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
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