From 37b8fd8cf56292765b6749bc7b088fa7fd1565c8 Mon Sep 17 00:00:00 2001
From: Joe Wilm <joe@jwilm.com>
Date: Sat, 19 May 2018 15:58:49 -0700
Subject: [PATCH] Remove checking on remainder op

The length of the underlying storage will *never* be zero.

This removes generated code that branches on the possibility that len is
zero.
---
 src/grid/storage.rs | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/grid/storage.rs b/src/grid/storage.rs
index d517fa01..9a56872e 100644
--- a/src/grid/storage.rs
+++ b/src/grid/storage.rs
@@ -174,6 +174,14 @@ impl<T> Storage<T> {
 
     /// Compute actual index in underlying storage given the requested index.
     fn compute_index(&self, requested: usize) -> usize {
+        use ::std::hint::unreachable_unchecked;
+
+        // This prevents an extra branch being inserted which checks for the
+        // divisor to be zero thus making a % b generate equivalent code as in C
+        if self.inner.len() == 0 {
+            unsafe { unreachable_unchecked(); }
+        }
+
         (requested + self.zero) % self.inner.len()
     }