From 336a1f906a9c617e68e9d43e244bf42e9bdbae64 Mon Sep 17 00:00:00 2001
From: xleroy <xleroy@fca1b0fc-160b-0410-b1d3-a4f43f01ea2e>
Date: Wed, 9 Apr 2014 13:26:16 +0000
Subject: Constprop: use "not" for "xorimm(-1)"; optimize == 1 and != 0
 comparisons over booleans. Select*: more systematic constant propagation;
 don't CP shifts by amounts outside of [0..31]. Driver: timer for whole
 compilation.

git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2452 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
---
 lib/Integers.v | 10 ++++++++++
 1 file changed, 10 insertions(+)

(limited to 'lib')

diff --git a/lib/Integers.v b/lib/Integers.v
index d85007b..4464d26 100644
--- a/lib/Integers.v
+++ b/lib/Integers.v
@@ -1202,6 +1202,11 @@ Qed.
 Remark Ztestbit_0: forall n, Z.testbit 0 n = false.
 Proof Z.testbit_0_l.
 
+Remark Ztestbit_1: forall n, Z.testbit 1 n = zeq n 0.
+Proof.
+  intros. destruct n; simpl; auto.
+Qed.
+
 Remark Ztestbit_m1: forall n, 0 <= n -> Z.testbit (-1) n = true.
 Proof.
   intros. destruct n; simpl; auto. 
@@ -1515,6 +1520,11 @@ Proof.
   intros. unfold testbit. rewrite unsigned_zero. apply Ztestbit_0. 
 Qed.
 
+Remark bits_one: forall n, testbit one n = zeq n 0.
+Proof.
+  unfold testbit; intros. rewrite unsigned_one. apply Ztestbit_1. 
+Qed.
+
 Lemma bits_mone:
   forall i, 0 <= i < zwordsize -> testbit mone i = true.
 Proof.
-- 
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