Hi Carter,

I didn't write this assertion. I only validated locally (IIRC at the time I uploaded the diff, harbormaster was failing for some other reasons).

I'll try to have a look at it this weekend.

Cheers!

- Michal

On Wed, Jul 25, 2018 at 2:16 AM Carter Schonwald <carter.schonwald@gmail.com> wrote:
Michal: did you write this Assert about width? and if so could you explain it so we can understand?

hrmm... that code is in the procedure for generating C calls for 64bit  intel systems
https://github.com/michalt/ghc/blob/int8/compiler/nativeGen/X86/CodeGen.hs#L2541 is the  top of that routine

and width is defined right below the spot in question
https://github.com/michalt/ghc/blob/int8/compiler/nativeGen/X86/CodeGen.hs#L2764-L2774

it seems like the code/assertion likely predates michal's work? (eg, a trick to make sure that genCCall64 doesn't get invoked by 32bit platforms?)

On Mon, Jul 23, 2018 at 8:54 PM Abhiroop Sarkar <asiamgenius@gmail.com> wrote:
Hi Michal,

In the tests that you have added to D4475, are all the tests running fine?

On my machine, I was running the FFI tests(https://github.com/michalt/ghc/blob/int8/testsuite/tests/ffi/should_run/PrimFFIInt8.hs)  and they seem to fail at a particular assert statement in the code generator.


Upon commenting that assert the tests run fine. Am I missing something or is the failure expected?

Thanks,
Abhiroop

On Mon, Jul 9, 2018 at 8:31 PM Michal Terepeta <michal.terepeta@gmail.com> wrote:
Just for the record, I've uploaded the changes to binary:

- Michal

On Wed, Jul 4, 2018 at 11:07 AM Michal Terepeta <michal.terepeta@gmail.com> wrote:
Yeah, if you look at the linked diff, there are a few tiny changes to binary that are necessary.

I'll try to upload them to github later this week.

Ben, is something blocking the review of the diff? I think I addressed all comments so far.

- Michal

On Wed, Jul 4, 2018 at 1:38 AM Abhiroop Sarkar <asiamgenius@gmail.com> wrote:
Hello Michal,

I was looking at your diff https://phabricator.haskell.org/D4475  and there seems to be some changes that you perhaps made in the binary package (https://phabricator.haskell.org/differential/changeset/?ref=199152&whitespace=ignore-most). I could not find your version of binary on your github repos list. Is it possible for you to upload that so I can pull those changes?

Thanks

Abhiroop

On Mon, May 28, 2018 at 10:45 PM Carter Schonwald <carter.schonwald@gmail.com> wrote:
Abhiroop has the gist, though the size of word args for simd is more something we want to be consistent between 32/64 bit modes aka ghc targeting 32 or 64 bit intel with simd support :).  It would be best if the unpack and pack operations that map to and from unboxed tuples where consistent and precise type wise. 



-Carter

On May 28, 2018, at 5:02 PM, Abhiroop Sarkar <asiamgenius@gmail.com> wrote:

Hello Michal,

My understanding of the issues are much lesser compared to Carter. However, I will state whatever I understood from discussions with him. Be warned my understanding might be wrong and Carter might be asking this for some completely different reason.

> Out of curiosity, why do you need Word64#/Word32# story to be fixed for SIMD?

One of the issues we are dealing with is multiple microarchitectures(SSE, AVX, AVX2 etc). As a result different microarchitectures has different ways of handling an 8 bit or 16 bit or 32 bit unsigned integer. An example I can provide is the vector multiply instruction which has different semantics of multiplying and storing the first 16 bits of a 32 bit unsigned integer compared to the lower 16 bits for each of the elements in its SIMD registers. There will be some other intricacies around handling a byte sized integer or a 64 bit integer which will be different from the 32 bit version. 

Basically a 128 bit vector instruction will make some minor differences when dealing with 2 64 bit integers or 4 32 bit integer or 8 16 bit integers.

So I think at the higher level we would want to be as precise as possible when specifying the datatypes and want things like Word8#, Word16#, Word32#, Word64# rather than a single ambiguous type like Word.

One more example is this vector operation like : broadcastWord64X2# :: Word# -> Word64X2# which should rather be broadcastWord64X2# :: Word64# -> Word64X2#

Another reason could be improving the space efficiency of packing various datatypes. This was explained in some detail in this comment: https://github.com/ghc-proposals/ghc-proposals/pull/74#issuecomment-333951559

Thanks,
Abhiroop

On Mon, May 28, 2018 at 6:06 PM, Michal Terepeta <michal.terepeta@gmail.com> wrote:
Hey Carter,

Yeah, I'm totally snowed under with personal stuff at the moment, so not much time to hack on
anything. I've managed to make some progress on https://phabricator.haskell.org/D4475 (prototype
that adds Int8#/Word8#; waiting for another round of review). Sadly June still looks a bit crazy for
me, so I can't promise anything for Word64#/Word32# (and Int64#/Int32#). I hope to have some more
time in July.

If this is blocking you, then please don't wait for me and go ahead (my diff for Int8#/Word8# might
be a decent starting point to see which places might need changes).

Out of curiosity, why do you need Word64#/Word32# story to be fixed for SIMD? Cmm already has
separate types for vector types (see TyCon.hs and VecRep constructor of PrimRep).

Cheers!

- Michal

PS. Are you coming to ZuriHac by any chance?

On Mon, May 28, 2018 at 12:37 AM Carter Schonwald <carter.schonwald@gmail.com> wrote:
Hey Michal!
So i'm mentoring Abhiroop around getting SIMD all nice and awesome, and I realized we still dont quite yet have the nice Word32# and Word64# etc story in ghc as yet.

Whats the status on that and or is there a way we can help get that over the hump for ghc? These different sized in register ints and friends have a tight partnership with any nice SIMD iterating over the summer, and hopefully helps inform the design 

-Carter



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