Remove artifact from SourceFile (#2384)

* #include an absolute path didn't work - because paths were taken to always be relative.

* Make DownstreamCompileOptions use POD types.

* CharSliceAllocator -> SliceAllocator
Added SliceConverter
CharSliceCaster -> SliceCaster

* First attempt at zero terminating around blobs.

* Fix clang warning.

* Add SlangTerminatedChars
Make Blob implementations support it.
Make most blobs 'terminated'.

* Fix bug setting up sourceFiles for CommandLineDownstreamCompiler.

* Traffic in TerminatedCharSlice for sourceFiles.
Use ArtifactDesc to generate temporary file names for source.

* Fix typo in testing for shared library/C++.

* Working with source being passed as artifacts to DownstreamCompiler.

* Use artifacts in SourceManager/SourceFile.

* Support infering extension from the original file extension.

* * Infer extension if can't determine from the artifact type
* Split IOSFile/IExtFile representations
* Move responsibility for creating OS file to the handler.

* Disable the check memory path.

* Remove artifact from SourceFile.
Lazily generate SourceFile from artifacts as needed.

* Fix some small bugs.

* Remove maybeAddArtifact.

* Load artifacts if repro capture is enabled.

* Remove adding by string, because doing so means source will be allocated twice or there is a potential race around ref counting to the contained String.

* Add built in source as a blob.

* Fix warning.

* Make StringBlob own the contents if moved.
Fix some compilation issues.

* Share StringBlob uniqueness code.

* Do move unique on Ctor.

* Change MoveUnique to not have any values.

* MoveUnique can more sensibly be a struct.

Co-authored-by: Yong He <yonghe@outlook.com>

13 files changed, 328 insertions, 206 deletions

diff --git a/source/compiler-core/slang-artifact-representation-impl.cpp b/source/compiler-core/slang-artifact-representation-impl.cpp
index 9a5c13311..950ce5d7d 100644
--- a/source/compiler-core/slang-artifact-representation-impl.cpp
+++ b/source/compiler-core/slang-artifact-representation-impl.cpp
@@ -23,7 +23,7 @@ void* ExtFileArtifactRepresentation::getInterface(const Guid& guid)
         guid == IPathArtifactRepresentation::getTypeGuid() ||
         guid == IExtFileArtifactRepresentation::getTypeGuid())
     {
-        return static_cast<IPathArtifactRepresentation*>(this);
+        return static_cast<IExtFileArtifactRepresentation*>(this);
     }
     return nullptr;
 }
diff --git a/source/compiler-core/slang-artifact-representation-impl.h b/source/compiler-core/slang-artifact-representation-impl.h
index da21e30bc..880a90c18 100644
--- a/source/compiler-core/slang-artifact-representation-impl.h
+++ b/source/compiler-core/slang-artifact-representation-impl.h
@@ -108,7 +108,7 @@ protected:
 
 /* This allows wrapping any object to be an artifact representation. 
 
-NOTE! Only allows casting from a single guid. Passing a RefObject across an ABI bounday remains risky!
+NOTE! Only allows casting from a single guid. Passing a RefObject across an ABI boundary remains risky!
 */
 class ObjectArtifactRepresentation : public ComBaseObject, public IArtifactRepresentation
 {
diff --git a/source/compiler-core/slang-include-system.cpp b/source/compiler-core/slang-include-system.cpp
index 9cd193ec6..ebfc8db05 100644
--- a/source/compiler-core/slang-include-system.cpp
+++ b/source/compiler-core/slang-include-system.cpp
@@ -132,8 +132,6 @@ SlangResult IncludeSystem::loadFile(const PathInfo& pathInfo, ComPtr<ISlangBlob>
             sourceFile = m_sourceManager->createSourceFileWithBlob(pathInfo, foundSourceBlob);
             m_sourceManager->addSourceFile(pathInfo.uniqueIdentity, sourceFile);
 
-            sourceFile->maybeAddArtifact(nullptr, m_fileSystemExt);
-
             outBlob = foundSourceBlob;
             return SLANG_OK;
         }
@@ -152,7 +150,6 @@ SlangResult IncludeSystem::loadFile(const PathInfo& pathInfo, ComPtr<ISlangBlob>
             }
 
             sourceFile->setContents(foundSourceBlob);
-            sourceFile->maybeAddArtifact(nullptr, m_fileSystemExt);
 
             outBlob = foundSourceBlob;
             return SLANG_OK;
diff --git a/source/compiler-core/slang-source-loc.cpp b/source/compiler-core/slang-source-loc.cpp
index 6b4c5654d..ac6589e76 100644
--- a/source/compiler-core/slang-source-loc.cpp
+++ b/source/compiler-core/slang-source-loc.cpp
@@ -434,69 +434,6 @@ String SourceFile::calcVerbosePath() const
     return m_pathInfo.foundPath;
 }
 
