4 files changed, 26 insertions, 1 deletions
diff --git a/source/slang/slang-emit.cpp b/source/slang/slang-emit.cpp
index 841f44a80..8d7577b52 100644
--- a/source/slang/slang-emit.cpp
+++ b/source/slang/slang-emit.cpp
@@ -1278,6 +1278,15 @@ Result linkAndOptimizeIR(
         //
         legalizeResourceTypes(targetProgram, irModule, sink);
 
+        // We also need to legalize empty types for Metal targets.
+        switch (target)
+        {
+        case CodeGenTarget::Metal:
+        case CodeGenTarget::MetalLib:
+        case CodeGenTarget::MetalLibAssembly:
+            legalizeEmptyTypes(targetProgram, irModule, sink);
+            break;
+        }
         //  Debugging output of legalization
 #if 0
         dumpIRIfEnabled(codeGenContext, irModule, "LEGALIZED");
diff --git a/source/slang/slang-ir-legalize-types.cpp b/source/slang/slang-ir-legalize-types.cpp
index 197cd93c5..837193abc 100644
--- a/source/slang/slang-ir-legalize-types.cpp
+++ b/source/slang/slang-ir-legalize-types.cpp
@@ -4123,6 +4123,11 @@ struct IREmptyTypeLegalizationContext : IRTypeLegalizationContext
 
     bool isSimpleType(IRType* type) override
     {
+        if (isMetalTarget(targetProgram->getTargetReq()))
+        {
+            return false;
+        }
+
         // If type is used as public interface, then treat it as simple.
         for (auto decor : type->getDecorations())
         {
@@ -4145,6 +4150,11 @@ struct IREmptyTypeLegalizationContext : IRTypeLegalizationContext
     {
         return LegalType();
     }
+
+    virtual bool shouldLegalizeParameterBlockElementType() override
+    {
+        return isMetalTarget(targetProgram->getTargetReq());
+    }
 };
 
 // The main entry points that are used when transforming IR code
diff --git a/source/slang/slang-legalize-types.cpp b/source/slang/slang-legalize-types.cpp
index e26475522..cc2c12d42 100644
--- a/source/slang/slang-legalize-types.cpp
+++ b/source/slang/slang-legalize-types.cpp
@@ -1211,11 +1211,15 @@ LegalType legalizeTypeImpl(TypeLegalizationContext* context, IRType* type)
         LegalType legalElementType;
 
         if (isMetalTarget(context->targetProgram->getTargetReq()) &&
-            as<IRParameterBlockType>(uniformBufferType))
+            as<IRParameterBlockType>(uniformBufferType) &&
+            !context->shouldLegalizeParameterBlockElementType())
         {
             // On Metal, we do not need to legalize the element type of
             // a parameter block because we can translate it directly into
             // an argument buffer.
+            //
+            // But we do need empty type legalized for Metal, because Metal doesn't
+            // allow empty struct in argument buffer.
             legalElementType = LegalType::simple(originalElementType);
         }
         else
diff --git a/source/slang/slang-legalize-types.h b/source/slang/slang-legalize-types.h
index ae76cbd39..f1b15877d 100644
--- a/source/slang/slang-legalize-types.h
+++ b/source/slang/slang-legalize-types.h
@@ -659,6 +659,8 @@ struct IRTypeLegalizationContext
         IROp op,
         LegalType legalElementType,
         IRInst* layoutOperand) = 0;
+
+    virtual bool shouldLegalizeParameterBlockElementType() { return false; }
 };
 
 // This typedef exists to support pre-existing code from when