StgRhsClosure freevar and argument name duplicates
Csaba Hruska
csaba.hruska at gmail.com
Tue Nov 6 11:00:42 UTC 2018
My plan is to extend GHC's STG linter to check the following properties:
- uniqueness of free var and arg list of StgRhsClosure
- top level binding name uniqueness
I'll patch my local GHC 8.2.2 and GHC HEAD. I'll also attach the patch to
the ticket.
I have a question regarding top level names.
Should the top-level names be unique as occ names or just in unique values?
If not, then what is the rule?
Thanks,
Csaba
On Tue, Nov 6, 2018 at 11:13 AM Simon Peyton Jones <simonpj at microsoft.com>
wrote:
> Does this happen in HEAD with GHC’s own STG printer? If so, could you
> file a Trac ticket – it’s clearly wrong.
>
>
>
> But I do wonder if it could perhaps be something to do with your branch?
>
>
>
> Thanks
>
>
>
> Simon
>
>
>
> *From:* Csaba Hruska <csaba.hruska at gmail.com>
> *Sent:* 05 November 2018 16:33
> *To:* Simon Peyton Jones <simonpj at microsoft.com>
> *Cc:* ghc-devs at haskell.org
> *Subject:* Re: StgRhsClosure freevar and argument name duplicates
>
>
>
> Correction!
>
> The problem happens in integer-gmp:
>
> https://github.com/ghc/ghc/blob/master/libraries/integer-gmp/src/GHC/Integer/Type.hs#L761-L770
> <https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fghc%2Fghc%2Fblob%2Fmaster%2Flibraries%2Finteger-gmp%2Fsrc%2FGHC%2FInteger%2FType.hs%23L761-L770&data=02%7C01%7Csimonpj%40microsoft.com%7C0a8467d53f9145e88f9208d6433c6e0e%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636770324161848413&sdata=SQrzwfSloPvCTaEAUd4M3PVHanfjX37xjdRE6BXn2Pc%3D&reserved=0>
>
>
>
> On Mon, Nov 5, 2018 at 5:27 PM Csaba Hruska <csaba.hruska at gmail.com>
> wrote:
>
> An example for the duplication please check the divModInteger
> <https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fghc%2Fghc%2Fblob%2Fmaster%2Flibraries%2Finteger-simple%2FGHC%2FInteger%2FType.hs%23L373-L380&data=02%7C01%7Csimonpj%40microsoft.com%7C0a8467d53f9145e88f9208d6433c6e0e%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636770324161858421&sdata=Tqq7MeFA91LqKwitneuRxoDVwO8EAhWBY%2FN5RmdA4Bg%3D&reserved=0>
> function from integer-simple GHC.Integer.Type.
>
> The STG (GHC 8.2.2) generated from *divModInteger* *::** Integer ->
> Integer -> (# Integer, Integer #) *contains duplications in a closure
> binder list.
>
>
>
> Using my custom STG printer it looks like:
>
> module GHC.Integer.Type where
>
>
>
> using GHC.Prim
> using GHC.Tuple
> using GHC.Types
>
>
>
> GHC.Integer.Type.divModInteger {-083-} =
> closure (F:) (B:
> n.s84123 {-s84123-}
> d.s84124 {-s84124-}) {
> case GHC.Integer.Type.quotRemInteger {-084-}
> n.s84123 {-s84123-}
> d.s84124 {-s84124-}
> of qr.s84125 {-s84125-} {
> GHC.Prim.(#,#) {-86-} ipv.s84126 {-s84126-} ipv1.s84127 {-s84127-} ->
> let $j.s84128 {-s84128-} =
> closure (F:
> d.s84124 {-s84124-}
> * ipv.s84126 {-s84126-}*
> * ipv1.s84127 {-s84127-}*
> * ipv.s84126 {-s84126-}*
> *ipv1.s84127 {-s84127-}*) (B:
> wild.s84129 {-s84129-}) {
> let $j1.s84130 {-s84130-} =
> closure (F:
> d.s84124 {-s84124-}
> ipv.s84126 {-s84126-}
> ipv1.s84127 {-s84127-}
> ipv.s84126 {-s84126-}
> ipv1.s84127 {-s84127-}
> wild.s84129 {-s84129-}) (B:
> wild1.s84131 {-s84131-}) {
> case _stg_prim_negateInt#
> wild.s84129 {-s84129-}
> of sat.s84132 {-s84132-} {
> DEFAULT ->
> case _stg_prim_==#
> wild1.s84131 {-s84131-}
> sat.s84132 {-s84132-}
> of sat.s84133 {-s84133-} {
> DEFAULT ->
> case _stg_prim_tagToEnum#
> sat.s84133 {-s84133-}
> of wild2.s84134 {-s84134-} {
> GHC.Types.False {-612-} ->
> GHC.Prim.(#,#) {-86-}
> ipv.s84126 {-s84126-}
> ipv1.s84127 {-s84127-}
> GHC.Types.True {-645-} ->
> case GHC.Integer.Type.plusInteger {-066-}
> ipv1.s84127 {-s84127-}
> d.s84124 {-s84124-}
> of r'.s84135 {-s84135-} {
