{-# LANGUAGE ForeignFunctionInterface #-} {- Ported from https://gcc.gnu.org/onlinedocs/jit/intro/tutorial01.html -} module Main (main) where import qualified GccJit import GccJit.Utils (release) import Foreign.Ptr import Foreign.C (CString, newCString) import System.Exit import System.IO type GreetFunction = CString -> IO () foreign import ccall "dynamic" mkFun :: FunPtr GreetFunction -> GreetFunction unwrapOrDie :: IO (Maybe a) -> String -> IO a unwrapOrDie x msg = do x' <- x case x' of Nothing -> die msg Just x'' -> return x'' createCode :: Ptr GccJit.Context -> IO () createCode ctxt = do {-  Let's try to inject the equivalent of:  void greet (const char *name)  {  printf ("hello %s\n", name);  }  -} voidType <- GccJit.contextGetType ctxt GccJit.Void constCharPtrType <- GccJit.contextGetType ctxt GccJit.ConstCharPtr paramName <- GccJit.contextNewParam ctxt nullPtr constCharPtrType "format" func <- GccJit.contextNewFunction ctxt nullPtr GccJit.FunctionExported voidType "greet" [paramName] False paramFormat <- GccJit.contextNewParam ctxt nullPtr constCharPtrType "format" intType <- GccJit.contextGetType ctxt GccJit.Int printFunc <- GccJit.contextNewFunction ctxt nullPtr GccJit.FunctionImported intType "printf" [paramFormat] True formatArg <- GccJit.contextNewStringLiteral ctxt "Hello %s!\n" nameArg <- GccJit.paramAsRValue paramName block <- unwrapOrDie (GccJit.functionNewBlock func Nothing) "NULL block" printCall <- GccJit.contextNewCall ctxt nullPtr printFunc [formatArg, nameArg] GccJit.blockAddEval block nullPtr printCall GccJit.blockEndWithVoidReturn block nullPtr main :: IO () main = do -- Get a "context" object for working with the library. ctxt <- unwrapOrDie GccJit.contextAcquire "NULL ctxt" -- Set some options on the context. -- Let's see the code being generated, in assembler form. GccJit.setBoolOption ctxt GccJit.DumpGeneratedCode True -- Populate the context. createCode ctxt -- Compile the code. result <- unwrapOrDie (GccJit.contextCompile ctxt) "NULL result" -- Extract the generated code from "result". greet <- unwrapOrDie (GccJit.resultGetCode result "greet") "NULL greet" -- Now call the generated function: worldStr <- newCString "World" mkFun greet worldStr hFlush stdout release ctxt release result