Add `IDifferentiablePtrType` support for arrays (#5576)

* Add `IDifferentiablePtrType` support for arrays

- Also fixes an issue with spirv-emit of constructors that contain references to global params

* Fix GLSL legalization for arrays of resource types

4 files changed, 22 insertions, 4 deletions

diff --git a/source/slang/diff.meta.slang b/source/slang/diff.meta.slang
index 6042ff5cc..1200aef42 100644
--- a/source/slang/diff.meta.slang
+++ b/source/slang/diff.meta.slang
@@ -1241,6 +1241,12 @@ extension Array<T, N> : IDifferentiable
     }
 }
 
+__generic<T : IDifferentiablePtrType, let N : int>
+extension Array<T, N> : IDifferentiablePtrType
+{
+    typedef Array<T.Differential, N> Differential;
+}
+
 __generic<each T : IDifferentiable>
 extension Tuple<T> : IDifferentiable
 {
diff --git a/source/slang/slang-ir-autodiff.cpp b/source/slang/slang-ir-autodiff.cpp
index cb37b6242..5c05b0811 100644
--- a/source/slang/slang-ir-autodiff.cpp
+++ b/source/slang/slang-ir-autodiff.cpp
@@ -1275,7 +1275,9 @@ IRInst* DifferentiableTypeConformanceContext::buildArrayWitness(
     IRWitnessTable* table = nullptr;
     if (target == DiffConformanceKind::Value)
     {
-        SLANG_ASSERT(isDifferentiableValueType((IRType*)arrayType));
+        if (!isDifferentiableValueType((IRType*)arrayType))
+            return nullptr;
+
         auto innerWitness = tryGetDifferentiableWitness(
             builder,
             as<IRArrayTypeBase>(arrayType)->getElementType(),
@@ -1360,7 +1362,8 @@ IRInst* DifferentiableTypeConformanceContext::buildArrayWitness(
     }
     else if (target == DiffConformanceKind::Ptr)
     {
-        SLANG_ASSERT(isDifferentiablePtrType((IRType*)arrayType));
+        if (!isDifferentiablePtrType((IRType*)arrayType))
+            return nullptr;
 
         table = builder->createWitnessTable(
             sharedContext->differentiablePtrInterfaceType,
diff --git a/source/slang/slang-ir-specialize-resources.cpp b/source/slang/slang-ir-specialize-resources.cpp
index 56f468ac7..22cd9cb3f 100644
--- a/source/slang/slang-ir-specialize-resources.cpp
+++ b/source/slang/slang-ir-specialize-resources.cpp
@@ -1308,6 +1308,9 @@ bool specializeResourceUsage(CodeGenContext* codeGenContext, IRModule* irModule)
 
 bool isIllegalGLSLParameterType(IRType* type)
 {
+    if (auto arrayType = as<IRArrayTypeBase>(type))
+        return isIllegalGLSLParameterType(arrayType->getElementType());
+
     if (as<IRParameterGroupType>(type))
         return true;
     if (as<IRHLSLStructuredBufferTypeBase>(type))
diff --git a/source/slang/slang-ir-spirv-legalize.cpp b/source/slang/slang-ir-spirv-legalize.cpp
index 4baa28d67..1de2edd4a 100644
--- a/source/slang/slang-ir-spirv-legalize.cpp
+++ b/source/slang/slang-ir-spirv-legalize.cpp
@@ -1465,15 +1465,21 @@ struct SPIRVLegalizationContext : public SourceEmitterBase
 
     void maybeHoistConstructInstToGlobalScope(IRInst* inst)
     {
-        // If all of the operands to this instruction are global, we can hoist
-        // this constructor to be a global too. This is important to make sure
+        // If all of the operands to this instruction are global, and are not global
+        // variables, we can hoist this constructor to be a global too.
+        // This is important to make sure
         // that vectors made of constant components end up being emitted as
         // constant vectors (using OpConstantComposite).
         UIndex opIndex = 0;
         for (auto operand = inst->getOperands(); opIndex < inst->getOperandCount();
              operand++, opIndex++)
+        {
             if (operand->get()->getParent() != m_module->getModuleInst())
                 return;
+
+            if (as<IRGlobalParam>(operand->get()))
+                return;
+        }
         inst->insertAtEnd(m_module->getModuleInst());
     }