From 78517dc392f0d2ebba25f0ac3f4d4e004b0f0ab0 Mon Sep 17 00:00:00 2001
From: Sai Praveen Bangaru <31557731+saipraveenb25@users.noreply.github.com>
Date: Fri, 14 Mar 2025 17:15:36 -0700
Subject: Fix lowering of associated types in generic interfaces (#6600)

* Fix lowering of associated types in generic interfaces.

* Update diff-assoctype-generic-interface.slang

* Fix-up lowering of differentiable witnesses for implicit ops

* Update slang-ir-autodiff-transcriber-base.cpp

* Fix issue with differentiating type-packs
---
 source/slang/slang-ir-autodiff.cpp | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

(limited to 'source/slang/slang-ir-autodiff.cpp')

diff --git a/source/slang/slang-ir-autodiff.cpp b/source/slang/slang-ir-autodiff.cpp
index df657476a..f3f32add2 100644
--- a/source/slang/slang-ir-autodiff.cpp
+++ b/source/slang/slang-ir-autodiff.cpp
@@ -1362,9 +1362,10 @@ IRInst* DifferentiableTypeConformanceContext::lookUpInterfaceMethod(
     IRBuilder* builder,
     IRType* origType,
     IRStructKey* key,
-    IRType* resultType)
+    IRType* resultType,
+    DiffConformanceKind kind)
 {
-    if (auto conformance = tryGetDifferentiableWitness(builder, origType, DiffConformanceKind::Any))
+    if (auto conformance = tryGetDifferentiableWitness(builder, origType, kind))
         return _lookupWitness(builder, conformance, key, resultType);
     return nullptr;
 }
@@ -2097,8 +2098,6 @@ IRInst* DifferentiableTypeConformanceContext::buildTupleWitness(
     IRWitnessTable* table = nullptr;
     if (target == DiffConformanceKind::Value)
     {
-        SLANG_ASSERT(isDifferentiableValueType((IRType*)inTupleType));
-
         auto addMethod = builder->createFunc();
         auto zeroMethod = builder->createFunc();
 
@@ -2138,6 +2137,8 @@ IRInst* DifferentiableTypeConformanceContext::buildTupleWitness(
                     &b,
                     (IRType*)elementType,
                     DiffConformanceKind::Value);
+
+                SLANG_ASSERT(isDifferentiableValueType((IRType*)elementType));
                 IRInst* elementResult = nullptr;
                 if (!innerWitness)
                 {
@@ -2171,9 +2172,9 @@ IRInst* DifferentiableTypeConformanceContext::buildTupleWitness(
         {
             // Zero method.
             IRBuilder b = *builder;
-            b.setInsertInto(addMethod);
-            b.addBackwardDifferentiableDecoration(addMethod);
-            addMethod->setFullType(b.getFuncType(0, nullptr, diffTupleType));
+            b.setInsertInto(zeroMethod);
+            b.addBackwardDifferentiableDecoration(zeroMethod);
+            zeroMethod->setFullType(b.getFuncType(0, nullptr, diffTupleType));
             b.emitBlock();
             List<IRInst*> results;
             for (UInt i = 0; i < inTupleType->getOperandCount(); i++)
@@ -2214,7 +2215,6 @@ IRInst* DifferentiableTypeConformanceContext::buildTupleWitness(
     else if (target == DiffConformanceKind::Ptr)
     {
         SLANG_ASSERT(isDifferentiablePtrType((IRType*)inTupleType));
-
         table = builder->createWitnessTable(
             sharedContext->differentiablePtrInterfaceType,
             (IRType*)inTupleType);
-- 
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