[LLVM-C] Add binding to look up intrinsic by name

[CodaFi]

Summary

Add a binding to Function::lookupIntrinsicID so clients don't have to go searching the ID table themselves.

[whitequark]

LGTM

llvm/trunk/include/llvm-c/Core.h

 /**
  * Set the personality function attached to the function.
  *
  * @see llvm::Function::setPersonalityFn()
  */
 void LLVMSetPersonalityFn(LLVMValueRef Fn, LLVMValueRef PersonalityFn);
 
 /**
+ * Obtain the intrinsic ID number which matches the given function name.
+ *
+ * @see llvm::Function::lookupIntrinsicID()
+ */
+unsigned LLVMLookupIntrinsicID(const char *Name, size_t NameLen);
+
+/**
  * Obtain the ID number from a function instance.
  *
  * @see llvm::Function::getIntrinsicID()
  */
 unsigned LLVMGetIntrinsicID(LLVMValueRef Fn);
 
 /**
  * Create or insert the declaration of an intrinsic.  For overloaded intrinsics,

llvm/trunk/lib/IR/Core.cpp

const char *LLVMIntrinsicCopyOverloadedName(unsigned ID,
                                             size_t *NameLength) {
   auto IID = llvm_map_to_intrinsic_id(ID);
   ArrayRef<Type*> Tys(unwrap(ParamTypes), ParamCount);
   auto Str = llvm::Intrinsic::getName(IID, Tys);
   *NameLength = Str.length();
   return strdup(Str.c_str());
 }
 
+unsigned LLVMLookupIntrinsicID(const char *Name, size_t NameLen) {
+  return Function::lookupIntrinsicID({Name, NameLen});
+}
+
 LLVMBool LLVMIntrinsicIsOverloaded(unsigned ID) {
   auto IID = llvm_map_to_intrinsic_id(ID);
   return llvm::Intrinsic::isOverloaded(IID);
 }
 
 unsigned LLVMGetFunctionCallConv(LLVMValueRef Fn) {
   return unwrap<Function>(Fn)->getCallingConv();
 }