37b53b70d0
This PR improves bv_decide's performance in the presence of large
literals.
The core change of this PR is the reformulation of the reflection code
for literals to:
```diff
def eval (assign : Assignment) : BVExpr w → BitVec w
| .var idx =>
- let ⟨bv⟩ := assign.get idx
- bv.truncate w
+ let packedBv := assign.get idx
+ /-
+ This formulation improves performance, as in a well formed expression the condition always holds
+ so there is no need for the more involved `BitVec.truncate` logic.
+ -/
+ if h : packedBv.w = w then
+ h ▸ packedBv.bv
+ else
+ packedBv.bv.truncate w
```
The remainder is merely further simplifications that make the terms
smaller and easier to deal with in general. This change is motivated by
applying the following diff to the kernel:
```diff
diff --git a/src/kernel/type_checker.cpp b/src/kernel/type_checker.cpp
index b0e6844dca..f13bb96bd4 100644
--- a/src/kernel/type_checker.cpp
+++ b/src/kernel/type_checker.cpp
@@ -518,6 +518,7 @@ optional<constant_info> type_checker::is_delta(expr const & e) const {
optional<expr> type_checker::unfold_definition_core(expr const & e) {
if (is_constant(e)) {
if (auto d = is_delta(e)) {
+// std::cout << "Working on unfolding: " << d->get_name() << std::endl;
if (length(const_levels(e)) == d->get_num_lparams()) {
if (m_diag) {
m_diag->record_unfold(d->get_name());
```
and observing that in the test case from #6043 we see a long series of
```
Working on unfolding: Bool.decEq
Working on unfolding: Bool.decEq.match_1
Working on unfolding: Bool.casesOn
Working on unfolding: Nat.ble
Working on unfolding: Nat.brecOn
Working on unfolding: Nat.beq.match_1
Working on unfolding: Nat.casesOn
Working on unfolding: Nat.casesOn
Working on unfolding: Nat.beq.match_1
Working on unfolding: Nat.casesOn
Working on unfolding: Nat.casesOn
```
the chain begins with `BitVec.truncate`, works through a few
abstractions and then continues like above forever, so I avoid the call
to truncate like this. It is not quite clear to me why removing `ofBool`
helps so much here, maybe some other kernel heuristic kicks in to rescue
us.
Either way this diff is a general improvement for reflection of `BitVec`
constants as we should never have to run `BitVec.truncate` again!
Fixes: #6043
105 lines
4.8 KiB
Text
105 lines
4.8 KiB
Text
import Std.Tactic.BVDecide
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theorem x_eq_y (x y : Bool) (hx : x = True) (hy : y = True) : x = y := by
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bv_decide
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example (z : BitVec 64) : True := by
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let x : BitVec 64 := 10
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let y : BitVec 64 := 20 + z
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have : z + (2 * x) = y := by
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bv_decide
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exact True.intro
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example :
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¬ (0 ≤ 0 + 16#64 ∧ 0 ≤ 0 + 16#64 ∧ (0 + 16#64 ≤ 0 ∨ 0 ≥ 0 + 16#64 ∨ 16#64 = 0 ∨ 16#64 = 0)) := by
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bv_normalize
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example (x y z : BitVec 8) (h1 : x = z → False) (h2 : x = y) (h3 : y = z) : False := by
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bv_decide
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def mem_subset (a1 a2 b1 b2 : BitVec 64) : Bool :=
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(b2 - b1 = BitVec.ofNat 64 (2^64 - 1)) ||
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((a2 - b1 <= b2 - b1 && a1 - b1 <= a2 - b1))
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-- Show that bv_normalize yields the preprocessed goal
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theorem mem_subset_refl : mem_subset a1 a2 a1 a2 := by
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unfold mem_subset
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bv_normalize
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sorry
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example {x : BitVec 16} : 0#16 + x = x := by bv_normalize
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example {x : BitVec 16} : x + 0#16 = x := by bv_normalize
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example {x : BitVec 16} : x.setWidth 16 = x := by bv_normalize
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example : (0#w).setWidth 32 = 0#32 := by bv_normalize
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example : (0#w).getLsbD i = false := by bv_normalize
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example {x : BitVec 0} : x.getLsbD i = false := by bv_normalize
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example {x : BitVec 16} {b : Bool} : (x.concat b).getLsbD 0 = b := by bv_normalize
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example {x : BitVec 16} : 1 * x = x := by bv_normalize
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example {x : BitVec 16} : x * 1 = x := by bv_normalize
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example {x : BitVec 16} : ~~~(~~~x) = x := by bv_normalize
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example {x : BitVec 16} : x &&& 0 = 0 := by bv_normalize
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example {x : BitVec 16} : 0 &&& x = 0 := by bv_normalize
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example {x : BitVec 16} : (-1#16) &&& x = x := by bv_normalize
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example {x : BitVec 16} : x &&& (-1#16) = x := by bv_normalize
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example {x : BitVec 16} : x &&& x = x := by bv_normalize
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example {x : BitVec 16} : x &&& ~~~x = 0 := by bv_normalize