-void SourceFile::maybeAddArtifact(const ArtifactDesc* inArtifactDesc, ISlangFileSystemExt* ext)
-{
-    if (!m_contentBlob)
-    {
-        return;
-    }
-
-    // If there already is an artifact, we don't need to create one
-    if (m_artifact)
-    {
-        // Check it has a blob and the blob is the same as the content blob
-        SLANG_ASSERT(m_contentBlob == findRepresentation<ISlangBlob>(m_artifact));
-        return;
-    }
-
-    ArtifactDesc artifactDesc;
-
-    if (inArtifactDesc)
-    {
-        artifactDesc = *inArtifactDesc;
-    }
-    else
-    {
-        // Set the default
-        artifactDesc = ArtifactDesc::make(ArtifactKind::Source, ArtifactPayload::Unknown, ArtifactStyle::Unknown);
-
-        // Let's work out from the 
-        // We could try and work it out
-        if (getPathInfo().foundPath.getLength())
-        {
-            // Let's work out what kind of source it is from the this
-            auto desc = ArtifactDescUtil::getDescFromPath(getPathInfo().foundPath.getUnownedSlice());
-
-            // If found something just use that
-            if (desc.kind == ArtifactKind::Source)
-            {
-                artifactDesc = desc;
-            }
-        }
-    }
-
-    // We don't know how the source will be used
-    m_artifact = Artifact::create(artifactDesc);
-
-    // Add the blob as a representation.
-    m_artifact->addRepresentationUnknown(m_contentBlob);
-
-    // If we have the file system, set up the rep to that
-    if (ext)
-    {
-        // Add the representation on the file system
-        auto extRep = new ExtFileArtifactRepresentation(getPathInfo().foundPath.getUnownedSlice(), ext);
-        m_artifact->addRepresentation(extRep);
-    }
-
-    // Get the name 
-    auto name = getPathInfo().getName();
-    if (name.getLength())
-    {
-        m_artifact->setName(name.getBuffer());
-    }
-}
-
 /* !!!!!!!!!!!!!!!!!!!!!!!!! SourceManager !!!!!!!!!!!!!!!!!!!!!!!!!!!! */
 
 void SourceManager::initialize(
diff --git a/source/compiler-core/slang-source-loc.h b/source/compiler-core/slang-source-loc.h
index 29ed9dfbb..66e4c0475 100644
--- a/source/compiler-core/slang-source-loc.h
+++ b/source/compiler-core/slang-source-loc.h
@@ -9,8 +9,6 @@
 #include "../../slang-com-ptr.h"
 #include "../../slang.h"
 
-#include "slang-artifact-representation.h"
-
 namespace Slang {
 
 /** Overview: 
@@ -236,20 +234,11 @@ public:
         /// Get path info
     const PathInfo& getPathInfo() const { return m_pathInfo;  }
 
-        /// Get the (optional) assoicated artifact. Note its desc might be Source/Unknown 
-    IArtifact* getArtifact() const { return m_artifact; }
-        /// Set the artifact
-    void setArtifact(IArtifact* artifact) { m_artifact = artifact; }
-
         /// Set the content as a blob
     void setContents(ISlangBlob* blob);
         /// Set the content as a string
     void setContents(const String& content);
 
-        /// If the desc isn't set, will use Unknown source type
-        /// If artifact isn't defined will try and associate one. 
-    void maybeAddArtifact(const ArtifactDesc* desc, ISlangFileSystemExt* ext);
-
         /// Calculate a display path -> can canonicalize if necessary
     String calcVerbosePath() const;
 
@@ -266,7 +255,6 @@ public:
     SourceManager* m_sourceManager;                             ///< The source manager this belongs to
     PathInfo m_pathInfo;                                        ///< The path The logical file path to report for locations inside this span.
 
-    ComPtr<IArtifact> m_artifact;                               ///< Optional artifact
     ComPtr<ISlangBlob> m_contentBlob;                           ///< A blob that owns the storage for the file contents. If nullptr, there is no contents
     UnownedStringSlice m_content;                               ///< The actual contents of the file.
     size_t m_contentSize;                                       ///< The size of the actual contents
diff --git a/source/core/slang-blob.cpp b/source/core/slang-blob.cpp
index 6cf5214cc..a4acb98cb 100644
--- a/source/core/slang-blob.cpp
+++ b/source/core/slang-blob.cpp
@@ -35,6 +35,25 @@ void* BlobBase::castAs(const SlangUUID& guid)
 
 /* !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! StringBlob !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! */
 
+StringBlob::StringBlob(MoveUnique, String& in)
+{
+    auto rep = in.getStringRepresentation();
+    if (rep && !rep->isUniquelyReferenced())
+    {
+        // Make a new unique copy
+        m_string = in.getUnownedSlice();
+
+        // Move out of in
+        String tmp;
+        tmp.swapWith(in);
+    }
+    else
+    {
+        // Must either not have a rep or be unique
+        m_string.swapWith(in);
+    }
+}
+
 void* StringBlob::castAs(const SlangUUID& guid)
 {
     if (auto intf = getInterface(guid))
@@ -59,6 +78,16 @@ void* StringBlob::getObject(const Guid& guid)
     return nullptr;
 }
 
