perf: add high priority to OfSemiring.Q instances

This PR adds high priority to instances for `OfSemiring.Q` in the grind
ring envelope. When Mathlib is imported, instance synthesis for types like
`OfSemiring.Q Nat` becomes very expensive because the solver explores many
irrelevant paths before finding the correct instances. By marking these
instances as high priority and adding shortcut instances for basic operations
(Add, Sub, Mul, Neg, OfNat, NatCast, IntCast, HPow), instance synthesis
resolves quickly.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
This commit is contained in:
Leonardo de Moura
2026-03-03 18:28:16 -08:00
parent cda84702e9
commit 209af53427

View File

@@ -330,7 +330,7 @@ theorem toQ_inj [AddRightCancel α] {a b : α} : toQ a = toQ b → a = b := by
obtain k, h₁ := h₁
exact AddRightCancel.add_right_cancel a b k h₁
instance [Semiring α] [AddRightCancel α] [NoNatZeroDivisors α] : NoNatZeroDivisors (OfSemiring.Q α) where
instance (priority := high) [Semiring α] [AddRightCancel α] [NoNatZeroDivisors α] : NoNatZeroDivisors (OfSemiring.Q α) where
no_nat_zero_divisors := by
intro k a b h₁ h₂
replace h₂ : mul (natCast k) a = mul (natCast k) b := h₂
@@ -346,7 +346,7 @@ instance [Semiring α] [AddRightCancel α] [NoNatZeroDivisors α] : NoNatZeroDiv
replace h₂ := NoNatZeroDivisors.no_nat_zero_divisors k (a₁ + b₂) (a₂ + b₁) h₁ h₂
apply Quot.sound; simp [r]; exists 0; simp [h₂]
instance {p} [Semiring α] [AddRightCancel α] [IsCharP α p] : IsCharP (OfSemiring.Q α) p where
instance (priority := high) {p} [Semiring α] [AddRightCancel α] [IsCharP α p] : IsCharP (OfSemiring.Q α) p where
ofNat_ext_iff := by
intro x y
constructor
@@ -366,7 +366,7 @@ instance {p} [Semiring α] [AddRightCancel α] [IsCharP α p] : IsCharP (OfSemir
apply Quot.sound
exists 0; simp [ Semiring.ofNat_eq_natCast, this]
instance [LE α] [IsPreorder α] [OrderedAdd α] : LE (OfSemiring.Q α) where
instance (priority := high) [LE α] [IsPreorder α] [OrderedAdd α] : LE (OfSemiring.Q α) where
le a b := Q.liftOn₂ a b (fun (a, b) (c, d) => a + d b + c)
(by intro (a₁, b₁) (a₂, b₂) (a₃, b₃) (a₄, b₄)
simp; intro k₁ h₁ k₂ h₂
@@ -382,14 +382,14 @@ instance [LE α] [IsPreorder α] [OrderedAdd α] : LE (OfSemiring.Q α) where
rw [this]; clear this
rw [ OrderedAdd.add_le_left_iff])
instance [LE α] [IsPreorder α] [OrderedAdd α] : LT (OfSemiring.Q α) where
instance (priority := high) [LE α] [IsPreorder α] [OrderedAdd α] : LT (OfSemiring.Q α) where
lt a b := a b ¬b a
@[local simp] theorem mk_le_mk [LE α] [IsPreorder α] [OrderedAdd α] {a₁ a₂ b₁ b₂ : α} :
Q.mk (a₁, a₂) Q.mk (b₁, b₂) a₁ + b₂ a₂ + b₁ := by
rfl
instance [LE α] [IsPreorder α] [OrderedAdd α] : IsPreorder (OfSemiring.Q α) where
instance (priority := high) [LE α] [IsPreorder α] [OrderedAdd α] : IsPreorder (OfSemiring.Q α) where
le_refl a := by
obtain a₁, a₂ := a
change Q.mk _ Q.mk _
@@ -424,7 +424,7 @@ theorem toQ_le [LE α] [IsPreorder α] [OrderedAdd α] {a b : α} : toQ a ≤ to
theorem toQ_lt [LE α] [LT α] [LawfulOrderLT α] [IsPreorder α] [OrderedAdd α] {a b : α} : toQ a < toQ b a < b := by
simp [lt_iff_le_and_not_ge]
instance [LE α] [IsPreorder α] [OrderedAdd α] : OrderedAdd (OfSemiring.Q α) where
instance (priority := high) [LE α] [IsPreorder α] [OrderedAdd α] : OrderedAdd (OfSemiring.Q α) where
add_le_left_iff := by
intro a b c
obtain a₁, a₂ := a
@@ -438,7 +438,7 @@ instance [LE α] [IsPreorder α] [OrderedAdd α] : OrderedAdd (OfSemiring.Q α)
rw [ OrderedAdd.add_le_left_iff]
-- This perhaps works in more generality than `ExistsAddOfLT`?
instance [LE α] [LT α] [LawfulOrderLT α] [IsPreorder α] [OrderedRing α] [ExistsAddOfLT α] : OrderedRing (OfSemiring.Q α) where
instance (priority := high) [LE α] [LT α] [LawfulOrderLT α] [IsPreorder α] [OrderedRing α] [ExistsAddOfLT α] : OrderedRing (OfSemiring.Q α) where
zero_lt_one := by
rw [ toQ_ofNat, toQ_ofNat, toQ_lt]
exact OrderedRing.zero_lt_one
@@ -511,7 +511,16 @@ def ofCommSemiring : CommRing (OfSemiring.Q α) :=
{ OfSemiring.ofSemiring with
mul_comm := mul_comm }
attribute [instance] ofCommSemiring
attribute [instance high] ofCommSemiring
instance (priority := high) [CommRing (OfSemiring.Q α)] : Add (OfSemiring.Q α) := by infer_instance
instance (priority := high) [CommRing (OfSemiring.Q α)] : Sub (OfSemiring.Q α) := by infer_instance
instance (priority := high) [CommRing (OfSemiring.Q α)] : Mul (OfSemiring.Q α) := by infer_instance
instance (priority := high) [CommRing (OfSemiring.Q α)] : Neg (OfSemiring.Q α) := by infer_instance
instance (priority := high) [CommRing (OfSemiring.Q α)] : OfNat (OfSemiring.Q α) n := by infer_instance
attribute [local instance] Semiring.natCast Ring.intCast
instance (priority := high) [CommRing (OfSemiring.Q α)] : NatCast (OfSemiring.Q α) := by infer_instance
instance (priority := high) [CommRing (OfSemiring.Q α)] : IntCast (OfSemiring.Q α) := by infer_instance
instance (priority := high) [CommRing (OfSemiring.Q α)] : HPow (OfSemiring.Q α) Nat (OfSemiring.Q α) := by infer_instance
/-
Remark: `↑a` is notation for `OfSemiring.toQ a`.