Commit 5df7a7ab authored by afarmer's avatar afarmer Committed by Ben Gamari
Browse files

Don't inline/apply other rules when simplifying a rule RHS.

HERMIT users depend on RULES to specify equational properties. 6.10.2
performed both inlining and simplification in both sides of the rules,
meaning they can't really be used for this. This breaks most HERMIT use
cases.  A separate commit already disabled this for the LHS of rules.
This does so for the RHS.

See Trac #10829 for nofib results.

Reviewed By: austin, bgamari, simonpj

Differential Revision: https://phabricator.haskell.org/D1246

GHC Trac Issues: #10829
parent 2f8f79bd
......@@ -14,7 +14,7 @@ module SimplUtils (
preInlineUnconditionally, postInlineUnconditionally,
activeUnfolding, activeRule,
getUnfoldingInRuleMatch,
simplEnvForGHCi, updModeForStableUnfoldings, updModeForRuleLHS,
simplEnvForGHCi, updModeForStableUnfoldings, updModeForRules,
-- The continuation type
SimplCont(..), DupFlag(..),
......@@ -700,20 +700,25 @@ updModeForStableUnfoldings inline_rule_act current_mode
phaseFromActivation (ActiveAfter n) = Phase n
phaseFromActivation _ = InitialPhase
updModeForRuleLHS :: SimplifierMode -> SimplifierMode
-- See Note [Simplifying RULE LHSs]
updModeForRuleLHS current_mode
updModeForRules :: SimplifierMode -> SimplifierMode
-- See Note [Simplifying rules]
updModeForRules current_mode
= current_mode { sm_phase = InitialPhase
, sm_inline = False
, sm_rules = False
, sm_eta_expand = False }
{- Note [Simplifying RULE LHSs]
{- Note [Simplifying rules]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When simplifying on the LHS of a rule, refrain from all inlining and
all RULES. Doing anything to the LHS is plain confusing, because it
means that what the rule matches is not what the user wrote.
c.f. Trac #10595, and #10528.
When simplifying a rule, refrain from any inlining or applying of other RULES.
Doing anything to the LHS is plain confusing, because it means that what the
rule matches is not what the user wrote. c.f. Trac #10595, and #10528.
Moreover, inlining (or applying rules) on rule LHSs risks introducing
Ticks into the LHS, which makes matching trickier. Trac #10665, #10745.
Doing this to either side confounds tools like HERMIT, which seek to reason
about and apply the RULES as originally written. See Trac #10829.
Note [Inlining in gentle mode]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
......
......@@ -2966,13 +2966,11 @@ simplRules env mb_new_nm rules
= return rule
simpl_rule rule@(Rule { ru_bndrs = bndrs, ru_args = args
, ru_fn = fn_name, ru_rhs = rhs
, ru_act = act })
= do { (env, bndrs') <- simplBinders env bndrs
; let lhs_env = updMode updModeForRuleLHS env
rhs_env = updMode (updModeForStableUnfoldings act) env
; args' <- mapM (simplExpr lhs_env) args
; rhs' <- simplExpr rhs_env rhs
, ru_fn = fn_name, ru_rhs = rhs })
= do { (env', bndrs') <- simplBinders env bndrs
; let rule_env = updMode updModeForRules env'
; args' <- mapM (simplExpr rule_env) args
; rhs' <- simplExpr rule_env rhs
; return (rule { ru_bndrs = bndrs'
, ru_fn = mb_new_nm `orElse` fn_name
, ru_args = args'
......
......@@ -4,7 +4,5 @@
forall ($dMyFunctor :: MyFunctor []) (irred :: Domain [] Int).
shared @ [] $dMyFunctor irred
= bar_$sshared
"SPEC/Foo myfmap @ []" [ALWAYS]
forall (tpl :: MyFunctor []). myfmap @ [] tpl = $cmyfmap
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