+/* static */ComPtr<ISlangBlob> StringBlob::moveCreate(String& in)
+{
+    return ComPtr<ISlangBlob>(new StringBlob(MoveUnique{}, in));
+}
+
+/* static */ComPtr<ISlangBlob> StringBlob::moveCreate(String&& in)
+{
+    return ComPtr<ISlangBlob>(new StringBlob(MoveUnique{}, in));
+}
+
 /* !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! RawBlob !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! */
 
 void* RawBlob::castAs(const SlangUUID& guid)
diff --git a/source/core/slang-blob.h b/source/core/slang-blob.h
index 1acf279ef..e528f55a8 100644
--- a/source/core/slang-blob.h
+++ b/source/core/slang-blob.h
@@ -50,17 +50,25 @@ public:
     SLANG_NO_THROW size_t SLANG_MCALL getBufferSize() SLANG_OVERRIDE { return m_string.getLength(); }
 
     static ComPtr<ISlangBlob> create(const String& in) { return ComPtr<ISlangBlob>(new StringBlob(in)); }
-    static ComPtr<ISlangBlob> moveCreate(String& in)
-    {
-        auto blob = new StringBlob;
-        blob->m_string.swapWith(in);
-        return ComPtr<ISlangBlob>(blob);
-    }
+
+        /// Moves from in into the created blob. 
+        /// NOTE! That will only use the representation from in, if it is *unique*
+        /// otherwise it will make a new copy.
+        /// This is so that StringBlob won't hold a reference count via a string held externally.
+        /// In contrast StringBlob::create *may* share the representation.
+    static ComPtr<ISlangBlob> moveCreate(String& in);
+    static ComPtr<ISlangBlob> moveCreate(String&& in);
 
 protected:
+        /// A type that is only used to differentiate a constructor. Can construct with 
+        /// MoveUnique{}
+    struct MoveUnique {};
+
     explicit StringBlob(String const& string)
         : m_string(string)
     {}
+
+    StringBlob(MoveUnique, String& string);
     StringBlob() {}
 
         /// Get the contained string
diff --git a/source/slang/slang-compiler.cpp b/source/slang/slang-compiler.cpp
index ce380681e..06cc9d759 100644
--- a/source/slang/slang-compiler.cpp
+++ b/source/slang/slang-compiler.cpp
@@ -578,6 +578,22 @@ namespace Slang
         }
     }
 
+    SlangResult CodeGenContext::requireTranslationUnitSourceFiles()
+    {
+        if (auto endToEndReq = isPassThroughEnabled())
+        {
+            for (auto entryPointIndex : getEntryPointIndices())
+            {
+                auto translationUnit = getPassThroughTranslationUnit(endToEndReq, entryPointIndex);
+                SLANG_ASSERT(translationUnit);
+                /// Make sure we have the source files
+                SLANG_RETURN_ON_FAIL(translationUnit->requireSourceFiles());
+            }
+        }
+
+        return SLANG_OK;
+    }
+
 #if SLANG_VC
 // TODO(JS): This is a workaround 
 // In debug VS builds there is a warning on line about it being unreachable.
@@ -587,9 +603,11 @@ namespace Slang
 #   pragma warning(disable:4702)
 #endif
     SlangResult CodeGenContext::emitEntryPointsSource(ComPtr<IArtifact>& outArtifact)
-    {
+    {        
         outArtifact.setNull();
 
+        SLANG_RETURN_ON_FAIL(requireTranslationUnitSourceFiles());
+
         auto endToEndReq = isPassThroughEnabled();
         if(endToEndReq)
         {
@@ -597,6 +615,10 @@ namespace Slang
             {
                 auto translationUnit = getPassThroughTranslationUnit(endToEndReq, entryPointIndex);
                 SLANG_ASSERT(translationUnit);
+
+                /// Make sure we have the source files
+                SLANG_RETURN_ON_FAIL(translationUnit->requireSourceFiles());
+
                 // Generate a string that includes the content of
                 // the source file(s), along with a line directive
                 // to ensure that we get reasonable messages
@@ -835,23 +857,7 @@ namespace Slang
         if (compiler->isFileBased())
         {
             // It can only have *one* source file as otherwise we have to combine to make a new source file anyway
-            const auto& sourceFiles = translationUnit->getSourceFiles();
-
-            // The *assumption* here is that if it's file based that assuming it can find the file with the same contents
-            // it can compile directly without having to save off as a file
-            if (sourceFiles.getCount() == 1)
-            {
-                const SourceFile* sourceFile = sourceFiles[0];
-                // We need the path to be found and set
-                // 
-                // NOTE! That the downstream compiler can determine if the path and contents match such that it can be used
-                // without writing file
-                const PathInfo& pathInfo = sourceFile->getPathInfo();
-                if ((pathInfo.type == PathInfo::Type::FoundPath || pathInfo.type == PathInfo::Type::Normal) && pathInfo.foundPath.getLength())
-                {
-                    return false;
-                }
-            }
+            return translationUnit->getSourceArtifacts().getCount() != 1;
         }
         return true;
     }
@@ -1066,12 +1072,10 @@ namespace Slang
             else
             {
                 // Special case if we have a single file, so that we pass the path, and the contents as is.
-                const auto& sourceFiles = translationUnit->getSourceFiles();
-                SLANG_ASSERT(sourceFiles.getCount() == 1);
-
-                SourceFile* sourceFile = sourceFiles[0];
+                const auto& sourceArtifacts = translationUnit->getSourceArtifacts();
+                SLANG_ASSERT(sourceArtifacts.getCount() == 1);
 
