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

[Karel Gardas]

Hi Austin,

thanks for your suggestion. Unfortunately this completely go over my 
head now. :-) I'm not able to write single line of C-- test yet. Anyway, 
I've tackled this from different side: added debugging message to the 
function and then see where it's emitted while building GHC, it looks 
like GHC.Word.hs from base library is my friend here. I've also have a 
look into generated asm and it looks reasonable so I think my 
implementation of iselExpr64 is correct.

Thanks!
Karel

On 03/ 1/14 09:26 PM, Austin Seipp wrote:
> 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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>
>
>