StgRhsClosure freevar and argument name duplicates
Csaba Hruska
csaba.hruska at gmail.com
Tue Nov 6 11:19:51 UTC 2018
Correction: I've also noticed that there are two Main.main top-level
binders in the generated STG with different uniques.
On Tue, Nov 6, 2018 at 12:19 PM Csaba Hruska <csaba.hruska at gmail.com> wrote:
> I've also noticed that there are two Main.main top-level binders in the
> generated STG with different uniques?
> And GHC produces a working executable.
> Is Main.main an exception or does top-level names have some kind of
> "should be exported" property?
>
> On Tue, Nov 6, 2018 at 12:02 PM Simon Peyton Jones <simonpj at microsoft.com>
> wrote:
>
>> I think top level names should be unique in occ-names; because those
>> occ-names generate the symbols in the binary.
>>
>>
>>
>> Simon
>>
>>
>>
>> *From:* Csaba Hruska <csaba.hruska at gmail.com>
>> *Sent:* 06 November 2018 11:01
>> *To:* Simon Peyton Jones <simonpj at microsoft.com>
>> *Cc:* ghc-devs at haskell.org
>> *Subject:* Re: StgRhsClosure freevar and argument name duplicates
>>
>>
>>
>> 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%7Cd47aada6162e4c2da86608d643d720dd%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636770988594092291&sdata=re0I7r77Hli0UuEv07vBNRRrWttdDLGE8BaYYQZNr8o%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%7Cd47aada6162e4c2da86608d643d720dd%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636770988594102189&sdata=sEVZfZHmc9%2BQxzp8bQijgiRBPvGv5U0lsQi9lElUoj8%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%7Cd47aada6162e4c2da86608d643d720dd%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636770988594102189&sdata=KaYvZjgoFE%2BNT%2FbQ4mZlKqB8Q%2FT50CUstmJS3RGtur0%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%7Cd47aada6162e4c2da86608d643d720dd%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636770988594112198&sdata=baugV3HdRfINk51GmbD51LtoW1A3S7p4yKXvIXseEgA%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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