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Diffstat (limited to 'compiler/NOTES')
| -rw-r--r-- | compiler/NOTES | 156 |
1 files changed, 0 insertions, 156 deletions
diff --git a/compiler/NOTES b/compiler/NOTES deleted file mode 100644 index 645d27eaed..0000000000 --- a/compiler/NOTES +++ /dev/null @@ -1,156 +0,0 @@ -More type functions -~~~~~~~~~~~~~~~~~~~ -* Allow {tv = TYPE ty) as a non-rec binding in Core -* Use this to make equality constraints more uniform -* Can a Dict can contain an EqPred? - How does that differ from an EqInst? -* Make DictBinds into Core - -* In zonking, do we need to zonk the kinds of coercion variables? - -Type functions -~~~~~~~~~~~~~~ -* A Given inst should be a CoVar, not a coercion - -* finaliseEqInst should not need to call zonk - -* Why do we need fromGivenEqDict? How could we construct - a Dict that had an EqPred? - newDictBndr should make an EqInst directly - -* tc_co should be accessed only inside Inst - -* Inst.mkImplicTy needs a commment about filtering out EqInsts - How *do* we deal with wanted equalities? - -* Inst.instType behaves inconsistently for EqInsts: it should - return an EqPred, like the instType' hack in pprDictsTheta - - Consequences: adjust the uses of instType in TcSimplify - -* tcDeref* functions are unused, except in tcGenericNormalizeFamInst, when - we can equally well use TcMType.lookupTcTyVar - -* Coercion.mkEqPredCoI looks very peculiar. - - - - -------------------------- -*** unexpected failure for jtod_circint(opt) - - - New back end thoughts - ------------------------------------------------------------------------------ -Codegen notes - -* jumps to ImpossibleBranch should be removed. - -* Profiling: - - when updating a closure with an indirection to a function, - we should make a permanent indirection. - - - check that we're bumping the scc count appropriately - -* check perf & binary sizes against the HEAD - ------------------------------------------------------------------------------ -C backend notes - -* use STGCALL macros for foreign calls (doesn't look like volatile regs - are handled properly at the mo). - ------------------------------------------------------------------------------ -Cmm parser notes - -* switches - -* need to cater for unexported procedures/info tables? - -* We should be able to get rid of entry labels, use info labels only. - - we need a %ENTRY_LBL(info_lbl) macro, so that instead of - JMP_(foo_entry) we can write jump %ENTRY_LBL(foo_info). - ------------------------------------------------------------------------------ - -* Move arg-descr from LFInfo to ClosureInfo? - But: only needed for functions - -* Move all of CgClosure.link_caf into NewCaf, and newDynCaf - -* If the case binder is dead, and the constr is nullary, - do we need to assign to Node? - - -------------------------------- -NB: all floats are let-binds, but some non-rec lets - may be unlifted (with RHS ok-for-speculation) - - -simplArg: [use strictness] - [used for non-top-lvl non-rec RHS or function arg] - if strict-type || demanded - simplStrictExpr - else - simplExpr ---> (floats,expr) - float all the floats if exposes constr app, return expr - -simpl (applied lambda) ==> simplNonRecBind -simpl (Let (NonRec ...) ..) ==> simplNonRecBind - -simpl (Let (Rec ...) ..) ==> simplRecBind - -simplRecBind: - simplify binders (but not its IdInfo) - simplify the pairs one at a time - using simplRecPair - -simplNonRecBind: [was simplBeta] - [used for non-top-lvl non-rec bindings] - - check for PreInlineUnconditionally - - simplify binder, including its IdInfo - - simplArg - - if strict-type - addCaseBind [which makes a let if ok-for-spec] - else - completeLazyBind - -simplLazyBind: [binder already simplified, but not its IdInfo] - [used for both rec and top-lvl non-rec] - [must not be strict/unboxed; case not allowed] - - check for PreInlineUnconditionally - - substituteIdInfo and add result to in-scope - [so that rules are available in rec rhs] - - simplExpr --> (floats,expr) - - float: lifted floats only - if exposes constructor or pap (even if non-triv args) - or if top level - - completeLazyBind - - -completeLazyBind: [given a simplified RHS] - [used for both rec and non-rec bindings, top level and not] - - try discarding dead - - try PostInlineUnconditionally - - let-bind coerce arg and repeat - - try rhs tylam (float) - - try eta expand (float) [not if any float is unlifted && (non-spec || top_lvl || rec)] - - let-bind constructor args [not if any float is ..as above..] - - - add unfolding [this is the only place we add an unfolding] - add arity - - - - -Eta expansion -~~~~~~~~~~~~~~ -For eta expansion, we want to catch things like - - case e of (a,b) -> \x -> case a of (p,q) -> \y -> r - -If the \x was on the RHS of a let, we'd eta expand to bring the two -lambdas together. And in general that's a good thing to do. Perhaps -we should eta expand wherever we find a (value) lambda? Then the eta -expansion at a let RHS can concentrate solely on the PAP case. |