From e0f3ed3fd8be3513755daf8b9bfbcb6310cebfb3 Mon Sep 17 00:00:00 2001
From: Magnus Ulimoen <flymagnus@gmail.com>
Date: Thu, 14 Nov 2019 08:04:32 +0100
Subject: [PATCH] assign instead of add_assign in diffx/diffy

---
 src/maxwell.rs           | 14 ++++++--------
 src/operators/upwind4.rs | 33 +++++++++++++++------------------
 2 files changed, 21 insertions(+), 26 deletions(-)

diff --git a/src/maxwell.rs b/src/maxwell.rs
index fda2498..ae8409b 100644
--- a/src/maxwell.rs
+++ b/src/maxwell.rs
@@ -79,21 +79,19 @@ impl System {
                 }
             };
 
+            // hz = -ey_x + ex_y
+            let tmp = &mut k[i].0;
+            SBP::diffx(y.2.view(), tmp.view_mut());
+            SBP::diffy(y.0.view(), k[i].1.view_mut());
+            k[i].1.scaled_add(-1.0, tmp);
+
             // ex = hz_y
-            k[i].0.fill(0.0);
             SBP::diffy(y.1.view(), k[i].0.view_mut());
 
             // ey = -hz_x
-            k[i].2.fill(0.0);
             SBP::diffx(y.1.view(), k[i].2.view_mut());
             k[i].2.mapv_inplace(|v| -v);
 
-            // hz = -ey_x + ex_y
-            k[i].1.fill(0.0);
-            SBP::diffx(y.2.view(), k[i].1.view_mut());
-            k[i].1.mapv_inplace(|v| -v);
-            SBP::diffy(y.0.view(), k[i].1.view_mut());
-
             // Boundary conditions (SAT)
             let ny = y.0.shape()[0];
             let nx = y.0.shape()[1];
diff --git a/src/operators/upwind4.rs b/src/operators/upwind4.rs
index 7dc0ab5..8fe0351 100644
--- a/src/operators/upwind4.rs
+++ b/src/operators/upwind4.rs
@@ -105,10 +105,10 @@ impl Upwind4 {
             ),
         ];
         unsafe {
-            *fut.get_unchecked_mut(0) += idx * (block[0] * first_elems).sum();
-            *fut.get_unchecked_mut(1) += idx * (block[1] * first_elems).sum();
-            *fut.get_unchecked_mut(2) += idx * (block[2] * first_elems).sum();
-            *fut.get_unchecked_mut(3) += idx * (block[3] * first_elems).sum()
+            *fut.get_unchecked_mut(0) = idx * (block[0] * first_elems).sum();
+            *fut.get_unchecked_mut(1) = idx * (block[1] * first_elems).sum();
+            *fut.get_unchecked_mut(2) = idx * (block[2] * first_elems).sum();
+            *fut.get_unchecked_mut(3) = idx * (block[3] * first_elems).sum()
         };
 
         let diag = f32x8::new(
@@ -131,16 +131,16 @@ impl Upwind4 {
             )
             .take(nx - 2 * block.len())
         {
-            *f += idx * (p * diag).sum();
+            *f = idx * (p * diag).sum();
         }
 
         let last_elems = unsafe { f32x8::from_slice_unaligned_unchecked(&prev[nx - 8..]) }
             .shuffle1_dyn(u32x8::new(7, 6, 5, 4, 3, 2, 1, 0));
         unsafe {
-            *fut.get_unchecked_mut(nx - 4) += -idx * (block[3] * last_elems).sum();
-            *fut.get_unchecked_mut(nx - 3) += -idx * (block[2] * last_elems).sum();
-            *fut.get_unchecked_mut(nx - 2) += -idx * (block[1] * last_elems).sum();
-            *fut.get_unchecked_mut(nx - 1) += -idx * (block[0] * last_elems).sum();
+            *fut.get_unchecked_mut(nx - 4) = -idx * (block[3] * last_elems).sum();
+            *fut.get_unchecked_mut(nx - 3) = -idx * (block[2] * last_elems).sum();
+            *fut.get_unchecked_mut(nx - 2) = -idx * (block[1] * last_elems).sum();
+            *fut.get_unchecked_mut(nx - 1) = -idx * (block[0] * last_elems).sum();
         }
     }
 
@@ -167,8 +167,7 @@ impl Upwind4 {
             ];
 
             for (i, bl) in Self::BLOCK.iter().enumerate() {
-                let mut b = f32x4::from_slice_unaligned(&fut[i * nx + j..]);
-                b += idy
+                let b = idy
                     * (a[0] * bl[0]
                         + a[1] * bl[1]
                         + a[2] * bl[2]
@@ -191,8 +190,7 @@ impl Upwind4 {
                     a[6],
                     f32x4::from_slice_unaligned(&prev[nx * (i + 3) + j..]),
                 ];
-                let mut b = f32x4::from_slice_unaligned(&fut[nx * i + j..]);
-                b += idy
+                let b = idy
                     * (a[0] * Self::DIAG[0]
                         + a[1] * Self::DIAG[1]
                         + a[2] * Self::DIAG[2]
@@ -214,8 +212,7 @@ impl Upwind4 {
             ];
 
             for (i, bl) in Self::BLOCK.iter().enumerate() {
-                let mut b = f32x4::from_slice_unaligned(&fut[(ny - 1 - i) * nx + j..]);
-                b += -idy
+                let b = -idy
                     * (a[0] * bl[0]
                         + a[1] * bl[1]
                         + a[2] * bl[2]
@@ -246,7 +243,7 @@ impl Upwind4 {
         let first_elems = prev.slice(s!(..7));
         for (bl, f) in block.outer_iter().zip(&mut fut) {
             let diff = first_elems.dot(&bl);
-            *f += diff * idx;
+            *f = diff * idx;
         }
 
         for (window, f) in prev
@@ -257,13 +254,13 @@ impl Upwind4 {
             .take(nx - 8)
         {
             let diff = diag.dot(&window);
-            *f += diff * idx;
+            *f = diff * idx;
         }
 
         let last_elems = prev.slice(s!(nx - 7..;-1));
         for (bl, f) in block.outer_iter().zip(&mut fut.slice_mut(s![nx - 4..;-1])) {
             let diff = -bl.dot(&last_elems);
-            *f += diff * idx;
+            *f = diff * idx;
         }
     }
 }