From 574e510ba069f1747ecb1e5a17cf86c902d79d44 Mon Sep 17 00:00:00 2001
From: Pierre-Marie Pédrot
Date: Thu, 19 Nov 2015 18:40:32 +0100
Subject: Fix bug #4429: eauto with arith: 70x performance regression in Coq
 8.5.

The issue was due to the fact that unfold hints are given a priority of 4
by default. As eauto was now using hint priority rather than the number of
goals produced to order the application of hints, unfold were almost always
used too late. We fixed this by manually giving them a priority of 1 in the
eauto tactic.

Also fixed the relative order of proof depth w.r.t. hint priority. It should not
be observable except for breadth-first search, which is seldom used.
---
 test-suite/bugs/closed/4429.v | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)
 create mode 100644 test-suite/bugs/closed/4429.v

(limited to 'test-suite/bugs')

diff --git a/test-suite/bugs/closed/4429.v b/test-suite/bugs/closed/4429.v
new file mode 100644
index 0000000000..bf0e570ab8
--- /dev/null
+++ b/test-suite/bugs/closed/4429.v
@@ -0,0 +1,31 @@
+Require Import Arith.Compare_dec.
+Require Import Unicode.Utf8.
+
+Fixpoint my_nat_iter (n : nat) {A} (f : A → A) (x : A) : A :=
+  match n with
+    | O    => x
+    | S n' => f (my_nat_iter n' f x)
+  end.
+
+Definition gcd_IT_F (f : nat * nat → nat) (mn : nat * nat) : nat :=
+  match mn with
+    | (0, 0)       => 0
+    | (0, S n')    => S n'
+    | (S m', 0)    => S m'
+    | (S m', S n') =>
+      match le_gt_dec (S m') (S n') with
+        | left  _ => f (S m', S n' - S m')
+        | right _ => f (S m' - S n', S n')
+      end
+  end.
+
+Axiom max_correct_l : ∀ m n : nat, m <= max m n.
+Axiom max_correct_r : ∀ m n : nat, n <= max m n.
+
+Hint Resolve max_correct_l max_correct_r : arith.
+
+Theorem foo : ∀ p p' p'' : nat, p'' < S (max p (max p' p'')).
+Proof.
+  intros.
+  Timeout 3 eauto with arith.
+Qed.
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