Clean up unused code for IR object ownership (#1416)

There was a small but non-trivial amount of code across `IRModule`, the `ObjectScopeManager`, and `StringRepresentationCache` that had to do with managing the lifetimes of `RefObject`s that might be referenced by IR instructions (and thus need to be kept alive for the lifetime of the IR module).

We have long since migrated to a model where IR instruction do not include owned references to `RefObject`s, so these facilities weren't actually needed. This streamlines `IRModule`'s declaration, and trims code that we aren't actually using.

One note for the future is that the `StringRepresentationCache` no longer does what its name implies (it is not a cache of `StringRepresentation`s), so we should consider giving it a more narrowly scoped name. I didn't include that in this change because I wanted to keep the diffs narrow and easy to review.

A follow-on renaming change should be trivial if/when we can agree on what the type should be called at this point. Alternatively, we could simply bake the functionality of `StringRepresentationCache` into he IR deserialiation logic itself, since that is the only code using it.

10 files changed, 9 insertions, 215 deletions

diff --git a/source/core/core.vcxproj b/source/core/core.vcxproj
index 636edb46a..8c4e7753c 100644
--- a/source/core/core.vcxproj
+++ b/source/core/core.vcxproj
@@ -189,7 +189,6 @@
     <ClInclude Include="slang-math.h" />
     <ClInclude Include="slang-memory-arena.h" />
     <ClInclude Include="slang-nvrtc-compiler.h" />
-    <ClInclude Include="slang-object-scope-manager.h" />
     <ClInclude Include="slang-offset-container.h" />
     <ClInclude Include="slang-platform.h" />
     <ClInclude Include="slang-process-util.h" />
@@ -225,7 +224,6 @@
     <ClCompile Include="slang-io.cpp" />
     <ClCompile Include="slang-memory-arena.cpp" />
     <ClCompile Include="slang-nvrtc-compiler.cpp" />
-    <ClCompile Include="slang-object-scope-manager.cpp" />
     <ClCompile Include="slang-offset-container.cpp" />
     <ClCompile Include="slang-platform.cpp" />
     <ClCompile Include="slang-random-generator.cpp" />
diff --git a/source/core/core.vcxproj.filters b/source/core/core.vcxproj.filters
index 49d8a1065..312c24b17 100644
--- a/source/core/core.vcxproj.filters
+++ b/source/core/core.vcxproj.filters
@@ -66,9 +66,6 @@
     <ClInclude Include="slang-nvrtc-compiler.h">
       <Filter>Header Files</Filter>
     </ClInclude>
-    <ClInclude Include="slang-object-scope-manager.h">
-      <Filter>Header Files</Filter>
-    </ClInclude>
     <ClInclude Include="slang-offset-container.h">
       <Filter>Header Files</Filter>
     </ClInclude>
@@ -170,9 +167,6 @@
     <ClCompile Include="slang-nvrtc-compiler.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
-    <ClCompile Include="slang-object-scope-manager.cpp">
-      <Filter>Source Files</Filter>
-    </ClCompile>
     <ClCompile Include="slang-offset-container.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
diff --git a/source/core/slang-object-scope-manager.cpp b/source/core/slang-object-scope-manager.cpp
deleted file mode 100644
index 2e7b7dfe3..000000000
--- a/source/core/slang-object-scope-manager.cpp
+++ /dev/null
@@ -1,23 +0,0 @@
-#include "slang-object-scope-manager.h"
-
-namespace Slang {
-
-void ObjectScopeManager::_releaseAll()
-{
-    RefObject*const* objs = m_objs.begin();
-    const Index numObjs = m_objs.getCount();
-    for (Index i = 0; i < numObjs; ++i)
-    {
-        objs[i]->decreaseReference();
-    }
-}
-
-void ObjectScopeManager::clear()
-{
-    _releaseAll();
-    // Free the memory as well as resizing
-    m_objs = List<RefObject*>();
-}
-
-} // namespace Slang
-
diff --git a/source/core/slang-object-scope-manager.h b/source/core/slang-object-scope-manager.h
deleted file mode 100644
index 9930e46ea..000000000
--- a/source/core/slang-object-scope-manager.h
+++ /dev/null
@@ -1,67 +0,0 @@
-#ifndef SLANG_CORE_OBJECT_SCOPE_MANAGER_H
-#define SLANG_CORE_OBJECT_SCOPE_MANAGER_H
-
-#include "slang-smart-pointer.h"
-#include "slang-list.h"
-
-namespace Slang {
-
-/** Keep objects added in scope.
-
-This is currently about the most simple implementation possible. Objects are added to a list
-which members are released when ObjectScopeManager loses scope, or clear is called. 
-
-The same object can be added multiple times. This implementation will just add the same object
-multiple times. A more complex implementation might notice that the object is already in scope
-and not add a reference. 
-
-Another potential improvement would be to hold the pointers in a MemoryArena. Doing so would remove
-the requirement of a List of contiguous memory. 
-
-In implementations that can hold multiple references to the same thing, we may want to add some 
-garbage collection to remove repeat references.
-*/
-struct ObjectScopeManager
-{
-public:
-
-        /// Add an object which will be kept in scope until manager is destroyed
-    SLANG_INLINE RefObject* add(RefObject* obj);
-        /// Add an object, where it may be nullptr. If it null its a no-op
-    SLANG_INLINE RefObject* addMaybeNull(RefObject* obj);
-
-        /// Clear the contents
-    void clear();
-
-        /// Dtor
-    ~ObjectScopeManager() { _releaseAll(); }
-
-protected:
-    void _releaseAll();
-
-    List<RefObject*> m_objs;
-};
-
-// ---------------------------------------------------------------------------
-RefObject* ObjectScopeManager::addMaybeNull(RefObject* obj)
-{
-    if (obj)
-    {
-        obj->addReference();
-        m_objs.add(obj);
-    }
-    return obj;
-}
-
-// ---------------------------------------------------------------------------
-RefObject* ObjectScopeManager::add(RefObject* obj)
-{
-    SLANG_ASSERT(obj);
-    obj->addReference();
-    m_objs.add(obj);
-    return obj;
-}
-
-} // namespace Slang
-
-#endif // SLANG_OBJECT_SCOPE_MANAGER_H
diff --git a/source/slang/slang-ir-insts.h b/source/slang/slang-ir-insts.h
index f3a0688a7..c74dfb4ea 100644
--- a/source/slang/slang-ir-insts.h
+++ b/source/slang/slang-ir-insts.h
@@ -1520,10 +1520,6 @@ struct SharedIRBuilder
     Dictionary<IRInstKey,       IRInst*>    globalValueNumberingMap;
     Dictionary<IRConstantKey,   IRConstant*>    constantMap;
 
