Revert "Eliminate empty struct on metal target (#6603)" (#6711)

This reverts commit b3deec2001ea34e20e9a6af8ddf5cf3866cafac0.

5 files changed, 1 insertions, 59 deletions

diff --git a/source/slang/slang-emit.cpp b/source/slang/slang-emit.cpp
index 8d7577b52..841f44a80 100644
--- a/source/slang/slang-emit.cpp
+++ b/source/slang/slang-emit.cpp
@@ -1278,15 +1278,6 @@ 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 837193abc..197cd93c5 100644
--- a/source/slang/slang-ir-legalize-types.cpp
+++ b/source/slang/slang-ir-legalize-types.cpp
@@ -4123,11 +4123,6 @@ 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())
         {
@@ -4150,11 +4145,6 @@ 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 cc2c12d42..e26475522 100644
--- a/source/slang/slang-legalize-types.cpp
+++ b/source/slang/slang-legalize-types.cpp
@@ -1211,15 +1211,11 @@ LegalType legalizeTypeImpl(TypeLegalizationContext* context, IRType* type)
         LegalType legalElementType;
 
         if (isMetalTarget(context->targetProgram->getTargetReq()) &&
-            as<IRParameterBlockType>(uniformBufferType) &&
-            !context->shouldLegalizeParameterBlockElementType())
+            as<IRParameterBlockType>(uniformBufferType))
         {
             // 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 f1b15877d..ae76cbd39 100644
--- a/source/slang/slang-legalize-types.h
+++ b/source/slang/slang-legalize-types.h
@@ -659,8 +659,6 @@ struct IRTypeLegalizationContext
         IROp op,
         LegalType legalElementType,
         IRInst* layoutOperand) = 0;
-
-    virtual bool shouldLegalizeParameterBlockElementType() { return false; }
 };
 
 // This typedef exists to support pre-existing code from when
diff --git a/tests/metal/empty-struct-remove.slang b/tests/metal/empty-struct-remove.slang
deleted file mode 100644
index 2d9ee436b..000000000
--- a/tests/metal/empty-struct-remove.slang
+++ /dev/null
@@ -1,33 +0,0 @@
-
-//TEST:SIMPLE(filecheck=LIB):-target metallib -entry computeMain -stage compute -DMETAL
-//TEST:SIMPLE(filecheck=METAL):-target metal -entry computeMain -stage compute -DMETAL
-
-// METAL-NOT: struct emptyStruct
-struct emptyStruct
-{
-    void set(RWStructuredBuffer<int> buffer, int value) {buffer[0] = value;}
-}
-
-
-struct MyStruct
-{
-    RWStructuredBuffer<int> buffer;
-    int value;
-    void set()
-    {
-        e.set(buffer, value);
-    }
-    emptyStruct e;
-}
-
-ParameterBlock<MyStruct> param;
-
-// LIB: @computeMain
-[shader("compute")]
-[numthreads(1, 1, 1)]
-void computeMain(
-    uint tid: SV_DispatchThreadID,
-)
-{
-    param.set();
-}