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example {x : BitVec 16} : ~~~x &&& x = 0 := by bv_normalize
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example {x : BitVec 16} : x + ~~~x = -1 := by bv_normalize
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example {x : BitVec 16} : ~~~x + x = -1 := by bv_normalize
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example {x : BitVec 16} : x + (-x) = 0 := by bv_normalize
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example {x : BitVec 16} : (-x) + x = 0 := by bv_normalize
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example {x : BitVec 16} : x + x = x * 2 := by bv_normalize
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example : BitVec.sshiftRight 0#16 n = 0#16 := by bv_normalize
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example {x : BitVec 16} : BitVec.sshiftRight x 0 = x := by bv_normalize
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example {x : BitVec 16} : 0#16 * x = 0 := by bv_normalize
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example {x : BitVec 16} : x * 0#16 = 0 := by bv_normalize
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example {x : BitVec 16} : x <<< 0#16 = x := by bv_normalize
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example {x : BitVec 16} : x <<< 0 = x := by bv_normalize
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example : 0#16 <<< (n : Nat) = 0 := by bv_normalize
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example : 0#16 >>> (n : Nat) = 0 := by bv_normalize
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example {x : BitVec 16} : x >>> 0#16 = x := by bv_normalize
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example {x : BitVec 16} : x >>> 0 = x := by bv_normalize
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example {x : BitVec 16} : 0 < x ↔ (x != 0) := by bv_normalize
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example {x : BitVec 16} : ¬(-1#16 < x) := by bv_normalize
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example {x : BitVec 16} : BitVec.replicate 0 x = 0 := by bv_normalize
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example : BitVec.ofBool true = 1 := by bv_normalize
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example : BitVec.ofBool false = 0 := by bv_normalize
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example {x : BitVec 16} {i} {h} : x[i] = x.getLsbD i := by bv_normalize
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example {x y : BitVec 1} : x + y = x ^^^ y := by bv_normalize
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example {x y : BitVec 1} : x * y = x &&& y := by bv_normalize
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example {x : BitVec 16} : x / 0 = 0 := by bv_normalize
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example {x : BitVec 16} : x % 0 = x := by bv_normalize
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example {x : BitVec 16} : ~~~(-x) = x + (-1#16) := by bv_normalize
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example {x : BitVec 16} : ~~~(~~~x + 1#16) = x + (-1#16) := by bv_normalize
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example {x : BitVec 16} : ~~~(x + 1#16) = ~~~x + (-1#16) := by bv_normalize
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example {x : BitVec 16} : ~~~(1#16 + ~~~x) = x + (-1#16) := by bv_normalize
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example {x : BitVec 16} : ~~~(1#16 + x) = ~~~x + (-1#16) := by bv_normalize
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example {x : BitVec 16} : (10 + x) + 2 = 12 + x := by bv_normalize
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example {x : BitVec 16} : (x + 10) + 2 = 12 + x := by bv_normalize
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example {x : BitVec 16} : 2 + (x + 10) = 12 + x := by bv_normalize
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example {x : BitVec 16} : 2 + (10 + x) = 12 + x := by bv_normalize
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example {x : BitVec 16} {b : Bool} : (if b then x else x) = x := by bv_normalize
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example {b : Bool} {x : Bool} : (bif b then x else x) = x := by bv_normalize
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example {x : BitVec 16} : x.abs = if x.msb then -x else x := by bv_normalize
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example : (BitVec.twoPow 16 2) = 4#16 := by bv_normalize
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example {x : BitVec 16} : x / (BitVec.twoPow 16 2) = x >>> 2 := by bv_normalize
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example {x : BitVec 16} : x / (BitVec.ofNat 16 8) = x >>> 3 := by bv_normalize
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example {x y : Bool} (h1 : x && y) : x || y := by bv_normalize
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example (a b c: Bool) : (if a then b else c) = (if !a then c else b) := by bv_normalize
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section
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example (x y : BitVec 256) : x * y = y * x := by
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bv_decide (config := { acNf := true })
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example {x y z : BitVec 64} : ~~~(x &&& (y * z)) = (~~~x ||| ~~~(z * y)) := by
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bv_decide (config := { acNf := true })
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end
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def foo (x : Bool) : Prop := x = true
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example (x : Bool) (h1 h2 : x = true) : foo x := by
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bv_normalize
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have : x = true := by assumption
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sorry
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