[LLVM-C] Upstream LLVMGetOrInsertFunction from rustc

Author: AMS21

llvm/include/llvm-c/Core.h

@@ -2988,6 +2988,22 @@ LLVM_C_ABI char *LLVMIntrinsicCopyOverloadedName2(LLVMModuleRef Mod,
  */
 LLVM_C_ABI LLVMBool LLVMIntrinsicIsOverloaded(unsigned ID);
 
+/**
+ * Obtain or insert a function into a module.
+ *
+ * If a function with the specified name already exists in the module, it
+ * is returned. Otherwise, a new function is created in the module with the
+ * specified name and type and is returned.
+ *
+ * The returned value corresponds to a llvm::Function instance.
+ *
+ * @see llvm::Module::getOrInsertFunction()
+ */
+LLVM_C_ABI LLVMValueRef LLVMGetOrInsertFunction(LLVMModuleRef M,
+                                                const char *Name,
+                                                size_t NameLen,
+                                                LLVMTypeRef FunctionTy);
+
 /**
  * Obtain the calling function of a function.
  *

llvm/lib/IR/Core.cpp

@@ -2523,6 +2523,14 @@ LLVMBool LLVMIntrinsicIsOverloaded(unsigned ID) {
   return llvm::Intrinsic::isOverloaded(IID);
 }
 
+LLVMValueRef LLVMGetOrInsertFunction(LLVMModuleRef M, const char *Name,
+                                     size_t NameLen, LLVMTypeRef FunctionTy) {
+  return wrap(unwrap(M)
+                  ->getOrInsertFunction(StringRef(Name, NameLen),
+                                        unwrap<FunctionType>(FunctionTy))
+                  .getCallee());
+}
+
 unsigned LLVMGetFunctionCallConv(LLVMValueRef Fn) {
   return unwrap<Function>(Fn)->getCallingConv();
 }