-Notes July 00
-~~~~~~~~~~~~~~
-Time.lhs: fails with too many arguments to C function
-works with native code gen
-
-CTypes.lhs: fails with
- /tmp/ghc2840.hc:42413: fixed or forbidden register 3 (bx) was spilled for class GENERAL_REGS.
- This may be due to a compiler bug or to impossible asm statements or clauses.
-works without -O
-
-posix/* fails with
- ghc1653.c:4: `#include' expects "FILENAME" or <FILENAME>
- ghc1653.c:6: `#include' expects "FILENAME" or <FILENAME>
-works when one fixes the makefile
-
-make depend needs the -osuf o removed.
-
-CTypes also has a Subst-worker WARNING.
-
-
-Notes June 99
-~~~~~~~~~~~~~
-* In nofib/spectral/mandel2/Main.check_radius, there's a call to (fromIntegral m), where
- m is defined at top level. The full-laziness pass doesn't catch this because by
- the time it runs, enough inlining has happened that it looks like
- case ccall ... of (# a,b #) -> ...
- and the full laziness pass doesn't float unboxed things.
-
-* The same function is an excellent example of where liberate-case would be a win.
-
-* Don't forget to try CSE
-
-Interface files
-~~~~~~~~~~~~~~~
-* Don't need to pin a kind on the type variable in a interface class decl,
- because it'll be correctly re-inferred when we read it in.
-
-* The double semicolon at the end of an interface-file signature is so that
- the lexer can run through the pragmas very fast when -O isn't being used.
-
-* In export lists, T|(A,B) says that constructors A and B are exported,
- but not the type T. Similarly for classes.
- We can't say T(T,A,B) and T(A,B) to export or not-export T respectively,
- because the type T might have a constructor T.
-
+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
+
+simplRecPair: [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
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