From bdcd58043ccb85b1a88d29aa5c79d5ce4c7ac937 Mon Sep 17 00:00:00 2001
From: efremale <alexsl1@icloud.com>
Date: Mon, 13 Jul 2020 21:50:08 +0200
Subject: [PATCH 1/5] Add failing test

---
 test/AutoDiff/validation-test/forward_mode.swift | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/test/AutoDiff/validation-test/forward_mode.swift b/test/AutoDiff/validation-test/forward_mode.swift
index b75cc1645d59e..750b8b7f3c036 100644
--- a/test/AutoDiff/validation-test/forward_mode.swift
+++ b/test/AutoDiff/validation-test/forward_mode.swift
@@ -1599,6 +1599,9 @@ ForwardModeTests.test("Generics") {
 
   // FIXME(SR-13210): Fix forward-mode SIL verification error.
   /*
+  let a = SIMD3<Double>(1, 2, 3)
+  let g = SIMD3<Double>(1, 1, 1)
+
   func testInit<Scalar, SIMDType: SIMD>(x: Scalar) -> SIMDType
     where SIMDType.Scalar == Scalar,
           SIMDType : Differentiable,

From eeed1d8dc29782533f7f05b5ac3d25bf95d89ca4 Mon Sep 17 00:00:00 2001
From: Dan Zheng <danielzheng@google.com>
Date: Mon, 13 Jul 2020 14:05:23 -0700
Subject: [PATCH 2/5] Narrow down SR-13210 failing test.

---
 test/AutoDiff/validation-test/forward_mode.swift | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/test/AutoDiff/validation-test/forward_mode.swift b/test/AutoDiff/validation-test/forward_mode.swift
index 750b8b7f3c036..b75cc1645d59e 100644
--- a/test/AutoDiff/validation-test/forward_mode.swift
+++ b/test/AutoDiff/validation-test/forward_mode.swift
@@ -1599,9 +1599,6 @@ ForwardModeTests.test("Generics") {
 
   // FIXME(SR-13210): Fix forward-mode SIL verification error.
   /*
-  let a = SIMD3<Double>(1, 2, 3)
-  let g = SIMD3<Double>(1, 1, 1)
-
   func testInit<Scalar, SIMDType: SIMD>(x: Scalar) -> SIMDType
     where SIMDType.Scalar == Scalar,
           SIMDType : Differentiable,

From ece04f24d5b6ea7728ab999a895c9242093ac115 Mon Sep 17 00:00:00 2001
From: efremale <alexsl1@icloud.com>
Date: Fri, 17 Jul 2020 22:25:21 +0000
Subject: [PATCH 3/5] Fix a bug in `_jvpMultiply`

---
 stdlib/public/Differentiation/SIMDDifferentiation.swift.gyb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/stdlib/public/Differentiation/SIMDDifferentiation.swift.gyb b/stdlib/public/Differentiation/SIMDDifferentiation.swift.gyb
index e4110340ad696..9eee9b6f22b8b 100644
--- a/stdlib/public/Differentiation/SIMDDifferentiation.swift.gyb
+++ b/stdlib/public/Differentiation/SIMDDifferentiation.swift.gyb
@@ -176,7 +176,7 @@ where
     )
   {
     return (lhs * rhs, { ltan, rtan in
-      return lhs * ltan + rtan * rhs
+      return lhs * rtan + ltan * rhs
     })
   }
 

From ae664c3aa3b00159bc1a6e6dc4249d9ed19dfb6e Mon Sep 17 00:00:00 2001
From: efremale <alexsl1@icloud.com>
Date: Mon, 20 Jul 2020 19:21:56 +0000
Subject: [PATCH 4/5] Improve multiplication test

---
 test/AutoDiff/validation-test/forward_mode.swift | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/test/AutoDiff/validation-test/forward_mode.swift b/test/AutoDiff/validation-test/forward_mode.swift
index b75cc1645d59e..a17b750feae26 100644
--- a/test/AutoDiff/validation-test/forward_mode.swift
+++ b/test/AutoDiff/validation-test/forward_mode.swift
@@ -1537,15 +1537,17 @@ ForwardModeTests.test("Subtraction") {
 
 ForwardModeTests.test("Multiplication") {
   let a = SIMD4<Float>(1, 2, 3, 4)
+  let a2 = SIMD4<Float>(4, 3, 2, 1)
   let g = SIMD4<Float>(1, 1, 1, 1)
+  let g2 = SIMD4<Float>(0, 2, 1, 3)
 
   // SIMD * SIMD
   func foo1(x: SIMD4<Float>, y: SIMD4<Float>) -> SIMD4<Float> {
     return x * y
   }
-  let (val1, df1) = valueWithDifferential(at: a, a, in: foo1)
-  expectEqual(a * a, val1)
-  expectEqual(a * g + g * a, df1(g, g))
+  let (val1, df1) = valueWithDifferential(at: a, b, in: foo1)
+  expectEqual(a * b, val1)
+  expectEqual(a * g2 + g * b, df1(g, g2))
 
   // SIMD * Scalar
   func foo2(x: SIMD4<Float>, y: Float) -> SIMD4<Float> {

From 094b0c1ca30ed1d6380d178cd0994911317f363a Mon Sep 17 00:00:00 2001
From: Dan Zheng <danielzheng@google.com>
Date: Tue, 21 Jul 2020 09:31:36 -0700
Subject: [PATCH 5/5] Update test/AutoDiff/validation-test/forward_mode.swift

---
 test/AutoDiff/validation-test/forward_mode.swift | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/test/AutoDiff/validation-test/forward_mode.swift b/test/AutoDiff/validation-test/forward_mode.swift
index a17b750feae26..c29b87f34c198 100644
--- a/test/AutoDiff/validation-test/forward_mode.swift
+++ b/test/AutoDiff/validation-test/forward_mode.swift
@@ -1545,9 +1545,9 @@ ForwardModeTests.test("Multiplication") {
   func foo1(x: SIMD4<Float>, y: SIMD4<Float>) -> SIMD4<Float> {
     return x * y
   }
-  let (val1, df1) = valueWithDifferential(at: a, b, in: foo1)
-  expectEqual(a * b, val1)
-  expectEqual(a * g2 + g * b, df1(g, g2))
+  let (val1, df1) = valueWithDifferential(at: a, a2, in: foo1)
+  expectEqual(a * a2, val1)
+  expectEqual(a * g2 + g * a2, df1(g, g2))
 
   // SIMD * Scalar
   func foo2(x: SIMD4<Float>, y: Float) -> SIMD4<Float> {