Support initializing an existential value from a generic value. (#1503)

* Support initializing an existential value from a generic value.

* Remove trailing spaces and clean up debugging code.

1 files changed, 84 insertions, 0 deletions

diff --git a/source/slang/slang-ir-augment-make-existential.cpp b/source/slang/slang-ir-augment-make-existential.cpp
new file mode 100644
index 000000000..18d061276
--- /dev/null
+++ b/source/slang/slang-ir-augment-make-existential.cpp
@@ -0,0 +1,84 @@
+#include "slang-ir-augment-make-existential.h"
+#include "slang-ir-insts.h"
+#include "slang-ir.h"
+
+namespace Slang
+{
+struct AugmentMakeExistentialContext
+{
+    IRModule* module;
+
+    SharedIRBuilder sharedBuilderStorage;
+
+    List<IRInst*> workList;
+    HashSet<IRInst*> workListSet;
+
+    void addToWorkList(IRInst* inst)
+    {
+        if (workListSet.Contains(inst))
+            return;
+
+        workList.add(inst);
+        workListSet.Add(inst);
+    }
+
+    void processMakeExistential(IRMakeExistential* inst)
+    {
+        IRBuilder builderStorage;
+        auto builder = &builderStorage;
+        builder->sharedBuilder = &sharedBuilderStorage;
+        builder->setInsertBefore(inst);
+
+        auto augInst = builder->emitMakeExistentialWithRTTI(
+            inst->getFullType(),
+            inst->getWrappedValue(),
+            inst->getWitnessTable(),
+            inst->getWrappedValue()->getDataType());
+        inst->replaceUsesWith(augInst);
+        inst->removeAndDeallocate();
+    }
+
+    void processInst(IRInst* inst)
+    {
+        switch (inst->op)
+        {
+        case kIROp_MakeExistential:
+            processMakeExistential((IRMakeExistential*)inst);
+            break;
+        default:
+            break;
+        }
+    }
+
+    void processModule()
+    {
+        SharedIRBuilder* sharedBuilder = &sharedBuilderStorage;
+        sharedBuilder->module = module;
+        sharedBuilder->session = module->session;
+
+        addToWorkList(module->getModuleInst());
+
+        while (workList.getCount() != 0)
+        {
+            IRInst* inst = workList.getLast();
+
+            workList.removeLast();
+            workListSet.Remove(inst);
+
+            processInst(inst);
+
+            for (auto child = inst->getLastChild(); child; child = child->getPrevInst())
+            {
+                addToWorkList(child);
+            }
+        }
+    }
+};
+
+void augmentMakeExistentialInsts(IRModule* module)
+{
+    AugmentMakeExistentialContext context;
+    context.module = module;
+    context.processModule();
+}
+} // namespace Slang