Feature/shared library refactor (#712)

* * Added ISlangSharedLibraryLoader and ISlangSharedLibrary
* Implemented default implementations
* Added slang API function to get/set the ISlangSharedLibraryLoader on the session
* Put function caching onto the Session - so that if the loader is chaged, its easy to reset the shared libraries, and functions

* Run premake.

* Fix problem with setting null, would cause an unnecessary function/shared lib flush.

* * Unload SharedLibrary when DefaultSharedLibrary is deleted.
* Make SharedLibrary handle unload safely if already unloaded.

* Refactor SharedLibrary, such that it becomes a utility class - simplifying it's semantics.

* Simplified ISlangSharedLibrary such that doesn't have unload and isLoaded so easier to implement.
Use updated SharedLibrary impl.

* Disable aarch64 on windows

* Premake windows files without aarch64 build.

* Moved slang-shared-library to core (so can be used in code outside of main slang)
Fixed problem in premake5 where on windows projects were incorrectly constructed

* Allowed RefObject to base class of com types
Added ConfigurableSharedLibraryLoader
Added -dxc-path -fxc-path -glslang-path
Fix problem with dxc-path not honoring it's path when loading dxil

* Added documentation for command line control of dll loading paths.

* Remove some tabbing issues.

* Change name of include guard.

1 files changed, 122 insertions, 0 deletions

diff --git a/source/core/slang-shared-library.h b/source/core/slang-shared-library.h
new file mode 100644
index 000000000..62d15b6b4
--- /dev/null
+++ b/source/core/slang-shared-library.h
@@ -0,0 +1,122 @@
+#ifndef SLANG_SHARED_LIBRARY_H_INCLUDED
+#define SLANG_SHARED_LIBRARY_H_INCLUDED
+
+#include "../../slang.h"
+#include "../../slang-com-helper.h"
+#include "../../slang-com-ptr.h"
+
+#include "../core/platform.h"
+#include "../core/common.h"
+#include "../core/dictionary.h"
+
+namespace Slang
+{
+
+/* NOTE! Do not change this enum without making the appropriate changes to DefaultSharedLibraryLoader::s_libraryNames */
+enum class SharedLibraryType
+{
+    Unknown,            ///< Unknown compiler
+    Dxc,                ///< Dxc compiler
+    Fxc,                ///< Fxc compiler
+    Glslang,            ///< Slang specific glslang compiler
+    Dxil,               ///< Dxil is used with dxc
+    CountOf,
+};
+
+class DefaultSharedLibraryLoader : public ISlangSharedLibraryLoader
+{
+public:
+
+    // ISlangUnknown 
+    // override ref counting, as DefaultSharedLibraryLoader is singleton
+    SLANG_IUNKNOWN_QUERY_INTERFACE 
+    SLANG_NO_THROW uint32_t SLANG_MCALL addRef() SLANG_OVERRIDE { return 1; }
+    SLANG_NO_THROW uint32_t SLANG_MCALL release() SLANG_OVERRIDE { return 1; } 
+
+    // ISlangSharedLibraryLoader
+    virtual SLANG_NO_THROW SlangResult SLANG_MCALL loadSharedLibrary(const char* path, 
+        ISlangSharedLibrary** sharedLibraryOut) SLANG_OVERRIDE;
+
+        /// Get the singleton
+    static DefaultSharedLibraryLoader* getSingleton() { return &s_singleton; }
+
+        /// Get the type from the name
+    static SharedLibraryType getSharedLibraryTypeFromName(const UnownedStringSlice& name);
+
+        /// Get the name from the type, or nullptr if not known
+    static const char* getSharedLibraryNameFromType(SharedLibraryType type) { return s_libraryNames[int(type)]; }
+
+        /// Make a shared library to it's name
+    static const char* s_libraryNames[int(SharedLibraryType::CountOf)];
+
+private:
+        /// Make so not constructible
+    DefaultSharedLibraryLoader() {}
+    virtual ~DefaultSharedLibraryLoader() {}
+
+    ISlangUnknown* getInterface(const Guid& guid);
+
+    static DefaultSharedLibraryLoader s_singleton;
+};
+
+class DefaultSharedLibrary : public ISlangSharedLibrary, public RefObject
+{
+    public:
+    // ISlangUnknown 
+    SLANG_REF_OBJECT_IUNKNOWN_ALL
+
+    // ISlangSharedLibrary
+    virtual SLANG_NO_THROW SlangFuncPtr SLANG_MCALL findFuncByName(char const* name) SLANG_OVERRIDE;
+
+        /// Ctor.
+    DefaultSharedLibrary(const SharedLibrary::Handle sharedLibraryHandle):
+        m_sharedLibraryHandle(sharedLibraryHandle)
+    {
+        SLANG_ASSERT(sharedLibraryHandle);
+    }
+
+        /// Need virtual dtor to keep delete this happy
+    virtual ~DefaultSharedLibrary();
+
+    protected:
+    ISlangUnknown* getInterface(const Guid& guid);
+
+    SharedLibrary::Handle m_sharedLibraryHandle = nullptr;
+};
+
+class ConfigurableSharedLibraryLoader: public ISlangSharedLibraryLoader, public RefObject
+{
+public:
+    typedef Result (*Func)(const char* pathIn, const String& entryString, SharedLibrary::Handle& handleOut);
+
+    // IUnknown
+    SLANG_REF_OBJECT_IUNKNOWN_ALL
+
+    // ISlangSharedLibraryLoader
+    virtual SLANG_NO_THROW SlangResult SLANG_MCALL loadSharedLibrary(const char* path, ISlangSharedLibrary** sharedLibraryOut) SLANG_OVERRIDE;
+
+        /// Function to replace the the path with entryString
+    static Result replace(const char* pathIn, const String& entryString, SharedLibrary::Handle& handleOut);
+        /// Function to change the path using the entryStrinct
+    static Result changePath(const char* pathIn, const String& entryString, SharedLibrary::Handle& handleOut);
+
+    void addEntry(const String& libName, Func func, const String& entryString) { m_entryMap.Add(libName, Entry{ func, entryString} ); }
+    void addEntry(SharedLibraryType libType, Func func, const String& entryString) { m_entryMap.Add(DefaultSharedLibraryLoader::getSharedLibraryNameFromType(libType), Entry { func, entryString} ); }
+
+    virtual ~ConfigurableSharedLibraryLoader() {}
+    protected:
+
+    struct Entry
+    {
+        Func func;
+        String entryString;
+    };
+
+    ISlangUnknown* getInterface(const Guid& guid);
+
+    Dictionary<String, Entry> m_entryMap;
+};
+
+}
+
+#endif // SLANG_SHARED_LIBRARY_H_INCLUDED
\ No newline at end of file