-                sourceArtifact = sourceFile->getArtifact();
+                sourceArtifact = sourceArtifacts[0];
                 SLANG_ASSERT(sourceArtifact);
             }
         }
diff --git a/source/slang/slang-compiler.h b/source/slang/slang-compiler.h
index 4c6b0a6b1..8aba89677 100755
--- a/source/slang/slang-compiler.h
+++ b/source/slang/slang-compiler.h
@@ -1381,19 +1381,33 @@ namespace Slang
         // The parent compile request
         FrontEndCompileRequest* compileRequest = nullptr;
 
-        // The language in which the source file(s)
-        // are assumed to be written
+            // The language in which the source file(s)
+            // are assumed to be written
         SourceLanguage sourceLanguage = SourceLanguage::Unknown;
 
-        // The source file(s) that will be compiled to form this translation unit
-        //
-        // Usually, for HLSL or GLSL there will be only one file.
-        List<SourceFile*> m_sourceFiles;
+            /// Makes any source artifact available as a SourceFile.
+            /// If successful any of the source artifacts will be represented by the same index 
+            /// of sourceArtifacts
+        SlangResult requireSourceFiles();
+
+            /// Get the source files. 
+            /// Since lazily evaluated requires calling requireSourceFiles to know it's in sync
+            /// with sourceArtifacts.
+        List<SourceFile*> const& getSourceFiles();
+        
+            /// Get the source artifacts associated 
+        const List<ComPtr<IArtifact>>& getSourceArtifacts() const { return m_sourceArtifacts; }
+
+            /// Clear all of the source
+        void clearSource() { m_sourceArtifacts.clear(); m_sourceFiles.clear(); }
+
+            /// Add a source artifact
+        void addSourceArtifact(IArtifact* sourceArtifact);
 
-        List<SourceFile*> const& getSourceFiles() { return m_sourceFiles; }
-        void addSourceFile(SourceFile* sourceFile);
+            /// Add both the artifact and the sourceFile. 
+        void addSource(IArtifact* sourceArtifact, SourceFile* sourceFile);
 
-        // The entry points associated with this translation unit
+            // The entry points associated with this translation unit
         List<RefPtr<EntryPoint>> const& getEntryPoints() { return module->getEntryPoints(); }
 
         void _addEntryPoint(EntryPoint* entryPoint) { module->_addEntryPoint(entryPoint); }
@@ -1414,6 +1428,17 @@ namespace Slang
         Session* getSession();
         NamePool* getNamePool();
         SourceManager* getSourceManager();
+
+    protected:
+        void _addSourceFile(SourceFile* sourceFile);
+
+        List<ComPtr<IArtifact>> m_sourceArtifacts;
+        // The source file(s) that will be compiled to form this translation unit
+        //
+        // Usually, for HLSL or GLSL there will be only one file.
+        // NOTE! This member is generated lazily from m_sourceArtifacts
+        // it is *necessary* to call requireSourceFiles to ensure it's in sync.
+        List<SourceFile*> m_sourceFiles;
     };
 
     enum class FloatingPointMode : SlangFloatingPointModeIntegral
@@ -2007,20 +2032,15 @@ namespace Slang
 
         int addTranslationUnit(TranslationUnitRequest* translationUnit);
 
-        void addTranslationUnitSourceFile(
+        void addTranslationUnitSourceArtifact(
             int             translationUnitIndex,
-            SourceFile*     sourceFile);
+            IArtifact*      sourceArtifact);
 
         void addTranslationUnitSourceBlob(
             int             translationUnitIndex,
             String const&   path,
             ISlangBlob*     sourceBlob);
 
-        void addTranslationUnitSourceString(
-            int             translationUnitIndex,
-            String const&   path,
-            String const&   source);
-
         void addTranslationUnitSourceFile(
             int             translationUnitIndex,
             String const&   path);
@@ -2386,6 +2406,8 @@ namespace Slang
 
         bool isSpecializationDisabled();
 
+        SlangResult requireTranslationUnitSourceFiles();
+
         //
 
         SlangResult emitEntryPoints(ComPtr<IArtifact>& outArtifact);
@@ -2890,7 +2912,7 @@ namespace Slang
         void addBuiltinSource(
             Scope*                  scope,
             String const&           path,
-            String const&           source);
+            ISlangBlob*             sourceBlob);
         ~Session();
 
         void addDownstreamCompileTime(double time) { m_downstreamCompileTime += time; }
diff --git a/source/slang/slang-preprocessor.cpp b/source/slang/slang-preprocessor.cpp
index 739860915..fca8f5029 100644
--- a/source/slang/slang-preprocessor.cpp
+++ b/source/slang/slang-preprocessor.cpp
@@ -3057,9 +3057,6 @@ static void HandleIncludeDirective(PreprocessorDirectiveContext* context)
 
         sourceFile = sourceManager->createSourceFileWithBlob(filePathInfo, foundSourceBlob);
 
