Use integer RTTI/witness handles in existential tuples. (#1598)

* Use integer RTTI/witness handles in existential tuples.

* Fix clang error.

* Fix IR serialization to use 16bits for opcode.

* Undo accidental comment change.

* Use variable length encoding for opcode.

* Fix compile error.

* Fixing issues

* Fix code review issues.

1 files changed, 4 insertions, 3 deletions

diff --git a/source/slang/slang-ir-generics-lowering-context.cpp b/source/slang/slang-ir-generics-lowering-context.cpp
index bef4dbb0a..4c4224295 100644
--- a/source/slang/slang-ir-generics-lowering-context.cpp
+++ b/source/slang/slang-ir-generics-lowering-context.cpp
@@ -134,13 +134,14 @@ namespace Slang
 
         if (isTypeValue(paramType))
         {
-            return builder->getPtrType(builder->getRTTIType());
+            return builder->getRTTIHandleType();
         }
 
         IRIntegerValue anyValueSize = kInvalidAnyValueSize;
         switch (paramType->op)
         {
         case kIROp_WitnessTableType:
+        case kIROp_WitnessTableIDType:
         case kIROp_ExtractExistentialType:
             // Do not translate these types.
             return (IRType*)paramType;
@@ -174,8 +175,8 @@ namespace Slang
             // An existential type translates into a tuple of (AnyValue, WitnessTable, RTTI*)
             anyValueSize = getInterfaceAnyValueSize(paramType, paramType->sourceLoc);
             auto anyValueType = builder->getAnyValueType(anyValueSize);
-            auto witnessTableType = builder->getWitnessTableType((IRType*)paramType);
-            auto rttiType = builder->getPtrType(builder->getRTTIType());
+            auto witnessTableType = builder->getWitnessTableIDType((IRType*)paramType);
+            auto rttiType = builder->getRTTIHandleType();
             auto tupleType = builder->getTupleType(rttiType, witnessTableType, anyValueType);
             return tupleType;
         }