2441bf1f76
This PR makes `simp` consult its own cache more often, to avoid replicating work. Before, the simp cache was checked upon entry of `simpImpl` only, which then calls `simpLoop`, which recursively iterates the `pre`-lemmas, without checking the cache again. Now, `simpLoop` itself checks the cache. This seems more principled, given that `simpLoop` is actually putting entries into the cache for each of its calls, so it’s more uniform if it checks the cache itself. This avoids repeated rewrites. For example given ``` theorem ab : a = b := testSorry theorem bc : b = c := testSorry example (h : P c) : P b ∧ P a := by simp [ab, bc, h] ``` simp would rewrite `b ==> c` twice (once as part of `b ==> c` and then again as part of `a ==> b ==> c`). And it’d be order dependent: With ``` example (h : P c) : P a ∧ P b := by simp [ab, bc, h] ``` the `a ==> b ==> c` chain would insert `b ==> c` into the cache, and picked up by `simpImpl` when rewriting `P b`. With this change, `b ==> c` is performed only once in both examples. Instruction counts on stdlib and mathlib both show a mild improvement across the board (0.5%), with individual modules improving by up to 4% in stdlib and even more in mathlib. (This does not check the cache before applying `post`, which explains where there are still some repeated rewrites in the trace logs. But I’m less sure about inserting a cache check here and so I am treading carefully here. It’s also going to be at most one `post` application that’s duplicated, because if `post` returns `.visit`, we go back to `pre` and thus a cache check.)
33 lines
1.1 KiB
Text
33 lines
1.1 KiB
Text
def ack : Nat → Nat → Nat
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| 0, y => y+1
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| x+1, 0 => ack x 1
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| x+1, y+1 => ack x (ack (x+1) y)
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termination_by a b => (a, b)
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/--
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trace: [diag] Diagnostics
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[kernel] unfolded declarations (max: 147, num: 3):
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[kernel] OfNat.ofNat ↦ 147
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[kernel] Add.add ↦ 61
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[kernel] HAdd.hAdd ↦ 61
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use `set_option diagnostics.threshold <num>` to control threshold for reporting counters
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---
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trace: [simp] Diagnostics
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[simp] used theorems (max: 57, num: 1):
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[simp] ack.eq_3 ↦ 57
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[simp] tried theorems (max: 57, num: 1):
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[simp] ack.eq_3 ↦ 57, succeeded: 57
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use `set_option diagnostics.threshold <num>` to control threshold for reporting counters
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---
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trace: [diag] Diagnostics
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[kernel] unfolded declarations (max: 147, num: 3):
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[kernel] OfNat.ofNat ↦ 147
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[kernel] Add.add ↦ 61
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[kernel] HAdd.hAdd ↦ 61
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use `set_option diagnostics.threshold <num>` to control threshold for reporting counters
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-/
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#guard_msgs in
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set_option diagnostics.threshold 50 in
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set_option diagnostics true in
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theorem ex : ack 3 2 = 29 :=
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by simp [ack]
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