> StgCmmCon.hs:240 reads > ; return (mkRhsInit dflags reg lf_info hp_plus_n) } > > what's that got to do with pointer tagging?
If I understand correctly, mkRhsInit returns a tagged pointer: mkRhsInit :: DynFlags -> LocalReg -> LambdaFormInfo -> CmmExpr -> CmmAGraph mkRhsInit dflags reg lf_info expr = mkAssign (CmmLocal reg) (addDynTag dflags expr (lfDynTag dflags lf_info)) > But also we clearly must do so in the entry code for a data constructor Why? It's not clear to me. If every pointer to a constructor is tagged then maybe we don't need to enter constructors at all. 2016-08-25 15:41 GMT+00:00 Simon Peyton Jones <simo...@microsoft.com>: > StgCmmCon.hs:240 reads > ; return (mkRhsInit dflags reg lf_info hp_plus_n) } > > what's that got to do with pointer tagging? > > > But yes we need to do it in both places. Consider > > f x xs = let y = x:xs > in g y > > We should tag y before passing it to g. That's the StgCmmCon case. > > > But also we clearly must do so in the entry code for a data constructor > > > Simon > > | -----Original Message----- > | From: ghc-devs [mailto:ghc-devs-boun...@haskell.org] On Behalf Of Ömer > | Sinan Agacan > | Sent: 25 August 2016 11:46 > | To: ghc-devs <ghc-devs@haskell.org> > | Subject: Can we mark DataCon ptrs only in allocation sites and not > | generate entry code? > | > | As far as I can see in the native code compiler we mark DataCon > | pointers in two places: > | > | 1. In allocation sites (StgCmmCon.hs:240) > | 2. In DataCon entry code (StgCmm.hs:244) > | > | I was wondering why we can't get away with just doing (1). Can anyone > | give me > | an example where an allocation doesn't return a tagged pointer and we > | need to > | tag it in entry code? If every allocation returns a tagged pointer, > | then why do > | we need (2) ? > | > | Thanks > | _______________________________________________ > | ghc-devs mailing list > | ghc-devs@haskell.org > | https://na01.safelinks.protection.outlook.com/?url=http%3a%2f%2fmail.h > | askell.org%2fcgi-bin%2fmailman%2flistinfo%2fghc- > | devs&data=01%7c01%7csimonpj%40microsoft.com%7cb1571fb2c4e24941998308d3 > | ccd519bb%7c72f988bf86f141af91ab2d7cd011db47%7c1&sdata=ilDdLBFdfvzY1g6Z > | iuHyY6W%2bOIq2Y69f5YTgmpqwRO8%3d _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs