96e7ab078d
This PR fixes a performance issue that occurs when generating equation lemmas for functions that use match-expressions containing several literals. This issue was exposed by #9322 and arises from a combination of factors: 1. Literal values are compiled into a chain of dependent if-then-else expressions. 2. Dependent if-then-else expressions are significantly more expensive to simplify than regular ones. 3. The `split` tactic selects a target, splits it, and then invokes `simp` on the resulting subgoals. Moreover, `simp` traverses the entire goal bottom-up and does not stop after reaching the target. This PR addresses the issue by introducing a custom simproc that avoids recursively simplifying nested if-then-else expressions. It does **not** alter the user-facing behavior of the `split` tactic because such a change would be highly disruptive. Instead, the PR adds a new flag, `backward.split` to control the behavior of the user-facing `split` tactic. It is currently set to `true`, i.e., the old behavior is still the default one. In a future PR, we should set this flag to `false` by default and begin repairing all affected proofs. closes #9322
56 lines
1.2 KiB
Text
56 lines
1.2 KiB
Text
structure CompoundName where
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module : String
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name : String
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structure T where
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name : CompoundName
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placeholder : Nat
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/--
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Value whose size is bounded by a constant offset of another value.
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-/
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abbrev Bounded (α : Type _) [SizeOf α] {β} [SizeOf β] (e : β) (c : Int) := { a : α // sizeOf a ≤ sizeOf e + c }
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def getArg (e : T) : Bounded T e (-1) := sorry
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mutual
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inductive A where
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| a : A
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| b : C → A
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inductive C
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| c : A → C
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end
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mutual
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def mkA (x : T) : A :=
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match x.name with
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| CompoundName.mk "LongName" "a" => .a
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| CompoundName.mk "LongName" "b" => .a
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| CompoundName.mk "LongName" "c" => .a
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| CompoundName.mk "LongName" "d" => .a
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| CompoundName.mk "LongName" "e" => .a
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| CompoundName.mk "LongName" "f" => .a
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| CompoundName.mk "LongName" "g" => .a
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| CompoundName.mk "LongName" "h" => .a
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| CompoundName.mk "LongName" "i" => .a
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| CompoundName.mk "LongName" "j" => .a
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| CompoundName.mk "LongName" "k" => .a
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| CompoundName.mk "LongName" "z" =>
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let ⟨y, _⟩ := getArg x
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.b (mkC y)
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| _ => sorry
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termination_by sizeOf x
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def mkC (x : T) : C :=
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match x.name with
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| CompoundName.mk "LongName" "b" =>
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let ⟨y, _⟩ := getArg x
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.c (mkA y)
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| f => sorry
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termination_by sizeOf x
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end
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