When iselExpr64 (CmmLit (CmmInt i _)) is used?

[Austin Seipp]

Hi Karel,

Although I haven't looked extremely closely, may I suggest perhaps
writing your test case in C-- instead of Haskell? It looks like you
can trigger this simply with a CmmAssign or CmmStore node with a 64bit
type, which will call assign(Reg|Mem)_I64Code, in turn calling
iselExpr64 - see nativeGen/SPARC/CodeGen.hs:stmtToInstrs (line 121).
If you trace through from CmmParse.y to find emitAssign in
StgCmmMonad, it'll create an assignment node for you.

Do that with -S and check out the assembly files (-ddump-asm should
also do the trick).

This should make it easy to trigger and examine. Then you can link it
into a Haskell program as a foreign primop and test it extensively
with a working executable.



On Sat, Mar 1, 2014 at 12:12 PM, Karel Gardas <karel.gardas at centrum.cz> wrote:
>
> Hello,
>
> I'm trying to resurrect SPARC NCG. I've switched it on and basically
> provided functions on which NCG has panic during the build, basically just 2
> were missing so far (cut from git diff):
>
> +genCCall (PrimTarget MO_Touch) _ _
> + = return $ nilOL
> +
>
>
> +iselExpr64 (CmmLit (CmmInt i _)) = do
> +  (rlo, rhi) <- getNewRegPairNat II32
> +  let
> +      half0 = fromIntegral (fromIntegral i :: Word32)
> +      half1 = fromIntegral (fromIntegral (i `shiftR` 32) :: Word32)
> +      code = toOL [
> +              SETHI (HI $ ImmInt half0) rlo,
> +              OR False rlo (RIImm (LO $ ImmInt half0)) rlo,
> +              SETHI (HI $ ImmInt half1) rhi,
> +              OR False rhi (RIImm (LO $ ImmInt half1)) rhi
> +             ]
> +  return (ChildCode64 code rlo)
>
>
> Now, my ghc-stage2 badly fails and testsuite run with stage=1 reveals 1390
> unexpected failures. Perhaps this is unrelated, but still I'd like to test
> that my iselExpr64 implementation above is correct. Is there any simple
> haskell code which makes this function in NCG run? I'm trying this:
>
> import GHC.Prim
> import GHC.Exts
>
> main = do
>         let x = 18446744073709551615#
>         --- 2^64-1 = 18446744073709551615
>         putStrLn (show $ I# x)
>         return()
>
>
> I've had a hope that unboxed long int constant is what causes iselExpr64
> being called, but generated assembly looks suspicious -- like it's not
> called so my idea was wrong here probably. Do you have any idea how to test
> this function and see its generated assembly?
>
> BTW: I hope I got the function semantics correct as a loading of 64bit
> constant/integer into a pair of 32bits registers...
>
> Thanks a lot!
> Karel
>
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-- 
Regards,

Austin Seipp, Haskell Consultant
Well-Typed LLP, http://www.well-typed.com/