1 files changed, 114 insertions, 0 deletions
diff --git a/source/slang/ir-existential.cpp b/source/slang/ir-existential.cpp
new file mode 100644
index 000000000..af15472bf
--- /dev/null
+++ b/source/slang/ir-existential.cpp
@@ -0,0 +1,114 @@
+// ir-existential.cpp
+#include "ir-existential.h"
+
+#include "ir.h"
+#include "ir-insts.h"
+
+namespace Slang {
+
+struct ExistentialTypeSimplificationContext
+{
+    List<IRInst*> instsToRemove;
+
+};
+
+void simplifyExistentialTypesRec(
+    ExistentialTypeSimplificationContext*   context,
+    IRInst*                                 inst)
+{
+    switch( inst->op )
+    {
+    default:
+        break;
+
+    case kIROp_ExtractExistentialValue:
+        {
+            auto arg = inst->getOperand(0);
+            if( auto makeExistential = as<IRMakeExistential>(arg) )
+            {
+                auto value = makeExistential->getWrappedValue();
+                inst->replaceUsesWith(value);
+                context->instsToRemove.Add(inst);
+            }
+        }
+        break;
+
+    case kIROp_ExtractExistentialType:
+        {
+            auto arg = inst->getOperand(0);
+            if( auto makeExistential = as<IRMakeExistential>(arg) )
+            {
+                auto value = makeExistential->getWrappedValue();
+                inst->replaceUsesWith(value->getFullType());
+                context->instsToRemove.Add(inst);
+            }
+        }
+        break;
+
+    case kIROp_ExtractExistentialWitnessTable:
+        {
+            auto arg = inst->getOperand(0);
+            if( auto makeExistential = as<IRMakeExistential>(arg) )
+            {
+                auto witnessTable = makeExistential->getWitnessTable();
+                inst->replaceUsesWith(witnessTable);
+                context->instsToRemove.Add(inst);
+            }
+        }
+        break;
+    }
+
+    for( auto childInst : inst->getChildren() )
+    {
+        simplifyExistentialTypesRec(context, childInst);
+    }
+}
+
+void removeUnusedExistentialsRec(
+    ExistentialTypeSimplificationContext*   context,
+    IRInst*                                 inst)
+{
+    switch( inst->op )
+    {
+    default:
+        break;
+
+    case kIROp_MakeExistential:
+        {
+            if( !inst->hasUses() )
+            {
+                context->instsToRemove.Add(inst);
+            }
+        }
+        break;
+    }
+
+    for( auto childInst : inst->getChildren() )
+    {
+        removeUnusedExistentialsRec(context, childInst);
+    }
+}
+
+void simplifyExistentialTypes(
+    IRModule*   module)
+{
+    {
+        ExistentialTypeSimplificationContext context;
+        simplifyExistentialTypesRec(&context, module->getModuleInst());
+        for( auto inst : context.instsToRemove )
+        {
+            inst->removeAndDeallocate();
+        }
+    }
+
+    {
+        ExistentialTypeSimplificationContext context;
+        removeUnusedExistentialsRec(&context, module->getModuleInst());
+        for( auto inst : context.instsToRemove )
+        {
+            inst->removeAndDeallocate();
+        }
+    }
+}
+
+} // namespace Slang