-        auto fileSystemExt = context->m_preprocessor->fileSystem;
-        sourceFile->maybeAddArtifact(nullptr, fileSystemExt);
-
         sourceManager->addSourceFile(filePathInfo.uniqueIdentity, sourceFile);
     }
 
diff --git a/source/slang/slang-reflection-api.cpp b/source/slang/slang-reflection-api.cpp
index ae43f9113..eb2b9aff9 100644
--- a/source/slang/slang-reflection-api.cpp
+++ b/source/slang/slang-reflection-api.cpp
@@ -1245,7 +1245,7 @@ namespace Slang
             auto access = resourceType->getAccess();
             auto mutableFlag = access != SLANG_RESOURCE_ACCESS_READ ? SLANG_BINDING_TYPE_MUTABLE_FLAG : 0;
 
-            switch( shape )
+            switch(SlangResourceShape(shape ))
             {
             default:
                 return SlangBindingType(SLANG_BINDING_TYPE_TEXTURE | mutableFlag);
diff --git a/source/slang/slang-repro.cpp b/source/slang/slang-repro.cpp
index aa4dc92fc..1597366d6 100644
--- a/source/slang/slang-repro.cpp
+++ b/source/slang/slang-repro.cpp
@@ -10,6 +10,9 @@
 
 #include "slang-options.h"
 
+#include "../compiler-core/slang-artifact-util.h"
+#include "../compiler-core/slang-artifact-desc-util.h"
+
 #include "../compiler-core/slang-source-loc.h"
 
 namespace Slang {
@@ -996,15 +999,25 @@ struct LoadContext
             dstTranslationUnit->moduleName = moduleName;
 
             const auto& srcSourceFiles = srcTranslationUnit.sourceFiles;
-            auto& dstSourceFiles = dstTranslationUnit->m_sourceFiles;
 
-            dstSourceFiles.clear();
+            dstTranslationUnit->clearSource();
+
+            const auto sourceDesc = ArtifactDescUtil::makeDescForSourceLanguage(asExternal(dstTranslationUnit->sourceLanguage));
 
             for (Index j = 0; j < srcSourceFiles.getCount(); ++j)
             {
+                // Create the source file
                 SourceFile* sourceFile = context.getSourceFile(base.asRaw(base.asRaw(srcSourceFiles[i])));
+
+                // Create the artifact
+                auto sourceArtifact = ArtifactUtil::createArtifact(sourceDesc, sourceFile->getPathInfo().getName().getBuffer());
+                if (sourceFile->getContentBlob())
+                {
+                    sourceArtifact->addRepresentationUnknown(sourceFile->getContentBlob());
+                }
+
                 // Add to translation unit
-                dstTranslationUnit->addSourceFile(sourceFile);
+                dstTranslationUnit->addSource(sourceArtifact, sourceFile);
             }
         }
     }
diff --git a/source/slang/slang.cpp b/source/slang/slang.cpp
index a7a4fc8dc..18b9b3c99 100644
--- a/source/slang/slang.cpp
+++ b/source/slang/slang.cpp
@@ -249,13 +249,15 @@ void Session::_initCodeGenTransitionMap()
 
 void Session::addBuiltins(
     char const*     sourcePath,
-    char const*     sourceString)
+    char const*     source)
 {
+    auto sourceBlob = StringBlob::moveCreate(String(source));
+
     // TODO(tfoley): Add ability to directly new builtins to the appropriate scope
     addBuiltinSource(
         coreLanguageScope,
         sourcePath,
-        sourceString);
+        sourceBlob);
 }
 
 void Session::setSharedLibraryLoader(ISlangSharedLibraryLoader* loader)
@@ -295,9 +297,9 @@ SlangResult Session::compileStdLib(slang::CompileStdLibFlags compileFlags)
     }
 
     // TODO(JS): Could make this return a SlangResult as opposed to exception
-    addBuiltinSource(coreLanguageScope, "core", getCoreLibraryCode());
-    addBuiltinSource(hlslLanguageScope, "hlsl", getHLSLLibraryCode());
-    addBuiltinSource(autodiffLanguageScope, "diff", getAutodiffLibraryCode());
+    addBuiltinSource(coreLanguageScope, "core", StringBlob::moveCreate(getCoreLibraryCode()));
+    addBuiltinSource(hlslLanguageScope, "hlsl", StringBlob::moveCreate(getHLSLLibraryCode()));
+    addBuiltinSource(autodiffLanguageScope, "diff", StringBlob::moveCreate(getAutodiffLibraryCode()));
 
     if (compileFlags & slang::CompileStdLibFlag::WriteDocumentation)
     {
@@ -1489,7 +1491,120 @@ SourceManager* TranslationUnitRequest::getSourceManager()
     return compileRequest->getSourceManager();
 }
 
