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fix: unnecessary NatModules in grind linarith (#10326)

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This PR fixes a performance issue in `grind linarith`. It was creating
unnecessary `NatModule`/`IntModule` structures for commutative rings
without an order. This kind of type should be handled by `grind ring`
only.
This commit is contained in:
Leonardo de Moura 2025-09-09 20:51:51 -07:00 • committed by GitHub
parent bb61a2d481
commit fc6a6cc4e2
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2 changed files with 17 additions and 2 deletions
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13
src/Lean/Meta/Tactic/Grind/Arith/Linear/StructId.lean
View file

@ -214,8 +214,14 @@ where
let isPartialInst? ← mkIsPartialOrderInst? u type leInst?
let isLinearInst? ← mkIsLinearOrderInst? u type leInst?
if (← getConfig).ring && ringId?.isSome && isPreorderInst?.isNone then
-- If `type` is a `CommRing`, but it is not even a preorder, there is no point in use this module.
-- `ring` module should handle it.
/-
If the type is a `Ring` **and** is not even a preorder **and** `grind ring` is enabled,
we let `grind ring` process the equalities and disequalities. There is no
point in using `linarith` in this case.
**IMPORTANT** We mark the type as a "forbiddenNatModule". It would be pointless to recheck everything in
in `getNatStructId?`
-/
modify' fun s => { s with forbiddenNatModules := s.forbiddenNatModules.insert { expr := type } }
return none
let commRingInst? ← getCommRingInst? ringId?
let ringInst? ← mkRingInst? u type commRingInst?
@ -229,6 +235,8 @@ where
let isPreorderInst? := if orderedAddInst?.isNone then none else isPreorderInst?
-- preorderInst? may have been reset, check again whether this module is needed.
if (← getConfig).ring && ringId?.isSome && isPreorderInst?.isNone then
-- See comment above
modify' fun s => { s with forbiddenNatModules := s.forbiddenNatModules.insert { expr := type } }
return none
let isPartialInst? ← checkToFieldDefEq? leInst? isPreorderInst? isPartialInst? ``Std.IsPartialOrder.toIsPreorder u type
let isLinearInst? ← checkToFieldDefEq? leInst? isPartialInst? isLinearInst? ``Std.IsLinearOrder.toIsPartialOrder u type
@ -303,6 +311,7 @@ private def mkNatModuleInst? (u : Level) (type : Expr) : GoalM (Option Expr) :=
def getNatStructId? (type : Expr) : GoalM (Option Nat) := do
unless (← getConfig).linarith do return none
if (← get').forbiddenNatModules.contains { expr := type } then return none
if (← isCutsatType type) then return none
if let some id? := (← get').natTypeIdOf.find? { expr := type } then
return id?

6
src/Lean/Meta/Tactic/Grind/Arith/Linear/Types.lean
View file

@ -247,6 +247,12 @@ structure State where
typeIdOf : PHashMap ExprPtr (Option Nat) := {}
/- Mapping from expressions/terms to their structure ids. -/
exprToStructId : PHashMap ExprPtr Nat := {}
/--
Some types are unordered rings, so we do not process them in `linarith`.
When such types are detected in `getStructId?`, we add them to the set
`forbiddenNatModules` to avoid reprocessing them in `getNatStructId?`.
-/
forbiddenNatModules : PHashSet ExprPtr := {}
/-- `NatModule`. We support them using the envelope `OfNatModule.Q` -/
natStructs : Array NatStruct := {}
/--