-    // TODO: We probably shouldn't use this in the long run.
-    Dictionary<void*,           IRLayout*>        layoutMap;
-
-
     void insertBlockAlongEdge(IREdge const& edge);
 };
 
@@ -2079,13 +2075,6 @@ struct IRBuilder
         return addDecoration(value, op, operands, SLANG_COUNT_OF(operands));
     }
 
-    template <typename T>
-    T* addRefObjectToFree(T* ptr)
-    {
-        getModule()->getObjectScopeManager()->addMaybeNull(ptr);
-        return ptr;
-    }
-
     template<typename T>
     void addSimpleDecoration(IRInst* value)
     {
diff --git a/source/slang/slang-ir-serialize-types.cpp b/source/slang/slang-ir-serialize-types.cpp
index a9d9baae0..b57c46b58 100644
--- a/source/slang/slang-ir-serialize-types.cpp
+++ b/source/slang/slang-ir-serialize-types.cpp
@@ -64,17 +64,13 @@ struct CharReader
 // !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! StringRepresentationCache !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
 StringRepresentationCache::StringRepresentationCache():
-    m_stringTable(nullptr),
-    m_namePool(nullptr),
-    m_scopeManager(nullptr)
+    m_stringTable(nullptr)
 {
 }
 
-void StringRepresentationCache::init(const List<char>* stringTable, NamePool* namePool, ObjectScopeManager* scopeManager)
+void StringRepresentationCache::init(const List<char>* stringTable)
 {
     m_stringTable = stringTable;
-    m_namePool = namePool;
-    m_scopeManager = scopeManager;
 
