CmmLint error when doing safe ccall from cmm

[Simon Marlow]

On 20/06/2014 22:23, Yuras Shumovich wrote:
> Simon,
>
> Sorry if I'm too stupid, but
> do you mean we only support 64-bit results from "prim" call? But I'm
> using TO_W_ macro to convert the result to 64-bit value before returning
> from cmm function.

The result of your foreign call is a CInt, which is an I32.  If you make 
it an I64 and then convert it to an I32, that should work.

Cheers,
Simon

> Or you mean result from "ccall" call?
> nativeGen/X86/CodeGen.hs:genCCall64 definitely supports that. And it
> works for unsafe "ccall".
> Looks like the issue is somewhere in translation from high level cmm to
> low level cmm.
>
> Thanks,
> Yuras
>
> On Fri, 2014-06-20 at 21:24 +0100, Simon Marlow wrote:
>> On 20/06/14 15:03, Yuras Shumovich wrote:
>>> Hello,
>>>
>>> I'm trying to do safe ccall from cmm (see below for the code). It seems
>>> to work, but -dcmm-lint is not satisfied:
>>>
>>> /opt/ghc-7.8.2/bin/ghc --make -o test hs.hs cmm.cmm c.c -dcmm-lint -fforce-recomp
>>> Cmm lint error:
>>>     in basic block c4
>>>       in assignment:
>>>         _c1::I32 = R1;
>>>         Reg ty: I32
>>>         Rhs ty: I64
>>> Program was:
>>>     {offset
>>>       c5: _c0::I64 = R1;
>>>           _c2::I64 = c_test;
>>>           _c3::I32 = %MO_UU_Conv_W64_W32(_c0::I64);
>>>           I64[(young<c4> + 8)] = c4;
>>>           foreign call "ccall" arg hints:  []  result hints:  [] (_c2::I64)(...) returns to c4 args: ([_c3::I32]) ress: ([_c1::I32])ret_args: 8ret_off: 8;
>>>       c4: _c1::I32 = R1;
>>>           R1 = %MO_SS_Conv_W32_W64(_c1::I32);
>>>           call (P64[(old + 8)])(R1) args: 8, res: 0, upd: 8;
>>>     }
>>>
>>> <no location info>:
>>> Compilation had errors
>>
>> I believe we only support 64-bit results on a 64-bit platform, but we
>> you can always narrow to 32 bits with an MO_Conv afterwards if you want.
>>    This is essentially what happens when you call a function that returns
>> CInt using the FFI - you can always try that and see what Cmm you get.
>>
>> Also, I'll be mildly surprised if using safe foreign calls from
>> hand-written Cmm works, since I don't believe we use them anywhere so it
>> isn't likely to be well tested :-)
>>
>> Cheers,
>> Simon
>>
>>
>>> The same code without "safe" annotation passes cmm lint. Is it my error
>>> or ghc bug? How can I do safe ccall in cmm correctly?
>>>
>>> Here is the code:
>>>
>>> == c.c ==
>>> #include <assert.h>
>>>
>>> int c_test(int i)
>>> {
>>>     assert(i == 1);
>>>     return 2;
>>> }
>>>
>>> == cmm.cmm
>>> #include "Cmm.h"
>>>
>>> cmm_test(W_ i)
>>> {
>>>     CInt i1;
>>>     (i1) = ccall c_test(W_TO_INT(i)) "safe";
>>>     return (TO_W_(i1));
>>> }
>>>
>>> == hs.hs ==
>>> {-# LANGUAGE GHCForeignImportPrim #-}
>>> {-# LANGUAGE ForeignFunctionInterface #-}
>>> {-# LANGUAGE MagicHash #-}
>>> {-# LANGUAGE UnboxedTuples #-}
>>> {-# LANGUAGE UnliftedFFITypes #-}
>>>
>>> import GHC.Prim
>>> import GHC.Types
>>> import Control.Exception
>>>
>>> foreign import prim "cmm_test" test :: Int# -> Int#
>>>
>>> main :: IO ()
>>> main = do
>>>     let i1 = test 1#
>>>     assert (I# i1 == 2) (return ())
>>>
>>>
>>> Thanks,
>>> Yuras
>>>
>>>
>>> _______________________________________________
>>> ghc-devs mailing list
>>> ghc-devs at haskell.org
>>> http://www.haskell.org/mailman/listinfo/ghc-devs
>>>
>>
>
>