImpl<StringRef> &Tags) const;
+  uint32_t getOperandBundleTagID(StringRef Tag) const;
+
   LLVMContextImpl(LLVMContext &C);
   ~LLVMContextImpl();