     // Decode the table
     m_entries.setCount(StringSlicePool::kDefaultHandlesCount);
@@ -84,13 +80,11 @@ void StringRepresentationCache::init(const List<char>* stringTable, NamePool* na
         Entry& entry = m_entries[0];
         entry.m_numChars = 0;
         entry.m_startIndex = 0;
-        entry.m_object = nullptr;
     }
     {
         Entry& entry = m_entries[1];
         entry.m_numChars = 0;
         entry.m_startIndex = 0;
-        entry.m_object = nullptr;
     }
 
     {
@@ -106,7 +100,6 @@ void StringRepresentationCache::init(const List<char>* stringTable, NamePool* na
             Entry entry;
             entry.m_startIndex = uint32_t(reader.m_pos - start);
             entry.m_numChars = len;
-            entry.m_object = nullptr;
 
             m_entries.add(entry);
 
@@ -117,38 +110,6 @@ void StringRepresentationCache::init(const List<char>* stringTable, NamePool* na
     m_entries.compress();
 }
 
-Name* StringRepresentationCache::getName(Handle handle)
-{
-    if (handle == StringSlicePool::kNullHandle)
-    {
-        return nullptr;
-    }
-
-    Entry& entry = m_entries[int(handle)];
-    if (entry.m_object)
-    {
-        Name* name = dynamicCast<Name>(entry.m_object);
-        if (name)
-        {
-            return name;
-        }
-        StringRepresentation* stringRep = static_cast<StringRepresentation*>(entry.m_object);
-        // Promote it to a name
-        name = m_namePool->getName(String(stringRep));
-        entry.m_object = name;
-        return name;
-    }
-
-    Name* name = m_namePool->getName(String(getStringSlice(handle)));
-    entry.m_object = name;
-    return name;
-}
-
-String StringRepresentationCache::getString(Handle handle)
-{
-    return String(getStringRepresentation(handle));
-}
-
 UnownedStringSlice StringRepresentationCache::getStringSlice(Handle handle) const
 {
     const Entry& entry = m_entries[int(handle)];
@@ -157,44 +118,6 @@ UnownedStringSlice StringRepresentationCache::getStringSlice(Handle handle) cons
     return UnownedStringSlice(start + entry.m_startIndex, int(entry.m_numChars));
 }
 
-StringRepresentation* StringRepresentationCache::getStringRepresentation(Handle handle)
-{
-    if (handle == StringSlicePool::kNullHandle || handle == StringSlicePool::kEmptyHandle)
-    {
-        return nullptr;
-    }
-
-    Entry& entry = m_entries[int(handle)];
-    if (entry.m_object)
-    {
-        Name* name = dynamicCast<Name>(entry.m_object);
-        if (name)
-        {
-            return name->text.getStringRepresentation();
-        }
-        return static_cast<StringRepresentation*>(entry.m_object);
-    }
-
-    const UnownedStringSlice slice = getStringSlice(handle);
-    const UInt size = slice.getLength();
-
-    StringRepresentation* stringRep = StringRepresentation::createWithCapacityAndLength(size, size);
-    memcpy(stringRep->getData(), slice.begin(), size);
-    entry.m_object = stringRep;
-
-    // Keep the StringRepresentation in scope
-    m_scopeManager->add(stringRep);
-    
-    return stringRep;
-}
-
-char* StringRepresentationCache::getCStr(Handle handle)
-{
-    // It turns out StringRepresentation is always 0 terminated, so can just use that
-    StringRepresentation* rep = getStringRepresentation(handle);
-    return rep->getData();
-}
-
 // !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! SerialStringTableUtil !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
 /* static */void SerialStringTableUtil::encodeStringTable(const StringSlicePool& pool, List<char>& stringTable)
diff --git a/source/slang/slang-ir-serialize-types.h b/source/slang/slang-ir-serialize-types.h
index f4340e37e..b6d4572bd 100644
--- a/source/slang/slang-ir-serialize-types.h
+++ b/source/slang/slang-ir-serialize-types.h
@@ -2,7 +2,6 @@
 #ifndef SLANG_IR_SERIALIZE_TYPES_H_INCLUDED
 #define SLANG_IR_SERIALIZE_TYPES_H_INCLUDED
 