-void TranslationUnitRequest::addSourceFile(SourceFile* sourceFile)
+void TranslationUnitRequest::addSourceArtifact(IArtifact* sourceArtifact)
+{
+    SLANG_ASSERT(sourceArtifact);
+    m_sourceArtifacts.add(ComPtr<IArtifact>(sourceArtifact));
+}
+
+
+void TranslationUnitRequest::addSource(IArtifact* sourceArtifact, SourceFile* sourceFile)
+{
+    SLANG_ASSERT(sourceArtifact && sourceFile);
+    // Must be in sync!
+    SLANG_ASSERT(m_sourceFiles.getCount() == m_sourceArtifacts.getCount());
+
+    addSourceArtifact(sourceArtifact);
+    _addSourceFile(sourceFile);
+}
+
+SlangResult TranslationUnitRequest::requireSourceFiles()
+{
+    SLANG_ASSERT(m_sourceFiles.getCount() <= m_sourceArtifacts.getCount());
+
+    if (m_sourceFiles.getCount() == m_sourceArtifacts.getCount())
+    {
+        return SLANG_OK;
+    }
+
+    auto sink = compileRequest->getSink();
+    SourceManager* sourceManager = compileRequest->getSourceManager();
+
+    // Get he linkage file system
+    //ISlangFileSystemExt* linkageFileSystem = compileRequest->getLinkage()->getFileSystemExt();
+
+    for (Index i = m_sourceFiles.getCount(); i < m_sourceArtifacts.getCount(); ++i)
+    {
+        IArtifact* artifact = m_sourceArtifacts[i];
+
+        PathInfo pathInfo = PathInfo::makeUnknown();
+        
+        if (auto extRep = findRepresentation<IExtFileArtifactRepresentation>(artifact))
+        {
+            auto extFileSystem = extRep->getFileSystem();
+
+            // TODO(JS): 
+            // Ideally we'd confirm that the file system was the same, such we could know that the unique 
+            // identity is appropriate for the current file system.
+            //
+            // We just assume compatibility for the moment, because repro will be a different file system
+            // but we need to use the unique identity that is there.
+      
+            //if (extFileSystem == linkageFileSystem)
+            {
+                // Get the unique identity
+                ComPtr<ISlangBlob> uniqueIdentityBlob;
+                if (SLANG_SUCCEEDED(extFileSystem->getFileUniqueIdentity(extRep->getPath(), uniqueIdentityBlob.writeRef())) && uniqueIdentityBlob)
+                {
+                    auto uniqueIdentity = StringUtil::getString(uniqueIdentityBlob);
+
+                    // See if this an already loaded source file
+                    if (auto sourceFile = sourceManager->findSourceFileRecursively(uniqueIdentity))
+                    {
+                        // If the source file has a blob, and the artifact doesn't copy over that representation
+                        if (sourceFile->getContentBlob() && findRepresentation<ISlangBlob>(artifact) == nullptr)
+                        {
+                            artifact->addRepresentationUnknown(sourceFile->getContentBlob());
+                        }
+
+                        _addSourceFile(sourceFile);
+                        continue;
+                    }
+
+                    pathInfo = PathInfo::makeNormal(extRep->getPath(), uniqueIdentity);
+                }
+                else
+                {
+                    pathInfo = PathInfo::makePath(extRep->getPath());
+                }
+            }
+        }
+
+        if (pathInfo.type == PathInfo::Type::Unknown)
+        {
+            const auto path = ArtifactUtil::findPath(artifact);
+
+            // If has a path representation we'll make it a FoundPath
+            if (findRepresentation<IPathArtifactRepresentation>(artifact))
+            {
+                pathInfo = PathInfo::makePath(path);
+            }
+            else
+            {
+                // Otherwise we'll assume it's created from a 'String' even if that's not quite the case
+                pathInfo = PathInfo::makeFromString(path);
+            }
+        }
+
+        ComPtr<ISlangBlob> blob;
+        const SlangResult blobRes = artifact->loadBlob(ArtifactKeep::Yes, blob.writeRef());
+        if (SLANG_FAILED(blobRes))
+        {
+            // Report couldn't load
+            sink->diagnose(SourceLoc(),
+                Diagnostics::cannotOpenFile,
+                pathInfo.getName());
+            return blobRes;
+        }
+        
+        auto sourceFile = sourceManager->createSourceFileWithBlob(pathInfo, blob);
+        _addSourceFile(sourceFile);
+    }
+
+    return SLANG_OK;
+}
+
+void TranslationUnitRequest::_addSourceFile(SourceFile* sourceFile)
 {
     m_sourceFiles.add(sourceFile);
 
@@ -1505,6 +1620,12 @@ void TranslationUnitRequest::addSourceFile(SourceFile* sourceFile)
     }
 }
 
