From 25d9f3f6cab38a5df86fcfb059a75249f371aa15 Mon Sep 17 00:00:00 2001
From: Henry de Valence <hdevalence@hdevalence.ca>
Date: Wed, 13 Jun 2018 16:41:57 -0700
Subject: [PATCH] Eliminate vector constants from `edwards` module

---
 src/backend/avx2/constants.rs | 18 ++++++++++++++++++
 src/backend/avx2/edwards.rs   | 21 +++------------------
 src/backend/avx2/field.rs     |  2 --
 3 files changed, 21 insertions(+), 20 deletions(-)

diff --git a/src/backend/avx2/constants.rs b/src/backend/avx2/constants.rs
index e99e312..f08daa7 100644
--- a/src/backend/avx2/constants.rs
+++ b/src/backend/avx2/constants.rs
@@ -16,6 +16,24 @@ use backend::avx2::edwards::{CachedPoint, ExtendedPoint};
 use backend::avx2::field::FieldElement32x4;
 use scalar_mul::window::NafLookupTable8;
 
+/// The identity element as an `ExtendedPoint`.
+pub(crate) static EXTENDEDPOINT_IDENTITY: ExtendedPoint = ExtendedPoint(FieldElement32x4([
+    u32x8::new(0, 1, 0, 0, 1, 0, 0, 0),
+    u32x8::splat(0),
+    u32x8::splat(0),
+    u32x8::splat(0),
+    u32x8::splat(0),
+]));
+
+/// The identity element as a `CachedPoint`.
+pub(crate) static CACHEDPOINT_IDENTITY: CachedPoint = CachedPoint(FieldElement32x4([
+    u32x8::new(121647, 121666, 0, 0, 243332, 67108845, 0, 33554431),
+    u32x8::new(67108864, 0, 33554431, 0, 0, 67108863, 0, 33554431),
+    u32x8::new(67108863, 0, 33554431, 0, 0, 67108863, 0, 33554431),
+    u32x8::new(67108863, 0, 33554431, 0, 0, 67108863, 0, 33554431),
+    u32x8::new(67108863, 0, 33554431, 0, 0, 67108863, 0, 33554431),
+]));
+
 /// The low limbs of (2p, 2p, 2p, 2p), so that
 /// ```no_run
 /// (2p, 2p, 2p, 2p) = [P_TIMES_2_LO, P_TIMES_2_HI, P_TIMES_2_HI, P_TIMES_2_HI, P_TIMES_2_HI]
diff --git a/src/backend/avx2/edwards.rs b/src/backend/avx2/edwards.rs
index 1c7c616..a04c785 100644
--- a/src/backend/avx2/edwards.rs
+++ b/src/backend/avx2/edwards.rs
@@ -16,8 +16,6 @@
 use core::convert::From;
 use core::ops::{Add, Neg, Sub};
 
-use core::simd::{u32x8, IntoBits};
-
 use subtle::Choice;
 use subtle::ConditionallyAssignable;
 
@@ -27,8 +25,7 @@ use scalar_mul::window::{LookupTable, NafLookupTable5, NafLookupTable8};
 use traits::Identity;
 
 use backend::avx2::field::{FieldElement32x4, Lanes, Shuffle};
-
-use backend::avx2;
+use backend::avx2::constants;
 
 /// A point on Curve25519, represented in an AVX2-friendly format.
 #[derive(Copy, Clone, Debug)]
@@ -66,13 +63,7 @@ impl Default for ExtendedPoint {
 
 impl Identity for ExtendedPoint {
     fn identity() -> ExtendedPoint {
-        ExtendedPoint(FieldElement32x4([
-            u32x8::new(0, 1, 0, 0, 1, 0, 0, 0),
-            u32x8::splat(0),
-            u32x8::splat(0),
-            u32x8::splat(0),
-            u32x8::splat(0),
-        ]))
+        constants::EXTENDEDPOINT_IDENTITY
     }
 }
 
@@ -172,13 +163,7 @@ impl Default for CachedPoint {
 
 impl Identity for CachedPoint {
     fn identity() -> CachedPoint {
-        CachedPoint(FieldElement32x4([
-            u32x8::new(121647, 121666, 0, 0, 243332, 67108845, 0, 33554431),
-            u32x8::new(67108864, 0, 33554431, 0, 0, 67108863, 0, 33554431),
-            u32x8::new(67108863, 0, 33554431, 0, 0, 67108863, 0, 33554431),
-            u32x8::new(67108863, 0, 33554431, 0, 0, 67108863, 0, 33554431),
-            u32x8::new(67108863, 0, 33554431, 0, 0, 67108863, 0, 33554431),
-        ]))
+        constants::CACHEDPOINT_IDENTITY
     }
 }
 
diff --git a/src/backend/avx2/field.rs b/src/backend/avx2/field.rs
index d25d997..082287d 100644
--- a/src/backend/avx2/field.rs
+++ b/src/backend/avx2/field.rs
@@ -526,8 +526,6 @@ impl FieldElement32x4 {
     ///
     /// Limbs must be bounded by bit-excess \\( b < 2.0 \\).
     pub fn square_and_negate_D(&self) -> FieldElement32x4 {
-        let neg_mask = D_LANES64;
-
         #[inline(always)]
         fn m(x: u32x8, y: u32x8) -> u64x4 {
             use core::arch::x86_64::_mm256_mul_epu32;