-#include "../core/slang-object-scope-manager.h"
 #include "../core/slang-riff.h"
 #include "../core/slang-string-slice-pool.h"
 #include "../core/slang-array-view.h"
@@ -22,6 +21,10 @@ enum class IRSerialCompressionType : uint8_t
 
 class StringRepresentationCache
 {
+    // TODO: The name of this type is no longer accurate to its function.
+    // It doesn't *cache* anything, and instead just provides convenient
+    // access to the contents of a serialized string table.
+
     public:
     typedef StringSlicePool::Handle Handle;
 
@@ -29,29 +32,18 @@ class StringRepresentationCache
     {
         uint32_t m_startIndex;
         uint32_t m_numChars;
-        RefObject* m_object;                ///< Could be nullptr, Name, or StringRepresentation. 
     };
 
-        /// Get as a name
-    Name* getName(Handle handle);
-        /// Get as a string
-    String getString(Handle handle);
-        /// Get as string representation
-    StringRepresentation* getStringRepresentation(Handle handle);
         /// Get as a string slice
     UnownedStringSlice getStringSlice(Handle handle) const;
-        /// Get as a 0 terminated 'c style' string
-    char* getCStr(Handle handle);
 
-        /// Initialize a cache to use a string table, namePool and scopeManager
-    void init(const List<char>* stringTable, NamePool* namePool, ObjectScopeManager* scopeManager);
+        /// Initialize a cache to use a string table
+    void init(const List<char>* stringTable);
 
         /// Ctor
     StringRepresentationCache(); 
     
     protected:
-    ObjectScopeManager* m_scopeManager;
-    NamePool* m_namePool;
     const List<char>* m_stringTable;
     List<Entry> m_entries;
 };
diff --git a/source/slang/slang-ir-serialize.cpp b/source/slang/slang-ir-serialize.cpp
index 4588816f7..369ea37c5 100644
--- a/source/slang/slang-ir-serialize.cpp
+++ b/source/slang/slang-ir-serialize.cpp
@@ -1081,7 +1081,7 @@ static int _calcFixSourceLoc(const IRSerialData::DebugSourceInfo& info, SourceVi
     module->session = session;
 
     // Set up the string rep cache
-    m_stringRepresentationCache.init(&data.m_stringTable, session->getNamePool(), module->getObjectScopeManager());
+    m_stringRepresentationCache.init(&data.m_stringTable);
     
     // Add all the instructions
 
diff --git a/source/slang/slang-ir-serialize.h b/source/slang/slang-ir-serialize.h
index 94c0666bb..cec672b24 100644
--- a/source/slang/slang-ir-serialize.h
+++ b/source/slang/slang-ir-serialize.h
@@ -4,7 +4,6 @@
 
 #include "slang-ir-serialize-types.h"
 
-#include "../core/slang-object-scope-manager.h"
 #include "../core/slang-riff.h"
 
 #include "slang-ir.h"
@@ -132,9 +131,6 @@ struct IRSerialReader
         /// Read a module from serial data
     Result read(const IRSerialData& data, Session* session, SourceManager* sourceManager, RefPtr<IRModule>& moduleOut);
 
-        /// Get the representation cache
-    StringRepresentationCache& getStringRepresentationCache() { return m_stringRepresentationCache; }
-    
     IRSerialReader():
         m_serialData(nullptr),
         m_module(nullptr)
diff --git a/source/slang/slang-ir.h b/source/slang/slang-ir.h
index f3eccad25..a23d6cfa2 100644
--- a/source/slang/slang-ir.h
+++ b/source/slang/slang-ir.h
@@ -12,7 +12,6 @@
 #include "slang-source-loc.h"
 
 #include "../core/slang-memory-arena.h"
-#include "../core/slang-object-scope-manager.h"
 
 #include "slang-type-system-shared.h"
 
@@ -1356,9 +1355,6 @@ struct IRModule : RefObject
 
     IRInstListBase getGlobalInsts() const { return getModuleInst()->getChildren(); }
 
-        /// Get the object scope manager
-    SLANG_FORCE_INLINE ObjectScopeManager* getObjectScopeManager() { return &m_objectScopeManager; }
-
         /// Ctor
     IRModule():
         memoryArena(kMemoryArenaBlockSize)
@@ -1370,10 +1366,6 @@ struct IRModule : RefObject
     // The compilation session in use.
     Session*    session;
     IRModuleInst* moduleInst;
-
-    protected:
-
-    ObjectScopeManager m_objectScopeManager;
 };
 
     /// How much detail to include in dumped IR.