+List<SourceFile*> const& TranslationUnitRequest::getSourceFiles() 
+{ 
+    SLANG_ASSERT(m_sourceArtifacts.getCount() == m_sourceFiles.getCount());
+    return m_sourceFiles; 
+}
+
 EndToEndCompileRequest::~EndToEndCompileRequest()
 {
     // Flush any writers associated with the request
@@ -2246,8 +2367,11 @@ SlangResult FrontEndCompileRequest::executeActionsInner()
     // We currently allow GlSL files on the command line so that we can
     // drive our "pass-through" mode, but we really want to issue an error
     // message if the user is seriously asking us to compile them.
-    for (auto& translationUnit : translationUnits)
+    for (TranslationUnitRequest* translationUnit : translationUnits)
     {
+        // Make sure SourceFile representation is available for all translationUnits
+        SLANG_RETURN_ON_FAIL(translationUnit->requireSourceFiles());
+
         switch(translationUnit->sourceLanguage)
         {
         default:
@@ -2261,9 +2385,9 @@ SlangResult FrontEndCompileRequest::executeActionsInner()
 
 
     // Parse everything from the input files requested
-    for (auto& translationUnit : translationUnits)
+    for (TranslationUnitRequest* translationUnit : translationUnits)
     {
-        parseTranslationUnit(translationUnit.Ptr());
+        parseTranslationUnit(translationUnit);
     }
 
     if (outputPreprocessor)
@@ -2559,47 +2683,14 @@ int FrontEndCompileRequest::addTranslationUnit(TranslationUnitRequest* translati
     return (int) result;
 }
 
-
-void FrontEndCompileRequest::addTranslationUnitSourceFile(
+void FrontEndCompileRequest::addTranslationUnitSourceArtifact(
     int             translationUnitIndex,
-    SourceFile*     sourceFile)
+    IArtifact*      sourceArtifact)
 {
     auto translationUnit = translationUnits[translationUnitIndex];
     
-    // TODO(JS): 
-    // The larger problem here is that a file on a file system *could* be interpretted in different ways.
-    // When the user supplies the source as a string, we use the source type specified for the translation unit.
-    // 
-    // If it's on the file system it could be (say) compiled as HLSL or some other way. A *downstream* compiler
-    // that used the file system may care.  
-    //
-    // We will assume here, that if it's loaded from the file system, it's path extension defines how it should be interpretted
-    // If that wasn't the case we'd have to either *copy*, or do some command line fiddling to tell it for the downstream compiler
-    // what the file is. 
-
-    const auto& pathInfo = sourceFile->getPathInfo();
-    const auto pathType = pathInfo.type;
-
-    switch (pathType)
-    {
-        case PathInfo::Type::FromString:
-        {
-            // Set the artifact type from the the source language type
-            auto sourceDesc = ArtifactDescUtil::makeDescForSourceLanguage(asExternal(translationUnit->sourceLanguage));
-            sourceFile->maybeAddArtifact(&sourceDesc, nullptr);
-            break;
-        }
-        case PathInfo::Type::FoundPath:
-        case PathInfo::Type::Normal:
-        {
-            // We'll *not* use the source for the artifact type. Doing so will lead to the type being determined via extension
-            sourceFile->maybeAddArtifact(nullptr, getLinkage()->getFileSystemExt());
-            break;
-        }
-    }
-
     // Add the source file
-    translationUnit->addSourceFile(sourceFile);
+    translationUnit->addSourceArtifact(sourceArtifact);
 }
 
 void FrontEndCompileRequest::addTranslationUnitSourceBlob(
@@ -2607,21 +2698,13 @@ void FrontEndCompileRequest::addTranslationUnitSourceBlob(
     String const&   path,
     ISlangBlob*     sourceBlob)
 {
-    // The path specified may or may not be a file path - mark as being constructed 'FromString'.
-    SourceFile* sourceFile = getSourceManager()->createSourceFileWithBlob(PathInfo::makeFromString(path), sourceBlob);
-    
-    addTranslationUnitSourceFile(translationUnitIndex, sourceFile);
-}
+    auto translationUnit = translationUnits[translationUnitIndex];
+    auto sourceDesc = ArtifactDescUtil::makeDescForSourceLanguage(asExternal(translationUnit->sourceLanguage));
 
-void FrontEndCompileRequest::addTranslationUnitSourceString(
-    int             translationUnitIndex,
-    String const&   path,
-    String const&   source)
-{
-    // The path specified may or may not be a file path - mark as being constructed 'FromString'.
-    SourceFile* sourceFile = getSourceManager()->createSourceFileWithString(PathInfo::makeFromString(path), source);
+    auto artifact = ArtifactUtil::createArtifact(sourceDesc, path.getBuffer());
+    artifact->addRepresentationUnknown(sourceBlob);
 
-    addTranslationUnitSourceFile(translationUnitIndex, sourceFile);
+    translationUnit->addSourceArtifact(artifact);
 }
 
 void FrontEndCompileRequest::addTranslationUnitSourceFile(
@@ -2636,11 +2719,35 @@ void FrontEndCompileRequest::addTranslationUnitSourceFile(
     // paths were not taken into account by this function.
     //
 
