Rework differentiation of member access through `[DerivativeMember(DiffType.field)]` (#2460)

* wip: remove auto-diff for member access, add diff through property accessors.

* Fix getter-setter test.

* Fix getter-setter-multi test.

* Fix nested-jvp test.

* Use [DerivativeMember] attribute to differentiate through member access.

* Clean up.

* More cleanup.

Co-authored-by: Yong He <yhe@nvidia.com>

4 files changed, 12 insertions, 47 deletions

diff --git a/tests/autodiff/generic-impl-jvp.slang b/tests/autodiff/generic-impl-jvp.slang
index 5bf3a25c3..fe4ffc426 100644
--- a/tests/autodiff/generic-impl-jvp.slang
+++ b/tests/autodiff/generic-impl-jvp.slang
@@ -17,15 +17,11 @@ struct dvector
 __generic<T : IDFloat, let N : int>
 struct myvector : IDifferentiable
 {
-    T values[N];
     typedef dvector<T.Differential, N> Differential;
 
-    [__unsafeForceInlineEarly]
-    static Ptr<T.Differential[N]> __getDifferentialFor_values(inout Differential d)
-    {
-        return &(d.values);
-    }
-
+    [DerivativeMember(Differential.values)]
+    T values[N];
+    
     __init(T c)
     {
         for (int i = 0; i < N; i++)
@@ -158,19 +154,9 @@ struct linearvector : MyLinearArithmeticType, IDifferentiable
 {
     typedef lineardvector<N> Differential;
 
+    [DerivativeMember(Differential.val)]
     myvector<Real, N> val;
 
-    [__unsafeForceInlineEarly]
-    static Ptr<myvector<Real, N>.Differential> __getDifferentialFor_val(inout Differential dvec)
-    {
-        return &(dvec.val);
-    }
-
-    static void __setDifferentialForVal(lineardvector<N> dvec, myvector<Real, N>.Differential v)
-    {
-        dvec.val = v;
-    }
-
     static __differentiate_jvp linearvector<N> ladd(linearvector<N> a, linearvector<N> b)
     {
         return linearvector<N>(a.val + b.val);
diff --git a/tests/autodiff/generic-jvp.slang b/tests/autodiff/generic-jvp.slang
index 54a99cae9..bcd5e764e 100644
--- a/tests/autodiff/generic-jvp.slang
+++ b/tests/autodiff/generic-jvp.slang
@@ -87,11 +87,8 @@ extension myfloat3 : IDifferentiable
 {
     typedef myfloat3 Differential;
 
-    [__unsafeForceInlineEarly]
-    static Ptr<float3> __getDifferentialFor_val(inout Differential dx)
-    {
-        return &(dx.val);
-    }
+    [DerivativeMember(Differential.val)]
+    extern vector<Real, 3> val;
 
     static Differential zero()
     {
@@ -114,11 +111,8 @@ extension myfloat4 : IDifferentiable
 {
     typedef myfloat4 Differential;
 
-    [__unsafeForceInlineEarly]
-    static Ptr<float4> __getDifferentialFor_val(inout Differential dx)
-    {
-        return &(dx.val);
-    }
+    [DerivativeMember(Differential.val)]
+    extern vector<Real, 4> val;
 
     static Differential zero()
     {
diff --git a/tests/autodiff/getter-setter-multi.slang b/tests/autodiff/getter-setter-multi.slang
index 61cb96a07..c19a3f6bb 100644
--- a/tests/autodiff/getter-setter-multi.slang
+++ b/tests/autodiff/getter-setter-multi.slang
@@ -13,23 +13,13 @@ struct B
 struct A : IDifferentiable
 {
     typedef B Differential;
-    
+
+    [DerivativeMember(B.z)]
     float3 x;
+    [DerivativeMember(B.k)]
     float y[10];
 
     [__unsafeForceInlineEarly]
-    static Ptr<float3.Differential> __getDifferentialFor_x(inout Differential b)
-    {
-        return &(b.z);
-    }
-
-    [__unsafeForceInlineEarly]
-    static Ptr<float.Differential[10]> __getDifferentialFor_y(inout Differential b)
-    {
-        return &(b.k);
-    }
-
-    [__unsafeForceInlineEarly]
     static Differential zero()
     {
         B b = {0.0};
diff --git a/tests/autodiff/getter-setter.slang b/tests/autodiff/getter-setter.slang
index 6b280433b..0e8cac13b 100644
--- a/tests/autodiff/getter-setter.slang
+++ b/tests/autodiff/getter-setter.slang
@@ -13,16 +13,11 @@ struct A : IDifferentiable
 {
     typedef B Differential;
     
+    [DerivativeMember(B.z)]
     float x;
     float y;
 
     [__unsafeForceInlineEarly]
-    static Ptr<float.Differential> __getDifferentialFor_x(inout Differential b)
-    {
-        return &(b.z);
-    }
-
-    [__unsafeForceInlineEarly]
     static Differential zero()
     {
         B b = {0.0};