From 765061a77bcf4fe6300721263cc9e0f25595488d Mon Sep 17 00:00:00 2001
From: Yong He <yonghe@outlook.com>
Date: Tue, 10 May 2022 19:42:48 -0700
Subject: Initial support for COM interface in host code. (#2230)

Co-authored-by: Yong He <yhe@nvidia.com>
Co-authored-by: Theresa Foley <10618364+tangent-vector@users.noreply.github.com>
---
 source/slang/slang-ir-com-interface.cpp | 98 +++++++++++++++++++++++++++++++++
 1 file changed, 98 insertions(+)
 create mode 100644 source/slang/slang-ir-com-interface.cpp

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

diff --git a/source/slang/slang-ir-com-interface.cpp b/source/slang/slang-ir-com-interface.cpp
new file mode 100644
index 000000000..1bcf3d2b6
--- /dev/null
+++ b/source/slang/slang-ir-com-interface.cpp
@@ -0,0 +1,98 @@
+// slang-ir-com-interface.cpp
+#include "slang-ir-com-interface.h"
+
+#include "slang-ir.h"
+#include "slang-ir-insts.h"
+
+namespace Slang
+{
+
+struct ComInterfaceLoweringContext
+{
+    IRModule* module;
+    DiagnosticSink* diagnosticSink;
+
+    SharedIRBuilder sharedBuilder;
+
+    Dictionary<IRInterfaceType*, IRComPtrType*> comPtrTypes;
+
+    void replaceTypeUses(IRInst* inst, IRInst* newValue)
+    {
+        List<IRUse*> uses;
+        for (auto use = inst->firstUse; use; use = use->nextUse)
+        {
+            uses.add(use);
+        }
+        for (auto use : uses)
+        {
+            switch (use->getUser()->getOp())
+            {
+            case kIROp_WitnessTableIDType:
+            case kIROp_WitnessTableType:
+            case kIROp_ThisType:
+            case kIROp_RTTIPointerType:
+            case kIROp_RTTIHandleType:
+            case kIROp_ComPtrType:
+                continue;
+            default:
+                break;
+            }
+            use->set(newValue);
+        }
+    }
+
+    IRComPtrType* processInterfaceType(IRInterfaceType* type)
+    {
+        if (!type->findDecoration<IRComInterfaceDecoration>())
+            return nullptr;
+
+        IRComPtrType* result = nullptr;
+
+        if (comPtrTypes.TryGetValue(type, result))
+            return result;
+
+        IRBuilder builder(sharedBuilder);
+        builder.setInsertInto(module->getModuleInst());
+        result = builder.getComPtrType(type);
+
+        replaceTypeUses(type, result);
+        return result;
+    }
+
+    void processThisType(IRThisType* type)
+    {
+        auto comPtrType = processInterfaceType(as<IRInterfaceType>(type->getConstraintType()));
+        if (!comPtrType)
+            return;
+        replaceTypeUses(type, comPtrType);
+    }
+
+    void processModule()
+    {
+        for (auto child : module->getGlobalInsts())
+        {
+            switch (child->getOp())
+            {
+            case kIROp_InterfaceType:
+                processInterfaceType(as<IRInterfaceType>(child));
+                break;
+            case kIROp_ThisType:
+                processThisType(as<IRThisType>(child));
+                break;
+            default:
+                break;
+            }
+        }
+    }
+};
+
+void lowerComInterfaces(IRModule* module, DiagnosticSink* sink)
+{
+    ComInterfaceLoweringContext context;
+    context.module = module;
+    context.diagnosticSink = sink;
+    context.sharedBuilder.init(module);
+    return context.processModule();
+}
+
+}
-- 
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