-    PathInfo pathInfo;
+    auto fileSystemExt = getLinkage()->getFileSystemExt();
+    auto translationUnit = getTranslationUnit(translationUnitIndex);
+
+    auto sourceDesc = ArtifactDescUtil::makeDescForSourceLanguage(asExternal(translationUnit->sourceLanguage));
+
+    auto sourceArtifact = ArtifactUtil::createArtifact(sourceDesc);
 
-    ComPtr<ISlangBlob> sourceBlob;
-    SlangResult result = loadFile(path, pathInfo, sourceBlob.writeRef());
-    if(SLANG_FAILED(result))
+    auto extRep = new ExtFileArtifactRepresentation(path.getUnownedSlice(), fileSystemExt);
+    sourceArtifact->addRepresentation(extRep);
+
+    SlangResult existsRes = SLANG_OK;
+
+    // If we require caching, we demand it's loaded here.
+    // 
+    // In practice this probably means repro capture is enabled. So we want to 
+    // load the blob such that it's in the cache, even if it doesn't actually 
+    // have to be loaded for the compilation.
+    if (getLinkage()->m_requireCacheFileSystem)
+    {
+        ComPtr<ISlangBlob> blob;
+        // If we can load the blob, then it exists
+        existsRes = sourceArtifact->loadBlob(ArtifactKeep::Yes, blob.writeRef());
+    }
+    else
+    {
+        existsRes = sourceArtifact->exists() ? SLANG_OK : SLANG_E_NOT_FOUND;
+    }
+
+    if (SLANG_FAILED(existsRes))
     {
         // Emit a diagnostic!
         getSink()->diagnose(
@@ -2650,10 +2757,7 @@ void FrontEndCompileRequest::addTranslationUnitSourceFile(
         return;
     }
 
-    // Was loaded from the specified path
-    SourceFile* sourceFile = getSourceManager()->createSourceFileWithBlob(pathInfo, sourceBlob);
-
-    addTranslationUnitSourceFile(translationUnitIndex, sourceFile);
+    translationUnit->addSourceArtifact(sourceArtifact);
 }
 
 int FrontEndCompileRequest::addEntryPoint(
@@ -2808,10 +2912,29 @@ RefPtr<Module> Linkage::loadModule(
         name,
         srcLoc);
 
+    // Create an artifact for the source
+    auto sourceArtifact = ArtifactUtil::createArtifact(ArtifactDesc::make(ArtifactKind::Source, ArtifactPayload::Slang, ArtifactStyle::Unknown));
+
     // Create with the 'friendly' name
-    SourceFile* sourceFile = getSourceManager()->createSourceFileWithBlob(filePathInfo, sourceBlob);
-    
-    translationUnit->addSourceFile(sourceFile);
+    if (filePathInfo.type == PathInfo::Type::Normal ||
+        filePathInfo.type == PathInfo::Type::FoundPath)
+    {
+        // We create that it was loaded from the file system
+        sourceArtifact->addRepresentation(new ExtFileArtifactRepresentation(filePathInfo.foundPath.getUnownedSlice(), getFileSystemExt()));
+    }
+    else
+    {
+        // Else we say we don't know and just add the blob
+        sourceArtifact->addRepresentationUnknown(sourceBlob);
+    }
+
+    translationUnit->addSourceArtifact(sourceArtifact);
+
+    if (SLANG_FAILED(translationUnit->requireSourceFiles()))
+    {
+        // Some problem accessing source files
+        return nullptr;
+    }
 
     int errorCountBefore = sink->getErrorCount();
     frontEndReq->parseTranslationUnit(translationUnit);
@@ -4234,7 +4357,7 @@ RefPtr<Module> findOrImportModule(
 void Session::addBuiltinSource(
     Scope*                  scope,
     String const&           path,
-    String const&           source)
+    ISlangBlob*             sourceBlob)
 {
     SourceManager* sourceManager = getBuiltinSourceManager();
 
@@ -4254,10 +4377,10 @@ void Session::addBuiltinSource(
     Name* moduleName = getNamePool()->getName(path);
     auto translationUnitIndex = compileRequest->addTranslationUnit(SourceLanguage::Slang, moduleName);
 
-    compileRequest->addTranslationUnitSourceString(
+    compileRequest->addTranslationUnitSourceBlob(
         translationUnitIndex,
         path,
-        source);
+        sourceBlob);
 
     SlangResult res = compileRequest->executeActionsInner();
     if (SLANG_FAILED(res))
@@ -4637,7 +4760,11 @@ void EndToEndCompileRequest::addTranslationUnitSourceStringSpan(int translationU
 
     if (!path) path = "";
 
-    frontEndReq->addTranslationUnitSourceString(translationUnitIndex, path, UnownedStringSlice(sourceBegin, sourceEnd));
+    const auto slice = UnownedStringSlice(sourceBegin, sourceEnd);
+
+    auto blob = RawBlob::create(slice.begin(), slice.getLength());
+
+    frontEndReq->addTranslationUnitSourceBlob(translationUnitIndex, path, blob);
 }
 
 void EndToEndCompileRequest::addTranslationUnitSourceBlob(int translationUnitIndex, char const* path, ISlangBlob* sourceBlob)