Repository : ssh://darcs.haskell.org//srv/darcs/ghc On branch : supercompiler
http://hackage.haskell.org/trac/ghc/changeset/680f9313ab06eb12f21d7c46d7612d88dfd8b31d >--------------------------------------------------------------- commit 680f9313ab06eb12f21d7c46d7612d88dfd8b31d Author: Max Bolingbroke <batterseapo...@hotmail.com> Date: Tue Oct 23 18:00:46 2012 +0100 Weaken the bugcheck for typegen tieback memo >--------------------------------------------------------------- .../supercompile/Supercompile/Drive/Process3.hs | 9 ++++++--- 1 files changed, 6 insertions(+), 3 deletions(-) diff --git a/compiler/supercompile/Supercompile/Drive/Process3.hs b/compiler/supercompile/Supercompile/Drive/Process3.hs index 1b2bec9..e23b919 100644 --- a/compiler/supercompile/Supercompile/Drive/Process3.hs +++ b/compiler/supercompile/Supercompile/Drive/Process3.hs @@ -661,7 +661,7 @@ memo opt init_state = {-# SCC "memo'" #-} memo_opt init_state -- This means that we preferred to roll back to something which gives an MSG with the *smallest possible* renaming (i.e. is more specific). -- This is the opposite of what I've implemented below (FIXME). -- TODO: maybe it actually would be OK (for SC termination) to roll back to h0 at (*)? Though it would mean dumping any tiebacks to h2 unnecessarily. - moreSpecific (RightGivesTypeGen _ _ _rn_l) (RightGivesTypeGen _ _ _rn_r) + moreSpecific (RightGivesTypeGen _ _s_l rn_l) (RightGivesTypeGen _ _s_r rn_r) -- OK, here is what I have concluded after long thought. -- As long as we DON'T CREATE A PROMISE when type generalising, then there will be a always be a maximum of one -- possible type generalisation. A simple example demonstrates the principal behind this. Imagine that there were two @@ -678,12 +678,15 @@ memo opt init_state = {-# SCC "memo'" #-} memo_opt init_state -- type generalise it against the earlier promise (i.e. f Int Char) and hence would have driven (f alpha beta) without -- recording (f Float Bool). Now when we come to supercompile (f Int Bool) we can just tie back to (f alpha beta), -- which is absolutely what we want. - = error "moreSpecific: two possible type gens, this should not happen!" -- renamingSize rn_r <= renamingSize rn_l + | pREINITALIZE_MEMO_TABLE + = renamingSize rn_r <= renamingSize rn_l -- NB: although the argument above *is* true, we can have two type-genable promises due to memoiser preinit! + | otherwise + = pprPanic "moreSpecific: two possible type gens, this should not happen!" (ppr rn_l $$ ppr rn_r $$ pPrintFullState quietStatePrettiness _s_l $$ pPrintFullState quietStatePrettiness _s_r) -- Prefer instance matches to type generalisation (don't have a good sense about what is best here): moreSpecific (RightIsInstance _ _ _) _ = True moreSpecific _ (RightIsInstance _ _ _) = False - --renamingSize (_, tv_subst, co_subst) = sumMap typeSize (varEnvElts tv_subst) + sumMap coercionSize (varEnvElts co_subst) + renamingSize (_, tv_subst, co_subst) = sumMap typeSize (varEnvElts tv_subst) + sumMap coercionSize (varEnvElts co_subst) -- TODO: it might be OK to insist the incoming renaming is invertible, but this should definitely work: isEmptyRenaming (_, tv_subst, co_subst) = all isTyVarTy (varEnvElts tv_subst) && all isCoVarCo (varEnvElts co_subst) _______________________________________________ Cvs-ghc mailing list Cvs-ghc@haskell.org http://www.haskell.org/mailman/listinfo/cvs-ghc
