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    "# Remote Backend Compiler - RBC\n",
    "*by Pearu Peterson*\n",
    "\n",
    "## Statement of the problem\n",
    "\n",
    "*Compile and run user-defined functions in a language-agnostic JIT enabled program semi-remotely.*\n",
    "\n",
    "### Semi-remote compilation\n",
    "\n",
    "- *compiler frontend*: user-written source code is parsed and transformed to LLVM IR in client program\n",
    "- the client program sends the LLVM IR over network to a server program\n",
    "- *compiler backend*: the server program compiles the LLVM IR to machine code (that can be executed on the server's CPU or GPU devices)\n",
    "\n",
    "### Constraints\n",
    "\n",
    "- A user-defined function is defined in Python or C/C++\n",
    "  (or any other language with LLVM tools)\n",
    "- Client host runs on a 32- or 64-bit OS: Linux, MacOSX, Windows\n",
    "- Server host runs on a 64-bit Linux\n",
    "\n",
    "## Solution\n",
    "\n",
    "- *Remote Backend Compiler - RBC*: https://github.com/xnd-project/rbc\n",
    "- A Python-to-Python prototype uses Numba for LLVM IR generation and Numba llvmlite for machine code compilation\n",
    "- A Python-to-SQL application uses Numba for LLVM IR generation and HeavyDB for machine code compilation\n",
    "  * HeavyDB is a GPU enabled SQL database server\n",
    "  * HeavyDB uses LLVM Compiler C++ library for JIT compilation\n",
    "  * https://www.heavy.ai/\n",
    "\n",
    "# Demo of the prototype below"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "staring rpc.thrift server: /home/pearu/git/xnd-project/rbc/rbc/remotejit.thrift"
     ]
    }
   ],
   "source": [
    "#NBVAL_IGNORE_OUTPUT\n",
    "from rbc import RemoteJIT\n",
    "rjit = RemoteJIT(host='localhost', port=7890)\n",
    "rjit.start_server(background=True)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Client-server connector, RBC jit-decorator\n",
    "rjit = RemoteJIT(host='localhost', port=7890)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [],
   "source": [
    "# A user-defined function\n",
    "@rjit('int64(int64, int64)')\n",
    "def foo(a, b):\n",
    "    return a + b"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      "--------------------------------------cpu---------------------------------------\n",
      "; ModuleID = 'rbc.irtools.compile_to_IR'\n",
      "source_filename = \"<string>\"\n",
      "target triple = \"x86_64-unknown-linux-gnu\"\n",
      "\n",
      "@_ZN08NumbaEnv8__main__7foo_241B40c8tJTC_2fWQA9HW1CcAv0EjzIkAdRoAEtoAgA_3dExx = common local_unnamed_addr global i8* null\n",
      "\n",
      "; Function Attrs: norecurse nounwind readnone\n",
      "define i64 @foo_lallA(i64 %.1, i64 %.2) local_unnamed_addr #0 {\n",
      "entry:\n",
      "  %.6.i = add nsw i64 %.2, %.1\n",
      "  ret i64 %.6.i\n",
      "}\n",
      "\n",
      "attributes #0 = { norecurse nounwind readnone }\n",
      "\n",
      "!llvm.module.flags = !{!0}\n",
      "\n",
      "!0 = !{i32 4, !\"pass_column_arguments_by_value\", i1 false}\n",
      "\n",
      "--------------------------------------------------------------------------------\n"
     ]
    }
   ],
   "source": [
    "# NBVAL_IGNORE_OUTPUT\n",
    "# Generate LLVM IR, useful for debugging\n",
    "print(foo)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "4"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Triggers:\n",
    "#  - local frontend compile,\n",
    "#  - remote backend compile,\n",
    "#  - and remote call\n",
    "foo(1, 3)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "6"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "foo(2, 4)  # reuses remote compile result and triggers remote call"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "found no matching function signature to given argument types:\n",
      "    (float64, float64) -> ...\n",
      "  available function signatures:\n",
      "    int64(int64, int64)\n"
     ]
    }
   ],
   "source": [
    "try:\n",
    "    foo(1.2, 3.4)\n",
    "except Exception as msg:\n",
    "    print(msg)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [],
   "source": [
    "# update with new signatures\n",
    "foo.signature('double(double, double)')\n",
    "foo.signature('complex128(complex128, complex128)');"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "(1+3.4j)"
      ]
     },
     "execution_count": 9,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "foo(1, 3.4j)  # triggers remote compile and call"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "4.2"
      ]
     },
     "execution_count": 10,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "foo(1.2, 3)  # triggers remote compile and call"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [],
   "source": [
    "rjit.stop_server()"
   ]
  }
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