diff options
Diffstat (limited to 'compiler')
| -rw-r--r-- | compiler/simplCore/CSE.hs | 1 | ||||
| -rw-r--r-- | compiler/simplCore/OccurAnal.hs | 7 | ||||
| -rw-r--r-- | compiler/simplCore/SimplCore.hs | 8 |
3 files changed, 12 insertions, 4 deletions
diff --git a/compiler/simplCore/CSE.hs b/compiler/simplCore/CSE.hs index 9a0945e290..0835f87bb0 100644 --- a/compiler/simplCore/CSE.hs +++ b/compiler/simplCore/CSE.hs @@ -327,6 +327,7 @@ the program; it's a kind of synthetic key for recursive bindings. ************************************************************************ -} +-- | Requires bindings to be in dependency order. cseProgram :: CoreProgram -> CoreProgram cseProgram binds = snd (mapAccumL (cseBind TopLevel) emptyCSEnv binds) diff --git a/compiler/simplCore/OccurAnal.hs b/compiler/simplCore/OccurAnal.hs index 96ee9623c3..47460178f1 100644 --- a/compiler/simplCore/OccurAnal.hs +++ b/compiler/simplCore/OccurAnal.hs @@ -81,11 +81,16 @@ occurAnalysePgm this_mod active_unf active_rule imp_rules binds (final_usage, occ_anald_binds) = go init_env binds (_, occ_anald_glommed_binds) = occAnalRecBind init_env TopLevel imp_rule_edges - (flattenBinds occ_anald_binds) + (flattenBinds binds) initial_uds -- It's crucial to re-analyse the glommed-together bindings -- so that we establish the right loop breakers. Otherwise -- we can easily create an infinite loop (#9583 is an example) + -- + -- Also crucial to re-analyse the /original/ bindings + -- in case the first pass accidentally discarded as dead code + -- a binding that was actually needed (albeit before its + -- definition site). #17724 threw this up. initial_uds = addManyOccsSet emptyDetails (rulesFreeVars imp_rules) diff --git a/compiler/simplCore/SimplCore.hs b/compiler/simplCore/SimplCore.hs index b8fb162432..799dfa93fe 100644 --- a/compiler/simplCore/SimplCore.hs +++ b/compiler/simplCore/SimplCore.hs @@ -318,15 +318,17 @@ getCoreToDo dflags maybe_rule_check (Phase 0), - runWhen late_specialise - (CoreDoPasses [ CoreDoSpecialising - , simpl_phase 0 ["post-late-spec"] max_iter]), + runWhen late_specialise CoreDoSpecialising, -- LiberateCase can yield new CSE opportunities because it peels -- off one layer of a recursive function (concretely, I saw this -- in wheel-sieve1), and I'm guessing that SpecConstr can too -- And CSE is a very cheap pass. So it seems worth doing here. + -- This helps shake out any effect of liberate_case/spec_constr. + -- It also puts bindings in dependency order, which helps with CSE. runWhen ((liberate_case || spec_constr) && cse) CoreCSE, + ( CoreDoPasses [ simpl_phase 0 ["pre-late-cse"] max_iter + , CoreCSE ]), -- Final clean-up simplification: simpl_phase 0 ["final"] max_iter, |