> DEFAULT ->
> case GHC.Integer.Type.plusInteger {-066-}
> ipv.s84126 {-s84126-}
> GHC.Integer.Type.lvl11 {-r50574-}
> of q'.s84136 {-s84136-} {
> DEFAULT ->
> GHC.Prim.(#,#) {-86-}
> q'.s84136 {-s84136-}
> r'.s84135 {-s84135-}
> }
> }
> }
> }
> }}
>
> in case ipv1.s84127 {-s84127-}
> of wild1.s84137 {-s84137-} {
> GHC.Integer.Type.S# {-621-} i#.s84138 {-s84138-} ->
> case _stg_prim_<#
> i#.s84138 {-s84138-} 0#
> of sat.s84140 {-s84140-} {
> DEFAULT ->
> case _stg_prim_>#
> i#.s84138 {-s84138-} 0#
> of sat.s84139 {-s84139-} {
> DEFAULT ->
> case _stg_prim_-#
> sat.s84139 {-s84139-}
> sat.s84140 {-s84140-}
> of sat.s84141 {-s84141-} {
> DEFAULT ->
> $j1.s84130 {-s84130-}
> sat.s84141 {-s84141-}
> }
> }
> }
> GHC.Integer.Type.Jp#
> <https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2FGHC.Integer.Type.Jp%23&data=02%7C01%7Csimonpj%40microsoft.com%7C0a8467d53f9145e88f9208d6433c6e0e%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636770324161868430&sdata=ajvn3QOaaWDYGqqTKtPe4fYTJaNHGVGmFsfuKN1Psyo%3D&reserved=0>
> {-r5813-} dt.s84142 {-s84142-} ->
> $j1.s84130 {-s84130-} 1#
> GHC.Integer.Type.Jn# {-r5814-} dt.s84143 {-s84143-} ->
> $j1.s84130 {-s84130-} -1#
> }}
>
> in case d.s84124 {-s84124-}
> of wild.s84144 {-s84144-} {
> GHC.Integer.Type.S# {-621-} i#.s84145 {-s84145-} ->
> case _stg_prim_<#
> i#.s84145 {-s84145-} 0#
> of sat.s84147 {-s84147-} {
> DEFAULT ->
> case _stg_prim_>#
> i#.s84145 {-s84145-} 0#
> of sat.s84146 {-s84146-} {
> DEFAULT ->
> case _stg_prim_-#
> sat.s84146 {-s84146-}
> sat.s84147 {-s84147-}
> of sat.s84148 {-s84148-} {
> DEFAULT ->
> $j.s84128 {-s84128-}
> sat.s84148 {-s84148-}
> }
> }
> }
> GHC.Integer.Type.Jp#
> <https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2FGHC.Integer.Type.Jp%23&data=02%7C01%7Csimonpj%40microsoft.com%7C0a8467d53f9145e88f9208d6433c6e0e%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636770324161868430&sdata=ajvn3QOaaWDYGqqTKtPe4fYTJaNHGVGmFsfuKN1Psyo%3D&reserved=0>
> {-r5813-} dt.s84149 {-s84149-} ->
> $j.s84128 {-s84128-} 1#
> GHC.Integer.Type.Jn# {-r5814-} dt.s84150 {-s84150-} ->
> $j.s84128 {-s84128-} -1#
> }
> }}
>
>
>
> On Mon, Nov 5, 2018 at 2:08 PM Simon Peyton Jones <simonpj at microsoft.com>
> wrote:
>
> I don’t think there should be duplicates in either. Do you have a test
> case that shows duplicates?
>
>
>
> Simon
>
>
>
> *From:* ghc-devs <ghc-devs-bounces at haskell.org> *On Behalf Of *Csaba
> Hruska
> *Sent:* 04 November 2018 11:22
> *To:* ghc-devs at haskell.org
> *Subject:* Re: StgRhsClosure freevar and argument name duplicates
>
>
>
> Is it possible that GHC generates STG with invalid binding semantics for
> certain cases that the Cmm codegen fix or ignore?
>
> This could explain my observations.
>
> I've checked the Stg linter source (StgLint.hs ; GHC 8.2.2 and github
> master) and it does not check StgRhsClosure free var and binder list at all.
>
> And the scope checker function (addInScopeVars) does not check for
> duplicates.
>
>
>
> Any thoughts?
>
>
>
> Cheers,
>
> Csaba
>
>
>
> On Sat, Nov 3, 2018 at 9:53 AM Csaba Hruska <csaba.hruska at gmail.com>
> wrote:
>
> Hi,
>
>
>
> Can StgRhsClosure's freevar list ([occ]) or argument list ([bndr]) contain
> duplicates?
>
>
>
> Cheers,
>
> Csaba
>
>
>
> data GenStgRhs bndr occ
> = StgRhsClosure
> CostCentreStack -- CCS to be attached (default is
> CurrentCCS)
> StgBinderInfo -- Info about how this binder is used (see
> below)
> *[occ]* -- non-global free vars; a list, rather
> than
> -- a set, because order is important
> !UpdateFlag -- ReEntrant | Updatable | SingleEntry
> *[bndr]* -- arguments; if empty, then not a
> function;
> -- as above, order is important.
> (GenStgExpr bndr occ) -- body
>
>
>
>
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