Small improvements to Intrinsic::getName

[lxfind]

Summary

While I was adding a new intrinsic instruction (not overloaded), I accidentally used CreateUnaryIntrinsic to create the intrinsics, which turns out to be passing the type list to getName, and ended up naming the intrinsics function with type suffix, which leads to wierd bugs latter on. It took me a long time to debug.
It seems a good idea to add an assertion in getName so that it fails if types are passed but it's not a overloaded function.
Also, the overloade version of getName is less efficient because it creates an std::string. We should avoid calling it if we know that there are no types provided.

[pete]

LGTM. Thanks for doing this!

[erichkeane]

I note here: https://llvm.org/doxygen/namespacellvm_1_1Intrinsic.html#a7157f9fa9dd11f234ec3c58517cb6d96 that the documentatoin to the getName function variant says:

"If no overloads are requried, it is safe to use this version, but better to use the StringRef version."

It seems that this assert isn't consistent with the documentation on the function. I believe one of the two needs to be fixed.

Actually... I see you actually get that right... and my case (having something not officially 'overloaded', but needing the overloaded name) isn't covered by the docs. Sorry 'bout that.

llvm/lib/IR/Function.cpp

StringRef Intrinsic::getName(ID id) {
   assert(id < num_intrinsics && "Invalid intrinsic ID!");
   assert(!Intrinsic::isOverloaded(id) &&
          "This version of getName does not support overloading");
   return IntrinsicNameTable[id];
 }
 
 std::string Intrinsic::getName(ID id, ArrayRef<Type*> Tys) {
   assert(id < num_intrinsics && "Invalid intrinsic ID!");
+  assert((Tys.empty() || Intrinsic::isOverloaded(id)) &&
+         "This version of getName is for overloaded intrinsics only");
   std::string Result(IntrinsicNameTable[id]);
   for (Type *Ty : Tys) {
     Result += "." + getMangledTypeStr(Ty);
   }
   return Result;
 }
 
 /// IIT_Info - These are enumerators that describe the entries returned by the

 #define GET_INTRINSIC_ATTRIBUTES
 #include "llvm/IR/IntrinsicImpl.inc"
 #undef GET_INTRINSIC_ATTRIBUTES
 
 Function *Intrinsic::getDeclaration(Module *M, ID id, ArrayRef<Type*> Tys) {
   // There can never be multiple globals with the same name of different types,
   // because intrinsics must be a specific type.
   return cast<Function>(
-      M->getOrInsertFunction(getName(id, Tys),
+      M->getOrInsertFunction(Tys.empty() ? getName(id) : getName(id, Tys),
                              getType(M->getContext(), id, Tys))
           .getCallee());
 }
 
 // This defines the "Intrinsic::getIntrinsicForGCCBuiltin()" method.
 #define GET_LLVM_INTRINSIC_FOR_GCC_BUILTIN
 #include "llvm/IR/IntrinsicImpl.inc"
 #undef GET_LLVM_INTRINSIC_FOR_GCC_BUILTIN