Instructions: add missing anchors. NFC

[thegameg]

Summary

FCmpInst, ExtractValueInst and InsertValueInst have no anchor functions. This
causes the vtable and the type info (if RTTI is enabled in user code) to
be emitted in multiple translation units (and the Coding Standards
enforce the presence of an anchor method).

The problem has occured here:
http://lists.llvm.org/pipermail/llvm-dev/2016-February/095654.html

[thegameg]

Thanks for the review. I don't have commit rights, can you commit this for me?

[thegameg]

@jlebar: Would you mind committing this for me, please?

[Eugene.Zelenko]

Looks like patch was not committed.

[rnk]

IMO rather than anchoring the vtables we should remove them completely. The only virtual method left is the destructor, and we can switch-ify that.

include/llvm/IR/Instructions.h

 /// vectors of floating point values. The operands must be identical types.
 /// \brief Represents a floating point comparison operator.
 class FCmpInst: public CmpInst {
+  void anchor() override;
+
 protected:
   // Note: Instruction needs to be a friend here to call cloneImpl.
   friend class Instruction;

 class ExtractValueInst : public UnaryInstruction {
   SmallVector<unsigned, 4> Indices;
 
+  void anchor() override;
+
   ExtractValueInst(const ExtractValueInst &EVI);
   void init(ArrayRef<unsigned> Idxs, const Twine &NameStr);
 

 class InsertValueInst : public Instruction {
   SmallVector<unsigned, 4> Indices;
 
+  void anchor() override;
+
   void *operator new(size_t, unsigned) = delete;
   InsertValueInst(const InsertValueInst &IVI);
   void init(Value *Agg, Value *Val, ArrayRef<unsigned> Idxs,

lib/IR/Instructions.cpp

 //                             InsertValueInst Class
 //===----------------------------------------------------------------------===//
 
+void InsertValueInst::anchor() {}
+
 void InsertValueInst::init(Value *Agg, Value *Val, ArrayRef<unsigned> Idxs, 
                            const Twine &Name) {
   assert(getNumOperands() == 2 && "NumOperands not initialized?");

 //                             ExtractValueInst Class
 //===----------------------------------------------------------------------===//
 
+void ExtractValueInst::anchor() {}
+
 void ExtractValueInst::init(ArrayRef<unsigned> Idxs, const Twine &Name) {
   assert(getNumOperands() == 1 && "NumOperands not initialized?");
 

   }
 }
 
+void FCmpInst::anchor() {}
+
 
 //===----------------------------------------------------------------------===//
 //                        SwitchInst Implementation